Synergistic modulation of phonon and charge transport in rare-earth Sm-doped Cu2SnSe3 thermoelectric system

Cu 2 SnSe 3 has attracted a lot of attention as a potential thermoelectric material due to the distinct electrical and thermal characteristics. We report the effect of samarium doping on the Sn site Cu 2 SnSe 3 system. Polycrystalline Cu 2 Sn 1- x Sm x Se 3 (0 ≤ x ≤ 0.08) samples were synthesized by the solid-state method followed by traditional sintering. The low-temperature range of 10–350 K was used to study the electrical transport properties. The lowest resistivity of 0.0024 Ω-cm at 350 K was exhibited by x = 0.08 sample. All the samples’ Seebeck coefficients were found to be positive within the temperature range under investigation, suggesting that most of the charge carriers are holes. With increasing Sm concentration, the resistivity and Seebeck coefficient gradually decreased showing degenerate semi-conducting behaviour. The thermal conductivity also decreased with increasing doping concentration due to the induced defects which enhances the phonon scattering in the Cu 2 SnSe 3 system. Overall, a maximum ZT of 0.017 was achieved for x = 0.08 at 350 K.