1. Department of Chemistry, University of Washington, Seattle, Washington 98195-2120, United States
2. Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195-2120, United States
3. School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
4. Department of Physics and Organic and Carbon Electronics Lab (ORaCEL), North Carolina State University, Raleigh, North Carolina 27695, United States
5. Department of Biology and Chemistry and Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong