Surfactant- and HF-Free Cation Exchange Synthesis of Highly-Efficient Nanoscale K2SiF6:Mn4+ and Potential Usage for High-Resolution Micro-LED Display

Micro-LED technology is an advanced technology that can achieve high-resolution display in micron level pixels. The "phosphor-converted" mode is the most promising way to promote micro-LED applications, and efficient nanoscale fluorescent materials are of great importance. LED-used narrow-band red-emitting Mn4+ doped fluorides are commercialized worldwide and have excellent luminescent properties, but they lack an effective nanosynthesis method and experience difficulty in meeting the patterning requirements of a micro-LED high-resolution display. Herein, we report a surfactant-free stepwise cation exchange synthesis in a nonhydrofluoric acid system of cubic K2SiF6:Mn4+, with a high inner quantum yield of about 95% and average grain diameters below 100 nm. Thereafter, the as-obtained nano phosphor was dispersed and formed a stable red-emitting ink for printing high-resolution patterns with relatively uniform morphology and fluorescence. This study will provide technical reserves and open up a new path for the development of alternative red fluorescent materials for phosphor-converted micro-LED display applications.