Combining conjugated poylmers and TiO2 in hybrid bulk-heterojunctions is a promising method for producing novel solar cells. Here TiO2 is introduced into a poly(p-phenylene vinylene) layer. Nanometer-scale phase separation allows efficient photoinduced charge transfer between the two components. The films can be used as the active layer in a photovoltaic cell and provide external quantum efficiencies of up to 11% (see Figure).