1. Adolphe Merkle Institute, Chemin des Verdiers 4, CH-1700 Fribourg, Switzerland
2. Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland
3. Institute for Photovoltaics (ipv), Pfaffenwaldring 47, 70569 Stuttgart, Germany
4. Helmholtz Young Investigator Group FRONTRUNNER, IEK5 Photovoltaics, Forschungszentrum Jülich, 52425 Jülich, Germany