Solution-Processed Interfacial PEDOT:PSS Assembly into Porous Tungsten Molybdenum Oxide Nanocomposite Films for Electrochromic Applications

Abstract

Electrochromic devices (ECDs) have received increased attention for applications including optoelectronics, smart windows, and low-emission displays. However, it has been recognized that the ECDs with transition-metal oxide (TMO) electrodes possess a high charge transport barrier because of their poor electrical conductivity, which limits their electrochromic performance. In this work, we addressed this limitation by utilizing a conjugated polymer to fabricate an organic-inorganic nanocomposite film that decreases the charge transport barrier of typical TMO electrodes. Using a conventional spray-layer-by-layer (spray-LbL) deposition technique, we demonstrate an electrochromic film composed of porous layers of tungsten molybdenum oxide (WMoO) nanorods permeated with an interconnected conductive layer of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The introduction of PEDOT:PSS is shown to significantly reduce the charge transport barrier, allowing the nanocomposite WMoO/PEDOT:PSS electrode to exhibit significantly improved electrochromic switching kinetics compared with the deposited WMoO films. Furthermore, the optical contrast of the nanocomposite electrode was observed to be superior to both pure PEDOT:PSS and WMoO electrodes, with a performance that exceeded the linearly predicted contrast of combining the pure films by 23%. The enhanced performance of the PEDOT:PSS-intercalated porous WMoO nanocomposite electrodes and the facile synthesis through a spray-LbL method demonstrate a viable strategy for preparing fast assembling high-performance nanocomposite electrodes for a wide variety of electrochemical devices.

Rechargeable Aqueous Hybrid Zn2+/Al3+ Electrochromic Batteries

“…The WO 3 cathode exhibits DT of $88% at 632.8 nm (without background correction), which is higher than that measured in 1 M ZnSO 4 ($82%, Figure S10) and higher than previous reports. 2,14,20,[24][25][26] Notably, the WO 3 cathode in hybrid Zn 2+ / Al 3+ -based electrolyte exhibits strong light absorption in the green and red regions of the visible spectrum ($86% at 550 nm), compared to the WO 3 cathode in 1 M ZnSO 4 ($72.9% at 550 nm, Figure S10). This is due to the reduction of W 6+ to W 4+ in the hybrid system.…”

Transparent inorganic multicolour displays enabled by zinc-based electrochromic devices

“…4d ). The self-colouration time (spontaneous colour switching time), defined as the time required to achieve 90% of the maximum optical contrast 29 , was measured to be 7.8 s. Furthermore, the dynamic transmittance characteristics of the SVO electrode were tested within the applied voltage window between 0.2 and 2.0 V. As shown in Fig. 4e , the response times are calculated to be 12.6 s for colouration (green) and 25.4 s for bleaching (orange).…”

Fast response of complementary electrochromic device based on WO3/NiO electrodes

“…A pair of transparent conducting layers sandwich an ionic conduction layer (electrolyte) in contact with an electrochromic (EC) layer and an ion storage (complementary) layer [14][15][16] . Tungsten oxide (WO 3 ) is known as one of the most popular cathodic coloration material and nickel oxide (NiO) as typical anodic coloration material, which has been intensively investigated [14][15][16][17] . WO 3 film is a transition metal oxide, which can be reversibly switched between colorless and blue under positive or negative voltage, respectively 18,19 .…”