ABSTRACT
Anisotropic colloidal crystals are materials with novel optical and electronic properties. However, experimental observations of colloidal single crystals have been limited to relatively isotropic 1018habits. Here, we show DNA-mediated crystallization of two types of nanoparticles with different hydrodynamic radii that form highly anisotropic, hexagonal prism microcrystals with AB2 crystallographic symmetry. The DNA directs the nanoparticles to assemble into a nonequilibrium crystal shape that is enclosed by the highest surface energy facets (AB2(1010) and AB2(0001)). Simulations and theoretical arguments show that this observation is a consequence of large energy barriers between different terminations of the AB2(1010) facet, which results in a significant deceleration of the (1010) facet growth rate. In addition to reporting a hexagonal colloidal crystal habit, this work introduces a potentially general plane multiplicity mechanism for growing nonequilibrium crystal shapes, an advance that will be useful for designing colloidal crystal habits with important applications in both optics and photocatalysis.
