Boosting thermoelectric properties of n-type PbS across a broad temperature range through doping with trace amounts of InBi

Lead sulfide (PbS) is a promising thermoelectric material due to its high availability, thermal stability, and cost-efficiency, with research predominantly aiming to enhance its carrier concentration through heavy doping for optimal ZT values at high temperatures. However, this approach often results in suboptimal performance at ambient temperature, significantly constraining its applicability in thermoelectric cooling technologies. In this work, the carrier concentration of n-type PbS is optimized by incorporating trace amounts of InBi. Due to the low carrier concentration, PbS retains a high Seebeck coefficient and carrier mobility, resulting in a high average power factor (PF_ave) of 15.4 μW·cm⁻¹·K⁻² within the temperature range from 300 to 773 K. In addition, the introduction of In/Bi interstitial atoms and dislocation defects enhances phonon scattering, effectively reducing the lattice thermal conductivity of PbS. The peak ZT value of Pb_0.999(InBi)_0.001S at 773 K reaches ∼1.0, while an average ZT value (ZT_ave) of ∼0.6 is achieved between 300 and 773 K in Pb_0.9995(InBi)_0.0005S. This study demonstrates that trace element doping is an effective strategy for optimizing the thermoelectric performance of PbS across a wide temperature range, which is vital in the thermoelectric power generation and refrigeration application.