以二（2-辛基十二烷氧基）苯并二噻吩（ODBDT）为供体单元，分别与受体单元二噻吩苯并噻二唑（DTBT）和二氟代二噻吩苯并噻二唑（DTffBT）共聚，合成了两种具有给-受体（D-A）结构的共轭聚合物PODBDT-DTBT和PODBDT-DTffBT。利用紫外-可见吸收光谱、循环伏安法研究了聚合物的光物理与电化学性能，并通过光伏性能测试研究了氟原子对聚合物太阳能电池的影响规律。结果表明，氟原子的引入使得聚合物的光学带隙变窄，溶解性变差；基于PODBDT-DTBT或PODBDT-DTffBT与PC71BM共混制备的本体异质结太阳能电池，光电转化效率分别为3.01%和2.00%。
Abstract
Two donor-acceptor (D-A) conjugated copolymers, namely PODBDT-DTBT and PODBDT-DTffBT, have been synthesized based on a di-(2-octyldodecyloxy)benzo［1,2-b:4,5-b′］dithiophene(ODBT) donor unit and 4,7-di(thiophen-2-yl)benzo (DTBT) or 5,6-difluoro-4,7-di(thiophen-2-yl)benzo (DTffBT) acceptor units. The photophysical and electrochemical properties of the two copolymers were investigated. The effect of fluorine atoms on the photovoltaic properties of the copolymers and the corresponding bulk heterojunction (BHJ) devices were studied. The results showed that fluorine substitution reduced the solubility of the material and had an adverse effect on the film-forming performance, but lowered the bandgap of the resulting polymer. BHJ solar cells based on PODBDT-DTBT or PODBDT-DTffBT blended with PC71BM demonstrated power conversion efficiencies of 3.01% and 2.00%, respectively, under AM 1.5G illumination (100 mW/cm2).
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