1. Department of Chemistry, Hubei Key Lab on Organic and Polymeric, Optoelectronic Materials, Wuhan University, Wuhan, Hubei 430072, People’s Republic of China
2. Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, School of Materials Science and Engineering, Peking University, Beijing 100871, People’s Republic of China
3. Department of Physics, The Chinese University of Hong Kong, New Territories 999077, Hong Kong Special Administrative Region of the People’s Republic of China