Berlin 2008 – scientific programme
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DS: Fachverband Dünne Schichten
DS 4: Organic Thin Films
DS 4.3: Talk
Monday, February 25, 2008, 16:45–17:00, H 2013
Electronic properties of thin halogenated perylene bisimide films on Ag(111). — •Markus Scholz1, Stefan Krause1, Rüdiger Schmidt2, Frank Würthner2, Achim Schöll1, Friedrich Reinert1, and Eberhard Umbach1,3 — 1Universität Würzburg, Experimentelle Physik II, 97074 Würzburg — 2Universität Würzburg, Institut für Organische Chemie, 97074 Würzburg — 3Forschungszentrum Karlsruhe, 76021 Karlsruhe
A majority of organic semiconductors exhibit p-channel behavior. For complementary circuits both p-type and n-type semiconductors are necessary. Perylene tetracarboxylic acid bisimides (PBI) are not only considered to be among the best n-type organic semiconductors available, but also their structural properties, e.g. the twist angle of the perylene core as well optical and electronic properties can be tuned by proper substituents at the perylene core.
While previous investigations on bay-substituted perylene bisimides were performed in solution or addressed the electron mobility in thin films, we focused on the electronic structure of thin condensed films of PBI-H4, core chlorinated PBI-Cl4, and core fluorinated PBI-F2 on Ag(111) substrates with x-ray and UV photoelectron spectroscopy (XPS/UPS) and inverse photoemission spectroscopy (IPES). Particular respect was given to the influence of different bay-substituents, which allow to vary the twist angle of the perylene core and thus possibly the intermolecular π-overlap. Additionally, the attenuation behavior of the substrate peaks allows conclusions about the growth mode.