In most computational and experimental studies of charge transport through molecular junctions, noble metals (Au, Pt, Ag, etc.) are used as leads to contact individual molecules. In this work, we study structure and transport properties of graphite/amine terminated oligophenyl/Au molecular junctions, using ab initio calculations employing self energy-corrected density functional theory within a non-equilibrium Green's function formalism. Our finite-bias calculations explain measured conductances quantitatively. Further, we show that such junctions rectify due to the asymmetric coupling to the Au and graphite electrodes, and to the strong energy dependence of the density of states of graphite around Fermi level. Predicted rectification ratios are in quantitative agreement with experiment. Our study would potentially open up a new class of molecular junctions with dissimilar electrodes using graphite and other two dimensional materials. The experimental part of the work is supported by NSF DMR-1122594. The computational part of the work is supported by the Department of Energy. Computational resources are provided by NERSC.

Rectification in molecular junctions with carbon-based electrodes: Theory and experiment

248th National Meeting (2014)

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