A novel broadband near-infrared phosphor NaBaScSi2O7: Fe3+ and its application in pc-LED and night vision

Abstract

In recent years, Fe³⁺-doped near-infrared (NIR) phosphors have garnered significant attention, primarily due to their non-toxic nature, long emission wavelength, and excellent thermal stability. In this work, a series of NaBaScSi₂O₇: xFe³⁺ (x = 0.01–0.07) phosphors were synthesized by the conventional solid-state reaction method. The impact of Fe³⁺ doping on the bandgap of NaBaScSi₂O₇ was analyzed by diffuse reflectance spectroscopy (DRS) and first-principles calculations. Under excitation at 301 nm, the series of phosphors emitted broadband NIR luminescence at 815 nm with full width at half maximum (FWHM) of 116 nm. Varying-temperature testing of the NaBaScSi₂O₇: 0.03Fe³⁺ phosphor indicated that it can retain 46% of its room temperature luminescence intensity at 423 K. This excellent thermal stability is attributed to the small Huang-Rhys factor (S), which results in weak electron-phonon coupling. In addition, the NIR phosphor-converted light-emitting diode (NIR pc-LED) integrated from the NaBaScSi₂O₇: 0.03Fe³⁺ optimal phosphor and a 310 nm ultraviolet (UV) chip showed a superior night vision capability.