Water resistance, thermal stability, luminescence enhancement of core-double shell structure K2TiF6:Mn4+ phosphor

In order to improve fluorescent thermal stability and water-proof of Mn4+-doped red emitting fluoride phosphors applied for white light emitting diodes (WLEDs), in this work, a coating strategy is explored to prepare graphene quantum dots (GQDs) and K2TiF6 double coated Mn4+ doped K2TiF6 red emitting phosphor with high efficiency, fluorescent thermal stability and water-proof. After coating with double shell of GQDs and K2TiF6, fluorescent intensity, fluorescent thermal stability and water-proof are remarkably improved. The mechanism of the above improvements is explained and suggested. The results implied that double coating by GQDs and matrix is an effectively way to obtain Mn4+-doped fluoride phosphors with high emission, fluorescent thermal stability and water-proof at the same time.