Thienopyrazine-based low-bandgap polymers for flexible polymer solar cells S. Sensfuss, L. Blankenburg, H. Schache, S. Shokhovets, T. Erb, A. Konkin, A. Herasimovich, S. Scheinert, M. Shahid, S. Sell and E. Klemm Eur. Phys. J. Appl. Phys., 51 3 (2010) 33204 Published online: 02 September 2010 DOI: 10.1051/epjap/2010103