Improved stability of organic field-effect transistor performance in oligothiophenes including β-isomers
摘要:
Dialkyl quarter-and quinquethiophenes end-capped with beta-connected thiophenes are prepared, and the field-effect transistor (FET) properties are investigated. Molecular orbital calculation as well as the redox and optical measurements indicate that the beta-isomers have low-lying HOMO levels and large energy gaps compared with the alpha-isomers. Molecular packing of the dihexylquaterthiophene with beta-isomers consists of a typical herringbone motif analogous to the alpha-isomers. In the single crystal, the alkyl chains are extending in the tilted directions from the core molecular plane, but straightly extending in the thin films, resulting in even more perpendicular molecular arrangement to the substrate than the alpha-isomers. These beta-isomers show p-type FET performance comparable to the corresponding alpha-isomers, whereas all new oligothiophenes show air stability better than the corresponding alpha-isomers. In particular, dihexylquinquethiophene with beta-isomers has shown significantly improved air stability maintained over 270 days. This stabilization effect is ascribed to the low-lying HOMO level and the dense packing realized by perpendicular molecular arrangement. (C) 2012 Elsevier Ltd. All rights reserved.
Improved stability of organic field-effect transistor performance in oligothiophenes including β-isomers
作者:Minoru Ashizawa、Takuro Niimura、Yan Yu、Kazuma Tsuboi、Hidetoshi Matsumoto、Ryo Yamada、Susumu Kawauchi、Akihiko Tanioka、Takehiko Mori
DOI:10.1016/j.tet.2012.02.004
日期:2012.4
Dialkyl quarter-and quinquethiophenes end-capped with beta-connected thiophenes are prepared, and the field-effect transistor (FET) properties are investigated. Molecular orbital calculation as well as the redox and optical measurements indicate that the beta-isomers have low-lying HOMO levels and large energy gaps compared with the alpha-isomers. Molecular packing of the dihexylquaterthiophene with beta-isomers consists of a typical herringbone motif analogous to the alpha-isomers. In the single crystal, the alkyl chains are extending in the tilted directions from the core molecular plane, but straightly extending in the thin films, resulting in even more perpendicular molecular arrangement to the substrate than the alpha-isomers. These beta-isomers show p-type FET performance comparable to the corresponding alpha-isomers, whereas all new oligothiophenes show air stability better than the corresponding alpha-isomers. In particular, dihexylquinquethiophene with beta-isomers has shown significantly improved air stability maintained over 270 days. This stabilization effect is ascribed to the low-lying HOMO level and the dense packing realized by perpendicular molecular arrangement. (C) 2012 Elsevier Ltd. All rights reserved.