1. Key Laboratory of
Optoelectronic Technology and Intelligent Control of Ministry Education, Lanzhou Jiaotong University, Lanzhou 730070, P. R. China
2. 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
3. Center for Polymers and Organic Solids, University of California, Santa Barbara, California 93106-5090 United States