Dual Oxidation Suppression in Lead‐Free Perovskites for Low‐Threshold and Long‐Lifespan Lasing

Abstract Low lasing threshold and long‐term operational stability are essential in advancing cost‐effective, efficient lead‐free (tin) halide perovskite lasers. However, the rapid crystallization of tin perovskites and oxidation of Sn 2+ lead to substantial amounts of lattice defects, detrimental to laser performance enhancement. Herein, a dual oxidation suppression strategy is developed to suppress the oxidation of Sn 2+ 2D tin halide perovskites, i.e., adopting an oxygen‐free two‐step growth to enhance the crystal quality and incorporating electron‐donating biuret molecules to coordinate with Sn 2+ during the crystal growth, which led to the substantial reduction of lasing threshold to <1 µJ cm − 2 in (PEA) 2 MASn 2 I 7 . This represents the lowest value in lead‐free perovskite nanolasers and approximately one order of magnitude lower than those previously reported for tin‐based nanolasers. Investigations into the spontaneous photoluminescence (PL) and stimulated lasing emission revealed that 2D tin perovskites exhibited superior photostability and lasing stability compared to their lead counterparts. Specifically, the lasing intensity of (PEA) 2 MA 2 Sn 3 I 10 constantly increased by >300% under optical pumping and the lasing threshold decreased by ≈17%, which is not observed in their lead counterparts. The findings highlight the prospect of 2D tin halide perovskites as lead‐free gain materials and cavities for solution‐processed nanolasers with low lasing thresholds and exceptional stability.