The Design and Performance of Non-Fused Ring Acceptors for Organic Solar Cells with High Power Conversion Efficiency

Organic solar cells (OSCs) have gained widespread applications in fields such as wearable devices, portable power and building-integrated photovoltaics because of their inherent flexibility, lightweight, and potential to lower production costs. Among the various components of organic solar cells, electron acceptor materials are one of the essential factors in attaining high power conversion efficiency (PCE). Traditionally, fullerene-based acceptors dominated the field, but their limitations in tunability and performance have led to the rise of non-fullerene acceptors (NFAs), particularly non-fused ring acceptors (NFREAs). NFREAs have attracted significant attention in recent years due to their easily adjustable molecular structures, simplified synthesis processes, and lower costs compared to fused-ring acceptors (FREAs). This review provides a detailed introduction to the development history and latest advancements achieved in NFREAs, with a focus on their classification based on different molecular backbones. Some key modification strategies are also discussed, offering insights into future directions for designing high-performance non-fused ring acceptors in OSCs.