A far-red emission (Ca,Sr)14Zn6Ga10O35:Mn4+ phosphor for potential application in plant-growth LEDs

To facilitate phosphor-converted light-emitting diodes (LEDs) for plant growth, the development of phosphor materials with efficient red or far-red emission is essential. Herein, we report a novel Ca13.6Sr0.4Zn6Ga9.85O35:0.15Mn(4+) (CSZG:Mn4+) phosphor with far-red emission synthesized via the traditional solid-state reaction. The structure, morphology and the effect of dopant concentration on the photoluminescence properties of CSZG:Mn4+ were systematically investigated. These phosphors can efficiently be excited by near-ultraviolet (NUV)/blue LED chips, and exhibit highly efficient red emission in the range of 650-760 nm, which matches well with the absorption band of phytochrome. The as-fabricated LED, comprising the CSZG:Mn4+ phosphor and a 460 nm blue InGaN chip, emits bright blue and red light. Owing to their high quantum efficiency (QE) value (similar to 75.8%), excellent thermal stability (similar to 97.9% at 425 K relative to that at RT), non-rare earth materials and mild preparation conditions, the CSZG:Mn4+ phosphors have great potential as far-red emission phosphors in high-power plant growth LEDs.