1. Department of Physics, Imperial College London, London, SW7 2AZ, United Kingdom
2. Department of Chemistry, Imperial College London, London, W12 0BZ, United Kingdom
3. Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, OX1 3TA, United Kingdom
4. Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
5. Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
6. Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, United States
7. Physical Sciences and Engineering Division, KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
8. Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States