Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

A practical technique for determining the length of a silicon nanowire (SiNW) array is reported by the analysis of reflected images from a smartphone camera. The SiNW array was prepared by electroless chemical etching and its length controlled by the etching time of a Si wafer. The average lengths for the SiNW array were characterized by scanning electron microscopy. The relationship between the reflection spectrum and the length of the SiNW array was investigated. The ratio of percent reflectance from 900 to 550 nm exponentially increased from 1.8 +/- 0.1 to 22.2 +/- 1.3 when the average length increased from 184 +/- 12 to 1237 +/- 23 nm. Optical sensing for characterization of the length of SiNW was further developed into a simple and practical technique using a smartphone camera as a detector. A 3D printed tool was assembled to the smartphone to control the light path and the reflected image of the SiNW array was acquired. The reflected intensity ratio obtained from the reflected images with long pass to short pass filters increased analogously to the spectroscopic results. This optical-sensing-based smartphone showed simple and rapid detection for determining the lengths of a SiNW array and a SiNW array coated with a polymer film. This platform is compact and capable of on-site detecting and is promising for the characterization of reflective materials.

DOI： 10.1080/10739149.2021.1887889

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society for Analytical Chemistry  

DOI： 10.2116/analsci.20r005

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Publishing type：Research paper (scientific journal)   Publisher：Institute of Electronics, Information and Communications Engineers (IEICE)  

DOI： 10.1587/transele.2020oms0008

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Three different silver nanoprisms (AgNPrs) were combined and used as light-trapping materials in organic solar cells (OSCs). These mixed AgNPrs (M-AgNPrs) increased the photocarrier generation in the OSCs due to the broadband absorption, which was attributed to mutual multiple plasmonic excitations covering the entire visible light region. The M-AgNPrs were incorporated into a poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) hole-transport layer in the OSCs. The UV–vis spectra, atomic force microscope images and current density versus voltage curves of the fabricated devices were recorded at different loading concentrations of the M-AgNPrs. Finite-difference time-domain simulation, impedance spectroscopy, and measurement of incident photon-to-current efficiency of the devices confirmed the effect of the multiple plasmonic excitations. The results suggest that, in an optimum condition, the efficiency of the OSCs loaded with M-AgNPrs was 7.9% higher than the reference OSC.

DOI： 10.1016/j.jsamd.2021.02.007

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Royal Society  

We studied the effect of gold quantum dots (AuQDs)/grating-coupled surface plasmon resonance (GC-SPR) in inverted organic solar cells (OSCs). AuQDs are located within a GC-SPR evanescent field in inverted OSCs, indicating an interaction between GC-SPR and AuQDs' quantum effects, subsequently giving rise to improvement in the performance of inverted OSCs. The fabricated solar cell device comprises an ITO/TiO ₂ /P3HT : PCBM/PEDOT : PSS : AuQD/silver grating structure. The AuQDs were loaded into a hole transport layer (PEDOT : PSS) of the inverted OSCs to increase absorption in the near-ultraviolet (UV) light region and to emit visible light into the neighbouring photoactive layer, thereby achieving light-harvesting improvement of the device. The grating structures were fabricated on P3HT:PCBM layers using a nanoimprinting technique to induce GC-SPR within the inverted OSCs. The AuQDs incorporated within the strongly enhanced GC-SPR evanescent electric field on metallic nanostructures in the inverted OSCs improved the short-circuit current and the efficiency of photovoltaic devices. In comparison with the reference OSC and OSCs with only green AuQDs or only metallic grating, the developed device indicates enhancement of up to 16% power conversion efficiency. This indicates that our light management approach allows for greater light utilization of the OSCs because of the synergistic effect of G-AuQDs and GC-SPR.

DOI： 10.1098/rsos.210022

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Other Link： https://royalsocietypublishing.org/doi/full-xml/10.1098/rsos.210022

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

In this work, we investigate surface plasmon field-enhanced fluorescence (SPF) emission from gold quantum dots (AuQDs) on a polyelectrolyte multilayer ultrathin film deposited onto an Al thin film. Polyelectrolyte layers of poly(diallyl dimethyl ammonium chloride) (PDADMAC) and poly(sodium 4-styrenesulfonate) (PSS) are deposited onto the Al surface using a layer-by-layer (LbL) adsorption technique. AuQDs are subsequently deposited onto the PDADMAC/PSS ultrathin films to study their fluorescence enhancement/quenching phenomenon, as monitored by SPF spectroscopy. The distance between the AuQDs and the Al thin film is controlled by the number of deposited PDADMAC/PSS LbL films. With increasing number of the PDADMAC/PSS bilayers, the fluorescence intensity of the AuQDs increases until the optimum distance between the AuQDs and Al layers is achieved. Moreover, silver nanoprisms (AgNPrs) are coated onto the AuQDs for H2O2 sensing. When the AgNPrs are present, a decrease in the fluorescence intensity of the AuQDs due to energy transfer from the AuQDs to the AgNPrs is observed. Recovery of the fluorescence intensity of the AuQDs is observed upon injection of a H2O2 solution, where the recovery of the intensity is proportional to the H2O2 concentration in the range from 1 pM to 100 nM and results from the oxidation reaction or etching of the AgNPrs. The fluorescence recovery is attributed to weakening of the quenching effect by a reduction in concentration of the AgNPrs. The proposed system exhibits strong potential for the development of H2O2 sensors.

DOI： 10.1007/s11468-021-01388-8

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Other Link： https://link.springer.com/article/10.1007/s11468-021-01388-8/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER  

The method for fabricating a grating prism surface plasmon resonance (SPR) sensor chip was developed. The grating prism was 3D-printed by a stereolithography 3D printer and subsequently created a grating pattern by soft lithography. A gold film was thermally evaporated on the grating prism. Moreover, a liquid cell was 3D-printed and assembled into a gold-coated grating prism. To make the sensor chip compact and practical, a compatible prism holder was 3D-printed by a fused deposition model 3D printer. The SPR sensor chip was mounted on the rotation stage and the SPR spectrum was recorded by spectrometer. The SPR excitation of the sensor chip can be extended to the near-infrared region by creating a grating pattern on the prism surface. A gold-coated grating prism exhibited dual modes of SPR excitations, namely, prism-coupling SPR (PC-SPR) and grating-coupling SPR (GC-SPR). The dual-mode SPR excitation was observed at the incident angles of 45 degrees-80 degrees. When the incident angle increased, the SPR excitation of the PC-SPR mode exhibited a blue shift in the wavelength region of 480-690 nm, whereas the GC-SPR mode exhibited a red shift in the wavelength region of 670-770 nm. The surface plasmon (SP) dispersion obtained from the dual-mode SPR configuration confirmed observable PC-SPR (which corresponded to + SP0 of the gold-resin interface) and GC-SPR (which corresponded to -SP+1 of the gold-air interface), which could be excited from the developed substrate. The refractive index sensitivities of the PCSPR and GC-SPR modes were 2924.4 and 414.9 nm RIU-1, respectively. The SPR excitations of the sensor chip exhibited a simultaneous shift when the local refractive index of the materials adjacent to the gold-coated grating prism surface was changed, especially the material that had overlapping light absorption at the SPR excitation wavelength. Using this fabrication process, the prism is designed and then printed; moreover, the grating pattern on the prism surface can be employed to tune the SPR excitation wavelength of the sensor chip for the versatility and broad perspective of the optical sensing-based SPR. (C) 2020 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.aca.2020.12.027

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

Several scientific works have reported the use of colloidal gold nanoparticle (AuNP) solutions as a colorimetric probe for creatinine detection. Nonetheless, urinary protein is one of the primary chemical components that can interfere with creatinine detection. In this work, we developed a colorimetric probe using AuNP colloidal solution to detect creatinine in the urine of proteinuria patients. A microchamber array was prepared to minimize the sample volume and was used to simultaneously perform spectral recording and image acquisition of several samples. The analyzed volume for each sample was 15 mu L. A camera coupled with liquid crystal tunable filters was used to record hyperspectral images, and the signals were then converted to localized surface plasmon resonance (LSPR) spectra. Color changes in the AuNP colloidal solution in the presence of varying concentrations of creatinine and human serum albumin (HSA) indicated different features and could be detected by a hyperspectral imaging technique. The relevant concentration ranges of creatinine and HSA were 5 - 200 and 50 - 250 mg dL(-1), respectively. Furthermore, a smartphone camera was adopted to record a color mapping image of the AuNP colloidal solution in the presence of creatinine and HSA at these concentration ranges. Contour plots of red and blue chromaticity levels from color mappings were produced, and 2D fitting equations obtained from these contour plots were adopted to determine the creatinine concentration in the urine of proteinuria patients. This practical technique can be used for screening and can be further developed as a household biosensing device for urinalysis.

DOI： 10.2116/analsci.20P235

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

A novel optical waveguide sensor utilizing surface plasmon resonance (SPR) that enables the measurement of optical absorption and the thickness of a thin film was proposed. A BK-7 glass slide was used as a waveguide core, and an Ag/Au film of 5 mm width and transparent polymethyl methacrylate-co-methacrylic acid (PMMA-co-PMAA) were consecutively deposited to develop the sensor. The PMMA-co-PMAA film was used to control the SPR wavelength. This sensor allows us to measure the optical absorption and thickness of the deposited film using the evanescent wave from the waveguide and the SPR phenomena, respectively. In order to demonstrate this, a layer-by-layer deposit of a film of water-soluble phthalocyanine dye (Alcian blue, pyridine variant, AB) and polystyrenesulfonate was observed. Additionally, adsorptions from a mixed solution of AB and polydiallyldimethylammonium chloride were observed.

DOI： 10.35848/1347-4065/abbfe6

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Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/abbfe6/pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

In this study, we demonstrate the fabrication of hybrid plasmonic solar cells using gold nanoparticles (AuNPs). Two types of AuNPs, gold nanospheres (AuNSs) and gold nanorods (AuNRs), were incorporated in a hole transport layer (HTL) (PEDOT:PSS) on a metallic grating electrode. The organic solar cells (OSCs) structure comprised an indium-tin-oxide (ITO)-coated glass substrate/PEDOT:PSS:AuNSs:AuNRs/P3HT:PCBM/Al grating electrode. Adding AuNPs induced localized surface plasmon resonance (LSPR), while grating structured Al at the interface with a photoactive layer excited the propagating surface plasmons. Compared with a flat reference device, the proposed OSCs exhibited improved photovoltaic properties by increasing both the short-circuit current density (JSC) and the power conversion efficiency (PCE) with large enhancements of 16.23% and 14.06%, respectively. The efficiency improvement was attributed to increased broadband absorption and improved electrical properties inside the thin-film devices.

DOI： 10.1080/15421406.2020.1741822

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

<p>The performance of organic solar cells was improved by the effect of a synergistic gold quantum dot/plasmonic grating system.</p>

DOI： 10.1039/d0na00169d

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Surface plasmon resonance (SPR) technique is a great tool to investigate the binding of analyte to functionalized surfaces and the immobilization of biomolecules. Creatinine is one of the biomarkers for monitoring renal functions and making a diagnosis of kidney disease. Elevated creatinine levels in the human body signifies impaired kidney disease. In this work, we developed a new strategy for creatinine detection using starch stabilized silver nanoparticles (starch-AgNPs) on poly(pyrrole) (PPy) thin film using the SPR technique. The assay exhibited the obvious change from yellow to orange color of AgNPs solution in the presence of creatinine, showing good sensitivity due to the localized plasmon effect of AgNPs. Based on this effect, the change of SPR reflectivity in the Kretschmann configuration was enhanced by the adsorption of AgNPs in the presence of creatinine on the PPy film. The SPR reflectivity upon the injection of the mixed solution on the PPy thin film increased with increasing creatinine concentration in the linear range from 10 to 1000 mu M. As a comparison, performances of the creatinine sensor with three SPR sensor systems, i.e. only PPy film, PPy film with AgNPs, and PPy film with aggregated AgNPs, were studied. The SPR sensor with aggregated AgNPs was improved approximately four times compared with the substrate without aggregated AgNPs, and the limit of the detection was 0.19 mu M. The proposed method is potentially useful for clinical applications. (C) 2019 The Japan Society of Applied Physics

DOI： 10.7567/1347-4065/ab4a94

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Other Link： http://iopscience.iop.org/article/10.7567/1347-4065/ab4a94/pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

In this study, transmission surface plasmon resonance (TSPR) signal of a silver-coated Cytop grating/glass slide substrate was investigated in combination with a hyperspectral imaging technique. The TSPR excitation peaks, corresponding to surface plasmon (SP) dispersion modes of +2 (-SP+2) and -1 (+SP-1), were simultaneously observed. The TSPR signal of -SP+2 mode at the visible light region was further enhanced by increasing Cytop thickness. A 2-time stronger in TSPR intensity of the developed substrate than that of conventional silver-coated polycarbonate grating substrate was observed. Since the structure of the substrate was the silver film bound by Cytop and water that had similar dielectric constants, this enhancement was due to a long-range SP resonance effect. TSPR hyperspectral image of developed substrate while injecting different concentrations of ethylene glycol solutions into a five-microchannel assembled to the substrate were recorded and TSPR hyperspectra were then plotted to acquire the sensitivity of this technique. This technique gave a sensitivity of 315.0 nm RIU-1. According to the sensitive changes of TSPR hyperspectral image to the refractive index of an environment, this technique showed high potential with respect to further development of sensing devices based TSPR imaging system. (C) 2019 The Japan Society of Applied Physics

DOI： 10.7567/1347-4065/ab48c9

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Other Link： http://iopscience.iop.org/article/10.7567/1347-4065/ab48c9/pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

We demonstrate self-assembly of fluorescent polymer nanospheres on a nanostructured azobenzene molecular thin film, and evaluate optical near-field excitation of aligned nanospheres. Nanogratings on azo thin film optically fabricated utilizing standing evanescent waves were used for an alignment layer of nanospheres. After dropping and air-drying a solution of nanospheres, the nanospheres were aligned along the grooves of nanograting. The variations in distribution of nanospheres were observed for a choice of grating shape and dispersing solvent of nanospheres. The size ordered alignment of nanospheres was found by using spin coating. To evaluate the fundamental processes of optical near-field excitation of the nanospheres, the emission light from the fluorescent nanospheres periodically aligned on azo grating was observed. The angular distribution of emission lights at a prism side of the angles larger than critical angle was confirmed, which correspond to the near-field optical excitation mediated by evanescent waves radiated near nanospheres. (C) 2019 The Japan Society of Applied Physics

DOI： 10.7567/1347-4065/ab4cfd

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Other Link： http://iopscience.iop.org/article/10.7567/1347-4065/ab4cfd/pdf

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© 2019, © 2019 Taylor & Francis Group, LLC. In this study, the effect of periodic patterned micro/nanostructures on the active layers of thin-film organic photovoltaics (OPVs) was investigated to improve the device performance. The patterned active layer structures were fabricated by a nanoimprinting technique using different templates, including compact disc recordable (CD-R), Blu-ray disc recordable (BD-R), nanowell arrays, nanodot arrays, and honeycomb structures. The OPVs consisted of Al/nanostructured P3HT:PCBM/PEDOT:PSS/ITO. Compared with a flat reference OPV, all the micro/nanostructured OPVs exhibited higher performances, originating from enhanced light absorption due to light scattering and surface plasmon excitation at the patterned Al/P3HT:PCBM interfaces.

DOI： 10.1080/15421406.2019.1651073

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© 2019, © 2019 Taylor & Francis Group, LLC. Silver nanoprisms (AgNPrs) have unique optical phenomena due to their localized surface plasmon resonance that results in the extinction of light from the visible to the near-infrared spectral region. In this study, we propose the colorimetric determination of silver nanoprisms in microchannels using a smartphone camera. Image acquisition was performed by capturing an image of the colloidal solution of the silver nanoprisms in the microchannel using the transmitted light. Red, green, and blue chromaticity levels were extracted from the recorded images for further quantification of the silver nanoprisms. This technique was employed for the detection and colorimetric determination of hydrogen peroxide (H2O2). Good linearity between the change in the green chromaticity level and concentration of hydrogen peroxide was observed for values from 10 to 300 μM with an R2 value of 0.9670. We anticipate that the developed methodology for the quantification of silver nanoprisms and hydrogen peroxide by monitoring the change in color in the images of transmitted light will enhance the development of simple, rapid, and reliable detection systems for quality control in the production of silver nanoprisms as well as in chemical sensor applications.

DOI： 10.1080/00032719.2019.1586913

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DOI： 10.1166/jnn.2019.16704

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DOI： 10.29026/oea.2019.190010

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Plasmonic nanostructures can be used to control the photoluminescence properties of various emitting materials. In this work, an efficient plasmon-induced energy transfer (quenching) was investigated. The luminescence intensity of gold quantum dots (AuQDs) was controlled by the localized surface plasmon resonance of silver nanoprisms (AgNPrs). The quenching was modulated by the degree of spectral overlap between the photoluminescence band of AuQDs and the dipole plasmon resonance of AgNPrs. Furthermore, an in situ controlled quenching effect of AuQDs using an oxidative etching reaction of AgNPrs by hydrogen peroxide (H2O2) was demonstrated. This technique was further developed for application as a H2O2 sensor. This system was capable of detecting 1 nM H2O2 in an aqueous solution.

DOI： 10.1007/s11468-019-01006-8

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© 2019 The Japan Society for Analytical Chemistry. Silver nanoprisms (AgNPrs) have a unique localized surface plasmon resonance, resulting in strong absorption and scattering within the visible light region. In this work, we propose image acquisition from colloidal solutions of AgNPrs using a combination of transmitted and scattered light. The developed measurement technique could be carried out by separately recording transmitted and scattering images of the solutions, using a mobile device camera prior to a calculation of the empirical absorption value (IA). The IA value of green for AgNPrs solutions was found to be in agreement with the absorption spectra obtained using a conventional spectroscopic technique. This technique was utilized for the quantifications of hydrogen peroxide and glucose. Good linearities between ΔIA and those typical analytes were observed. The limit of detection for the typical biosensor of glucose was 19.8 μM. As such, we expect the methodology herein developed for hydrogen peroxide and glucose determinations by means of monitoring the color change of transmitted and scatting images from solutions to contribute to the development of simple, rapid, and reliable detection systems to be further applied to biochemical analysis and clinical diagnosis, as well as to household biosensor applications.

DOI： 10.2116/analsci.18P412

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© 2019 American Chemical Society. In this study, we demonstrate a simple and efficient method to fabricate miniature surface plasmon resonance (SPR) sensor chips by using confined sessile drop technique. A liquid optical adhesive (NOA 61) was dropped on the circular flat surface of cylindrical substrates made of poly(dimethylsiloxane) (PDMS). The formation of hemispherical optical prisms was accomplished by taking advantage of the sharp edges of cylindrical PDMS substrates that prevented the overflow of liquid NOA 61 at the edge of substrates. The size of the hemispherical optical prisms can be controlled by changing the diameter of the cylindrical PDMS substrates. After UV curing, the SPR sensor chips were obtained by the deposition of 3 nm thick chromium and 47 nm thick gold on the flat side of the prisms. The fabricated miniature SPR sensor chips were then mounted on a three-dimensional-printed flow cell to complete the microfluidic SPR sensor module. The miniature SPR sensor chips provided a comparable sensitivity to the conventional high-refractive-index glass SPR chips. To demonstrate the detection capability of nanometer-sized materials, we applied the miniature microfluidic SPR system for monitoring the deposition of layer-by-layer ultrathin films of poly(diallyldimethylammonium chloride)/poly(sodium 4-styrenesulfonate) and for detecting human immunoglobulin G.

