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Sulfide-based phosphors have widely used for LED phosphors. To prevent degradation of sulfide phosphors from light source is important issue for LED applications. In this study, red phosphors SrS:Eu and CaS:Eu were coated with a SiO2 layer to improve their stability and luminescent properties using PVP (polyvinylpyrrolidone) in n-butanol solution. The SiO2 coatings on sulfide phosphors were prepared by sol-gel method using tetraethyl orthosilicate (TEOS) and diethoxydimethylsilane (DEDMS) as the precursor materials. The film-like coating was formed on the surface of phosphors in case of TEOS and particle-like coating was obtained by DEDMS. Various SiO2 concentrations (0.5, 1.0, 2.0, and 5.0 wt%) were employed and their effects on the photoluminescence (PL) performance were investigated. In addition, the coatings were further characterized by FE-SEM, FT-IR and TEM.
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