A conjugated donor-acceptor block copolymer enables over 11% efficiency for single-component polymer solar cells

Covalently linking donor (D) and acceptor (A) moieties into single material can be an effective strategy to enable efficient exciton dissociation and charge generation. Herein, we synthesized a conjugated D-A block copolymer (PBDB-T-b-PYT), in which a donor block (PBDB-T) was connected to an acceptor block (PYT). Compared with the bulk heterojunction (BHJ) blend mixture containing PBDB-T and PYT with high molecular weights, more efficient exciton dissociation and charge transfer (CT) were observed in the single-component PBDB-T-b-PYT films. Impressively, a single-material organic solar cell (SMOSC) fabricated from PBDB-T-b-PYT alone exhibited a power conversion efficiency (PCE) of 11.32% and a certificated PCE of 10.8%. In addition, higher morphological stability and lower energy loss were also observed in the PBDB-T-b-PYT SMOSC compared with the control PBDB-T:PYT BHJ devices. The results manifest that our newly designed PBDB-T-b-PYT provides a promising design strategy for D-A block copolymers for highly efficient and stable SMOSCs.