Vapor Phase Growth of Centimeter-Sized Band Gap Engineered Cesium Lead Halide Perovskite Single-Crystal Thin Films with Color-tunable Stimulated Emission

Single crystal metal halide perovskites thin films are considered to be a promising optical, optoelectronic materials with extraordinary performance due to their low defect densities. However, it is still difficult to achieve large-scale perovskite single-crystal thin films (SCTFs) with tunable bandgap by vapor-phase deposition method. Herein, the synthesis of CsPbCl 3(1– x ) Br 3 x SCTFs with centimeter size (1 cm × 1 cm) via vapor-phase deposition is reported. The Br composition of CsPbCl 3(1– x ) Br 3 x SCTFs can be gradually tuned from x = 0 to x = 1, leading the corresponding bandgap to change from 2.29 to 2.91 eV. Additionally, an low-threshold (≈23.9 µJ cm −2 ) amplified spontaneous emission is achieved based on CsPbCl 3(1– x ) Br 3 x SCTFs at room temperature, and the wavelength is tuned from 432 to 547 nm by varying the Cl/Br ratio. Importantly, the high-quality CsPbCl 3(1– x ) Br 3 x SCTFs are ideal optical gain medium with high gain up to 1369.8 ± 101.2 cm −1 . This study not only provides a versatile method to fabricate high quality CsPbCl 3(1– x ) Br 3 x SCTFs with different Cl/Br ratio, but also paves the way for further research of color-tunable perovskite lasing.