Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 52: Metal substrates: Adsorption of organic / bio molecules VII
O 52.16: Vortrag
Donnerstag, 26. März 2009, 18:45–19:00, SCH A118
High-resolution ARUPS study of thin CuPc films on noble-metal (111) surfaces — •Mario Kochler1, Johannes Ziroff1, Frank Forster1, Hatice Karacuban2, and Friedrich Reinert1,3 — 1Universität Würzburg, Experimentelle Physik II, Am Hubland, D-97074 Würzburg, Germany — 2Universität Duisburg Essen, Fachbereich Physik, D-47057 Duisburg, Germany — 3Forschungszentrum Karlsruhe, Gemeinschaftslabor für Nanoanalytik, D-76021 Karlsruhe, Germany
The large π-conjugated organic molecule copper phthalocyanine (CuPc) is widely applied in the promising field of organic electronics, for instance as donor material in solar cells. For these applications the electronic structure of the organo-metallic interface is of particular interest. We present high-resolution ARUPS data of epitaxial CuPc films on Au, Ag and Cu (111). The valence band features, i.e. the highest occupied molecular orbital (HOMO), the former lowest unoccupied molecular orbital (F-LUMO) and a sharp resonance right at the Fermi level, are specific for each substrate. The differences in the electronic structure are a result of the increasing interaction strength between the molecules and the substrate, ranging from physisorption on Au to strong chemisorption on Cu. We correlate the coverage dependent change of the HOMO binding energy to the individual adsorption strength. The intermediate bonding strength on Ag (111) causes a partially filled F-LUMO that gives rise to the sharp resonance at the Fermi level. We will discuss these features on the background of the different growth modes of CuPc on noble metal surfaces.