High performance ultraviolet photodetector based on lead-free bismuth perovskite heterojunction

Metal-based halide perovskite materials are very promising for high-performance optoelectronic devices due to their extraordinary photoelectric properties. Bismuth-based perovskites are believed to replace the toxic Pb-based perovskites in optoelectronics due to their remarkable stability, and nontoxic properties. Here, we report self-powered Cs₃Bi₂Br₉/SnO₂ heterojunction ultraviolet (UV) photodetectors with excellent photoelectric detectivity. The optimized device exhibits an excellent ON/OFF ratio of 5.5 \(\times\) $\times$ 10³, a large responsivity of 25 mA/W, and a detectivity of 6.9 \(\times\) $\times$ 10¹¹ Jones at 0 V bias, which is much better than other bismuth halide perovskites with the same structure. In addition, our photodetector performance of the optimized device exhibits almost no change even after 30 days of exposure under an ambient environment, indicating excellent stability. Sulphur is introduced to Cs₃Bi₂Br₉ via bismuth ethyl-xanthogenate (Bi(Xt)₃) to further improve the device performance. Detectivity of 9.2 × 10¹¹ Jones and responsivity of 37 mAW^–1 are achieved, which shows the best performance for bismuth-perovskite photodetector in this work. This work provides a method for fabricating high-performance and stable bismuth-based perovskite photodetectors with perovskite/inorganic heterojunctions.