Large Area Fabrication of Periodic TiO<sub>2</sub> Nanopillars Using Microsphere Photolithography on a Photopatternable Sol–Gel Film

Shavdina, Olga; Berthod, Loïc; Kämpfe, Thomas; Reynaud, Stéphanie; Veillas, Colette; Verrier, Isabelle; Langlet, M.; Vocanson, Francis; Fugier, Pascal; Jourlin, Yves; Delléa, O.

doi:10.1021/acs.langmuir.5b01191

Cited by 38 publications

(49 citation statements)

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“…The so-obtained final sol can be coated on glass substrates by spin-coating and is thus compatible with large sized substrates. The deposited sol-gel TiO 2 film is coated by a microspheres monolayer using the Langmuir Blodgett method that leads to hexagonal self-organization of the particles, as detailed in [ 10 ]. Further chemical and optical properties of the sol-gel and details about its preparation, as well as required parameters and details about the photolithographic patterning process can be found in previous works by the authors [ 4 , 10 ].…”

Section: Methodsmentioning

confidence: 99%

“…When TiO 2 sol-gel material, being a negative photoresist, is periodically structured by colloidal lithography, the nanojets issued from each microsphere will lead to the origination of periodic nanopillars [ 10 ]. One limit of this process according to the state of the art is a low aspect ratio (height/lateral size) of the achieved nanopillars (or rods) due to the shape of the nanojet inside the TiO 2 .…”

Section: Introductionmentioning

confidence: 99%

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Periodic TiO2 Nanostructures with Improved Aspect and Line/Space Ratio Realized by Colloidal Photolithography Technique

et al. 2017

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This paper presents substantial improvements of the colloidal photolithography technique (also called microsphere lithography) with the goal of better controlling the geometry of the fabricated nano-scale structures—in this case, hexagonally arranged nanopillars—printed in a layer of directly photopatternable sol-gel TiO2. Firstly, to increase the achievable structure height the photosensitive layer underneath the microspheres is deposited on a reflective layer instead of the usual transparent substrate. Secondly, an increased width of the pillars is achieved by tilting the incident wave and using multiple exposures or substrate rotation, additionally allowing to better control the shape of the pillar’s cross section. The theoretical analysis is carried out by rigorous modelling of the photonics nanojet underneath the microspheres and by optimizing the experimental conditions. Aspect ratios (structure height/lateral structure size) greater than 2 are predicted and demonstrated experimentally for structure dimensions in the sub micrometer range, as well as line/space ratios (lateral pillar size/distance between pillars) greater than 1. These nanostructures could lead for example to materials exhibiting efficient light trapping in the visible and near-infrared range, as well as improved hydrophobic or photocatalytic properties for numerous applications in environmental and photovoltaic systems.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Periodic TiO2 Nanostructures with Improved Aspect and Line/Space Ratio Realized by Colloidal Photolithography Technique

et al. 2017

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“…These two processes enable us to make large TiO 2 -based diffraction gratings. The whole sol-gel process has been detailed in previous papers [14,18], as well as the DIL process [16,17]. Both processes will be briefly described hereafter.…”

Section: Grating Fabrication and Experimentsmentioning

confidence: 99%

“…The technology presented in this paper focuses on diffraction gratings placed on the top of the glass cover to deflect the light to the cell directly or by Total Intern Reflection (TIR). The gratings are made by dynamic interferometric lithography (DIL) onto a TiO 2 xerogel thin film, with a technology developed in our laboratories [14][15][16][17][18]. This technology allows fabricating long and large diffraction gratings directly on a robust material with very interesting optical properties for diffraction gratings.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Interferometry Lithography on a TiO₂Photoresist Sol-Gel for Diffracting Deflector Module

Gâté

Berthod

Langlet

et al. 2017

Journal of Nanomaterials

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Solar electricity is one of the most promising renewable energy resources. However, the ratio module’s cost/energy produced remains a major issue for classical photovoltaic energy. Many technologies have been developed to solve this problem, by using micro- or nanostructuring on the solar cell or on the module. These kinds of structuring are often used as antireflection and light-trapping tools. In the meantime, other solar technologies are considered, such as concentration photovoltaic modules. This article presents a module combining both approaches, that is, nanostructures and concentration, in order to increase the module’s profitability. Sol-gel derived TiO2diffraction gratings, made by dynamic interferometric lithography, are added on the top of the glass cover to deflect unused light onto the solar cell, increasing the module efficiency.

