Formation of long-range-ordered nanocrystal superlattices on silicon nitride substrates

Particle-particle and particle-substrate interactions cause nanocrystals to self-assemble into superlattice structures upon drying from a colloidal suspension on a solid surface. Rapid dewetting of a volatile solvent, however, can significantly undermine the degree of ordering. We demonstrate here that by increasing the concentration of the nonvolatile dodecanethiol ligand, dewetting can be controlled and gold nanocrystal superlattices can be formed on silicon nitride substrates with long range ordering over several microns. Monolayer and bilayer superlattices can be produced by adjusting the nanocrystal concentration. The superlattice structures are robust and are not perturbed by the final dewetting of the solvent.