Multifunctional Hydrophobic Surface for Achieving Record‐Setting Moisture Resistance of Fluorides Phosphor

Abstract In this work, K₂SiF₆:Mn⁴⁺@SA (KSF:Mn⁴⁺@SA, SA: stearic acid) phosphor with record‐setting moisture resistance (91.8% for 2880 h) and high thermal stability (88%@150 °C) is achieved by using SA as a superhydrophobic coating layer. Such a hydrophobic surface can not only prevent the luminescent centers from being eroded by external water but also greatly increase the specific surface area of the phosphor through its smart polyhedral modification, which increases the exposure of the luminescent centers to the incident light, thereby realizing a photoluminescence enhancement (1.5 times higher than the untreated sample) and excellent photoluminescence quantum yield (92.3%). The uniform polyhedral morphology with a shorter fluorescence lifetime enables the preparation of a high‐resolution pattern with a pixel size of 25 × 25 µm, implying great potential in high‐resolution (HR) inorganic light‐emitting diodes (LED) backlit and faster visible light communication. This work highlights the advances of multifunctional hydrophobic surface modification in tuning the photophysical properties of phosphors, with promising implications for a wide range of functional coating materials.