Unraveling Stimulated Emission by Pump–Probe Spectroscopy in Space-Confined Inorganic and Hybrid Perovskite Crystals

High Resolution Image Download MS PowerPoint Slide Halide perovskites play a central role in next-generation photonic devices. Due to their tunable optical band gap, along with exceptionally high luminescence quantum yield and defect tolerance, halide perovskites are excellent candidates for lasing applications. By combining photoluminescence and stimulated emission with pump–probe spectroscopy from the same region of the sample, this work provides insights into the nature of excited states responsible for lasing in cesium lead bromide (CsPbBr 3 ) and methylammonium lead bromide (MAPbBr 3 ) crystals. The broadening and the rate of change in intensity of the ground state bleach peak allow for an estimation of the threshold carrier densities and stimulated emission lifetimes. Space-confined solution crystallization, which yields uniform perovskite crystals, was used for the growth of CsPbBr 3 and MAPbBr 3 crystals. The lasing threshold for both systems is found to be around 35 μJ/cm 2 . The overall transient absorption (TA) features from CsPbBr 3 and MAPbBr 3 crystals are similar. A detailed analysis of the TA spectra is presented from a thin MAPbBr 3 and a CsPbBr 3 crystal, where a large range of pump fluence was used from below to well above the lasing thresholds. A deconvolution decay model is developed to extract features of the stimulated emission from the ground state bleaching and photoinduced absorption.