Berlin 2005 – scientific programme
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O: Oberflächenphysik
O 20: Organische Dünnschichten II
O 20.7: Talk
Saturday, March 5, 2005, 12:15–12:30, TU EB202
Strongly Enhanced Thermal Stability of Crystalline Organic Thin Films Induced by Aluminum Oxide Capping Layers — •S. Sellner1,2, A. Gerlach3, F. Schreiber3, M. Kelsch1, N. Kasper1, H. Dosch1,2, S. Meyer4, J. Pflaum4, M. Fischer5, and B. Gompf5 — 1Max-Planck-Institut für Metallforschung, Stuttgart, Germany — 2Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Germany — 3Physical and Theoretical Chemistry Laboratory, Oxford University, UK — 4III. Physikalisches Institut, Universität Stuttgart, Germany — 5I. Physikalisches Institut, Universität Stuttgart, Germany
We show that the thermal stability of organic semiconductor thin films can be strongly enhanced by capping with an aluminum oxide layer. By thermal desorption spectroscopy and in-situ X-ray diffraction we demonstrat that organic films do not only stay on the substrate, but even remain crystalline up to 270∘C above their desorption point for uncapped films [1]. Different parameters contributing to the stability enhancement and eventual breakdown of the crystalline order of the organic film at elevated temperatures were identified. We argue that this very efficient enhancement of the thermal stability compared to uncapped and also to metal-capped organic layers is related to the low mobility of aluminum oxide and the structurally well-defined as-grown interfaces exhibiting limited interdiffusion. Possible mechanisms for the eventual breakdown at high temperatures will be discussed.
[1] Sellner et al., Adv. Mat. 16 (2004), p. 1750