Low-temperature thermoelectric properties of Pb doped Cu2SnSe3

Abstract A series of Cu 2 Sn 1- x Pb x Se 3 (0 ≤ x ≤ 0.04) compounds was prepared by solid state synthesis technique. The electrical resistivity ( ρ ) decreased with increase in Pb content up to x = 0.01, thereafter it increased with further increase in x (till x = 0.03). However, the lowest value of electrical resistivity is observed for Cu 2 Sn 0.96 Pb 0.04 Se 3 . Analysis of electrical resistivity of all the samples suggests that small poloron hoping model is operative in the high temperature regime while variable range hopping is effective in the low temperature regime. The positive Seebeck coefficient ( S ) for pristine and doped samples in the entire temperature range indicates that the majority charge carriers are holes. The electronic thermal conductivity ( κ e ) of the Cu 2 Sn 1- x Pb x Se 3 compounds was estimated by the Wiedemann-Franz law and found that the contribution from κ e is less than 1% of the total thermal conductivity ( κ ). The highest ZT ~ 0.013 was achieved at 400 K for the sample Cu 2 Sn 0.98 Pb 0.02 Se 3 , about 30% enhancement as compared to the pristine sample.