We measure the optical and electrical properties of nanocomposites thin films made of poly-3-hexilthiophene and multi-walled carbon nanotubes (MWNT) filled with iron/iron-oxide, as well as the performance of photovoltaic devices built with such films. We find that the devices efficiency has a maximum for a certain MWNT concentration and that the electrical behavior is mainly dependent on the charge transport properties of the MWNT. To improve some engineering aspects, a bilayer geometry is proposed, allowing rectifying J x V characteristics curves. (c) 2006 Elsevier B.V. All rights reserved.