Enhancement of Thermoelectric Efficiency in PbTe by Distortion of the Electronic Density of States
Joseph P. Heremans,1,2*
Vladimir Jovovic,1
Eric S. Toberer,3
Ali Saramat,3
Ken Kurosaki,4
Anek Charoenphakdee,4
Shinsuke Yamanaka,4
G. Jeffrey Snyder3*
The efficiency of thermoelectric energy converters is limited by the material thermoelectric figure of merit (zT). The recent advances in zT based on nanostructures limiting the phonon heat conduction is nearing a fundamental limit: The thermal conductivity cannot be reduced below the amorphous limit. We explored enhancing the Seebeck coefficient through a distortion of the electronic density of states and report a successful implementation through the use of the thallium impurity levels in lead telluride (PbTe). Such band structure engineering results in a doubling of zT in p-type PbTe to above 1.5 at 773 kelvin. Use of this new physical principle in conjunction with nanostructuring to lower the thermal conductivity could further enhance zT and enable more widespread use of thermoelectric systems.
1 Department of Mechanical Engineering, Ohio State University, 201 West 19th Avenue, Columbus, OH 43210, USA.
2 Department of Physics, Ohio State University, 201 West 19th Avenue, Columbus, OH 43210, USA.
3 California Institute of Technology, Pasadena, CA 91125, USA.
4 Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
* To whom correspondence should be addressed. E-mail: heremans.1{at}osu.edu (J.P.H.); jsnyder{at}caltech.edu (G.J.S.)
