Kazuhiro Saito

Toshiba (Japan)

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Michio Sugi

Toin University of Yokohama

Keiichi Ikegami

Dokkyo Medical University Saitama Medical Center

Mitsuyoshi Saito

Washington University in St. Louis

Shin‐ichi Kuroda

Nagoya University

Tetsuya Taima

Kanazawa University

Yuka Tabe

Waseda University

Shin-ichi Kuroda

Nagoya University

Kazunari FUJIYAMA

Meijo University

Takayoshi Nakamura

Hokkaido University

Kiyoshi Yase

National Institute of Advanced Industrial Science and Technology

Cooperative Institutions

The University of Tokyo

National Institute of Advanced Industrial Science and Technology

Toshiba (Japan)

Tohoku University

Tokyo Institute of Technology

Tokyo University of Science

University of Tsukuba

Osaka University

Kyoto University

Japan Science and Technology Agency

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Flow-orientation effect in batch-produced Langmuir–Blodgett films: Observation of the unsteady flow around the stagnation point

Journal of Applied Physics (1991)

Yuka Tabe Keiichi Ikegami Shin-ichi Kuroda Kazuhiro Saito Mitsuyoshi Saito

The in-plane anisotropy of the Langmuir–Blodgett films of a merocyanine-fatty acid mixed system has been further studied for two different cases of batch production with the substrates aligned face to face and side by side, respectively, to clarify the limitations of the flow-orientation model based on the ideal-fluid approximation. For the side-by-side case, satisfactory coincidence is found between the model and experiment. The actual dichroic behavior deviates from that predicted for the face-to-face case with smaller intersubstrate distances. It was speculated that the stagnation point is associated with anomaly in velocity which is responsible for this discrepancy. In order to examine this, the flow of the monolayer on the water surface during the deposition has been observed using sulphur powder as marker in addition to the optical measurements. The actual flow deviates from that expected from the model and is associated with unsteady motion around the stagnation point as previously speculated. It is indicated that the ideal-fluid approximation is inappropriate for the face-to-face case with smaller distances, leading to the prediction inconsistent with the actual dichroic behavior.

Vicinal

Dichroic glass

10.1063/1.349553

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Citations (6)

Optical activity of incommensurate state of [N(CH3)4]2CuCl4

Journal of Applied Physics (1990)

Kazuhiro Saito Hideaki Sugiya J. Kobayashi

By applying the HAUP (high-accuracy universal polarimeter) method, [N(CH3)4]2CuCl4 was found to be optically active in its incommensurate phase, e.g., g23=3.9×10−5 at 24 °C. The temperature dependence of g23 was obtained. By making use of the fact that the commensurate phase of [N(CH3)4]2CuCl4 is ferroelastic and centrosymmetric, the temperature dependence of the soliton density in its incommensurate phase was deduced by this optical measurement. It is suggested that the HAUP method will become a new and direct method for measuring soliton densities of incommensurate states.

Polarimeter

10.1063/1.346806

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Citations (37)

Mg-doped C60 thin film as improved n-type organic semiconductor for a solar cell

Applied Physics Letters (2003)

Masayuki Chikamatsu Tetsuya Taima Yūji Yoshida Kazuhiro Saito Kiyoshi Yase

Mg doping effect on a [2-methoxy, 5-(2′-ethylhexyloxy)-1,4-phenylene-vinylene] (MEH-PPV)/C60 bilayer solar cell has been investigated. We find that the Mg doping occurs during the deposition of the Mg top electrode onto the C60 film and that the solar cell property is markedly improved by the doping. The power conversion efficiency of the Mg-doped device under 100 mW/cm2 white light illumination is 0.54%, which is approximately 400 times larger than that of the nondoped device.

Organic semiconductor

Wide-bandgap semiconductor

10.1063/1.1637943

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Low-refractive-index dye-aggregate films with small absorption based on anomalous dispersion

Applied Optics (2005)

Takashi Wakamatsu Keita Watanabe Kazuhiro Saito

Complex-refractive-index spectra of Squarylium (SQ) dye-aggregate films deposited upon metal films have been investigated by measurements of properties of the films including absorption spectra (AS) and attenuated total reflection. Complex refractive indices are estimated by Kramers-Kronig analysis for the AS and by a theoretical curve-fitting analysis for attenuated total reflection. The dye-aggregate films exhibited an absorption that was blueshifted from that of a monomer, as a result of the H-aggregate formation of SQ molecules, and had a changing refractive index with anomalous dispersion about the H-absorption band. From both measurements of the SQ films it was found that there is a region of low absorption in the short-wavelength side of the absorption band and that the refractive index there is lower than that of glass.

