Excitonic Solar Cells (ESCs) are a class of non-conventional solar cells, based on organic and nanostructured materials, in which the charge carriers are generated and simultaneously separated across a heterointerface. They include dye-sensitized nanocrystalline cells, organic cells and hybrid organic-inorganic cells, and in all cases cell fabrication can be achieved using low cost, large area deposition methods on both rigid and flexible substrates. Consequently, ESCs offer genuine medium to long term prospects for reducing the cost of PV below the commercially important threshold of $1 per watt peak. To date work on all types of ESC has been largely restricted to basic studies in academic and national research laboratories, with particular emphasis on improving device understanding and cell efficiency, which are 11% for state of the art dye cells, and much lower for the less well developed organic (4-5%) and hybrid cells (2-3%). However, progress in all types of ESC has undoubtedly been impressive in recent years, with research activity growing rapidly throughout the world. Major improvements in performance have been demonstrated in all cell types with the SUPERGEN Consortium at the forefront of much of this progress. There have also been initial steps to commercialise some ESCs, with the first manufacturing plant to produce dye sensitised cells opening in the UK in 2007. However, much fundamental research still needs to be carried out, in particular on the less well developed organic and hybrid cells, but also on the more mature dye cells where many important challenges must be addressed to enable future successful commercialisation. The UK is in an excellent position to lead this activity in an emerging area of PV technology and renewed SUPERGEN funding will enable the Consortium to remain at the forefront of innovative research, while exploiting its strong connections to a number of relevant commercial organisations.Our proposed Main Core programme builds on the successes of our first SUPERGEN project which benefited strongly from the integration of expertise and knowledge in the two main areas of excitonic solar cells, namely dye sensitised cells and organic cells. We will continue to promote cross-fertilisation of ideas for optimising existing cell types and for innovating new types of cells, with the overall aim of improving the performance of different types of ESC. Training will remain a key priority for the Consortium and the exchange of PDRAs and PhD students between the partner universities will ensure the highest quality multi-disciplinary research environment. The UK has a very strong international position in research into ESCs and the renewal of the SUPERGEN programme will help ensure it remains both competitive and innovative in future years.