Realizing Broad-Range Thermoelectric Performance in PbS through Distorting Rock-Salt Lattice
Lattice distortion via entropy engineering can significantly optimize thermoelectric performance by intensifying phonon scattering. However, excessive lattice distortion in high-entropy materials inevitably hinders carrier transport, limiting the wide-temperature average ZT (ZTave). To enhance the wide-temperature thermoelectric performance of low-cost PbS-based compounds, this work introduces moderate lattice distortion by controlling entropy around 1.0R (R is the gas constant) to balance phonon and carrier transport, alleviating restrictions on carrier mobility. Substantial Se and Te alloying in PbS induces rock-salt lattice distortion, effectively impeding phonon propagation, thus suppressing lattice thermal conductivity (κlat) from 2.41 W m−1 K−1 in PbS to 0.66 W m−1 K−1 in PbS0.5Se0.35Te0.15 at 300 K. Additionally, Cu interstitials are introduced into the lattice-distorted PbS0.5Se0.35Te0.15 to further optimize carrier density and weighted carrier mobility (μW), leading to significant improvement in μW/κlat parameter at 300–773 K. Finally, a room-temperature ZT of 0.53 and a maximum ZT of 1.44 are obtained in PbS0.5Se0.35Te0.15-1%Cu sample, contributing to an impressive ZTave of 1.08 at 300–773 K and a maximum power generation efficiency (ηmax) of 7.5%. The results outperform previously reported cost-effective PbS-based compounds and highlight the importance of lattice distortion regulation in enhancing wide-temperature thermoelectric performance.