Deep‐Blue Perovskite Single‐Mode Lasing through Efficient Vapor‐Assisted Chlorination

Abstract

Abstract Metal halide perovskites have emerged as promising candidates for solution‐processed laser gain materials, with impressive performance in the green and red spectral regions. Despite exciting progress, deep‐blue—an important wavelength for laser applications—remains underexplored; indeed, cavity integration and single‐mode lasing from large‐bandgap perovskites have yet to be achieved. Here, a vapor‐assisted chlorination strategy that enables synthesis of low‐dimensional CsPbCl 3 thin films exhibiting deep‐blue emission is reported. Using this approach, high‐quality perovskite thin films having a low surface roughness (RMS ≈ 1.3 nm) and efficient charge transfer properties are achieved. These enable us to document low‐threshold amplified spontaneous emission. Levering the high quality of the gain medium, vertical‐cavity surface‐emitting lasers with a low lasing threshold of 6.5 µJ cm −2 are fabricated. This report of deep‐blue perovskite single‐mode lasing showcases the prospect of increasing the range of deep‐blue laser sources.