1. Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
2. College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry, Beijing Normal University, Beijing 100875, People’s Republic of China
3. Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, United Kingdom
4. Institute for Solid State Physics, Abbe Center of Photonics, Friedrich-Schiller-University Jena, Max-Wien-Platz 1, 07743 Jena, Germany
5. School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287, United States
6. Department of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano Italy
7. IFN-CNR, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
8. Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
9. Centre for Optical Fibre Technology, The Photonics Institute, Nanyang Technological University, Singapore 639798, Singapore