Anion‐Position‐Driven Photoluminescence Enhancement Enables Low‐Threshold Lasing in CsPbCl _x Br _3‐x Microwires

ABSTRACT Cesium lead halide perovskites (CsPbX 3 ) have emerged as promising materials for optoelectronic applications due to their excellent solution processability, tunable broadband bandgap, and superior charge carrier transport properties. However, bandgap tunability is typically achieved through halide ion exchange, which often introduces defects, leading to decreased luminescence efficiency and limiting practical applications. Here, we demonstrate anion‐position‐driven lattice reconfiguration strategy as a simple yet effective strategy to optimize the optical properties of perovskite alloy microwires. The PL intensity increases by 2–3 orders of magnitude, demonstrating exceptional stimulated emission characteristics. Theoretical simulations, supported by temperature‐dependent photoluminescence (PL) spectroscopy, reveal that halide ion migration during annealing facilitates defect passivation, significantly enhancing radiative recombination efficiency. Additionally, the lasing threshold of the annealed alloy microwires decreases dramatically from an initial 62.82 to 11.8 µJ/cm 2 , representing an over 80% reduction. This study highlights the critical role of high‐temperature annealing in optimizing the optoelectronic properties of perovskites and underscores its potential for enabling low‐threshold, high‐efficiency perovskite micro‐lasers for next‐generation photonic devices.