High performance of n-type (PbS)_1-x-y(PbSe)_x(PbTe)_y thermoelectric materials

Te-free PbS has been regarded as a promising alternative candidate for PbTe thermoelectric materials due to its advances of low-cost, earth-abundant. In this work, we report an enhanced thermoelectric performance in n-type PbS system arising from synergistically optimized carrier and phonon transport properties. The electrical transport properties are optimized by tuning carrier concentrations via Sb doping, resulting in a maximum power factor of ∼16.7 μWcm⁻¹K⁻² at 623 K, which is approximately tenfold higher than that of undoped PbS (∼1.8 μWcm⁻¹K⁻²). PbSe and PbTe co-alloying in PbS was carried out to reduce lattice thermal conductivity through introducing point defects scattering and second phase, resulting in a minimum lattice thermal conductivity ∼0.71 Wm⁻¹K⁻¹ at 923 K. Combined the enhanced power factor with suppressed thermal conductivity, a maximum ZT value ∼1.0 was obtained in n-type (PbS)_0.53(PbSe)_0.25(PbTe)_0.2Sb_0.02 at 923 K.