Geometries, Electronic Couplings, and Hole Dissociation Dynamics of Photoinduced Electron–Hole Pairs in Polyhexylthiophene–Fullerene Dyads Rigidly Linked by Oligophenylenes

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• 作者：Taku Miura ; Ran Tao ; Sho Shibata ; Tomokazu Umeyama ; Takashi Tachikawa ; Hiroshi Imahori ; Yasuhiro Kobori
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：May 11, 2016
• 年：2016
• 卷：138
• 期：18
• 页码：5879-5885
• 全文大小：399K
• 年卷期：0
• ISSN：1520-5126

文摘

To shed a light on fundamental molecular functions of photoinduced charge conductions by organic photovoltaic materials, it is important to directly observe molecular geometries of the intermediate charges just after the photoinduced electron-transfer reactions. However, highly inhomogeneous molecular environments at the bulk heteojunction interfaces in the photoactive layers have prevented us from understanding the mechanism of the charge conductions. We have herein investigated orbital geometries, electronic couplings, and hole-dissociation dynamics of photoinduced charge-separated (CS) states in a series of poly(3-hexylthiophene)–fullerene linked dyads bridged by rigid oligo-p-phenylene spacers by using time-resolved EPR spectroscopy. It has been revealed that one-dimensional intramolecular hole-dissociations exothermically take place from localized holes in initial CS states, following bridge-mediated, photoinduced charge-separations via triplet exciton diffusions in the conjugated polymer-backbones. This molecular wire property of the photoinduced charges in solution at room temperature demonstrates the potential utility of the covalently bridged polymer molecules applied for the molecular devices.