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US researchers at the University of Washington have taken a new approach to the design of solar cells that more than doubles efficiency.

In dye-sensitized solar cells, a thin layer of tiny particles – nanoparticles – on the surface of the device are used to capture light (in the form of photons), which is then converted into a current of electricity. If the layer of dye particles is kept thin, a significant proportion of the light hitting the device passes straight through and is wasted. However, increasing the thickness of the layer reduces the efficiency of producing electricity from the device. To get around this catch-22, the researchers created popcorn-like balls with the nanoparticles to increase the chance of capture light without adding to the thickness of the layer. The popcorn balls of zinc oxide bounce the light around inside the layer, rather like a ball in a pinball machine, increasing the likelihood that it will be captured by a dye particle. “The result is that we doubled the light to electrical energy conversion efficiency,” says Guozhong Cao. “We think this can lead to a significant breakthrough in dye-sensitized solar cells.” The researchers hope that the improvement in efficiency, if it can be reproduced with titanium oxide based solar cells, could make this type of solar cell a viable possibility.

For further information: http://depts.washington.edu/solgel/