Nanotechnology boosts thermoelectric effect

Thermoelectric coolers and power generators were handed a 40-percent boost in performance recently by a nanotechnological reconstruction of a classic bulk material. The technique is suitable for mass production, according to its inventors at Boston College and the Massachusetts Institute of Technology (MIT). This makes it of use in both industrial and consumer cooling applications from semiconductors to nanoscale power generators.

"Thermoelectric materials are already used in many applications," explains MIT professor Gang Chen, "[b]ut our more efficient nanoscale material will give a big boost to their performance."

The material improved by the researchers was bismuth antimony telluride, a common bulk semiconductor that has been used since the 1950s. It is used in a variety of applications from generating power for remote spacecraft at the National Aeronautics and Space Administration (NASA) to cooling automobile seats during summer heat waves. The auto industry has also been experimenting with ways of converting the heat from can exhausts into electric current that charges the batteries of hybrid cars.

Now all these applications, and even more, could be boosted by a process in which bulk bismuth antimony telluride is pulverized into nanoparticles as small as five nanometers before being reconstituted into a bulk material, bringing with it a 40-percent efficiency gain.
"Our technique is a low-cost method that can be easily scaled for mass production," said Boston College professor Zhifeng Ren. "Nanotechnology has enabled us to improve an old material by breaking it up and then rebuilding it into a composite of nanostructures in bulk form."

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Also contributing to the work were MIT Professor Mildred Dresselhaus, Boston College research scientist Bed Poudel and CEO Mike Clary of GMZ Energy, Inc. (Newton, Mass.), as well as Boston College visiting professor Junming Liu and a visiting physicist from Nanjing University (China). The research was funded by the Department of Energy and the National Science Foundation.