Solar Power Reimagined: New “Black Metal” Device Generates 15x More Electricity

Close Up of the High Efficiency STEG — New, high-efficiency STEGs were engineered with three strategies: black metal technology on the hot side, covering the black metal with a piece of plastic to make a mini greenhouse, and laser-etched heat sinks on the cold side. Credit: University of Rochester / J. Adam Fenster

Researchers have developed a solar thermoelectric generator that is 15 times more efficient than the most advanced devices currently available.

Researchers seeking greater energy independence have explored solar thermoelectric generators (STEGs) as a potential way to produce solar electricity. Unlike the photovoltaic cells found in most solar panels, STEGs can capture various forms of thermal energy as well as direct sunlight. These devices consist of a hot side and a cold side separated by semiconductor materials, and the temperature difference between them generates electricity through the Seebeck effect.

However, widespread use of STEGs has been limited by their low efficiency. At present, most models convert less than 1 percent of incoming sunlight into electricity, far below the roughly 20 percent conversion rate achieved by standard residential solar panels.

Innovative approach at the University of Rochester

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.

Close Up of Laser Etched Nanostructures — A close-up of laser-etched nanostructures on the surface of a solar thermoelectric generator. Credit: University of Rochester / J. Adam Fenster

“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.”

Three strategies for efficiency gains

The team designed the new high-efficiency STEGs using three main strategies. For the hot side of the device, they applied a specialized black metal technology developed in Guo’s lab, which modified ordinary tungsten to selectively absorb light at solar wavelengths. By using intense femtosecond laser pulses to etch <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="

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” data-gt-translate-attributes=”[{"attribute":"data-cmtooltip", "format":"html"}]” tabindex=”0″ role=”link”>nanoscale structures into the metal’s surface, they increased its ability to capture energy from sunlight while limiting heat loss at other wavelengths.

Chunlei Guo Tests a Solar Thermoelectric Generator — Rochester researcher Chunlei Guo tests a solar thermoelectric generator (STEG) etched with femtosecond laser pulses to boost solar energy absorption and efficiency. His lab’s innovative black metal technology design helps create a STEG device 15 times more efficient than previous devices, paving the way for new renewable energy technologies. Credit: University of Rochester / J. Adam Fenster

Second, the researchers “covered the black metal with a piece of plastic to make a mini greenhouse, just like on a farm,” says Guo. “You can minimize the convection and conduction to trap more heat, increasing the temperature on the hot side.”

Lastly, on the cold side of the STEG, they once again used femtosecond laser pulses, but this time on regular aluminum, to create a heat sink with tiny structures that improved the heat dissipation through both radiation and convection. That process doubles the cooling performance of a typical aluminum heat dissipator.

Device for Ultrafast Laser Etching of Metal Surfaces — Chunlei Guo uses a laser to generate ultrafast laser pulses that etch nanostructures onto metal surfaces, creating highly efficient STEGs. Credit: University of Rochester / J. Adam Fenster

In the study, Guo and his research team provided a simple demonstration of how their STEGS can be used to power LEDs much more effectively than the current methods. Guo says the technology could also be used to power wireless sensors for the Internet of Things, fuel wearable devices, or serve as off-grid renewable energy systems in rural areas.

Reference: “15-Fold increase in solar thermoelectric generator performance through femtosecond-laser spectral engineering and thermal management” by Tianshu Xu, Ran Wei, Subhash C. Singh and Chunlei Guo, 12 August 2025, Light: Science & Applications.
DOI: 10.1038/s41377-025-01916-9

The National Science Foundation, FuzeHub, and the Goergen Institute for Data Science and Artificial Intelligence supported the research.

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