When she came to Brown in 2013, Sophia Gluskin-Braun had no specific interest in solar energy. But a combination of related interests eventually led her to an UTRA research project helping to evaluate a promising new material that could form the basis for the next generation of solar cells.

The engineering concentrator admits that up until junior year of high school, she knew little about what it meant to work as an engineer. That changed when her 11th grade environmental science teacher introduced the class to the field of environmental engineering.

"We learned a bunch of examples of engineering being used to solve environmental problems — which were problems I had cared about my whole life," Gluskin-Braun said. "At the same time I was taking a physics class and I really liked that sort of problem-solving. So I thought I could take this problem-solving method I enjoyed and apply it to problems I really care about."

The final piece of the puzzle fell into place once Gluskin-Braun, now a rising senior, arrived at Brown and fell in love with the fundamentals of light.

"Electricity and Magnetism was my favorite class sophomore year," she said. "From there, I started to get interested in doing research and I found Professor [Domenico] Pacifici, who is an electrical engineer interested in photonics."

In Pacifici's lab, Gluskin-Braun immersed herself in a project exploring the properties of perovskite, a class of crystalline materials that is emerging as a promising component in next-generation solar cells. Perovskite cells can be made for a fraction of the cost of traditional silicon, with nearly the same level of efficiency. Promising as they are, there's still much more work that needs to before they are brought to the mass market.

One of Gluskin-Braun's summer projects, which she worked on with fellow undergraduate Giorgio Savini Zangrandi, was to help characterize the optical and electronic properties of perovskite, including its refractive index, which describes how a material interacts with light. "Determining these properties helps in understanding the absorption properties of the material, which are really important because the whole idea is that you're trying to absorb as much light as possible," Gluskin-Braun said.

Another project centered not on the pervoskite itself, but on the layers surrounding it in a solar cell. Gluskin-Braun and her lab partner looked for ways to deposit tiny metal "nanohole arrays" onto the layers adjacent to the perovskite to create surface plasmon polaritons — current waves created when light energy rattles the free electrons in a metal. Those waves make it possible for light to also travel along the perovskite, allowing for more avenues for absorption and potentially a more efficient cell.

Gluskin-Braun and her teammates made significant progress on these projects over the summer, and they'll continue working on them next semester. One of the most valuable parts of the experience, Gluskin-Braun said, was taking what she had learned in the classroom and putting it into action.

"I was able to use what I'd learned in class right away," she said. "That really made the work fun and gratifying."

by Kevin Stacey