Search Results (34)

Electrochromic (EC) devices are gaining increasing attention for next-generation smart windows and low-power displays due to their reversible color modulation, low operating voltage, and flexible form factors. Recently, electrochromic energy storage devices (EESDs) have emerged as a promising class of multifunctional systems, enabling simultaneous energy storage and real-time visual monitoring. In this study, we report a flexible dual-functional EESD constructed using polyaniline (PANI) films doped with anthraquinone-1-sulfonic acid sodium salt (AQS), coupled with a redox-active PVA-based gel electrolyte also incorporating AQS. The incorporation of AQS into both the polymer matrix and the gel electrolyte introduces synergistic redox activity, facilitating bidirectional Faradaic reactions at the film–electrolyte interface and within the bulk gel phase. The resulting vertically aligned PANI-AQS nanoneedle films provide high surface area and efficient ion pathways, while the AQS-doped gel electrolyte contributes to enhanced ionic conductivity and electrochemical stability. The device exhibits rapid and reversible color switching from light green to deep black (within 2 s), along with a high areal capacitance of 194.2 mF·cm⁻² at 1 mA·cm⁻² and 72.1% capacitance retention over 5000 cycles—representing a 31.5% improvement over undoped systems. These results highlight the critical role of redox-functionalized gel electrolytes in enhancing both the energy storage and optical performance of EESDs, offering a scalable strategy for multifunctional, gel-based electrochemical systems in wearable and smart electronics. Full article

The design and investigation of electrochromic devices have advanced significantly, including distinct applications such as self-charged smart windows, aerospace interactive windows, low power flexible and ecofriendly displays, automatic dimming rearview, wearable smart textiles, military and civilian camouflage systems, electrochromic sensors, among others. Although significant progress has been made in related fields, achieving the full potential of electrochromic devices to meet the standards of maturity and practical applications remains a persistent challenge. Electrochromic devices are typically multilayered structures that can be designed as either rigid or flexible systems, depending on the type of substrate employed. Conventional electrochromic devices comprise layered structures that include transparent electrodes, electrochromic materials, ionic conductors, and ion storage materials. On the other hand, multifunctional systems integrate bifunctional materials or distinct functional layers to simultaneously achieve optical modulation and additional capabilities such as energy storage. The development of advanced materials, comprehensive electrochemical kinetic analysis, the optimization and advancement of process techniques and deposition methods, and innovative device designs are active areas of extensive global research. This review focuses on the recent advances in multifunctional electrochromic materials and devices with particular emphasis on the integration of electrochromic technology with other functional technologies. It further identifies current challenges, proposes potential solutions, and outlines future research directions focused on advancing this technology in both niche and scalable applications. Full article

Electrochromic supercapacitors (ECSCs), which visually indicate their operating status through color changes, have attracted considerable attention in the field of wearable electronics. The conductive polymer polyaniline (PANI) shows great potential for integrated intelligent devices by combining bi-functional electrochromic spectral modulation and energy storage capabilities. In this work, a microsphere-like structured PANI-based composite film was fabricated on a porous Au/nylon 66 electrode via a one-step electrochemical copolymerization process, using 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (PTSA) as both the dopant and cross-linking agent for the PANI backbone, serving as the ECSC electrode. Compared to the pristine PANI electrode, the PANI-PTSA composite film exhibits lower intrinsic resistance and higher electrical conductivity, delivering a higher specific capacitance of 310.0 F g⁻¹@1 A g⁻¹ and an areal capacitance of 340.0 mF cm⁻²@1 mA cm⁻², respectively. The dopant facilitates enhanced electrochemical performance by promoting charge transport within the PANI polymer network. Meanwhile, as a counter anion to the PANI backbone, PTSA regulates the growth of PANI chains and acts as a morphological controller. Furthermore, a symmetric ECSC based on the PANI-PTSA_8:1 electrode was assembled, and its electrochemical properties were thoroughly investigated. The device demonstrated a high specific capacitance of 169.2 mF cm⁻² at 1 mA cm⁻², a notable energy density of 23.5 μWh cm⁻² at a power density of 0.5 mW cm⁻², and excellent cycling stability with 79% capacitance retention after 3000 cycles at a current density of 5 mA cm⁻², alongside remarkable mechanical flexibility. Additionally, the working status of the ECSCs can be directly monitored through reversible color changes from yellow-green to deep blue during charge–discharge processes. Full article

Flexible electrochromic devices (ECDs) represent a distinctive category in optoelectronics, leveraging advanced materials to achieve tunable coloration under applied electric voltage. This review delves into recent advancements in electrode materials for ECDs, with a focus on silver nanowires, metal meshes, conductive polymers, carbon nanotubes, and transparent conductive ceramics. Each material is evaluated based on its manufacturing methods and integration potential. The analysis highlights the prominent role of transparent conductive ceramics and conductive polymers due to their versatility and scalability, while also addressing challenges such as environmental stability and production costs. Use of other alternative materials, such as metal meshes, carbon materials, nanowires and others, are presented here as a comparison as well. Emerging hybrid systems and advanced coating techniques are identified as promising solutions to overcome limitations regarding flexibility and durability. This review underscores the critical importance of electrode innovation in enhancing the performance, sustainability, and application scope of flexible ECDs for next-generation technologies. Full article

