Synthesis and characterization of rough electrochromic phosphotungstic acid films obtained by spray-gel process

Abstract

Rough electrochromic phosphotungstic acid (PWA) films were fabricated by spraying a gel of phosphotungstate anions with a molar ratio of P:W = 1:12 onto glass substrates precoated with transparent and electrically conducting SnO 2 :F at 300 °C. The analysis by X-ray photoelectron spectroscopy (XPS) determined that the P:W molar ratio in the films was approximately 1:14. Infrared spectroscopy (IR) and X-ray diffraction (XRD) showed that the film is a polycrystalline phosphotungstic acid. SEM micrographs showed that the films present a rough morphology based on fiber-shape bridges. Optoelectrochemical measurements demonstrated pronounced electrochromism in the PWA films upon H + intercalation/deintercalation with a high diffuse reflectance (R d) and transmittance (T d). We found for as-deposited films that R d /total reflectance (R t) and T d /total transmittance (T t) at 550 nm was around 0.83 and 0.68, respectively. This ratio decreases at bleached state to 0.74 and 0.41 for R d /R t and T d /T t , respectively.

Flexible, Switchable Electrochromic Textiles

“…[2] Figure 2. (a) WO 3 as example for cathodic electrochromism, [18][19][20][21][22][23][24][25] (b) PANI as an example for anodic electrochromism. [8][9][10][11][12][13] tungsten-containing solution.…”

Effect of Tl+ Intercalation on Electrochromic Behavior of Tungsten Heteropolyoxometalate Polymeric Thin Films

“…From the slope of the curve of the cathodic/anodic peak current versus square root of scan rates in the linear part, the diffusion coefficients were calculated. For PTA it is found to be 9.49 × 10 −11 cm 2 /sec and 6.96 × 10 −11 cm 2 /sec for intercalation and deintercalation process, respectively and for TlPTA it is found to be 4.8 × 10 −10 cm 2 /sec and 6.09 × 10 −11 cm 2 /sec for intercalation and deintercalation process, respectively …”

“…For PTA it is found to be 9.49 Â 10 À11 cm 2 /sec and 6.96 Â 10 À11 cm 2 /sec for intercalation and deintercalation process, respectively and for TlPTA it is found to be 4.8 Â 10 À10 cm 2 /sec and 6.09 Â 10 À11 cm 2 /sec for intercalation and deintercalation process, respectively. [12,13] Cyclic Voltammetry (CV) for Testing of Durability of Phophotungstic Acid (PTA) and Tl þ Intercalated Phophotungstic Acid Thin Films Figure 2a and b shows CV spectra recorded for phophotungstic acid (PTA) and Tl þ intercalated phosphotungstic acid (Tl 3 PO 4 ) (WO 3 ) 12 thin films for its 100 th , 200 th , 500 th and 1000 th cycle. From the figures, it was observed that with an increase in number of cycle threshold voltage (Et), the voltage corresponding to rapid surge of Li þ ions in to the phosphotungstic acid (PTA) and Tl þ intercalated phosphotungstic acid Tl 3 (PO 4 ) (WO 3 ) 12 film shifts anodically.…”

“…A typical CA trace obtained during coloration and bleaching of as deposited phosphotungstic acid (PTA) and Tl þ intercalated phosphotungstic acid (Tl 3 PO 4 ) (WO 3 ) 12 thin films is shown in Figure 3a and b. During the experiment, the voltage was stepped from its rest potential of 0.0 V to À0.5 V for 10 s (coloration) and then reversed to þ0.5 V for next 10 s (bleaching).…”

Electrochromic materials and devices: Brief survey and new data on optical absorption in tungsten oxide and nickel oxide films

“…Such work has been reported for oxides based on tungsten, iridium, vanadium, and nickel. W oxide colours under charge insertion and is referred to as a cathodic electrochromic materials, whereas oxides of Ir and Ni colour under charge & W oxide films have been prepared by evaporation [28 -31], sputtering [32,33], spray pyrolysis [34], sol -gel deposition [35 -40], and electrodeposition [41,42]; work has been reported also on W oxide containing Mo (made by chemical vapour deposition [43] and electrodeposition [44]), V (made by sputtering [45]), Ta (made by pulsed laser ablation [46]), Ti (made by electrodeposition [47] and spin coating followed by a templating technique [48]), and P (made by sol -gel deposition [49]); & Ir oxide films have been prepared by electrodeposition [50,51]; work has been reported also on Ir oxide containing and Ta (made by sputtering [52]); & V oxide films have been prepared by sputtering [53]; work has been reported also on such films with polymer additives [54]; and & Ni oxide films have been prepared by reactive evaporation [55], pulsed laser deposition [56], sol -gel deposition [57,58], and electrodeposition [59]; work has been reported also on such sputter-deposited films containing Mg, Al, Si, V, Zr, Nb, Ag, Ta [60] as well as Au [61].…”