Synergistically optimizing electrical and thermal transport properties of n-type PbSe

In this paper, we report that the thermoelectric performance of n-type PbSe could be improved through synergistically optimizing electrical and thermal transport properties via Sb doping and Mg alloying. The carrier concentration was firstly optimized through Sb doping, resulting in a maximum power factor of ~ 15.4 μW cm⁻¹ K⁻² and maximum ZT of ~ 0.9 at 873 K in Pb_0.99Sb_0.01Se. Then, Mg was selected for alloying in Pb sites to produce point defects, which can largely intensify the phonon scattering and lower thermal conductivity. After Mg alloying, the thermal conductivity at 300 K (873 K) was significantly suppressed from ~ 4.6 Wm⁻¹ K⁻¹ (1.5 Wm⁻¹ K⁻¹) for Pb_0.99Sb_0.01Se to ~ 2.9 Wm⁻¹ K⁻¹ (1.1 Wm⁻¹ K⁻¹) for Pb_0.99Sb_0.01Se-6%MgSe. Through combining Sb doping and Mg alloying, a maximum ZT of ~ 1.1 was achieved at 873 K for Pb_0.99Sb_0.01Se-6%MgSe, and the average ZT (ZT_ave) was increased by 28.6% from ~ 0.42 for Pb_0.99Sb_0.01Se to ~ 0.54 for Pb_0.99Sb_0.01Se-6%MgSe. The results indicate that PbSe is a robust candidate for medium-temperature thermoelectric applications.