1. Department of Physics; The Chinese University of Hong Kong; Shatin Hong Kong
2. College of Physics and Energy; Fujian Normal University; Fuzhou 350007 China
3. CAS Key Laboratory of Materials for Energy Conversion; Department of Materials Science and Engineering; University of Science and Technology of China; Hefei 230026 China
4. Department of Physics; Southern University of Science and Technology; Shenzhen 518055 China
5. Center for Information Photonics and Energy Materials; Shenzhen Institutes of Advanced Technology; Chinese Academy of Sciences; Shenzhen 518055 China