Alkyl Side Chain Impact on the Charge Transport and Photovoltaic Properties of Benzodithiophene and Diketopyrrolopyrrole-Based Copolymers

详细信息    查看全文

• 作者：Zhao Li ; Yanguang Zhang ; Sai-Wing Tsang ; Xiaomei Du ; Jiayun Zhou ; Ye Tao ; Jianfu Ding
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：September 15, 2011
• 年：2011
• 卷：115
• 期：36
• 页码：18002-18009
• 全文大小：987K
• 年卷期：v.115,no.36(September 15, 2011)
• ISSN：1932-7455

文摘

To investigate the side chain effect on the photovoltaic performance of conjugated copolymers with alternating electron push鈥損ull structures, three alternating copolymers (O鈥揌D, BO鈥揃O, and PU鈥揙) of benzodithiophene and dithienyldiketopyrrolopyrrole were designed and synthesized. They were nomenclated based on the side chains on the benzodithiophene (BDT) and the diketopyrrolopyrrole (DPP) units, which are octyl (O) and 2-hexyldecyl (HD); 3-butyloctyl (BO), and 2-butyloctyl (BO): and 3-pentylundecyl (PU) and octyl (O) groups, respectively. The total C number of the side chains in each repeat unit was kept at 48 to control the dilute effect. The solubility, optical, and electrochemical properties, and crystalline structure of the polymers were depended on the combination of these linear or branched alkyl chains. Thin film transistor (TFT) characterization showed that PU鈥揙 had the best hole mobility up to 1.6 脳 10^鈥? cm²V^鈥? s^鈥?. The best photovoltaic performance was observed from O鈥揌D with power conversion efficiency (PCE) up to 4.1%. However, it only showed a modest hole mobility of 3.8 脳 10^鈥? cm²V^鈥? s^鈥?, about 4-fold lower than PU鈥揙. This dramatically different performance of these polymers for TFT and photovoltaic devices was explained by the interaction at the interface of the polymer electron donor and the PCBM acceptor domains.