US scientists claim 15-fold performance increase for solar thermoelectric generator

A research team have fabricated a solar thermoelectric generator (STEG) that is reportedly 15 times more efficient than current state-of-the-art devices by concentrating on the managing the hot and the cold sides of the device rather than its semiconductor materials.

Scientists from the University of Rochester in the United States have fabricated a solar thermoelectric generator (STEG) that is reportedly 15 times more efficient than current state-of-the-art devices.

A thermoelectric generator (TEG) can convert heat into electricity through the “Seebeck effect,” which occurs when a temperature difference between two different semiconductors produces a voltage difference between two substances. The devices are commonly used for industrial applications to convert excess heat into electricity. However, their high costs and limited performance have thus far limited their adoption on a broader scale.

“Right now, most solar thermoelectric generators convert less than 1% of sunlight into electricity, compared to roughly 20% for residential solar panel systems,” the researchers said, adding that for their commercial scale up lightweight selective solar absorbers (SSAs) and heat dissipators for the STEG hot and cold sides, respectively, are needed.

The novelty of their approach consisted of concentrating on the hot and the cold sides of the device rather than working on the semiconductor materials, as in previous research.

They designed the device with an internally developed special black metal technology that turns shiny metals pitch black. It uses femtosecond laser pulses to transform tungsten to selectively absorb light at the solar wavelengths with reduced heat dissipation at other wavelengths. It is reportedly able to increase thermal electrical generation by 130% compared to untreated tungsten

“We covered the black metal with a piece of plastic to make a mini greenhouse, just like on a farm,” said  the research's lead authour, Chunlei Guo. “You can minimize the convection and conduction to trap more heat, increasing the temperature on the hot side.”

As for the cold side, the scientists also used femtosecond laser pulses on aluminum to create a heat sink with tiny structures that improved the heat dissipation through both radiation and convection.

“When applying both the hot- and cold-side thermal management, with the minimized hot-side radiative and convective heat losses and the enhanced cold side radiative and convective cooling capacity, more solar energy is conducted through and utilized by the STEG,” they stressed. “This results in a greater temperature across the STEG and hence an output power increase of over 15 times while maintaining device compactness with only a 25% increase in weight.”

The system was introduced in the study “15-Fold increase in solar thermoelectric generator performance through femtosecond-laser spectral engineering and thermal management,” published in Light: Science and Applications.

“STEGs could find potential applications in powering avionic devices, wireless sensor networks, wearable electronics, and medical sensors,” the academics concluded.

*The article was amended on August 14 to reflect that the University of Rochester is in the United States, and not in the United Kingdom, as we previously reported.