• donor-acceptor polymers;
  • imide-based polymers;
  • organic photovoltaic cells;
  • morphology;
  • metal oxides
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Bithiophene imide (BTI) and benzodithiophene (BDT) copolymers are synthesized for application in organic photovoltaic (OPV) cells. The electron deficiency of the BTI units leads to polymers with a low-lying HOMOs (∼-5.6 eV). Inverted solar cells are fabricated to investigate the OPV performance of the BTI-based polymers and achieve power conversion efficiencies up to 5.5%, with substantial Vocs above 0.9 V which are among the highest Vocs reported to date for polymer/PCBM solar cells. The results indicate that the BTI is a promising building block for constructing polymer donors for OPV applications.