1. Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
2. Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
3. Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu City 300, Taiwan
4. Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
5. Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States