Black metal could give a heavy boost to solar power generation
Luke Auburn | Director of Communications, Hajim School of Engineering & Applied Sciences
August 12, 2025

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In the quest for energy independence, researchers have studied solar thermoelectric generators (STEGs) as a promising source of solar electricity generation. Unlike the photovoltaics currently used in most solar panels, STEGs can harness all kinds of thermal energy in addition to sunlight. The simple devices have hot and cold sides with semiconductor materials in between, and the difference in temperature between the sides generates electricity through a physical phenomenon known as the Seebeck effect.

But current STEGs have major efficiency limitations preventing them from being more widely adopted as a practical form of energy production. Right now, most solar thermoelectric generators convert less than 1 percent of sunlight into electricity, compared to roughly 20 percent for residential solar panel systems.

That gap in efficiency was dramatically reduced through new techniques developed by researchers at the University of Rochester’s Institute of Optics. In a study published in Light: Science and Applications, the team described their unique spectral engineering and thermal management methods to create a STEG device that generates 15 times more power than previous devices.

“For decades, the research community has been focusing on improving the semiconductor materials used in STEGs and has made modest gains in overall efficiency,” says Chunlei Guo, a professor of optics and of physics and a senior scientist at Rochester’s Laboratory for Laser Energetics. “In this study, we don’t even touch the semiconductor materials—instead, we focused on the hot and the cold sides of the device instead. By combining better solar energy absorption and heat trapping at the hot side with better heat dissipation at the cold side, we made an astonishing improvement in efficiency.”

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