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

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 Te⁴⁺ /Ln³⁺ (Ln=Er, Nd, and Yb) co-doping to achieve efficient NIR luminescence in vacancy-ordered double perovskite Cs₂ ZrCl₆ phosphors, which are excitable by a low-cost near-ultraviolet light-emitting diode (LED) chip. Through sensitization by the spin-orbital allowed ¹ S₀ →³ P₁ transition of Te⁴⁺ , intense and multi-wavelength NIR luminescence originating from the 4f→4f transitions of Er³⁺ , Nd³⁺ , and Yb³⁺ was acquired, with a quantum yield of 6.1 % for the Er³⁺ emission. These findings provide a general approach to achieve efficient NIR emission in lead-free metal halides through ns² -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.