DOI： 10.1021/acsami.9b01617

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DOI： 10.1587/transele.2018OMP0004

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Other Link： https://dblp.uni-trier.de/db/journals/ieicet/ieicet102c.html#JuagwonLSKSOB19

Publishing type：Research paper (scientific journal)  

© 2019, © 2019 Taylor & Francis Group, LLC. Gas sensing by using the transmission surface plasmon resonance (T-SPR) technique was demonstrated. Polyacrylic acid (PAA)/5-nm-thick gold/40-nm-thick silver/polycarbonate grating substrate structure (Sensor A) responded to ammonia; however, it exhibited a strong humidity dependence. Polyvinyl alcohol (PVA)/5-nm-thick gold/40-nm-thick silver/polycarbonate grating substrate structure (Sensor B) as the sensing material was also prepared and it mainly responded to humidity. The T-SPR properties of Sensors A and B were observed simultaneously by a stacking arrangement that enabled us to obtain the responses by using a single spectrophotometer. The ammonia concentration under various humidity conditions could be accurately obtained by simultaneous measurement of Sensors A and B.

DOI： 10.1080/15421406.2019.1645466

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© 2019 The Royal Society of Chemistry. Light management allows enhancement of light harvesting in organic solar cells (OSCs). In this paper, we describe the investigation of OSCs enhanced by the synergistic effect of gold quantum dots (AuQDs) and localized surface plasmons, obtained by blending a AuQD layer and plasmonic gold nanoparticles (AuNPs) in a hole-transport layer (HTL). Different AuQDs emitting blue, green, and red fluorescence were examined in this study. The OSCs were demonstrated to comprise an ITO-coated glass substrate/AuQDs/PEDOT:PSS:AuNPs/P3HT:PCBM/Al structure. The UV-visible spectra, current density versus voltage characteristics, impedance spectra, and incident photon-to-current efficiency of the fabricated devices were evaluated. The results showed an enhancement of photovoltaic efficiency achieved as a result of the increase in short-circuit current density (Jsc) and power conversion efficiency (PCE) in comparison with those of the reference OSCs. The best synergistic effect was found with OSCs consisting of a green-emitting AuQD layer and a HTL containing AuNPs, resulting in the highest improvement in PCE of 13.0%. This indicated that the increase in light harvesting in the developed devices was induced by extended light absorption in the UV region resulting from absorption by the AuQD layer and emission of visible fluorescence from the AuQD layer to the photoactive layers. Moreover, the localized surface plasmon effect of AuNPs, which also contributed to an increase in light trapping in the proposed OSCs, was enhanced by the effect of the AuQDs.

DOI： 10.1039/c8na00119g

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© 2018 The Royal Society of Chemistry. Surface plasmon resonance (SPR) originates from collective oscillation of electron density and associated electromagnetic field at a metal/dielectric interface. Reflection SPR, which includes prism-coupling and grating-coupling methods, and transmission SPR (TSPR) have been developed for use in a smartphone sensing platform. The strength of this approach relies on the SPR phenomenon: the strong electromagnetic oscillation of electrons that can occur at a metal/dielectric interface and is highly sensitive to changes in the localized dielectric on the metal surface. The observable SPR signals are strong enough to detect with a simple camera. By combining the SPR phenomenon with the high performance of a smartphone camera, smartphone-based SPR platforms have been developed for use in on-site and remote detection of biomedical and environmental samples, point-of-care devices, and practical use in household devices. This review gives an overview of smartphone-based SPR platforms in both reflection SPR and TSPR configurations, the design of the devices, and the typical setup used to acquire spectroscopic information and SPR images, as well as providing some examples of their use in the analysis of chemical and biological samples.

DOI： 10.1039/C8AY01561A

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Copyright © Materials Research Society 2018. A transmission surface plasmon resonance image (TSPRi) obtained with a plasmonic grating structure was investigated in combination with a smartphone camera. A substrate of a gold-coated CYTOP grating/glass slide showed the TSPR excitation wavelength of 675 nm at the incident light angle of 30°. The TSPRi acquired from a smartphone camera assembled with liquid crystal tunable filters corresponded with spectroscopic results. The sensitivity of this technique was 282/RIU. Due to changes in the sensitivity of the TSPRi intensity to the refractive index of the environment, this technique can be further developed for portable devices for sensor applications.

DOI： 10.1557/mrc.2018.141

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer New York LLC  

In this study, transmission surface plasmon resonance (TSPR) of a silver-coated elastomeric grating substrate was tuned via mechanical stretching. The wavelengths of TSPR excitation peaks, corresponding to surface plasmon dispersion modes of + 1 and − 1, were simultaneously observed. The TSPR excitation wavelength was dramatically shifted up to 80 nm when the strain of the substrate reached 13.3%. The fine control of TSPR properties of the silver-coated elastomeric grating substrate has potential applications in mechanically tunable band pass filters, optical sensors, etc.

DOI： 10.1007/s11468-018-0768-5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Cambridge University Press  

Detection of chlorpyrifos (CPF) using a surface plasmon resonance (SPR)-enhanced photoelectrochemical sensing system is demonstrated in this study. The presence of CPF was detected based on an increase in the short-circuit photocurrent when a sample is injected into the electrolyte at different concentrations. The short-circuit photocurrent signal was enhanced by both localized SPR of the gold nanoparticles and by the effects of grating-coupled propagating SPR. Using the hybrid SPR-enhancement system, CPF detection was achieved at concentrations as low as 7.5 nM. The proposed technique of leveraging a multifunctional photovoltaic effect can be used for a variety of sensing applications.

DOI： 10.1557/mrc.2017.131

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Japan Society of Applied Physics  

An electrochemically synthesized graphene oxide (GO)/poly(3,4-ethylenedioxythiophene) (PEDOT)/poly(styrene sulfonate) (PSS) thin film-based electrochemical surface plasmon resonance (EC-SPR) sensor chip was developed and employed for the detection of human immunoglobulin G (IgG). GO introduced the carboxylic group on the film surface, which also allowed electrochemical control, for the immobilization of the anti-IgG antibody via covalent bonding through amide coupling reaction. The SPR sensitivity of the detection was improved under the control by applying an electrochemical potential, by which the sensitivity was increased by the increment in applied potential. Among the open-circuit and different applied potentials in the range of -1.0 to 0.50 V, the EC-SPR immunosensor at an applied potential of 0.50 V exhibited the highest sensitivity of 6.08 × 10-3 mL μg-1 cm-2 and linearity in the human IgG concentration range of 1.0 to 10 μg mL-1 with a relatively low detection limit of 0.35 μg mL-1. The proposed sensor chip is promising for immunosensing at the physiological level.

DOI： 10.7567/JJAP.57.02CA07

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Taylor and Francis Inc.  

Enhancement of photoisomerization of Azobenzene dye Chicago Sky Blue 6B (CSB) was attempted using long-range surface plasmon resonance (LRSPR). The CSB film was prepared on a grating substrate with metal film for LRSPR, and its transmission light property was investigated before and after white light irradiation for photoisomerization. The transmission light was markedly changed by irradiation of p-polarized white light, and the change was attributed to photoisomerization of CSB induced by LRSPR which accompanies an intense electric field. Furthermore, the effect of LRSPR was significant compared to standard SPR.

DOI： 10.1080/15421406.2018.1456146

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DOI： 10.1002/app.45641

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER ADVANCED TECHNOLOGY  

Transmission surface plasmon resonance (TSPR) is an unusual extraordinary optical transmission that is more transparent at certain wavelengths than expected by classical theory. The three main plasmonic structures that providing this phenomenon are nanohole arrays, diffraction gratings, and nanoslit arrays. This extraordinary optical transmission phenomenon is produced as a result of surface plasmon excitations. The shifting in TSPR responses upon changing of dielectric environment at the surface of a metallic film was observed. After TSPR was discovered from metallic nanohole arrays in 1998, the number of papers about this topic rapidly increased. In the 20 years since, TSPR has been utilized to improve the detection limits, sensitivity, selectivity, and dynamic range of biosensing devices, resulting in them having greater potential for commercialization. This review gives a broad overview of the TSPR phenomenon, the development of this technique, and the typical experimental setups used to acquire TSPR signals; it also describes how they are applied in the field of research into biosensors.

DOI： 10.1016/j.bios.2017.07.069

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A biosensing platform based on the covalent attachment of biomolecules on electropolymerized carboxylated conducting polymers, poly(3-aminobenzoic acid) and poly(3-pyrrole carboxylic acid), were developed for the selective simultaneous detection of two biomolecules using electrochemical-surface plasmon resonance (EC-SPR) spectroscopy. The surface morphology of the developed biosensors was studied by scanning electron microscopy and atomic force microscopy. The EC-SPR dual biosensor was developed for the label-free, simultaneous, and selective detection of glucose and human immunoglobulin G (IgG). A change in current density was clearly observed after the injection of glucose, whereas a change in SPR reflectivity was clearly observed after the injection of human IgG. The present work demonstrates the potential of this biosensing platform for real sample analysis in the future. (C) 2017 Wiley Periodicals, Inc.

DOI： 10.1002/app.45641

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Gold quantum dots (AuQDs) are employed as photosensitizers in organic thin-film solar cells (OSCs) to improve their photoelectric conversion properties. Three types of AuQDs with different fluorescence emission wavelengths are used: blue (B-AuQDs), green (G-AuQDs), and red (R-AuQDs). AuQDs are loaded into the poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) thin-film layer of OSCs. UV-vis spectra, atomic force microscope images, current density-voltage characteristics, and impedance spectra of the fabricated devices are measured for the three aforementioned types of AuQDs. All types of AuQDs improve the photoelectric conversion properties, and the G-AuQD-loaded OSCs exhibit the best improvement, exhibiting an efficiency increase of 10% compared with OSCs without the AuQDs. The fluorescence/photo-sensitization of the AuQDs plays an important role in the enhancement of the OSCs. Finite-difference time-domain simulations indicate increased electric field intensity due to a small degree of AuQDs aggregation.

DOI： 10.1002/ppsc.201700133

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The localized surface plasmon resonance of in-plane dipole plasmon resonance of silver nanoprisms was used to facilitate transmission surface plasmon resonance (TSPR). The TSPR signal was detected by a camera coupled with liquid crystal tunable filters. This technique was further utilized for the multiple detection of hydrogen peroxide. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2017.04.037

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

In this work, we studied the performance enhancement of organic thin-film solar cells (OSCs) originating from the presence of diffraction gratings on the surface of the active layer. Two types of diffraction gratings, periodic gratings (Blu-ray disc recordable: BD-R) and quasi-random gratings (Blu-ray disc: BD), were employed as master templates for grating structures. The grating structures were introduced to the surfaces of poly(3-hexylthiophene) (P3HT):phenyl-C-61-butyric acid methyl ester (PCBM) films, which were the active layers of the solar cells. The addition of the grating structures led to an increase of light absorption in the absorption region of P3HT:PCBM induced by light scattering. Furthermore, the grating-coupled surface plasmon resonance generated additional light absorption peaks. With illumination of non-polarized light at a normal incident angle, the short-circuit current densities of the BD-R and BD solar cells improved by 11.05% and 10.6%, respectively. Efficiency improvements of 19.28% and 3.21% were also observed for the BD-R and BD devices, respectively. Finally, the finite-difference time-domain simulation results revealed an enhanced electric field in the P3HT: PCBM layer, especially in the BD-R OSC devices.

DOI： 10.1039/c6nr09951c

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

Analysis of NH3 gas under various humidity conditions was conducted using a waveguide surface plasmon resonance (SPR) sensor with dual sensing parts. Two pairs of Ag films/sensing polymer films were prepared separately on a waveguide core of BK-7 slide glass. Poly(acrylic acid) (PAA) and poly(vinyl alcohol) (PVA) were used as sensing materials. A white light was guided through the core by illuminating the substrate edge, and the SPR property was investigated by observing the output light spectrum. The thicknesses of PAA and PVA films were adjusted to induce SPR at different wavelengths. PAA exhibited remarkable response against NH3 gas, but it also exhibited a strong dependence on humidity. In contrast, PVA responded to humidity but hardly responded to NH3 gas below 20 ppm. The dual sensing would allow us to conduct precise NH3 measurements under various humidity conditions.

DOI： 10.2116/analsci.33.443

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Institute of Electronics, Information and Communication Engineers  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

In this study, we demonstrate improved photovoltaic properties in inverted organic thin-film solar cells by simultaneous excitation of grating-coupled surface plasmons and grating-coupled waveguide modes on gold grating surfaces. The cell consists of a glass-ITO substrate/titanium dioxide/poly(3-hexylthiophene-2,5-diyl): phenyl-C61-butyric acid methyl ester/poly(3,4-ethylenedioxythiophene): poly( styrene sulfonate)/gold structure. The grating structures were fabricated on P3HT: PCBM layers using a nanoimprinting technique with a PDMS stamp. The grating-structured PDMS stamps were fabricated using a DVD-R grating template with a grating pitch, Lambda, of 740 nm. Reflectivity measurements made using p-polarized light clearly indicate 2 types of excitation modes, i.e., surface plasmons and waveguide modes, while s-polarized light produces only waveguide modes. Incident photon-to-current efficiency measurements exhibited increased photocurrent wavelengths corresponding to the wavelengths of surface plasmon excitations and waveguide mode excitations. Through the simultaneous excitation of surface plasmons and waveguide modes, short-circuit photocurrents in the grating-structured cells exhibited an improvement of up to 11% in the solar cells, leading to an efficiency increase of 16%.

DOI： 10.1039/c6cp06931b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

The microfluidic transmission surface plasmon resonance (MTSPR) constructed by assembling a gold-coated grating substrate with a microchannel was employed for biosensor application. The transmission surface plasmon resonance spectrum obtained from the MTSPR sensor chip showed a strong and narrow surface plasmon resonance (SPR) peak located between 650 and 800 nm. The maximum SPR excitation was observed at an incident angle of 35 degrees. The MTSPR sensor chip was employed for glucose sensor application. Gold-coated grating substrates were functionalized using 3-mercapto-1-propanesulfonic acid sodium salt and subsequently functionalized using a five-bilayer poly(allylamine hydrochloride)/ poly(sodium 4-styrenesulfonate) to facilitate the coupling/ decoupling of the surface plasmon and to prepare a uniform surface for sensing. The detection limit of our developed system for glucose was 2.31 mM. This practical platform represents a high possibility of further developing several biomolecules, multiplex systems, and a point-of-care assay for practical biosensor applications. (C) 2017 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.56.017002

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Transmission light property due to surface plasmon resonance (SPR) was investigated for glass substrate/500-nm-thick fluoropolymer (CYTOP) with a grating structure/thin metal film/mixed solution of water and glycerol system. Transmission light peaks were observed due to grating-coupled SPR, with a remarkable peak intensity when pure water exists as an ambient dielectric. CYTOP exhibits a refractive index close to that of water, and the remarkable peak intensity was attributed to long-range SPR. The monitoring of polyelectrolyte layer-by-layer film deposition using transmission light was also investigated.

DOI： 10.1007/s00289-016-1683-6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

In this study, urchin-like gold nanoparticles (UL-AuNPs) are used in the fabrication of organic thin-film solar cells (OSCs). UL-AuNPs, which have gold nanothorns on their surface, enhance light accumulation by acting as light-trapping materials. This is due to the enhanced electric field and light scattering attributed to the nanothorns on the surface of the nanoparticles. UL-AuNPs were incorporated into a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) thin-film layer of organic thin-film solar cells (OSCs). UV-vis spectra, atomic force microscopy (AFM) images, current density versus voltage properties, and the impedance spectra of the fabricated devices were recorded at various concentrations of UL-AuNPs. We found that the efficiency of the OSCs with UL-AuNPs was not only higher than that of a reference cell without nanoparticles but also higher than that of OSCs with spherical AuNPs. Finite-difference time-domain (FDTD) simulation indicated that the electric field around the UL-AuNPs increased due to the presence of nanothorns.

DOI： 10.1039/c6cp02373h

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Fluorescent nanodroplets of liquid crystal (LC) were generated by the electrospray deposition of LC solvent containing rhodamine 6G (Rh6G) dye molecules. The shape and density of the nanodroplets strongly depended on the concentration of LC diluted with ethanol solution. The fluorescent spectra from the Rh6G molecules in LC nanodroplets were obviously blue-shifted compared with the LC films of the bulk state. Furthermore, the LC nanodroplets were dispersed on a metallic nanograting formed by optically modifying an azobenzene thin-film layer under the metallic film. The nanodroplets were size-selectively aligned on the metallic nanograting. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.02BB09

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Improvement of the on/off ratio in carrier-generation type organic field-effect transistors with pentacene and MoO3 layers was attempted using oblique deposition. A MoO3 layer was formed only between the gold (Au) source and the drain electrodes, and devices with a MoO3 layer evaporated under various deposition angles were fabricated. A formation of a MoO3-free area is expected adjacent to the source or drain electrode by the oblique deposition. The off-current in the device decreased and the on/off ratio was increased with increasing deposition angle, and we achieved a fabricating device with a MoO3 layer having high on/off ratio, almost the same as that of the device without the MoO3 layer. From those results, we deduced that charge-transfer (CT) complexes at the pentacene/MoO3 interface formed a high-conductive path for the off-current, and the off-current was reduced by the formation of a highly-resistive MoO3-free area between electrodes. Therefore, controlling the CT complex layer formation by patterning the MoO3 layer can reduce the amount of off-current and improve the on/off ratio. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.02BB06

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Applied Physics  

DOI： 10.7567/JJAP.55.02BB09

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

In this work, inverted organic thin film solar cells on grating-structured electrode were fabricated by a nanoimprinting technique. First, a Ti02 layer was deposited on an ITO/glass slide substrate. Then, the blend of poly(3-hexylthiophene-2?5-diyl) (P3HT) and phenyl-C61 -butyric acid methyl ester (PCBM) with mass ratio of 1:0.8 dissolved in L2-dichlorobenzene was spin-coated on the TiO: layer. The grating pattern was created on the P3HT:PCBM layer by nanoimprinting technique using PDMS stamp. PDMS grating pattern template was created also by nanoimprinting using DVD-R grating template with the grating pitch of 740 nm. Poly(3.4ethylenedioxythiophene):poly(styrene sulfonate) (PEDOS:PSS) was then spin-coated on the patterned PHT:PCBM layer. Finally, Au was deposited on the PEDOT:PSS as a top electrode by vacuum evaporation technique. The fabricated device showed higher short-circuit photo-current as compared to standard flat solar cells. Transmitted-surface plasmon resonance (T-SPR) measurements showed that the surface plasmon excitation is one of the factors for an enhancement of the device performance. Furthermore, polarized UV-vis. absorption measurements exhibited that the P3HT molecules aligned in vertical direction (in-plane) to the grating groove direction after the nanoimprinting.

