1. Department of Physics and Organic and Carbon Electronics Laboratories (ORaCEL) North Carolina State University Raleigh NC 27695 USA
2. Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction Hong Kong University of Science and Technology (HKUST) Clear Water Bay Kowloon Hong Kong China
3. Department of Chemistry University of North Carolina at Chapel Hill Chapel Hill NC 27599 USA