Enhancement of thermoelectric performance for n-type PbS via synergy of CuSbS2 alloying and Cl doping

Abstract

Lead sulfide has attracted extensive attention as an outstanding thermoelectric material with practical energy conversion applications at intermediate temperature scope due to its cost-effectiveness and earth-abundant constituent elements. However, the naturally low carrier concentration and high thermal conductivity greatly restrict the thermoelectric performance of PbS-based materials. Herein, we present a significantly promoted thermoelectric performance in n-type PbS through synergistically promoting the electrical conductivity and suppressing lattice thermal conductivity with Cl doping and CuSbS2 alloying. The alloying with CuSbS2 lowers lattice thermal conductivity of PbS, which is essentially ascribed to point defect scattering. While the substitution of Cl for S in lattice significantly increases the Hall carrier concentration and carrier mobility, which prominently boosts electrical conductivity and thus results in high power factor of ~1.38 mW/mK2 at 723 K. Finally, compound with the nominal composition of (PbS0.98Cl0.02)0.95(CuSbS2)0.05 reaches a peak zT of ~0.76 at 773 K.