1. School of Materials Science and Engineering, Shanghai University, 333 Nanchen Road, Shanghai 200444, China
2. School of Materials Engineering, Shanghai Information Technology College, 1008 Zhennan Road, Shanghai 200331, China
3. SHU-Solar E R&D Lab, Department of Physics, College of Sciences, Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University, 99 Shangda Road, Shanghai 200444, China
4. State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China