The use of graphene in electronic devices requires a band gap, which can be achieved by creating nanostructures such as nanoribbons. A wide variety atomically precise nanoribbons prepared through on-surface synthesis, bringing the concept nanoribbon electronics closer to reality. For future applications it is beneficial integrate contacts and more functionality directly into single ribbons using heterostructures. Here, we synthesis approach fabricate metal-semiconductor junction tunnel...

On-surface synthesis with molecular precursors has emerged as the de facto route to atomically well-defined graphene nanoribbons (GNRs) controlled zigzag and armchair edges. On Au(111) Ag(111) surfaces, prototypical precursor 10,10′-dibromo-9,9′-bianthryl (DBBA) polymerizes through an Ullmann reaction form straight GNRs However, on Cu(111), irrespective of bianthryl (dibromo-, dichloro-, or halogen-free bianthryl), is inactive, instead, identical chiral are formed. Using resolved noncontact...

The design of a spin imbalance within the crystallographic unit cell bottom-up engineered 1D graphene nanoribbons (GNRs) gives rise to nonzero magnetic moments each cell. Here, we demonstrate assembly and spectroscopic characterization one-dimensional Kondo chain formed by chevron-type GNR (cGNR) physisorbed on Au(111). Substitutional nitrogen core doping introduces pair low-lying occupied states per monomer semiconducting gap cGNRs. Charging resulting from interaction with gold substrate...

The covalent interaction of N-heterocyclic carbenes (NHCs) with transition metal atoms gives rise to distinctive frontier molecular orbitals (FMOs). These emergent electronic states have spurred the widespread adoption NHC ligands in chemical catalysis and functional materials. Although formation carbene-metal complexes self-assembled monolayers on surfaces has been explored, design structure characterization extended low-dimensional NHC-metal lattices remains elusive. Here we demonstrate a...

Substitutional heteroatom doping of bottom-up engineered 1D graphene nanoribbons (GNRs) is a versatile tool for realizing low-dimensional functional materials nanoelectronics and sensing. Previous efforts have largely relied on replacing C-H groups lining the edges GNRs with trigonal planar N atoms. This type atomically precise doping, however, only results in modest realignment valence band (VB) conduction (CB) energies. Here, we report design, synthesis, spectroscopic characterization...

The integration of low-energy states into bottom-up engineered graphene nanoribbons (GNRs) is a robust strategy for realizing materials with tailored electronic band structure nanoelectronics. Low-energy zero-modes (ZMs) can be introduced nanographenes (NGs) by creating an imbalance between the two sublattices graphene. This phenomenon exemplified family [n]triangulenes (n ∈ N). Here, we demonstrate synthesis [3]triangulene-GNRs, regioregular one-dimensional (1D) chain [3]triangulenes linked...

We have studied the incommensurate moir\'e structure of epitaxial graphene grown on iridium(111) by dynamic low-energy electron diffraction [LEED $I$($V$)] and noncontact atomic force microscopy (AFM) with a CO-terminated tip. Our LEED $I$($V$) results yield average positions all atoms in surface unit cell are qualitative agreement obtained from density functional theory. The AFM experiments reveal local variations structure: corrugation varies smoothly over several cells between 42 56 pm....

Bottom-up graphene nanoribbons (GNRs) have recently been shown to host nontrivial topological phases. Here, we report the fabrication and characterization of deterministic GNR quantum dots whose orbital character is defined by zero-mode states arising from interfaces. Topological control was achieved through synthesis on-surface assembly three distinct molecular precursors designed exhibit structurally derived electronic states. Using a combination low-temperature scanning tunneling...

The scope of graphene nanoribbon (GNR) structures accessible through bottom-up approaches is defined by the intrinsic limitations either all-on-surface or all-solution-based synthesis. Here, we report a hybrid synthesis GNRs based on Matrix-Assisted Direct (MAD) transfer technique that successfully leverages technical advantages inherent to both solution-based and on-surface while sidestepping their drawbacks. Critical structural parameters tightly controlled in polymerization reactions can...

Nitrogen core-doping of graphene nanoribbons (GNRs) allows trigonal planar carbon atoms along the backbone GNRs to be substituted by higher-valency nitrogen atoms. The excess valence electrons are injected into π-orbital system GNR, thereby changing not only its electronic occupation but also topological properties. We have observed this change synthesizing dilute core-doped armchair with a width five (N2-5-AGNRs). incorporation pairs results in emergence boundary states at interface between...

Abstract The Ullmann coupling has been used extensively as a synthetic tool for the formation of C−C bonds on surfaces. Thus far, most syntheses made use aryl bromides or iodides. We investigated applicability an chloride in bottom‐up assembly graphene nanoribbons. Specifically, reactions 10,10′‐dichloro‐9,9′‐bianthryl (DCBA) Au(111) were studied. Using atomic resolution non‐contact AFM, structure various products and intermediates resolved, allowing us to reveal important role geometry...

