Journal Article

Broad temperature plateau for thermoelectric figure of merit ZT>2 in phase-separated PbTe0.7S0.3

Pei, Y. L., He, J. Q., Tong, X., Wu, D., Wu, H. J., Kanatzidis, M. G., Zhao, L.-D., Zheng, F. S.

2014

Overview

Thermoelectrics interconvert heat to electricity and are of great interest in waste heat recovery, solid-state cooling and so on. The efficiency of thermoelectric materials depends directly on the average ZT (dimensionless figure of merit) over a certain temperature range, which historically has been challenging to increase. Here we report that 2.5% K-doped PbTe 0.7 S 0.3 achieves a ZT of >2 for a very wide temperature range from 673 to 923 K and has a record high average ZT of 1.56 (corresponding to a theoretical energy conversion efficiency of ~20.7% at the temperature gradient from 300 to 900 K). The PbTe 0.7 S 0.3 composition shows spinodal decomposition with large PbTe-rich and PbS-rich regions where each region exhibits dissimilar types of nanostructures. Such high average ZT is obtained by synergistically optimized electrical- and thermal-transport properties via carrier concentration tuning, band structure engineering and hierarchical architecturing, and highlights a realistic prospect of wide applications of thermoelectrics. Obtaining highly efficient thermoelectric materials relies on a high ZT, and on this value being consistently high over a wide temperature range. Here, the authors demonstrate a phase-separated PbTe-based material that exhibits a ZT of >2 from 673 to 923 K, and a resultantly high average ZT of 1.56 between 300 and 900 K.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 639/301/299/2736 / Energy conversion / Heat recovery / Humanities and Social Sciences / multidisciplinary / Science / Science (multidisciplinary) / Temperature gradients / Waste recovery