Graphene as a Promising Electrode for Low-Current Attenuation in Nonsymmetric Molecular Junctions

Qian Zhang, Longlong Liu, Shuhui Tao, Congyi Wang, Cezhou Zhao, César González, Yannick J. Dappe, Richard J. Nichols, Li Yang*

*Corresponding author for this work

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Abstract

We have measured the single-molecule conductance of 1,n-alkanedithiol molecular bridges (n = 4, 6, 8, 10, 12) on a graphene substrate using scanning tunneling microscopy (STM)-formed electrical junctions. The conductance values of this homologous series ranged from 2.3 nS (n = 12) to 53 nS (n = 4), with a decay constant βn of 0.40 per methylene (CH2) group. This result is explained by a combination of density functional theory (DFT) and Keldysh-Green function calculations. The obtained decay, which is much lower than the one obtained for symmetric gold junctions, is related to the weak coupling at the molecule-graphene interface and the electronic structure of graphene. As a consequence, we show that using graphene nonsymmetric junctions and appropriate anchoring groups may lead to a much-lower decay constant and more-conductive molecular junctions at longer lengths.

Original languageEnglish
Pages (from-to)6534-6540
Number of pages7
JournalNano Letters
Volume16
Issue number10
DOIs
Publication statusPublished - 12 Oct 2016

Keywords

  • Graphene-based electrode
  • alkanedithiol
  • charge transport
  • density functional theory
  • single molecule conductance

Cite this

Zhang, Q., Liu, L., Tao, S., Wang, C., Zhao, C., González, C., Dappe, Y. J., Nichols, R. J., & Yang, L. (2016). Graphene as a Promising Electrode for Low-Current Attenuation in Nonsymmetric Molecular Junctions. Nano Letters, 16(10), 6534-6540. https://doi.org/10.1021/acs.nanolett.6b03180