Efficient Near‐Infrared Luminescence in Lanthanide‐Doped Vacancy‐Ordered Double Perovskite Cs2ZrCl6 Phosphors via Te4+ Sensitization

Abstract All‐inorganic lead‐free perovskite‐derivative metal halides have shown great promise in optoelectronics, however, it remains challenging to realize efficient near‐infrared (NIR) luminescence in these materials. Herein, we report a novel strategy based on Te 4+ /Ln 3+ (Ln=Er, Nd, and Yb) co‐doping to achieve efficient NIR luminescence in vacancy‐ordered double perovskite Cs 2 ZrCl 6 phosphors, which are excitable by a low‐cost near‐ultraviolet light‐emitting diode (LED) chip. Through sensitization by the spin‐orbital allowed 1 S 0 → 3 P 1 transition of Te 4+ , intense and multi‐wavelength NIR luminescence originating from the 4f→4f transitions of Er 3+ , Nd 3+ , and Yb 3+ was acquired, with a quantum yield of 6.1 % for the Er 3+ emission. These findings provide a general approach to achieve efficient NIR emission in lead‐free metal halides through ns 2 ‐metal and lanthanide ion co‐doping, thereby opening up a new avenue for exploring NIR‐emitting perovskite derivatives towards versatile applications such as NIR‐LEDs and bioimaging.