A medium-bandgap small molecule donor compatible with both fullerene and unfused-ring nonfullerene acceptors for efficient organic solar cells

Here we designed and synthesized a new small molecule donor DRC4TB with an alkylthiothienyl-substituted benzodithiophene as the core and 3-butyl rhodanine as the terminal group, which showed an optical bandgap of 1.87 eV. DRC4TB was compatible with both a fullerene acceptor (PC71BM) and an unfused-ring nonfullerene acceptor (HF-PCIC). The optimized DRC4TB:PC71BM and DRC4TB:HF-PCIC solar cells delivered comparable power conversion efficiencies (PCEs) of 8.53% and 8.68%, respectively.