Enhancement of thermoelectric properties of p-type BiCuSO through strain-induced electronic structures modification

BiCuSO with low thermal conductivity similar to BiCuSeO has little research in the field of thermoelectricity because of its low power factor, although it is cheap and eco-friendly. In this paper, first principles and semi-classical Boltzmann transport theory were made use of studying electronic structures and thermoelectric properties for p-type BiCuSO under biaxial tensile strain, aiming to improve its power factor. The results show that the dispersion of the top valence band decreases along the M-Γ-Z direction under strains, indicating that the Seebeck coefficient of p-type BiCuSO increases. Besides, a detailed analysis of projected density of states found that S 3p and Cu 3d orbitals weakened hybridization with increasing biaxial strain leads to the reduction of electrical conductivity. Thus, the variations of thermoelectric parameters contribute to the increase of power factor for p-type BiCuSO under biaxial tensile strain. Futhermore, the maximum power factor of each strain were estimated at moderate temperatures, and the calculated Seebeck coefficients with different temperatures were compared with experimental data.