Wu Group Study Shows Defects Can “Hulk- Up” Materials

(From left) Joonki Suh, Wladek Walukiewicz and Junqiao Wu (Photo by Roy Kaltschmidt)

(From left) Joonki Suh, Wladek Walukiewicz and Junqiao Wu (Photo by Roy Kaltschmidt- Berkeley Lab)

As the exposure to gamma radiation transformed scientist Bruce Banner into the Hulk, exposure to alpha-particle radiation, has shown to “Hulk-Up” certain thermoelectric materials, transforming them into more powerful versions of themselves. When properly managed, a damaged thermoelectric material’s performance can be enhanced by a factor up to ten.

The ability of thermoelectric materials to convert either heat into electricity, or electricity into cooling, means a potentially large source of clean, green energy. Past studies have shown that the efficiency of heat-to- electricity conversion, measured as ZT, is limited by the coupling of thermopower, thermal conductivity, and electrical conductivity; Normally, when thermopower is enhanced, it causes a reduction of electrical conductivity. But, in this study, the Wu group has found a way to break this coupling, demonstrating an increase in both electrical conductivity and thermopower. By exposing thin-films of bismuth telluride, a well-characterized thermoelectric, to alpha-particles, Wu and his group have achieved the highest ZT rating ever recorded for bismuth telluride at room temperature, a value of 1.24. They believe their technique can also be used to improve the ZT values of other thermoelectric materials.

A paper titled “Simultaneous Enhancement of Electrical Conductivity and Thermopower of Bi2Te3 by Multi-Functionality of Native Defects” with lead author Joonki Suh, has been published in Advanced Materials. 

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