1. Beijing National Laboratory for Molecular Sciences; CAS 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 100049 P. R. China
3. Department of Materials Science and Engineering; College of Engineering; Key Laboratory of Polymer Chemistry and Physics of Ministry of Education; Peking University; Beijing 100871 P. R. China
4. State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 P. R. China
5. Key Laboratory of Luminescence and Optical Information; Ministry of Education; Beijing Jiaotong University; Beijing 100044 P. R. China
6. National Center for Nanoscience and Technology; Beijing 100190 P. R. China
7. Heeger Beijing Research and Development Center; School of Chemistry and Environment; Beihang University; Beijing 100191 P. R. China