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Sustainability News

ASU Now | February 8, 2020

Zachary HolmanAs we continue to grapple with the adverse effects of climate change, there is a renewed urgency about the need to transition to renewable sources of energy. However, transitioning comes with its own set of challenges, some of which include the high costs of some alternate sources of energy and questions about their efficiency. One renewable source of energy that ticks both of the previous boxes is solar energy.

Solar energy, while quite expensive, still remains one of the most promising sources of alternate energy. It’s why researchers at the Holman Research Group in Arizona State University have been working on innovative ways to reduce its cost. Led by Zachary Holman, an associate professor of electrical engineering and a senior sustainability scientist in the Julie Ann Wrigley Global Institute of Sustainability, the research team has published new findings in the science journal Joule that show how a minute change to the industry-standard silicon wafers significantly enhances solar cell composition.

The change involves combining silicon and perovskites, a class of compounds that efficiently capture light from a different portion of the spectrum than silicon. When perovskites are successfully layered onto silicon wafers in a bifacial cell, they work with different parts of the electromagnetic spectrum to collect and convert more light into electricity than each individual material could collect on their own. This effectively boosts the solar panel efficiency and lowers the cost of energy produced.

The successful creation of the perovskite-silicon tandem cell by Holman’s team and collaborators at the University of North Carolina resulted in 26% efficiency — about a quarter more than current commercial single-absorber (silicon) cells.

“And while that 26% may not sound like much,” Holman said, “companies working in solar fight to secure improvements of even a fraction of a single percent.” So, this advance is notable, and Holman explains that the impact grows as you look beyond the cells or the panels.