1. Key Laboratory of Optoelectronic Technology and System of Ministry of Education, College of Optoelectronic Engineering, Chongqing University, Chongqing, 400044, P. R. China
2. Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117574, Singapore
3. Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
4. Berkeley Educational Alliance for Research in Singapore (BEARS), Ltd., 1 Create Way, Singapore, 138602, Singapore
5. Materials Sciences Division and Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States