Thermally Stable NIR Emission from Disordered Ba 5 La 3 MgAl 3 O 15 :Cr 3+ with Peak Wavelength Beyond 900 nm

Broadband near‐infrared (NIR) emissions in the long wavelength region with simultaneous high efficiency and thermal stability are desirable for NIR phosphor‐converted light‐emitting diodes (NIR pc‐LEDs) light sources. Herein, a novel broadband NIR‐emitting phosphor is reported, Ba 5 La 3 MgAl 3 O 15 :Cr 3+ (BLMAO:Cr 3+ ), which exhibits a NIR emission band spanning 700–1300 nm with maximum peak wavelength ( λ max ) at 925 nm and full width at half maximum of 160 nm. The optimized phosphor achieves an internal quantum efficiency of 66%, and the integrated emission intensity at 423 K remains 61% of that at room temperature, which surpasses most Cr 3+ ‐activated phosphors emitting in the long‐wavelength NIR region ( λ max > 900 nm). The NIR luminescence properties are elucidated on the basis of density functional calculations of the multiple Cr 3+ local structures as generated by the Ba/La occupation disorder in the host material. The applications of the NIR phosphor in pc‐LED devices are demonstrated, showing potential in night‐vision and nondestructive examination. The results indicate that BLMAO:Cr 3+ is a promising phosphor with highly efficient and thermally stable broadband NIR emission for NIR LED light sources.