Micro-scale 2D quasi-nanosheets formed by 0D nanocrystals: from single to multicomponent building blocks

Self-assembly of colloidal nanocrystals (NCs) into large-scale superlattices with complex and controllable structures has attracted extensive attention due to their collective properties and promising device applications. Plasmonic NCs are very popular for long-range ordered superstructures by virtue of their collective nanogaps for electromagnetic field enhancement, in particular bulk-scale single-layer assembly. Large-area two-dimensional (2D) quasinanosheets (QNSs) composed of mono-component Au NCs or multi-component Au@ZnS core-shell hetero-nanocrystals (HNCs) were successfully prepared, via careful solvent evaporation-induced interfacial self-assembly. The entire self-assembly process was carried out on the liquid-air surface and mediated simply by tuning the operating temperatures and concentrations of the NCs. Specifically, monolayer and double-layer 2D QNSs in tens of micrometers scale with different stacking models were fabricated by precisely controlling the solvent evaporation rate and colloidal concentration.