Preparation of Dual-Asymmetric Acceptors via Selenium Substitution Combined with Terminal Group Optimization Strategy for High Efficiency Organic Solar Cells
Haoran Yin, Yongjie Cui, Dong Chen, Siqi Liu, Tuhong Wu, Mengqi Yu, Long Ye, Aihui Liang, Yiwang Chen
Abstract
Improving both the open-circuit voltage ( V OC ) and short-circuit current density ( J SC ) through the development of photovoltaic materials to achieve high power conversion efficiency (PCE) is critical and a significant challenge for organic solar cells (OSCs). Here, we designed novel dual-asymmetric acceptors A-SSe-TCF and A-SSe-LSF by simultaneously asymmetrically regulating the backbone and terminal groups and investigated their synergistic effects on photovoltaic performance in comparison with the monoasymmetric acceptor A-SSe-4F. The dual-asymmetric acceptors exhibit broader spectral absorption and larger half-molecule dipole moment differences, which favored the enhancement of J SC and the reduction of energy loss ( E loss ). Among the binary blends, PM6:A-SSe-TCF exhibits superior phase separation, vertical phase distribution morphology, and more ordered π–π stacking compared to PM6:A-SSe-LSF and PM6:A-SSe-4F. As a result, OSCs based on PM6:A-SSe-TCF achieved a higher PCE of 18.53% with both higher V OC and J SC due to the suppressed nonradiative recombination and enhanced charge extraction capabilities. Furthermore, by incorporating A-SSe-TCF as the third component, the PM6:L8-BO:A-SSe-TCF-based device achieves a champion PCE of 19.73% without V OC loss on account of the decrement of E loss . The novel dual-asymmetric strategy provides new insights into the molecular design and the improvement of PCE for OSCs.