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

Highlights: • Surface modification on β-sialon:Eu²⁺ phosphor was achieved by SiO₂ coating. • Photoluminescence intensity of phosphor was effectively enhanced by SiO₂ coating. • Emission intensity was dominantly depending on homogeneity of SiO₂ coating. • More homogeneous and smooth SiO₂ coating was responsible for higher PL intensity. 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.