Progress in Solar Energy:

Research Produces First Solar Cell with a Biological Component

Research currently underway at Kansas State University has produced the first solar cell with a biological component.

Ayomi Perera is a doctoral student in Chemistry at Kansas State. She has built a solar cell that incorporates the protein MspA with the help of her research advisor Stefan Bossmann. Solar panels are made of multiple solar cells.

“Essentially what we have is a glass surface which is coated by Titanium dioxide nanoparticles and onto this surface we had absorbed a protein dye complex. The protein is a channel forming protein extracted from a bacteria called Microbacterium Smegmatis and the dye is a new type of ruthenium Phenanthroline based compound which we have synthesized in our labs,” Ayomi said.

The advantage of using a protein in the solar cell design is that proteins are biodegradable.

“It’s sushi yeah, with algae, but you cannot eat a pocket calculator right? That’s… No really. Basically proteins consist of carbon and hydrogen and nitrogen and there are means to safely degrade them and to turn them into methane or something and you cannot do this with conventional technology,” Bossmann said.

The research has shown that the protein has remained intact throughout testing. MspA is a very sturdy molecule.

“Hooves or horns are better structures—they are very sturdy proteins. Fingernails, things you can scratch people with, and so these structures are really really resistant and therefore we use this kind of material. Of course MspA is only 10x10 nanometers in size so these are very small better bells but you have the same stability like in stable organic structures,” Bossmann said.

The solar cell is a modified Graetzel cell, which is also known as a dye-sensitized solar cell. In Gratzel cells, titanium dioxide is coated with a dye and placed in a solution containing iodide ions. Once sunlight hits the dye, electrons jump from an orbit closer to their nucleus to an orbit where they are be transferred to titanium dioxide. The electrons move from one molecule of titanium dioxide to the next until they jump onto a metal rod submerged in the solution. The electons travel up the rod and through a wire to recharge a battery or power a light. The electrons travel back through a wire to another metal rod submerged in the solution. They then move onto iodide ions which in turn transfer them back to the dye.

In order to incorporate the protein into the design, Ayomi used a less toxic dye. It is also more friendly to living organisms.

“When we developed the cell one of the things that we looked into is to produce a dye which is more compatible with our biodegradable material. We have a dye with a high amount of positive charges which is quite water soluble. It’s something that can be considered greener than the existing technologies which are much more hydrophobic,” Ayomi said.

Solar panels require energy to be produced, most of the time this energy comes from pollution-producing fossil fuels. This means that solar panels must operate for a period of time before they can compensate for the fossil fuel use that produced them. One of the advantages of Graetzel cells is that this period of time is shorter than for traditional solar cells.

“The advantage of the cells that we are doing is that a Graetzel cell needs about a year to produce the energy you need to make it. A normal cell needs two to five years. It’s much harder to produce semiconductors than to produce these Graetzel cells and with the protein which can be grown in bacteria or algae we hope to minimize the energy we need to produce the cell meaning we are earlier in the green,” Bossmann said.

Bossmann also says that solar panels produced from the experimental solar cell likely will not have a higher conversion efficiency than traditional solar panels but will likely produce more net electricity during their lifetime than traditional solar panels.

Currently the solar cell is in the experimental phase and is not yet commercially viable. Ayomi is working on ways to make the cell more efficient. She is also developing a technique to grow the bacteria in a low cost growth medium which would make the cell significantly less expensive to produce.

One of the advantages of their modified Graetzel cell is that the materials needed to produce it are more widely available.

“We have a situation where materials to form high-tech electronics are where and only certain countries like Canada or China or South Africa have the means to find that in the soil. So we try to grow components for electronics which you can grow in a bacterium or an algae so basically in a bucket full of water and some nutrient which makes it available. It’s at some point a question whether everybody has a chance and access to this materials which will become a very very rare commodity and there we see a chance to allow a broad access and especially here in the plain states where we have tones of sun. Definitely the possibility to produce something like that here. It’s an agricultural product if you want so,” Bossmann said.   

That also means that this research has the potential to create jobs in Kansas.

“With such a technology we have much better chance to create jobs over here. Jobs for solar cells will be created in 10 years where you have access to the materials and that won’t be in the U.S. because geologically the US hasn’t. If we can grow proteins which fulfill functions in solar cells then we do have access,” Bossmann said.

The solar cell’s incorporation of a biological component achieves one innovation that was portrayed in the science fiction series Star Trek.

“I mean this is only half serious but watching Star Trek in the 90s the Voyager has some biological components for basically firing of the ship that’s after a 1992 science paper I was on as a post doc. So what we’re doing here basically is a further development with a much more stable organic conductor. The electron jumps to residues on the protein which are designed to host it and then it jumps from place to place and again so bridge the distance between dye and electrode,” Bossmann said.

The research is funded by an Experimental Program to Stimulate Competitive Research (EPSCoR) grant from the National Science Foundation which is funded by Congress.

Ayomi supports renewable energy because fossil fuels are a finite supply and contribute to environmental pollution.

“The consequences of burning fossil fuels are more and more evident: the environmental pollution, the greenhouse effect—global warming and all that. So it’s really crucial that we have an alternate source or sources of energy to compensate for this loss, both in the availability of fuels and in destruction of the environment,” Ayomi said.

Bossmann supports funding for scientific research.

“You have to create a green culture in terms of renewable energy in Kansas and that’s the seed funding. What we do need is a structure where we have support from the state to spin out companies who then sell the stuff. It is important to invest in research infrastructure because you have to conduct your experiments. It’s easy, sometimes not, but usually it is to come up with ideas on paper but you do have to have hard facts to measure this, we are scientists here, not selling off ideas. People ask us what’s the conversion efficiency of your solar cell and of course we should be able to answer that precisely.   And there we would be further along if we would have better investment climate in Kansas,” Bossmann said.

In February Ayomi was named a winner at the Capitol Research Summit in Topeka.

“This summit was an opportunity for students from different universities to go to the capitol building and interact with legislators and present their research. I think it is a tremendous opportunity for graduate student to directly convey to the people who have a hand in funding this research to convey their goals and make them realize the importance of this research. It goes both ways. Even the legislators I mean… they may hear about this research from a 3^rd party but it’s really important to hear it from the scientists actually doing the work so that both parties are informed well,” Ayomi said.

Ayomi received a $500 scholarship from KansasBio for her research. She will discuss the progress of her research with KansasBio in May.

“I enjoy working in this project a lot. I like presenting it and talking about it simply because it’s a very crucial aspect you know alternative energy and it’s important that we do research on it and it’s important we inform people from various fields about the importance of it,” Ayomi said.

After receiving her PhD, Ayomi plans to become a post doctoral fellow in England to increase her knowledge in Chemistry before pursuing a career in alternative energy and biomolecular research. She currently plans to present her thesis in August.

--Jason Beets

h/t Kansas State University News and Editorial Services