1. IEK5‐PhotovoltaikForschungszentrum Jülich Jülich 52425 Germany
2. Institute of Inorganic ChemistryUniversity of Cologne Greinstr. 6 Cologne 50939 Germany
3. Faculty of Engineering and CENIDEUniversity of Duisburg‐Essen Carl‐Benz‐Str. 199 Duisburg 47057 Germany