1. Department of Mechanical Engineering, EPFL, 1015 Lausanne, Switzerland
2. Department of Electronics/Metrology, EMPA Material Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland
3. Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland; Solar Technology Laboratory, Paul Scherrer Institute, 5232 Villigen, Switzerland