Dual Metal Dopants Advance Near‐Room‐Temperature PbS‐based Thermoelectrics

ABSTRACT Low‐cost lead sulfide (PbS) exhibits poor near‐room‐temperature (300–573 K) thermoelectric performance, limiting its practical applications. Here, Se/Te alloying coupled with dual‐metal Zn/Ge co‐doping is employed to enhance the near‐room‐temperature thermoelectric performance of n‐type PbS. Se/Te alloying forms a single‐phase PbS 0.5 Se 0.35 Te 0.15 solid solution (PbS(Se/Te)), where alloy‐induced mass and strain fluctuations enhance phonon scattering, reducing the lattice thermal conductivity from ∼2.09 W m −1 K −1 for PbS to ∼0.75 W m −1 K −1 at 300 K without compromising electrical transport. Zn/Ge co‐doping further optimizes carrier transport by regulating lattice defects and tuning carrier density, achieving a high carrier mobility of ∼522 cm 2 V −1 s −1 and an optimized carrier density of ∼1.03 × 10 19 cm −3 . The optimized PbS(Se/Te)+0.6‰Zn+5‰Ge sample exhibits an enhanced power factor of ∼20.23 µW cm −1 K −2 at 300 K, yielding a ZT of ∼0.54 at 300 K and an average ZT of ∼0.80 over 300–573 K. A seven‐pair thermoelectric module achieves a maximum temperature difference (Δ T max ) of ∼33.4 K at T h = 343 K, and a single‐leg device reaches a peak conversion efficiency of ∼7.2% under a temperature difference of 300 K. These results highlight the potential of Zn/Ge co‐doping for advancing n‐type PbS‐based materials toward near‐room‐temperature cooling and low‐grade heat recovery.