1. Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
2. Hebei Key Laboratory of Photophysics Research and Application, College of Physics, Hebei Normal University, Shijiazhuang 050024, People's Republic of China
3. School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
4. Wuhan Britain-China School, Wuhan 430030, People's Republic of China