Widespread implementation of photovoltaic electricity to meet changing energy demands requires a step-change in the cost of photovoltaic power. This proposal assembles a consortium of chemists, physicists and materials scientists from Imperial College London and the universities of Manchester, Sheffield and Durham to produce new prototype polymer solar cells that have high power conversion efficiencies and could be mass produced cost effectively. We propose new polymer solar cell designs that integrate flexibility with inexpensive materials and solution based processing. In one approach, block copolymers are used to direct formation of nanostructured thin films to provide high efficiency polymer solar cells. In a second approach, block copolymers will be used to direct crystallisation within nanostructured films. Independent optimisation of the optical and electronic properties, together with theoretical modelling input, will provide design rules for maximising power conversion efficiency. The project will establish strategies for scaling up the device designs which have the highest efficiencies. Our objective is to construct affordable and scalable polymer solar cells that have an energy conversion efficiency of at least 7%.