The synthesis of shape-controlled nanocrystals (NCs) with a wide range of compositions now yields semiconducting, magnetic, metallic, and dielectric NC that serve as ideal building blocks for the assembly of new mesoscale materials. These NCs can be thought of as "artificial atoms" who’s tunable electronic, optical, magnetic properties that are further enhanced/modified by the geometry of the NCs themselves and by the anisotropic coupling to neighboring NCs. In this talk, I will briefly outline the current state of the art in the synthesis of shape and size uniform NCs (single phase, core-shell (heterostructures, heterodimers, etc…). I will emphasize how tuning the shapes (spheres, rods, cubes, discs, octahedra, etc...) can control the NC packing arrangement and number of nearest neighbors (valence/hybridization) and the strength of coupling (bonding) to nearby NCs. We will explore the techniques (electron tomography and x-ray scattering) need to three-dimensionally characterize the NC geometries and the spatial arrangement of the particles in thin films and discrete superparticles. Specific attention will be focused on the design of complimentary NC shapes that self-assemble like the “pieces of a puzzle” to allow access to new combinations of multifunctional materials. Concepts of supermolecular ligand design will be highlighted as a route to program the organization of NCs through interactions that are not exclusively dictated by the under NC’s geometry allowing an expanded design space.

Valence and hybridization in artificial atoms: Controlling coupling and superstructure through shape directed nanocrystal assembly

256th National Meeting (2018)

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