Nanostructured Semi-Transparent TiO2 Nanoparticle Coatings Produced by Magnetron-Based Gas Aggregation Source

Abstract

A novel strategy to produce semi-transparent TiO2 nanoparticle-based coatings is investigated. This two-step strategy utilizes a magnetron-based gas aggregation source of Ti nanoparticles that are subsequently annealed in air at the temperature of 450 °C. It is shown that by using this technique, it is possible to fabricate highly porous and patterned TiO2 nanoparticle coatings with an optical band gap of around 3.0 eV on the substrate materials commonly used as transparent electrodes in photovoltaic applications or for water-splitting. In addition, it is shown that the morphology of the resulting coatings may be varied by changing the angle between the direction of the substrate and the incoming beam of nanoparticles. As demonstrated, the tilting of the substrate leads to the formation of columnar nanoparticle films.

Optically Transparent TiO2 and ZnO Photocatalytic Thin Films via Salicylate-Based Sol Formulations

“…The optical bandgaps (E g ) of the TiO 2 and ZnO thin films were determined using the Tauc relation, (αE) n = B E − E g , where α represents the absorption coefficient obtained from transmittance spectra, B is a constant, and E is the photon energy in eV. For indirect bandgap semiconductors like TiO 2 , n = 1 2 [18], while for direct-bandgap semiconductors like ZnO, n = 2 [19,26]. Analysis of (αE) n vs. (E) plots for Ti:10 deposited TiO 2 (Figure 9a), and Zn:10 deposited ZnO films (Figure 9b) revealed E g values of 3.34 eV and 3.3 eV, respectively.…”

“…Transparent TiO 2 and ZnO layers can be fabricated through a variety of deposition methods. Vacuum-based physical vapor deposition (PVD) techniques, such as reactive magnetron sputtering [15,[17][18][19], are commonly favored, however, they can be cost-prohibitive and require specialized equipment and expertise, making them less suitable for smallscale applications. As a result, wet-chemical methods, particularly the sol-gel-based techniques, are preferred, especially in research-scale applications, due to their simplicity, cost-effectiveness, and ability to deposit films without the need for high-vacuum conditions [16,20,21].…”