New Solution Route to Electrochromic Poly(acrylic acid)/WO₃ Hybrid Film

Abstract

Electrochromic tungsten oxide film was fabricated by a new soft chemistry route, in which the transparent conducting glass substrate was successively dip-coated with poly(acrylic acid) (PAA) and ammonium tungstate solutions. The as-coated composite layer of PAA/(NH 4 ) 2 -WO 4 ‚nH 2 O was dried at a low temperature (100 °C), and the ammonium tungstate component was polycondensed by acid treatment in 1 N HCl to form an electrochromic PAA/WO 3 film. Transmission electron microscopy showed that the PAA/WO 3 film contains regularly dispersed WO 3 grains with an average size of ∼5 nm. According to the Auger depth profile analysis, the relative content of W, O, and C was quite homogeneous along the height of film. Depending on the concentration of PAA coating solution (1.0-3.0 wt %), the thickness and tungsten oxide content of the film were found to vary; therefore, the electrode property of the PAA/WO 3 layer could easily be controlled. By using a 2.5 wt % PAA solution, an optimum electrochromic function was achieved with a coloration efficiency of ∼38 cm 2 /C and a cycle life of >11 000 under operation with Q ) 12.5 mC/cm 2 .

Microstructural and electrochromic properties of tungsten oxide thin films produced by surfactant mediated electrodeposition

“…For mesoporous WO 3 films synthesized from a WCl 6 -ethanol sol containing P 123 and calcined at 400 8C, coloration efficiency varied from 21 to 23.5 cm 2 C À1 [10]. A coloring efficiency of 40 cm 2 C À1 (l = 550 nm) was observed by Choy et al [36] for a poly(acrylic acid)/WO 3 hybrid film under a fixed lithium intercalation level of 12.5 mC cm À2 . Ashrit [37] obtained an integrated transmission modulation of 45% over the visible region for vacuum evaporated WO 3 films lithiated with 12.5 mC cm À2 of charge.…”

A WO3–poly(butyl viologen) layer-by-layer film/ruthenium purple film based electrochromic device switching by 1 volt application

“…The poly(peroxotungstate) species therein is converted to tungsten oxide by decomposition of the peroxo groups by heating the poly(peroxotungstate)-PBV LbL film at 60 1C for 4 h. The heat treatment, and the conversion of poly (peroxotungstate) to WO 3 is responsible for the rough topography of the WO 3 -PBV film. In another study, WO 3 films were fabricated using poly(acrylic acid) (PAA) and ammonium tungstate solutions through alterative dip coating method [19], where the ammonium tungstate component was polycondensed by an acid treatment in 1 N HCl to form an electrochromic PAA/WO 3 film. Authors [19] observed that the film had a high thickness of about $ 1.2 μm, which is comparable to the maximum thickness achieved for the WO 3 -PBV LbL film.…”

“…In another study, WO 3 films were fabricated using poly(acrylic acid) (PAA) and ammonium tungstate solutions through alterative dip coating method [19], where the ammonium tungstate component was polycondensed by an acid treatment in 1 N HCl to form an electrochromic PAA/WO 3 film. Authors [19] observed that the film had a high thickness of about $ 1.2 μm, which is comparable to the maximum thickness achieved for the WO 3 -PBV LbL film.…”

“…Poly(aniline)-WO 3 hybrid thin films were synthesized via a molecular assembling route in a solution of aniline using peroxotungstic acid (PTA) as the dopant [18]. In yet another study, WO 3 films were fabricated using poly (acrylic acid) (PAA) and ammonium tungstate solutions through alterative dip coating method [19]. Previously, a LbL assembly of poly(butyl viologen)-poly(styrene sulfonate) was fabricated as a Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/solmat solid thin film; however, the electrochromism of the film was not studied by the authors [20].…”

Synthesis, characterization of magnesium-substituted tungstoarsenate, , and its electrochromism

“…It is well known that the monolayer and multilayer films containing POMs have represented the electrocatalytic properties towards the reduction of substrates such as NO À 2 , NO, BrO À 3 , IO À 3 , H 2 and H 2 O 2 [33][34][35] and the oxidation of substrates such as As 2 O 3 and C 2 O 2À 4 . as well as the electro-and photo-chromic properties [36][37][38][39][40]. Meantime, the potential application as pH-sensitive probe was also reported [41].…”