1. Shanghai Key Laboratory of Functional Materials Chemistry, Key Laboratory for Advanced Materials and Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
2. Photovoltaic Materials Group, Center for Green Research on Energy and Environmental Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Japan
3. Physical Chemistry, Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Göteborg, Sweden