Enhancing Thermoelectric Performance of PbSe by Se Vacancies

Abstract

Self-doped n-type PbSe1−δ thermoelectric compounds have been successfully synthesized by the melting and annealing method. The Se vacancies are created by intentionally produced deficiency of Se elements during the sample preparation. Such intrinsic doping can raise the electron concentration to a value as high as 1.2 × 1019 cm−3, leading to greatly improved electrical conductivity and power factor in the n-type PbSe1−δ. Furthermore, the presence of Se vacancies effectively enhances the phonon scattering, resulting in reduced lattice thermal conductivity. Thus, the thermoelectric performance of n-type PbSe1−δ is significantly improved by the formation of intrinsic Se vacancies. The achieved ZT value for the Se-vacancy-rich sample varies from ∼ 0.4 at 330 K to ∼ 1.0 at 675 K, which is comparable to those of the reported n-type PbSe materials with extrinsic doping. In addition, the average ZT of our n-type PbSe system reaches 0.77, which approaches the value of p-type PbTe.