1. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry University of Chinese Academy of Sciences Changchun 130022 People's Republic of China
2. Department of Chemistry, Faculty of Science Xi'an Jiao Tong University Xi'an 710049 People's Republic of China
3. Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering Nanyang Technological University 50 Nanyang Avenue Singapore 639798 Singapore
4. Center of Advanced Science and Engineering for Carbon (Case4Carbon), Department of Macromolecular Science and Engineering, Case School of Engineering Case Western Reserve University 10900, Euclid Avenue Cleveland Ohio 44106 USA