Cu₂Se as Textured Adjuvant for Pb-Doped BiCuSeO Materials Leading to High Thermoelectric Performance

Exploring the origin of intrinsic low thermal conductivity in BiCuSeO is of great significance for searching new oxide thermoelectric (TE) materials. In addition, from the perspective of material preparation, it is of great value to further develop the TE performance optimization strategy of BiCuSeO-based materials. In this work, the low-temperature TE transport properties of Pb-doped BiCuSeO-based materials are investigated. It is found that Pb doping can greatly optimize the carrier concentration, soften the lattice, and reduce the lattice thermal conductivity. The addition of Cu₂Se significantly enhanced the grain texture and then increased the interface concentration parallel to the pressure direction in the sintering process, which further reduced the lattice thermal conductivity of the material. Finally, the ZT value of Bi_0.96Pb_0.04CuSeO-6 mol % Cu₂Se bulk material is as high as 0.85 at 840 K. This provides important guidance to improve the properties of TE materials via interface engineering.