Electron sandwich doubles thermoelectric performance

The ability of thermoelectric materials to convert heat into electricity has been more than doubled. This could help reduce the amount of wasted heat, and thus wasted fossil fuel, in daily activities and industries.

Spread electrons are confined to a narrow space within a superlattice to enhance thermoelectric conversion.

Researchers from Hokkaido University and colleagues in Japan and Taiwan have improved the ability of thermoelectric materials to transform wasted heat into usable electricity by significantly narrowing the space through which spread electrons move.

More than 60% of energy produced by fossil fuels is lost as waste heat. One way to address this problem is to convert the wasted heat into electricity using thermoelectric materials. But improving the conversion rate has been difficult. Thermoelectric materials convert heat into electricity when there is a temperature difference; a phenomenon known as the Seebeck effect. Scientists have been investigating ways to confine electrons to a narrow space to enhance conversion rates. In 2007, researchers built an artificial superlattice composed of ultrathin conducting layers sandwiched between thick insulating layers. This yielded higher voltage but did not improve conversion rates. Researchers have predicted that performance can be significantly improved if widely spread electrons are confined into a very thin conducting layer. But this had not yet been proven experimentally.

The research team, led by Hiromichi Ohta of Hokkaido University, designed a superlattice in which electrons are spread 30% further apart than in previous experiments. This resulted in much higher voltage and doubled the thermoelectric conversion rate recorded from previous methods.

“This is a significant step toward reducing the amount of heat wasted by power plants, factories, automobiles, computers, and even human bodies,” says Ohta.

The study was published in the journal Nature Communications.

For further information, contact:
Professor Hiromichi Ohta
Research Institute for Electronic Science
Hokkaido University
E-mail: [email protected]