DOI： 10.1541/ieejfms.136.690

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：HINDAWI PUBLISHING CORP  

In this study, we demonstrate a long-range surface plasmon resonance (LR-SPR) biosensor for the detection of whole cell by captured antigens A and B on the surface of red blood cells (RBCs) as a model. The LR-SPR sensor chip consists of high-refractive index glass, a Cytop film layer, and a thin gold (Au) film, which makes the evanescent field intensity and the penetration depth longer than conventional SPR. Therefore, the LR-SPR biosensor has improved capability for detecting large analytes, such as RBCs. The antibodies specific to blood group A and group B (Anti-A and Anti-B) are covalently immobilized on a grafting self-assembled monolayer (SAM)/Au surface on the biosensor. For blood typing, RBC samples can be detected by the LR-SPR biosensor through a change in the refractive index. We determined that the results of blood typing using the LR-SPR biosensor are consistent with the results obtained fromthe agglutination test. We obtained the lowest detection limits of 1.58 x 10(5) cells/ml for RBC-A and 3.83 x 10(5) cells/ml for RBC-B, indicating that the LR-SPR chip has a higher sensitivity than conventional SPR biosensors (3.3 x 10(8) cells/ml). The surface of the biosensor can be efficiently regenerated using 20mM NaOH. In summary, as the LR-SPR technique is sensitive and has a simple experimental setup, it can easily be applied for ABO blood group typing.

DOI： 10.1155/2016/1432781

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Taylor and Francis Inc.  

A quartz-crystal-microbalance (QCM) and surface-plasmon-resonance (SPR) hybrid sensor was prepared, and the sorptions of water and ethanol vapors to polyvinyl alcohol (PVA) films were observed in situ. The shift of the SPR wavelength depended on the PVA film thickness as well as the sorbed vapor. It was estimated to be due to the film swelling induced by the vapor sorption and the relationship between the film thickness and the penetration depth of evanescent wave.

DOI： 10.1080/15421406.2015.1097002

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

A novel method was proposed to judge degradation/health of lithium-ion batteries using the capacitance that was estimated from the real-time voltage and current characteristics of the batteries. It is thought that the capacitance of lithium ion batteries decreases with degradation because of undesirable components formed on the electrodes that are the main cause of the degradation. As the lithium ion batteries are active, the capacitance was evaluated from the differential equation, ΔQ/Δv = I/(Δv/Δt) = i/(dv/dt), using the voltage and the current characteristics during the charging or the discharging. The capacitances of the commercial LIBs with different SOHs
100, 92 and 88% were estimated during the charging and the discharging using the equation. The average capacitance in the specific voltage region of the batteries was directly proportional to the state of health. Therefore, the proposed measurement is thought to be a useful method for judging degradation of lithium-ion batteries.

DOI： 10.1541/ieejfms.135.624

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

We fabricated organic field-effect transistors (OFETs) having a thin layer of molybdenum trioxide (MoO3), a Lewis acid, and evaluated their electrical characteristics. The insertion of a thin MoO3 layer reduces the on/off ratio but improves the apparent mobility of the charge carriers. To identify the dominant mechanism responsible for this effect, we characterized devices having a 69-nm-thick pentacene layer with a 1-nm-thick MoO3 layer either between the gold source and the drain electrodes or only directly under these electrodes. The former device exhibited a low on/off ratio, whereas the latter device exhibited an on/off ratio comparable to those of conventional pentacene OFETs without a thin MoO3 layer, suggesting that the formation of charge-transfer (CT) complexes immediately above the conduction channel is the critical mechanism. CT complexes at the pentacene/MoO3 interface immediately above the conduction channel contribute to the formation of an effective channel for off-currents as well as drain currents. Moreover, we also attempted to improve the on/off ratio by using a cloth to rub the surface of a thin MoO3 layer immediately above the conduction channel to create what we believe to be a profile with abrupt changes in height in the direction of the drain current conduction in OFETs. Consequently, it was found that such a rubbed MoO3 layer had a surface with a scratched pattern, and the on/off ratio of the OFET was improved, indicating that controlling the CT complex formation by patterning a MoO3 layer can reduce the off-current in OFETs having a pentacene/MoO3 active layer.

DOI： 10.1587/transele.E98.C.98

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

A quartz-crystal-microbalance (QCM) and surface-plasmon-resonance (SPR) hybrid sensor was prepared, and the depositions of polymer electrolytes layer-by-layer (LbL) films were observed in situ. The estimated thicknesses obtained from the QCM method were different from those obtained from the SPR method. This was estimated to be caused by film swelling and water contained in the film.

DOI： 10.1587/transele.E98.C.136

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

The fabrication of a grating structure formed by a solid-state electrolyte layer on a dye-TiO2 film by the nanoimprinting technique using a polydimethylsiloxane (PDMS) stamp and its application in photoelectric conversion devices are described. The PDMS grating pattern is imprinted from blu-ray disc recordable. A silver electrode was deposited on the patterned solid-state electrolyte layers. Surface plasmon resonance (SPR) excitation was observed in the fabricated solar cells by irradiation with white light. The photoelectric conversion properties were measured to study the effect of the two types of SPR excitations, i.e., the propagating surface plasmon on the Ag grating surface and the localized surface plasmon from the Au nanoparticles on TiO2.

DOI： 10.1587/transele.E98.C.104

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：HINDAWI PUBLISHING CORPORATION  

The electropolymerization process and doping/dedoping properties of poly(3-aminobenzoic acid) (PABA) thin films on gold-coated commercial BD-R and DVD-R grating substrates were simultaneously studied by the combination of electrochemical technique and transmission surface plasmon resonance (TSPR) spectroscopy. The optical property as a function of the applied potentials and time dependence during electropolymerization were studied. The obtained TSPR wavelength scan spectra after electropolymerization showed that the maximum wavelength slightly shifted to longer wavelength indicating the increase of film thickness. In addition, the change during construction of PABA-based immunosensor for label-free detection of human immunoglobulin G can be observed.

DOI： 10.1155/2015/650516

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Water-stable poly(acrylic acid) (PAA) fibers were fabricated on flat gold thin films via an electrospinning technique. The obtained fibers were then used to construct long-range surface plasmon resonance (LR-SPR) biosensors. Because LR-SPR spectroscopy has a greater evanescent field intensity and penetration depth than conventional surface plasmon resonance (SPR) spectroscopy, the increased surface area of the PAA fibers within the surface plasmon evanescent field was efficiently utilized for biosensor applications. The water-stable electrospun PAA fibers were obtained by adding beta-cyclodextrin as a crosslinker, followed by thermal treatment at 150 degrees C for 40 min. In addition, the layer-by-layer deposition of poly(diallyldimethylammonium chloride) and PAA ultrathin films on the electrospun PAA fibers functionalized their surfaces and further increased their water-stability by increasing the number of active carboxylic acid groups. Fiber surfaces were then successfully activated for the construction of immunosensors for the detection of human immunoglobulin G. Therefore, the present study demonstrates the potential of electrospun fibers for LR-SPR biosensor applications. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2014.07.121

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

We demonstrate the multiple plasmonic effect on the photocurrent properties of photoanodes containing Ag or Au nanoparticles (NPs) loaded onto titanium dioxide film (Ag-TiO2 or Au-TiO2) on Au grating surfaces. Ag-TiO2 or Au-TiO2 nanocomposite particles are prepared by a flame spray pyrolysis route. The structures and morphologies of the prepared products are characterized by high-resolution transmission electron microscopy. The Ag-TiO2 or Au-TiO2 composite NPs are deposited by spin coating onto the Au grating surfaces. The photoanode electrode is a layered structure of blu-ray disc-recordable grating substrate/Au/Ag (or Au)-TiO2/dye/electrolyte/indium-tin oxide. The plasmonic effect is induced when Ag or Au NPs are located within the propagating surface plasmon (SP) field on the Au grating surface. The short-circuit photocurrent is increased by exciting the grating-coupled propagating SP on the Au gratings and is further enhanced by positioning the Ag or Au NPs within the grating-coupled SP field. Copyright (C) 2014 John Wiley & Sons, Ltd.

DOI： 10.1002/sia.5577

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

In this study, we achieved an enhancement of the transmission surface plasmon resonance (T-SPR) intensity by depositing silver nanoparticles (AgNPs) onto a gold grating substrate. The T-SPR spectrum of the gold grating substrate with AgNPs showed a strong and narrow SPR peak located between 650 and 800 nm; the maximum SPR excitation was observed at a 35A degrees angle of incidence. We controlled the distance between the gold grating surface and the AgNPs by using layer-by-layer (LbL) ultrathin films of poly(diallydimethylammonium chloride) (PDADMAC) and poly(sodium 4-styrenesulfonate) (PSS) to study the distance dependence of the coupling effect between the AgNPs and the gold grating substrate. The distance-dependent T-SPR response of peak position and intensity showed distinctive changes when the intermediate layer was 10 bilayers (similar to 17 nm) thick. The strongest coupling surface plasmon excitation between the AgNPs and the gold grating substrate was obtained at this layer spacing. Furthermore, we explored the potential of the developed system as a switchable pH sensor. The T-SPR spectrum sensitively changed as the pH switched from acidic (pH 2) to alkaline (pH 12) conditions by the swelling/shrinking of the poly(allylamine hydrochloride) (PAH)/PSS LbL film, respectively, which was deposited between the AgNPs and the gold grating.

DOI： 10.1007/s11468-014-9695-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

We fabricated plasmonic gold nanoparticle (AuNP)-TiO2 nanocomposite films and measured the photocurrent that originates from the water-splitting reaction catalyzed by the AuNP-TiO2 nanocomposite photo-electrocatalytic (PEC) electrode. The localized surface plasmon resonance (LSPR) of the gold nanoparticles affected the generation of photocurrent by TiO2 upon illumination with visible light. Electrochemical impedance spectroscopy (EIS) revealed that the improvement in the photocurrent generation originates from an enhancement in electron-hole pair generation induced by the SPR of the plasmonic gold nanoparticles rather than the extension of the electron lifetime. Moreover, we introduced a novel method to enhance the photocurrent of TiO2 by a multiple plasmonic effect, i.e., LSPR of plasmonic gold nanoparticles and the grating-coupled propagating SP on a gold grating. We fabricated the AuNP-TiO2 nanocomposites on a gold-coated Blu-ray disc recordable (BD-R). The enhancement of the photocurrent due to the combination of LSPR and the grating-coupled SP was investigated.

DOI： 10.1039/c4cp03885a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：HINDAWI PUBLISHING CORPORATION  

Au-loaded TiO2 nanoparticles were synthesized by the modified sol-gel method together with the impregnation method. Anatase phase of TiO2 was obtained in all samples with an average particle size of 20 nm. For the enhancement of DSSCs, the dye-sensitized solar cells composed of the ITO/Au-loaded TiO2/N-719/electrolyte/Pt were fabricated. Au-loaded TiO2 films were deposited by using squeegee method. Finally, the fabricated cells were studied upon an irradiation of solar light to study the performance. The fabricated cell with up to 1.0 mol% Au-loaded TiO2 could enhance the performance by localized surface plasmon effect and scattering property.

DOI： 10.1155/2014/865423

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

In this study, we present an electrochemically controlled surface plasmon resonance (EC-SPR) biosensor to detect adrenaline on poly(2-aminobenzylamine) (P2ABA) thin films. The P2ABA thin films are stable and display electroactivity in a neutral PBS solution. Specific detection of adrenaline was performed on P2ABA thin films because the benzylamine groups in the P2ABA structure could specifically react with adrenalines. Adrenaline was detected in real time by EC-SPR spectroscopy, which provides an EC-SPR reflectivity change on the P2ABA thin film upon adrenaline injection. The measured responses were quite different from those for uric acid and ascorbic acid, which are major interferences in adrenaline detection. The electrochemically applied potential facilitates the specific detection of adrenaline. In addition, the detection of adrenaline on the P2ABA thin films was investigated by a quartz crystal microbalance technique. The detection limit for adrenaline at open circuit potential was 10 pM. The present study provides a useful information on the detection of adrenaline on the P2ABA thin films. Copyright (c) 2013 John Wiley & Sons, Ltd.

DOI： 10.1002/sia.5301

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Poly(2-aminobenzylamine)/single wall carbon nanotube (P2ABA/SWNTS) thin films were fabricated for the detection of UA by using electrochemical surface plasmon resonance spectroscopy (EC-SPR) technique. The suspension of 0.01% wt of carboxylated SWNTSs was assembled on the polymer film because of the electrostatic and van der Waals interactions between the COOH and NH 2. The P2ABA/SWNTS thin film formation on gold electrode was studied by EC-SPR technique. In this work, uric acid was detected by EC-SPR in PBS buffer comparing with the interference response with ascorbic acid. EC-SPR uric acid sensor using P2ABA/SWNTS thin film can be applied for the detection of uric acid in urine. © 2013 Taylor and Francis, LLC.

DOI： 10.1080/15421406.2013.803887

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Electropolymerization of carboxylated conducting polymer/carbon nanotubes (CNTs) composites thin films has been studied by in situ electrochemical-surface plasmon resonance (EC-SPR) spectroscopy. Two derivatives of benzothiophene, thianaphthene-2-carboxylic acid and benzothiophene-2-propionic acid, composited with CNTs were electropolymerized in an acetonitrile with the potential range between 0 and 1.2V at scan rate of 20mV/s. The obtained films were characterized by in situ EC-SPR spectroscopy, UV-vis absorption spectroscopy, and atomic force microscopy. It was found that CNTs can improve properties of polymer/CNT composites films. Moreover, the obtained thianaphthene-2-carboxylic acid film can be further used for construction of immunosensor for detection of human IgG.

DOI： 10.1080/15421406.2013.803890

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

The functionalized pyrrole copolymers were fabricated by electropolymerization of pyrrole (Py) and functionalized pyrrole monomers, pyrrole-3-carboxylic acid (P3C) and 4-(3-pyrrole) butyric acid (PBA). The electrochemical behavior and doping/dedoping properties of the obtained copolymer thin films were investigated by cyclic voltammetry (CV) in neutral phosphate-buffered saline (PBS) solution. Moreover, the functionalized pyrrole copolymer films were characterized by UV-vis absorption spectroscopy and atomic force microscopy (AFM). The obtained copolymer thin films showed good stability and electroactivity in neutral PBS solution. The presented functionalized pyrrole copolymer thin films may possess potential applications to study in various systems of the biosensors.

DOI： 10.1080/15421406.2013.804775

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

We developed a novel technique for increasing the sensitivity of transmission surface plasmon resonance (T-SPR) signals. T-SPR spectroscopy was performed by irradiating, with white light, a gold grating substrate whose surface was nanostructured by growing gold nanoparticles (AuNPs). AuNPs were grown directly on the substrate surface by alcohol reduction and their growth was observed at various stages by UV-visible spectroscopy and standard Kretschmann-type SPR spectroscopy. For comparison, normal gold film with smooth surface was examined under similar condition. The T-SPR results show a possibility of hybrid excitation of both localized and propagating surface plasmon. Significantly, T-SPR spectra of the gold grating substrate obtained during AuNP growth show stronger and narrower peaks in the range 650-800 nm. The maximum T-SPR excitation was at an incident angle of 35 degrees. A layer-by-layer system of 5,10,15,20-tetrakis (1-methyl-4-pyridinio) porphyrin tetra(p-toluenesulfonate) molecules and sodium copper chlorophyllin molecules was used to verify the enhancement of the developed system. We believe that the AuNPs/Au grating for T-SPR devices will provide enhanced signals for detecting nanometer order materials and for high-sensitive sensor applications.

DOI： 10.1007/s11468-012-9400-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

In this study, we fabricated a novel quartz-crystal-microbalance (QCM)/optical-waveguide hybrid sensor. An in situ observation of a lead phthalocyanine (PbPc) thin-film deposition was conducted during vacuum evaporation, and the effectiveness of the sensor was demonstrated. The film thickness was obtained from the QCM frequency, and the optical absorption of the film was observed by optical waveguide spectroscopy using part of the QCM substrate without the electrode. The film absorption depends on the polarization direction, substrate temperature and deposition rate, owing to aggregate formation. The thickness dependence of the absorption property was also investigated. (C) 2013 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.52.05DC20

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

We report enhanced photocurrent properties of dye/Au-loaded titanium dioxide (TiO2) films on Au gratings. Au-loaded TiO2 nanopowders were first synthesized by a modified sol-gel method and then prepared by the impregnation method. We also fabricated dye-sensitized solar cells, which were composed of Au grating/Au-TiO2/TMPyP-SCC LbL (20 bilayers)/electrolyte/ITO substrates. Short-circuit photo-current measurements showed that Au-loaded TiO2 with grating-coupled surface plasmon excitation can enhance the short-circuit photocurrentof the fabricated cells.

DOI： 10.1587/transele.E96.0.385

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Imprinted solution-processible gold nanoparticle (AuNP) grating films were fabricated for use as a grating-coupled surface plasmon resonance (SPR) excitation substrate. The imprinted AuNP grating pattern, which consists of a 1.72 mu m grating pitch, was fabricated on flat glass substrates by imprinting AuNP on silicon grating templates. In this study, the SPR measurements were carried out on an SPR device in the grating-coupling configuration with a He-Ne laser (lambda = 632.8 nm) as the excitation source, and multimode surface plasmon excitations were observed upon irradiation with white light. SPR excitation of our substrate was observed at the incident angle of 47.1 degrees. For SPR measurements using white light irradiation, multimode surface plasmon excitation resulting from several diffraction orders was observed in the wavelength region of 500-850 nm. The surface plasmon dispersion branches were calculated to obtain the diffraction order in this region. SPR excitation of the imprinted AuNP grating substrate was further studied by fabrication of a layer-by-layer ultrathin film of iron containing bis(terpyridine) polymer (Fe(II)-BTP) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). A shift of the SPR excitation spectrum was observed when the ultrathin film was deposited on the imprinted AuNP grating surface. Thus, this substrate should be a useful SPR substrate in a variety of applications such as photoelectric conversions and sensors. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2012.07.003

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

Insertion of a thin layer of the Lewis acid molybdenum trioxide (MoO3) improves the apparent mobility of charge carriers in organic field-effect transistors (OFETs). In order to identify the dominant mechanism responsible for this, we characterized devices having a bottom pentacene (70 - z nm)/MoO3 (1 nm)/top pentacene (z nm) structure and those having pentacene (69 nm)/MoO3 (1 nm) only under the gold source and drain electrodes. The former devices exhibited large drain currents (I-DS)and mobilities, regardless of the z value. Moreover, the latter devices exhibited comparable I-DS and mobilities to those of conventional pentacene OFETs, suggesting that the formation of CT complexes just above the conduction channel is the critical mechanism. Carriers generated by dissociation of CT complexes at the pentacene/MoO3 interface contribute to the formation of an effective channel and the apparent mobility. (C) 2012 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.51.101601

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Surface plasmon resonance (SPR)-enhanced optical transmission is actively controlled by an electrochromism of conducting polymer thin films. Polyaniline and poly(3,4-ethylenedioxythiophene) thin films are deposited on a thin gold grating surface. SPR-enhanced optical transmission is demonstrated by irradiating white light on the conducting polymer thin filmgold grating surface and detecting the transmitted light from the back side. The transmission SPR system is combined with an electrochemical setup to manipulate the resonance. The wavelength of the sharp peak in the transmission light spectra is tuned by electrochemical doping/dedoping of the conducting polymer thin films. The present study of controllable SPR-enhanced optical transmission should provide novel active plasmonic devices such as active bandpass filters or biosensors.

