Researchers have created a solar thermoelectric generator that delivers 15 times the efficiency of the latest leading devices.
Researchers aiming for greater energy independence have investigated solar thermoelectric generators (STEGs) as a way to generate electricity from the sun. Unlike conventional photovoltaic panels, STEGs can harness both direct sunlight and other forms of thermal energy. They feature a hot side and a cold side separated by semiconductors, with the temperature difference producing electricity via the Seebeck effect.
Despite this potential, STEGs have seen limited adoption due to their low efficiency. Most current designs convert less than 1% of incoming sunlight into electricity, compared with around 20% for typical residential solar panels.
University of Rochester Pioneers a Novel Approach
Researchers at the University of Rochester’s Institute of Optics have significantly closed the efficiency gap. In a study published in Light: Science and Applications, they detailed their innovative spectral engineering and thermal management techniques, resulting in a STEG device that produces 15 times more power than earlier models.
“For years, researchers have concentrated on enhancing the semiconductor materials in STEGs, achieving only modest efficiency improvements,” says Chunlei Guo, professor of optics and physics and senior scientist at Rochester’s Laboratory for Laser Energetics. “In this study, we didn’t alter the semiconductor materials at all. Instead, we optimized the device’s hot and cold sides. By improving solar absorption and heat retention on the hot side while enhancing heat dissipation on the cold side, we achieved a remarkable boost in efficiency.”
Three Approaches to Boost Efficiency
The researchers developed their high-efficiency STEGs using three key strategies. On the device’s hot side, they employed a specialized black metal technology from Guo’s lab, which alters standard tungsten to selectively absorb solar wavelengths. By using powerful femtosecond laser pulses to etch nanoscale patterns into the metal’s surface, they enhanced sunlight absorption while minimizing heat loss at other wavelengths.
Next, the team “placed a layer of plastic over the black metal to create a mini greenhouse effect, similar to what’s done in farming,” explains Guo. “This reduces convection and conduction, trapping more heat and raising the temperature on the hot side.”
Finally, on the STEG’s cold side, they applied femtosecond laser pulses to standard aluminum to form a heat sink with microstructures that enhance heat dissipation via radiation and convection, effectively doubling the cooling efficiency of a typical aluminum heat sink.
Potential Applications of High-Efficiency STEGs
In their study, Guo and his team showcased a straightforward demonstration of how their STEGs can power LEDs far more efficiently than existing approaches. Guo notes that the technology could also support wireless sensors for the Internet of Things, supply energy to wearable devices, or function as off-grid renewable power sources in rural regions.
Read the original article on: SciTechDaily
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