Electric Field Assembly of Colloidal Superstructures

Abstract

The\nassembly of materials from building blocks has been in the\ncore of a wide range of applications from catalysis to photonics and\nelectronics. External electric fields enable the interactions between\nbuilding blocks to be controlled via induced dipoles. Dipolar interactions\nwere used so far to obtain one-dimensional chains or three-dimensional\nnon-close-packed lattices. However, complex colloidal assemblies and\nclusters of simple spherical particles are rare. Here we demonstrate\na novel self-assembly approach enabling the formation of regular axially\nsymmetric clusters, an array of colloidal assemblies as per design\nof posts, and hierarchical complex assemblies by using posts and dipolar\ninteractions or combining them. Regulating the polarization of the\nparticles from positive to negative allows us to control the interparticle\ninteractions from attractive to repulsive at the poles or equator\nof the particles. Therefore, such particle–particle interactions\nenable switching between Saturn ring-like and candle-flame-like axially\nsymmetric assemblies, which could potentially be exploited for display\napplications.