Polymer solar cells were fabricated based on an interpenetrated network of conjugated polymer poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevi-nylene) (MEH-PPV) as electron donor and fullerene derivative (6,6)-phenyl-C-61-butyric acid methyl ester (PCBM) as electron acceptor. The photovoltaic performances were strongly dependent on the surface treatment of anode, conductivity of hole-transporting material, the thickness of MEH-PPV: PCBM composite film, and the cathode configuration. Best photovoltaic performances were obtained for the solar cell constructed with 0, plasma-treated anode glass, high conductivity hole-transporting material PEDOT, photoactive film thickness of 180 nm, and calcium/silver cathode. Open circuit voltage of 0.79 V, short circuit current density of 4.79 mA/cm(2), fill factor of 44.4%, and 2.07% power conversion efficiency were obtained for the solar cell under 80 mW/cm(2) white light from a halogen lamp. The influences of device fabrication conditions and configuration on the photovoltaic performance of MEH-PPV:PCBM composite film-based polymer solar cells were discussed in detail. (c) 2006 Wiley Periodicals, Inc.