Kramers–Kronig relations

Absorption band

Reflection

10.1364/ao.44.000906

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Citations (16)

Electroabsorption Spectra of Merocyanine J-Aggregate Langmuir-Blodgett Films

Japanese Journal of Applied Physics (1999)

Kazuhiro Saito

Electroabsorption spectra were measured for Langmuir-Blodgett (LB) films which contain a merocyanine J -aggregate monolayer. The LB films, which possess asymmetrical molecular arrangement, were employed to investigate linear electrochromism. A clear difference was observed in the spectra between linear and quadratic electrochromism.

Merocyanine

J-aggregate

10.1143/jjap.38.2804

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Citations (3)

Technical Report of ISSP Ser. A: Number 2776

Takeshi Hanawa Kotaro Shinkawa Masayasu Ishikawa Kazuo Miyatani Kazuhiro Saito

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H-Aggregate Formation in Squarylium Langmuir−Blodgett Films

The Journal of Physical Chemistry B (2001)

Kazuhiro Saito

Langmuir−Blodgett (LB) films of a surfactant squarylium were prepared to investigate formation of H aggregates, which are characterized by blue-shifted sharp absorption bands. The LB films showed an aging effect in room temperature, and annealing was effective to promote H-aggregate formation. Photovoltaic cells of an Al/LB film/Ag structure were also fabricated to investigate the effect of H-aggregate formation for photoelectric conversion. Unlike the case in J-aggregate LB films, action spectra of the photocurrent in the cells were similar to the absorption spectra of the H-aggregate LB films, that is, the H bands can effectively contribute to the photocurrent. The aggregate formation seems to influence the nonradiative decay of excited dyes on metals by coupling with surface plasmon polaritons, which affects the efficiency of photoelectric conversion.

Photocurrent

J-aggregate

Photoelectric effect

10.1021/jp003141w

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Citations (40)

Nanocrystalline metal electrodes for high-efficiency organic solar cells

Applied Physics Letters (2004)

Tetsuya Taima Masayuki Chikamatsu Yūji Yoshida Kazuhiro Saito Kiyoshi Yase

We demonstrate that indium (In) nanocrystals can be used as efficient small-work function electrodes for organic solar cells. A Schottky-barrier solar cell consisting of the In nanoelectrodes, a zinc phthalocyanine (ZnPc) film as a p-type organic semiconductor, and a gold counterelectrode were assembled by vacuum evaporation on an indium-tin-oxide substrate. Nanoscopic Schottky barriers, which are the origins of photovoltaic effects, were formed at the In nanocrystal∕ZnPc molecule interfaces in the cell. Current density under a dark condition was markedly increased by the introduction of the nanoelectrodes. The power conversion efficiency under air mass 1.5 global solar conditions was 200 fold larger than those of the conventional Pc Schottky-barrier solar cells with film electrodes.

Indium tin oxide

Nanocrystalline material

Organic semiconductor

Vacuum evaporation

10.1063/1.1784879

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Citations (11)

D09 Fabrication of peeling tool by zinc electroplating : improving surface roughness and decentering

Seisan Kakou, Kousaku Kikai Bumon Kouenkai kouen rombunshuu/Seisan Kako, Kosaku Kikai Bumon Koenkai (2012)

Kazuhiro Saito Tadashi Akatsuka Amirul Mohammad Rie Tanabe Yoshiro Ito

In fabricating a micro tool used for micro EDM efficiently, a "peeling tool", which is a thin wire electrode (core) coated with a low-melting-point material (cladding), has been proposed. To improve an accuracy of the tool, however, it is necessary to reduce the decentering and the surface roughness of the tool. In this paper, effects of commonly used additive agents, polyethylene glycol (PEG) as a surfactant, and boric acid as a buffer to suppress the change in pH value, in electroplating of zinc cladding were investigated. Change in pH values of solutions was suppressed by both additives. The surface roughness of the cladding is improved by adding PEG It was found, however, that adding PEG made removal of the cladding by a discharge difficult.

Cladding (metalworking)

Boric acid

10.1299/jsmemmt.2012.9.207

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Observation of Langmuir-Blodgett Films by Scanning Tunneling Microscopy : Surfaces, Interfaces and Films

Japanese journal of applied physics. Pt. 1, Regular papers & short notes (1988)

Wataru Mizutani Masatsugu Shigeno Kazuhiro Saito Kazutoshi Watanabe Michio Sugi

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