Graphene-Molecule Hybrid Structures

Graphene and organic molecules can combine to form novel hybrid nanostructures via a self-assembly process in which the adsorbate (the molecules) and substrate (graphene) interchange roles during assembly, according to chemists at the National University of Singapore (ACS Nano, DOI: 10.1021/nn101800n). Shuai Wang, Bee Min Goh, Kian Ping Loh, and coworkers report that when the planar aromatic compound perylenedicarboximide (PDI) is deposited from solution onto an oxidized form of graphene, π-π interactions between PDI and graphene cause the PDI molecules to nucleate and grow into wires. As the process continues and the wires’ dimensions outgrow the supporting graphene flake, the same type of noncovalent interaction drives other graphene flakes to adsorb onto and coat the growing wire. In a test of the wires’ properties, the team used them to fabricate organic photovoltaic cells. Compared with the individual components and with simple PDI-graphene mixtures, the hybrid-wire structures give the best-performing solar cells, the team says.