Photoluminescence efficiency significantly enhanced by surface modification of SiO2 coating on β-sialon:Eu2+ phosphor particle

The surface modification on the β-sialon:Eu2+ phosphor particles was successfully achieved by the SiO2 coating via a sol-gel method. The photoluminescence (PL) intensity of the phosphor was effectively enhanced and dominantly depending on the homogeneity of the SiO2 coating. It was found that more homogeneous and smooth SiO2 coating was responsible for higher PL intensity. The strongest emission intensity was obtained after the SiO2 homogenously coating under an optimized preparation condition of tetraethoxysilane (TEOS):H2O = 1:1 in molar ratio by improving ∼39% of intensity compared to that of the uncoated β-sialon:Eu2+ phosphor, due to effective elimination on the surface groups of the phosphor particles. However, with increasing the molar ratio of TEOS:H2O, the PL intensity of the coated phosphor became deteriorated owing to the poor homogeneity in the coating layer, even became lower than that of the uncoated sample when TEOS:H2O = 1:40 in molar ratio. This technique would be potentially applied in various phosphors assembling for the white light-emitting diodes by significantly improving their photoluminescence efficiencies.