Random Lasing from Thermally Evaporated Quasi-Two-Dimensional Perovskite Film for Speckle-free Imaging

Quasi-two-dimensional (quasi-2D) perovskites are promising as a gain medium for laser applications owing to their inherent multiple quantum wells and remarkable stability. Meanwhile, thermal evaporation deposition is a promising complementary approach to further advance the commercialization of perovskite-based lasers. However, investigations into thermally evaporated perovskite lasers are scarce, and their performance is significantly inferior to that of their solution-processed counterparts. Herein, we demonstrate a high-quality thermally evaporated quasi-2D perovskite film with excellent gain properties via a tri-source co-evaporation strategy. The carrier dynamics and gain nature of the perovskite film are revealed with a long gain lifetime of 66.5 ps. The net modal gain is up to 1071 cm–1, which is afforded by rapid carrier accumulation (<0.25 ps) and facile buildup of population inversion. As a result, random lasing from the quasi-2D perovskite film with a low threshold of 10.39 μJ/cm2 is achieved. Furthermore, under the illumination of random lasing, clear speckle-free imaging with an impressively low speckle contrast of C ∼ 0 is demonstrated. This work highlights the possibility of using thermally evaporated perovskites for the development of high-performance random lasers and integrated speckle-free imaging systems.