1. Institute for Photovoltaics (ipv), University of Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart, Germany
2. Helmholtz Young Investigator Group, IEK5-Photovoltaik, Forschungszentrum Jülich, 52425 Jülich, Germany
3. Department of Physics and Materials Science, University of Luxembourg, L-1511 Esch-sur-Alzette, Luxembourg
4. Instituto de Ciencia de Materiales (ICMUV), Universidad de Valencia, Paterna, Valencia 46980, Spain
5. Chair of Applied Physics and Semiconductor Spectroscopy, Brandenburg University of Technology Cottbus-Senftenberg, Konrad-Zuse-Straße 1, 03046 Cottbus, Germany