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 and Communication Devices School of Electrical and Electronic Engineering, Tianjin University of Technology, Tianjin 300384, China
3. Tianjin Institute of Power Source, Tianjin 300384, P. R. China