Anti-Thermal Quenching and Tunable Near-Infrared Luminescence in High-Efficiency Garnet SrLu2Al3ScSiO12: Cr3+, Yb3+ Phosphors for Multifunctional Applications

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have found extensive applications in diverse fields including night vision, medical diagnostics, and plant lighting. However, designing NIR phosphors with large full width at half maximum (FWHM) and high thermal stability remains challenging. In this study, we developed a SrLu₂Al₃ScSiO₁₂: Cr³⁺, Yb³⁺ phosphor (abbreviated as SLASSO: Cr³⁺, Yb³⁺) through a high-temperature solid-state reaction method. The SLASSO: Cr³⁺ samples exhibit two broad absorption bands in the blue light region (~440 nm) and red light region (~600 nm), confirming their can effective excitation by blue LED chips. Through precise control of the crystal field environment surrounding Cr³⁺ ions, the emission spectra of SLASSO: xCr³⁺ phosphors demonstrate tunability from narrow-band to broadband emission, with emission peaks adjustable from 705 nm to 807 nm and FWHM expandable from 88 nm to 185 nm. SLASSO: 2%Cr³⁺ phosphor demonstrates high quantum efficiency (75%) and excellent thermal stability (95%@423 K). By designing the energy transfer between Cr³⁺ and Yb³⁺, SLASSO: 2%Cr³⁺, 1%Yb³⁺ phosphors achieved both enhanced luminescence above 1000 nm and zero thermal quenching (103%@423 K). A prototype NIR pc-LED device demonstrated remarkable performance, achieving an output power of 59.68 mW at 300 mA and a high photoelectric conversion efficiency of 30.76% under 10 mA. These results highlight the SrLu₂Al₃ScSiO₁₂: Cr³⁺, Yb³⁺ phosphor's potential for diverse applications, including non-destructive testing, medical diagnostics, anti-counterfeiting, and night vision technologies.