Self-assembly of CdTe nanoparticles into sheets and wires: Role of anisotropy

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Zhenli Zhang, zlzhang@umich.edu, Zhiyong Tang, Nicholas A. Kotov, kotov@umich.edu, and Sharon C. Glotzer. Department of Chemical Engineering, University of Michigan, 2300 Hayward Street, Ann Arbor, MI 48109-2136
By controlling the organic stabilizers on the surfaces of CdTe nanodots, these particles are found in experiments to self-assemble into one-dimensional wires and two-dimensional sheets[1,2]. To explore the underlying mechanisms for the formation of the two structures we perform simulations on multiple scales ranging from quantum mechanics to mesoscale stochastic simulations. The simulations and corresponding energy analysis demonstrate that a delicate balance of anisotropic forces between nanoparticles is responsible for the different nanostructures they form. In particular, we show how nanoparticle shape, directional hydrophobic attraction, and electrostatic interactions determine the anisotropy of the interaction and final self-assembled structures. Based on our findings, we propose design rules for the fabrication of nanocolloidal atoms and molecules.