Large area photovoltaic devices based on an interpenetrating network of donor and acceptor molecules have been fabricated showing power conversion efficiencies up to 1.5% under monochromatic illumination at 500 nm. Devices containing blends of solubilized poly (paraphenylene vinylene), (PPV) or poly thiophene derivatives as donors with various fullerene derivatives as accepters are compared. It is shown that among the various combinations of materials both the open-circuit voltage and the short-circuit current are maximal for a blend of PPV and a highly soluble methano fullerene. For a further increase of the efficiency of these devices, a reduction of the thickness of the active layer is suggested. (C) 2000 Elsevier Science B.V. All rights reserved.