1. Department of Chemical and Biomolecular Engineering; National University of Singapore; 4 Engineering Drive 4 Singapore 117585 Singapore
2. Department of Chemistry and Centre for Advanced 2D Materials; National University of Singapore; 3 Science Drive 3 Singapore 117543 Singapore
3. School of Materials Science and Engineering; Nanyang Technological University; 50 Nanyang Avenue Singapore 639798 Singapore
4. Nanoscience & Nanotechnology Initiative (NUSNNI)-Nanocore; National University of Singapore; Singapore 117576 Singapore
5. Beijing National Laboratory for Molecular Sciences; Organic Solids Laboratory; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 China