1. Institute of Photoelectronic Thin Film Devices and Technology of Nankai University, Tianjin Key Laboratory of Efficient Utilization of Solar Energy, Engineering Research Center of Thin Film Photoelectronic Technology, Ministry of Education, State Key Laboratory of Photovoltaic Materials and Cells, Tianjin 300350, P. R. China
2. School of Materials Science and Engineering, Key Laboratory for Ecological-Environment Materials of Jiangsu Province, Yancheng Institute of Technology, Yancheng, 224051, P. R. China
3. 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