1. College of Physics and Information Engineering, Institute of Micro-Nano Devices and Solar Cells, Fuzhou University, Fuzhou, Fujian 350108, P. R. China
2. Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian 350108, P. R. China
3. School of Information Engineering, Institute of Space Science and Technology, Nanchang University, Nanchang, Jiangxi 330031, P. R. China
4. Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Changzhou 213164, P. R. China