Dual deep red and far red emitting Cr-doped garnet-perovskite based phosphors with excellent responsiveness to P(fr) for plant growth LED lighting.

Cr(3+)-activated phosphors, with their 3d(3) electronic configuration, efficiently absorb blue/violet light and emit deep to far-red wavelengths, perfectly matching the optimal absorption bands for plant growth. In this work, we report the synthesis of Y(3)Al(5)O(12)-YAlO(3):1.3%Cr(3+) (YAG-YAP:Cr(3+)) phosphors exhibiting a broad emission spanning deep to far-red light, closely aligned with the far-red phytochrome (P(fr)) absorption spectrum in plants. The optimized sample, sintered at 1600 °C for 5 hours, demonstrates outstanding photoluminescence performance, including an exceptional activation energy of 0.34 eV, a long luminescence lifetime of 1.86 ms, perfect color purity (100%), and a high internal quantum efficiency of 74.9%. A prototype plant-growth LED was fabricated by coating this phosphor onto a 415 nm violet LED chip, achieving a strong spectral overlap (65% SR index) with the P(fr) absorption band. These results demonstrate that YAG-YAP:Cr(3+) phosphors are highly promising candidates for efficient, targeted far-red LEDs tailored for enhanced plant cultivation.