While enormous progress has been achieved in synthesizing atomically precise graphene nanoribbons (GNRs), the preparation of GNRs with a fully predetermined length and monomer sequence remains an unmet challenge. Here, we report fabrication method that provides access to structurally diverse monodisperse "designer" through utilization iterative synthesis strategy, which single is incorporated into oligomer chain during each chemical cycle. Surface-assisted cyclodehydrogenation subsequently...

With the advent of atomically precise synthesis and consequent tailoring their electronic properties, graphene nanoribbons (GNRs) have emerged as promising building blocks for nanoelectronics. Before being applied such, it is imperative that charge transport properties are investigated. Recently, formation a molecular junction through controlled attachment to probe scanning tunneling microscope (STM) subsequent lifting allowed first conductance measurements. Drawbacks perturbation intrinsic...

Abstract Nanoporous graphene (NPG) can exhibit a uniform electronic band gap and rationally‐engineered emergent properties, promising for devices such as field‐effect transistors (FETs), when synthesized with atomic precision. Bottom‐up, on‐surface synthetic approaches developed nanoribbons (GNRs) now provide the necessary precision in NPG formation to access these desirable properties. However, potential of bottom‐up has remained largely unexplored date. Here, FETs based on chevron‐type...

Semiconducting graphene nanoribbons (GNRs) are envisioned to play an important role in future electronics. This requires the GNRs be placed on a surface where they may become strained. Theory predicts that axial strain, i.e. in-plane bending of GNR, will cause change band gap GNR. negatively affect device performance. Using tip scanning tunneling microscope we controllably bent and buckled atomically well-defined narrow armchair GNR subsequently probed changes local density states. These...

The structure of graphene nanoribbons crucially affects their electronic properties and transport. Here, the authors elucidate transport in various nanoribbon heterostructures via measurements with scanning tunneling microscope theoretical modeling based on an atomistic mean-field Hubbard model. This reveals intricate interplay between transport, topology, eigenstate localization, magnetism, emergent negative differential resistance.

Abstract Carbon‐based quantum dots (QDs) enable flexible manipulation of electronic behavior at the nanoscale, but controlling their magnetic properties requires atomically precise structural control. While magnetism is observed in organic molecules and graphene nanoribbons (GNRs), GNR precursors enabling bottom‐up fabrication QDs with various spin ground states have not yet been reported. Here development a new precursor that results QD structures embedded semiconducting GNRs Inserting one...

If organic molecules are to be used as the active component in devices, self-assembly represents most attractive route control geometric structure and therefore part of device performance. High-resolution scanning tunneling microscopy measurement combined with density functional theory Monte Carlo calculations study stability self-assemblies bonding motifs spanning (nearly) entire range intermolecular interaction strengths. Our atomistic model reproduces experimentally observed crystal...

On-surface synthesis has emerged in the last decade as a method to create graphene nanoribbons (GNRs) with atomic precision. The underlying premise of this bottom-up strategy is that precursor molecules undergo well-defined sequence inter- and intramolecular reactions, leading formation single product. As such, structure GNR encoded precursors. However, recent examples have shown not only molecule, but also coinage metal surface on which reaction takes place, plays decisive role dictating...

The incorporation of nonhexagonal rings into graphene nanoribbons (GNRs) is an effective strategy for engineering localized electronic states, bandgaps, and magnetic properties. Here, we demonstrate the successful synthesis having four-membered ring (cyclobutadienoid) linkages by using on-surface approach involving direct contact transfer coronene-type precursors followed thermally assisted [2 + 2] cycloaddition. resulting coronene-cyclobutadienoid feature a narrow 600-meV bandgap novel...

The low-energy electronic structure of nanographenes can be tuned through zero-energy π-electron states, typically referred to as zero-modes. Customizable and magnetic structures have been engineered by coupling zero-modes exchange hybridization interactions. Manipulation the energy such however, has not yet received significant attention. We find that attaching a five-membered ring zigzag edge hosting zero-mode perturbs mode turns it into an off-zero mode: localized state with distinctive...

Abstract The Ullmann coupling has been used extensively as a synthetic tool for the formation of C−C bonds on surfaces. Thus far, most syntheses made use aryl bromides or iodides. We investigated applicability an chloride in bottom‐up assembly graphene nanoribbons. Specifically, reactions 10,10′‐dichloro‐9,9′‐bianthryl (DCBA) Au(111) were studied. Using atomic resolution non‐contact AFM, structure various products and intermediates resolved, allowing us to reveal important role geometry...

Graphene nanoribbons (GNRs), when synthesized with atomic precision by bottom–up chemical approaches, possess tunable electronic structure, and high theoretical mobility, conductivity, heat dissipation capabilities, which makes them an excellent candidate for channel material in post-silicon transistors. Despite their immense potential, achieving highly transparent contacts efficient charge transport—which requires proper contact selection a deep understanding of the complex one-dimensional...