Team to Research Solar Cell Technology

Two undergraduate physics students, Arihana Roos and Eric Rada, will join professor Jason Stoke, a lecturer in physics at EWU, for a 10-week research project at the National Renewable Energy Laboratory (NREL) in Golden, Colorado.

Their research participation is funded by a federal grant from the U.S. Department of Energy, which covers living costs and research expenses. This grant is awarded as a part of the Visiting Faculty Program (VFP), a collaborative experience in which professors and students partner with a scientist at a national laboratory to conduct research. 

“The way a VFP works is that hopefully you’ll find a scientist at a national lab that is interested in what your skill set is. This program is almost the perfect scenario because it doesn’t cost the scientist anything. It advances their research, and is of minimal time cost,” says Stoke. “We get in there and help them right from day one, and the day-to-day mentoring to the students comes from the professor. I will be the one helping my students.”

David Young, a scientist who specializes in solar cell research at NREL, will oversee the project.

“We’re going to be working on tunnel oxide cells,” says Stoke. These cells are unique, he says, because they have a barrier layer that keeps the different parts of the solar cell separate. Stoke compares these cells to baking a cake. 

“If you have really runny frosting and a spongy cake, eventually that frosting is going to seep down into the cake,” says Stoke. “In a solar cell, it’s kind of the same thing. You want some stuff staying down here, and some stuff staying up there. If you didn’t have this barrier layer, the stuff from the under layer is going to creep up into the upper layer. This buffer layer prevents stuff from creeping where it’s not supposed to be.”

This buffer layer, called the tunneling oxide passivation layer, is a key part in the development of solar cell technology, which is the focus of their research. “The people at NREL are trying to find that sweet spot in terms of making the solar cell just thick enough that it makes a great barrier, but just thin enough that electricity can go through it,” says Stoke. 

Stoke, Rada and Roos will be working to better understand the thin film layers by deploying a technique called “spectroscopic ellipsometry.” Stoke explains that this process uses the reflection of polarized light off of a sample to measure changes in its polarization state. 

“You then use something called an optical model that you think represents the sample. You compare that optical model to what you’ve measured experimentally and hopefully, if it matches, there’s a good chance that your optical model represents the true nature of the sample.”

This research, Stoke believes, could lead to a better solar cell.  “When it comes to solar energy, you want to get the most bang for your buck. You want to have sunlight hitting the solar cells and create the most electrical power that they can from that. You need to make your solar cells cheap enough that people are going to buy them. You also need to make them nontoxic.”

Stoke says he selected Roos and Rada based on classroom evaluation and recommendations. He adds that he was personally impressed with their performance and attention to detail. “I’m very lucky to have these students on the project. I think it’s going to be a great team.” 

For their part, Roos and Rada, say they are looking forward to gaining first-hand experience with this innovative research.

“I am excited to be part of this field of research and am committed to learning as much as I can from the experience,” says Rada, a junior with majors in mechanical engineering and physics. 

Roos, a senior in the physics program, expressed similar excitement about the experiential learning she’ll gain. “I have great personal interest in the field of energy efficiency and renewable energy, so this project is the perfect opportunity for me to learn and grow my skill set,” Roos says.

“This work could revolutionize our nation’s infrastructure and is imperative for our ability to address the challenges of climate change,” says Rada.