Thermoelectric Transport Characteristics of n-type (PbTe)_1-x-y(PbS)_x(Sb₂Se₃)_y Systems via Stepwise Addition of Dual Components

Abstract

PbTe recently attracted extensive attentions as potential candidates for applications at intermediate temperatures. However, it is difficult to significantly improve the thermoelectric performance of ntype PbTe due to its relatively low carrier concentration and complicated band structures. In this study, the stepwise addition of dual components was utilized to verify the possibility for modulating the thermal and electrical transport characteristics of n-type PbTe-based materials. The results indicated that PbS and Sb2Se3 can improve the power factor and reduce thermal conductivity of PbTe, respectively. Optimization of band structures and enhancement of phonon scattering were realized by means of expanding band gap, producing point defects and secondary dispersoids. As a result, the merit of figure ZT was remarkably improved. In particular, (PbTe)0.94(PbS)0.05(Sb2Se3)0.01 exhibited the highest value of ZT=1.7 at 700 K simultaneously with almost doubled average ZT compared to the pristine PbTe. Accordingly, it seems that the stepwise addition of adequate dual components provides possible technological approach for improving thermoelectric performance of other materials.