Inhibiting Nonradiative Recombination and Scattering Losses via Ultrafast Pulse Irradiation for Enhanced Perovskite Lasing

Lasing performance of solution-processed perovskite thin films is strictly limited by the out-of-plane scattering losses due to the wide intergrain spacings and quick nonradiative recombination at grain boundaries. Here, we show a novel strategy to regulate the morphology and properties of perovskite films with the femtosecond laser treatment, which effectively coalesces the adjacent grain boundaries and tunes the deep defect density. The experimental results along with the density functional theory calculations demonstrate that the mild residual compressive stress condition (0 MPa < sigma < -15 MPa) originating from the ultrafast nonthermal modification helps to increase the defect formation energy, thus reducing the density of deep defects, and prolongs the excited carrier lifetime for the suitable population inversion. As a result, the random lasing threshold of the perovskite thin films is dramatically reduced to a record value of 0.92 mu J/cm(2), with a 15-fold improvement in the output slope efficiency. This research will stimulate more investigations on developing high-performance perovskite light sources by the precise tuning of crystalline properties with ultrafast pulses.