Double-Site Occupation Triggered Broadband and Tunable NIR-I and NIR-II Luminescence in AlNbO4:Cr3+ Phosphors

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) are desired for optoelectronic and biomedical applications, while the development of target broadband NIR phosphors still remains a significant challenge. Herein, a kind of Cr 3+ -doped AlNbO 4 phosphors with a broad NIR emission ranging from 650 to 1400 nm under 450 nm excitation are reported. A giant red-shift emission peak from 866 to 1020 nm together with broadened full width at half-maximum of 320 nm is achieved simply by varying the doped Cr 3+ concentrations. Structural and spectroscopy analysis demonstrate that a concentration-dependent site-occupation of Cr 3+ emitters in different Al 3+ sites is responsible for the tunable NIR luminescence. The as-fabricated NIR pc-LED based on optimized AlNbO 4 :Cr 3+ phosphor exhibits great potential in night-vision applications. This work provides a novel design principle on the Cr 3+ -doped AlNbO 4 phosphor with tunable broadband luminescence from NIR-I to NIR-II, and these materials can be employed in NIR spectroscopy applications.