1. Werkstoffe der Elektrotechnik & CENIDE, Universität Duisburg-Essen, Bismarckstraße 81, 47057 Duisburg, Germany
2. Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, Zürich CH-8093, Switzerland
3. Laboratory for Thin Films and Photovoltaics, Empa − Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf CH-8600, Switzerland