Thermally Evaporated MAPbBr3 Perovskite Random Laser with Improved Speckle-Free Laser Imaging

Metal halide perovskites (MHPs) are very promising materials for lasing applications due to their remarkable optical gain properties. Currently, most perovskite-based lasers are fabricated using lab-scale solution processing methods. The thermal evaporation (TE) method could be a promising alternative technology for scale-up fabrication with significantly improved reproducibility. Unfortunately, the fast and uncontrollable crystal growth process in thermal evaporation leads to defective films, and hence their laser performance usually falls behind their solution-processed counterparts. Here, we demonstrate high-performance random lasers and explore their speckle-free imaging application from perovskite thin films fabricated by an improved tri-source thermal co-evaporation approach assisted by a multifunctional Lewis base additive, triphenylphosphine oxide (TPPO). The optical gain of TPPO-passivated MAPbBr3 perovskite films is as high as ∼5 times that of the pristine one, and the corresponding gain lifetime is almost doubled after TPPO passivation. Due to the small grain size and compact confinement-induced strong multiple scattering, a random laser with threshold reduced by half and a high polarization degree of 78.4% is realized in thermally evaporated MAPbBr3:TPPO perovskite films. These findings would provide a possible route to scale up the manufacturing of high-performance perovskite materials and devices and open new perspectives for integrated speckle-free laser imaging systems.