Spectral properties of cesium lead iodide perovskite nanocrystals in borogermanate glass at different temperatures

The aim of this work is to investigate temperature effect on spectral properties CsPbI3 perovskite nanocrystals nucleated in borogermanate glass by isothermal heat treatment at different temperatures. The temperature dependence of the first exciton absorption intensity in the heating-cooling cycle has a form of hysteresis loop, which helps determine crystallization and melting temperatures. Considering anomalies on heat curves, a phase transition from a non-perovskite to a cubic crystal structure is found in the range of 420-460 degrees C. The increase of initial nucleation temperature from 470 to 550 degrees C results in a change of phase transitions temperatures: melting, crystallization, and transition from a non-perovskite to a cubic crystal structure increase in the regions 454-475, 281-301 and 421-459 degrees C respectively due to quantum-sized effect. Results demonstrate that the cesium lead halide perovskite properties can be stabilized up to 440 degrees C, which greatly exceeds the chemical resistance of perovskites in organic matrix.