* Corresponding authors

^a Department of Chemistry and Centre for Plastic Electronics, Imperial College London, UK
E-mail: m.heeney@imperial.ac.uk

^b Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University, Tianjin, P. R. China

^c Department of Materials and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK

^d Department of Physics and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK

^e Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology, Saudi Arabia