Promoting p-Type PbS as Efficient Candidates for Thermoelectric Cooling and Power Generation

Thermoelectric technology holds strategic significance in industrial residual heat recovery and solid-state cooling. Nonetheless, the broad implementation of the mainstream Bi₂Te₃-based materials is hindered by tellurium's (Te) low abundance and high expenses. Herein, an economical and abundant p-type lead sulfide (PbS) compound exhibiting remarkable thermoelectric properties is developed. By utilizing a stepwise strategy involving lattice plainification, trace elemental doping, and band engineering, the optimal p-type polycrystal PbS exhibits a maximum ZT value of ≈1.0 at 823 K, while the crystal sample prepared via a temperature gradient method attains an unprecedented room-temperature ZT > 0.4. A novel thermoelectric cooling device is then fabricated utilizing p-type PbS crystal coupled with n-type Bi₂(Te,Se)₃, which demonstrates a maximum cooling temperature difference ∆T_max of ≈52.0 K under a hot-side temperature of 343 K. Furthermore, an all-PbS-based segmented single-leg device is constructed integrating low-temperature crystal with high-temperature polycrystal. This device exhibits an average ZT of ≈0.7 across a wide temperature range (300–823 K). When subjected to a 400 K temperature gradient (ΔT), it achieves a peak efficiency of ≈8.4%. Such advancements highlight the immense potential of PbS thermoelectrics in room-temperature cooling as well as mid-temperature power generation.