Surface engineered environment-stable red-emitting fluorides for white light emitting diodes

Surface lattice enhancement of red-emitting fluorides enabled by embedding small cations

“…S6 †), indicating that Ge 4+ is more easily embedded on the surface of KTFM than Si 4+ , because the ionic radii of Ge 4+ is closer to that of Ti 4+ . In addition, Mn 4+ on the surface of KTFM can be quickly reduced to Mn 2+ in the reaction solution by GA. 44 Therefore, the Mn 2p XPS signal on the surface of KTFM treated by RSRC is significantly inhibited (Fig. 2D and Fig.…”

Advancing Red-Emitting Fluoride Phosphors for Highly Stable White Light-Emitting Diodes: Crystal Reconstruction and Covalence Enhancement Strategy

“…One significant challenge for ionic fluoride crystals containing [MnF 6 ] 2– is their high propensity to react with water, forming brown-black oxygen-containing compounds that drastically reduce luminescence efficiency. This limitation severely restricts their broad implementation in WLED devices. − Current strategies to address moisture resistance primarily focus on surface-based techniques, such as outer coating, − surface passivation, , and constructing a shell with minimal or no Mn 4+ presence to effectively isolate [MnF 6 ] 2– from water molecules. , Recently, our group developed a novel reduction-assisted surface recrystallization method, enabling the reconstruction of a Mn 4+ -free K 2 SiF 6 inert shell on K 2 SiF 6 :Mn 4+ crystals . The resulting core–shell structure exhibited exceptional stability, maintaining a QE of 97% even after boiling in water for 20 min.…”