Reconstruction of Mn4+-free shell achieving highly stable red-emitting fluoride phosphors for light-emitting diodes
Journal
Chemical Engineering Journal
Journal Volume
426
Date Issued
2021
Author(s)
Abstract
Poor humidity resistance is a bottleneck problem to be solved urgently for Mn4+ activated fluoride red phosphors. At present, some strategies such as outer coating, cation exchange (CE), and surface passivation (SP) have been developed, but the effect is limited. The key reason is that the easily hydrolyzed Mn4+ ions on the surface are difficult to be completely removed. With the goal of achieving a significant improvement in the moisture resistance of fluoride, this work proposes a new idea of using the reduction-assisted surface recrystallization (RSRC) strategy to construct a real core-shell structure without Mn4+ in the shell. The quantum efficiency (QE) of the K2SiF6:Mn4+ treated by the RSRC method is 99.95%. After boiling in water, the QE can even be maintained at 96.7%, which is significantly higher than that of the fluorides treated by CE (15.53%) or SP (62.64%) methods. The Mn-free shell is further determined by a combination of in-situ lift-out and STEM-EDX techniques. Finally, the aging results of LED devices in high temperature (85 °C) and high humidity (85%) environments further confirmed that the color stability of the K2SiF6:Mn4+ was significantly improved. ? 2021 Elsevier B.V.
Subjects
Core-shell
Fluoride
Light-emitting diodes
Moisture-resistance
Reduction-assisted surface recrystallization
Fluorine compounds
Light emission
Light emitting diodes
Manganese compounds
Passivation
Phosphors
Recrystallization (metallurgy)
Shells (structures)
% reductions
Cation exchanges
Core shell
Highly stables
Lightemitting diode
Moisture resistance
Surface passivation
Surface recrystallization
Moisture
SDGs
Type
journal article