A Quest for Structurally Uniform Graphene Nanoribbons: Synthesis, Properties, and Applications

Abstract

Graphene nanoribbons are the class of next-generation carbon materials that are attracting many researchers in various research fields. Their unique properties, such as band gap, conductivity, carrier mobility, thermal conductivity, spin polarization, and on−off behavior, heavily depend on structural factors such as edge structure, width, and length. Therefore, the synthesis of graphene nanoribbons with control over these structural factors with atomic precision is crucially important. Among various synthetic approaches, bottom-up synthetic methods such as on-surface polymerizations and solution-phase polymerizations represent promising ways to control the width, length, and edge structure of graphene nanoribbons. In this Perspective, we introduce the recently reported bottom-up synthetic methods for graphene nanoribbons and the theoretical and experimental research on those physical properties and applications. Reviewing these researches along with highlighting advantages and limitations, we emphasize how structurally controlled synthesis is important and provides future outlooks in graphene nanoribbon science.

Graphene Nanoribbons: On‐Surface Synthesis and Integration into Electronic Devices

“…In this article, we summarize the latest developments and updates, mainly focusing on the field of on‐surface synthesis of GNRs. In view of the dynamics of the field, readers are referred to previous review articles published by us [ 11,12,25,26,49–51 ] and others [ 10,52–56 ] for a detailed description of the preceding works. Here, we start with the recent progress in the surface‐assisted synthesis of GNRs under UHV and CVD conditions.…”

Synthesis of conjugated polymers via cyclopentannulation reaction: promising materials for iodine adsorption

“…[36][37][38][39][40] Various conjugated polymers have been reported with structures ranging from linear, 14,41 hypercrosslinked, 42 organic frameworks, 25,43 to polycyclic aromatic hydrocarbons. [44][45][46][47][48] Nevertheless, the rigidity and stiffness of these polymers make them poorly soluble, which can be circumvented by the introduction of aliphatic side chains in order to improve their solubility in common organic solvents. However, the insertion of long peripheral chains hampers microporosity since these latter block the intrinsic pores.…”

On‐surface Synthesis of a Chiral Graphene Nanoribbon with Mixed Edge Structure

“…Graphene nanoribbons (GNRs), ribbon‐shaped cut‐outs of graphene with nanometre‐scale widths, have attracted much attention due to their unique (opto)electronic properties, and have been recognized as a promising material for next‐generation electronics [1] . Their properties, such as chemical stability, optical absorption and emission, charge‐carrier mobility, and spin state, heavily depend on their geometrical features such as edge structure, width, and length [1e,f,j,2] . The edge structure is the most critical factor for the properties of GNRs, making armchair‐edge GNRs (AGNRs) semiconducting with width‐dependent bandgaps and zigzag‐edge GNRs (ZGNRs) potentially magnetic thanks to their edge‐localized states that can be spin polarized [2a,3] .…”

“…Because structural control at the single‐atom level is essential to obtain GNRs with desired properties, conventional top‐down nanofabrication methods (e. g., patterning of graphene or unzipping of carbon nanotubes) fail to furnish GNRs with defined and singly hydrogenated edges [2e,8] . In contrast, bottom‐up synthesis can provide GNRs with atomically precise widths, edge structures and chemical functionalization, thus attracting increasing attention over the past decade [1a,f,9] …”