1. Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 P. R. China
2. University of Chinese Academy of Sciences Beijing 100049 P. R. China
3. Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering Changzhou 213164 P. R. China
4. School of Biological and Chemical Engineering NingboTech University Ningbo 315199 P. R. China