Synergistic enhancement of thermoelectric performance in n-type PbSe through Sn and Cu co-doping by tuning carrier transport and thermal properties

PbSe is a promising thermoelectric (TE) material with excellent carrier transport properties and an economic advantage due to the lower cost of selenium compared to tellurium, making it a potential alternative to PbTe. Improving its TE performance through dual-element doping represents a widely employed approach. In this study, the TE properties of n-type PbSe are improved through the simultaneous incorporation of Sn and Cu into the PbSe matrix. By precisely controlling the Pb content, we enable Sn dopants to occupy both interstitial sites and substitutional Pb positions, thereby significantly enhancing electrical conductivity. Meanwhile, interstitial Cu exhibits a temperature-dependent dissolution-precipitation behavior, dynamically turning the carrier concentration and improving electrical transport properties. The dual-doping strategy also introduces abundant point defects, effectively scattering phonons and reducing the lattice thermal conductivity. As a result, the electrical transport properties of the co-doped Pb0.99Sn0.01Se-0.7 %Cu sample are further improved by Pb regulation, achieving a power factor of 24.2 mW cm-1K-2 and a peak zT value of 1.80 at 728 K. These results demonstrate the effectiveness of the Sn and Cu co-doping approach in enhancing the TE performance of PbSe, offering promise for the development of cost-effective and high-performance TE materials.