Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 44: Organic semiconductors I

HL 44.1: Talk

Thursday, March 26, 2009, 10:45–11:00, POT 51

Charge transfer and polarization screening at organic-metal interfaces — •Heiko Peisert, Daniel Kolacyak, and Thomas Chassé — University of Tübingen, Institute of Physical and Theoretical Chemistry, Auf der Morgenstelle 8, 72076 Tübingen, Germany

Core hole screening effects at organic/metal interfaces were studied using core level X-ray photoemission spectroscopy (XPS), x-ray excited Auger electron spectroscopy (XAES) and valence band ultraviolet photoemission spectroscopy (UPS). The comparison of energetic shifts in XPS and XAES enables the estimation of electronic relaxation energy (screening ability). Magnesium phthalocyanine (MgPc), zinc phthalocyanine (ZnPc) and perfluorinated zinc phthalocyanine (ZnPcF16) evaporated on single crystalline Au(100) were used as model molecules. Two different features in the metal Auger spectra can be clearly separated for (sub-)monolayer coverages while only minor changes of the shape of corresponding photoemission features are observed. In contrast, Auger spectra of fluorine in ZnPcF16 do not show different components for ultrathin films. Applying a dielectric continuum model, the major screening mechanism cannot be described sufficiently by polarization screening due to mirror charges, significant contributions by charge transfer screening have to be considered. The work was supported by the German Research Council Ch 132/20-1.