Solid-state Electrochromic Devices Research Articles

Ionic conductivity and dielectric characteristics of a Li incorporated PVA electrolyte membrane and a study of a fully solid-state electrochromic device based on it

The construction and study of a fully solid state electrochromic (EC) device with cathodic coloration exhibiting very fast response times (< 1s) is reported using a WO3 EC layer and a poly (vinyl alcohol) (PVA)- Lithium acetate membrane electrolyte. Broadband dielectric studies on the polymer membranes with different Li concentrations show multiple relaxation mechanisms out of which a segmental relaxation prominent beyond a certain composition is strongly correlated with Li-ion conduction yielding better ionic conductivity and reversible coloration in the EC device. The relatively high Li conductivity in PVA has a direct correspondence with the lowering of the crystallinity of PVA and a decrease of the glass transition temperature, Tg with increasing Li addition. A simple model of the coloration process suggests that the short electrolyte diffusion length coupled with a high electric field and an interfacial emf that varies as ≈t−0.6 results in the swift current response of the film with an optimal performance at 20 wt.% Li in PVA, exceeding which irreversible coloration can occur on the surface. The transient current is crucial for the observed swift switching characteristics. Ageing studies for almost a month indicate potential stability of the EC device for over 150 cycles.

Combining Bragg reflector and Fabry–Pérot cavity into a solid-state electrochromic device for dynamic modulation

Combining Bragg reflector and Fabry–Pérot cavity into a solid-state electrochromic device for dynamic modulation

Utilizing rare earth titanates to improve performance of solid-state electrochromic device

Exploring new materials and synthesis recipes are required to enhance the electrochromic performance especially, when used in solid-state devices. Here, polycrystalline gadolinium titanate (Gd2TiO5 or GTO), synthesized using a simple solid-state reaction method, has been used for this purpose by combining it with polythiophene (P3HT). The electrochemical investigation of the Gd2TiO5 doped P3HT electrode has been carried out using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which reveals the dominance of diffusion-controlled mechanism over charge storage on the electrode surface as compared to the P3HT electrode. The Gd2TiO5 doped P3HT solid-state electrochromic device shows color modulation at 515 nm and 670 nm wavelengths with a color contrast of as high as 79% and 42%, respectively, under an external bias of as low as ±1.4 V. The prepared device switches between maroon to a transparent state in less than a second under the external bias (±1.4 V) with a high coloration efficiency of 346 cm2/C. The device shows improved cycle life over 100 switching cycles at both the wavelengths, which makes it more suitable for real-life applications.

Effect of hBN on Response Times of PEO-Based Electrochromic Devices

In this study, all solid state electrochromic devices (ECDs) without plasticizer such as propylene carbonate were fabricated by sol-gel spin coating method. WO3 nanoparticles and PEO based polymer electrolyte solutions with hBN and without hBN nanoparticles were prepared. These solutions were sol-gel spin- and dip-coated on ITO-glass, respectively. For determining the effect of hBN nanoparticles, four configuration of ECDs were fabricated. The fast bleaching and coloring times of fabricated ECDs were obtained with hBN nanoparticles in WO3 and PEO based polymer electrolyte thin films as 1.15 seconds. Glass/ITO/hBN-WO3/hBN-PEO-based-polymer electrolyte/ITO/Glass electrochromic device is turned on and off 60 times. After 60 cycle, the device coloring time changed to 2-3 seconds, bleaching times changed to 30 seconds.

Electro-optical performance of solid-state electrochromic device based on self-supporting electrolyte

In this study, an innovative self-supporting electrolyte has been prepared and applied to electrochromic device with a structure of ITO/WO3/SSE/NiO/ITO. Since the self-supporting electrolyte exhibits excellent transparency and high ionic conductivity, enabling the electrochromic device to demonstrate superior electro-optical performance including: a significant optical transmittance modulation (41.2 % at 550 nm), good cycling stability (retaining 95 % optical transmittance modulation at 550 nm after 1000 cycles), and high coloration efficiency (87 cm2 C⁻1 at 550 nm). Taking into account the easy preparation characteristics of this electrolyte and its suitability for large-scale device preparation, it can be considered as a potential candidate for electrolytes applied in high-performance electrochromic devices in the future.

