Introducing Four 1,1-Dicyanomethylene-3-indanone End-Capped Groups as an Alternative Strategy for the Design of Small-Molecular Nonfullerene Acceptors

Linear A–D–A or A−π–D−π–A architectures are predominant in the design of promising nonfullerene acceptors (NFAs), which promoted the rapid progress of organic solar cells. However, utilization of four electron-accepting units (A) to construct four-armed NFAs is rarely reported and the relationship of structure–properties–performance is unclear. In this study, we designed and synthesized a novel acceptor ( A401 ) with an (AA)−π–D−π–(AA) configuration, where four 1,1-dicyanomethylene-3-indanone groups were used as the end-capped segments. When A401 was paired with a classic p-type polymer PBDB-T, a power conversion efficiency of 7.54% could be achieved, which was much higher than that of the reported two-armed analogue of DC-IDT-2T (3.93%). The improved photovoltaic performance of A401 should be ascribed to the high electron affinity. Our results indicate introducing more end-capped electron-accepting units is a simple and effective alternative strategy for the design of promising NFAs. Our conceptualized molecular architecture will encourage further research of high-performance multiarmed NFAs.