1. State Key Laboratory of New Ceramics and Fine Processing; School of Materials Science and Engineering; Tsinghua University; Beijing 100084 China
2. Centre for Sustainable Energy Systems; Research School of Engineering; Australian National University; Canberra ACT 2601 Australia
3. School of Materials Science and Engineering; University of Science and Technology Beijing; Beijing 100083 China
4. State Key Laboratory of Marine Resource Utilization in South China Sea; Materials and Chemical Engineering Institute; Hainan University; Haikou 570228 China
5. State Key Laboratory of Electronic Thin Film and Integrated Devices; University of Electronic Science and Technology of China; Chengdu 610054 P. R. China
6. Australian Centre for Advanced Photovoltaics; School of Photovoltaic and Renewable Energy Engineering; University of New South Wales; Sydney NSW 2052 Australia