*Joana M. Ribeiro, Filipe C. Correia, Carlos J. Tavares, University of Minho, Guimarães, Portugal
Transparent conducting oxide materials with thermoelectric properties is a promising technology to produce electrical energy through the harvesting of heat from the environment. In this project, TiO₂ (titanium dioxide) thin films doped with Nb (Niobium) were produced by reactive d.c. magnetron sputtering in high vacuum. These films are transparent in the visible region and show promising thermoelectric properties. The goal is to achieve both a high Figure of Merit and Power Factor, by increasing the electrical conductivity, decreasing the thermal conductivity and increasing the Seebeck coefficient of the thin films. Several process parameters were adjusted, such as reactive gas (O₂) partial pressure and deposition time and temperature, which affect the morphology and crystalline structure of the thin films. Hence, by tuning these parameters and modifying the thin film’s optical, electric, thermal and thermoelectric properties enables their suitability for application in photovoltaic systems, touch displays, amongst other devices, in order to render these more sustainable. Results so far show average transmittance in the visible region of up to 85 %, Seebeck Coefficient values of ~-200 µV·K^-1, electrical resistivity of ~10^-2 Ω·cm and thermal conductivity of ~2 W·m^-1·K^-1. These results correspond to a PF of ~10^-4 µW∙K^-2·m^-1 and ZT of 0.1.