The Role of Nanoscale Seed Layers on the Enhanced Performance of Niobium doped TiO2 Thin Films on Glass

Nikodemski, Stefan; Dameron, Arrelaine A.; Perkins, John D.; O’Hayre, Ryan; Ginley, David S.; Berry, Joseph J.

doi:10.1038/srep32830

Cited by 14 publications

(5 citation statements)

References 27 publications

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“…In all of the previously mentioned TiO 2 :Ni 2+ (15 mol %) NPs, longer annealing times (2 h) were employed. However, recent literature reports show that the transformation of amorphous titania into a crystalline anatase phase can be achieved within 30 min of thermal treatment at temperatures as low as 350 °C. , In order to take advantage of this rapid heat treatment for doped TiO 2 , pristine powders of the TiO 2 :Ni 2+ (15 mol %) were rapidly annealed at 450 °C for 30 min. The FTIR spectra (Figure S8a) show that lowering the annealing time from 2 h to 30 min has no effect on the combustion of organic species.…”

Section: Resultsmentioning

confidence: 99%

Effect of Moisture on Dopant Segregation in Solid Hosts

et al. 2019

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Transition metal-doped semiconductor materials are extensively employed for light harvesting and photocatalytic applications owing to their increased light absorption and charge mobility. In this work, spatial tailoring of the Ni dopant in TiO 2 nanostructures is performed by varying the secondary processing parameters to engineer the resulting optoelectronic properties for select applications. Specifically, the aging of the dried Ti sol and the resulting Ni segregation are observed to be moisturedriven phenomena based on the infrared and time-resolved UV−vis spectroscopy measurements. While X-ray diffraction and scanning transmission electron microscopy coupled with electron energy-loss spectroscopy characterizations show a clear difference in the crystal structures between pristine TiO 2 powders and phase-segregated NiO− TiO 2 , the thermogravimetric measurements reveal substitution of the ethoxy group by ambient moisture, resulting in the ejection of hydroxylated Ni clusters. Furthermore, the doped system could be locked into a metastable state by rapidly annealing the amorphous powders. Finally, the photocatalytic activity of these different TiO 2 :Ni 2+ (15 mol %) nanoparticles under AM 1.5G solar light highlights the relationship between the photocatalytic activity and the dopant position. This ability to spatially control dopants within highly doped materials allows for direct control of specific optoelectronic properties, paramount for photoelectrochemical devices.

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Section: Resultsmentioning

confidence: 99%

Effect of Moisture on Dopant Segregation in Solid Hosts

et al. 2019

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“…Since the vibrational spectrum of brookite presents more bands than the other two polymorphs, small amounts of brookite can be detected (Figure 1b) [22]. The more symmetric anatase and rutile structure gives rise to much simpler Raman spectra, with characteristic features evidenced in Figure 1b [23]. Insights into the surface/bulk distribution of phases in a TiO 2 sample can be gained by a combination of common visible/IR Raman with UV Raman spectroscopy, which is more surface-sensitive due to the adsorption of UV light by TiO 2 [24,25].…”

Section: Characterizationmentioning

confidence: 92%

Brookite: Nothing New under the Sun?

2017

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Advances in the synthesis of pure brookite and brookite-based TiO 2 materials have opened the way to fundamental and applicative studies of the once least known TiO 2 polymorph. Brookite is now recognized as an active phase, in some cases showing enhanced performance with respect to anatase, rutile or their mixture. The peculiar structure of brookite determines its distinct electronic properties, such as band gap, charge-carrier lifetime and mobility, trapping sites, surface energetics, surface atom arrangements and adsorption sites. Understanding the relationship between these properties and the photocatalytic performances of brookite compared to other TiO 2 polymorphs is still a formidable challenge, because of the interplay of many factors contributing to the observed efficiency of a given photocatalyst. Here, the most recent advances in brookite TiO 2 material synthesis and applications are summarized, focusing on structure/activity relation studies of phase and morphology-controlled materials. Many questions remain unanswered regarding brookite, but one answer is clear: Is it still worth studying such a hard-to-synthesize, elusive TiO 2 polymorph? Yes.

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“…Interestingly, niobium doping has also been used in several works as an effective way to increase the conductivity of titanium dioxide electron transporting layers 45 or to be used just as alternative transparent conductive oxide. 46 Higher levels of niobium doping in the oleic-acid-stabilised, titanium dioxide (OA-Nb-TiO 2 ) nanorods S4 and S5 resulted in improved leakage current of the dielectric film, mainly by increasing the effective onset voltage of the super-linear regime. Electron-pinned defect-dipoles arising from the interaction between niobium and oxygen vacancies create reduced dielectric losses 44 and could support this interpretation of these results.…”

Section: Device Performancementioning

confidence: 99%