Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)
O 35.27: Poster
Dienstag, 12. März 2013, 18:15–21:45, Poster B1
Structural and Electronic Properties of Self-Assembled DCV5T-Me2 Molecules on Au(111): from Sub-Monolayer to Bilayer Coverage — •Zechao Yang1, Martina Corso1,2, Chris Lotze1, Elena Mena-Osteritz3, Peter Bäuerle3, Katharina J. Franke1, and Jose I. Pascual1,2 — 1Institut für Experimentalphysik, Freie Universität Berlin, Germany — 2CIC nanoGune, 20018 Donostia-San Sebastián, Spain — 3Institute of Organic Chemistry II and Advanced Materials, University of Ulm, Germany
The functionality of organic electronic devices importantly depends on the structural and electronic properties of the metal-molecule interface. Here, we investigate the structural and electronic properties of ultra-thin films of substituted oligothiophene molecules on a gold surface using low temperature scanning tunneling microscopy and spectroscopy. The chosen molecule, dicyanovinyl-quinquethiophenes (DCV5T-Me2), is used in organic solar cells. DCV5T-Me2 molecules form either molecular chains, stabilized by intercalated Au atoms, or two-dimensional islands depending on the sub-monolayer coverage. The presence of Au atoms in the chains leads to local modification of their electronic structure: the LUMO of molecules in chains have a low energy unoccupied resonance downshifted due to coordination bonds. In fact, molecules at the chain end shows both the unperturbed state, at the free side, and the down shifted state, at the side in contact with Au atoms with no effect on the other side without coordination bonding. This behavior indicates that one can manipulate molecular orbital alignment within individual molecules by coordination bonding meditation.