1. MOE Key Laboratory of Macromolecular Synthesis and Functionalization State Key Laboratory of Silicon Materials Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 P. R. China
2. Department of Chemistry Zhejiang University Hangzhou 310027 P. R. China
3. Institute of Polymer Optoelectronic Materials and Devices State Key Laboratory of Luminescent Materials and Devices South China University of Technology Guangzhou 510640 P. R. China
4. Department of Physics The Chinese University of Hong Kong New Territories Hong Kong 999077 P. R. China