Optimizing Lasing Performance of CsPbBr₃ Microplates by Regulating Exciton Recombination Dynamics with Pressure

This study aims to achieve an ultralow lasing threshold in CsPbBr₃ microplates (MPs), a crucial step toward developing electrically driven micro/nanolasers for optics integrated chips. We investigate the lasing behavior of CsPbBr₃ MPs under varying pressures by using static-state photoluminescence (PL), time-resolved PL (TRPL), and first-principles theory calculations based on density functional theory (DFT). Our results reveal that the lasing threshold initially decreases and then increases, with a critical turning point at 0.44 GPa. Notably, we achieve an optimal lasing threshold of 20.87 μJ/cm² after releasing pressure from 1.87 GPa, highlighting the potential of pressure modulation to optimize the lasing performance. At low pressure, pressure-induced phonon hardening enhances the barrier, preventing excitons decay from free states to trapping states. Conversely, at higher pressure, the increased density of surface defects, due to pressure-induced anisotropic contraction of lattice constants along the c-axis, leads to excitons decay from free states to trapping states. For CsPbBr₃ MPs, it is evident that only free excitons contribute to lasing, while both free and trapped excitons contribute to luminescence. These findings offer a novel strategy to optimize the lasing performance of perovskite micro/nanolasers, significantly advancing their potential for practical applications in optoelectronic devices.