Self-assembly of nanocrystals into functional materials requires precise control over nanoparticle interactions in solution, which are dominated by organic ligands that densely cover the surface of nanocrystals. In this talk, I will present a computational study of ligand effects in the self-assembly of small, non-spherical nanocrystals. We focus on nanocrystals with cuboctahedral and truncated octahedral shape and determine their self-assembly behavior as a function of ligand length and solvent quality. Our model, which is based on a coarse-grained description of ligands and a schematic representation of solvent effects, reproduces the experimentally observed superstructures, including recently observed superlattices with partial and short-ranged orientational alignment of nanocrystals. We show that small differences in nanoparticle shape, ligand length and coverage, and solvent conditions, can lead to markedly different self-assembled superstructures due to subtle changes in the free energetics of ligand interactions. Our results help explain the large variety of different reported superlattices self-assembled from seemingly similar particles and can serve as a guide for the targeted self-assembly of nanocrystal superstructures.

Orientational order in self-assembled nanocrystal superlattices

2019 Spring National Meeting

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