Low variability of single-molecule conductance assisted by bulky metal-molecule contacts

R.R. Ferradás, Marques Marqués-González, H.M. Osorio, J. Ferrer, P. Cea, D.C. Milan, A. Vezzoli, S.J. Higgins, R.J. Nichols, Paul Low, V.M. García-Suárez, S. Martín

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

© The Royal Society of Chemistry 2016. A detailed study of the trimethylsilylethynyl moiety, -CCSiMe3 (TMSE), as an anchoring group in metalmoleculemetal junctions, using a combination of experiment and density functional theory is presented. It is shown that the TMSE anchoring group provides improved control over the molecule-substrate arrangement within metalmoleculemetal junctions, with the steric bulk of the methyl groups limiting the number of highly transmissive binding sites at the electrode surface, resulting in a single sharp peak in the conductance histograms recorded by both the in situ break junction and I(s) STM techniques. As a consequence of the low accessibility of the TMSE group to surface binding configurations of measurable conductance, only about 10% of gold break junction formation cycles result in the clear formation of molecular junctions in the experimental histograms. The DFT-computed transmission characteristics of junctions formed from the TMSE-contacted oligo(phenylene)ethynylene (OPE)-based molecules described here are dominated by tunneling effects through the highest-occupied molecular orbitals (HOMOs). This gives rise to similar conductance characteristics in these TMSE-contacted systems as found in low conductance-type junctions based on comparably structured OPE-derivatives with amine-contacts that also conduct through HOMO-based channels.
Original languageEnglish
Pages (from-to)75111-75121
Number of pages11
JournalRSC Advances
Volume6
Issue number79
DOIs
Publication statusPublished - 8 Apr 2016

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