Enhanced photoelectric performance in Cu-Bi double halide perovskite single crystals

Bi-based halide perovskites, with much lower toxicity than Pb-based perovskites, have triggered enormous interest in optoelectronic applications. However, most Bi-based perovskites have low-dimensional crystalline structures which may have potential negative effects on carrier transport. Herein, zero-dimensional (CHDA)BiI5 center dot 3H2O is transformed into two-dimensional double perovskite (CHDA)2CuBiI8 center dot 0.5H2O through Cu+ introduction engineering, which shows increased orbital overlap and improved electronic band structure dispersion compared with the former. Notably, a 104-fold enhancement in photoresponse on-off ratio is observed for the (CHDA)2CuBiI8 center dot 0.5H2O SC photodetector. This advancement not only enhances our understanding of the intricate relationship between crystal structure and charge transport behavior in Bi-based perovskites but also paves the way for highly efficient and environmentally friendly optoelectronic device development. The low-dimensional structures of Bi-based perovskites severely restrict their optoelectronic performances. Here, a Cu-Bi double perovskite single crystal exhibits enhanced optical absorption, increased carrier mobility, and inhibition of defect recombination compared to Bi-only perovskite.