Enhanced thermoelectric performance of BiCuSO by Pb doping and Se alloying

Oxysulfides BiCuSO, with a natural superlattice structure, have extremely low thermal conductivity and high Seebeck coefficient. However, the thermoelectric performance of BiCuSO is restricted by its high electrical resistivity resulting from its low carrier concentration and Hall mobility. In this study, BiCuSO was rapidly prepared by one-step high pressure technique. The Pb doping at the Bi site of BiCuSO increases the carrier concentration and decreases the resistivity significantly, which results in an enhanced power factor of ~ 1.0 μWcm⁻¹K⁻² at room temperature for Bi_0.97Pb_0.03CuSO. Meanwhile, substituting Se for S in BiCuSO not only improves the Hall mobility but also decreases the phonon thermal conductivity. Benefiting from the high power factor and low thermal conductivity induced by Pb doping and Se alloying, an enhanced ZT of ~ 0.17 at 673 K is obtained for the sample of Bi_0.97Pb_0.03CuS_0.55Se_0.45O.