1. Shenzhen Key Laboratory of Polymer Science and TechnologyCollege of Materials Science and EngineeringShenzhen University Shenzhen 518060 P. R. China
2. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong ProvinceCollege of Optoelectronic EngineeringShenzhen University Shenzhen 518060 P. R. China
3. Department of Chemistry and Hubei Key Lab on Organic and Polymeric Optoelectronic MaterialsWuhan University Wuhan 430072 P. R. China