In this talk I will describe my recent work on single molecule transport modelling. I will first address the role of metal-molecule chemical linkers and will focus on highly-conducting Au-C links. These covalent Au-C bonds between the electrodes and the molecular backbone result in conductance that is much higher than with other linkers [1] and result in near-resonant transport [2]. Theory reveals the good electronic coupling in Au?C links, which have near ideal contact resistance.

I will also address quantum interference effects in single molecule transport. I will describe the flow of current through molecules that have two backbones bonded in parallel to the electrodes. The calculated and measured conductance of these double-backbone molecules can be more than twice (e.g. ~3×) that of their single-backbone counterparts due to constructive quantum interference [3].

References:

[1] Z-L Cheng, R. Skouta, H. Vázquez, J. Widawsky, S. Schneebeli, M.S. Hybertsen, R.Breslow and L.Venkataraman, 'In situ formation of highly conducting covalent Au-C contacts for single-molecule junctions', Nature Nanotechnology 6 353 (2011).

[2] W. Chen, J.R. Widawsky, H. Vázquez, S. Schneebeli, M.S. Hybertsen, R. Breslow and L. Venkataraman, 'Highly Conducting pi-Conjugated Molecular Junctions Covalently Bonded to Gold Electrodes', J. Am. Chem. Soc. 133 17160 (2011).

[3] H. Vázquez, R. Skouta, S. Schneebeli, M. Kamenetska, R.Breslow, L. Venkataraman and M.S. Hybertsen, 'Probing the Conductance Superposition Law in Single Molecule Circuits with Parallel Paths', Nature Nanotechnology 7 663 (2012).