An Inverted Sandwich Electrochromic Device Architecture Does Not Require Optically Transparent Electrodes

Abstract

All currently known sandwich‐type electrochromic devices (ECDs) require at least one optically transparent electrode (OTE) for their operation. Here, it is demonstrated that this requirement is conceptually redundant. The so‐called inverted sandwich ECD architecture is introduced, with its principal components being: two solid optically nontransparent electrodes (high electrical conductivity material), an insulator that prevents a short‐circuit between the electrodes, and an electrochromic mixture applied on a solid carrier. The modus operandi of the present proof‐of‐concept solution‐phase double‐sided ECD is a reversible color change of the indicator dye caused by the variations in pH of the water‐based electrolyte solution due to electrolysis. Application of the inverted sandwich topology to make electrochromic tapes is given.

Multicolor Transparent‐Conductive‐Electrode Free Electronic Paper based on Steel Foil and Water Electrolyte with pH Indicator Dyes

“…Since 2.5 m sodium acetate was used in the constructed device, the pixel dyed with methyl red performed less well because the pH required for color change of methyl red is about 4.6, while the pH of the sodium acetate solution is relatively high (8–9). [ 13 ] In addition to the UV‐vis spectra of the 4 pixel device, additional spectrum was recorded for a single‐pixel device using the dye phenol red. This dye has a color transition at pH between 6.2 and 8.2 and changes its color from yellow in acidic to red in basic environments and is therefore much more suitable for use with sodium acetate.…”

Electrochromic Device Demonstrator from Household Materials

“…Even though ECDs can be relatively simple to assemble, several issues arise when using them as EC demonstration devices in scholarly applications. Didactic examples of ECDs employ expensive OTE materials, preparation of metal oxides at elevated temperatures, or use of hazardous metals such as lead or nickel and/or lithium salts. − However, several types of simple solution-phase ECDs are known, which use pH indicators as an electrochromic dye. , Their EC mixture consists of a pH indicator dye dissolved in, for example, aqueous solution of supporting electrolyte to increase its ionic conductivity, and the change in the pH near the electrodes due to water electrolysis causes the color change of the solution. These devices are suitable for educational purposes: they demonstrate the basic chemical principles (electrolysis, pH or redox indicators) as well as electrochromic aspects of materials (change in color) and develop practical skills of assembling simple functional ECDs.…”

“…Recently, we proposed a way to build an ECD without the need for OTE . We reuse its architecture here to provide a quick and simple way to assemble an ECD and test its function in chemical education.…”

Partly Covered PProDOT‐Me2 on MoS2 Nanosheets Counter Electrode for High‐Performance Self‐Powered Electrochromic Device

“…Electrochromic devices (ECDs), which can be reversibly color changed by the applied external voltage, have been attracted remarkable attention for energy‐harvesting smart windows applications. [ 1–3 ] However, it requires an additional circuit as a power supply to operate under an applied voltage. Thus, integrating an internal potential for achieving a self‐powered electrochromic device (SP‐ECD) has been implemented.…”

“…Electrochromic devices (ECDs), which can be reversibly color changed by the applied external voltage, have been attracted remarkable attention for energy-harvesting smart windows applications. [1][2][3] However, it requires an additional circuit as a power supply to operate under an applied voltage. Thus, integrating Also, transparent conductive polymers, including polypyrrole (PPy), [20] polyaniline (PANI), [21] poly(3,4propylenedioxythiophe nes) (PProDOT), [22] and poly (3,4-(2,2dimethylpropylenedioxy) thiophene) (PProDOT-Me 2 ), [11] have been investigated as CEs due to high conductivity, good transparency, high electrocatalytic activity, high stability and appropriate for low-cost largescale production.…”