Thermoelectric properties of p-type sb-doped Cu₂SnSe₃ near room and mid temperature applications

In this study, we report low and mid temperature range thermoelectric properties of Sb-substituted Cu₂SnSe₃ compounds. The Cu₂Sn_1−xSb_xSe₃ (0 ≤ x ≤ 0.04) alloys were prepared using conventional solid-state reaction followed by spark plasma sintering. The crystal structure was characterized using XRD and it reveals that all the samples exhibit cubic structure with space group 4 - 3 m. The electrical transport characteristics indicate degenerate semiconducting behavior. Electrical resistivity was found to follow small polaron hopping (SPH) model in the entire temperature range of investigation. The Seebeck coefficient data reveals that the majority of charge carriers are holes and the analysis of Seebeck coefficient data gives negative values of Fermi energy indicating that the Fermi energy is below the edge of valence band. The electronic contribution (κ_e) for total thermal conductivity is found to be less than 1%. The maximum ZT value of 0.64 is observed for the sample with x = 0.03 (at 700 K) which is approximately 2.3 times that of the pristine sample.