Binary and ternary superlattices self-assembled from colloidal nanodisks and nanorods.

Self-assembly of multicomponent anisotropic nanocrystals with controlled orientation and spatial distribution allows the design of novel metamaterials with unique shape- and orientation-dependent collective properties. Although many phases of binary structures are theoretically proposed, the examples of multicomponent assemblies, which are experimentally realized with colloidal anisotropic nanocrystals, are still limited. In this report, we demonstrate the formation of binary and ternary superlattices from colloidal two-dimensional LaF3 nanodisks and one-dimensional CdSe/CdS nanorods via liquid interfacial assembly. The colloidal nanodisks and nanorods are coassembled into AB-, AB2-, and AB6-type binary arrays determined by their relative size ratio and concentration to maximize their packing density. The position and orientation of anisotropic nanocrystal building blocks are tightly controlled in the self-assembled binary and ternary lattices. The macroscopic orientation of the superlattices is further tuned by changing the liquid subphase used for self-assembly, resulting in the formation of lamellar-type binary liquid crystalline superlattices. In addition, we demonstrate a novel ternary superlattice self-assembled from two different sizes of nanodisks and a nanorod, which offers the unique opportunity to design multifunctional metamaterials.