Thermally Evaporated MAPbBr<sub>3</sub> Perovskite Random Laser with Improved Speckle-Free Laser Imaging
Z. Zhan, Zhengzheng Liu, Juan Du, Sihao Huang, Qian Li, Zhiping Hu, Jiajun Luo, Yong Yang, Siyu Dong, Liang Wang, Jiang Tang, Yuxin Leng
Abstract
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 MAPbBr 3 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 MAPbBr 3: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.