1. Department of Physics and Materials Science, University of Luxembourg, Luxembourg City L-1511, Luxembourg
2. Institute for Photovoltaics (IPV), University of Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart, Germany
3. Helmholtz Young Investigator Group FRONTRUNNER, IEK5-Photovoltaik, Forschungszentrum Jülich, 52425, Jülich, Germany