1. The Organic Photonics and Electronics Group, Department of Physics, Umeå University, SE-901 87 Umeå, Sweden
2. Department of Materials Science and Engineering, Rutgers University, 607 Taylor Road, Piscataway, New Jersey 08854, United States
3. The Transport and Separations Group, Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping, Sweden