1. Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, United States
2. Department of Chemistry, University of California, Riverside, California 92521, United States
3. Department of Physics and Astronomy, University of California, Riverside, California 92521, United States
4. School of Physical Science and Technology, Southwest University, Chongqing 400715, China
5. Materials Science and Engineering Program, University of California, Riverside, California 92521, United States
6. Department of Mechanical Engineering, University of California, Riverside, California 92521, United States