Benzodithiophene Hole-Transporting Materials for Efficient Tin-Based Perovskite Solar Cells

Developing efficient interfacial hole transporting materials (HTMs) is crucial for achieving high-performance Pb-free Sn-based halide perovskite solar cells (PSCs). Here, a new series of benzodithiophene (BDT)-based organic small molecules containing tetra- and di-triphenyl amine donors prepared via a straightforward and scalable synthetic route is reported. The thermal, optical, and electrochemical properties of two BDT-based molecules are shown to be structurally and energetically suitable to serve as HTMs for Sn-based PSCs. It is reported here that ethylenediammonium/formamidinium tin iodide solar cells using BDT-based HTMs deliver a champion power conversion efficiency up to 7.59%, outperforming analogous reference solar cells using traditional and expensive HTMs. Thus, these BDT-based molecules are promising candidates as HTMs for the fabrication of high-performance Sn-based PSCs.