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 8.100: Poster

Dienstag, 27. März 2007, 18:00–20:00, Poster B

Photodegradation of P3HT thin films under various ambient conditions — •Raphael Gutbrod¹, Hans-Joachim Egelhaaf^1,2, Heiko Peisert¹, and Thomas Chassé¹ — ¹University of Tübingen, IPTC, Auf der Morgenstelle 8, D-72076 Tübingen, Germany — ²Christian-Doppler-Lab for Surface-Optical Methods, Konarka Austria GmbH, Altenberger Str. 69, A-4040 Linz, Austria

Poly-3-hexylthiophene (P3HT) is one of the most promising semiconducting materials for applications in organic field effect transistors (OFET). To improve the device performance, it is necessary to control the film morphology, its structure and the interface between insulator and active layer. An important parameter in terms of commercial use is the device lifetime. It is known, that photodegradation of P3HT in air reduces its semiconducting properties and thus the lifetime. Therefore, exact understanding of this process is important for further device optimization. The photooxidation of spin-coated P3HT thin films under various ambient conditions was studied using UV/Vis spectroscopy and the resulting oxidation products were characterized by X-ray photoelectron spectroscopy (XPS). We observed an increased oxidation time in presence of water. Furthermore, an influence of different substrates on the phenomenon was noticed. An insulator as top coating layer increases the oxidation time of the P3HT thin film as it works as diffusion barrier for oxygen and water. To understand the process on a molecular point of view, a possible reaction mechanism for the photodegradation is discussed.