High thermoelectric performance of n-type PbTe1−ySy due to deep lying states induced by indium doping and spinodal decomposition

Good thermoelectric materials should have high engineering figure-of-merit (ZT)eng, not peak ZT, to achieve high conversion efficiency. In this work, we achieved a good (ZT)eng by optimizing the carrier concentration to improve the room temperature ZT using deep lying dopant, indium, in PbTe1−ySy. It was found that a room temperature ZT as high as ~0.5 and a peak ZT ~1.1 at about 673K were obtained in Pb0.98In0.02Te0.8S0.2 due to a lower thermal conductivity by alloy scattering and Spinodal decomposition. The calculated efficiency could be as high as ~12% at cold side 323K and hot side 773K. The approach is expected to work in other materials systems too. We have achieved increased average ZT and high conversion efficiency ~12% at cold side 323K and hot side 773K by optimizing the carrier concentration to improve the room temperature ZT using deep lying dopant, indium, in PbTe1−ySy and lowered the lattice thermal conductivity through alloy scattering and Spinodal decomposition. [Display omitted] •PbS was incorporated into In-doped PbTe to increase the electrical conductivity.•Optimization of room temperature ZT by deep lying doping leads to high average ZT.•Thermal conductivity was reduced by alloy scattering and spinodal decomposition.•High conversion efficiency ~12% was achieved at cold side 323K and hot side 773K.