1. Department of Chemistry, Aalto University, P.O.B. 16100, FI-00076 Aalto, Finland
2. Molecular Materials, Department of Applied Physics, Helsinki University of Technology/Aalto University, Puumiehenkuja 2, FI-02150 Espoo, Finland
3. KSV Instruments, Höyläämötie 7, 00380 Helsinki, Finland
4. Nokia Research Center, Itämerenkatu 11-13, FI-00180 Helsinki, Finland