Ferrocene-Functionalized Fulleropyrrolidine Derivative: A Performance Enhancer for Solid-State Electrochromic Devices

Ferrocene-Functionalized Fulleropyrrolidine Derivative: A Performance Enhancer for Solid-State Electrochromic Devices

Nonconventional Symmetric Double-Side Electrochromic Devices Employing a Nafion Conductive Layer to Unlock Superior Durability.

In this work, we present a methodology to create an effective novel double-sided symmetric architecture of solid-state electrochromic devices. This principally new nonconventional configuration provides access to novel electrochromic systems that could be applicable for the creation of smart double-side signage, smart boards, nonemissive displays, and other smart interactive devices that change their color upon application of a voltage. The proposed configuration is based on the assembly of two identical electrochromic materials facing each other through an opaque optical separator. As a proof of concept, we use an electrochromic material based on bis(4'-(pyridin-4-yl)-2,2':6',2″-terpyridine) iron complex, covalently immobilized on screen-printed surface-extended ITO support. The symmetric configuration allows for a drastic enhancement of the overall stability of the device due to both attenuation of the counter electrode polarization and minimization of electrolyte decomposition. A nontransparent ion-permeable separator, in turn, allows observing the color change of only one of the electrodes by cutting off the optical contribution of the electrode located behind it. Further functionalization of the electrochromic material with a thin layer of Nafion is a beneficial strategy to significantly boost up long-term durability of the devices. Applying a layer of Nafion to the electrochromic material results in an increase in ionic conductivity within the device and ensures better retention of electrochromic molecules on the surface, thus minimizing device decomposition during long-term electrochemical cycling. An electrochromic device that bears Nafion-functionalized electrodes can operate (i) in the dual-side mode, where both sides demonstrate effective electrochromic performance; or (ii) in a one-side manner, where only one side of the device changes color. Notably, when operating in the one-side mode, the device withstands 70,000 cycles, after which the performance of the device can be resumed by simply turning the device to the other side (via switching the polarity of the electrodes).

Convenient-assembled, open-ended solid-state electrochromic devices enabled by electrolyte glue

Electrochromic (EC) technology has a tremendous development over the past few decades and attracts wide attention due to its promising applications in smart windows, smart displays and wearable electronics. However, strict sealed requirements of EC devices increase the difficulty of manufacturing processing and production cost, limiting their practical application in common life. Moreover, the disassembly and replacement of EC devices are still enormous challenges in practical application. Here, open-ended solid-state EC devices were prepared by directly sticking the EC electrode and counter electrode with photocurable electrolyte glue which did not require additional encapsulation and could be conveniently assembled and replaced by ourselves in common life. The poly(butyl acrylate-co-methoxypolyethylene glycol acrylate) (P(BA-co-mPEGDA))-based solid-state electrolyte formed after UV curing of electrolyte glue exhibited excellent adhesion to electrodes through the construction of intimate contact interface, which improved the ion transport efficiency at the interface and interface stability of EC devices. The Open-ended solid-state EC devices exhibited excellent electrochemical, environmental and mechanical stability, and show promising applications in exchangeable smart windows and designable wearable displays.

Exploring a Redox-Active Ionic Porous Organic Polymer in Environmental Remediation and Electrochromic Application.

Here, we report the design and synthesis of a redox-active multifunctional ionic porous organic polymer iPOP-Bpy with exchangeable Br- ions, incorporating viologen as a redox-active building block. The material shows not only excellent iodine uptake capacity in the vapor phase (540 wt %) but also in the organic (1009.77 mg g-1) and aqueous phases (3921.47 mg g-1) with very fast adsorption kinetics in all cases. The material also shows its utility in being used as a solid-state NH3 vapor sensor as it shows very fast color switching in the presence of NH3 vapor. Furthermore, the material found application as a p-type complementary electrochromic electrode and was fabricated into a bilayer device. Excellent coloration efficiency, high switching speed, and good color contrast were obtained as investigated using bias-dependent optical and spectroelectrochemical studies, paving the way for fabricating power-efficient solid-state electrochromic devices.

