Co-Substitution Strategy to Achieve a Novel Efficient Deep-Red-Emitting SrKYTeO ₆:Mn ⁴⁺ Phosphor for Plant Cultivation Lighting

Mn4+-doped oxide phosphors with bright red emissions show promising application potential in plant cultivation lighting. However, finding suitable oxide hosts for Mn4+ ions incorporation is still a challenge. Herein, for the first time, an efficient deep-red-emitting SrKYTeO6:Mn4+ phosphor was achieved through the co-substitution of [K+−Y3+] for [Sr2+−Ca2+] in non-luminous Sr2CaTeO6:Mn4+. Crystal structure analysis reveals that the new SrKYTeO6 compound is isostructural to Sr2CaTeO6, which belongs to the monoclinic P21/ n (14) space group. Upon 338 nm excitation, the SrKYTeO6:Mn4+ phosphor exhibits a deep-red emission band peaking at 680 nm, resulting from the 2Eg → 4A2g transition of Mn4+ ion. The composition of this phosphor is optimized to be SrKYTeO6:0.4%Mn4+, and its color purity and internal quantum efficiency (IQE) reach as high as 98.5% and 44.3%, respectively. The phosphor also possesses good thermal stability with the emission intensity at 423 K maintaining 56% of the initial value at 298 K. These superior luminescent properties could be attributed to the change of local crystal environment induced by distorting the internal [TeO6] octahedra. This work not only acquires an efficient SrKYTeO6:Mn4+ phosphor for application in plant cultivation lighting but also offers a replicable strategy for further exploring novel Mn4+-doped perovskite phosphors.