A convenient sol–gel approach to the preparation of nano-porous silica coatings with very low refractive indices

Zhang, Haoyang; Zhao, Chaoxia; Wang, Pingmei; Ye, Longqiang; Luo, Jia; Jiang, Bo

doi:10.1039/c4cc05397d

Cited by 44 publications

(26 citation statements)

References 18 publications

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“…The most difficult task is to prepare the top layer film with ultra-low refractive index of 1.10. In our previous work, we reported that using MTES and TEOS as co-precursor under base-catalyzed condition could decrease the refractive index of silica film to as low as 1.10 [26], seemingly appropriate to be applied for the designed top layer film. However, the well-adjusted three-layer coating presented a relatively low transmittance of 98.8 % at 355 nm (as seen in Figure S1), too low to meet the rigorous requirement in high-power laser systems.…”

Section: Refractive Index Of Each Layer Of the Three-layer Ar Coatingmentioning

confidence: 99%

Three-layer tri-wavelength broadband antireflective coatings built from refractive indices controlled silica thin films

Zhang

et al. 2016

J Sol-Gel Sci Technol

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A three-layer tri-wavelength broadband antireflective (AR) coating with 100 % transmittance simultaneously at 1064, 532 and 355 nm was designed using TFCalc TM thin film design software. The refractive indices for the bottom, middle and top layers of the designed AR coating are 1.33, 1.21 and 1.10, respectively. To realize the designed AR coating, a template-free sol-gel process was proposed to regulate the refractive index of silica film from 1.09 to 1.44 by simple hybridization. Silica films with refractive index of 1.21-1.44 were prepared by the hybridization of acid-catalyzed silica and base-catalyzed silica, while organically modified silicates films with refractive index of 1.09-1.21 were prepared by the hybridization of tetraethoxysilane, methyltriethoxysilane and hexamethyldisilazane under base-catalyzed condition. These two hybridization methods could conveniently control the porosity, and hence the refractive index of films. Finally, the three-layer tri-wavelength broadband AR coating, which is very important in high-power laser systems, was realized with the transmittance of 99.9, 99.8 and 99.4 % at 1064, 532 and 355 nm, respectively.Graphical Abstract A three-layer tri-wavelength broadband antireflection coating with nearly 100 % transmittance simultaneously at 1064, 532 and 355 nm is designed by TFCalc TM thin film design software and prepared by a simple sol-gel process. A template-free sol-gel process was proposed to prepare silica films with controlled and ultra-low refractive index.

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Section: Refractive Index Of Each Layer Of the Three-layer Ar Coatingmentioning

confidence: 99%

Three-layer tri-wavelength broadband antireflective coatings built from refractive indices controlled silica thin films

Zhang

et al. 2016

J Sol-Gel Sci Technol

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“…Solar energy, among several other alternative energy sources, has been attracting interest in various application elds because of its abundance, cost-effective production, and environmental friendliness. [4][5][6][7] However, to directly fabricate the nanostructures on substrates, nanopatterning (e.g., electron-beam, nanoimprint, or laser interference lithography) and etching processes including chemical and heat treatments are required, which increase the fabrication cost and complexity. [1][2][3] However, the power conversion efficiencies (PCEs) of DSSCs fall below 13%, mainly due to limitations including the light absorption of the dyes and the interface charge separation between dyes and titanium dioxide (TiO 2 ) electrodes.…”

Section: Introductionmentioning

confidence: 99%

Solar power generation enhancement of dye-sensitized solar cells using hydrophobic and antireflective polymers with nanoholes

Lim

Leem

2015

RSC Adv.

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We improve the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) using polydimethylsiloxane (PDMS) patterned with negatively tapered nanoholes (NHs) as a protective antireflection layer of the external glass surface. The NHs PDMS layers are prepared by a soft lithography via silicon molds with conical nanopillars. The NHs PDMS with a NH depth of $320 nm decreases the surface reflection of fluorine doped tin oxide (FTO)-coated glass over a wide wavelength range of 350-800 nm at incident angles (q in ) of 0-70 , exhibiting a lower solar weighted reflectance (R SW ) value of $7.1% at q in ¼ 0 and a lower average R SW value of $8.5% at q in ¼ 20-70 than those (i.e., R SW z 10.1% at q in ¼ 0 and average R SW z 15.6% at q in ¼ 20-70 ) of the FTO glass. In DSSC device applications, it increases the short-circuit current density (J SC ) from 15.69 to 16.52 mA cm À2 , thus resulting in an enhanced PCE value of 7.56% compared to the reference DSSC (i.e., PCE ¼ 7.15%). For different NH depths, the optical reflectance characteristics of the NHs PDMS/FTO glass are theoretically investigated using a rigorous coupled-wave analysis method, showing similar trends between the calculated and measured results. For solar spectrum angle-dependent photocurrents, it also shows a remarkable device performance at q in ¼ 20-70 . Besides, the NHs PDMS exhibits a hydrophobic surface with a water contact angle of $115 .

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“…The image of the SiO 2 ‐solgel (Figure B) displays aggregation morphology which is mainly composed of irregular or flake or nanoparticle units. This morphology can partly be contributed to the formation mechanism of solgel methods . In this work, silica sol which was stabilized by ammonium hydroxide was used as precursor, when adjusting the pH of the solution to 5.5, the free hydroxyl groups begin to dehydrate to form silica sub‐particles or larger molecules, these sub‐particles gradually grow and aggregate and finally come into bigger particles .…”

Section: Resultsmentioning

confidence: 99%

Surface modification of metal mesh with SiO₂ films for enhanced corrosion protection

Zhang

Sai

Guan

et al. 2017

Int J Applied Ceramic Tech

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SiO2 film coatings were used to modify the surface of metal mesh for corrosion protection using liquid phase deposition and sol‐gel methods at low temperature. Different techniques were applied to characterized the as‐prepared samples. The results show an enhanced corrosion protection of the SiO2 deposited samples in comparison to the unmodified samples, as well as the SiO2 deposited sample prepared with sol gel method provides the better corrosion protection when compared with the liquid phased deposited sample, which mainly contributes to its compact morphology. The hydrophobic SiO2 coatings also exhibit excellent corrosion resistance since hydrophobic modification can hinder the contact with environment.

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A convenient sol–gel approach to the preparation of nano-porous silica coatings with very low refractive indices

Abstract: Silica coatings with refractive indices as low as 1.10 were prepared via a one-step base-catalysed sol-gel process using methyltriethoxysilane and tetraethoxysilane as co-precursors. No expensive equipment was required and the method did not require etching or high-temperature calcination.

Cited by 44 publications

References 18 publications

Three-layer tri-wavelength broadband antireflective coatings built from refractive indices controlled silica thin films

Three-layer tri-wavelength broadband antireflective coatings built from refractive indices controlled silica thin films

Solar power generation enhancement of dye-sensitized solar cells using hydrophobic and antireflective polymers with nanoholes

Surface modification of metal mesh with SiO₂ films for enhanced corrosion protection

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A convenient sol–gel approach to the preparation of nano-porous silica coatings with very low refractive indices

Cited by 44 publications

References 18 publications

Three-layer tri-wavelength broadband antireflective coatings built from refractive indices controlled silica thin films

Three-layer tri-wavelength broadband antireflective coatings built from refractive indices controlled silica thin films

Solar power generation enhancement of dye-sensitized solar cells using hydrophobic and antireflective polymers with nanoholes

Surface modification of metal mesh with SiO2 films for enhanced corrosion protection

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Product

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Surface modification of metal mesh with SiO₂ films for enhanced corrosion protection