Graphene-Contacted Single Molecular Junctions with Conjugated Molecular Wires

Tao, Shuhui; Zhang, Qian; He, Chun‐Hui; Lin, Xinhua; Xie, Ruo‐Chen; Zhao, Cezhou; Zhao, Chun; Dappe, Yannick J.; Nichols, Richard J.; Yang, Li

doi:10.1021/acsanm.8b01379

Cited by 15 publications

(21 citation statements)

References 33 publications

(67 reference statements)

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“…Therefore, hybrid Au-graphene and standard Au-Au molecular junctions have been studied through I(s) measurements and DFT calculations, with polyphenylenes, using thiol and amine anchoring groups, as a direct comparison with alkane-based molecular junctions [50].…”

Section: Importance Of the Molecular Backbone: Conjugated Molecular Wmentioning

confidence: 99%

Attenuation Factors in Molecular Electronics: Some Theoretical Concepts

Dappe

2020

Applied Sciences

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Understanding the electronic transport mechanisms in molecular junctions is of paramount importance to design molecular devices and circuits. In particular, the role of the different junction components contributing to the current decay—namely the attenuation factor—is yet to be clarified. In this short review, we discuss the main theoretical approaches to tackle this question in the non-resonant tunneling regime. We illustrate our purpose through standard symmetric junctions and through recent studies on hybrid molecular junctions using graphene electrodes. In each case, we highlight the contribution from the anchoring groups, the molecular backbone and the electrodes, respectively. In this respect, we consider different anchoring groups and asymmetric junctions. In light of these results, we discuss some perspectives to describe accurately the attenuation factors in molecular electronics.

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Section: Importance Of the Molecular Backbone: Conjugated Molecular Wmentioning

confidence: 99%

Attenuation Factors in Molecular Electronics: Some Theoretical Concepts

Dappe

2020

Applied Sciences

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“…A number of chemical strategies have been proposed to increase the junction stability, such as developing new anchoring groups for improved molecular binding [ 2–6 ] or increasing the molecular rigidity to reduce conformational changes. [ 7–8 ] Other examples include using new electrode materials, such as graphene [ 9–10 ] and silicon, [ 11–13 ] to build molecular junctions and enhance the junction lifetime via strong covalent CC and SiC bonds. However, no work has been reported to engineer the metal electrode tip, specifically the mostly used gold electrode, for improving the molecular junction stability.…”

Section: Introductionmentioning

confidence: 99%

Developing Longer‐Lived Single Molecule Junctions with a Functional Flexible Electrode

Huang

Zhang

et al. 2021

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Creating single‐molecule junctions with a long‐lived lifetime at room temperature is an open challenge. Finding simple and efficient approaches to increase the durability of single‐molecule junction is also of practical value in molecular electronics. Here it is shown that a flexible gold‐coated nanopipette electrode can be utilized in scanning tunneling microscope (STM) break‐junction measurements to efficiently enhance the stability of molecular junctions by comparing with the measurements using conventional solid gold probes. The stabilizing effect of the flexible electrode displays anchor group dependence, which increases with the binding energy between the anchor group and gold. An empirical model is proposed and shows that the flexible electrode could promote stable binding geometries at the gold‐molecule interface and slow down the junction breakage caused by the external perturbations, thereby extending the junction lifetime. Finally, it is demonstrated for the first time that the internal conduit of the flexible STM tip can be utilized for the controlled molecule delivery and molecular junction formation.

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“…The junctions with high stability are desirable because they can provide unique opportunities to explore the dynamics, kinetics and mechanisms of intermolecular interactions and chemical reactions − and to study the molecular-scale switches or diodes. − To improve the stability of junctions formed by STM means, an intuitive approach is to further improve the mechanical isolation of the STM system, though it is not an easy task practically. Instead, different chemical strategies have been extensively explored, such as increasing the molecular rigidity , or improving the binding between molecule and gold electrode. − In recent years, marvel chemical strategies are exploited to graft molecules onto graphite/graphene − or silicon surfaces. − These new molecular substrates avoid the high mobility of surface atoms (as in the case of gold electrodes) and significantly enhance the junction lifetime via strong covalent C–C or Si–C bonds.…”

Section: Introductionmentioning

confidence: 99%

Long-Lived Gold Single-Atom Junctions Formed by a Flexible Probe for Scanning Tunneling Microscopy Applications

Wang

Chen

et al. 2020

ACS Appl. Nano Mater.

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Flexible probes have shown promise in improving resolution and sensitivity in various scanning probe microscopy based imaging and spectroscopy techniques. However, it has not been utilized in scanning tunneling microscopy (STM) based break-junction (BJ) and fixed-junction (FJ) techniques. In this report, flexible STM tips are facilely fabricated by using goldcoated quartz nanopipettes. The feasibility of using conductive nanopipettes as STM tips is demonstrated by using the STM BJ technique to repeatedly form stable gold quantum point contacts and reliably measure their conductance at an ambient condition. These nanopipette tips are surprisingly durable in the measurements. The junction formation rate and the lifetime of the formed gold atomic junctions are found to be greatly improved using flexible tips. In addition, the most probable lifetime of single-atom junctions formed by the STM FJ method reaches the natural bond lifetime. Thermally activated gold atom relaxations near the banks of the long-lived single-atom contacts are clearly revealed, permitting the insightful study of the mechanical and electrical properties of single gold atoms or atomic-chain structures. In contrast to the conventional solid metal probes, the flexible probes show significant advantages in creating and stabilizing the single-atom junctions, providing exciting opportunities for STM based techniques, molecular electronics, and biosensors.

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Graphene-Contacted Single Molecular Junctions with Conjugated Molecular Wires

Cited by 15 publications

References 33 publications

Attenuation Factors in Molecular Electronics: Some Theoretical Concepts

Attenuation Factors in Molecular Electronics: Some Theoretical Concepts

Developing Longer‐Lived Single Molecule Junctions with a Functional Flexible Electrode

Long-Lived Gold Single-Atom Junctions Formed by a Flexible Probe for Scanning Tunneling Microscopy Applications

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