The effect of mesoporous structure on the thermoelectric properties of nonstoichiometric La-doped SrTiO₃

We investigated the effect of mesoporous structure on the thermoelectric properties of La-doped SrTiO₃ films through the analyses of their structural, electrical, and thermoelectric properties. The mesoporous structure induces a decrease in thermal conductivity and an increase in the Seebeck coefficient because of increased phonon and carrier scattering. The increase of electrical resistivity was smaller than the changes in the Seebeck coefficient and thermal conductivity. As a result, the incorporation of Brij-S10 surfactant into La-doped SrTiO₃ films induced an increase of the figure of merit. The maximum value of the figure of merit-approximately 0.025 at 200°C-was obtained with a Brij-S10 molar ratio of 0.1; this figure of merit was approximately 35% higher than that of a La-doped SrTiO₃ film without the Brij-S10 surfactant. The results of our study suggest that the mesoporous structure could play a role in enhancing the thermoelectric properties.