Trifluoromethyl Group-Modified Non-Fullerene Acceptor toward Improved Power Conversion Efficiency over 13% in Polymer Solar Cells
Chao Yao, Jiajun Zhao, Yanan Zhu, Bin Liu, Chaoyi Yan, Dmitrii F. Perepichka, Hong Meng
Abstract
Herein, we report a new molecule structure modification strategy for non-fullerene small-molecule electron acceptors (NFAs) for solar cells through trifluoromethylation of end-capping groups. The synthesized trifluoromethylated acceptor ITCF3 exhibits narrower band gap, stronger light absorption, lower molecular energy levels, and better electron transport property compared to the reference NFA without the trifluoromethyl group (ITIC). Bulk heterojunction solar cells based on ITCF3 combined with the PM6 polymer donor exhibit a significantly improved power conversion efficiency of 13.3% compared with the ITIC-based device (8.4%). This work reveals great potential of trifluoromethylation in the design of efficient photovoltaic acceptor materials.