1. State
Key Laboratory for Artificial Microstructure and Mesoscopic Physics,
School of Physics, Peking University, Beijing 100871, China
2. School
of Engineering, Brown University, Providence, Rhode Island 02912, United States
3. Chemistry
and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
4. College
of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
5. State
Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center
of Quantum Matter, School of Physics, Peking University, Beijing 100871, P. R. China
6. Collaborative
Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 020006, P. R. China