Scientists develop tiny solar cells

18 Oct 2007

A team of US scientists have developed solar wire capable of powering tiny devices

Scientists have built a wire out of photosensitive materials that is invisible to the human eye, and could be used to power future nanodevices.

The wire, developed by scientists at Harvard University, is essentially a new kind of solar cell, composed of different types of silicon each with their own electrical properties which not only conduct but generate electricity.

Scientists claim the wire has a number of advantages over existing photovoltaic technologies, not least of which is its flexibility which could see it embedded into clothing and worn comfortably while providing a power source for sensors and other small devices. It is also cheap to manufacture, they say.

Efficiency, however, is still a problem for the team, with figures quoted in the Harvard Science journal suggesting that the wire converts around 3.4% of collected sunlight into electricity, as opposed to the 20% efficiency of commercial solar panels.

"More traditional moderate to large scale power generation will require an improvement in efficiency to make things more economically attractive," says Professor Charles Lieber, a researcher on the Harvard team.

"We believe the efficiency can be improved quite a bit, but it is always hard to predict when next breakthrough will be."

Despite this, the wire has so far been used to power a biological/chemical nanosensor and a logic gate circuit, and the team suggests that commercial rollout may occur within five years.

"The overall technology concept is new and will require time to develop and find niche applications," says Lieber.

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