Triclinic nematic colloidal crystals from competing elastic and electrostatic interactions

TL;DR

This paper demonstrates the self-assembly of triclinic nematic colloidal crystals from inorganic nanocrystals by balancing elastic and electrostatic interactions, enabling controlled large-scale anisotropic structures.

Contribution

It introduces a method to create low-symmetry triclinic colloidal crystals with tunable orientation by combining elastic and electrostatic forces in a nematic host.

Findings

Triclinic colloidal crystals have lattice periodicity much larger than nanoparticle size.

Nanocrystal orientations are coupled to the nematic host alignment.

Emergence of triclinic crystals from competing elastic and electrostatic interactions.

Abstract

Self-assembly of nanoparticles can enable composites with pre-designed properties but remains challenged by reproducing structural diversity of atomic and molecular crystals. We combine anisotropic elastic and weakly screened electrostatic interactions to guide both orientational and triclinic positional self-ordering of inorganic nanocrystals in a nematic fluid host. The lattice periodicity of these low-symmetry colloidal crystals is more than an order of magnitude larger than the nanoparticle size. Orientations of nanocrystals, as well as crystallographic axes of ensuing triclinic colloidal crystals, are coupled to the uniform alignment direction of the nematic host, which can be readily controlled on large scales. We probe colloidal pair and many-body interactions and demonstrate how triclinic crystals with orientational ordering of the semiconductor nanorods emerge from competing long-range elastic and electrostatic forces.