1. Center for Nano Science and Technology, Istituto Italiano di Tecnologia (IIT), Via Pascoli 10, 20133, Milano, Italy
2. Physics Department, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy
3. Institute for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche (CNR), Piazza L. da Vinci 32, 20133 Milano, Italy
4. Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA
5. School of Chemical and Biomedical Engineering, Nanyang Technological University Singapore 639798, Singapore
6. Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University Singapore 639798, Singapore