Regensburg 2007 – scientific programme

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DS: Fachverband Dünne Schichten

DS 7: Organic Film Aging (SYOE 3)

DS 7.3: Talk

Monday, March 26, 2007, 18:30–18:45, H32

Real-time observation of oxidation and photo-oxidation of rubrene thin films by spectroscopic ellipsometry — •Milan Kytka^1,2, Alexander Gerlach¹, Frank Schreiber¹, and Jaro Kováč² — ¹Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany — ²Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovičova 3, 812 19 Bratislava, Slovak Republic

We follow in real-time and under controled conditions the oxidation of the organic semiconductor rubrene grown on SiO₂ using spectroscopic ellipsometry. We derive the complex dielectric function ε₁ + iε₂ for pristine and oxidized rubrene showing that the oxidation is accompanied by a significant change of the optical properties, namely the absorption. We observe that photo-oxidation of rubrene is much faster than oxidation without illumination.

By following different absorption bands (around 2.5 eV and 4.0 eV for pristine rubrene and around 4.9 eV for oxidized rubrene) we infer that the photo-oxidation of these films involves non-Fickian diffusion mechanisms.