1. College of Chemical and Pharmaceutical Engineering Hebei University of Science and Technology #26 Yuxiang Street, Yuhua District Shijiazhuang 050018 P. R. China
2. Institute of Photoelectronic Thin Film Devices and Technology Solar Energy Research Center Nankai University Key Laboratory of Photoelectronic Thin Film Devices and Technology of Tianjin Engineering Research Center of Thin Film Optoelectronics Technology (MoE) #38 Tongyan Road, Jinnan District Tianjin 300350 China