1. Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
2. Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
3. Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
4. Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu 30010, Taiwan