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789 results on '"Fujii, Akihiko"'

106. Photoinduced anisotropic response of azobenzene chromophore functionalized multiwalled carbon nanotubes.

Author

Feng, Yiyu, Feng, Wei, Noda, Hideki, Fujii, Akihiko, Ozaki, Masanori, and Yoshino, Katsumi

Subjects
ANISOTROPY, NANOTUBES, PHOTOLUMINESCENCE, SPECTRUM analysis, ABSORPTION, THIN films
Abstract

Azobenzene chromophore covalently functionalized multiwalled carbon nanotubes (AZO-MWCNT) were synthesized and their optical properties were investigated by ultraviolet-visible absorption and photoluminescence spectroscopy. The polarized absorption of the AZO-MWCNT film was measured by cross-polarized light along the directions parallel and perpendicular to the incident light under the irradiation of polarized ultraviolet light. Photoinduced optical anisotropy of the AZO-MWCNT film was dominated by the enhanced dipole transition of the nanotube axis parallel to the incident light and the decreased transition perpendicular to light. The unique anisotropy induced by the photo-orientation of azobenzene chromophore provides insight into the polarized optical properties of carbon nanotubes. [ABSTRACT FROM AUTHOR]

Published
2007
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108. Carrier transport in a columnar mesophase of discotic liquid crystalline organic semiconductors with specific intermolecular interactions

Author

Miyake, Yasuo, Monobe, Hirosato, Ping, Hu, Zhao, Ke-Qing, Fujii, Akihiko, Ozaki, Masanori, and Shimizu, Yo

Subjects
有機半導体, Discotic liquid crystal, キャリア移動度, ディスコチック液晶, Columnar mesophase, Carrier mobility, Organic semiconductor, カラムナー相
Abstract

液晶性半導体は高秩序配向相においてアモルファスシリコンに匹敵するキャリア移励度が報告されているが、更なるキャリア移動度の向上が望まれている。キャリアのホッピング効率を上昇させる為には、液晶相における運動性の制御が重要である。本研究では、代表的な液晶性半導体であるトリフェニレンに親フッ素／疎フッ素相互作用及び分子間水素結合基を導入し、カラムナー相におけるキャリア移動度をTime-Of-Flight法で測定した。, Though high carrier mobility comparable to that of amorphous silicon (-10―1c m2Ns) was shown in highly ordered liquid crystal semiconductors, it was still required to raise the mobility in mesophase. Based on the theory, control of molecular dynamics in liquid crystalline states is essentially an important challenge to increase the hopping efficiency for carriers. In this work, the carrier mobility behavior of typical discotic liquid crystalline semiconductors triphenylenes, which were chemically modified to work intermolecular specific interactions such as fluorophobic/philic and hydrogen-bond interactions were studied for the columnar mesophase by a Time-Of-Flight technique.

Published
2009

117. Nobel Optical Properties of Conducting Polymer/Nano-structured ZnO System

Author

Yoshino, Katsumi, Tanaka, Senku, Fujii, Akihiko, Ozaki, Masanori, and Fujita, Yasuhisa

Subjects
電子移動, Condensed Matter::Other, Physics::Optics, Nano-particle, ナノ粒子, Condensed Matter::Soft Condensed Matter, Electron transfer, 蛍光増強, Condensed Matter::Materials Science, 蛍光消光, エネルギー移動, Computer Science::Emerging Technologies, Energy transfer, Quenching, ZnO, Photoluminescence, Conducting Polymer, 導電性高分子
Abstract

Quenching of photoluminescence of conducting polymer and enhancement of photoluminescence of ZnO nano-particles were observed in conducting polymer/ZnO nano-particle system, which is discussed in terms of electron transfer and excited state energy transfer between conducting polymer and ZnO nano-particles., 導電性高分子/ZnOナノ粒子複合体において導電性高分子の蛍光の消光とZnOの蛍光の増強が見出され、光励起された導電性高分子とZnOナノ粒子の間の電子移動とエネルギー移動を考慮に入れて説明された。

Published
2007

142. Si、Ge原子含有置換基を有するポリジフェニルアセチレンの発光特性

Author

Nishihara, Yusuke, Hidayat, Rahmat, Fujii, Akihiko, Ozaki, Masanori, Yoshino, Katsumi, Karim, M. Abdul S., and Masuda, Toshio

Subjects
disubstituted polyacetylenes, polyacetylenes, photoluminescence, conducting polymers, electroluminescence
Abstract

Optical properties such as photoluminescence (PL) and electro luminescence (EL) of poly(diphenylacetylene)(PDPA) derivatives with substituents containing silicon and germanium atoms have been studied. PDPA derivatives exhibited highly efficient PL and PL spectral narrowing originated from amplified spontaneous emission (ASE) in the case of high excitation. The peak wavelength of PL spectra depends on the positions of substitution and the atoms(silicon or germanium) of the substitution. EL has also been observed from PDPA derivatives sandwiched between magnesium-silver alloy cathode and indium-tin-oxide anode. PL decay has also been confirmed to be dependent on the position of the substituents and the hetero-atoms in the substituents. These characteristics have been interpreted in terms of the effects of substituent properties and their positions on the conformation of the main chains and electronic energy schemes., SiやGe原子を含む置換基を有するポリジフェニルアセチレン(PDPA)の電界発光(EL))や蛍光(PL)及び高強度励起時における蛍光スペクトルナローイングのような光学的特性については以前から研究されている。このようなPDPA は高い蛍光効率を示し、蛍光のピーク波長は置換基の原子の種類(SiやGe)及び、位置に大きく依存している。また、陽極をITO、陰極をMgAgとしてサンドイッチ構造としたELも観測されている。蛍光寿命においても同様に、置換基の原子の種類及び、位置に大きく依存している。これらの特性は置換基の性質や主鎖のコンフォメーション及び、エネルギーバンド図によって説明される。

Published
2001

150. 星状分岐型有機シリコン化合物の光学的性質

Author

Yoshino, Katsumi, Sonoda, Tooru, Hidayat, Rahmat, Fujii, Akihiko, Ozaki, Masanori, Schneider, Wolfgang, Lee, Kyung Koo, Naka, Akinobu, and Ishikawa, Mitsuo

Subjects
silanylene, photoluminescence, organosilicon compounds, oligothienylene, electroluminescence, X-ray diffraction
Abstract

Optical absorption and photoluminescence (PL) spectra, time-resolved PL and electroluminescence (EL) in star-like branched organosilicon compounds have been found to be dependent on the length and number of oligothienylene units in each arm. Films of the organosilicon compounds with two oligothienylene unit in each arm have been found to exhibit two PL peaks but a single peak in those with one oligothienylene unit. Origin of the PL peaks is discussed in tenms of the disorder in films and localized state related to the disorders in the film., 星状分岐型有機シリコン化合物の光学吸収、蛍光(ＰＬ)、時間分解ＰＬ、電界発光(ＥＬ)において、分子中のオリゴチエニレンの長さや数についての依存性を明らかにした。オリゴチエニレンユニットが二つある場合、ＰＬピークが二つ存在し、オリゴチエニレンユニットが一つの場合ＰＬピークは一つである。ＰＬピークについては、フィルム中の欠陥や欠陥による局在状態により発現すると考えられる。

Published
1999

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