1. Freiburg Materials Research Center, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
2. Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany
3. Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, 79110 Freiburg, Germany