Greener Solar Power With Help From Bacteria

Solar cells made with biodegradable components are extremely rare. Ayomi Perera, a Kansas State University doctoral student, created dye-sensitized solar cells out of a protein produced by bacteria and a dye less toxic than traditional dyes. This attractive new research might make solar power even greener.

Dye-sensitized solar cells have been around for decades, and although production is affordable, a few problems burden their potential. Their energy conversion efficiency is only about 11 percent. In the standard p-n junction photovoltaic cells, advances in technology have enabled commercial production of cells with efficiencies upward of 20 percent. In general, dye-sensitized cells continue to improve in efficiency and design, but Perera decided to focus on another problem—the dyes and solvents commonly used in dye-sensitized solar cells can be toxic to people and the environment.

Perera poster

image via Kansas State University

Based on the principle of photosynthesis, the process in which plants convert sunlight into food, modern dye-sensitized cells are made of conductive glass with a porous layer of titanium dioxide nanoparticles covered in a molecular dye. The dye absorbs sunlight just as chlorophyll does in plants. With immersion in an electrolyte solution (often a corrosive material), a platinum-based catalyst adds the final component necessary to create electricity via the dye-sensitized cells.

Perera turned to bacteria for help in creating a less toxic version. Under the guidance of Professor Stefan Bossmann, Perera investigated the bacteria Mycobacterium smegmatis. The strain is relatively safe and easy to grow. It produces MspA, a protein which, when purified, has “so many applications due to its interesting surface chemistry,” according to Perera. Production of solar cells with a protein component became the focus of her research. The protein is mixed with an environmentally friendly dye, and a coat of the mixture is applied to the solar cells. Sunlight hits the dye, which produces electrons, and the protein transfers them in one direction, creating an electric current.

Based in New York City, Leah Jones is a freelance writer with undergraduate degrees in criminal justice and forensic science. She has worked on research in the toxicology field for several years, and she brings her passion for science into the realm of green technology with EarthTechling. Leah has studied English at the graduate level and has authored or co-authored over 30 publications in scientific journals. When she's not writing, Leah enjoys playing music with her husband and teaching music to New York City kids.