Colloidal design: from colloidal molecules to material applications

Abstract:

Recent breakthroughs in the synthesis and design of colloidal building blocks allow the assembly of complex structures with unprecedented control over their architecture. In particular, patchy particles exhibiting highly directional interactions have emerged experimentally to assemble into “colloidal molecules” and open crystal structures, analogs of atomic molecules and compounds. Such assembly control promises insight into the atomic counterparts and a wealth of new materials with functionalities designed from the bottom up by structurural control at micrometer and nanometer length scales.

In this talk, I will show how fine control over directional bonding allows building colloidal molecules and investigating their equilibrium reactions directly in real space and time. Using tetramer particles, we assemble analogs of well-known sp³-hybridized carbon compounds such as (cyclo)butane, butyne, cyclopentane, and cyclohexane. Adsorbed at a substrate, the particles become pseudo-trivalent, and assemble into analogs of two-dimensional materials such as graphene. Applied to the nanoscale, this control can assemble quantum dots whose collective electronic states give rise to new phenomena and material properties such as superfluorescence and new electronic and optical states that depend on the structure and quantum-mechanical coupling in the assembled packing. These results demonstrate the opportunities for optoelectronic applications and exciting new science that can be explored with these novel colloidal architectures.