Green Fe³⁺-activated near-infrared phosphor: energy transfer-driven luminescence enhancement and multifunctional...

Near-infrared (NIR) phosphor-converted light-emitting diodes have been widely applied in biomedical imaging, night-vision security surveillance, and nondestructive inspection. Owing to its natural abundance, low cost, and environmental benignity, Fe³⁺ is regarded as a promising activator for the development of broadband NIR phosphors. However, related studies remain relatively limited. In this study, an Fe³⁺-activated Sr₂Sc₂B₄O₁₁ phosphor is successfully synthesized. Under excitation at 353 nm, the phosphor exhibits broadband NIR emission covering the range of 800-1400 nm, with an emission peak centered at approximately 956 nm, a full width at half maximum (FWHM) of 183 nm, and an internal quantum efficiency of 34%. Furthermore, Yb³⁺ co-doping is introduced to construct an energy transfer system to enhance the optical performance. The energy transfer interaction between Yb³⁺ and Fe³⁺ not only significantly improves the thermal stability but also increases the internal quantum efficiency to 75.5%. In addition, NIR pc-LED devices fabricated using the Sr₂Sc₂B₄O₁₁: Fe³⁺ phosphor demonstrate promising application potential in venous imaging, night-vision security surveillance, information encryption, and nondestructive inspection.