Thursday, February 12, 2009

Solar Energy from Butterfly Wings?

Everyone believing in clean and green energy knows its drawbacks. Those working on improving solar energy want to improve solar cells’ light harvesting efficiency. So that more and more solar light can be converted into energy. Well, the help may come from butterflies’ wings!

A butterfly’s wing can help us enhancing the solar power efficiency. Butterfly wings have scales that act as tiny solar collectors. Researchers from China and Japan are working on designing more efficient solar cells while taking inspiration from the butterfly wings. If successful, this discovery may lead to powering homes, businesses and other applications in the future.

The conventional cells used in solar cells are dye-sensitized solar cells. They are also known as Grätzel cells after its inventor Michael Grätzel. Chinese and Japanese scientists were trying to improve the efficiency of solar cells by using new materials to improve light-harvesting. They are conducting experiment in dye-sensitized solar cells, which till now have the highest light-conversion efficiencies among all solar cells. Di Zhang and his colleagues ended up turning to the microscopic solar scales on butterfly wings and, using these as a template, made copies of them. These copies were then transferred to the dye-sensitized solar cells. Laboratory tests showed that the butterfly wing solar collectors absorbed light more efficiently than conventional dye-sensitized cells. The fabrication process is less intricate than other methods, and could be used to manufacture other commercially valuable devices, the researchers say.

Tests of these experiments were published in Chemistry of Materials journal. Conclusions from this research indicate that this method of light harvesting can lead to more economical and efficient solar cells in near future. “We studied a novel photoanode structure inspired by butterfly wing scales with potential application on dye-sensitized solar cell in this paper,” reads the abstract of this study. “Quasi-honeycomb like structure (QHS), shallow concavities structure (SCS), and cross-ribbing structure (CRS) were synthesized onto a fluorine-doped tin-oxide-coated glass substrate using butterfly wings as biotemplates separately.”

“Morphologies of the photoanodes, which were maintained from the original butterfly wings, were characterized by scanning and transmission electron microscopies. The results show that the calcined photoanodes with butterfly wings’ structures, which comprised arranged ridges and ribs consisting of nanoparticles, were fully crystallined. Analysis of absorption spectra measurements under visible light wavelength indicates that the light-harvesting efficiencies of the QHS photoanode were higher than the normal titania photoanode without biotemplates because of the special microstructures, and then the whole solar cell efficiency can be lifted based on this.”

Extract from Alternative Energy

http://earthalternate.blogspot.com/2009/02/solar-energy-from-butterfly-wings.html