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Okamoto T.,University of Tokyo | Okamoto T.,Institute of Scientific and Industrial Research ISIR | Nakahara K.,University of Tokyo | Saeki A.,Osaka University | And 6 more authors.
Chemistry of Materials | Year: 2011

5-Perfluorophenyl-11-phenyltetracene (FPPT) having both aryl (Ar) and perfluoroaryl (FAr) groups has been designed and synthesized to obtain well-defined n-n stacking structure of the tetracene core. Single-crystal X-ray analyses as well as photoconductivity and hole mobility measurements revealed that this strategy is promising for enhancement of the charge carrier properties. © 2011 American Chemical Society.

Suzuki T.,University of Tokyo | Okamoto T.,University of Tokyo | Okamoto T.,Institute of Scientific and Industrial Research ISIR | Saeki A.,Osaka University | And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2013

Nanowires of tetracene dicarboxylic imide disulfide with an N-hexyl substituent (HexylTIDS) were successfully constructed in composite thin film containing poly(3-hexylthiophene) (P3HT). The nanowire structures were investigated by atomic force microscopy and scanning electron microscopy. The photoconductivity of the composite films was evaluated by time-resolved microwave conductivity measurements, revealing that the film containing a 1:1 w/w ratio of HexylTIDS and P3HT exhibited the highest photoconductivity (2.1 × 10-7 m2/(V s)). The intermolecular interactions of HexylTIDS molecules were important in nanowire formation. These results suggest a one-step method for fabricating small-molecule-based nanowires in composite films from a blended solution. This type of composite film, and its fabrication method, will be useful for developing organic thin-film photoelectronic devices. © 2013 American Chemical Society.

Matsuo Y.,University of Tokyo | Oyama H.,University of Tokyo | Soga I.,University of Tokyo | Soga I.,Mitsubishi Group | And 6 more authors.
Chemistry - An Asian Journal | Year: 2013

The efficient nucleophilic addition of aryl Grignard reagents (aryl=4-MeOC6H4, 4-Me2NC6H 4, Ph, 4-CF3C6H4, and thienyl) to C60 in the presence of DMSO produced 1,2-arylhydro[60]fullerenes after acid treatment. The reactions of the anions of these arylhydro[60] fullerenes with either dimethylphenylsilylmethyl iodide or dimethyl(2- isopropoxyphenyl)silylmethyl iodide yielded the target compounds, 1-aryl-4-silylmethyl[60]fullerenes. The properties and structures of these 1-aryl-4-silylmethyl[60]fullerenes (aryl=4-MeOC6H4, thienyl) were examined by electrochemical studies, X-ray crystallography, flash-photolysis time-resolved microwave-conductivity (FP-TRMC) measurements, and electron-mobility measurements by using a space-charge-limited current (SCLC) model. Organic photovoltaic devices with a polymer-based bulk heterojunction structure and small-molecule-based p-n and p-i-n heterojunction configurations were fabricated by using 1-aryl-4-silylmethyl[60]fullerenes as an electron acceptor. The most efficient device exhibited a power-conversion efficiency of 3.4 % (short-circuit current density: 8.1 mA/ cm2, open-circuit voltage: 0.69 V, fill factor: 0.59). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Okamoto T.,University of Tokyo | Okamoto T.,Institute of Scientific and Industrial Research ISIR | Suzuki T.,University of Tokyo | Tanaka H.,University of Tokyo | And 3 more authors.
Chemistry - An Asian Journal | Year: 2012

We have designed and synthesized a new donor/acceptor-type tetracene derivative by the introduction of dicarboxylic imide and disulfide groups as electron-withdrawing and -donating units, respectively. The prepared compounds, tetracene dicarboxylic imide (TI) and its disulfide (TIDS) have high chemical and electrochemical stability as well as long-wavelength absorptions of up to 886 nm in the thin films. The crystal packing structure of TIDS molecules features face-to-face π-stacking, derived from dipole-dipole interactions. Notably, TIDS exhibited ambipolar properties of both electron-donating and -accepting natures in p-n and p-i-n heterojunction organic thin-film photovoltaic devices. Accordingly, TI and TIDS are expected to be promising compounds for designing new organic semiconductors.

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