1. Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP 1 , Winterbergstraße 28, Dresden D-01277, Germany
2. Institute of Solid State Electronics (IFE), Technische Universität Dresden 2 , Mommsenstraße 15, Dresden D-01069, Germany
3. Synthesis and Real Structure, Department of Material Science, Kiel University 3 , Kaiserstraße 2, Kiel D-24143, Germany
4. Kiel Nano, Surface and Interface Science (KiNSIS), Kiel University 4 , Christian-Albrechts-Platz 4, Kiel D-24118, Germany