Significantly enhanced the humidity resistance of a novel red phosphor CsNaGe0.5Sn0.5F6:Mn4+ through surface modification

Abstract

The luminescence performance of phosphors CsNaGe x Sn 1-x F 6 :Mn 4+ can be tailored by controlling the different addition ratios of the central ions Ge 4+ /Sn 4+ . A feasible strategy for improving the humidity resistance of Mn 4+ doped double-composite fluoride phosphors has been developed. • A new phosphor of CsNaGe x Sn 1-x F 6 :Mn 4+ (CNGSFM) obtained at room-temperature. • The luminescence performance can be tailored by controlling the ratios of Ge 4+ /Sn 4+ . • A facile strategy to improve the humidity resistance of phosphor CNGSFM. • The quenched luminescence of the CNGSFM can be restored through surface modification. Red phosphors based on Mn 4+ doped fluorides emitting narrow red light under the excitation of blue GaN chips, which can help to improve the luminescence efficiency and color rendering index (CRI) of white light-emitting diodes (WLEDs). In this paper, we carried out a room-temperature synthesis method to obtain a new phosphor of CsNaGe x Sn 1-x F 6 :Mn 4+ (CNGSFM) which contains double-central ions Ge 4+ and Sn 4+ . By controlling the different ratios of the central ions Ge 4+ /Sn 4+ , the contraction and expansion of the matrix lattice CNGSF can be freely changed, which provides a new direction for exploring the trimming method of the lattice effect on the luminescence performance of phosphors. Mn 4+ in CNGSFM shows weak stability and its luminescence quenches fastly in humid environments, so that we explored a facile strategy to improve its humidity resistance. Furthermore, the quenched luminescence of the CNGSFM can be restored through surface modification. Therefore, our results not only establish the tunable mechanism between luminescence performance and microstructure, but also provide a feasible strategy to improve the humidity resistance of Mn 4+ doped double-composite fluoride phosphors.