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

Cr-activated phosphors, with their 3d 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 YAlO-YAlO:1.3%Cr (YAG-YAP:Cr) phosphors exhibiting a broad emission spanning deep to far-red light, closely aligned with the far-red phytochrome (P) 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 absorption band. These results demonstrate that YAG-YAP:Cr phosphors are highly promising candidates for efficient, targeted far-red LEDs tailored for enhanced plant cultivation.