Dresden 2011 – scientific programme
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O: Fachverband Oberflächenphysik
O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)
O 36.12: Poster
Tuesday, March 15, 2011, 18:30–22:00, P4
Electronic structure of novel air-stable n-type organic semiconductors: A comparison of different bay-substituted perylene-bisimide dyes — •Markus Scholz1, Rüdiger Schmidt2, Sebastian Fiedler1, Achim Schöll1, Frank Würthner2, and Friedrich Reinert1,3 — 1Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg — 2Universitüt Würzburg, Institut für Organische Chemie, 97074 — 3Gemeinschaftslabor für Nanoanalytik, Karlsruher Institut für Technologie, 76021 Karlsruhe
The development of air stable n-conducting organic semiconductors are one of the current bottle necks in organic electronic. We present a comparative analysis of the electronic structure of various bay-substituted perylene bisimide (PBI) dyes, which have already demonstrated very high mobilities in thin film devices. The occupied and unoccupied valence levels were investigated by UPS and IPES, which allows determining the transport gap. Interestingly, the transport gap does not differ substantially between the different compounds. If the contact properties to a Ag(111) metal substrate are investigated, work function measurements reveal strong interface dipoles. In case of PBIs with fluoro alkyl chains the interface dipole is about 0.7 eV, which can be related to the C4F7-chains oriented out of the film surface. For Films of PBIs with isopropylphenyl-groups the magnitude and the direction of the interface dipole depend strongly on the film preparation and provide a possible route for a tailoring of the interfacial electronic structure.