Enhancing thermoelectric properties of BiCuSeO via uniaxial compressive strain: First-principles calculations

BiCuSeO as a promising thermoelectric material for medium temperature thermoelectric applications possesses a low lattice thermal conductivity, while its power factor is moderate. In this work, we propose a strategy for enhancing power factor of p-type BiCuSeO via uniaxial compressive strain constraint, based on calculations of electronic structures and thermoelectric properties by using density functional theory and semi-classical Boltzmann transport theory. It is found that the valence band near Fermi level along the Z-Gamma direction becomes steeper, and the slope of the total density of states around the valence band maximum near the Fermi level decreases with an increase in magnitude of compressive strain. All the variations of electronic structures under uniaxial compressive strain lead to an increase of electrical conductivity, resulting in an enhancement of power factor, which is confirmed by our thermoelectric properties calculations. The power factor of p-type BiCuSeO at 900 K can be improved by 11.4% in the case of compressive strain of -6%. Also, the optimal carrier concentrations under different uniaxial strains are identified. (C) 2018 Elsevier B.V. All rights reserved.