We report a polythiophene/fullerene (C-60) bulk heterojunction solar cell fabricated via electrochemical co-deposition of polythiophene (PTh) and fullerene on an indium tin oxide (ITO) glass electrode modified with a thin layer of poly (3,4-ethylenedioxylthiophene) (PEDOT). Although the amount of C-60 incorporated into the film was relatively low, the photovoltaic performance of the cell based on the polythiophene/fullerene (PTh/C-60) composite film was remarkably improved. (c) 2006 Elsevier B.V. All rights reserved.