1. Key Laboratory of Photo-Electronic Thin film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Photo-electronic Technology, Ministry of Education, Institute of Photo-Electronic Thin Film Devices and Technology of Nankai University, Tianjin 300350, P.R. China
2. Tianjin Key Laboratory of Film Electronic & Communicate Devices School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384, P.R. China
3. Tianjin Institute of Power Source, Tianjin 300384, P.R. China