Enhanced luminescence performance of near-infrared phosphor Y2CaAl4SiO12: Fe3+, Yb3+ through energy transfer for anti-counterfeiting applications

Environment-friendly Fe 3+ ions as near-infrared (NIR) activators have garnered significant attention in intelligent NIR light sources; however, designing wavelength-tunable and outstanding thermal stability Fe 3+ -doped NIR luminescent materials remains a formidable challenge. In this study, we synthesized a novel garnet-structured NIR phosphor Y 2 CaAl 4 SiO 12 : Fe 3+ , Yb 3+ and investigated its luminescent properties and energy transfer mechanisms. Under 270 nm ultraviolet light excitation, Y 2 CaAl 4 SiO 12 : Fe 3+ demonstrates broadband NIR emission peaking at 803 nm, characterized by a full width at half maximum (FWHM) of 107 nm and exhibiting a remarkably high internal quantum efficiency (IQE) of 91.70 %, which is markedly superior to most reported Fe 3+ doping NIR-emitting materials. Notably, the incorporation of Yb 3+ ions facilitates an efficient energy transfer process from Fe 3+ to Yb 3+ , which not only significantly broadens the emission spectrum but also enhances the thermal stability of Fe 3+ (I 373 K /I 298 K  = 59.24 %) compared to the singly Fe 3+ doped sample (I 373 K /I 298 K  = 45.30 %). Finally, the optimized Y 2 CaAl 4 SiO 12 : Fe 3+ , Yb 3+ NIR phosphor exhibits promising potential for anti-counterfeiting applications.