Berlin 2008 – wissenschaftliches Programm

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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 5: Poster Session SYSA

SYSA 5.18: Poster

Dienstag, 26. Februar 2008, 14:30–20:00, Poster A

Strong screening in photoemission at interfaces between organic semiconductors and gold: polarization effects versus charge transfer — •Daniel Kolacyak¹, Heiko Peisert¹, André Petershans², and Thomas Chassé¹ — ¹Universität Tübingen, Institut für Physikalische Chemie — ²Forschungszentrum Karlsruhe, Institut für Technische Chemie

We studied electronic polarization effects at organic/metal interfaces using combined photoemission spectroscopy (PES) and x-ray excited Auger electron spectroscopy (XAES) as a function of the organic layer thickness. As a model system, sandwich structures of metall-phthalocyanines (e.g consisting of PcMg and PcZn) were deposited on gold. It was found, that the screening of the photohole is remarkably increased for molecules directly at the interface whereas further layers are affected weakly. This may be caused by a fast charge transfer across the interface as a result of the photoionization due to the overlap organic/metal wave functions. Furthermore, differences in the screening were found for buried molecules and molecules on the surface of the organic film ascribed to different polarization energies. The influence of the morphology and orientation was studied by comparing different substrates: polycrystalline gold foil and single crystalline Au(100).