Polyacrylamide gel electrolyte for high-performance quasi-solid-state electrochromic devices

Electrolytes, especially the gel polymer electrolytes (GPEs) play an important role in an electrochromic device (ECD), and have received extensive attention in recent years. GPEs combine the advantages of both liquid and solid electrolytes, and provide a new solution for realizing solid-state ECDs. In this work, polyacrylamide (PAM) GPE with a high ionic conductivity of 6.4 × 10−2 S cm−1 at room temperature was synthesized by an in situ free radical polymerization in an ECD, where Prussian blue (PB) and tungsten trioxide (WO3) were used as electrochromic (EC) layers. The in situ polymerization realizes a much better match between the electrolyte layer and the EC film. A large optical modulation of 74.8% at 678 nm and a high coloration efficiency of 154.5 cm2·C−1 are achieved for the obtained PB/PAM GPE/WO3 device. Due to the high ionic conductivity and fast ion transport, the ECD also has a fast coloration time (tc) of 2.1 s and a bleaching time (tb) of 1.7 s. Additionally, the ECD maintains 90.6% of optical modulation after 13,500 cycles, demonstrating an excellent cycling stability.

Dual Redox-Responsive Os/Ru-Based Alternated Heterobimetallic Supramolecular Polymer as a Multicolor Electrochromic Material for Camouflage Devices

Materials that show multicolor electrochromism, including yellow and green, are highly applicable for various smart applications including voltage-tunable multicolor electrochromic (EC) displays and camouflage devices. Although metallo-supramolecular polymers (MSPs) show excellent EC color variability with attractive EC properties, the generation of multicolor electrochromism from one MSP is still difficult. Moreover, an MSP-based multicolor EC device (ECD) that also exhibits yellow and green EC colors has not been realized to date. Herein, we report the synthesis of a dual redox-responsive heterobimetallic supramolecular polymer (PolyOsRu) as a multicolor EC material that can also be used for camouflage applications. PolyOsRu was synthesized by stepwise homoleptic complexation of Os2+ and Ru2+ ions using a 2,2′:6′,2″-terpyridine-based ligand and characterized by various analytical and spectroscopic techniques. The polymer shows broad absorption (312–671 nm) and well-separated dual redox potentials of Os2+/Os3+ (E1/2 = 0.59 V) and Ru2+/Ru3+ (E1/2 = 0.93 V) pairs. A thin film of PolyOsRu on ITO displays reversible multicolor (brown–red ↔ yellow ↔ green) electrochromism with a maximum optical contrast of ∼58%, fast EC color switching (<1 s), a good coloration efficiency of 404.39 cm2/C, and a more than 2400 EC cycling stability. Finally, the fabrication of a solid-state ECD and a prototype EC camouflage display with the polymer film is demonstrated to represent its potentiality as a multicolor EC material for display and camouflage applications.

All-polymer solid state electrochromic device for low voltage and fast modulation between primary colors

The fabrication of promising devices requires involvement from multiple dimensions. With the ability to display three primary colors from a single device, electrochromic devices become more valuable for smart displays. One such attempt has been reported here by demonstrating Red-Green-Blue color modulation from a solid state device fabricated by combining two different conducting polymers, polyaniline (PANI) and polythiophene (P3HT), where they mutually support each other. Electrochromic properties are demonstrated on both electrodes, which can be achieved by selecting an appropriate bias for displaying the three primary colors in a single system. In addition, the device delivers faster switching (500 ms) and better coloration efficiency up to 540 cm2/C, thanks to the complementary redox activity of the PANI and P3HT electrodes.

