Low‐threshold FAPbBr ₃ lasers based on a dual‐additive strategy

Abstract Achieving low‐threshold lasing in formamidinium (FA)‐based perovskite films remains challenging due to difficulties in controlling their crystallization. In this study, we introduce a dual‐additive strategy utilizing zinc acetate (Zn(Ac) 2 ) and 5‐aminovaleric acid (5‐AVA) to modulate the crystallization process of FA‐based perovskite films. The synergistic effect of these additives enables the formation of smooth and dense FAPbBr 3 films with a low surface roughness of 1.36 nm and a high photoluminescence quantum efficiency (PLQE) of 63.6%. Based on these high‐quality films, we demonstrate amplified spontaneous emission with a threshold as low as 26 μJ/cm 2 . Moreover, by integrating the perovskite films with distributed feedback gratings, we achieve perovskite lasing with a record‐low threshold of 15.5 μJ/cm 2 under nanosecond‐pulsed optical excitation at room temperature. This work offers valuable insights into the fabrication of high‐quality FA‐based perovskite films and represents a significant step toward the development of high‐performance perovskite laser devices.