Transparent niobium-doped titanium dioxide thin films with high Seebeck coefficient for thermoelectric applications

This work reports the production and characterization of optically transparent Nb-doped TiO2 thin films with enhanced thermoelectric properties deposited on glass and Si by reactive d.c. magnetron sputtering in high vacuum. The purpose of these films is to harvest thermal energy from the environment...

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Bibliographic Details
Published in:Surface & coatings technology 2021-11, Vol.425, p.127724, Article 127724
Main Authors: Ribeiro, J.M., Correia, F.C., Rodrigues, F.J., Reparaz, J.S., Goñi, A.R., Tavares, C.J.
Format: Article
Language:English
Subjects:
Direct current
Energy harvesting
Figure of merit
Flow velocity
Gas flow
High vacuum
Magnetic properties
Magnetron sputtering
Niobium
Optical properties
Optimization
Photovoltaic cells
Power factor
Process parameters
Seebeck effect
Thermal conductivity
Thermal energy
thermoelectric
Thermoelectricity
Thickness
thin film
Thin films
TiO2
Titanium dioxide
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Summary:This work reports the production and characterization of optically transparent Nb-doped TiO2 thin films with enhanced thermoelectric properties deposited on glass and Si by reactive d.c. magnetron sputtering in high vacuum. The purpose of these films is to harvest thermal energy from the environment and convert it to electrical energy. Several process parameters, such as reactive and working gas flow rate, deposition temperature, target current density and post-annealing conditions, directly affect the morphology and crystalline structure of the thin films. The optimization of these parameters results in thin films with thickness of 120–300 nm, maximum average optical transmittance in the visible range of 73%, n-type electrical resistivity of 0.05 Ω·cm, thermal conductivity around 1.5 W·m−1·K−1 and a maximum absolute Seebeck coefficient of 223 μV·K−1. The resulting maximum thermoelectric power factor is 60 μW·K−2·m−1 and the maximum thermoelectric figure of merit is 0.014. Hence, modifying the optical, electric, thermal and thermoelectric properties of the thin films enables their suitability for applications as transparent electrodes in photovoltaic systems and touch displays, amongst other devices. [Display omitted] •Absolute Seebeck coefficient >200 μV/K attained for transparent films•Power factor of 60 μW·K−2∙m−1 and ZT = 0.014 achieved for optimized thin films•Anatase and rutile crystalline phases enhance thermoelectric property.•Applicable for thermal energy harvesting in transparent devices
ISSN:0257-8972
1879-3347
DOI:10.1016/j.surfcoat.2021.127724