Intrinsically low thermal conductivity of tetragonal-structured PbSe2

Designing new compounds with earth-abundant constituent elements and intrinsically low thermal conductivity are crucial to the development of thermoelectric materials. In this letter, the tetragonal-structured PbSe2 with extremely low thermal conductivity was prepared by two-step ball milling and high pressure synthesis method. Density functional theory calculation shows that the low thermal conductivity of PbSe2 is originated from its weak interatomic bonding strength and high lattice vibration anharmonicity. We also found that the carrier concentration of PbSe2 can be tuned effectively by Ag doping in Pb site, which leads to an enhanced figure of merit. These results indicate that PbSe2 is a potential candidate as a thermoelectric material.