Regensburg 2007 – scientific programme
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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices
SYOE 8: Poster Session SYOE
SYOE 8.46: Poster
Tuesday, March 27, 2007, 18:00–20:00, Poster B
Optical Properties of Pentacene and Tetracene Thin-Films and Single Crystals — •Daniel Faltermeier1, Bruno Gompf1, Martin Dressel1, Ashutosh Tripathi2, and Jens Pflaum2 — 11.Physikalisches Institut, Universität Stuttgart, D-70550 Stuttgart — 23.Physikalisches Institut, Universität Stuttgart, D-70550 Stuttgart
Pentacene and tetracene are among the most promising organic semiconductors for future device applications due to their high hole mobilities at room temperature. But unlike their electrical properties, their optical behaviour is not well characterized and even the fundamental optical constants and their spatial anisotropy are not investigated to a sufficient degree. We present a systematic study by spectroscopic ellipsometry, AFM and x-ray diffraction on purified and highly ordered pentacene and tetracene films prepared under different conditions on Si/Si02. The optical data are compared with measurements on single crystals grown by gas-phase sublimation technique. The results clearly show the influence of different structural polymorphs and of photo-oxidation processes on the optical properties. By comparison with the respective quinone-derivatives of pentacene and tetracene the reaction products can be identified by their optical response. Additionally the optical and structural results are correlated to temperature dependent mobility measurements.