Achieving High-Performance Near-Infrared Cr3+-Activated Phosphor via A&C Lattice Sites Cosubstitution Strategy in Garnet for Plant Lighting
Near-infrared (NIR) spectroscopy has significantly advanced NIR light sources, yet creating NIR emitters with optimal luminescence properties, high thermal stability, and adjustable emission peaks remains a critical challenge for future smart NIR devices. Here, we introduce a chemical unit cosubstitution strategy by incorporating Ca2+ and Sn4+ ions into the garnet structure. Through this approach, Y3−yCayGa4.95−ySnyO12:0.05Cr3+ (y = 0–1) phosphors were developed by modulating the A&C ligands, resulting in emission centers ranging from 708 to 768 nm. The modified local environment of Cr3+ accounts for the increased light intensity (2.71 times) and broadening observed. Furthermore, this study investigated the impact of varying Cr3+ concentrations (Y2.6Ca0.4Ga4.6−xSn0.4O12:xCr3+) on the production of high-performance phosphors. Compared with Y3Ga4.93O12:0.07Cr3+, the optimized phosphor exhibited exceptional external quantum efficiency (EQE = 34.96%). The luminescence enhancement is attributed to an increase in radiative transitions caused by octahedral Jahn-Teller distortion, whereas the notable thermal stability (91.3% at 423 K) is attributed to the presence of weak electron-phonon coupling (EPC) and oxygen vacancy (OV) defects. Finally, by combining it with a 450 nm blue LED chip, we constructed a near-infrared phosphor-converted LED (NIR pc-LED) device with superior electroluminescence efficiency (18.8% @ 100 mA), increasing the ultralow quenching rate (< 5% intensity loss after 30 days of operation) and demonstrating remarkable performance in plant lighting applications.