Direct white-light from core-shell-like sphere with Sr3Mg-Si2O8: Eu2+, Mn2+ coated on Sr2SiO4:Eu2+

Abstract:

A method of color mixture for white light is presented with Sr₃MgSi₂O₈:Eu²⁺, Mn²⁺ shell coated on Sr₂SiO₄:Eu²⁺ core by spray pyrolysis procedure. Upon near ultraviolet (NUV) excitation, a 550 nm band emission of Eu²⁺ from core host combines with the simultaneous emissions of Eu²⁺ at 457 nm and Mn²⁺ at 683 nm based on energy transfer in the shell lattice to generate warm white light with color rendering index (CRI) of 91. With such a core-shell-like structure, the re-absorption of blue light from shell layer can be effectively suppressed, and the chemical stability of the phosphor is verified experimentally to be superior to that of the Sr₂SiO₄:Eu²⁺. This new proposed phosphor provides great potential in the color mixture of blending-free phosphor converted white NUV light emitting diode (LED) devices.