1. Large negative differential conductance in single-molecule break junctions
- Author
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J.A. Gil, Nicolas Renaud, Riccardo Frisenda, Ferdinand C. Grozema, Johannes S. Seldenthuis, Diana Dulić, Hennie Valkenier, Jan C. Hummelen, Max Koole, J. M. Thijssen, Herre S. J. van der Zant, Mickael L. Perrin, and Stratingh Institute of Chemistry
- Subjects
Biomedical Engineering ,Bioengineering ,02 engineering and technology ,DEVICE ,010402 general chemistry ,01 natural sciences ,Molecular physics ,Negative Differential Conductance ,Single-Molecule ,Break Junctions ,Atomic orbital ,Molecular conductance ,Molecule ,CONTACTS ,General Materials Science ,Molecular orbital ,Electrical and Electronic Engineering ,Physics ,Molecular electronics ,Conductance ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,TRANSPORT ,0104 chemical sciences ,CONFORMATION ,Quantum dot ,Density functional theory ,ORGANIC-MOLECULES ,Atomic physics ,0210 nano-technology ,RESISTANCE - Abstract
Molecular electronics aims at exploiting the internal structure and electronic orbitals of molecules to construct functional building blocks(1). To date, however, the overwhelming majority of experimentally realized single-molecule junctions can be described as single quantum dots, where transport is mainly determined by the alignment of the molecular orbital levels with respect to the Fermi energies of the electrodes(2) and the electronic coupling with those electrodes(3,4). Particularly appealing exceptions include molecules in which two moieties are twisted with respect to each others(5,6) and molecules in which quantum interference effects are possible(7,8). Here, we report the experimental observation of pronounced negative differential conductance in the current-voltage characteristics of a single molecule in break junctions. The molecule of interest consists of two conjugated arms, connected by a non-conjugated segment, resulting in two coupled sites. A voltage applied across the molecule pulls the energy of the sites apart, suppressing resonant transport through the molecule and causing the current to decrease. A generic theoretical model based on a two-site molecular orbital structure captures the experimental findings well, as confirmed by density functional theory with non-equilibrium Green's functions calculations that include the effect of the bias. Our results point towards a conductance mechanism mediated by the intrinsic molecular orbitals alignment of the molecule.
- Published
- 2014