1. Institute of Polymer Optoelectronic Materials & Devices, State Key Laboratory of Luminescent Materials & Devices, South China University of Technology, Guangzhou 510640, P. R. China
2. Biomolecular and Organic Electronics, Department of Physics, Chemistry
and Biology, Linköping University, Linköping 58183, Sweden
3. The Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, United States