DOI： 10.1002/adfm.201200373

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

In this study, we describe the combination of transmission surface plasmon resonance (TSPR) an electrochemical techniques for the application to biosensors with conducting polymers. Electropolymerization was employed to construct poly(pyrrole-3-carboxylic acid) (PP3C) film on a gold coated grating substrate using pyrrole-3-carboxylic acid (P3C) monomer solution in 0.5 M H2SO4. In situ electrochemical transmission surface plasmon resonance (EC-TSPR), 1 measurements were carried out to study the kinetic and electroactivity properties of PP3C film. Immobilization of antihuman IgG on the activated surface and the binding process of human IgG and antihuman IgG in neutral solution could be detected in situ by EC-TSPR measurement. The surface modification steps on the PP3C layer led to an increase in intensity of the transmission peak. The performance, sensitivity, and utility of EC-TSPR spectroscopy showed obvious advantages for the detection of binding process with the simple experimental setup, and could be applied to the study of biomolecular interactions in various systems.

DOI： 10.1021/am300970m

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SCIENCE PRESS  

Optical near-field excitations were investigated on the basis of molecular alignment control of liquid crystals (LCs) on an optically rewritable nanostructure of photoreactive molecular thin films. Twisted nematic (TN) cells of LC molecules were constructed utilizing ITO substrates with 260 nm gratings of an azobenzene molecular thin film, fabricated using standing evanescent waves. The polarization changes of light transmitted through the TN cells, which were due to the alignment changes of LC molecules locally rubbed by the azobenzene nanogratings, were observed. Furthermore, we demonstrated local plasmon excitation of Au nanowires deposited on the azobenzene nanogratings using oblique vacuum evaporation, a phenomenon that produced strong anti-optical absorption spectra. The modulation of the local plasmon resonance in metallic nanowires decorated with LC molecules was confirmed.

DOI： 10.1007/s11433-012-4754-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We fabricated a hybrid sensor utilizing quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) spectroscopy. We confirmed its effectiveness by observing QCM frequency shifts and SPR wavelength changes for two processes: deposition of various transparent polymer thin films and moisture sorption. For thin-film deposition, the relationship between the QCM frequency and SPR wavelength was found to depend on the refractive index of the film material. For moisture sorption, the direction of SPR wavelength shift depended on the film thickness. This was estimated to be caused by film swelling and decrease in refractive index induced by moisture. (C) 2012 The Japan Society of Applied Physics

DOI： 10.1143/APEX.5.036603

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this review, we introduce a variety of surface sensitive techniques for the study of organic thin films, and applications to organic devices. These studies include surface plasmon emission light, organic thin film transistors, combination of quartz crystal microbalance and optical waveguide spectroscopy, evaluation of alignment of liquid crystal molecules at surfaces, and biosensor applications.

DOI： 10.1587/transele.E94.C.1824

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Ridge optical waveguides (OWGs) of fluorinated polyimides were deposited on a quartz crystal microbalance (QCM), and a hybrid sensor employing the OWG spectroscopy and the QCM technique was prepared. A polyvinyl alcohol (PVA) film with CoCl2 was deposited on the OWG, and humidity sensing characteristics were investigated. White light was entered into the waveguide and the output light spectra was observed. The output light intensity markedly changed because of the chromism of CoCl2 by humidity sorption. During the output light measurement, the QCM frequency was monitored simultaneously. The humidity dependences of the QCM frequency and output light were also investigated in a range from 10% to 70%. Furthermore, the response to hydrofluoroether (HFE) was observed, and the change in the output light was hardly observed because CoCl2 does not exhibit chromism in HFE sorption.

DOI： 10.1587/transele.E94.C.1851

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

In this study, we demonstrate the fabrication of grating-coupled surface plasmon resonance (SPR) enhanced organic thin-film photovoltaic cells and their improved photocurrent properties. The cell consists of a grating substrate/silver/P3HT:PCBM/PEDOT:PSS structure. Blu-ray disk recordable substrates are used as the diffraction grating substrates on which silver films are deposited by vacuum evaporation. P3HT:PCBM films are spin-coated on silver/grating substrates. Low conductivity PEDOT:PSS/PDADMAC layer-by-layer ultrathin films deposited on P3HT:PCBM films act as the hole transport layer, whereas high conductivity PEDOT:PSS films deposited by spin-coating act as the anode. SPR excitations are observed in the fabricated cells upon irradiation with white light. Up to a 2-fold increase in the short-circuit photocurrent is observed when the surface plasmon (SP) is excited on the silver gratings as compared to that without SP excitation. The finite-difference time-domain simulation indicates that the electric field in the P3HT: PCBM layer can be increased using the grating-coupled SP technique.

DOI： 10.1021/am200304x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN PHYSICAL SOC  

In this paper, the driving mechanism of carrier-generated organic field-effect transistors (OFETs) with pentacene and vanadium pentoxide (V(2)O(5)) layers is discussed. In this study, large on-currents were observed in an OFET with a 35-mm V(2)O(5) layer. Devices with aluminum (Al)/pentacene/V(2)O(5)/Al layer structures were also prepared. These devices exhibited a large current density in spite of their high carrier injection barriers between each layer and the Al electrodes. Moreover, new absorption bands corresponding to the radical cation absorption of pentacene were observed within the absorption spectrum of the pentacene and V(2)O(5) mixed layers. It was inferred that the charge transfer (CT) complexes that formed at the interface between the pentacene and V(2)O(5) layers were dissociated by the applied gate voltage and that the generated holes contributed to driving the OFETs.

DOI： 10.3938/jkps.58.1402

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SCIENTIFIC PUBLISHERS  

In this report, we demonstrate a novel way to tune the fluorescence property of electrospun conjugated polymer fibers. The basic strategy is to use a soluble precursor polymer with gold nanoparticies for electrospinning, which is then cross-linked by applying potential cycles in an electrochemical cell. Electroactive carbazole units in electrospun precursor polymer fibers were converted to conjugated polymer fibers. Since the conjugated polymer fibers can be formed, the fluorescence from the conjugated polymer fibers can be tuned by the rate of the conversion and doping of the fibers. Furthermore, the quenching of the fluorescence, which overlaps with the plasmon band of the gold nanoparticles, was observed. The quenching of the fluorescence properties of the fibers was dependent on the amount of gold nanoparticles inside the fibers.

DOI： 10.1166/jnn.2011.3648

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

A half-cylindrical BK-7 prism/dielectric film with a grating/Ag film/fluorescent polymer film structure was prepared, and its surface plasmon (SP) excitation property was investigated. It was confirmed experimentally that SP excitations are possible in this structure by using prism and grating couplings. The SP excitation property depended on the direction of the grating vector. Furthermore, intense photoluminescence was observed when the SPs were simultaneously excited at the Ag/polymer interface by prism coupling and at the Cytop/Ag interface by grating coupling.

DOI： 10.1587/transele.E94.C.196

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Multiple surface plasmon resonance (SPR) sensors were prepared on a waveguide, and vapor sensing was carried out. A BK-7 slide glass was used as a waveguide core, and three pairs of Ag films (50 nm)/polymer films with various thicknesses were prepared separately on the waveguide. White light was input from the substrate edge, and the spectrum of the output light was observed. Discrete SPR dips can be observed in the output light spectra by selecting the dielectric constant and the thickness of the polymer film, which govern the SPR condition. The sensors with poly(vinyl alcohol) as sensing material were prepared and the water vapor sorption properties were investigated. Furthermore, polyisoprene, poly(vinyl carbazole), poly(methyl methacrylate), and perfluorinated polymer were used as sensing materials, and the detection of various vapors was carried out.

DOI： 10.1143/jjap.50.01bc15

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

An electrochemically controlled surface plasmon resonance (SPR) immunosensor for the detection of human immunoglobulin G (IgG) has been developed using poly(pyrrole-3-carboxylic acid) (PP3C) film. In this work, a pyrrole-3-carboxylic acid monomer was used for electropolymerization of a PP3C film on a gold-coated high-refractive-index glass slide. In situ electrochemical (EC)-SPR spectroscopy was performed to study the kinetic property and electroactivity property of the PP3C film. Moreover, ultraviolet-visible (UV-vis) spectroscopy was performed to characterize the PP3C film. Finally, the immunosensor-based PP3C film was constructed. The carboxylic acid surface of the PP3C film was activated for the immobilization of anti-human IgG. The immunosensor electrode was used for probing the binding reaction of anti-human IgG/human IgG with several concentrations of human IgG at different constant applied potentials. The probe immobilization and immunosensing process were in situ monitored by EC-SPR technique. The sensitivity of the sensor was improved by controlling the morphology of the PP3C film by applying the potential. (C) 2011 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.50.01BK02

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

In this paper, we demonstrate the fabrication of grating-coupled surface plasmon resonance (SPR)-enhanced dye-sensitized solar cells (DSSCs) and their increased short-circuit current properties. DSSCs consisted of a grating substrate/gold/TiO2/dye/electrolyte/indium-tin oxide structure. Blu-ray disc recordables were used as diffraction grating substrates on which gold films were deposited by vacuum evaporation. TiO2 films were prepared on the gold/grating substrates by an electrophoretic deposition technique. 5,10,15,20-Tetrakis (1-methyl-4-pyridinio) porphyrin tetra (p-toluenesulfonate) and sodium copper chlorophyllin layer-by-layer ultrathin films were deposited as the dye layer on the TiO2 films. SPR excitation was observed in the fabricated cells upon irradiation with white light. Up to 4.5-fold increase in the short-circuit photocurrent was observed when the surface plasmon (SP) was excited on the gold gratings as compared with that without SP excitation. Finite-difference time-domain simulation indicated that the electrical field in the dye layer could be increased using the grating-coupled SP technique.

DOI： 10.1039/c1jm12935j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

In this Article, we present a novel method to detect adrenaline on poly(3-aminobenzylamine) (PABA) ultrathin films by electrochemical-surface plasmon resonance (EC-SPR) spectroscopy. We prepared a PABA film, which specifically reacts with adrenaline, on a gold electrode by electropolymerization of 3-aminobenzylamine. The specific reaction of benzylamine within the PABA structure with adrenaline was studied by XPS, UV-vis spectroscopy, and EC-SPR techniques. Adrenaline was detected in real time by EC-SPR spectroscopy, which provides simultaneous monitoring of both optical SPR reflectivity and electrochemical current responses upon injecting adrenaline into the PABA thin film. The number of changes in both current and SPR reflectivity on the injection of adrenaline exhibited the linear relation to the concentration, and the detection limit was 100 pM. The responses were distinctive to those for uric acid and ascorbic acid, which are major interferences of adrenaline.

DOI： 10.1021/la1034992

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

In this paper, we demonstrate photocurrent generation from nanostructured layer-by-layer (LbL) ultrathin films consisting of chromophores and single-walled carbon nanotubes (SWNT). We fabricated 5,10,15,20-tetrakis(1-methy1-4-pyridinio)porphyrin tetr (p-toluenesulfonate) (TMPyP)-SWNT/sodium copper chlorophyllin (SCC)-SWNT LbL film from noncovalently adsorbed composites. SWNT were dissolved in water-soluble cationic TMPyP and anionic SCC, and the resulting solutions were used for electrostatic LbL multilayer fabrication. The solubility of SWNT in water was studied by UV-vis absorption spectroscopy. The composites were highly dispersed owing to the pi-pi interactions. The fluorescence spectroscopy measurements showed efficient quenching of TMPyP and SCC fluorescence, which was due to the interaction with SWNT. In situ surface plasmon resonance spectroscopy during the LbL multilayer fabrication indicated a stepwise increase in reflectivity, implying the successive formation of nanostructured hybrid ultrathin films. Cyclic voltammetry revealed that the electroactivity of the hybrid film was enhanced by the incorporation of SWNT. The composite LbL film electrode exhibited an enhancement of photocurrent compared to a TMPyP/SCC (no SWNT) film electrode, suggesting efficient charge separation and electron transfer in the system.

DOI： 10.1021/jp103121m

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

An electrochemically controlled surface plasmon resonance (SPR) immunosensor based on carboxylated polyaniline was constructed for detecting human immunoglobulin G (IgG) without using further labeled molecules. The carboxylated polyaniline, poly(3-aminobenzoic acid) (PABA), was prepared by electropolymerization of its monomer, 3-aminobenzoic acid (ABA), on a gold-coated high-refractive-index glass slide that was also used as a working electrode for the electrochemical system. The kinetic properties during electropolymerization were monitored in situ with electrochemical-surface plasmon resonance (EC-SPR) spectroscopy. The obtained PABA film, which was used to construct the immunosensor, showed electroactivity in neutral phosphate-buffered saline solution. The carboxylic acid surface of the PABA film was then activated to immobilize anti-human IgG. Finally, the immunosensor electrode was used to probe the binding reaction of anti-human/human IgG with various concentrations of human IgG at different constant applied potentials. The immobilization and binding reaction processes were controlled and also studied in situ by EC-SPR spectroscopy. The binding process at different applied potentials was studied and fitted using the Freundlich model. The surface morphology of the films after the immobilization of anti-human IgG was studied by atomic force microscopy. (c) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2010.03.031

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Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/15421401003609764

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Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejfms.130.129

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

In this report, we demonstrate a convenient method of fabricating single-walled carbon nanotubes/organic semiconductor hybrid ultrathin multilayers using a layer-by-layer self-assembly approach. Single-walled carbon nanotubes were solubilized by water-soluble cationic alcian blue pyridine variant and anionic copper phthalocyanine-3,4&apos;,4 &apos;&apos;,4&apos;&apos;&apos;-tetrasulfonic acid tetrasodium salt, which were then utilized for electrostatic layer-by-layer multilayer fabrication. The solubilization ability of single-walled carbon nanotubes was studied in water by UV-vis absorption spectroscopy. The composites were highly dispersed owing to the pi-pi interactions. In situ surface plasmon resonance spectroscopy during the layer-by-layer multilayer fabrication indicated a stepwise increase in reflectivity, indicating the successive formation of nanostructured hybrid ultrathin films. Cyclic voltammetry revealed that the electroactivity of the hybrid film was enhanced by the incorporation of single-walled nanotubes. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2009.09.052

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Language：English   Publishing type：Part of collection (book)   Publisher：World Scientific Publishing Co.  

The research is reviewed on the attenuated total reflection (ATR) method utilizing surface plasmon (SP) excitations at the interface between metal and dielectric ultrathin films, that is, the surface plasmon resonance (SPR) method. The ATR method is quite useful for evaluation of the dielectric ultrathin films and applications to sensors and plasmonic devices. Emission lights due to SP excitations are observed through the prism in the Kretschmann configuration for the ATR method, when metal films on the prism or organic films with metal films on the prism are directly irradiated from air by a laser beam, that is, reverse irradiation. The emission lights depend on the surface roughness of the films and are also related to the photoluminescence of organic molecules. The properties and applications of the SP emission lights are described. Among the SP excitation methods, one of the most well known techniques is a prism coupling technique based on the ATR configuration, while a grating coupling technique can be widely used for the sensing or plasmonic devices. The grating coupling excitation method is also described.

DOI： 10.1142/9789814322492_0012

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Language：Japanese   Publishing type：Research paper (scientific journal)  

We fabricated electrospun poly (vinylalcohol) (PVA) fibers using a copper wire electrode in Teflon capillary tube, and the SEM images were observed. The apparatus in this method is reasonable, and needed volume of polymer solution and distance between the electrodes can be largely reduced compared to conventional method. The wire electrode tip position in the capillary tube is also important in this method and should be close to the polymer solution surface. © 2010 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejfms.130.219

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

In this work, we demonstrate multimode surface plasmon (SP) excitations by white light irradiation on metallic diffraction grating/plastic substrates. Recordable compact discs were used as the diffraction grating substrates on which silver films were deposited by vacuum evaporation. Since the grating pitch (1.6 mu m) was larger than that of diffraction gratings commonly used for the excitation of SPs, multimode SP excitations due to several diffraction orders were observed simultaneously in the wavelength region from 400 to 800 nm. The obtained SP excitations were then compared with the calculated SP dispersion on the grating. The multimode SP excitations were further studied on spin-coated poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) thin film/silver grating substrates. An increased photoluminescence intensity due to SP excitations was observed on MEH-PPV/silver grating surfaces. (C) 2010 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.49.01AE02

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

In this study, we report on the evaluation of tilt angles of liquid crystal (LC) molecules near the surface of SIO2 alignment layers and in the whole cell when constant voltages are applied. A LC molecule, 4-cyano-4'n-pentylbiphenyl, was used in this study. The LC cell consisted of Au (50nm) / SiO2 (30nm) /LC (3 μm)/ SiO2 (30nm) / Au (100nm) system. SiO2 alignment layers were obliquely evaporated on both Au surfaces. Surface plasmon resonance and guided waveguide excitation modes in attenuated total reflection configuration were used to monitor the alignment property of LC molecules adjacent to the surface and the bulk in the LC cell. In the ATR angular scan properties, the theoretical fittings agreed well with the experimental data on the assumption of simplified 5 LC layers model. The profile of the tilt angles from the surface to inside the cells was obtained by the theoretical fitting. In comparison with the internal bulk region, LC molecules near the surface required higher voltages to change their tilt angles toward vertical direction. As demonstrated in this report, this technique should provide the useful information to understand the interfacial phenomena for LC displays. © 2010 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejfms.130.193

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

Polymer fibers were prepared by an electrospinning method utilizing a copper wire electrode in a capillary tube. The morphology of electrospun poly(vinyl alcohol) (PVA) fibers was observed, and was found to be dependent on the wire electrode tip position in the capillary tube, the concentration of the polymer solution, the distance between the electrodes, and the applied voltage. By using the wire electrode, the experimental setup is simple and the distance between the electrodes and the applied voltage can be easily reduced. Furthermore, the preparation of poly(3-hexylthiophene) (P3HT) fibers was carried out. P3HT fibers were successfully prepared by mixing poly(ethylene oxide) (PEO) in P3HT solution. Orientation control was also carried out by depositing the fibers on a rotating collector electrode, and the alignment of the P3HT: PEO fibers was confirmed. Anisotropy of the optical absorption spectra was also observed for the aligned fibers. (C) 2010 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.49.04DK24

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

In this study, we report the evaluation of the tilt angle of liquid crystal (LC) molecules near the surface of SiO2 alignment layers and in the whole cell when AC and/or DC voltages are applied. The LC molecule 4-cyano-4'-n-pentylbiphenyl was used. The LC cell consisted of a Au (50 nm)/SiO2 (30 nm)/LC (3 mm)/SiO2 (30 nm)/Au (100 nm) system. Surface plasmon resonance (SPR) spectroscopy and optical waveguide spectroscopy (OWS) in an attenuated total-reflection configuration were used to monitor the alignment properties of LC molecules. From the SPR/OWS angular scan properties, the profile of the tilt angle from the surface to inside the cell was obtained. Furthermore, the effect of space-charge polarization on the LC alignment properties was observed from the SPR kinetic properties. As demonstrated in this report, this technique should provide useful information for understanding the interfacial phenomena in LC displays. (C) 2010 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.49.04DK22

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

In this study, stab and ridge optical waveguides (OWGs) made of fluorinated polyimides were deposited on a quartz crystal microbalance (QCM), and hybrid sensors using OWG spectroscopy and the QCM technique were prepared. Polyvinyl alcohol (PVA) film with CoCl(2) was deposited on the OWGs, and the characteristics of humidity sensing were investigated. A prism coupler was used to enter a He-Ne laser beam (lambda = 632.8 nm) to the slab OWG. The output light intensity markedly changed due to chromism of the CoCl(2) as a result of humidity sorption, and this change was dependent on the incident angle of the laser beam to the slab OWG. During the measurement of output light, the QCM frequency was simultaneously monitored. The humidity dependence of the sensor with the slab OWG was also investigated in the range from 15 to 85%. For the sensor with the ridge OWG, white light was entered by butt-coupling, and the characteristics of humidity sensing were investigated by observing the output light spectrum and the QCM frequency. (C) 2009 Published by Elsevier B.V.

DOI： 10.1016/j.tsf.2009.07.059

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The attenuated total reflection (ATR) and emission light properties utilizing surface plasmon (SP) excitations were measured for the electrochemical change of poly(3-hexylthiophene-2,5diyl) (P3HT) thin films in-situ. The SP emission light could detect the SP excited by molecular luminescence of P3HT. The ATR and SP emission light properties were observed for the doped-dedoped states of P3HT thin film. The ATR and SP emission light properties were remarkably changed with the electrochemical doping and dedoping. The SP emission light also decreased by decrease of the molecular luminescence of P3HT by doping. For the dedoped-state P3HT thin film, SP emission light also increased by increase of the molecular luminescence. The SP emission light excited by molecular luminescence can be controlled by the control of doping-dedoping state. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2009.07.083

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOCIETY APPLIED PHYSICS  

Organic field-effect transistors (OFETs) with copper phthalocyanine (CuPc) and vanadium pentoxide (V(2)O(5)) films were fabricated (top-contact electrode/V(2)O(5)/CuPc/SiO(2)/Si/gate electrode structure), and their electrical properties were investigated. The drain current increased due to the insertion Of V(2)O(5) layer, and it was considered to be due to a formation of charge transfer complex between V(2)O(5) and CuPc. The ON/OFF ratio of the OFETs was higher than that of previously reported OFETs with a top-contact electrode/CuPc/V(2)O(5)/SiO(2)/Si/gate electrode structure. The off-current of the OFETs in this study was maintained small so that few carriers would contribute to the current conduction in the off-state. (C) 2009 The Japan Society of Applied Physics

DOI： 10.1143/APEX.2.071502

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Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/15421400902946103

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/15421400902946103

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS  

Organic electroluminescent device (OLED) was fabricated using a vacuum evaporation method and thermal properties were investigated. The OLED has an indium tin oxide (ITO)/N,N&apos;-Biphenyl-N,N&apos;-bis(3-methylphenyl)-1,1&apos;-biphenyl-4,4&apos;-diamine (TPD)/tris(8-hydroxyquinoline) aluminum (Alq)/lithium fluoride (LiF)/aluminum (AI) structure. An electron-dominant device of Al/Alq/LiF/Al structure, or it hole-dominant device of ITO/TPD/Al structure was also fabricated in order to study the carrier behavior in the OLEDs. The current density versus voltage (J-V) properties with various thickness of organic layers were investigated in both electron- and hole-dominant devices, and the thermal dependence of J-V properties was observed in the devices. At room temperature, conductions in a wide current region were considered to be due to space-charge-limited current for all of the devices. Especially for the Al/Alq/LiF/Al device and the OLED, J proportional to V(m+1) relationships were observed across a wide current region. At low temperature, tunnel currents were estimated for the ITO/TPD/Al device. For the Al/Alq/LiF/Al device and the OLED, J proportional to V(m+1) relationships were observed across a wide current region at low temperature. (C) 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(3): 24-31, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10048

DOI： 10.1002/ecj.10048

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We demonstrate nanofabrication of photoreactive azobenzene molecular thin films using optical migration of molecules induced by local polarization in optical near-fields. Transportation and alignment control of the nanomaterial systems were investigated to modulate the excitation of the optical near-fields. Energy transfers from fluorescent molecules were observed along a planar boundary system of metals and dielectrics. The fundamental processes of tunneling energy that flowed to the metallic layer were evaluated from the angular distribution of scattered light in a far field, corresponding to the angular spectrum of scattered fields, including those of evanescent waves excited near the fluorescent molecules and nanostructures fabricated on azo molecular films.

DOI： 10.1117/12.825955

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this report. we demonstrate electrocatalytic oxidation properties of ascorbic acid at poly(3,4-ethylenedioxythiophene) (PEDOT) thin films in view of their potential application for big-sensing devices. PEDOT thin films were deposited on gold thin films by electropolymerization of EDOT monomer in acetonitrile solvent. In-situ electrochemical-surface plasmon resonance spectroscopy (EC-SPR) was used to detect both electrochemical and optical signals upon an injection of ascorbic acid.

DOI： 10.1093/ietele/e91-c.12.1881

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Attenuated total reflection (ATR) property utilizing surface plasmon (SP) excitation was investigated for BK-7 prism/MgF2/Ag film/fluorescent organic dye film structure. In the structure, it is expected that SPs are excited at MgF2/Ag and Ag/dye film interfaces by Otto and Kretschmann configurations, respectively. In the experimental ATR curve, reflection dips for the SP excitations at the interfaces could be detected. Furthermore. SP emission lights were observed by irradiation of Ar ion laser beam from the dye film side. The SP emission light curve with two peaks was observed and it was also considered that the peaks corresponded to the SP excitation of Otto and Kretschmann Configurations. The SP emission light spectra indicated the excited fluorescent dyes induced the SP emission lights. Intense emission light of Otto configuration was observed in this sample.

DOI： 10.1093/ietele/e91-c.12.1883

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this study, attenuated total reflection (ATR) utilizing surface plasmon (SP) excitation and SP emission lights were observed for the adsorption of polystyrene (PS) spheres and a water-soluble polymer. The PS spheres contained fluorescent dyes and exhibited red fluorescence. The ATR properties indicated film deposition with increasing number of adsorption cycles. The SP emission light induced by the fluorescent dye ill the spheres was also measured. and all increase in the peak intensity, as well as an angle shift. was observed. Furthermore, the SP emission light spectra were investigated at various emission angles. The dispersion relation obtained front the SP emission light almost corresponded to that obtained from the ATR curves.

DOI： 10.1093/ietele/e91-c.10.1663

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Gas sensing properties were investigated using localized surface plasmons (LSPs) and a quartz crystal microbalance (QCM). A thin film of polyvinylalcohol (PVA) and gold colloid (20 ran in diameter) was deposited on the QCM substrate, and the gas responses of the optical absorption of gold colloid LSP and the QCM frequency were simultaneously observed. Vapors of water, ethanol and methylamine in N-2 were detected. The optical absorption spectra changed with the gas adsorption and desorption, and the gas response could be repeatedly observed. Furthermore, the relationship between the QCM frequency and the optical properties depended on the vapor species. Hybrid sensing can be used for detection and discrimination of various vapor adsorptions. (C) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2007.11.110

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

In this study, thin films of poly(vinyl alcohol) (PVA) mixed with 100 nm polystyrene (PS) microspheres were prepared, and changes in attenuated total reflection (ATR) utilizing surface plasmon (SP) excitation due to the adsorption of humidity were investigated. The PS microspheres contained luminescent dyes, and SP emission light due to these dyes was observed. The sample configuration was prism/Ag film (50 nm)/PVA film with sphere. ATR dip and SP emission peak angles shifted with the adsorption and desorption of humidity, and SP emission light intensity changed markedly. Furthermore, kinetic curves were plotted and humidity adsorption responses were repeatedly observed. Finally, the dispersion relations of SPs were obtained from ATR and SP emission light properties.

DOI： 10.1143/JJAP.47.1110

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

Vapor treatments using several organic solvents were carried out for vacuum-evaporated magnesium phthalocyanine (MgPc) thin films. The UV-vis absorption spectra, surface morphologies, and X-ray diffraction patterns were markedly altered by the treatments and depend on the vapor. Furthermore, Au top-contact organic field-effect transistors (OFETs) were fabricated using MgPc films with and without the vapor treatments. The FET with N-methylpyrrolidone treatment did not work, but that with dichloromethane vapor treatment showed a large improvement in the on/off ratio and field-effect mobilities. Ethanol vapor treatment (5 min) also improved the FET characteristics, but long-term treatment (60 min) induced poor performance.

DOI： 10.1143/JJAP.47.484

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

The preparation Of CuYO2 films on quartz glass substrates was carried out through the solution method using copper and yttrium nitrates as sources. Firstly, dip-coated films on the quartz glass substrates were annealed in air, and then annealed again under nitrogen flow. Continuous films were formed on the substrate surfaces. The films annealed in air at 900-950 degrees C were almost completely dominated by the Cu2Y2O5 phase, except for slight appearances of CuO and Y2O3. After annealing under nitrogen flow at 900-950 degrees C, the films were almost completely dominated by the CuYO2 phase, except for slight appearances Of Cu2O and Y2O3. The slight appearances of the impurity phases are possibly related to slight variations in the concentration ratio of the copper source to the yttrium source within the dip-coated films. The nitrogen-annealed films, as well as bulk CuYO2, exhibited a green emission band owing to the Cu+ interconfiguration transition from 3d(9)4s(1) to 3d(10) with the Stokes shift, being consistent with the dominant appearance of the CuYO2 phase.

DOI： 10.1143/JJAP.47.588

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

As-deposited films were prepared on sapphire substrates at 500-680 degrees C by alternately sputtering Cu and Al targets in Ar-diluted 02 gas atmosphere. The composition of the as-deposited films corresponded to that of the slightly oxygen-rich region of the CuO-CuAl2O4-Al2O3 system. The films as-deposited at 500 degrees C had an amorphous structure, while the films as-deposited at 680 degrees C had CuAl2O4 phase but no CuAlO2 phase. Annealing at 1050 degrees C in nitrogen flow caused a reduction in the molar fraction of oxygen, i.e., the composition of the annealed films with [Cu]/[Al] approximate to 1 corresponded to CuAlO2. The annealed films were predominated by the CuAlO2 Phase. The preferential orientation of the films toward the c-axis normal to the substrate surface is due to the small lattice mismatch between the rhombohedral [010] of delafossite-type CuAlO2 and the hexagonal [(1) over bar 100] of the sapphire substrate. The annealed films had an absorption edge corresponding to the energy gap of CuAlO2 and exhibited p-type conductivity.

DOI： 10.1143/JJAP.47.592

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：INST ELECTR ENGINEERS JAPAN  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：INST ELECTR ENGINEERS JAPAN  

DOI： 10.1109/ISEIM.2008.4664451

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Investigations on optical and dielectric properties of hybrid ultrathin layer-by-layer (LbL) films of gold nanoparticles (AuNPs) and polyelectrolytes under different pH conditions resulted in surface plasmon resonance (SPR) signal enhancement under attenuated total reflection (ATR) spectroscopy conditions. Theoretical considerations on the basis of the Maxwell-Garnett theory were made to compare with experimental results. LbL films with different layer architectures were fabricated from AuNPs and two polyelectrolytes: poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) on Au and Ag thin film substrates for ATR. UV-vis spectroscopy and SPR spectroscopy were applied to study LbL film growth and monitor SPR shift upon pH switching. The (PAH/AuNPs)(x) multilayers showed an interesting dual-responsive SPR change as a function of pH and distance between AuNP layers and metal film. The addition of (PAH/PSS)(y) layers was found to act as an effective cushion to enhance this SPR response due to the significant swelling/shrinking of the film. In the case of [(PAH/PSS)(y) + (PAH/AuNPs)(x)], both theoretical calculations and experimental results showed that the SPR response can either (a) move toward lower incident angle with a sharp peak shape upon swelling in pH = 2 or (b) shift to a higher angle with a broadened peak shape after contraction in pH = 10. This effect was found to be opposite to what is expected from LbL films made up of the polyelectrolytes alone. Moreover, increasing the distance between AuNPs and the metal films also decouples this enhancement effect. A two-wavelength experiment (red and green lasers) was used to quantitatively demonstrate this SPR response to pH switching. Finally, SPR imaging was employed to monitor the SPR change with pH switching between 2 and 10 on the [(PAH/PSS)(4) + (PAH/AuNPs)(2)] film. Thus, on the basis of the SPR spectroscopic and SPR imaging pH response, a reproducible and stable sensing system can be successfully fabricated with these films.

DOI： 10.1021/jp075986e

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Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/15421400701548266

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Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/15421400701544901

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Cu-Al-O films were prepared on quartz glass substrates at 500-700 degrees C by sputtering the Cu and Al targets alternately on atomic-layer scale under an Ar-diluted O-2 (5-20%) gas atmosphere, and then annealed at 1050 degrees C under a nitrogen atmosphere. The [Cu]/[Al] ratio was controlled by changing the Cu and Al deposition periods. The composition of as-deposited films corresponded to the slightly oxygen-rich region of the CuO-CuAl2O4-Al2O3 system. Films as-deposited at 500 degrees C had an amorphous structure, while films as-deposited at 700 degrees C had CuAl2O4 and CuO phases. After thermal annealing in a nitrogen atmosphere, the composition of the films approached that of the Cu2O-CuAlO2-Al2O3 system line, causing a noticeable appearance of the CuAlO2 phase along with the disappearance of the CuAl2O4 and CuO phases. Cu- and Al-rich annealed films had in addition a Cu2O phase and an amorphous Al2O3 phase, respectively. All annealed films exhibited p-type conductivity. The annealed films with [Cu]/[Al] I had an absorption edge corresponding to the energy gap of CuAlO2. These results indicate that the change in the Cu ion from divalent to monovalent through nitrogen annealing results in the preparation of transparent conductive films dominated by CuAlO2.

DOI： 10.1143/JJAP.46.351

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Organic Electroluminescent device (OLED) was fabricated using a vacuum evaporation method and thermal properties were investigated. The OLED has an Indium Tin Oxide (ITO)/ N,N'-diphenyl-N,N'-bis(3-methylphenyl) 1- 1'biphenyl- 4,4'-diamine (TPD)/ tris- (8-hydroxyquinoline) aluminum (Alq)/ Lithium fluoride (LiF)/ aluminum (Al) structure. An electron dominant device of an Al/ Alq/ LiF/ Al structure, or a hole dominant device of an ITO/ TPD/ Al structure was also fabricated in order to study the carrier behavior in the OLEDs. The current density vs. voltage (J-V) properties with various thickness of organic layers were investigated in the both electron and hole dominant devices, and the thermal dependence of J-V properties was observed in the devices. At room temperature, conductions in large current region were considered to be due to space-charge-limited current for all the devices. Especially, for the Al/Alq/LiF/Al device and the OLED, J∝ Vm+1 relationships were observed across wide current region. At low temperature, tunnel currents were estimated for the ITO/TPD/Al device. For the Al/Alq/LiF/Al device and the OLED, J∝ Vm+1 relationships were observed across wide current region at low temperature.

DOI： 10.1541/ieejfms.127.635

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Molecular aligned naphthacene thins films were fabricated using vacuum evaporation and the rubbing method. The attenuated total reflection (ATR) and emission light properties from surface plasmon (SP) excitation due to molecular luminescence were investigated for these films. The long axis of the rod-like molecule was estimated to align perpendicular to the rubbing direction. The ATR and emission light properties depended on the molecular orientation.

DOI： 10.1093/ietele/e89-c.12.1758

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Organic field-effect transistors (OFETs) with Lewis-acid films were fabricated using copper phthalocyanine (CuPc), and the operating mechanism was studied. These OfETs have active layers of CuPc and vanadium pentoxide (V2O5) as a Lewis-acid film. A large drain current was observed in OFET's with a V2O5 layer for a positive gate voltage, and the mobility of these OFETs was improved compared with OFETs with only CuPc as an active layer. To investigate the operating mechanism, Xray diffraction patterns, UV-vis absorption spectra, and ionization potentials were measured in V2O5 films and CuPc films with and without a co-evaporation Of V2O5. Each characteristic of the CuPc layer changed owing to the introduction Of V2O5 It was considered that a CT complex is formed in the CuPc layer owing to the interaction between CuPc and V2O5 molecules, and contributes to the large drain current and improvement in mobility.

DOI： 10.1143/JJAP.45.8890

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

DIn delafossite-type oxides of CuRxY1-xO2 (R = Eu, Th or Tm) and CuRxCaY1-x-yO2 prepared through the conventional solid state reactions, the lattice constant dependence on the composition implies doping with the Th3+, Eu3+ and Tm3+ cations on the Y3+ site. Noticeable sharp emission lines due to the f-f transitions of Eu3+, Th3+ and Tm3+ are observed at room temperature in CuRxCayY1-x-yO2 as well as CuRxY1-xO2. P-type conductivity of CuRxCayY1-x-yO2 increases with increasing Ca concentration, indicating the increase of hole concentration caused by doping with Ca2+ acceptor cation on the Y3+ site. These results indicate the controllability of the luminescence and conductivity in delafossite-type CuYO2, oxides by co-doping with Eu, Tb or Tm rare-earth cation and Ca acceptor cation on the Y3+ sites. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/pssa.200669568

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Language：English   Publishing type：Research paper (scientific journal)  

In delafossite-type oxides of CuR xY 1-xO 2 (R = Eu, Tb or Tm) and CuR xCa yY 1-x-yO 2 prepared through the conventional solid state reactions, the lattice constant dependence on the composition implies doping with the Tb 3+, Eu 3+ and Tm 3+ cations on the Y 3+ site. Noticeable sharp emission lines due to the f-f transitions of Eu 3+, Tb 3+ and Tm 3+ are observed at room temperature in CuR xCa yY 1-x-y,O 2 as well as CuR xY 1-xO 2. P-type conductivity of CuR xCa yY 1-x-yO 2 increases with increasing Ca concentration, indicating the increase of hole concentration caused by doping with Ca 2+ acceptor cation on the Y 3+ site. These results indicate the controllability of the luminescence and conductivity in delafossite-type CuYO 2 oxides by co-doping with Eu, Tb or Tm rare-earth cation and Ca acceptor cation on the Y 3+ sites. © 2006 WILEY-VCH Verlag GmbH &amp
Co. KGaA.

DOI： 10.1002/pssa.200669568

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Nano-patterns were investigated on azo dye thin films exposed by an interference of evanescent waves propagating on a prism surface. The patterns strongly depended upon polarization of the incident laser beams forming electric field vectors of the evanescent waves in the vicinity of the prism surface. Line structures of surface relief gratings (SRGs) were clearly inscribed by selecting s-polarization of the incident light. The cyclic pattern of the lines was approximately 210 nm that was smaller than a half of the wavelength of the incident laser at 488 nm. Any line patterns were not obtained using p-polarization of the light, but nano-dot patterns were fabricated on azo dye films. This technique based on molecular migration due to evanescent waves is thought to be very useful for nano-device processing and future device applications. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2006.02.054

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Aluminum phthalocyanine chloride (AlClPc) thin films were evaporated and the properties of the AlClPc thin films treated with ethanol vapor were investigated using attenuated total reflection (ATR) and emission light measurements due to surface plasmon (SP) excitations. The optical absorption spectra and surface morphology remarkably changed due to the ethanol-vapor treatment. From the ATR measurement, it was found that the thickness evaluated from the theoretical calculations increases with the treatment of ethanol vapor. The emission lights due to SP were also observed for the samples. The emission light intensity increase with the surface roughness for the incident light with wavelength of 488.0 nm. The current vs. voltage characteristics of the AlClPc thin films before and after the ethanol-vapor treatment were also investigated and it was found that the conduction current was increased by the ethanol-vapor treatment. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2005.07.022

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Top-contact organic field-effect transistors (OFETs) with Lewis-acid films were fabricated using copper phthalocyanine, (CuPc), and the effects of inserted Lewis-acid thin films on electrical properties were investigated. The OFETs have active layers of CuPc and vanadium pentoxide (V2O5) as a Lewis-acid film. Larger drain currents were observed for the OFET with the V2O5 layer than that without the layer. The calculated field-effect mobility of the fabricated OFET was 3.6 x 10(-3) cm(2)/(Vs), where as that of the OFET without the V2O5 layer was 2.5 x 10(-4) cm(2)/(Vs). It was thought that holes and electrons were generated in V2O5 film by gate voltage and the holes were injected into the CuPc layer. The injected holes in the CuPc layer and electrons in the V2O5 layer can contribute to drain current and the apparent high mobility.

