Thermally Stable NIR Emission from Disordered Ba5La3MgAl3O15:Cr3+ 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.