1. Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, P.R. China
2. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P.R. China
3. Australian Nuclear Science and Technology Organization, Lucas Heights, NSW 2234, Australia
4. Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742, United States
5. School of Materials Science and Engineering, Shanghai University, Shanghai 200444, P.R. China
6. Key Laboratory for Renewable Energy Beijing Key Laboratory for New Energy Materials and Devices, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P.R. China