HF‐Free Microwave‐Assisted Synthesis of Nano‐Micro‐Sized K2SiF6:Mn4+ for MicroLED Color Conversion

Abstract Micro‐light‐emitting diodes (MicroLED) are considered to be the next generation of ideal display devices, with chip size requirements of less than 50 µm. To meet its micron‐scale pixel size, submicron luminescent materials are needed. Mn 4+ doped fluoride phosphor, K 2 SiF 6 :Mn 4+ (KSFM) as a red luminescent material with excellent narrow‐band emission sensitivity to human eyes, has great potential as a color conversion material for full‐color MicroLED. However, it is difficult to obtain small‐size KSFM efficiently by conventional synthesis methods. Here, a simple HF‐free strategy for the rapid batch synthesis of nano‐micro‐sized KSFM based on a microwave‐assisted method is reported. The synthesized KSFM shows uniform morphology, average particle size is less than 0.2 µm, and has 89.3% internal quantum efficiency under 455 nm excitation. It exhibits excellent thermal stability (97.4%@423 K of the integrated emission intensity at 298 K) and prominent moisture resistance (81.9% of its initial relative emission intensity after immersing in water for 30 min). By employing it as a red emitter, the authors fabricate high‐performance white LEDs with high luminous efficacy of 116.1 lm W −1 and wide color gamut of 130.4% NTSC. In addition, self‐luminous red‐emitting arrays with a pixel size of 20 × 40 µm are constructed by nanoimprinting as‐synthesized KSFM.