Exciton recombination mechanisms in solution grown single crystalline CsPbBr3 perovskite

Lead halide perovskites have attracted tremendous attention recently due to their great success in the fields of photovoltaic technologies and light-emitting devices. In this work, the excitonic photoluminescence (PL) properties of all-inorganic perovskite CsPbBr3 were investigated in detail via temperature-dependent PL and Raman spectroscopy in the range of 87 K–297 K, benefiting from our recent work on solution growth of high-quality CsPbBr3 single crystals. The exciton binding energy was extracted as 37 ± 2.7 meV from temperature-dependent PL emission intensity. Furthermore, the PL emission peak energy showed complicated behaviors compared to common semiconductors. With the increase of temperature, the PL emission spectrum blueshifted below 223 K, while it was redshifted in the range of 223 K–293 K. Theoretical research indicated that the thermal expansion governs the energy bandgap evolution of CsPbBr3 below 223 K, while for higher temperatures, the contribution of electron-phonon interaction became dominant. Meanwhile, the broadening of the PL emission spectrum was mainly attributed to the exciton-longitudinal optical phonon scattering. Our results may contribute to a better understanding of the luminescence behaviors in all-inorganic perovskite CsPbBr3-based light-emitting devices in the future. •High-quality CsPbBr3 are grown using low-temperature oil bath evaporation method.•Thermal expansion governs the energy bandgap evolution below 223 K.•Electron-phonon interactions become dominant at high temperatures.•The PL spectra broadening is attributed to the exciton-LO phonon scattering.