Issue 10, 2011

Combining alloy scattering of phonons and resonant electronic levels to reach a high thermoelectric figure of merit in PbTeSe and PbTeS alloys

Abstract

The effect of the resonant impurity Tl, known to produce a high thermoelectric figure of merit in PbTe through a distortion of the density of states (DOS), is explored here in p-type PbTe1−xSx and PbTe1−ySey alloys with direct substitution of Tl for Pb, with the goal of combining its effect with a reduction of the thermal conductivity by alloy scattering. In PbTe1−xSx, the high DOS of PbTe:Tl (x = 0) is maintained up to x = 0.08, whereas the samples' mobility surprisingly increases monotonically with x. An optimal composition is found to reach zT = 1.6 at x = 0.08, using double-doping with both Tl and Na. The DOS of all PbTe1−ySey alloys decreases with y > 0. KKR-CPA electronic structure calculations were performed to enlighten the experimental trends in transport properties: thallium triggers the formation of free-electron-like excess DOS near Fermi level by coupling a Tl 6s-level to the Te p-levels. We ascribe the loss of resonant behavior to a change in overlap between these two levels due to the decrease of the lattice constant with x and y.

Graphical abstract: Combining alloy scattering of phonons and resonant electronic levels to reach a high thermoelectric figure of merit in PbTeSe and PbTeS alloys

Supplementary files

Article information

Article type
Paper
Submitted
05 Jun 2011
Accepted
14 Jul 2011
First published
10 Aug 2011

Energy Environ. Sci., 2011,4, 4155-4162

Combining alloy scattering of phonons and resonant electronic levels to reach a high thermoelectric figure of merit in PbTeSe and PbTeS alloys

C. M. Jaworski, B. Wiendlocha, V. Jovovic and J. P. Heremans, Energy Environ. Sci., 2011, 4, 4155 DOI: 10.1039/C1EE01895G

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