Molecular Design and Application of a Photovoltaic Polymer with Improved Optical Properties and Molecular Energy Levels
作者:Huifeng Yao、Hao Zhang、Long Ye、Wenchao Zhao、Shaoqing Zhang、Jianhui Hou
DOI:10.1021/acs.macromol.5b00649
日期:2015.6.9
(E)-5-(2-(5-(Alkylthio)thiophen-2-yl)vinyl)thiophene-2-yl functional groups were introduced onto 4- and 8-positions of BDT units, and this building block was used to construct a new derivative polymer of PTB7, named as PBT-TVT. Benefiting from the prolonged conjugation of the conjugated side groups on BDT units, the optical absorption property of PBT-TVT can be improved greatly compared to that of PTB7, so an inspiring result of 7.67% was obtained by using PBT-TVT as the donor and PC61BM as the acceptor in polymer solar cells (PSCs), which is much higher than that of the PTB7:PC61BM-based device and also one of the highest results for PSCs with PC61BM. In electrochemical cyclic voltammetry (CV) measurements, PBT-TVT showed a deeper HOMO level than PTB7 so the device based on the former exhibits higher open circuit voltage than the latter. Moreover, in comparison with PTB7, the new polymer PBT-TVT exhibited stronger interchain pi-pi interaction and thus higher hole mobility. Overall, the results in this work indicated that PBT-TVT is a promising donor polymer, and the strategy used in this work will be beneficial for molecular design of polymer photovoltaic materials for large-scale production of PSCs.
(E)-5-((5-甲基硫代苯乙烯-2-基)丁二烯-2-yl) thiophene-2-yl基团被引入到 BDT 单元的 4- 和 8- 位,作为构建块构建了新的 PTD 型聚合物共聚物 PBT-TVT。借助 BDT 单元上的共轭基团及侧链共轭基团的伸长共轭作用,PBT-TVT 所具有的光学吸收性能较之 PTB7 型,极大地得到了提升。在聚能太阳能电池(PSCs)的实验中,以 PBT-TVT 作为供体,采用 PC61BM 作为接受体,获得了 7.67% 的光电转化效率,较基于 PTB7-PC61BM 型装置明显高于前者,且数值并列目前基于 PC61BM 的聚能太阳能电池中最高之一。再者,在电化学循环伏安特性(CV)测量中,PBT-TVT 的 HOMO 能级较 PTB7 更为深入,因而基于 PBT-TVT 的聚能太阳能电池工作装置的开路电压明显更高;同时,相比 PTB7,PBT-TVT 新聚合物显示出较强的空间链间共轭作用及由此产生的高质子迁移率。综上所述,本研究中所取得的结果表明,PBT-TVT 是有望作为供体聚合物的一种,且本研究采用的方法对于后续分子设计聚能光伏材料生产大尺寸聚能太阳能电池具有很好的指导意义。