Effect of temperature on the formation of highly crystalline lead-free perovskite Cs3Sb2Br9 hexagonal microdisks

Lead-free, fully inorganic single crystal perovskite Cs3Sb2Br9 were synthesized by an inverse temperature crystallization method. The crystal structure and the morphologies of Cs3Sb2Br9 perovskite growth were controlled and optimized by varying the heating temperature. The crystallize growth of Cs3Sb2Br9 perovskite were studied at 70 degrees C, 90 degrees C, and 110 degrees C heating temperature kept in the oil bath for 2 h. We were able to investigate the effect of temperature on the perovskite crystal structure using X-ray diffraction (XRD) and Raman spectroscopy to observe the crystal interplanar distance and molecular vibrations associated with the phase transitions of the perovskite formation, as well as structural morphology of the crystal using transmission electron microscopy and Field-emission scanning electron microscopy. At a short reaction time of 2 h, XRD diffraction peaks of all samples were indexed to trigonal crystal system and correspond to the hexagonal shape with (221) and (022) plane was observed to be the preferred growth orientation for the samples. Perovskite heated at 90 degrees C have higher crystallinity phase and better hexagonal microdisks shape morphology based on the observation of an ordered internal atomic arrangement and a narrow 0.29 FWHM value width diffraction maxima. With a photoluminescence quantum yield of 23%, Cs3Sb2Br9 has great potential as emitting materials in lead-free perovskite optoelectronics.