1. Department of Physics, Umeå University, Umeå SE-90187, Sweden
2. LunaLEC AB, Linnaeus väg 24, Umeå SE-90187, Sweden
3. Department of Photo-Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
4. College of Physical Science and Technology, Yangzhou University, Jiangsu 225009, China
5. Laboratory for Organic Electronics, ITN, Linköping University, Norrköping SE-60174, Sweden