Sb3+‐Doping in Cesium Zinc Halides Single Crystals Enabling High‐Efficiency Near‐Infrared Emission

Abstract Luminescent metal halide materials with flexible crystallography/electronic structures and tunable emission have demonstrated broad application prospects in the visible light region. However, designing near‐infrared (NIR) light‐emitting metal halides remains a challenge. Here, an enlightening prototype is proposed to explore the high‐efficiency broadband NIR emission in metal halide systems by incorporating Sb 3+ into the Cs 2 ZnCl 4 matrix. Combined experimental analysis and density functional theory calculations reveal a modified self‐trapped excitons model to elaborate the NIR emission. The high photoluminescence quantum yield of 69.9% peaking at 745 nm and large full width at half maximum of 175 nm, along with excellent air/thermal stability, show the unique advantages of lead‐free metal halide Cs 2 ZnCl 4 :Sb 3+ as the NIR light source. The substitution of Cl − by Br − further enables the red‐shift of emission peak from 745 to 823 nm. The NIR light‐emitting diode device based on Cs 2 ZnCl 4 :Sb 3+ demonstrates potential as a non‐visible light source in night vision. This study puts forward an effective strategy to design the novel eco‐friendly and high‐efficiency NIR emissive materials and provides guidance for expanding the application scope of luminescent metal halides.