From photocopiers to solar cells

JAPAN'S Canon company, world-famous for its cameras, has adapted a technique used in making photocopiers to produce cheaper and more efficient solar cells. The technique involves sandwiching amorphous silicon between two layers of amorphous silicon germanium (New Scientist, Vol 137, No 1865). Silicon and germanium are semiconductors, which means while they are not conductors in their pure form, they become conductors when doped with impurities.

Solar cells are now made using either slices of crystals such as silicon or noncrystalline semiconductors. The former are more efficient but they are expensive; the latter are cheaper, but their efficiency is low. Canon claims its solar cells will be both cheaper and more efficient.