Facile synthesis and characterization of CsPbBr$_3$ and CsPb$_2$Br$_5$ powders

摘要

All-inorganic caesium lead-halide perovskite CsPbBr$_3$ and CsPb$_2$Br$_5$ powders have emerged as attractive optoelectronic materials owing to their stabilities and highly efficient photoluminescence (PL). Herein we report a facile chemical route to prepare highly luminescent monoclinic CsPbBr$_3$ and tetragonal CsPb$_2$Br$_5$ powders at room temperature.The CsPbBr$_3$ powders exhibit regular crystal shape and demonstrate polyhedral geometry with an average particle size of 10 $mu$m. The CsPb2Br$_5$ powders show platelet morphologies and the lateral sizes of the particles are from 5 up to 200 $mu$m. Both CsPbBr$_3$ and CsPb$_2$Br$_5$ powders present a narrow emission line-width and PL emission of 528 and 527 nm, respectively. A direct band gap of 2.35 eV and an indirect band gap of 3.01 eV are calculated for CsPbBr$_3$ and CsPb$_2$Br$_5$ powders, respectively. In addition, the monoclinic CsPbBr$_3$ can be transformed to tetragonal CsPb$_2$Br$_5$ in the presence of water. The large-scale synthesis of CsPbBr$_3$ and CsPb$_2$Br$_5$ will be advantageous in future applications of optoelectronic devices.