Electrochromism and reversible changes in the position of fundamental absorption edge in cathodically deposited amorphous WO3

Krasnov, Yu. S.; Kolbasov, G. Ya.

doi:10.1016/j.electacta.2004.01.020

Cited by 55 publications

(31 citation statements)

References 40 publications

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“…[1][2][3][4] Thus, various methods used to fabricate WO 3 are reported, such as evaporation, [5][6][7] spray pyrolysis, 8 pulsed layer deposition 9,10 and electrodeposition. 11,12 However, the electrochemical anodization method adopted in this work provides a simple and economic way of synthesizing targeted morphologies such as nanoporous or nanotube structures. Unfortunately there are still drawbacks when compared to vacuum deposited films, for instance the electrochemically prepared WO 3 has poorer reversibility and stability as well as a shorter optical modulation range.…”

mentioning

confidence: 99%

Electrochromic Enhancement of WO₃-TiO₂Composite Films Produced by Electrochemical Anodization

Gui

Blackwood

2014

J. Electrochem. Soc.

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An enhancement of the electrochromic properties of WO 3 thin films by the incorporation of TiO 2 is presented. The composite films are obtained by anodizing co-sputtered tungsten / titanium on conductive glass substrates in 1 M H 2 SO 4 solution containing 0.3 wt% NaF. As the titanium content is increased from 0 to 15 at.% a morphology evolution occurs, from nano-porous to nano-flakes and finally to nano-blocks interweaved with nano-pores. The nano-flakes, obtained at 10 at% Ti, proved to be the most conducive structure for the insertion and removal of Li + ions such that this composition exhibits transmittance regulation abilities of 58.5%, 72% and 77.7% at 550 nm, 632.8 nm and 800 nm respectively, which are more than a 25% improvement at all wavelengths over a pure WO 3 film formed in the same way. The WO 3 /TiO 2 film with addition of 10 at.% Ti also has faster coloration/bleaching times, especially in the critical near infrared region with values of 10 s / 64 s at 800 nm compared with 32 s / 90 s of a pure WO 3 thin film, as well as improved stability losing less than 5% of its capacity after 1000 switching cycles. and electrodeposition. 11,12 However, the electrochemical anodization method adopted in this work provides a simple and economic way of synthesizing targeted morphologies such as nanoporous or nanotube structures. Unfortunately there are still drawbacks when compared to vacuum deposited films, for instance the electrochemically prepared WO 3 has poorer reversibility and stability as well as a shorter optical modulation range. This has led to interest in mixed metal oxide composite systems to compensate for these eficiencies. [13][14][15][16][17][18][19] To date, there are many reports on the doping or mixing other oxides with WO 3 to improve its electrochromic properties, with oxides of barium, 20 cobalt, 21 nickel, 22 molybdenum 23 and most successfully titanium.24 Even a small quantity of the guest oxide has a profound effect on the host's optical properties. Hashimoto and Matsuoka first reported in 1991 that an amorphous WO 3 -TiO 2 film, produced by electron beam deposition method, exhibits a longer life-time than a pure tungsten oxide film. 24 Subsequently, in 1993, Gottsche et al. 25 compared the electrochromic properties of mixed WO 3 -TiO 2 thin films fabricated by sputtering and sol-gel techniques. These authors point out that the addition of TiO 2 with molar percentages ranging from 10% to 15% reduced the crystallinity of WO 3 host and led to significant structural changes. Later, Wang and Hu successfully composed a TiO 2 -doped WO 3 film by spin coating and found that the Ti-addition stabilized the peroxotungstic acid in the spin coating solutions. 26 In 2005, Patil et al. 27 prepared WO 3 -TiO 2 films via a spray pyrolysis method and discussed the improved electrochromic reversibility and coloration efficiency.However, in these earlier works the coloration efficiency has not improved significantly to the level where it can be used in a practical smart window. Indeed, in some cases cert...

