With continuous and nanometre-scale interpenetrating phases of electron donor and acceptor components, a novel diblock copolymer, in which one block is poly(p-phenylene vinylene) (PPV) and the other is a C-60-functionalized polystyrene, is designed to be an efficient photovoltaic material. The synthesis involves the polymerization of a styrene derivative from a PPV-based macroinitiator via living free radical polymerization, and its subsequent functionalization with C-60 via atom transfer radical addition. In selective solvents for the polystyrene block, aggregation is detected by means of optical spectroscopy and small-angle neutron scattering. Solid films exhibit honeycomb-structuring at the micrometre level when cast from CS2. As active layer in a device, the donor-acceptor diblock copolymer shows enhanced photovoltaic response relative to a blend of its constituent polymers.