Three new copolymers (PT-TPA, PT-DTBT and PT-DTBTTPA) based on benzo[1,2-b:4,5-b]dithiophene (BDT) and thiophene with different conjugated side chains (di(p-tolyl)phenylamine (TPA), 4,7-dithien-5-yl-2,1,3-benzothiadiazole (DTBT) and DTBT-TPA) were synthesized via Stille coupling polymerization. The TPA and the DTBT were introduced to improve the hole-transport ability and broaden the absorption spectrum. The effects of different conjugated side groups on thermal, optical, electrochemical, hole-transporting and photovoltaic properties of these copolymers were investigated. Field effect results show that the copolymer PT-DTBTTPA containing TPA and DTBT in the side chain showed the highest hole mobility. The three copolymers exhibit deep-lying HOMO energy levels, which were effectively tuned by changing the side groups. Photovoltaic cells were fabricated with the synthesized copolymers as electron donors and [6,6]-phenyl-C-butyric acid methyl ester (PCBM) as the electron acceptor. Bulk heterojunction polymer solar cells based on PT-DTBT and PT-DTBTTPA showed promising power conversion efficiencies of 5.50% and 5.16%, respectively.
三种新型共聚合物(
PT-
TPA、
PT-DTBT和
PT-DTBT
TPA)基于苯并[1,2-b:4,5-b]二
硫噻吩(BDT)和不同的共轭侧链(对甲基苯基胺(
TPA)、4,7-二
噻吩-5-基-2,1,3-
苯并噻唑(DTBT)和DTBT-
TPA)通过斯蒂尔耦合聚合反应合成。引入
TPA和DTBT是为了改善载流子传输能力并拓宽吸收光谱。研究了不同共轭侧基对这些共聚合物的热、电光、电子
化学、载流子传输及光伏性能的影响。场效应结果表明,侧链中含有
TPA和DTBT的共聚合物
PT-DTBT
TPA展现出最高的孔迁移率。这三种共聚合物具有较深的HOMO能级,通过改变侧基有效调节。采用合成的共聚合物作为电子供体,以[6,6]-苯基-C-
丁酸甲酯(PCBM)作为电子受体制作了光伏电池。基于
PT-DTBT和
PT-DTBT
TPA的薄膜异质结聚合物太阳能电池分别显示出有前景的光电转换效率,达到5.50%和5.16%。