A–D–A small molecule acceptors with ladder-type arenes for organic solar cells

A–D–A small molecule acceptors (SMAs) have attracted much attention due to their merits of strong absorption, low bandgap, relatively high electron mobility and suitable miscibility with donors. Benefitting from the rapid development of A–D–A SMAs, the efficiency of organic solar cells (OSCs) has been improved significantly, which has caused excitement in the OSC community. In this review, we collect the reported high-efficiency A–D–A SMAs according to the ring number of the ladder-type donor core in their centers; we also summarize the evolution process of these molecular structures and their photovoltaic parameters. Our aim is to afford an overview of A–D–A SMAs and help readers to obtain a deep understanding of these compounds.