Could spinach be the answer to truly green solar panels?
25th September 2012

A team of researchers at Vanderbilt University in Tennessee have found a way to combine silicon, a key component of solar cells, with the protein in spinach that converts light into energy to create a cell made from readily available materials.

Scientists have known for 40 years ago that this Photosystem 1 (PS1) protein can carry out photosynthesis even when extracted. As it converts almost 100 per cent of sunlight into electricity, more than double the efficiencies of today's best photovoltaic panels, researchers all over the world have been trying to integrate PS1 into highly productive solar cells.

But now, in a paper published in the journal Advanced Materials last week, the Vanderbilt team outlined how they combined PS1 with silicon to produce 2.5 times more electrical current than has been reported by previous "biohybrid" solar cells and a small increase in voltage.

David Cliffel, associate professor of chemistry at the university,said:"People are trying to get around limitations in semi-conductors with fancy, multi-element devices," he said. "But molecular biology is a better known game than these complicated multi-element inorganics. Our components are also non-toxic [and] they literally grow on trees."

The researchers have applied for a patent for the technology and now plan to build a function PS1-silicon cell using the new design.

There are still challenges to be overcome: the amount of power produced per square inch is still far below current photovoltaic technology, and early test cells deteriorated within weeks.

But Cliffel said the proteins "live a lot longer than people think" and was confident if the team could continue to increase voltage and current levels, PS1-silicon could reach the range of mature solar conversion technologies in three years. However, commercialisation still remains a long way off.

"In the short term, current photovoltaics are already well established," Cliffel added. "But if we can realise the improved aspects biomimetic efforts bring, [they] could win out in the longer term."