Espalhamento Raman e fotoluminescência a baixas temperaturas da perovskita CsPbBr3

Abstract

Halide perovskites represent a class of semiconductor materials characterized by a perovskite like crystal structure, in which metal ions are coordinated to halide ions. These materials have attracted significant attention due to their exceptional electronic and optical properties, such as high light absorption, high charge carrier mobility, and other properties, making them promising for energy-related applications, including solar cells, LEDs, and photodetectors. Among them, CsPbBr3 stands out for its potential in optoelectronic devices. In this work, CsPbBr3 crystals were synthesized in the laboratory by dissolving CsBr and PbBr in hydrobromic acid, with structural quality confirmed by X-ray diffraction. Raman spectroscopy and photoluminescence (PL) analyses were performed to investigate their vibrational and electronic properties. Raman spectra revealed vibrational modes consistent with existing literature. No phase transitions were observed within the measured temperature range. Room-temperature PL measurements exhibited two emission bands attributed to structural defects and free excitons, which are excitons that can move freely through the crystal without being trapped by impurities or structural defects.Upon cooling to 93 K, an additional band emerged, corresponding to bound excitons, which are linked to impurities or defects in the crystal structure. These results provide valuable insights into the structural and optical behavior of CsPbBr3, further advancing its application potential in optoelectronics.