Berlin 2008 – scientific programme

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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 5: Poster Session SYSA

SYSA 5.78: Poster

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

Metal work function tuning with new molecular acceptors — •Benjamin Bröker¹, Ralf-Peter Blum¹, Antje Vollmer², Oliver Hofmann³, Steffen Duhm¹, Hendrik Glowatzki¹, Ralph Rieger⁴, Hans Joachim Räder⁴, Klaus Müllen⁴, Jürgen P. Rabe¹, and Norbert Koch¹ — ¹Institut für Physik, Humboldt-Universtität zu Berlin, D-12389 Berlin, Germany — ²Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung mbH, D-12489 Berlin, Germany — ³Institut für Festkörperphysik, Technische Universität Graz, A-8010 Graz, Austria — ⁴Max Planck Institut für Polymerforschung, D-55128 Mainz, Germany

The interfaces between metal electrodes and electroactive organic materials are important for the performance of organic electronic devices. One way of optimizing the anode/organic interface is the insertion of a (sub-)monolayer of molecular acceptors. Here we present an UPS study of new electron acceptor molecules deposited on Au(111), Cu(111) and Ag(111). This study intends to improve the understanding of how the interactions of specific electron withdrawing groups with metal surfaces are correlated with observed modifications of interfacial electron density distribution, work function change (ΔΦ), and the energy level alignment. We find that ΔΦ, which is the difference between the work function (Φ) of the clean metal surface and Φ after formation of a molecular monolayer, is a monotonic function of initial Φ of the metal. Two different slopes were observed for acceptors with cyano and those with keto or nitro groups. This work is financially supported by the European Community project "IControl" (EC-STREP-033197).