Electrical properties and mechanical stability of anchoring groups for single-molecule electronics.

Riccardo Frisenda,Herre S J Van Der Zant,Ferdinand C Grozema,Mickael L Perrin,Elena Galán,Simge Tarkuç,Rienk Eelkema

doi:10.3762/bjnano.6.159

Riccardo Frisenda, Herre S J Van Der Zant + Show 5 more

Open Access

https://doi.org/10.3762/bjnano.6.159

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Abstract

We report on an experimental investigation of transport through single molecules, trapped between two gold nano-electrodes fabricated with the mechanically controlled break junction (MCBJ) technique. The four molecules studied share the same core structure, namely oligo(phenylene ethynylene) (OPE3), while having different aurophilic anchoring groups: thiol (SAc), methyl sulfide (SMe), pyridyl (Py) and amine (NH2). The focus of this paper is on the combined characterization of the electrical and mechanical properties determined by the anchoring groups. From conductance histograms we find that thiol anchored molecules provide the highest conductance; a single-level model fit to current–voltage characteristics suggests that SAc groups exhibit a higher electronic coupling to the electrodes, together with better level alignment than the other three groups. An analysis of the mechanical stability, recording the lifetime in a self-breaking method, shows that Py and SAc yield the most stable junctions while SMe form short-lived junctions. Density functional theory combined with non-equlibrium Green’s function calculations help in elucidating the experimental findings.

Highlights

Molecular-scale electronics is a field that in recent years experienced an enormous growth thanks to the development of reliable techniques to trap and electrically contact single molecules [1,2,3]
We have compared four different aurophilic anchoring groups widely used in molecular-scale electronics and investigated their influence, on the electrical and mechanical properties of single-molecule junctions, formed with mechanically controlled break junction (MCBJ) gold nano-electrodes
A single-level model analysis of the I–Vs shows that SAc groups give the best electronic coupling and level alignment to the gold nano-electrodes

Summary

Introduction

Molecular-scale electronics is a field that in recent years experienced an enormous growth thanks to the development of reliable techniques to trap and electrically contact single molecules [1,2,3]. A statistical analysis of the I–Vs with a fit to a single-level model allows to quantify the electronic coupling between the various molecules and the electrodes and the injection barrier [33].

Results

Conclusion