Improved Amplified Spontaneous Emission in Polycrystalline Perovskite Films by the Dual‐Site Synergistic Passivation Effects of ZnS

Abstract

Halide perovskite materials are considered a promising optical gain medium for stimulated emission and have aroused tremendous interest in the field of laser research. The development of low‐threshold optically pumped amplified spontaneous emission (ASE) is critical for the advancement of continuous wave (CW) and electrically pumped micro‐nano lasers. In this work, an efficient ZnS additive is incorporated into the FA0.85MA0.15PbI2.55Br0.45 perovskite films to diminish the ASE threshold and extend the photostability by the dual‐site synergistic passivation. The experimental measurements and first‐principles calculations based on the density functional theory (DFT) are employed to elucidate the doping mechanism. The designed ZnS‐based perovskite films yield a mitigated ASE threshold of 8.5 µJ cm−2 with an elevated optical gain coefficient of 109.06 cm−1, which outperform those of the control films (12.7 µJ cm−2 and 74.10 cm−1). The in‐depth experimental characterizations and theoretical calculations have corroborated that the improvement of ASE performance can be ascribed to the dual‐site synergistic passivation effects of Zn2+ and S2−, which reduces the surface defects of perovskite films, suppresses the nonradiative charge recombination and improves the optical stability. This work provides a resultful strategy to construct the solution‐processed perovskite lasers with low thresholds and superior stability.