1. State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
2. School of Physics and Electronic Information, Yantai University, Yantai 264005, People's Republic of China
3. New Energy (Photovoltaic) Industry Research Center, Qinghai University, Xining 810006, People's Republic of China