1. The Key Laboratory of Solar Thermal Energy and Photovoltaic System, Institute of Electrical engineering, Chinese Academy of Sciences, Beijing 100190, China
2. School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083, China
3. Research and Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China