Perovskite_Supporting Information_data

In this work, we demonstrated the role of shallow energy level defect states on the emission of CH₃NH₃PbBr₃ 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, we could manipulate the shallow energy level defect states that can be recognized through low-temperature photoluminescence measurement. Depending on the shallow energy level defect states, the sample’s emission experienced an evolution from amplified spontaneous emission to random lasing emission. Notably, the most efficient lasing threshold of 4 μJ/mm² was achieved when the sample was prepared at 333 K. The surface morphologies and other optical properties of the perovskite polycrystals were also investigated by optical microscopy, X-ray diffractometer.