Synergistic effect of In doping on electrical and thermal properties of Cu2SnSe3 thermoelectric system

Cu 2 SnSe 3 has been considered as a potential thermoelectric material owing to its tunable transport properties and its phonon-glass-electron-crystal (PGEC) characteristics. Here, p -type pure and In-doped Cu 2 SnSe 3 samples are synthesized by the solid-state sintering technique. Cubic structure with F 4 ¯ 3 m space group is maintained for all the samples, and a linear increase in lattice parameter with increasing In concentration has been observed. The nature of electrical resistivity changes from semiconducting to metallic behavior for samples with x > 0.10. The decrease in both electrical resistivity and Seebeck coefficient with an increase in x is attributed to the increased hole concentration. Such a scenario is confirmed from the room-temperature Hall effect measurements. Indium doping also reduces the thermal conductivity of the Cu 2 SnSe 3 system as a result of increased phonon scattering due to the mass fluctuation. Concurrently, enhancement of thermoelectric power factor ( PF ) and figure of merit ( ZT ) is achieved with In doping at Sn site of Cu 2 SnSe 3 . The maximum ZT of 0.04 has been exhibited by the sample with x = 0.25 at 400 K, which is six times higher than that of the undoped Cu 2 SnSe 3 .