Roles of shallow energy level defect states on amplified spontaneous emission enhancement of CH₃NH₃PbBr₃ perovskite crystals

Abstract In this work, we demonstrated the role of shallow energy level defect states on the emission of CH 3 NH 3 PbBr 3 perovskite polycrystals under laser excitation. The perovskite polycrystals were synthesized by a simple, one-step, low-cost solution self-assembled method. By adjusting the sample preparation temperature from 303 to 373 K, we could manipulate the number of shallow energy level defect states, which were evaluated through low-temperature photoluminescence measurement. This led to an evolution of the CH 3 NH 3 PbBr 3 perovskite polycrystals’ emission from amplified spontaneous emission to random lasing emission. As a result, the most efficient lasing threshold of 4 μ J mm −2 was achieved with the CH 3 NH 3 PbBr 3 perovskite polycrystals synthesized at the optimum temperature of 333 K. Furthermore, the surface morphologies and the crystal structure of the CH 3 NH 3 PbBr 3 perovskite polycrystals were also taken into consideration to unravel the role of defects in the CH 3 NH 3 PbBr 3 perovskite polycrystals.