The effects of silica-coated Y2O2S:Eu3+ red phosphor on the lighting properties of the light-emitting diode

Abstract

The red phosphor Y₂O₂S:Eu³⁺ coated with silica (SiO₂) nanocomposite was synthesized using the sol-gel method with dip-coating technique. The purpose of coating the poly (methyl methacrylate) (PMMA)-SiO₂ composite on Y₂O₂S:Eu³⁺ phosphor’s surface is to protect the phosphor and improve its scattering ability. The three primary ingredients of coating composition include methyl methacrylate (MMA) monomer, tetraethyl orthosilicate (TEOS), and SiO₂ nanoparticles. Via Mie scattering theory, the scattering of SiO₂ is examined, which primarily determines the scattering of PMMA-SiO₂-coated Y₂O₂S:Eu³⁺. The larger particles of SiO₂ in the coating composite leads to better scattering properties. When being applied in the dual-film remote phosphor configuration of a LED, SiO₂@Y₂O₂S:Eu³⁺ considerably enhances the CRI and the color quality scale (CQS). The highest CRI and CQS can be observed at approximately 85 and 74 with 23 %wt. and 26 %wt. the concentration of SiO₂@Y₂O₂S:Eu³⁺, respectively. Neverthless, the illuminating beam of the package gradually declines as the concentration of SiO₂@Y₂O₂S:Eu³⁺ go up, which might be ascribed to excessive scattering occurrences in the double-layer remote package.