Preparation of Heavily Doped P-Type PbSe with High Thermoelectric Performance by the NaCl Salt-Assisted Approach

Thermoelectric (TE) technology, which can convert scrap heat into electricity, has attracted considerable attention. However, broader applications of TE are hindered by lacking high-performance thermoelectric materials, which can be effectively progressed by regulating the carrier concentration. In this work, a series of PbSe(NaCl)x (x = 3, 3.5, 4, 4.5) samples were synthesized through the NaCl salt-assisted approach with Na+ and Cl− doped into their lattice. Both theoretical and experimental results demonstrate that manipulating the carrier concentration by adjusting the content of NaCl is conducive to upgrading the electrical transport properties of the materials. The carrier concentration elevated from 2.71 × 1019 cm−3 to 4.16 × 1019 cm−3, and the materials demonstrated a maximum power factor of 2.9 × 10−3 W m−1 K−2. Combined with an ultralow lattice thermal conductivity of 0.7 W m−1 K−1, a high thermoelectric figure of merit (ZT) with 1.26 at 690 K was attained in PbSe(NaCl)4.5. This study provides a guideline for chemical doping to improve the thermoelectric properties of PbSe further and promote its applications.