Recent advances of nonfullerene acceptors in organic solar cells

Organic solar cells (OSCs) have acquired dramatic progresses during the past several years due to low-cost, light weight, mechanical flexibility, and printable fabrication. Simultaneously, the nonfullerene acceptors (NFAs) exert significant influence on widening the absorption and enhancing the stability and power conversion efficiency (PCE) of OSCs. Consequently, NFAs have attracted increasing attention on account of some inherent superiorities. The PCE of OSCs has been elevated to over 20%. Small-molecule and polymer NFAs play a crucial role in OSCs. A summary based on NFAs in OSCs has been concluded. Firstly, the development and working principles of NFAs-based OSCs are briefly summarized; secondly, the characteristics of small molecule and polymer NFAs are introduced. Finally, the evolution and prospects of NFAs are also discussed.