Ti doping effects on the Seebeck coefficient and electrical conductivity of mesoporous ZnO thin film

The low thermal conductivity of mesoporous structures, due to the pores acting as phonon scattering centers, allows their use in thermoelectric devices. However, high Seebeck coefficient and electrical conductivity and low thermal conductivity are required to enhance their thermoelectric properties. In this study, Ti-doped mesoporous ZnO thin films with various Ti concentrations were fabricated and analyzed. When increasing the Ti dopant concentration up to 1.5 at%, the crystallinity and pore structure of the doped films remained almost unchanged, their porosity and thickness slightly increased, the electrical conductivity was also enhanced due to the increased carrier concentration, and the Seebeck coefficient decreased. These Ti doping-induced increase in electrical conductivity and decrease in Seebeck coefficient led to an increase of almost 1.5 times in the power factor of the mesoporous ZnO thin films.