Low temperature synthesis of nanocrystalline WO3 films by sol–gel process

Djaoued, Yahia; Priya, S. Lakshmi; Balaji, S.

doi:10.1016/j.jnoncrysol.2007.07.090

Cited by 56 publications

(30 citation statements)

References 16 publications

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“…All peaks below 200 cm −1 observed in powders B and C are attributed to lattice modes of WO 3 crystalline particles. 52 The lattice modes are absent in A and D.…”

Section: Resultsmentioning

confidence: 99%

Inkjet Printing of Sol–Gel Synthesized Hydrated Tungsten Oxide Nanoparticles for Flexible Electrochromic Devices

Costa

Pinheiro²,

Henriques³

et al. 2012

ACS Appl. Mater. Interfaces

140

112

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Tungsten oxide nanoparticles were synthesized via a sol-gel route using metallic tungsten as precursor, and were printed on a flexible electrode using inkjet printing in order to build solid-state electrochromic cells. Several spectroscopic techniques were used to characterize and compare tungsten oxide particles obtained from different origins. FTIR, Raman and X-ray diffraction spectroscopic measurements showed that the sol-gel synthesis described here produces nanoparticles mainly in an amorphous state with hexagonal crystalline domains and allowed the analysis of the hydration extent of those nanoparticles. The size was measured combining dynamic light scattering, sedimentation, and microscopic techniques (AFM), showing a consistent size of about 200 nm. The tungsten oxide nanoparticles were used to produce an ink formulation for application in inkjet printing. Solid-state electrochromic devices were assembled at room temperature, without sintering the tungsten oxide printed films, showing excellent contrast between on/off states. Electrochemical characterization of those films is described using cyclic voltammetry. The devices were then tested through spectroelectrochemistry by Visible/NIR absorption spectroscopy (400-2200 nm range), showing a dual spectroscopic response depending on the applied voltage. This phenomenon is attributed to the presence of two different crystalline states in accordance with results obtained from the spectroscopic characterization of the nanoparticles. The electrochromic cells had a good cycling stability showing high reversibility and a cyclability up to more than 50,000 cycles with a degradation of 25%.

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“…All peaks below 200 cm −1 observed in powders B and C are attributed to lattice modes of WO 3 crystalline particles. 52 The lattice modes are absent in A and D.…”

Section: Resultsmentioning

confidence: 99%

Inkjet Printing of Sol–Gel Synthesized Hydrated Tungsten Oxide Nanoparticles for Flexible Electrochromic Devices

Costa

Pinheiro²,

Henriques³

et al. 2012

ACS Appl. Mater. Interfaces

140

112

View full text Add to dashboard Cite

show abstract

“…Therefore, such a precursor needs to be aged for a long period of time (3–7days at room temperature or 48 h at 50–60 °C) to obtain a transparent solution indicating that the amount of W 5+ has been minimized 117. The WO 3 films obtained were reported to lack porosity unless a templating method was also used 117, 118…”

Section: Nanostructure Synthesismentioning

confidence: 99%

Nanostructured Tungsten Oxide – Properties, Synthesis, and Applications

Zheng

Strano

et al. 2011

Adv Funct Materials

1,274

911

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This section focuses on the fundamental properties of nanostructured WO x and start with its various crystal structures and the conditions for phase transitions between these structures. The structures of nonstoichiometric WO x and WO 3 hydrates Nanostructured Tungsten Oxide -Properties, Synthesis, and Applications Metal oxides are the key ingredients for the development of many advanced functional materials and smart devices. Nanostructuring has emerged as one of the best tools to unlock their full potential. Tungsten oxides (WO x ) are unique materials that have been rigorously studied for their chromism, photocatalysis, and sensing capabilities. However, they exhibit further important properties and functionalities that have received relatively little attention in the past. This Feature Article presents a general review of nanostructured WO x , their properties, methods of synthesis, and a description of how they can be used in unique ways for different applications.

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“…[9] Synthesis of mesostructured WO 3 using PEG 300 as a structure-directing agent has been reported by Santato et al [10] Recently, we have reported the application of pluronic 123 (P-123) for the low-temperature preparation of mesoporous WO 3 films and demonstrated their electrochromic switching functionality between the bleaching and coloring states. [11] Hauch et al [12] have used organically modified silane (ORMOSIL) as a templating agent for preparing porous layers of titanium oxide (TiO 2 ) and WO 3 for the construction of photoelectrochromic devices. The performance of an EC device depends on the microstructure, crystallinity, crystallite sizes, porosity, and thickness of the electrochromically active layer.…”

Section: Introductionmentioning

confidence: 99%

Micro‐Raman spectroscopic characterization of a tunable electrochromic device for application in smart windows

Balaji

Albert

Djaoued

et al. 2008

J Raman Spectroscopy

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An asymmetric electrochromic (EC) device based on an active EC tungsten oxide-titanium oxide (WO 3 -TiO 2 ) layer was constructed. The EC active layer consisted predominantly of monoclinic WO 3 nanocrystallites with a minor additional component of hexagonal WO 3 and amorphous TiO 2 . Detailed micro-Raman spectroscopic studies of the intercalation and deintercalation of lithium in the EC active layer of the EC device as a function of the applied voltage were performed. Three significant structural stages occur upon intercalating Li into the WO 3 -TiO 2 layer when coloration potentials of 1.0, 1.5, 2.0, and 3.0 V are applied to the EC device. In the first stage (applied potential of 1.0 V), the m-Li x WO 3 phase is retained. In the second stage, (applied potential of 1.5 and 2.0 V) the m-Li x WO 3 transforms to a tetragonal phase. In the third stage, (applied potential of 3.0 V) the Raman spectrum exhibits no spectral bands, showing that Li x WO 3 has attained the highest-symmetry cubic phase. This phase sequence is confirmed by the X-ray diffraction (XRD) measurement. These phase transitions can be reversed and, upon complete deintercalation, m-WO 3 with traces of h-WO 3 is recovered. Optical transmission studies were performed in conjunction with Raman and XRD studies. A shift of the optical transmittance peak position from 639 to 466 nm and reduction in the width of the transmittance curve with increasing applied potential opens up the possibility of smart window applications for the nanocrystalline WO 3 -based EC device.

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Low temperature synthesis of nanocrystalline WO3 films by sol–gel process

Cited by 56 publications

References 16 publications

Inkjet Printing of Sol–Gel Synthesized Hydrated Tungsten Oxide Nanoparticles for Flexible Electrochromic Devices

Inkjet Printing of Sol–Gel Synthesized Hydrated Tungsten Oxide Nanoparticles for Flexible Electrochromic Devices

Nanostructured Tungsten Oxide – Properties, Synthesis, and Applications

Micro‐Raman spectroscopic characterization of a tunable electrochromic device for application in smart windows

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