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Protein in Spinach Can Boost Efficiency of Solar Cells

Scientists at Vanderbilt University have discovered a way of using a photosynthetic protein in spinach to improve solar panel efficiency.

The team of biomolecular engineers and chemists has found a method of combining a photosynthetic protein, which converts sunlight into energy, with silicon, a key component in solar panels, to make a more efficient and ‘greener’ solar cell.

It has been known for decades that Photosystem 1 (PS1), the plant protein in question, has the ability to do photosynthesis even after extraction – in fact, PS1 can convert nearly 100 percent of sunlight into electrical energy. That’s more than double the efficiency of today’s best solar cells, prompting  research into ways to harness PS1’s power to create more efficient solar cells.

However, incorporating this technology to solar cells wasn’t easy. Called a biohybrid cell, early prototypes deteriorated quickly, and the cells didn’t produce much as electricity per square inch as today’s regular silicon cells.

Panel of biohybrid solar cells that Vanderbilt undergraduate engineering student entered in the National Sustainable Design Expo. Credit: Vanderbilt University

But the Vanderbilt team struck gold when they were able to make cells last for up to nine months and produce  a milliamp of current per square centimeter at 0.3 volts, which is 2.5 times better than any biohybrid cell to date.

The team created this successful biohybrid cell by extracting PS1 from spinach and immersing it in an aqueous solution, before transferring the mixture onto the surface of a silicon wafer. They place these wafers in a vacuum chamber to get rid of the water and leave a thin protein film.

It is estimated that a two-foot panel of ‘doped’ cells is able to produce at least 100 milliamps at one volt, enough to power small electrical devices.

“This combination produces current levels almost 1,000 times higher than we were able to achieve by depositing the protein on various types of metals. It also produces a modest increase in voltage,” said David Cliffel, associate professor of chemistry, who collaborated on the project with Kane Jennings, professor of chemical and biomolecular engineering. Their paper was published in the Advanced Materials journal earlier this month.

“If we can continue on our current trajectory of increasing voltage and current levels, we could reach the range of mature solar conversion technologies in three years,” he added.


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