1. Institute of Photoelectronic Thin Film Devices and Technology and Tianjin Key Laboratory of Thin Film Devices and Technology Nankai University Tianjin 300350 P.R. China
2. Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Tianjin Key Laboratory of Applied Catalysis Science & Engineering School of Chemical Engineering & Technology Tianjin University Tianjin 300072 P. R. China
3. School of Physical Science Nankai University Tianjin 300071 P. R. China
4. College of Electronic Information and Optical Engineering Nankai University Tianjin 300350 P. R. China