Enhancement of photovoltaic performance by increasing conjugation of the acceptor unit in benzodithiophene and quinoxaline copolymers
作者:Tong Hu、Liangliang Han、Manjun Xiao、Xichang Bao、Ting Wang、Mingliang Sun、Renqiang Yang
DOI:10.1039/c4tc01440e
日期:——
Copolymers based on benzodithiophene and quinoxaline, represented by 4,8-bis(5-(3,4,5-tris(octyloxy)phenyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene (TOBDT) and 2,3-diphenyl-5,8-di(thiophen-2-yl)quinoxaline (TQ1) or 10,13-bis(4-(2-ethylhexyl)thiophen-2-yl)dibenzo[a,c]phenazine (TQ2), were synthesized via a Stille coupling reaction. By increasing the conjugation in the TQ2 unit, the polymer based on TQ2 showed a narrower band gap (Eg), a lower highest occupied molecular orbital energy level and enhanced interchain π–π interactions. Polymer solar cells based on TQ2 showed a simultaneous enhancement of the open-circuit voltage (Voc), short-circuit current density (Jsc) and fill factor (FF) compared with polymer solar cells based on the TQ1 polymer. A good power conversion efficiency of 4.24% was achieved by solar cells based on the TQ2 polymer and [6,6]-phenyl-C71-butyric acid methyl ester composite. These preliminary results indicate that increasing the acceptor unit (quinoxaline) conjugation is an effective way of improving the performance of polymer solar cells.
基于苯并二噻吩和喹喔啉的共聚物,以4,8-双(5-(3,4,5-三(辛氧基)苯基)噻吩-2-基)苯并[1,2-b:4,5-b'表示]二噻吩 (TOBDT) 和 2,3-二苯基-5,8-二(噻吩-2-基)喹喔啉 (TQ1) 或 10,13-双(4-(2-乙基己基)噻吩-2-基)二苯并[ a,c]吩嗪 (TQ2) 通过 Stille 偶联反应合成。通过增加TQ2单元的共轭,基于TQ2的聚合物表现出更窄的带隙(Eg)、更低的最高占据分子轨道能级和增强的链间π-π相互作用。与基于TQ1聚合物的聚合物太阳能电池相比,基于TQ2的聚合物太阳能电池的开路电压(Voc)、短路电流密度(Jsc)和填充因子(FF)同时提高。基于TQ2聚合物和[6,6]-苯基-C71-丁酸甲酯复合材料的太阳能电池实现了4.24%的良好功率转换效率。这些初步结果表明,增加受体单元(喹喔啉)共轭是提高聚合物太阳能电池性能的有效途径。