Achieving high-performance far-red emission in Cr3+ activated garnet phosphor via Ca2+/Zr4+ doping toward plant lighting

Equimolar Ca2+ and Zr4+ doping was implemented to establish novel garnet-type Gd3‒xCaxAl2.95Ga2‒xZrxO12:0.05Cr3+ (x=0‒2.0) far-red (FR) phosphors. The quantum efficiency and temperature-dependent luminescence analysis successfully produced the optimal x=0.5 phosphor, which exhibited highly efficient (IQE=92.8%, EQE=31.6%) broadband FR-emission peaking at ~714 nm (full-width at half-maximum ~81 nm) and excellent thermal stability (95.5%@423 K) under 450 nm light excitation. Its performance is far superior to that of most reported Cr3+ activated FR-emitting garnet phosphors, and the emission spectrum can well superpose with the absorption band of the far-red phytochrome, making this phosphor have huge potential application in the construction of high-quality FR pc-LED used for plant lighting.