Abstract
In complementary electrochromic devices (ECDs), nickel oxide (NiO) is generally used as a counter electrode material for enhancing the coloration efficiency. However, an NiO film as a counter electrode in ECDs is susceptible to degradation upon prolonged electrochemical cycling, which leads to an insufficient device lifetime. In this study, a type of counter electrode iridium oxide (IrO2) layer was fabricated using vacuum cathodic arc plasma (CAP). We focused on the comparison of IrO2 and NiO deposited on a 5 × 5 cm2 indium tin oxide (ITO) glass substrate with various Ar/O2 gas-flow ratios (1/2, 1/2.5, and 1/3) in series. The optical performance of IrO2-ECD (glass/ITO/WO3/liquid electrolyte/IrO2/ITO/glass) was determined by optical transmittance modulation; ∆T = 50% (from Tbleaching (75%) to Tcoloring (25%)) at 633 nm was higher than that of NiO-ECD (ITO/NiO/liquid electrolyte/WO3/ITO) (∆T = 32%). Apart from this, the ECD device demonstrated a fast coloring time of 4.8 s, a bleaching time of 1.5 s, and good cycling durability, which remained at 50% transmittance modulation even after 1000 cycles. The fast time was associated with the IrO2 electrode and provided higher diffusion coefficients and a filamentary shape as an interface that facilitated the transfer of the Li ions into/out of the interface electrodes and the electrolyte. In our result of IrO2-ECD analyses, the higher optical transmittance modulation was useful for promoting electrochromic application to a cycle durability test as an alternative to NiO-ECD.
Highlights
Electrochromic devices (ECDs) have attracted considerable attention because they have tremendously promising applications in energy-saving smart windows that can enhance the optical properties and durability reversibly upon the application of a Direct Current (DC) voltage [1,2]
We presented a comparison of electrodes on IrO2/indium tin oxide (ITO) and nickel oxide (NiO)/ITO films with various Ar/O2 gas-flow ratios in electrochromic devices (ECDs) and investigated the electrochemical, structural, and optical properties
We developed electrochromic electrodes by using the cathodic arc plasma (CAP) technique as an alternative method to fabricate ECDs with a high deposition rate and at a low cost
Summary
Electrochromic devices (ECDs) have attracted considerable attention because they have tremendously promising applications in energy-saving smart windows that can enhance the optical properties and durability reversibly upon the application of a Direct Current (DC) voltage [1,2]. 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; 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 addition to the oxides, conducting polymers are widely studied in electrochromic devices [11,12]
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have