1. School
of Chemistry, University of Bristol, Bristol BS8 1TS, U.K.
2. Key Laboratory of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, China
3. Aalto University, Department of Applied Physics,
Molecular Materials, FIN-00076 Espoo, Finland
4. H.
H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
5. Bristol
Centre for Functional Nanomaterials, Nanoscience and Quantum Information
Building, University of Bristol, Tyndall Avenue, Bristol BS8 1FD, United Kingdom