In Illinois lab, material shows promise to improve solar panel output

A material used in LEDs could soon be used to boost the output of silicon-based solar panels, and a team including researchers at the University of Illinois Urbana-Champaign is getting closer to putting the pieces together.

Today’s headlines:

🏆 PRIZES: The U.S. Department of Energy announced the first round of winners for its Energy Program for Innovation Clusters prize, including BRITE Energy Innovators in Warren, Ohio; Centrepolis Accelerator in Southfield, Michigan; mHUB in Chicago; and the Combine Incubator in Lincoln, Nebraska.

🖥️ EVENT: BRITE Energy Innovators and Columbus-based 614Startups will host the Ohio Next Energy Summit on Oct. 14, the Youngstown Business Journal reports. Officials from Lordstown Motors Corp. will give the keynote address.

😷 COVID-19: Argonne National Laboratory researchers say they’ve invented the first reusable N95 mask, Built In Chicago reports. A materials science team worked with a California electric vehicle startup and filtration business Donaldson Company to embed antiviral polymers into medical masks.

Now, back to that solar research…

Scientists for decades have known about the potential of gallium arsenide phosphide to complement silicon in solar cells. The semiconductor material has an atomic structure similar to silicon and is likewise effective at converting visible light to electricity, only it does so while producing less heat.

The material is part of a family of compounds known as III-V semiconductors (pronounced “three-five”). They’re stable and established compounds that have been used for years in products including the earliest LED lights. However, they’re also expensive, which is why they haven’t been widely used in solar cells.

The idea to pair these semiconductors with lower-cost silicon has been around since at least the 1980s, but the concept only became technologically possible thanks to advances in the last decade or so. Now, researchers around the world are seeking viable ways to fuse the two together in a single solar cell.

University of Illinois Urbana-Champaign engineer Minjoo Larry Lee leads a team that recently reported significant progress toward that goal. The group has come up with a precisely controlled fabrication process that allows them to place thin layers of gallium arsenide phosphide on top of silicon.

“The idea is working, and it’s getting closer to delivering on its promise,” says Lee.

University of Illinois Urbana-Champaign engineer Minjoo Larry Lee.

The result is a research prototype that shows potential for 1.5 times higher efficiency than a traditional silicon solar cell. If those results can be maintained as they try to find a way to scale it to a commercial product, it would mean 50% more electricity generated using the same amount of land or rooftop space.

The research comes amid a global race to boost the efficiency of solar panels. As silicon solar cells near the limits of their abilities, much of the attention has focused on alternative materials such as III-V semiconductors or perovskites, another promising but less established material generating excitement.

The National Renewable Energy Laboratory is tracking the progress in a tangle of brightly colored lines on its Best Research-Cell Efficiency Chart. (“It’s a very famous graph in my world,” says Lee.) Most commercial solar cells today convert about 15% to 20% of the sun’s energy into electricity. The best efficiency ever achieved was from a different type of experimental solar cell developed in an NREL laboratory that this year set a world-record 47.1% efficiency.

The solar cell Lee’s lab created is considered a tandem solar cell and is not yet included on NREL’s chart but would land in the top tier. Lee estimated they are a year or two behind the best Si-based tandem solar cell in the world, a German cell measured at 29.1% efficiency.

Lee said he’s optimistic about their approach because the materials are both very durable and established. He’s hopeful that as they improve their process, the cost of III-V materials will also come down, noting the growing interest in using them for solar panels in unmanned aerial vehicles.

“We have to find a way to do this that’s cost-effective,” says Lee. “That’s going to be the exciting research over the next few years.”

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