Greg P. Smestad, Ph.D. developed a prototype nanocrystalline dye sensitized solar cell kit in 1998, using dyes from plants and this kit is available from The Institute for Chemical Education (ICE) for $50. The
Nanocrystalline Dye-Sensitized Solar Cell Kit is designed to to teach students how to fabricate a solar cell.
Sol Ideas sold the kit previously, but still has some good directions, reference information, and links on their site. The dye is prepared from blackberries, raspberries, pomegranate seeds, Bing cherries, or green citrus leaves, fresh or frozen. There are a lot of items that are needed and are not in the kit so check out the list at the link on the ICE page.