'Nanowires can boost solar cells' efficiency'

Last Updated: Mon, Jan 21, 2013 06:20 hrs

Stockholm, Jan 21 (IANS) Nanowires could pave the way for more efficient and cheaper solar cells, new research from Sweden says.

"Our findings are the first to show that it really is possible to use nanowires to manufacture solar cells," says Magnus Borgstrom, researcher in semiconductor physics at Sweden's Lund University, who led the study.

Research on solar cell nanowires is on the rise globally. Until now, for researchers the dream figure was 10 percent efficiency - but now Borgstrom and colleagues are able to report an efficiency of 13.8 percent, the journal Science reports.

The nanowires are made of the semiconductor material indium phosphide and work like antennae that absorb sunlight and generate power.

The nanowires are assembled on surfaces of one square mm that each house four million nanowires. A nanowire solar cell can produce an effect several times greater than today's silicon cells.

Nanowire solar cells have not yet made it beyond the labs, but the plan is that the technology could be used in large solar power plants in sunny regions such as the south-western US, southern Spain and Africa, according to a Lund statement.

The researchers have now managed to identify the ideal diameter of the nanowires and how to synthesise them.

"The right size is essential for the nanowires to absorb as many photons as possible. If they are just a few tenths of a nanometre too small their function is significantly impaired," says Borgstrom.

The silicon solar cells that are used to supply electricity for domestic use are relatively cheap, but inefficient because they are only able to utilise a limited part of the effect of the sunlight. The reason is that one single material can only absorb part of the spectrum of the light.

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