1. Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstr. 2 79110 Freiburg Germany
2. Freiburg Materials Research Center FMF University of Freiburg Stefan-Meier-Str. 21 79104 Freiburg Germany
3. Cluster of Excellence livMatS University of Freiburg Georges-Köhler-Allee 105 79110 Freiburg Germany