1. Beijing
National Laboratory for Molecular Sciences, Department of Polymer
Science and Engineering and the Key Laboratory of Polymer Chemistry
and Physics of the Ministry of Education, College of Chemistry and
Molecular Engineering, Peking University, Beijing 100871, China
2. Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
3. Department
of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States