“In all solar cells now in use, each incoming photon contributes at most one energized electron to the electric current it generates.
Victor Klimov, a physicist at Los Alamos National Laboratory in New Mexico, has found that by shrinking the elements of a solar cell down to a few nanometers, or millionths of a millimeter, each captured photon can be made to generate not one, but two or even more charge carriers
The new approach is unique in that it gets to the very root of the process and also complements other methods.
Most solar panels have an efficiency of around 10-15% and the current world record for ground based panels is 24.7% (about the efficiency of a petrol engine).
This new technology could one day yield solar cells with an efficiency approaching 50 per cent.”
(Herb Brody, “Two for the price of one”, NewSscientist, Vol 2553, 27 May, 2006, pp44-47)