1. Institut für Experimentelle Physik I, Universität Leipzig, Linnéstrasse 5, 04103 Leipzig, Germany, Institute of Neuroscience and Medicine, Forschungszentrum Juelich GmbH, 52425 Juelich, Germany, Department of Chemistry, CDE, University of Antwerpen, Universiteitsplein 1, B-2610 Wilrijk, Belgium, and MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, New Zealand