Spinach Solar Cells Combine Photosynthesis with Manmade Technology
© Julie Turner/Vanderbilt University
Photosynthesis is the original solar power technology. All manmade solar technology is essentially trying to copy that amazing process of turning sunlight into energy and those efforts have paid paid off. Solar technology has come a long way, with some solar cells able to achieve conversion efficiencies of close to 50 percent in lab settings, but researchers at Vanderbuilt University found that combining both the power of photosynthesis in spinach with the photovoltaic power of silicon could create a solar cell that packs an extra punch.
Vanderbuilt University says:
More than 40 years ago, scientists discovered that one of the proteins involved in photosynthesis, called Photosystem 1 (PS1), continued to function when it was extracted from plants like spinach. Then they determined PS1 converts sunlight into electrical energy with nearly 100 percent efficiency, compared to conversion efficiencies of less than 40 percent achieved by manmade devices. This prompted various research groups around the world to begin trying to use PS1 to create more efficient solar cells.
Another potential advantage of these biohybrid cells is that they can be made from cheap and readily available materials, unlike many microelectronic devices that require rare and expensive materials like platinum or indium.
© Amrutur Anilkumar/Vanderbilt University
Once they figured out how to efficiently extract the PS1 from leaves and confirmed that they could produce electrical current when exposed to sunlight, researchers started working on producing a functional solar cell. So far, biohybrid cells have produced varying amounts of power, usually far below what a conventional photovoltaic cell can, but the Vanderbuilt team found that coupling the PS1 with silicon created a high performing biohybrid cell, capable of producing two to three times more power than previously reported for a biohybrid cell and current levels that are 1,000 times higher than PS1 combined with various types of metals.
To make the spinach cell, Vanderbuilt researchers, "extracted PS1 from spinach into an aqueous solution and poured the mixture on the surface of a p-doped silicon wafer. Then they put the wafer in a vacuum chamber in order to evaporate the water away leaving a film of protein."
The team estimates that a two-foot panel of these "doped" cells could put out at least 100 milliamps at one volt, which would be enough to power gadgets and other small electrical devices. They plan to continue improving the voltage and current levels and think that the technology could be on par with conventional solar cells within three years, but with the advantage of using natural materials.