Atomic site engineering in garnet phosphors taming thermal quenching for high-power visible and NIR luminescence

Rare-earth (RE) and transition metal-doped garnet phosphors are the dominant commercial luminescent materials for high-power white light-emitting diodes (wLEDs), and emerging near-infrared (NIR) phosphors for spectroscopy, bioimaging and plant lighting. A long-standing bottleneck for high-power operation is thermal quenching: commercial YAG:Ce 3+ typically loses >20% of its room-temperature emission intensity at 150 °C, the standard operating temperature of 1 A-driven pc-LEDs, leading to efficiency roll-off, color shift and shortened device lifetime. Unlike passive strategies such as surface coating or glass encapsulation, site engineering modulates the local coordination environment of luminescent centers at the atomic scale, providing an intrinsic route to improve thermal stability without sacrificing quantum efficiency. This mini review summarizes the structure-property relationship between crystallographic site properties and thermal quenching behavior, critically evaluates three mainstream site engineering approaches (isovalent substitution, aliovalent charge-compensated co-doping, multi-site occupancy design) with representative material systems covering both RE (Ce 3+ , Eu 3+ ) and transition metal (Cr 3+ , Mn 2+ /Mn 4+ ) activators, and highlights unresolved research gaps.