1. Department
of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore
2. Hefei National Laboratory for Physical Sciences at the Microscale, CAS Centre for Excellence and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
3. Department
of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore
4. SZU-NUS
Collaborative Innovation Center for Optoelectronic Science and Technology, Shenzhen University, Shenzhen 518060, China
5. Institute
for Advanced Study and Department of Physics, Nanchang University, 999 Xue Fu Da Dao, Nanchang 330031, China
6. Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (Nanjing Tech), 30 South Puzhu Road, Nanjing 211816, China
7. Institute
of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications (NJUPT), 9 Wenyuan Road, Yadong Xincheng
Distribution, Nanjing 210023, China
8. National University of Singapore (Suzhou) Research Institute, 377 Lin Quan Street, Suzhou Industrial
Park, Suzhou 215123, China
9. Center
for Advanced 2D Materials and Graphene Research Center, National University of Singapore, 3 Science Drive 3, 117546 Singapore