Enhancement of Thermoelectric Performance of n-Type PbSe by Cr Doping with Optimized Carrier Concentration

Abstract

Ti, V, Cr, Nb, and Mo are found to be effective at increasing the Seebeck coefficient and power factor of n-type PbSe at temperatures below 600 K. It is found that the higher Seebeck coefficients and power factors are due to higher Hall mobility ≈1000 cm[superscript 2] V[superscript −]1s[superscript −1] at lower carrier concentration. A larger average ZT value (relevant for applications) can be obtained by an optimization of carrier concentration to ≈10[superscript 18]–10[superscript 19] cm[superscript −3]. Even though the highest room temperature power factor ≈3.3 × 10[superscript −3] W m[superscript −1] K[superscript −2] is found in 1 at% Mo-doped PbSe, the highest ZT is achieved in Cr-doped PbSe. Combined with the lower thermal conductivity, ZT is improved to ≈0.4 at room temperature and peak ZTs of ≈1.0 are observed at ≈573 K for Pb[subscript 0.9925]Cr[subscript 0.0075]Se and ≈673 K for Pb[subscript 0.995]Cr[subscript 0.005]Se. The calculated device efficiency of Pb[subscript 0.995]Cr[subscript 0.005]Se is as high as ≈12.5% with cold side 300 K and hot side 873 K, higher than those of all the n-type PbSe materials reported in the literature.