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Planar aromatic anchors control the electrical conductance of gold|molecule|graphene junctions

O’Driscoll, Luke J.; Jay, Michael; Robinson, Benjamin J.; Sadeghi, Hatef; Wang, Xintai; Penhale-Jones, Becky; Bryce, Martin R.; Lambert, Colin J.

Planar aromatic anchors control the electrical conductance of gold|molecule|graphene junctions Thumbnail


Authors

Michael Jay

Benjamin J. Robinson

Hatef Sadeghi

Xintai Wang

Becky Penhale-Jones

Colin J. Lambert



Abstract

The synthesis of a family of alkanethiol molecules with planar aromatic head groups, designed to anchor molecules effectively to graphene electrodes, is reported. Characterisation of self-assembled monolayers of these molecules on a gold surface via conductive atomic force microscopy shows that when an aromatic head group is present, the conductance Ggraphene obtained using a graphene coated probe is higher than the conductance GPt obtained using a platinum (Pt) probe. For Pt probe and graphene probe junctions, the tunnelling decay constant of benzyl ether derivatives with an alkanethiol molecular backbone is determined as 𝛽 = 5.6 nm-1 and 3.5 nm-1, respectively. The conductance ratio Ggraphene/GPt increases as the number of rings present in the aromatic head unit, n, increases. However, as the number of rings increases, the conductance path length increases because the planar head groups lie at an angle to the plane of the electrodes. This means that overall conductance decreases as n increases. Density functional theory-based charge transport calculations support these experimental findings. This study confirms that planar aromatic head groups can function as effective anchoring units for graphene electrodes in large area molecular junctions. However, the results also indicate that the size and geometry of these head groups must be considered in order to produce effective molecular designs.

Citation

O’Driscoll, L. J., Jay, M., Robinson, B. J., Sadeghi, H., Wang, X., Penhale-Jones, B., …Lambert, C. J. (2023). Planar aromatic anchors control the electrical conductance of gold|molecule|graphene junctions. Nanoscale Advances, 5(8), 2299-2306. https://doi.org/10.1039/d2na00873d

Journal Article Type Article
Acceptance Date Mar 8, 2023
Online Publication Date Mar 27, 2023
Publication Date Apr 21, 2023
Deposit Date Mar 14, 2023
Publicly Available Date May 30, 2023
Journal Nanoscale Advances
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 5
Issue 8
Pages 2299-2306
DOI https://doi.org/10.1039/d2na00873d

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