Facile in situ synthesis of zeolite-encapsulating Cs2SiF6:Mn4+ for application in WLEDs

Abstract

Recently, topical Mn⁴⁺-activated fluoride red phosphors with unique narrow band emission and excellent luminous performance have been widely reported for application in white light-emitting diodes (WLEDs). However, the weak moisture-resistance of these composites is a significant challenge. Here, we report a zeolite-encapsulating Cs₂SiF₆:Mn⁴⁺ (CSFM-Y) composite with significantly improved moisture resistance, which is synthesized by a facile method of ion exchange and in situ precipitation inside the pores of the zeolite at room temperature. This method takes full advantage of the porous structure of the zeolite and the cation-exchangeable features within the pores. The 3D interconnecting pores of the zeolite allow CsSiF₆:Mn²⁺ (CSFM) to be well dispersed beneath the surface of the zeolite to give the emission, and the reduced size of the pores, owing to being partially occupied by CSFM crystals, provides an obstacle to further attack from water molecules. The stability test revealed that the luminous efficiency of WLEDs containing CSFM-Y reduces by only 4% after a duration of 120 h under high humidity (85%) and high temperature (85 °C) testing conditions, in comparison the luminous efficiency of the WLEDs fabricated using pure CSFM declines by 28%. This research reports a facile in situ synthesis approach for a CSFM-Y composite, which is promising for application in WLEDs.