Enhancing the thermoelectric performance of β-Cu₂Se by incorporating SnSe

Because of its good electrical properties and inherently complex crystal structure, β-Cu₂Se is a potential thermoelectric material. A series of (Cu₂Se)_1−x(SnSe)_x (x = 0, 0.01, 0.03, 0.05, 0.07 and 0.10) alloys were prepared by vacuum melting followed by spark plasma sintering. The X-ray powder diffraction results indicated that a small amount of SnSe dissolved into the β-Cu₂Se structure. The dissolved Sn atoms and the SnSe phase enhanced the power factor and decreased the lattice thermal conductivity of the alloy. The results indicate that introducing an appropriate amount of SnSe into β-Cu₂Se as a secondary phase is an effective approach for improving its thermoelectric performance. At 823 K, the (Cu₂Se)_0.97(SnSe)_0.03 sample exhibited a very high figure of merit (ZT) of 1.41, which is approximately 20% higher than that of the pure β-Cu₂Se sample. - Highlights: • Sn-doping in β-Cu₂Se decreased the resistivity and Seebeck coefficient. • Total and lattice thermal conductivity is decreased. • Power factor is improved. • A high ZT value of 1.41 is obtained at 823 K.