Enhanced Thermoelectric Properties of Cu3SbSe4 Compounds via Gallium Doping

In this study, the p-type Ga-doped Cu3Sb1−xGaxSe4 compounds were fabricated by melting, annealing, grinding, and spark plasma sintering (SPS). The transport properties of Ga-doped Cu3Sb1−xGaxSe4 compounds were investigated. As Ga content increased, the hole concentration of Cu3Sb1−xGaxSe4 compounds increased, which led to an increase in electrical conductivity. Meanwhile, the Seebeck coefficient of the Cu3Sb1−xGaxSe4 compounds decreased as Ga content increased. The extra phonon scattering originating from Ga-doping effectively depressed the lattice thermal conductivity of the Cu3Sb1−xGaxSe4 compounds. The ZT value of Cu3SbSe4 markedly improved, which is primarily ascribed to the depressed lattice thermal conductivity and the increased electrical conductivity. The highest ZT value for the Cu3Sb0.985Ga0.015Se4 compound was 0.54 at 650 K, which is two times higher than that of a pure Cu3SbSe4 compound.