1 Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, UK. yen-hung.lin@physics.ox.ac.uk.
2 Department of Physics and Centre for Plastic Electronics, Imperial College London, London, SW7 2AZ, UK.
3 Department of Materials Science and Engineering, School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, 21210, Thailand.
4 Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, UK.
5 National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York, 11973, USA.
6 School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR, 97331, USA.
7 Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
8 King Abdullah University of Science and Technology (KAUST), Core Labs, Thuwal, 23955-6900, Saudi Arabia.
9 Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London, SW7 2AZ, UK.
10 Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University, Tianjin, 300072, China.
11 Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia. thomas.anthopoulos@kaust.edu.sa.
12 Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, UK. henry.snaith@physics.ox.ac.uk.