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

doi:10.1021/acs.nanolett.6b03180

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

Research output: Contribution to journal › Article › peer-review

44 Citations (Scopus)

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 β_n 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 language	English
Pages (from-to)	6534-6540
Number of pages	7
Journal	Nano Letters
Volume	16
Issue number	10
DOIs	https://doi.org/10.1021/acs.nanolett.6b03180
Publication status	Published - 12 Oct 2016

Keywords

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

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10.1021/acs.nanolett.6b03180

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title = "Graphene as a Promising Electrode for Low-Current Attenuation in Nonsymmetric Molecular Junctions",

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.",

keywords = "Graphene-based electrode, alkanedithiol, charge transport, density functional theory, single molecule conductance",

author = "Qian Zhang and Longlong Liu and Shuhui Tao and Congyi Wang and Cezhou Zhao and C{\'e}sar Gonz{\'a}lez and Dappe, {Yannick J.} and Nichols, {Richard J.} and Li Yang",

note = "Funding Information: This work was supported by the National Natural Science Foundation of China (NSFC grants 21503169), the Jiangsu Science and Technology program (BK 20140405), Suzhou Industrial Park Initiative Platform Development for Suzhou Municipal Key Lab for New Energy Techniques (RR0140) and the XJTLU Research Development Fund (PGRS-13-01-03 and RDF-14-02-42). Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

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doi = "10.1021/acs.nanolett.6b03180",

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T1 - Graphene as a Promising Electrode for Low-Current Attenuation in Nonsymmetric Molecular Junctions

AU - Zhang, Qian

AU - Liu, Longlong

AU - Tao, Shuhui

AU - Wang, Congyi

AU - Zhao, Cezhou

AU - González, César

AU - Dappe, Yannick J.

AU - Nichols, Richard J.

AU - Yang, Li

N1 - Funding Information: This work was supported by the National Natural Science Foundation of China (NSFC grants 21503169), the Jiangsu Science and Technology program (BK 20140405), Suzhou Industrial Park Initiative Platform Development for Suzhou Municipal Key Lab for New Energy Techniques (RR0140) and the XJTLU Research Development Fund (PGRS-13-01-03 and RDF-14-02-42). Publisher Copyright: © 2016 American Chemical Society.

PY - 2016/10/12

Y1 - 2016/10/12

N2 - 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.

AB - 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.

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KW - single molecule conductance

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

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