Systematic Studies on CsSnBr₃ Perovskite Microcrystals: CVD Growth, Structure, Stability and Optical Properties

Although lead-based halide perovskites have promising applications in optoelectronic devices, these applications are limited by the toxicity of the materials. Therefore, it is necessary to develop lead-free all-inorganic substitute such as tin-based halide perovskites in spite of the enormous challenges in their controllable synthesis and stability. Here, we report the controlled growth of high quality CsSnBr₃ microcrystals on SiO₂/Si substrates by chemical vapor deposition method. The as-prepared products predominantly show the morphology of triangle star and nail-like rod and the structure of cubic phase. The control of nucleation density and size of CsSnBr₃ microcrystals has been realized by varying the growth temperature. The results of air-exposed samples provide direct evidences for explaining the structural instability of the tin-based perovskites, which is attributed to the production of SnO. The power and temperature dependent photoluminescence spectra reveal that CsSnBr₃ microcrystals with different morphologies possess different exciton binding energies and produce different photoexcitation species due to the quantum confinement effect that changes the electron-hole effect.