DOI： 10.1143/JJAP.45.L99

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Molecular aligned naphthacene thin films were prepared using rubbing method. The attenuated total reflection (ATR) and surface plasmon (SP) emission light properties were investigated. The long axis of the naphthacene molecule was found to be aligned perpendicular to the rubbing direction. The ATR and SP emission light properties depended on the molecular orientation.

DOI： 10.1109/NMDC.2006.4388918

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Delafossite-type oxides of CuTbyY1-yO2, CuEuyY1-yO2, CuCaxTbyY1-x-yO2 and CuCaxEuyY1-x-yO2 have been prepared by solid state reactions. The lattice-parameter dependence on the composition implies substitution of the Tb3+, Eu3+ and Ca2+ cations for the Y3+ site. Noticeable sharp emission lines due to the f-f transitions (D-5(4) -&gt; F-7(J), J = 3-6) of Tb3+ or due to the f-f transitions (D-5(O) -&gt; F-7(J), J = 0-4) of Eu3+ are observed at room temperature. Electrical conductivities of CuCaxTbyY1-x-yO2 and CuCaxEuyY1-x-yO2 are larger than those of CuTbyY1-yO2 and CuEuyY1-yO2, indicating the increase of the hole concentration caused by the substitution of Ca2+ for the Y3+ site. These results indicate the controllability of the luminescence and conductivity in CuCaxTbyY1-x-yO2 and CuCaxEuyY1-x-yO2 delafossite-type oxides by simultaneous substitution of the rare earth Tb3+ or Eu3+ cation and the Ca2+ cation for the Y3+ site. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jpcs.2005.09.065

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Thiophene dendrimer spin-coated films were fabricated and the optical and photoelectric properties were investigated. Absorption edge and peak of photoluminescence (PL) spectra for the film were observed at around 550 and 618 nm, respectively. The excitation spectrum almost corresponded with optical absorption. From the voltage vs. current properties, the Schottky conductions were estimated in the indium tin oxide (ITO)/dendrimer/Al device. Photoelectric properties were also observed and the action spectra of the photocurrent in the device also corresponded with the absorption spectrum. (c) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cap.2004.01.045

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Organic light emitting diodes (OLEDs) with nanostructured ultrathin layers inserted at the interface between electron- and hole-transport layers were investigated. The fundamental structure of the OLEDs fabricated by a vacuum evaporation method was indium-tin-oxide (ITO) anode/copper phthalocyanine (CuPc)/N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine (TPD)/8-hydroxyquinoline aluminum (Alq(3))/LiF/Al cathode. Fullerene (C-60) and rhodamine B (RhB) molecules were used as the nanosutructured ultrathin layers inserted at the interface between the Alq(3) and TPD layers. The electroluminescent (EL) properties have been measured for the OLEDs with C-60 and RhB ultrathin layers and the dependences on the thickness and the position of the inserted layers were examined. For the OLEDs with the C-60 ultrathin layer, the improvements of the drive voltage and EL efficiency were observed. The OLED with the inserted C-60 ultrathin film of a monolayer thickness showed the highest efficiency, which was twice as large as that without C-60 layer. On the contrary, the improvements were not observed for the OLEDs with the RhB ultrathin layer. (c) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cap.2004.01.047

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

Surface plasmon (SP) emission light was observed for a merocyanine (MC) Langmuir-Blodgett (LB) film and an MC/crystal violet (CV) hetero-LB film in the ATR Kretschmann configuration. Intense photoluminescence of CV and quenching of MC were observed due to an energy transfer from MC to CV in the hetero-LB film. SP emission light due to CV was also observed for the MC/CV hetero-LB film. Furthermore, the emission light properties of the MC/CV hetero-LB film did not depend on the polarization direction of excitation light and were considered to be a result of the molecular shape of CV.

DOI： 10.1143/JJAP.44.599

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Fabrication of surface relief gratings (SRGs) on azo dye thin films has been investigated utilizing an interference of evanescent waves. SRGs of approximately 210 nm were inscribed on the photoisomerized azo dye films, that were smaller than a half wavelength of an incidence laser of 488.0 nm. The films were set on a right-angled triangular prism surface and were in the interference of evanescent waves of totally reflected laser beams at the prism surface. The interference at the surface was performed using a laser beam through the one side of the isosceles and the returned beam at the other side of the isosceles where a mirror was set. The SRG patterns of azo dye films due to trans-cis transition of the dyes were observed in situ using an atomic force microscope above the prism surface. (C) 2005 American Institute of Physics.

DOI： 10.1063/1.1857070

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

Delafossite-type CuYO2 and CuY1-xCaxO2 (x &lt;= 0.05) samples exhibited a green-PL-emission band due to the Cu+ interconfiguration transition from 3d(9)4s(1) to 3d(10) at room temperature. With increasing Ca concentration, the Cu+ emission shifted slightly to the. shorter-wavelength side with a slightly weaker emission intensity. This slight change in Cu+ emission property is considered to be caused by the increase in hole concentration within the Cu+ layer arising from the increase in Ca concentration. On the other hand, oxygen-annealed CuYO2 samples exhibited no emissions. The increase in nonradiative relaxation processes in the oxygen-annealed CuYO2 samples is possibly related to structural changes such as orthorhombic distortion during the oxygen annealing. In the photoluminescence of delafossite-type CuY1-yTbyO2 (y = 0.05) at room temperature, no Cu+ emission band was observed, but sharp emission lines were observed. All the emission lines were assigned to the f-f transitions of Tb3+ (D-5(4)-&gt; F-7(J), J = 3-6).

DOI： 10.1143/JJAP.44.765

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MATERIALS RESEARCH SOCIETY  

Emission light due to surface plasmon (SP) excitations has been investigated in Kretschmann configuration of prism/metal thin film/organic dye thin films by means of direct irradiation of a laser beam from air to the films. Emission light through the prism coincided with the resonant conditions of SP excitations in the configuration. It was thought that SPs on the metal surface were excited by luminescence of dye molecules close to the metal surface, and the SPs propagating along the metal surface were converted to the emission light according to the resonant conditions of SPs in the configuration. Intensities and spectra of the SP emission light through the prism strongly depended upon emission angles, nanostructures of dye films, the film thickness and mixture of two kinds of dyes.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：INST ELECTR ENGINEERS JAPAN  

A novel method was performed for optical fabrication of nano-structures on organic photosensitive thin films utilizing evanescent waves on prism surface. The evanescent waves are produced by means of total internal reflection of laser beams on a prism surface and the intensity shows exponential decay from the surface. Nano-patterns of surface relief gratings (SRGs) were inscribed for spin-coated azo dye (congo red) films showing photoisomerization by the evanescent waves. The cycle pattern of the SRG was approximately 210nm that was smaller than a half of the incident laser wavelength of 488 run. In the conventional technique of fabrication of SRGs, it is very difficult to obtain narrower lattices and one can not obtain any smaller lattices of SRGs than a half wavelength of the laser beam. This techniques based on molecular migration due to evanescent waves are thought to be very useful for nano-device processing and future device applications.

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Surface plasmon (SP) emission light has been investigated for rhodamine-B (RB) dye Langmuir-Blodgett (LB) films on silver (Ag) thin film in the attenuated total reflection (ATR) Kretschmann configuration by means of reverse irradiation of a laser beam. Emission light through the prism was clearly observed for the configuration of prism/Ag/LB films corresponding to the resonant excitation conditions for SPs using the reverse irradiation. The intensities of the SP emission light increased with the thickness of the RB LB films. but nonlinear reductions of the SP emission light and photoluminescence (PL) were observed due to nonradiative energy transfer at the very small separations between the RB and Ag films. It is thought that the SPs, that is. two-dimensional optical waves, are excited by PL of the RB dyes on the Ag film and that this phenomenon is very useful for applications utilizing dye molecules on metal thin films.

DOI： 10.1143/JJAP.43.2335

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Alternate layer-by-layer (LbL) films were fabricated using two kinds of copper phthalocyanine (CuPc) dyes and the electrical properties due to NO2 gas adsorption were investigated. Water-soluble CuPc dyes, that is, cationic Alcian blue, pyridine variant (AB) and anionic copper phthalocyanine-3,4',4",4'"-tetrasulfonic acid, tetrasodium salt (CuPcTs) were used for the alternate LbL films. Successive depositions of the CuPc alternate LbL films were confirmed using UV-visible absorption and ellipsometry measurements. The average thicknesses of the AB and CuPcTs monolayers were estimated to be 0.7 nm and 0.4 nm, respectively. The fundamental electrical properties were examined for the CuPc alternate LbL films with Au gap electrodes and the properties in the direction parallel to the surfaces of the LbL films were measured. The conduction currents were considered to be dominated by hopping conduction. The response to NO, gas was also measured and the large increase in conduction Currents due to NO, gas adsorption was observed. The magnitude of the conduction current after 30 min exposure to 100 ppm NO2 gas was 10(3)-10(4) times larger than that in N-2 gas.

DOI： 10.1143/JJAP.43.2311

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Institute of Electronics, Information and Communication Engineers  

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Other Link： http://hdl.handle.net/10191/8848

Language：English   Publishing type：Research paper (scientific journal)  

Photoluminescence and surface plasmon emission light have been investigated in the attenuated total reflection (ATR) Kretschmann configuration. Surface plasmons (SPs), two-dimensional optical waves, were excited when rhodamine-B (RB) dye Langmuir-Blodgett (LB) films on metal thin film were directly irradiated by laser beams in the Kretschmann configuration. Emission light, that is, three-dimensional optical waves through the prism were observed corresponding to the resonant conditions of SP excitations in the configuration. The intensity of the SP emission light was small for the RB LB film with 4 layers, but the intensities increased in proportion to the thickness for the LB films having above 8 layers. Photoluminescence intensities also strongly depended upon the nanostructured separation between the RB LB films and metal thin films. It is thought that the phenomena are very useful for applications utilizing dye molecules on metal and conversion between three- and two-dimensional optical waves. © 2004, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejfms.124.293

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DOI： 10.1080/15421400390264054

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Composition and structure of CuAlO2 films, deposited through the dc-reactive sputtering method using Cu and Al elemental targets and Ar-diluted oxygen gas, were controlled by the Cu and Al deposition periods and the postannealing temperature. The delafossite CuAlO2, films were successfully prepared by the postannealing of the films with [Cu]/[Al] I at temperatures higher than 700 degreesC in the nitrogen atmosphere. In comparison with the optical absorption edge of the CuAlO2 films, those of Cu-rich and Al-rich films sifted to the longer and shorter wavelength regions, respectively. The shifts of the optical absorption edge in the off-stoichiometric films are interpretable to be due to the additional copper oxide or aluminum oxide phase. The resistivity of the high-temperature postannealed films with p-type was in the range of 10 - 10(2) Ohmcm. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/S0022-3697(03)00194-X

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The properties of attenuated total reflection (ATR) and emission due to surface plasmon (SP) excitation were investigated for the alternate layer-by-layer ultrathin films self-assembled on Ag thin films using polycation (poly(diallyldimethylammonium chloride), PDADMAC) and azo-dye (Direct Red 80, DR80). The emission light had peaks at the same angles as the resonant angles of the ATR curves and the shapes of the emission spectra also corresponded to those of the ATR curves, and the emission was considered to be mainly due to the SP excitation mediated by the surface roughness of Ag thin films. The structure of the PDADMAC/DR80 layer-by-layer films was found to change due to the photoisomerization of DR80 molecules by the irradiation of polarized visible light, and the surface roughness of the layer-by-layer films was also found to increase by the irradiation and hardly to change after 5-min irradiation. (C) 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0040-6090(03)00780-6

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Relationships between molecular thin film structure and multiple surface plasmon (SP) excitations at nano-interfaces have been investigated for prism/metal thin film/molecular thin films in the attenuated total reflection Kretschmann configuration. Recently, emission light through the prism that strongly depended upon the emission angles was observed using the reverse irradiation, that is, direct irradiation of a laser beam from air to molecular thin films. Emission light in the reverse irradiation has investigated in detail for organic thin films with various structures. From the dispersion property of the emission spectra at various emission angles, it was estimated that the emission light was caused by excitation of multiple SPs at the nano-interfaces. The emission properties also depended upon the amount of dye molecules, nano-spacing between the metal and dyes, and polarizations of the laser beam. It is thought that the phenomenon is useful for application to new devices utilizing multiple SP excitations. (C) 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0040-6090(03)00783-1

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Ultrathin films containing water-soluble copper (11) phthalocyanine-3,4',4",4'''- tetrasulfonic acid (CuPcTs) and poly(diallyldimethylammonium chloride) (PDADMAC) were fabricated using the electrostatic layer-by-layer deposition technique. UV-vis absorption spectra and ellipsometry measurements suggested successive linear depositions of the bilayers of CuPcTs and PDADMAC. The thickness of the CuPcTs monolayer obtained from the ellipsometry was smaller than the plain size of CuPcTs and the molecule planes were considered and tilted in the film. The surface morphology was also observed using atomic force microscopy. The cyclic votammogram (C-V) of the fabricated films in 0.1 M KCl aqueous solution suggested the oxidation and reduction of the CuPcTs at approximately +0.9 and +0.05 V vs. Ag/AgCl, respectively. UV-vis absorption spectra were observed for the films at applied voltages of +0.9 and 0.0 V in the KCl aqueous solution and electrochromisms were repeatedly observed. (C) 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0040-6090(03)00730-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Polystyrene submicron and micron sphere films were fabricated and the optical properties were investigated using surface plasmon spectroscopy (SPS) and reverse irradiation utilizing the SPS Kretschmann configuration. The diameters of the spheres were 0.1 and 1.0 mum. For the 0.1-mum-sphere films, the dip angles of the SPS curves shifted to higher angles with the amount of spheres in the films. However, for the 1.0-mum-sphere films, the SPS curves did not shift with the amount of spheres which is considered to be due to the change of the effective dielectric constant in the decay length of the evanescent field intensity of surface plasmon. Furthermore, emitted light due to reverse irradiation was also observed as a function of the emitted angle in the Kretschmann configuration. The peak angles of the emitted light almost corresponded to the dip angles of the SPS curves and the emitted light was considered to be due to surface plasmon excitation.

DOI： 10.1143/JJAP.42.2506

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Emission light through a prism has been investigated for prism/silver (Ag) thin film/merocyanine (MC) Langmuir-Blodgett (LB) films in the Kretschmann configuration. Emission light was observed by means of direct irradiation of a laser beam from air to the MC LB films, that is, reverse irradiation. The emission properties coincided with resonant conditions of surface plasmon (SP) excitations in the Kretschmann configuration. Emission due to SP excitations depended upon the position of the MC LB film in the LB hetero films of arachidic acid (C20)MC/C20 on the Ag thin film. The strongest emission was observed at some separation of the MC LB layer from the metal surface. Emission properties were also investigated for the hetero LB films of MC and C20 on aluminum (Al) thin film and for the MC LB films with various thicknesses. It is thought that the phenomenon is useful for application to new devices utilizing multiple SP excitations.

DOI： 10.1143/JJAP.42.2511

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Organic light-emitting diodes (OLEDs) with a nanostructured fullerene (C-60) layer at and near the interface between the electron- and hole-transport layers were fabricated using a vacuum evaporation method. The OLEDs had a fundamental structure of indium-tin-oxide (ITO) anode/copper phtalocyanine (CuPc)/N,N'-dephenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine (TPD)/8-hydroxyquinoline aluminum (Alq(3))/LiF/Al cathode. The electroluminescent (EL) properties have been investigated for the OLEDs with a nanostructured C-60 layer at the TPD/Alq(3) interface and at the different positions in the Alq(3) layer near the TPD/Alq(3) interface. The dependences of the EL properties on the thickness of the inserted C-60 layer and on the position from the interface were examined. The OLEDs with a C-60 monolayer inserted at the TPD/Alq(3) interface showed the highest efficiency.

DOI： 10.1143/JJAP.42.2526

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Taylor and Francis Inc.  

Surface plasmon (SP) excitations have been investigated in the attenuated total reflection (ATR) Kretschmann configuration of prism/metal/organic ultrathin films. Structure and optical properties of organic ultrathin films have been evaluated using the ATR measurement due to SP excitations. Recently, emission light through the prism was observed using direct irradiation of a laser beam from air to the organic films, that is, reverse irradiation. The emission spectra strongly depended upon the emission angles through the prism and were caused by multiple SP excitations. The emission properties also depend upon structure of metal and organic thin films, dye molecules, separation between metal and molecules, molecular interaction, and so on. It is thought that the phenomenon is useful for application to new devices utilizing multiple SP excitations, and nanostructured devices of organic films using multiple SP excitations are described.

DOI： 10.1080/744819014

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Surface plasmon (SP) excitations have been investigated in the attenuated total reflection (ATR) Kretschmann configuration of prism/metal/organic ultrathin films. Structure and optical properties of organic ultrathin films have been evaluated using the ATR measurement due to SP excitations. Recently, emission light through the prism was observed using direct irradiation of a laser beam from air to the organic films, that is, reverse irradiation. The emission spectra strongly depended upon the emission angles through the prism and were caused by multiple SP excitations. The emission properties also depend upon structure of metal and organic thin films, dye molecules, separation between metal and molecules, molecular interaction, and so on. It is thought that the phenomenon is useful for application to new devices utilizing multiple SP excitations, and nanostructured devices of organic films using multiple SP excitations are described.

DOI： 10.1080/15421400390263820

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Self-assembled layer-by-layer films were fabricated on Ag-evaporated glass substrates using Direct Red 80 (DR80) azobenzene dye and poly (diallyldimethylammonium chloride) (PDADMAC), The properties of attenuated total reflection (ATR) and emission due to surface plasmon excitation were investigated. The ATR was measured for the Kretschmann configuration of a prism/Ag/layer-by-layer film structure and the emission through the prism was measured when the sample was excited by reverse irradiation in the Kretschmann configuration. The peak angles of the emission spectra almost agreed with the resonant angles of the ATR curves. The shapes of the emission spectra also corresponded to the ATR curves. ne structural change of the self-assembled films due to photoisomerization of DR80 molecules was also investigated. From the ATR measurements, the structure of the self-assembled films was found to change due to the photoisomerization by the irradiation of polarized visible light. The surface roughness of the self-assembled films due to the photoisomerization was examined from the scattered light measurements.

DOI： 10.1080/744819019

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Language：English   Publishing type：Research paper (international conference proceedings)  

Alternate ultrathin films of water-soluble copper (II) phthalocyanine-3, 4′,4″,4‴-tetrasulfonic acid (CuPcTs) and poly(diallyldimethylammonium chloride) (PDADMAC) were fabricated using the electrostatic layer-by-layer self-assembly technique. Linear depositions of the bilayers were observed from the UV-vis absorption spectra and ellipsometry. The average thickness of the CuPcTs monolayer obtained from ellipsometry was about 1.2nm and CuPcTb molecules were estimated to be tilted to the film surface. The cyclic votammo-gram (C-V) of the fabricated films in aqueous solution containing 0.1 M KCl suggested the oxidation and reduction of the CuPcTb at around +0.9 V and 0.05 V respectively. UV-vis absorption spectra were observed for the films at applied voltages of 0.8 Vand 0 V in the KCl aqueous solution and reversible absorption changes were observed.