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“…Finally, microsphere lithography-shown in Figure 1(d)-was used to print a hexagonal array of TiO 2 nanopillars. 4 In this method, a layer of silica microspheres is deposited on the sol-gel photoresist in a hexagonal arrangement. Each of the microspheres acts as a convergent super-lens to create a photonic nanojet (i.e., a highly focused, high-intensity light beam) and, after development, the nanopillar array.…”

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confidence: 99%

A new sol-gel process for fabricating TiO2 photoresists

Jourlin¹,

Berthod²

2017

SPIE Newsroom

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A simple and cost-effective sol-gel method produces stable titanium dioxide and titanium oxynitride photoresists, and is compatible with many photolithographic techniques.Titanium dioxide (TiO 2 ) is a globally important material with a wide range of applications, including in the paint, cosmetics, and food industries. The microstructure of one of the mineral forms of TiO 2 , anatase, gives the material useful properties such as light trapping and photocatalysis, and hence anatase is of particular interest in optics and photonics research. This form of TiO 2 can be synthesized using a sol-gel method-a process in which a colloidal solution of a molecular precursor is converted to a network polymer-producing a material with excellent mechanical and chemical stability over long periods of time.Here, we present the results of our research developing a sol-gel to fabricate simple and cost-effective TiO 2 photoresists for photolithographic applications. 1 Photoresists are light-sensitive materials used to fabricate patterned thin films on the microscale or sub-microscale (i.e., photolithography). There is a large range of photolithographic techniques available, and our sol-gel is compatible with a number of these. Compared with other photoresists, the increased stability of the patterned TiO 2 thin films produced using this precursor means no post-processing (e.g., lift-off processes or etching) is required. Moreover, the density of the resulting TiO 2 thin film can easily be adjusted with heat treatment to create a dense material with a high refractive index of up to 2.2. Without heat treatment, the material is porous with a low refractive index.Our sol-gel TiO 2 photoresist fabrication method is a fivestep process. Initially, titanium tetraisopropoxide is polymerized in a mixture of methanol and butanol, producing an alcohol-insoluble (TiO) n network material. Alcohol-soluble benzoylacetone (BzAc) is added, which forms a complex with the titanium, resulting in a sol-gel. A film of the sol-gel is then deposited on a substrate. BzAc is very sensitive to UVA light, and hence when areas of the sol-gel film are exposed to UV Figure 1. Examples of four different photolithographic techniques. (a) Laser interference lithography, (b) dynamic interferometric lithography, (c) radial phase-mask lithography, and (d) microsphere lithography. TiO 2 : Titanium dioxide. BzAc: Benzoylacetone. Â: Angle between laser arms. d: Depth. : Period. -spheres: Microspheres. Continued on next page

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Large Area Fabrication of Periodic TiO₂ Nanopillars Using Microsphere Photolithography on a Photopatternable Sol–Gel Film

Cited by 38 publications

References 40 publications

Periodic TiO2 Nanostructures with Improved Aspect and Line/Space Ratio Realized by Colloidal Photolithography Technique

Periodic TiO2 Nanostructures with Improved Aspect and Line/Space Ratio Realized by Colloidal Photolithography Technique

Dynamic Interferometry Lithography on a TiO₂Photoresist Sol-Gel for Diffracting Deflector Module

A new sol-gel process for fabricating TiO2 photoresists

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Large Area Fabrication of Periodic TiO2 Nanopillars Using Microsphere Photolithography on a Photopatternable Sol–Gel Film

Cited by 38 publications

References 40 publications

Periodic TiO2 Nanostructures with Improved Aspect and Line/Space Ratio Realized by Colloidal Photolithography Technique

Periodic TiO2 Nanostructures with Improved Aspect and Line/Space Ratio Realized by Colloidal Photolithography Technique

Dynamic Interferometry Lithography on a TiO2Photoresist Sol-Gel for Diffracting Deflector Module

A new sol-gel process for fabricating TiO2 photoresists

Contact Info

Product

Resources

About

Large Area Fabrication of Periodic TiO₂ Nanopillars Using Microsphere Photolithography on a Photopatternable Sol–Gel Film

Dynamic Interferometry Lithography on a TiO₂Photoresist Sol-Gel for Diffracting Deflector Module