Achieving Broadband NIR Emission in Fe³⁺-Activated ALaBBO₆ (A = Ba, Sr, Ca; B-B = Li-Te, Mg-Sb) Phosphors via Multi-Site Ionic Co-Substitutions

Phosphor-converted near-infrared (NIR) LEDs are becoming increasingly demanded as miniature, portability, and broad emission spectrum. In this work, a class of Fe3+-activated double perovskite structured is reported ALaBB ' O-6 (A = Ba, Sr, Ca; B-B ' = Li-Te, Mg-Sb) phosphors. Through the co-substitution strategy at the A-site and B-B' sites, the emission spectral intensity and position of Fe3+ ions can be tuned. Finally, by utilizing Ca2+ at the A-site and Mg-Sb co-substitution for Li-Te, long-wave NIR emission centered at 995 nm in CaLaMgSbO6: 0.6%Fe3+ with a full width at half maximum of 147 nm and internal quantum efficiency of 54.05% is achieved. The effects of the double perovskite crystal structure on Fe3+ photoluminescence properties are comprehensively analyzed. NIR LEDs are fabricated by encapsulating UV chips with the synthetic CaLaMgSbO6: 0.6%Fe3+ phosphors, and their application value in night vision, nondestructive biological monitoring, and NIR detection is evaluated.