ISRAEL is a country with plenty of sunshine, lots of sand and quite a few clever physicists and chemists. Put these together—having first extracted the oxygen from the sand, to leave pure silicon—and you have the ingredients for an innovative solar-power industry. Shining sunlight onto silicon is the most direct way of turning it into electricity (the light knocks electrons free from the silicon atoms), but it is also the most expensive. The scientists are what you need to make the process cheaper. And that is what two small companies based in Jerusalem are trying, in different ways, to do...
 
Jonathan Goldstein of 3GSolar hopes to get rid of silicon altogether. 3G’s “dye-sensitised” solar cells use titanium dioxide (more familiar as a pigment used in white paints) and complicated dye molecules that contain a metal called ruthenium. When one of the dye molecules is hit by light of sufficient energy, an electron is knocked out of it and absorbed by the titanium dioxide, before being passed out of the cell to do useful work.
 
This is a well-known process (it was invented 20 years ago by Michael Grätzel, a physicist at the Federal Polytechnic School in Lausanne, Switzerland) and several firms are trying to commercialise it. Dr Goldstein, however, thinks 3G has an edge over its rivals because of the way it draws off the power—though he is reluctant to go into details. One thing that is clear, though, is that dye-sensitised cells will be cheap to make. Both silicon cells and a third technology, so-called thin-film cells (which use novel materials such as cadmium telluride deposited onto sheets of glass or steel), have to be made in a vacuum. That is expensive. Dye-sensitised cells can be made by a process similar to screen printing, which is cheap.
 
Dye-sensitised cells are not as efficient as silicon ones, but their cheapness may outweigh that in many applications. As Barry Breen, 3G’s boss, points out, more than a billion and a half people have no access to grid electricity. With people like Dr Reisfeld and Dr Goldstein around, soon that may not matter.