1. Department of Chemistry & Centre for Processable Electronics Imperial College London London W12 0BZ UK
2. KAUST Solar Center (KSC) King Abdullah University of Science and Technology (KAUST) Thuwal 23955‐6900 Saudi Arabia
3. Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology Hong Kong SAR 999077 Hong Kong
4. State Key Laboratory of Advanced Displays and Optoelectronics Technologies The Hong Kong University of Science and Technology Hong Kong SAR 999077 Hong Kong
5. Department of Physics The Chinese University of Hong Kong Shatin Hong Kong SAR 999077 Hong Kong