1. Division of Physical Sciences and Engineering, KAUST Solar Center
(KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
2. Department of Physics, Organic and Carbon Electronics Lab (ORaCEL), North Carolina State University, Raleigh, North Carolina 27695, United States
3. State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China