1. The Organic Photonics and Electronics Group Department of Physics Umeå University Umeå SE‐90187 Sweden
2. LunaLEC AB Linnaeus väg 24 Umeå SE‐90187 Sweden
3. Center for Organic Photonics and Electronics Research (OPERA) Kyushu University 744 Motooka, Nishi‐ku Fukuoka 819‐0395 Japan
4. College of Physical Science and Technology & Microelectronics Industry Research Institute Yangzhou University Yangzhou 225002 P. R. China