Enhanced thermoelectric performance of n-type PbSe by pyrite FeSe₂ alloying

In this study, the thermoelectric properties of PbSe-x %FeSe₂ (x = 0, 0.25, 0.5, 0.75, 1, 3, 5) alloys are investigated. The results show that FeSe₂ can partly dissolve into the lattice of PbSe to introduce extra holes, which will offset the electron content and reduce the electrical conductivity. Accordingly, the absolute Seebeck coefficient is greatly improved by reducing the electron content. In addition, owing to the reduced electronic thermal conductivity, decreased interatomic force and increased lattice anharmonicity by FeSe₂ alloying, the thermal conductivity of PbSe-0.5 %FeSe₂ is suppressed successfully. Thanks to the improved PF and suppressed κ by FeSe₂ alloying, a larger ZT of 0.53 at 323 K and 1.1 at 773 K with an average ZT of 0.9 are obtained in PbSe-0.5 %FeSe₂.