1. Department of Chemistry and Centre for Processable Electronics Imperial College London White City Campus London W12 0BZ UK
2. Department of Physics and Centre for Processable Electronics Imperial College London South Kensington London SW7 2AZ UK
3. Institute of Molecular Plus Tianjin Key Laboratory of Molecular Optoelectronic Science Tianjin University Tianjin 300072 P. R. China
4. Department of Materials Science and Engineering Monash University Victoria 3800 Australia
5. KAUST Solar Center (KSC) King Abdullah University of Science and Technology (KAUST) Thuwal 23955–6900 Saudi Arabia