Tuning the Electronic Properties of Atomically Precise Graphene Nanoribbons by Bottom‐Up Fabrication

Abstract

Graphene, a monolayer of graphite, is predicted to be one of the most promising materials to replace silicon in future electronic instruments. Despite its extraordinary electronic and thermal properties, the lack of an electronic band gap severely hampers its potential for applications in digital electronics. In contrast, narrow stripes of graphene, so called graphene nanoribbons (GNRs) are semiconductors, due to the quantum confinement with the tunable band gap by variation with the width and edge structure that is armchair, zigzag or the combination of both edges. This review covers the recent progress in bottom‐up approaches based on the surface‐catalyzed assembly of molecular precursors and tuning of the electronic properties of GNRs by fabricating atomically precise GNRs of different widths, various edge structures as well as doped structures. In addition, this review also indicates the challenges ahead and possible promising ways to finely tune the electronic structures of GNRs through slight modifications of the molecular configurations of the precursors.

Molecular Bridge Engineering for Tuning Quantum Electronic Transport and Anisotropy in Nanoporous Graphene

“…At the nanoscale, even the most basic quantum size effect, the induction of semiconducting gaps by electron confinement, requires ultimate precision. The case of graphene is a dramatic example where deviations of a single atom in width can induce dramatic variations of the gap of up to a factor of 4. , As a consequence, local defects or variations in width can severely disrupt electron transport properties in nanoscale graphene nanoribbons (GNRs). , Fortunately, the atomic engineering of quantum phenomena in graphene-based nanomaterials started to be a reality a decade ago with the emergence of the bottom-up on-surface synthesis (OSS). − In addition to producing atomically precise homogeneous 1D nanostructures, OSS-based methods can also introduce heteroatoms, , heterojunctions, , or hybrid components , in the structure with the same precision, allowing for a precise engineering of the electronic properties.…”

Band structure modulation by methoxy-functionalization of graphene nanoribbons

“…Thus, considerable efforts have been dedicated to the synthesis of various types of GNRs and elucidation of their structure-property relationships. 2,19 GNRs with different edge structures, including armchair, zigzag, cove, and fjord edges, have thus far been synthesized. The role of the GNR width on bandgaps of armchair GNRs and localized edge states of zigzag GNRs have been demonstrated.…”

Fjord-Edge Graphene Nanoribbons with Site-Specific Nitrogen Substitution

“…The electronic properties of GNRs can be exquisitely tuned by modification of their width, backbone, and edge structure. 1,7,8,9,10 In the last decade, both on-surface and in-solution bottom-up syntheses have achieved precise structural control over these benchmarks. 11,12,13,14,15 Early bottom-up syntheses have focused on GNRs with armchair 16,17,18,19 or zigzag 20 edges.…”

“…Graphene nanoribbons (GNRs) are expected to usher in the ultimate nanosizing of electronics − and sensors , for next generation devices. The electronic properties of GNRs can be exquisitely tuned by modification of their width, backbone, and edge structure. ,− In the past decade, both on-surface and in-solution bottom-up syntheses have achieved precise structural control over these benchmarks. − Early bottom-up syntheses have focused on GNRs with armchair − or zigzag edges. More recently, intricate edge or interior configurations, such as chevron, ,− cove, − fjord, or holey, − have been obtained.…”