Heavy doping and band engineering by potassium to improve the thermoelectric figure of merit in p-type PbTe, PbSe, and PbTe(1-y)Se(y)

Qian Zhang; Feng Cao; Weishu Liu; Kevin Lukas; Bo Yu; Shuo Chen; Cyril Opeil; David Broido; Gang Chen; Zhifeng Ren

doi:10.1021/ja301245b

Heavy doping and band engineering by potassium to improve the thermoelectric figure of merit in p-type PbTe, PbSe, and PbTe(1-y)Se(y)

J Am Chem Soc. 2012 Jun 20;134(24):10031-8. doi: 10.1021/ja301245b. Epub 2012 Jun 7.

Authors

Qian Zhang¹, Feng Cao, Weishu Liu, Kevin Lukas, Bo Yu, Shuo Chen, Cyril Opeil, David Broido, Gang Chen, Zhifeng Ren

Affiliation

¹ Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA.

PMID: 22676702
DOI: 10.1021/ja301245b

Abstract

We present detailed studies of potassium doping in PbTe(1-y)Se(y) (y = 0, 0.15, 0.25, 0.75, 0.85, 0.95, and 1). It was found that Se increases the doping concentration of K in PbTe as a result of the balance of electronegativity and also lowers the lattice thermal conductivity because of the increased number of point defects. Tuning the composition and carrier concentration to increase the density of states around the Fermi level results in higher Seebeck coefficients for the two valence bands of PbTe(1-y)Se(y). Peak thermoelectric figure of merit (ZT) values of ~1.6 and ~1.7 were obtained for Te-rich K(0.02)Pb(0.98)Te(0.75)Se(0.25) at 773 K and Se-rich K(0.02)Pb(0.98)Te(0.15)Se(0.85) at 873 K, respectively. However, the average ZT was higher in Te-rich compositions than in Se-rich compositions, with the best found in K(0.02)Pb(0.98)Te(0.75)Se(0.25). Such a result is due to the improved electron transport afforded by heavy K doping with the assistance of Se.