Functionalized methyl cellulose/LiClO4 composite as an environmentally friendly quasi-solid polymer electrolyte for solid-state electrochromic devices and cellulose-based supercapacitors

Electrochemical devices, including energy storages and modulators, are expected to play key roles in creating a sustainable future. However, to achieve the technological break-through in electrochemical technologies, the development of solid electrolytes applicable in various electrochemical devices seem necessary. In this study, an environmentally friendly fluorine-free quasi-solid polymer electrolyte derived from a functionalized cellulose composited with LiClO4 is synthesized. The synthesized quasi-solid polymer electrolyte, LiClO4–sulfonated methyl cellulose incorporating lithium ion (LiSMC), exhibits a high conductivity exceeding 1 mS/cm with negligible electron leakage. The LiClO4–LiSMC electrolyte also exhibits high optical transparency and mechanical flexibility, thus it can be applied in various solid-state electrochemical systems including electrochromic devices and energy storages. The applicability of the LiClO4-LiSMC electrolyte in quasi-solid-state electrochromic devices and cellulose-based supercapacitor is demonstrated, from which reduction of the operating voltage and enhancement in performances compared with the similar devices with conventional polymer electrolytes are demonstrated. The cellulose-based supercapacitor demonstrates an excellent stability against mechanical bending and charge–discharge cycling (up to 30,000 cycles) as well. Considering the natural abundance and low environmental impacts of cellulose and its derivatives, this work may open a path to the truly sustainable future through the development of an environmentally friendly material for environmentally friendly applications.

Growth, structural and vibrational properties of hydrogenated nanocrystalline silicon thin films prepared by radiofrequency magnetron sputtering technique at room temperature

The main objective of this paper is to produce the hydrogen-free and hydrogenated nanocrystalline silicon (nc-Si:H(x)) thin films deposited onto the single-crystalline Si(100) wafer by radio-frequency magnetron sputtering (RF-MS) at a substrate temperature of ∼ 300 K. Sputtering was effectuated by a microwave plasma in a mixture of argon and hydrogen (Ar + (H2(x)) gasses taken at different proportions of hydrogen dilution: x = 0, 2.5, and 5 sccm (standard cubic centimeter per minute). The deposition rates of the nc-Si:H were fully controlled, and the thickness of these films was ∼ 200 and 300 Å. Pt-capping layer was deposited in order to protect the nc-Si:H layer from oxidation. The thickness of the capping layer was fixed at ∼ 5 Å.The effects of the hydrogen flow rate and post-growth thermal treatment on the crystalline structure and morphology of as-grown nanocrystalline silicon thin films were systematically investigated by ultraviolet and x-ray photoelectron spectroscopy (UPS and XPS), atomic force microscopy (AFM), grazing incidence x-ray diffraction (GI-XRD) and micro-Raman spectroscopy methods. From the measured data, the average nanocrystallite sizes, surface morphology and other important characteristics of these thin films were analyzed. The grown nc-Si:H thin films may be used as a semiconducting electrode material for electrochemical proton production, which is of great technological importance, especially for solid-state electrochromic device applications.

Plasma assisted atomic layer deposition NiO nanofilms for improved hybrid solid state electrochromic device

Alternate methods for deposition of electrochromic metal oxide thin films need to be explored to obtain an optimized one while designing solid state hybrid or all-inorganic electrochromic device. To continue this quest, electrochromic performance from a hybrid electrochromic device obtaining using plasma assisted atomic layer deposition (ALD) grown nickel oxide (NiO) thin film and viologen has been studied. A few tens of nanometers thick films of NiO were deposited first on silicon to optimize the deposition parameters prior to depositing on Fluorine-doped Tin Oxide (FTO)/glass substrates for fabricating the device. The structural and morphological properties of as-prepared films were analyzed by scanning electron spectroscopy (SEM), x-ray diffraction (XRD), Raman spectroscopy and x-ray photo electron spectroscopy (XPS) techniques. Thereafter, a solid state organic-inorganic hybrid electrochromic device was fabricated using Nickel oxide (NiO) and ethyl viologen (EV). The device changes its color between transparent and blue states under the potential window of ±1.7 V while taking less than 2s for toggling between the two-colored states. The device also exhibits an impressive electrochromic behavior with coloration efficiency of 118cm2/C, contrast ratio of 21% and a good cycle life/stability. The ALD grown films appeared to have advantage over other methods as it yields an atomically smooth and crack-less nano film so that proper power utilization take place for color switching. All these results open a new way to the fabrication of inorganic component to fabricate high-performance hybrid solid state electrochromic devices.

