Date
2021
Abstract
We present an efficient strategy to modulate tunnelling in molecular junctions by changing the tunnelling decay coefficient, β, by terminal-atom substitution which avoids altering the molecular backbone. By varying X = H, F, Cl, Br, I in junctions with S(CH2)(10-18)X, current densities (J) increase >4 orders of magnitude, creating molecular conductors via reduction of β from 0.75 to 0.25 Å−1. Impedance measurements show tripled dielectric constants (εr) with X = I, reduced HOMO-LUMO gaps and tunnelling-barrier heights, and 5-times reduced contact resistance. These effects alone cannot explain the large change in β. Density functional theory shows highly localized, X-dependent potential drops at the S(CH2)nX// electrode interface that modifies the tunnelling barrier shape. Commonly-used tunnelling models neglect localized potential drops and changes in εr.
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Description
peer-reviewed
Publisher
Nature Publishing Group
Citation
Nature Communications;12, 3432
Collections
Physics
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Thompson_2021_Single.pdf
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Keywords
tunnelling, electrode
ULRR Identifiers
https://hdl.handle.net/10344/10324
 https://doi.org/10.34961/10049
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Funding Information
Ministry of Education
Sustainable Development Goals
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