Organic photovoltaics (OPVs) have developed rapidly since the advent of fused-ring electron acceptors (FREAs). FREAs bearing bulky fused-ring cores, end-capped with electron-withdrawing groups, present advantages such as broad absorption, tunable frontier orbital levels, and good thermal stability. Recent breakthroughs demonstrate that FREA-based OPVs have achieved more than 17% efficiency, among which the end groups (EGs) of 1,1-dicyanomethylene-3-indanone (IC) and derivatives are critical for the performance enhancement. To date, more than 50 IC derivatives have been reported to construct high-performance FREA-based OPVs. In this review, we first introduce the chemical structure and synthesis route of the IC group. We discuss and classify the recent progress of FREAs based on IC and its derivatives, as well as the impact of IC on the morphology. We consider the issues the IC EGs face, including stability, isomerism, and EG redistribution, finally proposing some future directions for FREAs based on IC and its derivatives.

自稠环电子受体（FREA）问世以来，有机光伏（OPV）发展迅速。带有笨重的稠环核并用吸电子基团封端的FREA具有许多优点，例如吸收范围广，边界轨道可调，以及良好的热稳定性。最近的突破表明，基于FREA的OPV的效率已超过17％，其中1,1-二氰亚甲基-3-茚满酮（IC）和衍生物的端基（EG）对于提高性能至关重要。迄今为止，已经报道了50多种IC衍生物可构建基于FREA的高性能OPV。在这篇综述中，我们首先介绍了IC基团的化学结构和合成路线。我们讨论和分类基于IC及其衍生物的FREAs的最新进展，以及IC对形态的影响。