Effects of Cl-Doping on Thermoelectric Transport Properties of Cu ₂ Se Prepared by Spark Plasma Sintering

We present the thermoelectric transport properties of Cl-doped Cu ₂ Se _1−x Cl _x (x = 0–0.08) compounds prepared by spark plasma sintering. Cl-doping resulted in a decrease in the electrical conductivity and an increase in the Seebeck coefficient of the compound due to the donor role of Cl. Furthermore, the incorporation of Cl caused the formation of a secondary CuCl phase, which affected the structural, electrical, and thermal properties of the compounds significantly. Although the melting of CuCl limited the operating temperature to ∼ 620 K, the Cl-doped compounds exhibited significantly reduced lattice thermal conductivity because of the presence of the CuCl secondary phase. The highest ZT of 0.6 at 620 K was achieved in Cu ₂ Se _0.92 Cl _0.08 , and the effects of CuCl on the thermoelectric transport properties of Cl-doped Cu ₂ Se _1−x Cl _x compounds are discussed in detail.