Lawrence Berkeley National Laboratory

The potential optoelectronic applications of perovskite nanocrystals (NCs) are primarily limited by major material instability arising from the ionic nature of the NC lattice. Herein, we introduce a facile and effective strategy to prepare extremely stable CsPbX3 NC-polymer composites. NC surfaces are passivated with reactive methacrylic acid (MA) ligands, resulting in the formation of homogeneous nanocubes (abbreviated as MA-NCs) with a size of 14-17 nm and a photoluminescence quantum yield above 80%. The free double bonds on the surface then serve as chemically addressable synthetic handles, enabling UV-induced radical polymerization. Critically, a bromide-rich environment is developed to prevent NC sintering. The composites obtained from copolymerizing MA-NCs with hydrophobic methyl methacrylate and methacrylisobutyl polyhedral oligomeric silsesquioxane monomers exhibit enhanced properties compared to previously reported encapsulated NCs, including higher quantum yields, remarkable chemical stability toward water, and much enhanced thermal stability. The good solubility of the composite in organic solvent further enables its use as a solution-processable luminescent ink, used here for fabrication of white-light-emitting diodes with high luminous efficiency and excellent color-rendering index. The resulting fluorescent and stable NC ink opens the door to potential scalable and robust optoelectronic applications.