2D-Layered Structure WS2 Nanosheets with Improved Electrochromism for Organic-Based Device

A solid-state electrochromic device is assembled via polythiophene (P3HT) and tungsten disulfide (WS2)-introduced ethyl viologen (EV) layers. The WS2 nanosheets are prepared via a facile one-step hydrothermal technique and investigated via scanning electron microscopy, X-ray diffractometer and Raman spectra. The device exhibits the enhanced electrochromic properties, such as response time (0.9 s/1.3 s), cyclic stability (1000 cycles), coloration efficiency (410 cm2 C−1), and the reversible color switching from pink to blue at the small applied potential (±1.6 V). This indicates that WS2 with graphene-like 2D-layered nanostructure has the weak van der Waals force between the layers, which can store and transfer electrical charges between the films and electrolytes, thus improving the carrier mobility, which is crucial for improving the properties of electrochromic device. In addition, the introduction of WS2 promoted the device to become one of the most efficient polythiophene-viologen based devices. Therefore, this work provides a basis for the development of new electrochromic devices as the alternatives to the graphene-based devices.

Bifunctional solid state electrochromic device using WO3/WS2 nanoflakes for charge storage and dual-band color modulation

An electrochromic supercapacitor device, designed using WO3/WS2 nanoflakes, successfully demonstrated excellent capacitive performance along with the ability of electrochromic color modulation when P3HT and viologen are used as electrochromic active components.

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

AbstractSearch 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 capabilities. In situ kinematics are performed on the finished solid–state device and electrochromic performance have been measured. An improved electrochromic performance can be observed as evident from &lt;1 s switching time while switching with a color contrast of ≈75% and good cycle life. The device displays switching in visible, as well as IR and NIR regions with an application of bias as low as 1.5 V. In addition to the multiple wavelength switching, a device has also been fabricated on a plastic electrode to demonstrate all‐organic flexible liquid electrolyte less solid–state versatile electrochromic device.

Ambipolar All-Organic Solid-State Electrochromic Device Using Electrodeposited Polyaniline: Improving Performance by Design

Ambipolar All-Organic Solid-State Electrochromic Device Using Electrodeposited Polyaniline: Improving Performance by Design

Zinc polyacrylamide hydrogel electrolyte for quasi-solid-state electrochromic devices with low-temperature tolerance

To achieve solid-state electrochromic devices, an acceptable compromise is to use polymer electrolyte gels, which combine the merits of liquid and solid electrolytes. However, many drawbacks remain, such as inflammability, a sharp decline in ionic conductivity at zero temperature, and interfacial problems with the electrodes. Here, we introduce a polyacrylamide (PAM)-based hydrogel electrolyte containing a high concentration of zinc ion, which delivers an ionic conductivity of 63.5 mS cm −1 at room temperature and 12.8 mS cm −1 at even −30°C. Based on the PAM-Zn 2+ electrolyte, we prepare a quasi-solid WO 3 /PAM-Zn/Zn energy storage electrochromic bifunctional device by in situ polymerization. The device exhibits excellent cycle performance (retaining 45.1% of optical contrast after 9,200 cycles) and a high areal capacity (278.3 mAh m −2 at 0.1 mA cm −2 ). Furthermore, larger-sized electrochromic devices also show ultra-long cycle stability and attractive anti-freeze properties. This work provides an idea for the large-scale fabrication of anti-freeze electrochromic devices with remarkable lifetimes. • An electrochromic bifunctional battery is designed and prepared • “Water-in-salt”-type electrolyte enables the device to work under −30°C • In situ hydrogel electrolytes polymerization improves the life cycle of the device In this paper, Ai et al. prepare a WO 3 -Zn electrochromic bifunctional battery by in situ polymerization based on a hydrogel electrolyte containing a high zinc concentration, which can work at −30°C and supply external power during the coloring process, widening the application range of electrochromic technic and zinc-ion batteries.