Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 35: TR: Nanoelectronics III: Molecular Electronics 1
TT 35.9: Vortrag
Donnerstag, 25. März 2010, 16:15–16:30, H21
Single-molecule Junctions with C60 Fullerene-based Anchoring Groups — •Christian Seiler1, Alexei Bagrets2, Velimir Meded2, and Ferdinand Evers1,2 — 1Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe, Germany — 2Institut für Nanotechnologie, Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany
We investigate electronic structure and recently measured [1] ballistic transport properties of the 1,4-bis(fullero[c]pyrrolidin-1-yl)benzene (BDC60) molecule with gold contacts using Density Functional Theory and the Landauer-Büttiker formalism. We study the potential of C60 fullerenes as anchoring groups from a theoretical point of view. Because the high symmetry of C60 leads to a large HOMO-LUMO gap, it behaves like a band insulator, casting doubts on its suitability as an anchoring group. We analyze the effect of symmetry breaking in the presence of electrodes and discover that the electronic level splitting of C60 is small, not mitigating the issue. Moreover, electronic structure calculations of BDC60 reveal that its current-carrying HOMO is a state originating from the internal benzene ring with an energy in the gap of the anchoring C60. Its hybridization is low which we attribute to the π-systems of C60 and the internal benzene ring being nearly orthogonal. We conclude that this creates an additional tunneling barrier which is in agreement with the low conductance values found in [1].
[1] Christian A. Martin et al., JACS, 130(40):13198-13199, 2008