High‐Efficiency Binary and Ternary Organic Solar Cells Based on Novel Nonfused‐Ring Electron Acceptors

Abstract In this study, three nonfused‐ring electron acceptors (2TT, 2TT‐C6‐F, and 2TT‐C11‐F) with the same steric hindrance groups (2,4,6‐tripropylbenzene) are designed and synthesized and the impact of electron‐withdrawing and lateral alkyl side chains on the performance of binary and ternary organic solar cells (OSCs) is explored. For the binary OSCs, 2TT‐C11‐F with IC‐2F terminal groups and lateral undecyl side chains display a red shifted absorption spectrum and suitable energy levels, and the corresponding blend film exhibits appropriate phase separation and crystallinity. Thus, binary OSCs based on 2TT‐C11‐F achieve an impressive power conversion efficiency of 13.03%, much higher than the efficiencies of those based on 2TT (9.68%) and 2TT‐C6‐F (12.11%). In the ternary OSCs, 2TT with CC terminal groups and lateral hexyl side chains exhibit complementary absorption and cascade energy levels with a host binary system (D18:BTP‐eC9‐4F). Hence, the ternary OSCs based on 2TT achieve a remarkable efficiency of 19.39%, ranking among the highest reported values. The research yields comprehensive 2TT‐series nonfused‐ring electron acceptors, demonstrating their great potential for the fabrication of high‐performance binary and ternary OSCs.