Near‐Infrared Light Emitting Metal Halides: Materials, Mechanisms, and Applications

Abstract Near‐Infrared (NIR) light emitting metal halides are emerging as a new generation of optical materials owing to their appealing features, which include low‐cost synthesis, solution processability, and adjustable optical properties. NIR‐emitting perovskite‐based light‐emitting diodes (LEDs) have reached an external quantum efficiency (EQE) of over 20% and a device stability of over 10,000 h. Such results have sparked an interest in exploring new NIR metal halide emitters. In this review, several different types of NIR‐emitting metal halides, including lead/tin bromide/iodide perovskites, lanthanide ions doped/based metal halides, double perovskites, low dimensional hybrid and Bi 3+ /Sb 3+ /Cr 3+ doped metal halides, are summarized, and their recent advancement is assessed. The characteristics and mechanisms of narrow‐band or broadband NIR luminescence in all these materials are discussed in detail. Also, the various applications of NIR‐emitting metal halides are highlighted and an outlook for the field is provided.