Enhancing Amplified Spontaneous Emission in Perovskite Thin Films by Thickness Regulation: Insights into Carrier Distribution and Optical Confinement

Abstract Metal halide perovskites have emerged as compelling contenders for cost‐effective semiconductor lasers, with advancements driven by the refinement of the gain medium, resonant cavities, and device architectures. Elucidating the underlying mechanisms, often through amplified spontaneous emission (ASE), is crucial for optimizing the photophysical properties of these gain materials. This research delves into two critical yet commonly overlooked factors—film thickness and excitation wavelength—that significantly influence ASE performance. By adjusting these variations, the ASE threshold is notably reduced from 49.26 ± 0.05 µJ cm 2 (200 nm film under 650 nm excitation) to 5.84 ± 0.05 µJ cm 2 (60 nm film under 400 nm excitation). This findings demonstrate that the ASE threshold experiences an initial decline followed by an increase with reduced thickness, with optimal thicknesses differing for various excitation wavelengths due to the interplay of optical confinement and non‐uniform carrier distribution. This study provides valuable insights beyond material composition, dimensions, and morphology, offering a fresh perspective for the advancement of electrically pumped perovskite lasers.