Thiazole-Functionalized Terpolymer Donors Obtained via Random Ternary Copolymerization for High-Performance Polymer Solar Cells
Zhihui Liao, Ke Yang, Licheng Hou, Jun Li, Jie Lv, Ranbir Singh, Manish Kumar, Qianqian Chen, Xiyue Dong, Tongle Xu, Chao Hu, Tainan Duan, Zhipeng Kan, Shirong Lu, Zeyun Xiao
Abstract
Random ternary copolymerization is a simple but effective strategy to develop new efficient polymer donors for polymer solar cell application. Herein, a series of new copolymers, OPz1, OPz2, OPz3, and OPz4, containing varying fraction of ester-substituted thiazole (E-Tz) as the third component to the widely studied PM6 copolymer, were synthesized. Incorporation of the E-Tz unit is found to significantly improve the molecular planarity, energy levels, and light-harvesting range of the polymer donors. Impressively, subtle regulation of the E-Tz content realized a dramatic enhancement of all the device parameters with a champion power conversion efficiency of 16.28% achieved with the OPz1:Y6 device. The performance improvement was attributed to the reduced energy loss, the downshifted energy levels and optimized charge transport. Our results demonstrated that the E-Tz unit is a promising building block, and random ternary copolymerization is a powerful strategy for photovoltaic materials development.