1. Department of Chemical and Biological Engineering/Polymer Technology, Chalmers University of Technology, SE-412 96 Göteborg, Sweden, Biomolecular and Organic Electronics, IFM, Center of Organic Electronics, Linköping University, SE-581 83 Linköping, Sweden, and Department of Chemistry, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia