In Situ Formation of Ultrathin Composite Shell with Strong Water Resistance on the Surface of K 2 SiF 6 :Mn 4+ via NaClO Treatment

Solving the problem of poor weather resistance of Mn 4+ ‐doped fluoride phosphors is pivotal for their application in white‐light‐emitting diodes (WLEDs). This study introduces a one‐step synthesis strategy for the phosphor T‐KSF:Mn (KSF:M = K 2 SiF 6 :Mn 4+ and T = surface‐treated with NaClO) that involves the use of a NaClO solution as a treatment agent to augment the water resistance of this phosphor. The results of transmission electron microscopy, electron diffraction tomography, and X‐ray photoelectron spectroscopy, analyses reveal the formation of an ultrathin composite shell (