1. Centre for Disruptive Photonic Technologies, Nanyang Technological University, 637371, Singapore
2. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore
3. Interdisciplinary Graduate School (IGS), Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
4. Department of Physics, University of Warwick, Gibbet Hill Rd., Coventry CV4 7AL, UK
5. Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
6. Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Jiangsu National Synergistic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (Nanjing Tech), Nanjing 211816, China
7. School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore