Enhancement of Thermoelectric Efficiency in PbTe by Distortion of the Electronic Density of States
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.
Additional Information© 2008 American Association for the Advancement of Science. Received 28 April 2008; accepted 17 June 2008. This work was supported by the BSST Corporation, the State of Ohio Department of Development's Center for Photovoltaic Innovation of Commercialization (OSU), the Beckman Institute, the Swedish Bengt Lundqvist Minne Foundation, and Jet Propulsion Laboratory, NASA (Caltech). Patent protection related to this work is pending.
Supplemental Material - Heremans_SOM.pdf