Broad-Band Near-Infrared Emission with High External Quantum Efficiency from Molybdenum-Doped Vacancy-Ordered Double Perovskites for Spectroscopic Analysis

Broad-band near-infrared (NIR) luminescent materials are crucially important components of NIR light-emitting devices (LEDs) and have garnered significant attention for their wide-ranging applications in spectroscopy analysis. Here, we present vacancy-ordered double perovskite Cs2HfCl6 single crystals, which achieve efficient broad-band NIR emission through Mo4+ ion doping. The optimized sample has an internal quantum efficiency of 85.1% and an ultrahigh external quantum efficiency of 68.3%. Experimental characterizations and theoretical calculations reveal that intense NIR emission arises from dopant-induced d–d transitions. In addition, the as-synthesized NIR-emitting perovskites retain 58% of the photoluminescence intensity at 425 K compared to 300 K. The NIR LED light source fabricated by the NIR-emitting samples exhibits promising potential for application in NIR spectroscopy analysis, night vision, and nondestructive testing. This work provides insights into the electronic transitions in Mo4+-activated broad-band NIR-emitting perovskites and opens up a new horizon for designing high-performance broad-band NIR luminescence.