Highly Stable and Monodispersed Silica-Coated CsPbBr₃ Perovskite Quantum Dots as Ultraefficient Light Conversion Phosphors for Micro-Light-Emitting Diodes

Silica coating is widely employed to improve the stability of perovskite quantum dots (PQDs) as light conversion phosphors. When used in combination with micro-light-emitting diodes (micro-LEDs) for next-generation displays, however, most silica-coated PQDs (Si-PQDs) face some challenges: (i) polarity mismatch between silica and organic solvent undermines the fabrication of the phosphor film by unstable PQD ink; (ii) aggregation-induced large particle size hinders the micron-scale processability. Herein, we report a ligand-assisted silica-coating strategy to prepare highly monodispersed Si-PQDs for micro-LEDs. Briefly, pristine CsPbBr₃ QDs capped with aminosiloxane were first formed followed by surface passivation with the zwitterionic ligand lecithin and subsequent tetramethoxysilane-mediated silica coating. The as-prepared Si-PQDs were highly monodispersed with well-defined core-shell structure, exhibiting uniform rectangular morphology, narrow-band green emission, ultrahigh photoluminescence quantum yield (∼98%), and high stability against light and water. Importantly, the Si-PQDs were well dispersed in organic solvents, which could not only be fabricated into white LEDs and screen-printed patterns but also patterned into uniform 20 μm pixels using a microfluidic technique. These results demonstrate that the one-pot synthesized Si-PQDs are very promising light conversion phosphors for micro-LED-based displays and solid-state lighting.