Atomically precise bottom-up fabrication of graphene nanoribbons

Abstract

Graphene nanoribbons-narrow and straight-edged stripes of graphene, or single-layer graphite-are predicted to exhibit electronic properties that make them attractive for the fabrication of nanoscale electronic devices. In particular, although the two-dimensional parent material graphene exhibits semimetallic behaviour, quantum confinement and edge effects should render all graphene nanoribbons with widths smaller than 10 nm semiconducting. But exploring the potential of graphene nanoribbons is hampered by their limited availability: although they have been made using chemical, sonochemical and lithographic methods as well as through the unzipping of carbon nanotubes, the reliable production of graphene nanoribbons smaller than 10 nm with chemical precision remains a significant challenge. Here we report a simple method for the production of atomically precise graphene nanoribbons of different topologies and widths, which uses surface-assisted coupling of molecular precursors into linear polyphenylenes and their subsequent cyclodehydrogenation. The topology, width and edge periphery of the graphene nanoribbon products are defined by the structure of the precursor monomers, which can be designed to give access to a wide range of different graphene nanoribbons. We expect that our bottom-up approach to the atomically precise fabrication of graphene nanoribbons will finally enable detailed experimental investigations of the properties of this exciting class of materials. It should even provide a route to graphene nanoribbon structures with engineered chemical and electronic properties, including the theoretically predicted intraribbon quantum dots, superlattice structures and magnetic devices based on specific graphene nanoribbon edge states.

Bulk properties of solution-synthesized chevron-like graphene nanoribbons

“…2e) gives an optical band gap of $1.6 eV, which is very close to the theoretical band gap value of 1.57 eV that was previously calculated using the density functional theory (DFT) method. 9,19 The electrical measurements were performed on pressed GNR pellets using the home-built setup shown in Fig. 3a.…”

“…Several recent studies have focused on the synthesis of GNRs by the bottom-up approaches that rely on building GNRs from smaller molecular species. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] The resulting GNRs are very narrow (typically with widths, w < 2 nm) and have atomically precise edges, which is very important for potential applications. [3][4][5][6]21,22 One type of synthetic GNRs that has received considerable theoretical [23][24][25] and experimental attention 9,16,19,20,26 is the chevron-like GNR that has a very distinct periodic structure (Fig.…”

Plasmonics in atomically thin materials

“…Moving to the vis-NIR is challenging and requires patterning structures with sizes < 10 nm under realistically attainable doping conditions. In this respect, molecular self-assembly provides a viable way of synthesizing nanographenes in this size range [92][93][94][95]. Doped carbon nanotubes have also been predicted to display plasmons that are rather insensitive to their degree of chirality [45], and therefore, they provide a viable route towards the fabrication of large-scale tunable plasmonic structures operating in the vis-NIR regime.…”

Dehalogenation and Coupling of a Polycyclic Hydrocarbon on an Atomically Thin Insulator

“…12 Recent examples of this are the formation of graphene nanoribbons and porous graphene on metal substrates. [13][14][15] The synthesis of porous graphene is based on the molecular precursor 5,5′,5′′,5′′′,5′′′′,5′′′′′-hexaiodo-cyclohexa-mphenylene (I 6 -CHP, cf. inset in Fig.…”