Charge Generation and Recombination in Fullerene-Attached Poly(3-hexylthiophene)-Based Diblock Copolymer Films

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• 作者：Shunsuke Yamamoto ; Hiroaki Yasuda ; Hideo Ohkita ; Hiroaki Benten ; Shinzaburo Ito ; Shoji Miyanishi ; Keisuke Tajima ; Kazuhito Hashimoto
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：May 22, 2014
• 年：2014
• 卷：118
• 期：20
• 页码：10584-10589
• 全文大小：317K
• 年卷期：v.118,no.20(May 22, 2014)
• ISSN：1932-7455

文摘

The charge generation and recombination dynamics in fullerene-attached poly(3-hexythiophene) (P3HT)-based diblock copolymer were studied in comparison with those in blend films of P3HT and a fullerene derivative (PCBM) in order to understand the potential advantage of diblock copolymer-based polymer solar cells. Upon photoexcitation, P3HT singlet excitons are promptly converted to P3HT polarons with a time constant of 30 ps in both P3HT-PCBM diblock copolymer and P3HT/PCBM blend films. This similar charge generation dynamics is indicative of analogous phase-separated morphology both in these films on a scale of nanometers. After the charge generation, a part of polarons in disorder phases geminately recombine to the ground state in diblock copolymer films, while no geminate recombination is observed in blend films. This geminate recombination loss is probably due to defects of phase-separated structures in diblock copolymer films. On the other hand, charge carrier lifetime is as long as 15 渭s in diblock copolymer films. Such a long carrier lifetime may result in a relatively high fill factor in P3HT-PCBM copolymer films. Finally, we discuss the overall device performance in terms of phase-separated structures.