DOI： 10.1080/15421400390264054

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Polystyrene sphere films were fabricated and the optical properties were investigated using surface plasmon spectroscopy (SPS) and emitted light due to reverse irradiation utilizing SPS Kretschmann configuration. The films were fabricated using sphere dispersed solution with various diameters from about 100 to 300 nm. The morphologies of the fabricated films were observed using atomic force microscopy and the sphere films had almost three layer structure. In SPS curve, large dip and shallow broad dip were observed at around 75degrees and 50degrees, respectively. The dips were considered to be due to the three layer structure and some defects in the film. Furthermore, emitted lights due to reverse irradiation were also observed as a function of the emitted angle in the Kretschmann configuration of the SPS measurement. Emitted lights due to surface plasmon excitation were also observed and the peak angle of the emitted light almost corresponded to the dip angle of the SPS curves.

DOI： 10.1080/15421400390263848

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Taylor and Francis Inc.  

Polystyrene sphere films were fabricated and the optical properties were investigated using surface plasmon spectroscopy (SPS) and emitted light due to reverse irradiation utilizing SPS Kretschmann configuration. The films were fabricated using sphere dispersed solution with various diameters from about 100 to 300 nm. The morphologies of the fabricated films were observed using atomic force microscopy and the sphere films had almost three layer structure. In SPS curve, large dip and shallow broad dip were observed at around 75° and 50°, respectively. The dips were considered to be due to the three layer structure and some defects in the film. Furthermore, emitted lights due to reverse irradiation were also observed as a function of the emitted angle in the Kretschmann configuration of the SPS measurement. Emitted lights due to surface plasmon excitation were also observed and the peak angle of the emitted light almost corresponded to the dip angle of the SPS curves.

DOI： 10.1080/744819015

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Emission light through the prism in the Kretschmann configuration of prism/Ag thin film/rhodamine-B (RB) Langmuir-Blodgett (LB) film has been observed by means of direct irradiation of a laser beam from air to the RB LB film, that is, the reverse irradiation method against the conventional attenuated total reflection (ATR) method. The emission light intensities and the spectra strongly depended upon the emission angle at the prism. The relation between the peak wavelengths of the spectra and the emission angles corresponded to the dispersion property of the resonant excitations of surface plasmons (SPs) in the ATR configuration. It was concluded that the emission light was caused by multiple excitations of SPs in the ATR configuration. Emission light through the prism was also observed below the reflection angle of the resonant one when the SP was resonantly excited in the conventional ATR measurement. This emission light also showed the same property as the one in the reverse irradiation method. It is thought that the phenomenon will be used as a new sensing device. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0928-4931(02)00199-6

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Short-circuit photocurrents (I-SC) due to surface plasmon (SP) excitations were investigated for the solar cells using Langmuir-Blodgett (LB) films of merocyanine (MC) dye molecules. The Schottky photoelectric devices with two kinds of structures, that is, prism/Al/MC LB film/Ag (type A) and prism/MgF2/AlMC LB film/Ag (type B) were prepared. Type A has the Kretschmann configuration and type B has both the Kretschmann and the Otto configurations. In the attenuated total reflection (ATR) measurements, SPs were resonantly excited at the interface between Ag and air for type A and at the interfaces between MgF2 and Al and between Ag and air for type B. The ATR and I-SC properties were simultaneously measured as a function of the incident angles of the laser beams. The peaks of I-SC corresponded to the resonant angles of the ATR curves. The electric fields and optical absorption in the cells were also estimated. The calculated absorption in the MC layers as a function of the incident angles corresponded to the I-SC curves. The optical absorption in the MC layers turns out to be correlated directly to the profiles of I-SC. It was estimated that I-SC could be enhanced by the excitations of SPs in the ATR configurations. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0928-4931(02)00174-1

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Preparations of alternate layer-by-layer self-assembled films of poly(diallyldimethyl ammonium chloride) (PDADMAC) and Direct Red 80 (DR80, azobenzene dye) and photo-induced surface relief gratings (SRGs) of the films have been investigated in situ using attenuated total reflection (ATR), that is, surface plasmon resonance spectroscopy (SPS) and quartz crystal microbalance (QCM) measurements. Gratings of the PDADMAC/DR80 films were fabricated by exposure to interference patterns of Ar+ laser light at 488 nm for 30 min. The formation of the gratings was observed using atomic force microscopy (AFM). The films were used for applications to liquid crystal (LC) display devices, and aligning properties of nematic liquid crystal molecules, 5CB, on the SRG in the films were also investigated in a hybrid LC cell configuration by monitoring birefringence properties of the LC cell in situ. It was estimated that the LC molecules in the cell did not align immediately after the photo-induced SRG was inscribed, but almost along the gratings after heat treatment at 40 degreesC for 1 min. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0928-4931(02)00214-X

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Organic light emitting diodes (OLEDs) containing nanostructured cathode buffer layers were fabricated, and their electrical and emitting properties were investigated. The OLEDs have an ITO anode/CuPc/TPD/Alq3/buffer layer/Al cathode structure with the buffer layers made from nanostructured alternating layers Alq3 and Al. The driving voltage and the efficiency of the devices were improved by insertion of the buffer layer. It was estimated that some modulations of the Schottky barrier at the, Alq3 and the Al cathode interface were induced due to the insertion of the buffer layer and it caused an enhancement of electron injection from the Al cathode.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Attenuated total reflection (ATR) properties were measured for porphyrin Langmuir-Blodgett (LB) films, and the structure and response to NO2 gas were investigated. The porphyrin molecule was 5,10,15,20-tetrakis(3,4-bis[2-ethylhexyloxyphenyl])-21H,23H-porphine (EHO). The EHO LB films were deposited onto Ag evaporated glass substrates by a vertical dipping method with an ultrafast deposition rate of 1000 mm/min. The response of optical absorbance to NO2 gas was very fast. The thickness and the complex dielectric constants of the EHO LB films evaluated from the ATR properties measured at 632.8 nm were thought to be related to the island structure of the EHO LB films. The isolated micron-size domains, which are themselves composed of grains of several nm in diameter, were also observed in the EHO LB films by atomic force microscopy. The ATR properties at 488.0 nm were considered to be related to the dispersion properties due to the optical absorption band of the EHO LB films. From the NO2 gas response measurements, the ATR properties at 488.0 nm were found to be more sensitive than those at 632.8 nm. The response to NO2 gas and the recovery properties in the ATR measurements were also examined.

DOI： 10.1143/JJAP.41.2779

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Photoinduced in-plane alignments of nematic liquid crystal (LC) molecules, 5CB, have been investigated in a LC cell prepared with alternate self-assembled films of polyelectrolytes and low-molecular-weight azobenzene molecules on gold electrodes using the attenuated total reflection (ATR) measurement method. A high dichroism of the self-assembled film was observed with the irradiation of linearly polarized light. The ATR properties due to excitations of surface plasmon polaritons (SPP) were observed in the LC cell and changed with the irradiation of linearly polarized visible light to the LC cell. The experimental results corresponded well with the calculated shifts at different orientation states of 5CB molecules. It was estimated that the LC molecules have in-plane alignments and that the LC molecules are oriented perpendicular to the polarization direction of the irradiated visible light. The molecular orientations could be controlled by the polarization direction of irradiated light on the hybrid LC cell. In-situ observations for the cell were also carried out during the irradiation. Furthermore, the thickness and dielectric constants of the self-assembled films were evaluated using the ATR method.

DOI： 10.1143/JJAP.41.2753

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Light emission from the prism has been investigated for the attenuated total reflection (ATR) Kretschmann configuration of prism/silver (Ag) film/organic dye thin films by means of the direct irradiation of a laser beam from air to the organic dye films, that is, reverse irradiation. Light emission was observed for merocyanine (MC) Langmuir-Blodgett (LB) films and hetero LB films of MC and crystal violet (CV) on Ag films using reverse irradiation, The light emission intensities and the spectra strongly depended upon the emission angles,v,here the light was observed through the prism. The relation between the peak wavelengths and the emission angles corresponded to the dispersion property of the resonant excitation of surface plasmons (SPs) in the ATR configuration. From the calculated dispersion properties of SPs, it was estimated that the light emission was caused by multiple excitations of SPs. The light emission property also depended upon the structure of the organic molecular thin films, and it was thought that the light emission from the hetero film of MC and CV was due to energy transfer from MC to CV molecules. It is thought that the phenomenon is useful for application to a new luminescent device and sensors.

DOI： 10.1143/JJAP.41.2774

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Language：English   Publisher：AMER CHEMICAL SOC  

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Language：English   Publisher：AMER CHEMICAL SOC  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Photoluminescent SrAl2O4:Eu,Dy thin films were successfully prepared by a pulsed ion-beam evaporation method without substrate heating or sample annealing. The crystallinity of the films was observed by X-ray diffraction and large-area high-resolution electron microscopy. From the above results and photoluminescence spectra (PL), it was concluded that the intensity at the peak in PL spectra is related to the volume fraction of a crystallized SrAl2O4,:Eu,Dy phase in the thin films. (C) 2002 Elsevier Science B.V All rights reserved.

DOI： 10.1016/S0040-6090(02)00027-5

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Elsevier  

The photo-induced in-plane alignment of nematic liquid crystal (LC) molecules, 5CB, has been investigated in a cell prepared with alternate layer-by-layer self-assembly of polyelectrolyte and low-molecular weight azobenzene dye films on gold electrodes using the attenuated total reflection (ATR) measurement method. The ATR properties due to excitation of surface plasmon polaritons were observed in the LC cell. They sensitively changed with irradiation of linearly polarized visible light. The experimental results corresponded well with the calculated ATR curves at different polarization states. We have demonstrated that in-plane alignment of the LC molecules on the self-assembled films could also be controlled by the polarization direction of irradiated visible light on the LC cell. © 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0927-7757(01)01020-2

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The UV-vis absorbance spectrum of LB film assemblies of 5,10,15,20-tetrakis(3,4-bis[2-ethylhexyloxyphenyl])21H,23H-porphine is very sensitive to low concentrations of NO2. LB films prepared at very high deposition rates (similar to 1000 mm min(-1)) yield t(50) response and recovery times of 25 and 33 s, respectively, and show a sensitivity of 60% relative absorbance change (at 430 nm) for 4.4 ppm NO2. Atomic force microscopy shows that the morphology of these films is characterised by isolated micron-size domains, which are themselves composed of grains of several nm in diameter. This unconventional LB structure leads to a useful sensing material as a result of the molecular functionality of the porphyrin coupled to the enhanced surface area of the porous film assembly. The optical response of the EHO gradually decreases as its temperature is increased, resulting from the shift in the adsorption-desorption equilibrium towards desorption. An activation energy for adsorption of 0.68 eV is obtained. The spectrum recovers fully after exposure to NO2 and the rate of recovery can be accelerated dramatically with gentle heating (similar to 350 K) for a few seconds. The concentration dependence of the optical response over the range 0.8-4.4 ppm follows a Langmuir model. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0927-7757(01)01011-1

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Photo-induced surface relief gratings of alternate layer-by-layer self-assembled films containing azobenzene dyes were fabricated. The alignment properties of nematic liquid crystal (LC) molecules on these films were investigated in a hybrid LC cell configuration. Poly(diallyldimethylammonium chloride) (PDADMAC) and Direct Red 80 (DR80, azobenzene dye) were deposited using the alternate layer-by-layer self-assembly method. The gratings of the PDADMAC/DR80 films were fabricated by exposure to interference patterns of Ar+ laser light at 488 rim. The formation of the gratings on the films was observed using atomic force microscopy. Furthermore, the alignment properties of LC molecules, 5CB, on the films were investigated by monitoring the change in birefringence of the LC cell in situ, This in-plane alignment was observed after similar to 30 min exposure with the laser, simultaneous with the formation of the interference patterns. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0927-7757(01)01005-6

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Electroluminescent (EL) devices of metal-free phthalocyanines (H2Pc) were fabricated and electrical and luminescent properties due to NO, gas adsorption were studied. The device had an ITO bottom electrode (anode)/H(2)pC (100 nm)/Al top electrode (cathode) structure. The H2Pc and the Al films were vacuum evaporated. Especially, the Al films were deposited using an oblique deposition method in order to form porous structure to enable NO2 gas adsorption into the H2PC layer through the Al film. The conduction currents and the EL intensities of the device increased with NO2 adsorption. Open-circuit voltage generations due to NO2 gas adsorption were also observed. It was estimated that the adsorbed NO2 molecules in H2Pc generated holes by capturing negative electrons and charge separation of the negative charged NO2 and positive holes induced the open circuit voltage. It was concluded that the increase in the conduction currents due to the gas adsorption was caused by the modification of the depletion layer, and that efficient injection of electrons and recombination of carriers produced the improvement in the EL efficiency. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0927-7757(01)01018-4

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DOI： 10.1016/S0927-7757(01)01020-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Surface plasmon resonance (SPR) properties were measured for porphyrin Langmuir-Blodgett (LB) films and the response to NO2 gas was investigated. The porphyrin molecule was 5,10,15,20-tetrakis(3,4-bis[2-ethylhexy-loxyphenyl])-21H, 23H-porphine (EHO). The EHO porphyrin LB films were deposited onto the cover glass with evaporated Ag thin films by vertical dipping method with a very fast deposition rate of 1000 mm min(-1). The SPR measurements were carried out at wavelengths of 488 and 632.8 nm. The SPR properties measured at 488 nm were considered to be related to the dispersion properties due to the optical absorption band of the EHO LB films. The thickness and the complex dielectric constants of the EHO LB films evaluated from the SPR properties measured at 632.8 nm were thought to be related to the island structure of the EHO LB films. From the NO2 gas response measurements, the SPR properties at 488 nm were found to be more sensitive to NO2 gas than those at 632.8 nm. The response rate to NO2 gas and the recovery properties were also examined. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0927-7757(01)01006-8

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Surface breakdown phenomenon of printed wiring board was investigated with increasing temperature from 23°C to 150°C. The experiment was carried out by do pulse voltage with the frequencies in the range of 50Hz to 150Hz. Printed wiring boards of epoxy resin laminate have been employed to investigate the effects of the surface temperature, electrode distance and the frequencies of applied voltage on the discharge quantity. The study revealed that the time to breakdown decreases with increasing the temperature, increasing the frequency of applied voltage and decreasing the electrode distance. The characteristics of discharge currents with increased temperature and the electrode distance were discussed by power spectral density of discharge current. The results show that the power spectral density of discharge currents increases with increasing the temperature, and decreasing the electrode distance. © 2002, The Japan Institute of Electronics Packaging. All rights reserved.

DOI： 10.5104/jiep.5.401

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Surface plasmon (SP) excitations have been investigated in the attenuated total reflection (ATR) Kretschmann configuration of prism/metal/Langmuir-Blodgett (LB) films containing dyes. The emission light through the prism was observed using direct irradiation of a laser beam from air to the LB films, i.e., reverse irradiation. The emission intensities depend on the emission angles through the prism, nanostructure of metal and LB films, dye molecules, separation between metal and dye molecules, interactions of dye molecules, etc. The spectra is strongly depended on the emission angles, and the emission light was caused by multiple SP excitations. Nanostructured devices of LB films using SP excitations are described.

DOI： 10.1142/S0219581X02000413

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Surface breakdown phenomenon of printed wiring board was investigated under decreased pressure from 100kPa to lkPa. The experiment was carried out by do pulse voltage with the frequencies in the range of 50Hz to 200Hz. Printed wiring boards of epoxy resin laminate have been employed to investigate the effects of atmospheric pressure and the frequencies of applied voltage on the discharge quantity. The study revealed that the time to breakdown increases with lowering pressure, and it decreases with increasing the frequency of applied voltage. The characteristics of discharge currents under decreased pressures and the frequency were discussed by using power spectral density of discharge current. The results show that the power spectral density of discharge currents decreases at 100Hz, but increases at 200Hz as the atmospheric pressure decreases. © 2002, The Japan Institute of Electronics Packaging. All rights reserved.

DOI： 10.5104/jiep.5.604

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Emission light through the prism has been investigated from the Kretschmann configuration of the prism/ Ag thin film/ rhodamine-B (RB) LB Film in the resonant excitation of the attenuated total reflection (ATR) measurement. The emission light and the spectra strongly depended upon the emission angles where the light was observed. The emission properties corresponded to the dispersion property of the resonant excitations of surface plasmons (SPs) in the ATR configuration. It was concluded that the emission light was caused by multiple excitations of SPs in the AFR configuration. It is thought that the phenomenon will be used as a new sensing device.

