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

Abstract

Nanoporous structures have proven as an effective way for enhanced electrochromic performance by providing a large surface area can get fast ion/electron transfer path, leading to larger optical modulation and fast response time. Herein, for the first time, application of vacuum cathodic arc plasma (cAp) deposition technology to the synthesis of Wo 3 /NiO electrode films on ITO glass for use in fabricating complementary electrochromic devices (ECDs) with a ITO/WO 3 /Liclo 4-perchlorate solution/ NiO/ITO structure. Our objective was to optimize electrochromic performance through the creation of electrodes with a nanoporous structure. We also examined the influence of WO 3 film thickness on the electrochemical and optical characteristics in terms of surface charge capacity and diffusion coefficients. The resulting 200-nm-thick WO 3 films achieved ion diffusion coefficients of (7.35 × 10 −10 (oxidation) and 4.92 × 10 −10 cm 2 /s (reduction)). the complementary charge capacity ratio of Wo 3 (200 nm thickness)/ NiO (60 nm thickness) has impressive reversibility of 98%. A demonstration ECD device (3 × 4 cm 2) achieved optical modulation (ΔT) of 46% and switching times of 3.1 sec (coloration) and 4.6 sec (bleaching) at a wavelength of 633 nm. In terms of durability, the proposed ECD achieved ΔT of 43% after 2500 cycles; i.e., 93% of the initial device.

High-Performance Complementary Electrochromic Device Based on Iridium Oxide as a Counter Electrode

“…Note that the modulation of the optical transmittance of the 100-nm-thick IrO 2 film with an Ar/O 2 ratio of 1/3 was higher than that of the other samples, as indicated by the larger enveloped area in the CV curve in Figure 2 and Figure 7 show that the coloration and bleaching state of ECDs, as analyzed during a continuous potential from −2 V (coloration potential, Vc) to 2 V (bleaching potential, Vb), were measured by the CA curves and the in-situ optical response of transmittance at 633 nm. The coloration and bleaching of the switching times and speed were very important factors for the ECD system; it is defined as the time required for a 90% change in the full transmittance modulation [ 8 ]. Figure 8 presents the electrochromic performance of optical transmittance modulation at 633 nm after 1000 cycles.…”

“…Recently, researchers have investigated more study in monolithic coatings than higher-performing multilayers. The formation of electrode structure is controlled by the flow of argon (for insertion) and oxygen (reaction) [ 8 ]. In the recent years, P. W. Chen et al [ 32 ] investigated in vacuum cathodic arc plasma (CAP) to fabricate all solid-state electrochromic devices (ECDs) with tantalum oxide (Ta 2 O 5 ) as ion conductor layer.…”

“…We have manufactured ECD composing of a WO 3 electrode film on IZTO/ITO/glass and a counter-electrode (Pt mesh) using 0.2 M LiClO 4 /PC solution. P. W. Chen et al [ 8 ] used CAP deposition to make the porous surface structure of WO 3 /NiO films to upgrade the electrochromic performance. They found that the thickness of WO 3 layers is an essential factor of ECDs for optical and electrochemical properties.…”

“…Furthermore, ECDs can save renewable energy and cause a persistent reversible color change upon the application of a small voltage [3,4] to reduce the energy consumption significantly; therefore, they are an extraordinary material providing some unique advantages such as larger optical modulation and better cyclic stability against sunlight exposure, for smart windows in a green building environment [5,6]. In general, ECD consists of a five-layer structure such as TCO/EC/IC/CE/TCO layers, where TCO, IC, and CE are transparent conducting oxide, ion conducting layer, and counter electrode, respectively [7][8][9]. In recent years, electrochromic materials have attracted considerable research interest in numerous metal-oxides, including molybdenum trioxide (MoO 3 ), vanadium oxide (V 2 O 5 ), niobium oxide (Nb 2 O 5 ), and titanium dioxide (TiO 2 ) [9,10].…”

Influence of Co concentration on properties of NiO film by sparking under uniform magnetic field

“…Nickel oxide (NiO) is essentially transition metal oxides, which has been intensively studied due to its high transparency and wide band gap 1 , 2 . Therefore, the NiO is applied in various applications such as a gas sensor 2 , hole transport layer 3 , capacitor 4 , electrochromic 5 and photodetector 6 . Additionally, the NiO has also found widespread applications in a heterojunction as well 7 , 8 .…”