Near‐Infrared Emission of Sm²⁺ in Oxynitrides

Abstract Near‐infrared (NIR) luminescent materials hold promising applications in NIR spectroscopy technologies, but the NIR emitters are largely limited to some transition metals with spin‐forbidden transitions that lead to low absorption efficiency of the pumping light. Exploring novel efficient NIR emitters is thus an urgent and challenging task for developing high‐efficiency NIR luminescent materials. Here, an interesting NIR emission of Sm²⁺ is reported in BaAlSi₅O₂N₇, which exhibits both a line spectrum at 682 nm and a broadband centered at 778 nm with a full‐width at half maximum (FWHM) of 141 nm. Temperature‐dependent photoluminescence spectra and decay curves evidence that the thermally assisted electrons crossover (TAEC) process contributes to the enhancement of the broadband NIR emission. The fabricated NIR phosphor‐converted light‐emitting diode (pc‐LED) shows promising potential as a NIR lighting source and proves robust thermal stability under high‐temperature aging test. The present surprising NIR emission from Sm²⁺ in highly stable oxynitrides opens a way to explore efficient and reliable NIR phosphors that are suitable for commercial LED chips.