1. Laboratory for Photovoltaics (LPV) Department of Physics and Materials Science University of Luxembourg 41 rue du Brill Belvaux L‐4422 Luxembourg
2. Institute for Solar Energy Research Hamelin (ISFH) Am Ohrberg 1 D‐31860 Emmerthal Germany
3. Luxembourg Institute of Science and Technology (LIST) Materials Research and Technology Department 41 rue du Brill Belvaux L‐4422 Luxembourg
4. Institute of Solid‐State Physics Leibniz University Hannover Appelstr 2 30167 Hannover Germany