Highly efficient Fe 3+ -doped A 2 BB'O 6 (A = Sr 2+ , Ca 2+ ; B, B' = In 3+ , Sb 5+ , Sn 4+ ) broadband near-infrared-emitting phosphors for spectroscopic analysis.

Near-infrared (NIR)-emitting phosphor-converted light-emitting diodes have attracted widespread attention in various applications based on NIR spectroscopy. Except for typical Cr 3+ -activated NIR-emitting phosphors, next-generation Cr 3+ -free NIR-emitting phosphors with high efficiency and tunable optical properties are highly desired to enrich the types of NIR luminescent materials for different application fields. Here, we report the Fe 3+ -activated Sr 2-y Ca y (InSb) 1-z Sn 2z O 6 phosphors that exhibit unprecedented long-wavelength NIR emission. The overall emission tuning from 885 to 1005 nm with broadened full-width at half maximum from 108 to 146 nm was realized through a crystallographic site engineering strategy. The NIR emission was significantly enhanced after complete Ca 2+ incorporation owing to the substitution-induced lower symmetry of the Fe 3+ sites. The Ca 2 InSbO 6 :Fe 3+ phosphor peaking at 935 nm showed an ultra-high internal quantum efficiency of 87%. The as-synthesized emission-tunable phosphors demonstrated great potential for NIR spectroscopy detection. This work initiates the development of efficient Fe 3+ -activated broadband NIR-emitting phosphors and opens up a new avenue for designing NIR-emitting phosphor materials.