Switchable supramolecular assemblies on graphene

Abstract

We studied the self-assembly of trimesic acid on single- and few-layer graphene supported by SiO₂ substrates. A scanning tunneling microscope operated under ambient conditions was utilized to image supramolecular networks of trimesic acid at liquid–graphene interfaces. Trimesic acid can self-assemble into large-scale, highly ordered adlayers on graphene surfaces. Phase transition of the trimesic acid adlayer from a close-packed structure to a porous chicken-wire structure was observed by changing from single- to few-layer graphene, which was attributed to the modulation of molecule–graphene interactions by the layer number of graphene. The guest-induced phase transition of trimesic acid by complexation with coronene on single-layer graphene further confirms that supramolecular networks on graphene can be rationally tailored with sub-nanometer resolution by balancing between intermolecular vs. molecule–graphene interactions. We further investigated the effects of trimesic acid adlayers on the electronic transport properties of graphene transistors. The adsorption of trimesic acid induces p-doping and defects in the adlayers cause scattering of charge carriers in single-layer graphene.