Crystalline all-inorganic lead-free Cs₃Sb₂I₉ perovskite microplates with ultra-fast photoconductive response and robust thermal stability

Hybrid organolead halide perovskites have attracted tremendous attention due to their recent success as high efficiency solar cell materials and their fascinating material properties uniquely suitable for optoelectronic devices. However, the poor ambient and operational stability as well as the concern of lead toxicity greatly hamper their practical utilization. In this work, crystalline, all-inorganic and lead-free Cs₃Sb₂I₉ perovskite microplates are successfully synthesized by a two-step chemical vapor deposition method. As compared with other typical lead-free perovskite materials, the Cs₃Sb₂I₉ microplates demonstrate excellent optoelectronic properties, including substantial enhancements in the Stokes shift, exciton binding energy and electron-phonon coupling. Simple photoconductive devices fabricated using these microplates exhibit an ultra-fast response with the rise and decay time constants down to 96 and 58 µs, respectively. This respectable photoconductor performance can be regarded as a record among all the lead-free perovskite materials. Importantly, these photodetectors show superior thermal stability in a wide temperature range, capable to function reversibly between 80 and 380 K, indicating their robustness to operate under both low and high temperatures. All these results evidently suggest the technological potential of inorganic lead-free Cs₃Sb₂I₉ perovskite microplates for next-generation high-performance optoelectronic devices.