Engineering Broadband Emission of Zn₂Ga_0.5-yAl_ySb_0.5O₄∶Cr³⁺ Phosphors for Near-Infrared LED Application

In phosphor-converted light-emitting diode (pc-LED)-based near-infrared light sources for biochemical analysis and medical diagnostics, phosphors with broadband near-infrared (NIR) emission play an important role, and obtaining such phosphors is a great challenge. Herein, efficient broadband NIR-emitting Zn₂Ga_0.5-yAl_ySb_0.5O₄:Cr³⁺ phosphors are developed by introducing Al³⁺ to gradually replace Ga³⁺ in the host Zn₂Ga_0.5Sb_0.5O₄ through crystal engineering. Spectral analysis and densitometric calculations show that this homogeneous cation substitution strategy optimizes the local lattice environment and significantly suppresses the nonradiative relaxation of the Cr³⁺ emission centers, thus exhibiting strong broadband NIR emission properties. In addition, Cr³⁺ ions show varied low-temperature emissions with notable temperature sensitivity differences among centers. At 90 K, the material achieves a maximum relative sensitivity of 1.45% K^-1, highlighting its potential as a thermosensitive material for low-temperature applications and temperature sensing. The NIR LED light source fabricated based on this material shows a significant response to different liquids in transmission spectral analysis, suggesting its potential for important applications in the identification of organic compounds.