1. 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
2. Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials South China University of Technology Guangzhou 510640 P. R. China
3. State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116024 P. R. China