In a technological breakthrough, the photosynthetic protein in spinach has been combined with silicon in a new and unique way, resulting in a solar cell that produces considerably more electrical current than any previous “biohybrid” solar cells.
“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.
“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.”
The researchers next plan to build a functional PS1-silicon solar cell using this new design. They estimate that the new design could allow a two-foot panel to put out at least 100 milliamps at one volt. That’s enough to power a number of different types of small electrical devices.
It was discovered more than 40 years ago that one of the proteins involved in photosynthesis (PS1) was able to function even after it was extracted from plants. And even more impressively PS1 converts sunlight into electrical energy with almost 100 percent efficiency, much more than the conversion efficiencies of less than 40 percent achieved by artificial devices. Since these discoveries, PS1 has been targeted as a way to very high-efficiency solar cells.
Another major advantage of biohybrid solar cells is that they can be made from cheap and easily obtained materials, rather than the rare and expensive materials used in conventional cells, such as platinum or indium.
“The Vanderbilt researchers report that their PS1/silicon combination produces nearly a milliamp (850 microamps) of current per square centimeter at 0.3 volts. That is nearly two and a half times more current than the best level reported previously from a biohybrid cell.”
Apparently the reason that this combo is so good is because “the electrical properties of the silicon substrate have been tailored to fit those of the PS1 molecule,” which was done by implanting electrically charged atoms into the silicon in order to alter its electrical properties. This process is termed ‘doping’. The PS1 protein was found to work extremely well with silicon doped with positive charges, and very poorly with negatively doped silicon.
Source: Vanderbilt News
Image Credits: Julie Turner/Vanderbilt; Amrutur Anilkumar/Vanderbilt University