First principles studies on the thermoelectric properties of (SrO)m(SrTiO3)n superlattice

Abstract

The electronic structures and thermoelectric properties of (SrO)_m(SrTiO₃)_n superlattices have been investigated using first-principles calculations and the Boltzmann transport theory. Due to the much reduced dispersion along the c-axis, the thermoelectric properties for n-type superlattices are found to be highly anisotropic with the in-plane electrical conductivity with respect to relaxation time much higher than the out-of-plane one. The reduction of the in-plane Seebeck coefficient compared with SrTiO₃ results in a slightly reduced power factor with respect to relaxation time for n-type doped (SrO)_m(SrTiO₃)_n. However, both Seebeck coefficient and electrical conductivity with respect to relaxation time are relatively maintained for p-type doping, leading to a comparable power factor with respect to relaxation time. If the reduced thermal conductivity is taken into account, an improved ZT value can be expected for the (SrO)_m(SrTiO₃)_n superlattice.