Solution processable D-A small molecules for bulk-heterojunction solar cells

Solution processable small molecules have been widely applied for photovoltaic (PV) devices in recent years because they show strong absorption properties, and they can be easily purified and deposited onto flexible substrates at low cost. Introducing different donor and acceptor groups to construct donor-acceptor (D-A) structure small molecules has proved to be an efficient way to improve the properties of organic solar cells (OSCs). This review deals with the recent progress of solution processable D-A structure small molecules and discusses the key factors affecting the properties of OSCs based on D-A structure small molecules: sunlight absorption, charge transport and the energy level of the molecules. Then we give some suggestions for designing new solution processable D-A structure small molecules for high performance OSCs.