Regensburg 2016 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 55: Organic Thin Films III
DS 55.3: Vortrag
Freitag, 11. März 2016, 10:00–10:15, H8
Effects of Molecular Orientation in Acceptor-Donor Interfaces between Pentacene and C60 and Diels-Alder Adduct Formation at the Molecular Interface — •Tobias Breuer, Andrea Karthäuser, and Gregor Witte — AG Molekulare Festkörperphysik, Philipps-Universität Marburg
Interfaces between pentacene and Buckminster-Fullerene (C60) have attracted interest due to their application as oligomeric model system for organic solar cells. As the actual device characteristics in such implementations are crucially controlled by the interface structure, detailed investigations of this interface on a molecular level are mandatory. Therefore, we have analyzed the influence of the orientation of the pentacene molecules in highly-ordered crystalline bottom layers on the characteristics of such interfaces. We show that the interface structure is driven by temperature-controlled diffusion of C60 molecules to the pentacene step-edges in the case of uprightly-oriented pentacene. For lying pentacene in the bottom layer, no step-edge decoration is observed and the wetting of the pentacene layer is enhanced. Furthermore, the stability of the interface against intercalation and re-orientation has been analyzed by means of NEXAFS spectroscopy, showing that the orientation of the pentacene molecules at the interface remains unchanged. Instead, we observe strong indication for a chemical modification of the molecular entities by the formation of Diels-Alder adducts between C60 and pentacene, which challenges the interpretation of this model system as chemically inert.