A-D-A′-D-A-type non-fused ring electron acceptors for organic solar cells and photodetectors

The A-D-A′-D-A-type non-fused ring electron acceptors (NFREAs), consisting of electron-donating unit (D) as the bridge to link electron-accepting units (A and A′), have emerged as promising electron acceptors for organic solar cells (OSCs) and organic photodetectors (OPDs). As the units are linked by the carbon-carbon single bonds, these electron acceptors generally possess feasible synthesis and tunable optoelectronic properties. Herein, the recent progress of A-D-A′-D-A-type NFREAs is reviewed, including molecular design, device performance, structure-property relationships, and their applications in OSCs and OPDs. Finally, we discuss the challenges and propose the perspectives for the further development of A-D-A′-D-A-type NFREAs.