1. Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
2. Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States
3. Center for Advanced Low-Dimension Materials, Donghua University, Shanghai 200051, China
4. Materials Department University of California, Santa Barbara, California 93106, United States
5. Center for Polymers and Organic Solids, University of California, Santa Barbara, California 93106, United States
6. Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States