Multiwavelength Color Switching from Polyaniline‐Viologen Bilayer: Inching toward Versatile All‐Organic Flexible Electrochromic Device

Abstract

solely by the presence of various electronic equipment's and gadgets. [1][2][3][4] However, as everything comes at the expense of something, the world right now is clearly heading toward some serious shortage of very essential commodities. In order to resonate with the current demand of the society, the major issue at hand that needs to be addressed is the energy crisis we are facing right now. Although, a lot of work is currently going in the industrial front, a good understanding about materials and composites is required for not only making energy storage/conversion, but also energy saving. [5][6][7][8][9] Electrochromic Device (ECD) is one such apparatus that can potentially reduce the energy requirement in buildings, air crafts, automobiles etc., in form of temperature regulators. [10] The basic mechanism of ECDs that includes visible optical changes occurring due to application of some amount of bias is basically driven by redox reactions happening at individual electrodes. [11][12][13] Compatible materials are then chosen and used in a sandwiched manner along with a suitable electrolyte to obtain a final ready-to-use device. [14][15][16] Ever since the birth of Electrochromism by Deb [17,18] a lot of progress in terms of basic parameters like switching speeds, contrast ratio, coloration efficiency etc., has been achieved. Transition Metal Oxides (TMOs like WO 3 ), [19] various polymers (Polythiophene etc) [20,21] metal complexes (like Prussian blue, etc.), [22] and metallo-supramolecular polymers [23] are the materials that act as active layer in an ECD. It is important to mention that when these materials are used in isolation, the devices have little practical application. As a consequence, a device needs to be designed appropriately for optimized operation. Choosing more than one layer has helped in not only improving the device performance, but also in getting multiple color switching. This design, like all others, come with certain constraints that limits the versatility of a device leaving a room for improvement in terms of enhancement of para meters. [10,[24][25][26] Newer ways need to be explored so that a versatile device that can operate with low power consumption, multiple wavelengths and comes with a possibility of integrated in the form of flexible device, can be fabricated.Fundamental applications of ECD such as usage in smart windows of buildings, aircrafts etc., require them to switch Search for a versatile flexible all-organic liquid electrolyte-less solid-state electrochromic device continues. In this quest, a polyaniline-Viologen-(PANI-EV)-based electrochromic device has been reported and designed based on the complementary redox behavior and easy processibility. Electrochromic electrodes are first individually characterized before the device fabrication, to check their compatibility. The polyaniline electrode is electrodeposited and characterized using scanning electron microscopy and Raman techniques followed by bias dependent absorbance measurements to understand its color switching c...

Electrochromic Strategies for Modulation between Primary Colors: Covering the Visible Spectrum

“…One of the most important parameters that provides a wholesome information about the devices’ performances is its efficiency (η), and the same is defined using eq : ,, η = normalΔ O D Q where ΔOD is the change in optical density/optical contrast, i.e., the difference between the maximum and minimum absorbance value, and Q is the amount of charge intercalated/deintercalated by the device to induce the above change in optical density. The η is thus expressed in units of cm 2 /C.…”

“…With the advent of electricity came unimaginable capabilities leading to development of electronic and optoelectronic devices and gadgets which are integral parts of the current technological backbone. Tuned with the latest technology, devices such as solar cells, batteries, and supercapacitors have become quite integrated in human life to provide comfort and ease. , Among many, electrochromic devices (ECDs) exhibit unique reversible optical modulations on application of bias. , Electrochromism, the phenomenon of such a bias-induced color switching behavior, first made its appearance around 1973 and has continued to impress researchers ever since . In addition to simple color switching, ECDs are known for their multipurpose applications as rear-view mirrors, smart windowpanes in automobiles, electronic signboards, advanced eye gears, sweat sensors, etc. , There have been plenty of materials that display such color change and are the potential candidates for ECDs.…”

Mescoporous Nickel Titanate–Titanium Oxide Complex Material for Enhanced Energy Storage Application

“…38 and conducting polymers. 27,39,40 They have high energy density, high specific capacitance, and fast and reversible Faradaic reactions but low power density. [33][34][35][36]38 However, TMOs have low electrical conductivity and high rigidity resulting in low power density and little flexibility.…”

Multicolor Bipolar Modulation of Titanium–Chromium Oxide Electrochromic Coatings

“…4 Transition metal oxides have been widely studied for their electrochromic properties owing to their versatile compositions and crystal structures. For example, WO 3 and V 2 O 5 are cathodic electrochromic materials, whose layers change colors under reductive electrochemical potentials, 5 while NiO x , IrO x , and CrO x are used as anodic electrode materials. 2,6,7 In electrochromic devices (ECDs), electrochromic materials are treated as the working electrodes that are often encapsulated with ion-conducting electrolytes, transparent conductive electrodes, and glass or polymeric protective layers.…”

“…Transition metal oxides have been widely studied for their electrochromic properties owing to their versatile compositions and crystal structures. For example, WO 3 and V 2 O 5 are cathodic electrochromic materials, whose layers change colors under reductive electrochemical potentials, while NiO x , IrO x , and CrO x are used as anodic electrode materials. ,, In electrochromic devices (ECDs), electrochromic materials are treated as the working electrodes that are often encapsulated with ion-conducting electrolytes, transparent conductive electrodes, and glass or polymeric protective layers. ,, Otherwise, these color-changing materials degrade or corrode under wide-ranging pH and salinity. Therefore, the development of EC materials that can serve with high stability, balanced EC performance, and wide color modulation capability in various moist, dry, and saline environments, in contact with aqueous or nonaqueous liquids, is greatly desired. , …”