engleski

Split-second photothermal processing of thin film titania nanotubes using intense pulsed (white) light

Semiconducting metal oxides (tin oxide, zinc oxide, titanium oxide, indium tin oxide, etc.) have been a hot topic in materials science since the mid-20th century due to their advantageous structural and optoelectrical properties. TiO2, as one of the most researched materials in this group stands out because of its low cost, non-toxicity and excellent chemical and mechanical stability. Also, the plethora of possible TiO2 nanostructures that can be prepared show immense application potential, as nanostructuring of TiO2 leads to an increase in the specific surface area of the material, which in turn increases the efficiency in applications where TiO2 interacts with its environment, e.g. catalysis, sensors, third generation photovoltaics. In addition to the large increase in specific surface area, 1D nanostructures like nanotubes provide superior charge separation and transport due to their ordered structure, elongated shape and thin walls. In most cases, the synthesis routes of ordered TiO2 nanotubes (TNTs) result in amorphous products that require some sort of thermal processing to induce crystallinity. This in term is costly, time-consuming, energy inefficient and limits the final use of the product as all of the components must be thermally stable at the relatively high temperatures of annealing (>450°C). As an alternative approach to the annealing method, we used Intense Pulsed Light (IPL) irradiation as a way to induce crystallinity. The IPL technique induces crystallization by the use of short pulses (µs) of white light without over-heating the substrate. The findings presented in this poster presentation indicate high potential for development of thin film TNTs on flexible plastic substrates that could potentially open up new implementation possibilities for thin film TNTs like flexible solar cells, sensors or photocatalysts, something we will cover in future papers. We have prepared TNTs by anodizing Ti thin films that were deposited using radio frequency magnetron sputtering on FTO (fluorine-doped tin oxide) coated glass substrates and flexible polymer substrates. The as-prepared TNTs were amorphous and with IPL treatment we successfully induced crystalline changes (the formation of anatase with a small amount of rutile). We have tested the parameters of IPL treatment (number of pulses, pulse intensity) in a wide range and optimized them to obtain fully crystalline and transparent TNT layers. Using SEM, XRD, UV-Vis spectroscopy we tracked the changes in surface morphology, crystallinity, opto-electric properties and compared them with the results obtained for the samples annealed in a conventional way in a tube furnace at high temperature.

intense pulsed white light ; TiO2 nanotubes

nije evidentirano