Feasible preparation of red-phosphor K₂SiF₆:Mn⁴⁺ coated with SiO₂ for white light emitting diodes application

Abstract

We report a facile approach for coating K₂SiF₆:Mn⁴⁺ red-phosphor with a moisture-resistant silica layervia the one-step co-precipitation using tetraethyl orthosilicate (TEOS) and sodium dodecyl benzene sulphonate (SDBS) surfactant. The bare K₂SiF₆:Mn⁴⁺ (KSF) phosphor with nearly round-shape and 10 µm diameter, showed a high external quantum yield ~0.502 under 460 nm light excitation. The 40 nm- and 80 nm-thick SiO₂ coatinglayers on the phosphor surface was observed via transmission electron microscopy (TEM). The K₂SiF₆:Mn⁴⁺ coated with SiO₂ (KSF@SiO₂) phosphor possesses bright red emission at approximately 630 nm, high thermal stability and excellent waterproof. Effect of coating layer-thickness on photoluminescence properties of the prepared phosphors have been investigated and discussion.