Berlin 2005 – scientific programme
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O: Oberflächenphysik
O 53: Organische Dünnschichten V
O 53.4: Talk
Wednesday, March 9, 2005, 11:30–11:45, TU EB420
Crystal Face Resolved Oxidation of Pentacene with Ozone — •S. Rentenberger1, H. Weiss2, A. Vollmer3, J. Niemax4, J. Pflaum4, I. Salzmann5, J. P. Rabe5, and N. Koch5 — 1TU-Graz, Institut f. Festkörperphysik, A-8010 Graz, Austria — 2Universität Magdeburg, Lehrstuhl f. Physikalische Chemie, D-39106 Magdeburg — 3BESSY GmbH., D-12489 Berlin — 4Universität Stuttgart, 3. Physikalisches Institut, D-70550 Stuttgart — 5Humboldt-Universität zu Berlin, Institut f. Physik, D-12489 Berlin
While the oxidation of pentacene by molecular oxygen proceeds very slowly, ozone (produced by illumination with ultraviolet light) leads to a rapid oxidation of this prototypical conjugated organic molecule, successfully used in flexible thin film transistors. We have studied the ozone-induced oxidation kinetics of pentacene thin films by infrared absorption spectroscopy in transmittance and reflection, and the accompanied evolution of the film morphology by atomic force microscopy. In order to selectively probe individual pentacene crystal faces, thin films were grown on silicon oxide [exposing the (ab) plane] and on highly oriented pyrolytic graphite [exposing the (bc) plane]. We find in both cases substantial loss of pentacene mass-thickness, indicating that ozone produces highly volatile reaction products, however, on a faster time scale for films grown on graphite.