Ultra-broadband near-infrared emission and enhanced thermal stability in Lu3Ga3MgSiO12:Cr3+, Yb3+ garnet phosphor via chemical unit co-substitution and energy transfer

The development of highly efficient and thermally stable phosphors with ultra-broadband emission is critical to advancing the practical applications of portable near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs). Herein, we employ the chemical unit co-substitution strategy to quantitatively introduce Mg 2+ and Si 4+ ions into the garnet lattice, yielding the high-performance Lu 3 Ga 3 MgSiO 12 :Cr 3+ (LGMSO:Cr 3+ ) phosphor, which exhibits an ultra-broadband emission with a full width at half maximum (FWHM) of 181 nm and a photoluminescence quantum yield (PLQY) of 63.7 %. Structural analysis reveals that Mg 2+ -Si 4+ co-substitution induces multiple Cr 3+ occupancy within distorted (Ga/Mg)O 6 octahedra, broadening emission band via a multisite-induced effect, as confirmed by low-temperature spectral analysis (80 K) and crystal field calculations. Furthermore, co-doping with Yb 3+ enhances the emission bandwidth and thermal stability (from 48.4 % to 71.0 % at 423 K), attributed to the combined contributions of Cr 3+ emission ( 4 T 2 ( 4 F ) → 4 A 2 ) and Yb 3+ emission ( 2 F 5 / 2 → 2 F 7 / 2 ) excited via Cr 3+ energy transfer. Packaged LED devices show superior night vision and non-destructive biological penetration capabilities, highlighting the phosphor’s potential for NIR pc-LED applications.