SOLAR cells could see a boost in their theoretical maximum efficiency from 31 per cent to 66 per cent, thanks to a novel way of harnessing electrons whose energy is normally lost as heat.
The most efficient silicon solar cells turn 25 per cent of the incoming light into electricity, but even with further improvements these cells will reach a theoretical limit at 31 per cent, because incoming light creates large numbers of extremely energetic electrons that lose energy to their surroundings in just a picosecond - too rapidly to be harnessed.
In 2001, Arthur Nozik of the National Renewable Energy Laboratory (NREL) in Golden, Colorado, suggested that quantum dots - nanoscale chunks of semiconducting material - could slow the rate at which "hot" electrons lose energy by 1000 times. That's because the energy ...
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