1. Institute of New Energy Technology College of Information Science and Technology Jinan University Guangzhou 510632 China
2. Australian Centre for Advanced Photovoltaics School of Photovoltaic and Renewable Energy Engineering University of New South Wales Sydney NSW 2052 Australia
3. Shenzhen Key Laboratory of Advanced Thin Films and Applications Shenzhen University Shenzhen 518060 China
4. Institute of Photoelectronic Thin Film Devices and Technology Nankai University Tianjin 300071 China
5. Key Laboratory of Polar Materials and Devices (MOE) East China Normal University Shanghai 200241 China
6. School of Metallurgy and Environment Central South University Changsha 410083 P. R. China