For better solar cells, observe the snail

Caren B. Les, caren.les@photonics.com

What do snail teeth and solar cells have in common? A lot more than you might think, if University of California researchers have anything to say about it.

The gumboot chiton uses its exceptionally hard teeth to gnaw on rock to consume algae; because this wears teeth down, the snail’s teeth are replaced continuously in a conveyor-belt kind of motion that constantly brings forward new chompers, on a feeding organ called a radula.

This marine snail, the gumboot chiton, can chew rock. It replaces worn-down teeth in a process referred to as biomineralization. Researchers are working to borrow strategies from the process to develop more efficient and less costly materials for solar panels and batteries.

That regeneration process piqued the interest of advanced materials engineer David Kisailus, an investigator at the University of California, Riverside, who uses systems from nature to inspire his work. His earlier work on abrasion and impact-resistant materials showed that the chiton’s teeth contain magnetite, the hardest biomineral known on Earth.

Now, Kisailus and his group, which includes researchers from Harvard and Chapman universities and from Brookhaven National Laboratory, have investigated the biomineralization process by which the hard and magnetic outer region of the chiton’s tooth formed.

When they studied the growth of mineral within the radular teeth of the chiton, they found that organic fibrils act as templates for the nucleation and growth of mineral, and that the fibrils’ spacing and chemistry play a significant role in determining the size and phase of the resulting mineral. Kisailus said that they will use this information to guide the growth of inorganic materials used in sensitized solar cells.

“Incredibly, all of this occurs at room temperature and under environmentally benign conditions,” he said. “This makes it appealing to utilize similar strategies to make nanomaterials in a cost-effective manner.” Lower-temperature manufacturing methods could translate into lower-cost solar cells.

The findings could affect efficiency, too. Controlling the size, shape and phase of metal oxides using bio-inspired synthetic pathways enables control of some of the limiting features in sensitized solar cells that inhibit their performance, Kisailus said. Currently, sensitized solar cells are about 10 percent efficient in the lab, he noted. “We hope that by controlling the architecture of the nanostructures within the cell, we can double this.”

Kisailus and colleagues are already testing materials for solar panels in the lab. They think that they can scale the material and bring it to market within five years.

The group’s findings, which also could lead to more efficient batteries, are detailed in Advanced Functional Materials (doi: 10:1002/adfm.201202894).