1. Beijing
National Laboratory for Molecular Sciences, Key Laboratory of Organic
Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
2. University of Chinese Academy of Sciences, Beijing 10049, P. R. China
3. DSM DMSC R&D Solutions, P.O. Box 18, 6160 MD Geleen, The Netherlands
4. Molecular Materials and Nanosystems & Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
5. National Center for Nanoscience and Technology, Beijing 100190, P. R. China
6. Biomolecular
and Organic Electronics, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden