Regensburg 2007 – wissenschaftliches Programm
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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices
SYOE 8: Poster Session SYOE
SYOE 8.102: Poster
Dienstag, 27. März 2007, 18:00–20:00, Poster B
Effects of capping on the thermal and long-term stability of organic thin film transistors — •Stephan Meyer1, Stefan Sellner2, Gerhard Ulbricht2, Frank Schreiber2, Helmut Dosch2, Matthias Fischer1, Bruno Gompf1, and Jens Pflaum1 — 1Physikalische Institute, Universität Stuttgart — 2MPI Stuttgart
The thermal robustness of organic semiconducting layers and their long-term performance determine their applicability in organic electronics. To address these issues we have performed studies on pentacene thin film transistors (TFTs) with and without encapsulation. The capping layer is realized by a ∼ 100nm thick sputtered layer of aluminum oxide or by a ∼3µm polymer layer of poly-para-xylylene. A field-effect can be demonstrated for both capping materials up to temperatures of ∼ 140∘C, which is about 50∘C above the desorption point of uncapped pentacene thin films on SiO2. A complex behavior of the temperature dependent hole mobility can be deduced from the TFT characteristics, indicating that the device operation at elevated temperatures is predominantly limited by the transistor structure and not by the organic material. Comparative studies on the long-term stability of the electronic TFT properties will be discussed for both capping materials.The microscopic mechanisms resulting in the structural breakdown of the pentacene layer have been analyzed by thermal desorption spectroscopy and temperature dependent x-ray diffraction. The thermally induced breakdown will be discussed also for other materials such as diindenoperylene [1].
S. Sellner, et al., J. Mater. Res. 21, 455 (2006).