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

This study aims to achieve an ultralow lasing threshold in CsPbBr microplates (MPs), a crucial step toward developing electrically driven micro/nanolasers for optics integrated chips. We investigate the lasing behavior of CsPbBr 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/cm 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 -axis, leads to excitons decay from free states to trapping states. For CsPbBr 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.