1. Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics and Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan
2. Department of Chemistry, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Wuhan University, Wuhan 430072, P. R. China
3. Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, P. R. China