Large-Scale Thin CsPbBr₃ Single-Crystal Film Grown on Sapphire via Chemical Vapor Deposition: Toward Laser Array...

Single-crystal perovskites with excellent photophysical properties are considered to be ideal materials for optoelectronic devices, such as lasers, light-emitting diodes and photodetectors. However, the growth of large-scale perovskite single-crystal films (SCFs) with high optical gain by vapor-phase epitaxy remains challenging. Herein, we demonstrated a facile method to fabricate large-scale thin CsPbBr₃ SCFs (∼300 nm) on the c-plane sapphire substrate. High temperature is found to be the key parameter to control low reactant concentration and sufficient surface diffusion length for the growth of continuous CsPbBr₃ SCFs. Through the comprehensive study of the carrier dynamics, we clarify that the trapped-related exciton recombination has the main effect under low carrier density, while the recombination of excitons and free carriers coexist until free carriers plays the dominate role with increasing carrier density. Furthermore, an extremely low-threshold (∼8 μJ cm^-2) amplified spontaneous emission was achieved at room temperature due to the high optical gain up to 1255 cm^-1 at a pump power of 20 times threshold (∼20 P_th). A microdisk array was prepared using a focused ion beam etching method, and a single-mode laser was achieved on a 3 μm diameter disk with the threshold of 1.6 μJ cm^-2. Our experimental results not only present a versatile method to fabricate large-scale SCFs of CsPbBr₃ but also supply an arena to boost the optoelectronic applications of CsPbBr₃ with high performance.