DOI： 10.1080/10587250290088528

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MATERIALS RESEARCH SOCIETY  

Organic light emitting diodes (OLEDs) containing cathode buffer layers of nanometer thickness were fabricated and their electrical and emitting properties were investigated. The OLEDs have an indium tin oxide (ITO) anode/ copper phthalocyanine (CuPc) / N, N'-dephenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine (TPD) / 8- hydroxyquinoline aluminum (Alq3) / buffer layer / Al cathode structure with the buffer layers made from alternating thin films of Alq3 and Al with nanometer thickness. Improvement of driving voltage and the efficiency for the devices were observed by insertion of the buffer layer. It was estimated that some modulations of the Schottky barrier at the Alq3 and the Al cathode interface were induced due to the insertion of the buffer layer and it caused an enhancement of electron injection from the Al cathode. A model of the band structure at the buffer layer was proposed.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MATERIALS RESEARCH SOCIETY  

Short-circuit photocurrents (I-SC) due to surface plasmon (SP) excitations have been investigated for the photoelectric cells using Langmuir-Blodgett (LB) films of merocyanine (MC) dye. The MC dye exhibits p-type conduction, and the Schottky and Ohmic contacts are obtained at the interfaces between MC LB films and Al thin films and between MC LB films and Ag thin films, respectively. Since the Schottky diodes show the photoelectric effects, the Schottky photoelectric cells have been constructed. The cells with two kinds of structures, that is, prism/Al/MC/Ag (type I) and prism/MgF2/Al/MC/Ag (type II), have been prepared. In the attenuated total reflection (ATR) method, the types I and II have the Kretschmann and both the Kretschmann and Otto configurations, respectively. SP has been resonantly excited at the interface between Ag and air for the type I and at the interfaces between MgF2 and Al between Ag and air for the type II. The ATR and the Isc properties have been simultaneously measured as a function of the incident angles of the laser beams. The peaks of the I-SC have corresponded to the resonant angles of the ATR curves. The electric fields and optical absorptions in the cells have been also calculated using the dielectric constants and the film thicknesses obtained from the ATR measurements. The calculated absorptions in the MC layers as a function of the incident angles have corresponded to the results of I-SC. It has been estimated that the I-SC for both types I and II could be enhanced by the excitations of SP in the ATR configurations.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The discipline of molecular electronics has grown rapidly over the last 10 years and is driven by the promise of the enhanced applied physical properties of functionalised organic materials compared to their inorganic partners. The subject can be divided generally into two broad themes, namely active molecular-scale electronics (or photonics), in which the control or generation of charge (or photons) at the nanoscale is attempted, and passive supra-molecular electronics (or photonics), in which the specific functionality of the molecules is modified by some interaction or process. In this paper, an example of the latter approach to molecular electronics will be given and this will describe the gas sensing properties of a tetra-substituted porphyrin molecule. The optical absorbance spectrum of LB film assemblies of 5,10,15,20-tetrakis(3,4-bis[2-ethylhexyloxy]phenyl)-21H,23H-porphine(EHO) is highly sensitive to low concentrations of NO2. LB films prepared at much faster than conventional deposition rates (similar to 1000 min min(-1)) yield t(50) response and recovery times of 25 and 33 s, respectively, and show a sensitivity of 60% relative absorbance change (at 430 nm) for 4.4 ppm NO2. The morphology of these films is revealed using atomic force microscopy to contain isolated micron-size domains which are composed of grains of several nm in diameter. This unconventional structure leads to a useful sensing material as a result of the molecular functionality of the porphyrin coupled to the enhanced surface area of the porous film assembly. The EHO film shows a gradually diminishing optical response as its temperature is increased, resulting from the shift in the adsorption- desorption equilibrium towards desorption. The spectrum recovers fully after exposure to NO2. The rate of recovery is slow at room temperature but can be accelerated dramatically with gentle heating (similar to 350 K) for a few seconds. The kinetics of the gas sensing process have been modelled and found to fit Elovichian surface adsorption for an initial fast surface adsorption process. This is followed by a much slower diffusive process in which the NO2 molecules diffuse through the bulk of the assembly. The concentration dependence of the optical response over the range 0.8-4.4 ppm follows a Langmuir model. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0040-6090(01)01080-X

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Attenuated total reflection (ATR) properties, scattered light and emission due to surface plasmon (SP) excitation from merocyanine (MC) Langmuir-Blodgett (LB) films on Ag thin films were investigated. A Kretschmann configuration of the ATR measurement, prism/Ag thin film/air or prism/Ag thin film/MC LB film/air structure, were used for the SP excitation. The thicknesses and the dielectric constants of the Ag thin films and the MC LB films were obtained from the ATR measurement. Scattered light due to the SP excitation was also observed from the Ag thin film or the MC LB film in the ATR measurements. Furthermore, emission was observed through the prism when a laser beam was irradiated to the sample from the air. The angles of the emission peaks almost corresponded to the resonant angles of the ATR curves. It was considered that the emission was due to the SP excitation and depended on the surface roughness of the films. The intensity of the emission from the Ag thin film strongly depended on the incident angle of the laser beam. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0040-6090(01)01106-3

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1541/ieejfms1990.121.7_683

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1541/ieejfms1990.121.7_642

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DOI： 10.1541/ieejfms1990.121.7_677

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

SrAl2O4 activated with Eu, a long-phosphorescence material with high brightness, has been successfully deposited on Si substrates using intense pulsed ion-beam evaporation. Efficient preparation of long-phosphorescence thin films has been achieved using a high-density ablation plasma produced by the interaction of an intense pulsed ion-beam with the SrAl2O4:Eu target. The prepared SrAl2O4:Eu thin films had a polycrystalline structure without annealing and showed a typical photoluminescence of SrAl2O4:Eu at around 520 nm. Thermoluminescence (TL) measurements were carried out in order to obtain the lifetimes of the phosphorescence. In particular, TL spectra in the higher temperature region, which contributed to the long phosphorescence, were examined by the partial heating technique to evaluate the distributed trap depths and the lifetimes. The phosphorescence lifetime at 300 K for the prepared film was found to be about 180 min.

DOI： 10.1143/JJAP.40.1038

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

SrAl2O4 activated with Eu phosphors has been known to exhibit high brightness and long-lasting phosphorescence without radioactive materials. In this paper, SrAl2O4Eu thin films have been successfully deposited on Si(100) or graphite substrates using an intense pulsed ion-beam evaporation technique. The results of X-ray diffraction and photoluminescence suggest that SrAl2O4:Eu thin films which have a polycrystalline structure can be produced in vacuum, without substrate heating and annealing. The composition and morphology of the films have been analyzed by Rutherford backscattering spectroscopy (RBS) and scanning electron microscopy (SEM). From RES analysis, we have obtained good stoichiometry between the target and the films prepared.

DOI： 10.1143/JJAP.40.1035

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DOI： 10.1016/S1383-7303(01)80017-X

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DOI： 10.1016/S1383-7303(01)80018-1

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DOI： 10.1016/S1383-7303(01)80015-6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Spectra of emission light from Ag/ Rhodamine-B (RB) LB films due to surface plasmon (SP) excitations have been investigated using an attenuated total reflection (ATR) method and a reversed ATR (R-ATR) method. In the R-ATR configuration, emission light was observed through the prism, and the intensities and spectra strongly depended upon the emission angle where the light was observed. The relation between the wavelengths and the emission angles agreed with the resonant conditions of excitations of SPs in the ATR configuration. It was concluded that the emission light was caused by excitations of multiple SPs.

DOI： 10.1080/10587250108030085

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The optical absorbance spectrum of LB film assemblies of 5,10,15,20-tetrakis[3,4-bis(2-ethylhexyloxy)phenyl]-21H,23H-porphine (EHO) is highly sensitive to low concentrations of NO2 in nitrogen. LB films prepared at much faster than conventional deposition rates (similar to 1000 mm min(-1)) yield t(50) response and recovery times of 25 s and 33 s respectively and show a sensitivity of 60% relative absorbance change (at 430 nm) for 4.4 ppm NO2. The morphology of these films is revealed using atomic force microscopy to contain isolated micron-size domains which are themselves composed of grains of several nm in diameter. This unconventional structure leads to a useful sensing material as a result of the molecular functionality of the porphyrin coupled to the enhanced surface area of the porous film assembly. The EHO film shows a gradually diminishing optical response as its temperature is increased, resulting from the shift in the adsorption-desorption equilibrium towards desorption as expected. The UV-visible spectrum recovers fully after exposure to NO2. The rate of recovery is slow at room temperature but can be accelerated dramatically with gentle heating (similar to 350 K) for a few seconds. The concentration dependence of the optical response over the range 0.8-4.4 ppm follows a Langmuir model.

DOI： 10.1039/B006342H

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

A liquid crystal (LC) cell with alternate self-assembled films containing azobenzene dye as aligning layers was fabricated and photo-induced inplane alignments of nematic LC molecules, 5CB, have been investigated in the cell using the attenuated total reflection (ATR) method. The ATR properties due to excitations of surface plasmon polaritons (SPP) were observed in the LC cell and sensitively changed with irradiation of linearly polarized visible light to the LC cell. The experimental results corresponded well with the calculated shifts at different alignment states. It was evaluated that the LC molecules within the penetration length of the SPP (about 130 nm) were aligned perpendicular to the polarized direction of the irradiation light, and that the tilt angle was almost 0 degree.

DOI： 10.1080/10587250108030069

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Taylor and Francis Inc.  

Spectra of emission light from Ag/ Rhodamine-B (RB) LB films due to surface plasmon (SP) excitations have been investigated using an attenuated total reflection (ATR) method and a reversed ATR (RATR) method. In the R-ATR configuration, emission light was observed through the prism, and the intensities and spectra strongly depended upon the emission angle where the light was observed. The relation between the wavelengths and the emission angles agreed with the resonant conditions of excitations of SPs in the ATR configuration. It was concluded that the emission light was caused by excitations of multiple SPs. © 2001 Taylor and Francis, Inc.

DOI： 10.1080/10587250108030085

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Short-circuit photocurrents (Isc) utilizing surface plasmon polariton (SPP) excitation were investigated for the merocyanine (MC) LB film photoelectric device. The device has: a prism/MgF2/Al/MC LB film/Ag structure. In the attenuated total reflection (ATR) configuration, SPPs were resonantly excited at the interfaces between MgF2 and Al (MgF2/Al) and between Ag and air (Ag/air). The thickness and the dielectric constants of the layers were evaluated from the ATR, measurements. Short-circuit photocurrent, I(SC)s, as a function of the incident angle of the laser beam were observed simultaneously during the ATR measurements. In the Ise curves, large and small peaks were observed, and the peak angles of the Ise almost corresponded to the dip angles of the ATR curves due to the SPF excitations. Electric fields and optical absorptions in the cell were calculated using the dielectric constants and the film thickness obtained from the ATR, measurements. The calculated absorption in the MC layer as a function of the incident angle corresponded to the Ise curve. Ii was thought that the optical absorption in the MC layer affected directly to the profile of the I-SC. Furthermore, the calculated absorption in the cell with the prism and the MgF2 layer exhibited much larger than that of the cell without them. It was estimated that the photocurrents were enhanced by the excitation of SPPs in the ATR configuration.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Langmuir-Blodgett (LB) films of crystal violet (CV) dyes incorporating cyanine (Cy) dyes (CVCy LB films) have been prepared by the diffusion-adsorption LB method, and the optical properties have been investigated. In the photoluminescence (PL) spectrum of the CVCy LB films, a weak, narrow peak at around 470 nm and an intense peak at around 700 nm were observed, which were caused by the Cy and the CV dyes, respectively. The PL peak at about 470 nm became more intense as the irradiation time of the laser excitation light increased. The PL peak initially appearing at about 700 nm, broadened and moved to lower wavelength with increasing irradiation time. CV/DSACy LB heterofilm of the CV LB film without Cy dyes on distearyldimethylammonium bromide (DSA) LB film with adsorbed Cy dyes (DSACy LB film) was also prepared for the comparison. The absorption spectrum was similar to that of the CVCy LB film. On the contrary, in the PL spectrum of the CV/DSACy LB hetrofilm, the peak at around 470 nm was more intense and the peak at around 700 nm was weaker. From the results, the PL properties of the CVCy LB films were thought to be related to the energy transfer between the CV and the Cy dyes. (C) 2000 Elsevier Science S.A. All rights reserved.

DOI： 10.1016/S0379-6779(99)00391-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GORDON BREACH SCI PUBL LTD  

Photo-induced in-plane alignments of nematic liquid crystal (LC) molecules, 5CB, have been investigated in the cell with alternate self-assembly films of polyelectrolyte and low-molecular weight dyes on the gold electrodes using the attenuated total reflection (ATR) measurement method. Reflectivities due to the excitations of the surface plasmon polariton (SPP) were observed in the ATR properties of the LC cell. In-plane switching of LC molecules adjacent to the aligning layer was evaluated from the ATR curves by means of irradiation of the linearly polarized visible light to the LC cell. It was also estimated that the re-orientation of the LC molecules occurred within about 130 nm from the surface of the aligning layer on the prism by the irradiation of the polarized light.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GORDON BREACH SCI PUBL LTD  

Surface plasmons (SPs) were resonantly excited for aluminum (Al) thin films and arachidate acid (C20) LB ultrathin films on the substrates in a Kretschmann configuration of the attenuated total reflection (ATR) method. Evanescent fields generating on the Al thin films and the LB films due to excitations of the SPs were detected as luminescent light from a metallic needle probe covered with CdS in the localized evanescent fields. The luminescent light, that is, the evanescent fields were measured as a Function of the incident angle of the laser beam exciting the SPs and as a function of the distance from the surface. The luminescent light intensity was biggest at a lower angle than the resonant angle. These properties were calculated and discussed. Evanescent fields were also measured for C20 LB films on Al thin films.

DOI： 10.1080/10587250008024908

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Taylor and Francis Inc.  

Photo-induced in-plane alignments of nematic liquid crystal (LC) molecules, 5CB, have been investigated in the cell with alternate self-assembly films of polyelectrolyte and low-molecular weight dyes on the gold electrodes using the attenuated total reflection (ATR) measurement method. Reflectivities due to the excitations of the surface plasmon polariton (SPP) were observed in the ATR properties of the LC cell. In-plane switching of LC molecules adjacent to the aligning layer was evaluated from the ATR curves by means of irradiation of the linearly polarized visible light to the LC cell. It was also estimated that the re-orientation of the LC molecules occurred within about 130 nm from the surface of the aligning layer on the prism by the irradiation of the polarized light. 2000 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.

DOI： 10.1080/10587250008024825

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GORDON BREACH SCI PUBL LTD  

In this study, photocurrents enhanced by the surface plasmon polariton (SPP) excitation were observed in a merocyanine (MC) Langmuir-Blodgett (LB) film cell. The excitation of the SPP was carried out by the incidence of a laser beam in the attenuated total reflection (ATR) measurement system. The excitation of the SPF induces the strong absorption of the incident light and large photocurrents in the device.

DOI： 10.1080/10587250008024907

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Tilt angles of nematic liquid crystal molecules, 5CB, have been investigated in the thick cells having aligning layers of polyimide (PI) Langmuir-Blodgett (LB) films on aluminum electrodes using the attenuated total reflection (ATR) measurement method. The ATR curves strongly depended upon AC voltages applied to the cells and the properties at each voltage were similar between 17 and 25 degrees C. The resonant excitations of the surface plasmon polariton (SPP) were observed in a broad region of the incident angle in the ATR measurements. The tilt angles of the liquid crystal molecules were calculated by fitting the theoretical ATR curves to the experimental ones. The results showed that the ATR measurement method was very useful for evaluating behaviors of liquid crystal molecules in thick cells. (C) 1999 Elsevier Science S.A. All rights reserved.

DOI： 10.1016/S0928-4931(99)00037-5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

A new experimental system has been constructed to detect evanescent fields of metal surface plasmons (SPs) using a metallic probe tip covered with fluorescence cadmium sulfide (CdS). The evanescent fields of the SPs sensitive to the metal interfaces were observed as fluorescent light from CdS on the tip. No additional lock-in detection technique with a vibrating probe tip is necessary in the system, in spite of the scattered light enhanced by SP due to the surface roughness. The fluorescent light measured for the Al film sample shows exponential decay with distance from the sample surface, indicating that the SP evanescent fields are detected with our apparatus. (C) 1999 American Institute of Physics. [S0034-6748(99)04310-5].

DOI： 10.1063/1.1150020

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

SrAl2O4 activated with Eu, one of the long phosphorescent materials with high brightness, was deposited on Si substrates using an RF sputtering technique with facing targets. The as-deposited SrAl2O4:Eu films did not show any peaks in the X-ray diffraction spectra, and the photoluminescence (PL) was not observed. However, the X-ray diffraction peaks were observed after annealing, and a PL peak at about 520 nm was observed after annealing in a reducing H-2 + Ar gas or an inert Ar gas. The composition and morphology of the sputtered films were observed using an energy dispersive spectrometer (EDS) and a scanning electron microscope (SEM). The thermoluminescence (TL) measurements were carried out, and decay times of the phosphorescence and the activation energies were obtained from the peak temperature. TL spectra in higher temperature region which contribute for the long phosphorescence, were examined by the partial heating technique to evaluate the distributed trap depths and the lifetimes. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-2313(99)00036-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

In the paper we report the experimental results for ac losses in HTS coil carrying ac transport current. The tests of ac losses mere performed by the electrical method at 77 K and 4.2 K. The HTS tape consists of 55 multi-filamentary silver-sheathed BSCCO 2223 tape without twisting. The sample coil was made by the React and Wind method using insulated tape conductor. The coil has the inner diameter of 46 mm, outer diameter of 87 mm, height of 14.5 mm, and the number of turns is 300 turns. The measured ac losses were compared with the conventional theory based on the critical state model. In the region of low transport current, the theoretical results agreed well the experimental results. We also investigated the distribution of the sc losses in the coil to study the effects of magnetic field distribution on ac losses.

DOI： 10.1109/77.783425

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Magnetics Society of Japan  

We attempted to deposit a hexagonal barium ferrite (BaM) film with a thickness of less than 50 nm by using an alternate periodic atomic layer deposition method. BaM films from 11.5 to 115 nm thick were deposited at 630°C on a ZnFe₂O₄ (20nm) underlayer of (111) texture. Compared with films deposited by conventional sputtering, the film obtained in this study had excellent c-axis orientation and crystallinity. Even the BaM film with a thickness of 11.5 nm had clear X-ray diffraction peaks from the BaM c-plane. The crystallite size of the film decreased significantly as the thickness of the BaM layer decreased, and the typical crystallite size of the 11.5-nm-thick film was about 25 nm. The coercive force of the film in the perpendicular direction, however, decreased markedly as the thickness of the BaM layer decreased below 23 nm. A magnetic intermediate layer was produced in the film between the BaM layer and ZnFe₂O₄ underlayer, and thus the film had a double layer structure composed of a BaM layer with perpendicular magnetization and an intermediate layer with an in-plane magnetization.

DOI： 10.3379/jmsjmag.23.1209

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DOI： 10.1541/ieejfms1990.119.1_124

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GORDON BREACH SCI PUBL LTD  

Attenuated total reflection (ATR) properties have been investigated for azobenzene LB films adsorbing cyanine dyes on aluminum thin films. The ATR properties changed as the LB films were annealed. From the ATR properties, the complex dielectric constants were calculated as a uniaxial anisotropic dielectrics. It was thought that the ATR properties and the dielectric constants were caused by the dispersion properties due to the absorption bands.

DOI： 10.1080/10587259908026790

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GORDON BREACH SCI PUBL LTD  

Scattered light properties from Ag thin films and arachidic acid (C20) Langmuir-Blodgett (LB) films on the Ag thin films were investigated to evaluate the surface roughnesses of these films utilizing the surface plasmon polariton (SPP) excited in the attenuated total reflection (ATR) configuration. The surface roughness of the films was estimated from the angular distribution of the scattered lights. This result was qualitatively corresponding to the evaluation by the atomic force microscope (AFM) measurements.

DOI： 10.1080/10587259908026796

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1541/ieejfms1990.118.12_1405

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Arachidic acid (C20) Langmuir-Blodgett (LB) films with cyanine (Cy) dyes were fabricated by the diffusion-adsorption LB method with applying bias voltages V-d, and the structures and the electrical properties were investigated. From the absorption spectra, the amount and the orientation of the Cy dyes and the formation of the aggregates in the LB films were found to be controlled by V-d. The electrical properties were investigated from conduction current and thermally stimulated current (TSC) measurements. The current-voltage characteristics and: transient current properties showed the ionic hopping conduction. From the transient current properties. the sample deposited under negative V-d seemed to include larger amounts: of mobile ions and the mobile ions were supposed to be positive. The TSCs were also due to the ionic space charge polarization. The results in this work will be useful for the control of electrical properties in LB film devices. (C) 1998 Elsevier Science S,A. All rights reserved.

DOI： 10.1016/S0040-6090(98)00942-0

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DOI： 10.1541/ieejfms1990.118.9_1015

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Ultrathin films were formed from two types of non-conjugated polyelectrolytes, that is, polyallylamine (PAH) and polystyrensulfonate (PSS) using a self-assembly process and their electrical properties were investigated. Current versus voltage properties of the devices showed hopping conduction. The conduction was considered to be due to the migration of mobile ions in the sample, and that was also supported by temperature and humidity dependence of transient currents. Furthermore, thermally stimulated currents (TSCs) properties also suggested the ionic space charge polarization. Although the origin of mobile ions is not yet clear, the existence of sodium in the films was observed from the electron spectroscopy for the chemical analysis (ESCA). The humidity (i.e. water in the devices) also had a great influence on the electrical properties. The sodium ions and/or oxonium ions in the device are considered mobile ions. (C) 1998 Elsevier Science S.A. All rights reserved.

DOI： 10.1016/S0040-6090(98)00630-0

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