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US lab births flexy, stingy solar cells

99 per cent less silicon

A team of US research scientists have made a startling breakthrough in solar-cell development, creating flexible wire-based cell substrates that use just one per cent of the silicon needed for brittle and comparatively heavy conventional cells.

Solar cells made from this material would not only be less expensive than current photovoltaics, but due to their low weight and bendable structure the could be used in a wide variety of applications. Solar curtains, anyone?

The new technique is described in a paper nimbly entitled "Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications" published in Nature Materials by a team of researches from the California Institute of Technology in Pasadena.

The trick in this new method is to bundle one-micrometer-thick silicon wires and embed the resulting array vertically in a flexible polymer. Thus bundled, the paper claims, the array could capture and transmit up to 96 per cent of light in peak conditions while requiring only one per cent of the silicon needed by conventional cells.

What's more, the wire arrays would have work over "over a broad range of incidence angles," thus capturing light efficiently with less need to be reoriented.

The researchers achieved their best results when coating the ends of the wires with an anti-reflective material, and predict that solar cells built using this technique would achieve efficiencies of around 17 per cent. Today's commercial-grade solar cells are in the 10 to 15 per cent range.

That 17 per cent figure, if achieved, would be impressive for such a flexible, materials-stingy technology. ®

Bootnote

It's been a good few days for solar technology. Just last week, IBM researched announced a new low-cost photovoltaic compound. Perhaps the folks in Armonk and the Pasadena boffins should hold a conference call.

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