Interfacial self-assembly of atomically precise graphene nanoribbons into uniform thin films for electronics applications

Because of their intriguing electronic and optical properties, atomically precise graphene nanoribbons (GNRs) are considered to be promising materials for electronics and photovoltaics. However, significant aggregation and low solubility of GNRs in conventional solvents result in their poor processability for materials characterization and device studies. In this paper, we demonstrate a new fabrication approach for large-scale uniform thin films of nonfunctionalized atomically precise chevron-type GNRs. The method is based on (1) the exceptional solubility of graphitic materials in chlorosulfonic acid and (2) the original interfacial selfassembly approach by which uniform films that are single-GNR (∼2 nm) thick can be routinely prepared. These films can be transferred to various substrates including Si/SiO₂ and used for the streamlined fabrication of arrays of GNR-based devices. The described self-assembly approach should be applicable to other types of solution-synthesized atomically precise GNRs as well as large polyaromatic hydrocarbon (PAH) molecules and therefore should facilitate and streamline their device characterization.