1. Sensors and Electron Devices Directorate, CCDC Army Research Laboratory, Adelphi, Maryland 20783, United States
2. Department of Chemistry, State University of New York at Binghamton, Binghamton, New York 13902, United States
3. Department of Physics, Central Michigan University, Mt. Pleasant, Michigan 48859, United States
4. Laboratory of Advanced Materials, Department of Materials Science and Collaborative Innovation Center, Fudan University, Shanghai 200438, China