1. Department of Physics and Centre for Plastic Electronics; Imperial College London; South Kensington London SW7 2AZ UK
2. Department of Materials and Centre for Plastic Electronics; Imperial College London; South Kensington London SW7 2AZ UK
3. Solar and Photovoltaic Engineering Research Centre and Physical Sciences and Engineering Division; King Abdullah University of Science and Technology (KAUST); Thuwal 23955-6900 Saudi Arabia