Spinach Solar Cells

Written By Brianna Panzica

Posted September 4, 2012

Solar companies are always trying to find a more efficient way to convert solar power into electrical energy. And what better material to use than plant protein, which is always converting the sun into energy?

Researchers at Vanderbilt University have shown just how powerful spinach can be by coating silicon wafers in an extracted spinach protein, photosystem 1 (PS1). With the plant protein coat, the wafers produced electrical current levels two and a half times above those of other biohybrid solar cells.

The efficiency of PS1 was discovered over 40 years ago, when researchers realized it would still go on converting sunlight to energy even after it was extracted from the plant. More than that, it had almost 100% efficiency in its conversion.

But it wasn’t easy to determine how to apply this efficiency to solar cells to make what they called a biohybrid cell. The biohybrid cells developed since then produced less electricity per square inch than regular photovoltaic cells. And the performance deteriorated after only a short time.

The Vanderbilt team, however, was able to make the cells last nine months and produce a milliamp of current per square centimeter at 0.3 volts – two and a half times better than any biohybrid cell to date.

From Phys.org:

“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 Davide Cliffel, associate professor of chemistry, who collaborated on the project with Kane Jennings, professor of chemical and biomolecular engineering. “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.”

One of the secrets to the Vanderbilt researchers’ success was the process of doping the silicon. They found that if they doped the silicon with a positive atomic charge, the PS1 molecule worked well.

Previous models faced the problem of individual protein ordering. In nature, they are aligned, but once removed from the spinach leaf and put on the silicon, they are randomized. The positive doping allowed electrons to flow in the same direction, not necessarily ordering the PS1 again but still solving the problem.


A two-foot panel like this could power a number of small electronics, the researchers estimated.

The research was published in Tuesday’s issue of Advanced Materials, and Vanderbilt University is looking to patent the process.

That’s all for now,

Brianna Panzica

follow basic@brianna_panzica on Twitter

Energy & Capital’s modern energy guru, Brianna digs deep into the industry with accurate and insightful updates into the biggest energy companies and events. She stays up to date with the latest market moves and industry finds, bringing readers a unique view of current energy trends.

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