Advances in high-performance wide bandgap polymer donor materials for organic photovoltaic cells

With continuous innovation in organic photovoltaic materials, the power conversion efficiency (PCE) of organic photovoltaic (OPV) cells has approached 20%. The development of polymer donors and small molecule acceptors is considered crucial for improving the PCE of OPV cells. Among numerous donor materials, wide bandgap (WBG) polymer donors have dominated the OPV donor material field due to their excellent optoelectronic properties. To further enhance the photovoltaic efficiency of OPV, it is necessary to summarize and elucidate the correlation between the molecular structure and optoelectronic properties of WBG polymer donors. Firstly, this review summarize the methods for controlling the optical bandgap and molecular energy levels of polymer donors. Secondly, we explore and summarize the methods for controlling aggregation behavior of the polymer in solution and their correlation with their bulk heterojunction morphology. Thirdly, we emphasize the importance of reducing the energy losses in OPV cells and discuss methods to reduce these losses. Fourthly, we summarize the-state-of-the-art wide bandgap polymer donors. Finally, we discuss the opportunities and challenges for commercializing non-fullerene OPV cells based on WBG polymer donors.