Berlin 2008 – scientific programme

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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 5: Poster Session SYSA

SYSA 5.33: Poster

Tuesday, February 26, 2008, 14:30–20:00, Poster A

Temperature dependant resonant photoemission and NEXAFS study of zinc(II)phthalocyanine on poly- and single crystalline gold — •Britt-Elfriede Schuster¹, Indro Biswas¹, Maria Benedetta Casu¹, David Batchelor², Martin Knupfer³, Heiko Peisert¹, and Thomas Chassé¹ — ¹Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen. — ²BESSY GmbH, 12489 Berlin. — ³Leibniz Institute for Solid State and Materials Research Dresden, P.O. Box 270116, 01171 Dresden.

The arrangement and the orientation of organic molecules are crucial for charge transport properties and thus essential for the efficiency of devices based on these materials. Mechanisms for the charge transport in organic materials depend significantly on the temperature. As an example, the localisation energy based on electron-phonon coupling decreases significantly at low temperature, as a consequence different transport channels (band-like or hopping) are possible. In this work we investigate whether such phenomena are accompanied by changes of the intermolecular interaction and the orientation of the molecules. We observe an increase of the molecular ordering of zinc(II)phthalocyanine at low temperatures (liquid He) in particular on polycrystalline Au using polarisation dependent near edge X-ray absorption spectroscopy (NEXAFS). This can be understood by an increase of the intermolecular interaction and by a decrease of the electron-phonon coupling. Resonant photoemission data for C1s show a weaker participator resonance intensity at low temperature, which is discussed in terms of different de-excitation channels.