Efficient and Thermally Stable Cr3+-Doped Phosphor Achieved by Cation Substitution: Plant Lighting Application

Far-red phosphor-converted light-emitting diodes are receiving increasing attention as an essential component of the next-generation plant-growth lights. However, developing far-red phosphors with high quantum efficiency, low thermal quenching, and suitable emitting wavelength is crucial and urgent. Herein, a new far-red phosphor BaY2Ga3.9GeO12:0.1Cr3+ with high internal quantum efficiency (98%) and thermal stability (92.17%@423K) is obtained via the substitution of CaO8 with bigger BaO8 dodecahedrons, which is attributed to variations in the lattice environment of Cr3+. Meanwhile, controllable emission tuning from 780 to 708 nm and enhanced luminescence performance are achieved due to the cation substitution can reduce the production of Cr4+ and modulate the lattice occupancy of the Cr3+ ions, and the enhancement of metal-ligand interactions resulting in the enhancement of the crystal field and the breaking of the forbidden d-d transition of Cr3+. The proof-of-concept demonstration of the pakchoi lighting experiment reveals the great potential of BaY2Ga3.9GeO12:Cr3+ phosphor in stimulating plant growth and pushing the yield. These results demonstrate the feasibility of cationic substitution to optimize the optical performance of Cr3+-doped phosphors, providing an alternative strategy for designing efficient far-red light sources for plant lighting.