A novel double-perovskite LiLaMgTeO6: Mn4+ far-red phosphor for indoor plant cultivation white LEDs: Crystal and electronic structure, and photoluminescence properties

Deep-red-emitting Mn4+ activated oxide phosphors are the hot research topic due to their potential applications in indoor plant cultivation LEDs. In this paper, a novel double-perovskite LiLaMgTeO6:Mn4+ phosphor was firstly prepared by high-temperature solid-state reaction method and its structure of the phosphor was determined by X-ray diffraction (XRD) and Rietveld refinement. Density functional theory (DFT) calculations using VASP provide an insight into the bandgap and electronic structures of the LiLaMgTeO6 host. Under UV or blue excitation, LiLaMgTeO6:Mn4+ shows a good stability and bright far-red light in the 540–800 nm range with the maximum at 708 nm, which matches well with the absorption band of phytochrome PFR, indicating its potential application in improving plant growth. The optimal Mn4+ doping concentration was approximately 0.6 mol%. Furthermore, a white-LEDs device made of a 365 nm chip coated with present phosphor and commercial green, blue phosphors was designed for indoor plant cultivation. The results indicate that the LiLaMgTeO6: Mn4+ phosphor possesses great application prospect in white-LEDs for plant cultivation.