Regensburg 2007 – scientific programme

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DS: Fachverband Dünne Schichten

DS 5: Organic Interfaces (SYOE 1)

DS 5.3: Talk

Monday, March 26, 2007, 15:00–15:15, H32

Molecular Orientation and Adsorption Energies of Pentacene: SiO₂ versus Metals — •Daniel Käfer and Gregor Witte — Physikalische Chemie I, Ruhr-Universität Bochum, 44780 Bochum

Having a high charge carrier mobility, pentacene is still one of the most promising organic semiconductors for the fabrication of organic thin film transistors. Of particular interest is the interaction at the interface with noble metals and SiO₂ substrates since these materials are commonly used in field-effect devices. Because of the high anisotropy of the charge carrier mobility the molecular orientation of pentacene within the first layers of thin films plays a crucial role. Moreover, the subsequent film growth depends largely on this interface structure. By combining NEXAFS and XRD to determine the molecular orientation and crystalline phase with TDS to probe the interaction strength, pentacene films grown on SiO₂, gold and silver surfaces as well as SAM covered Au substrates have been investigated in detail. Distinctly different desorption temperatures were obtained for the various crystalline phases grown on bare metal substrates and for the thin and thick film phases formed on SiO₂ and SAM covered gold.