Surface passivation to improve the water resistance and fluorescent thermal stability of K2SiF6:Mn4+ by using Na2S2O4 as a passivator

Mn4+ doped fluoride emitting red phosphors are important component for commercial white light emitting devices (WLEDs), but the poor moisture resistance and fluorescent thermal stability are the main obstacles for such phosphors in practical applications. In this study, a strategy for passivating K2SiF6:Mn4+ (KSF:Mn4+) phosphor with Na2S2O4 is proposed. After passivation, a protective layer is formed on the surface of the phosphor, which significantly enhances the water resistance and fluorescent thermal stability of the optimal sample. The passivated sample can maintain 86.1% of the initial intensity when immersed in water for 6 h, and the fluorescence intensity at 180 °C is 4.11 times of the initial one at 30 °C. The LED package emits a warm white light with good performances. These results show that it has important potential applications in the field of WLED backlighting and displays. © 2022 Elsevier B.V.