1. Physics Department, National University of Singapore, Singapore 117551, Singapore
2. Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
3. Chemistry Department, National University of Singapore, Singapore 117543, Singapore
4. Science, Mathematics, and Technology, Singapore University of Technology and Design (SUTD), Singapore 487372, Singapore
5. Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Singapore
6. Research Centre for Functional Materials, National Institute for Materials Science, Tsukuba 305-0047, Japan
7. International Centre for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0047, Japan
8. Centre for Advanced 2D Materials, National University of Singapore, Singapore 117546, Singapore
9. Institute for Functional Intelligent Materials, National University of Singapore, Singapore 117544, Singapore