Cost–effective Polythiophene Counter Electrodes for Dye Sensitized Solar Cells Merve Celik Tolu, Buket Bezgin Carbas and Savas Sonmezoglu E3S Web Conf., 10 (2016) 00006 Published online: 17 October 2016 DOI: 10.1051/e3sconf/20161000006