16 April 2012
A doctoral student in chemistry at Kansas State University, Manhattan, Kansas (US) has created the first-ever environmentally friendly dye-sensitized solar cell (DSSC), incorporating a protein extracted from a bacterium called Mycobacterium smegmatis.
Originally from Colombo, Sri Lanka, Ayomi Perera came to Kansas State to pursue her Ph.D. in Chemistry under Dr. Stefan Bossmann, professor of chemistry. Knowing well that “the impact of using fossil fuels has drastic consequences for the environment,” and that “it also is no secret that the availability of fossil fuels will be greatly limited in the near future,” Perera says she felt inspired not merely to study a sustainable source of energy, but to go further and research a greener solar cell altogether. “This research would introduce an entirely new dimension to the future of DSSC research as a renewable, biodegradable DSSC has not been invented before,” the student says.
But couldn’t any solar cell be considered “green”, considering it is outputting renewable energy? Perera says no. When it comes to DSSC, most commerzially available dyes “cannot be classified as environmentally friendly,” she argues. “Since we are attempting to create a technology with the least adverse environmental impact, it made sense to investigate a new class of dyes that is less toxic.”
Essentially, Perera created a DSSC “incorporating a protein extracted from a bacterium called Mycobacterium smegmatis, a channel forming protein (porin), which is extremely stable against high temperature, organic solvents and extreme pHs,” she explains. “We have chemically bound a Ruthenium-phenanthroline dye to a mutant form of the protein. The protein-dye complex is adsorbed onto a surface with titanium dioxide nanoparticles and, subsequently, can be used in electrochemical experiments to investigate photocurrent conductance.”
Perera doesn’t just want a greener solar cell. She also wants DSSC technology to be “economically viable, not only in countries like the US, but everywhere on the globe.” And her novel protein-incorporated cell fits that bill. “DSSC components that can be grown in bacteria or algae will be available everywhere, precious metals won’t,” she says. “Introducing a technology that is renewable will foster the production of solar cells in every country, not only the countries that have resources for the production of inorganic components for solar cell fabrication.” What’s more, her cell has the advantage of being biodegradable once it reaches the end of its lifecycle.
The Ph.D. student has reason to be confident in her invention. “We have demonstrated that a current is generated via the protein-dye complex when exposed to a solar simulator with an overall conversion of 1% light into current,” Perera says. “The protein shows no evidence of decomposition throughout the experiment and 'current switching' in light and dark conditions can be successfully demonstrated. These are the reasons that tell us that we have a working solar cell.”
The next step for Perera is to improve the overall efficiency of her dye-sensitized solar cell. She plans to introduce a new surface that “can better accommodate the large protein-dye complex.” She also wants to “be able to control the orientation of the complex to obtain maximum exposure of dye molecules to sunlight while attaining maximum binding of proteins per unit area of absorbent.” Her team is looking into indium-tin-oxide surfaces as a viable option. “Our future prospects include introducing algae as the biodegradable component in the cell, as it is a low-cost, highly renewable source of biomaterial,” Perera says.
If her technology can be applied commercially, she hopes, “it would introduce a new class of solar cells as a sustainable green energy source.”
Written by Sandra Henderson, Research Editor, Solar Novus Today