Regensburg 2010 – scientific programme
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DS: Fachverband Dünne Schichten
DS 44: Organic Thin Films I
DS 44.4: Talk
Friday, March 26, 2010, 11:00–11:15, H8
Coupling effects in heterostructures of Pentacene and perfluorinated Pentacene studied by optical spectroscopy — •Katharina Broch1, Ute Heinemeyer1, Alexander Hinderhofer1, Falk Anger1,2, Oriol Ossó2, Reinhard Scholz3, Alexander Gerlach1, and Frank Schreiber1 — 1Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen — 2MATGAS 2000 AIE, Campus de la UAB, 08193 Bellaterra — 3Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching
Heterostructures of organic semiconductors gain increasing interest in the last years because of their potential applications in organic electronics. To optimize those devices the understanding of the intermolecular coupling is crucial. Therefore, we investigate the optical absorption spectra of heterostructures and possible differences to the spectra of their single components. The combination of pentacene (PEN) with perfluorinated pentacene (PFP) is promising due to their similar geometric structure which can give rise to coevaporated films with a significant level of intermixing and accordingly an efficient intermolecular coupling. Indeed, performing in-situ-measurements with differential reflectance spectroscopy and spectroscopic ellipsometry we find features in the absorption spectra of mixed films that cannot be explained by a linear combination of the single film spectra. In the energy range between 1.4 eV and 2.4 eV spectra of PFP and PEN single and coevaporated films with different mixing ratios are compared and possible theoretical scenarios for coupling effects are discussed.