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confidence: 99%

Electrochromic Enhancement of WO₃-TiO₂Composite Films Produced by Electrochemical Anodization

Gui

Blackwood

2014

J. Electrochem. Soc.

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“…Для измерения толщины и показателя преломле-ния таких пленок в ходе их роста использо-вался метод двулучевой интерферометрии. Метод основан на одновременной регистра-ции в процессе осаждения пленки двух ин-терферограмм, которые образуются лучами монохроматического света с разными углами падения ψ 1 и ψ 2 [7,8]. Усредненное значение оптического показателя преломления составля-ло n = 1,5, что намного меньше, чем показатель преломления кристаллического оксида никеля (n = 2,37).…”

Section: методика экспериментаunclassified

“…Введенные избыточные электроны (в концентрации порядка 10 21 см -3 ) частично заполняют зону проводимости WO 3 , образованную свободными d-орбиталями ато-мов вольфрама, что сопровождается смеще-нием уровня Ферми по шкале энергий вглубь зоны проводимости и сдвигом в катодном на-правлении электрохимического потенциала оксида [8].…”

Section: экспериментальные результаты и их обсужденияunclassified

OPTICAL MULTISENSOR BASED ON W AND Ni OXIDE FILMS FOR THE DETERMINATION OF CO AND H2 CONCENTRATION

Колбасов¹,

Волков²,

Краснов³

et al. 2014

SEMST

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“…8b). The presence of different phases of WO 3 including triclinic, monoclinic, orthorhombic, and hexagonal [46][47][48] adds to the structural complexity. This inherent disorder, in addition to the lattice polarization effects and electronic structure variation due to the changes in interatomic distances, makes the theory of intercalation more complex than is generally realized.…”

Section: Other Processesmentioning

confidence: 99%

Large cation model of dissociative reduction of electrochromic WO3−x films

Hepel¹,

Redmond²

2009

Open Chemistry

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Studies of dissociative reduction processes of electrochromic WO 3-x films were conducted to: (i) evaluate their utility for electroetching and (ii) determine their fundamental mechanistic features to reduce or eliminate their occurrence in normal optical switching and modulation operation of WO 3-x films. We have found that while the small intercalating cations stabilize WO 3-x structure, the large nonintercalating surfactant cations (Et 4 N+, CtMe 3 N+) contribute to the dissociative reduction. While these cations do not affect WO 3-x structure of anodically protected films (E > 0.2 V), they cause surface lattice polarization on electron injection to the conduction band of WO 3-x at lower electrode potentials, in the absence of intercalating cations. We have found that this process is limited to the surface and no structural damage occurs to the underlying film. The mechanistic aspects of the process have been discussed on the basis of experimental voltammetric and electrochemical quartz crystal nanogravimetric (EQCN) measurements and ab initio quantum mechanical calculations.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.

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Electrochromism and reversible changes in the position of fundamental absorption edge in cathodically deposited amorphous WO3

Cited by 55 publications

References 40 publications

Electrochromic Enhancement of WO₃-TiO₂Composite Films Produced by Electrochemical Anodization

Electrochromic Enhancement of WO₃-TiO₂Composite Films Produced by Electrochemical Anodization

OPTICAL MULTISENSOR BASED ON W AND Ni OXIDE FILMS FOR THE DETERMINATION OF CO AND H2 CONCENTRATION

Large cation model of dissociative reduction of electrochromic WO3−x films

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Electrochromism and reversible changes in the position of fundamental absorption edge in cathodically deposited amorphous WO3

Cited by 55 publications

References 40 publications

Electrochromic Enhancement of WO3-TiO2Composite Films Produced by Electrochemical Anodization

Electrochromic Enhancement of WO3-TiO2Composite Films Produced by Electrochemical Anodization

OPTICAL MULTISENSOR BASED ON W AND Ni OXIDE FILMS FOR THE DETERMINATION OF CO AND H2 CONCENTRATION

Large cation model of dissociative reduction of electrochromic WO3−x films

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Electrochromic Enhancement of WO₃-TiO₂Composite Films Produced by Electrochemical Anodization

Electrochromic Enhancement of WO₃-TiO₂Composite Films Produced by Electrochemical Anodization