Tailoring Fe3+‐Activated Broadband NIR Phosphors: Enhancing External Quantum Efficiency and Spectrum Adjustability Through Crystal Field Engineering in Double Perovskite Antimonate Structures

Abstract For near‐infrared (NIR) luminescent materials, it is a challenge to develop the next generation materials with high external quantum efficiency (EQE), low toxicity, and adjustable spectrum. The transition metal ion Fe 3+ can act as a good activator and emit NIR light in oxide host lattice, but there is limited research on this topic. Herein, authors have developed a series of Fe 3+ activated A 2 BSbO 6 :yFe 3+ (A = Ca, Sr, Ba; B = Sc, Y, Ga) phosphors with a double perovskite structure, which can efficiently convert the exciting light into NIR emission in the range of 750–1200 nm with a full‐width half‐maximum (FWHM) of 1372−1525 cm −1 . The NIR luminescence originates from the 4 T 1 (4G)→ 6 A 1 (6S) transition of the Fe 3+ ions situated in the octahedral sites. By employing crystal field engineering, the emission spectra peak can be adjusted within the range of 842–944 nm, and the excitation spectra can be tuned from 334 to 374 nm. These spectral adjustments enable a good match between the phosphors and commercially ultraviolet chips. When excited at 334 nm, the Sr 2 ScSbO 6 :0.1%Fe 3+ phosphor demonstrates a remarkably high EQE of 54.2% and high luminescent thermostability. These characteristics make it suitable for applications in NIR spectral detection.