Berlin 2008 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 14: Transport: Nanoelectronics III - Molecular Electronics
TT 14.7: Talk
Tuesday, February 26, 2008, 11:00–11:15, H 3010
Length-dependent conductance and thermopower in metal-molecule-metal junctions — •Janne Viljas1,2, Fabian Pauly1, and Juan Carlos Cuevas3,1,2 — 1Institut für Theoretische Festkörperphysik and DFG-Center for Functional Nanostructures, Universität Karlsruhe, D-76128 Karlsruhe — 2Forschungszentrum Karlsruhe, Institut für Nanotechnologie, D-76021 Karlsruhe — 3Departamento de Física Teórica de la Materia Condensada C-V, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
Using a method based on density-functional theory, we investigate the conductance and the thermopower in metal-molecule-metal junctions made of dithiolated oligophenylenes contacted to gold electrodes [1]. We find that while the conductance decays exponentially with increasing molecular length, the thermopower increases linearly in good quantitative agreement with recent experiments [2]. We also analyze how these transport properties can be tuned with methyl side groups. The characteristic substituent effects in our ab-initio calculations are explained using a π-electron tight-binding model, which we have studied in detail.
[1] F. Pauly, J. K. Viljas, and J. C. Cuevas, arXiv:0709.3588.
[2] P. Reddy et al., Science 315, 1568 (2007).