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