1. IEK5-Photovoltaics, Forschungszentrum Jülich, 52425 Jülich, Germany
2. Faculty of Engineering and CENIDE, University of Duisburg-Essen, Carl-Benz-Str. 199, 47057 Duisburg, Germany
3. Shandong Provincial Key Laboratory of Processing and Testing Technology of Glass & Functional Ceramics, School of Materials Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), 250353 Jinan, P. R. China
4. State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou, 350002 Fujian, P. R. China