Regioregular and Regioirregular Poly(selenophene-perylene diimide) Acceptors for Polymer-Polymer Solar Cells

We report two new regioregular and regioirregular model copolymer acceptors based on selenophene and perylenetetracarboxylic diimide moieties, respectively, named RR-P(SePDI) and RI-P(SePDI), which were synthesized to study how regioregularity impacts the properties of resulting polymers. The structural regioregularity impact on the performance of polymer-polymer solar cells (PPSCs) was highlighted. Both the copolymer acceptors displayed similar optoelectronic properties. The regioregular RR-P(SePDI) exhibited better and balance bulk charge-transport capability than regioirregular RI-P(SePDI) in active layer films. The typical PPSCs based on the regioirregular RI-P(SePDI) copolymer acceptor and the PTB7-Th polymer donor afforded average power conversion efficiencies (PCEs) of about 5.3%. Importantly, reasonably improved average PCEs of about 6.2% were provided by the blend active layer of new regioregular RR-P(SePDI) and PTB7-Th. These results highlight the significant and efficient strategy of rational control regioregularity of the polymer backbone to gain high PCE values in perylene diimide-based PPSCs.