1. Department of Chemistry and Centre for Processable Electronics, Imperial College London, London W12 0BZ, U.K.
2. King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Science and Engineering Division (PSE), Thuwal 23955-6900, Kingdom of Saudi Arabia
3. Department of Physics, National Technical University of Athens, Zografou Campus, Athens 15780, Greece
4. School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 401331, China
5. Research Center for Electronics and Telecommunication, National Research and Innovation Agency, Jalan Sangkuriang Komplek LIPI Building 20 Level 4, Bandung 40135, Indonesia
6. Department of Physics and Centre for Processable Electronics, Imperial College London, London W12 0BZ, U.K.