An integrated visual energy system consisting of conjugated polymer electrodes is promising for combining electrochromism with energy storage. In this work, we obtained copolymer bifunctional electrodes poly(3,6-dimethoxythieno[3,2-b]thiophene-co-2,3-dihydrothieno[3,4-b][1,4]dioxin-3-ylmethanol)(P(TT-OMe-co-EDTM)) by one-step electrochemical copolymerization, which exhibits favorable electrochromic and capacitive energy storage properties. Because of the synergistic effect of PTT-OMe and PEDTM, the prepared copolymers show better flexibility. Moreover, the morphology and electrochemical properties of the copolymers could be adjusted by depositing different molar ratios of 3,6-dimethoxythieno[3,2-b]thiophene (TT-OMe) and 2,3-dihydrothieno[3,4-b][1,4] dioxin-3-ylmethanol (EDTM). The P(TT-OMe-co-EDTM) electrodes realized a high specific capacitance (190 F/g at 5 mV/s) and recognizable color conversion. This work provides a novel and simple way to synergistically improve electrochromic and energy storage properties and develop thiophene-based conducting polymers for electrochromic energy storage devices. Full article

The sol-gel method is a widely adopted technique for the preparation of tungsten trioxide (WO₃) materials, favored for its cost-effectiveness and straightforward production procedures. However, this method encounters challenges such as prolonged annealing periods and limited flexibility in fabricating patterned WO₃ films. This study introduces a novel approach that integrates femtosecond laser processing with the sol-gel method to enhance the fabrication of WO₃ films. By adjusting polyvinylpyrrolidone (PVP) concentrations during sol-gel synthesis, precise control over film thickness and optimized film properties were achieved. The innovative technique significantly reduced the annealing time required to achieve an 80% transmittance rate from 90 min to 40 min, marking a 56% decrease. Laser processing increased the surface roughness of the films from Sa = 0.032 to Sa = 0.119, facilitating enhanced volatilization of organics during heat treatment. Additionally, this method improved the transmittance modulation of the films by 22% at 550 nm compared to unprocessed counterparts. This approach not only simplifies the manufacturing process but also enhances the optical efficiency of electrochromic devices, potentially leading to broader applications and more effective energy conservation strategies. Full article

SPECPs are electrochromic polymers that contain special engineering plastic structural characteristic groups (SPECPs). Due to their high thermal stability, mechanical properties, and weather resistance, they are also known as high-performance electrochromic polymer (HPEP or HPP). Meanwhile, due to the structural characteristics of their long polymer chains, these materials have natural advantages in the application of flexible electrochromic devices. According to the structure of special engineering plastic groups, SPECPs are divided into five categories: polyamide, polyimide, polyamide imide, polyarylsulfone, and polyarylketone. This article mainly introduces the latest research on SPECPs. The structural design, electrochromic properties, and applications of these materials are also introduced in this article, and the challenges and future development trends of SPECPs are prospected. Full article

In recent years, there has been a huge surge in interest in improving the efficiency of smart electronic and optoelectronic devices via the development of novel materials and printing technologies. Inkjet printing, known to deposit ‘ink on demand’, helps to reduce the consumption of materials. Printing inks on various substrates like paper, glass, and fabric is possible, generating flexible devices that include supercapacitors, sensors, and electrochromic devices. Newer inks being tested and used include formulations of carbon nanoparticles, photochromic dyes, conducting polymers, etc. Among the conducting polymers, PANI has been well researched. It can be synthesized and doped easily and allows for the easy formation of composite conductive inks. Doping and the addition of additives like metal salts, oxidants, and halide ions tune its electrical properties. PANI has a large specific capacitance and has been researched for its applications in supercapacitors. It has been used as a sensor for pH and humidity as well as a biosensor for sweat, blood, etc. The response is generated by a change in its electrical conductivity. This review paper presents an overview of the investigations on the formulation of the inks based on conductive polymers, mainly centered around PANI, and inkjet printing of its formulations for a variety of devices, including supercapacitors, sensors, electrochromic devices, and patterning on flexible substrates. It covers their performance characteristics and also presents a future perspective on inkjet printing technology for advanced electronic, optoelectronic, and other conductive-polymer-based devices. We believe this review provides a new direction for next-generation conductive-polymer-based devices for various applications. Full article

Nowadays, solid polymer electrolytes have attracted increasing attention for their wide electrochemical stability window, low cost, excellent processability, flexibility and low interfacial impedance. Specifically, gel polymer electrolytes (GPEs) are attractive substitutes for liquid ones due to their high ionic conductivity (10⁻³–10⁻² S cm⁻¹) at room temperature and solid-like dimensional stability with excellent flexibility. These characteristics make GPEs promising materials for electrochemical device applications, i.e., high-energy-density rechargeable batteries, supercapacitors, electrochromic displays, sensors, and actuators. The aim of this study is to demonstrate the viability of a sustainable GPE, prepared without using organic solvents or ionic liquids and with a simplified preparation route, that can substitute aqueous electrolytes in electrochemical devices operating at low voltages (up to 2 V). A polyvinyl alcohol (PVA)-based GPE has been cast from an aqueous solution and characterized with physicochemical and electrochemical methods. Its electrochemical stability has been assessed with capacitive electrodes in a supercapacitor configuration, and its good ionic conductivity and stability in the atmosphere in terms of water loss have been demonstrated. The feasibility of GPE in an electrochemical sensor configuration with a mediator embedded in an insulating polymer matrix (ferrocene/polyvinylidene difluoride system) has also been reported. Full article

The application potential of flexible electrochromic materials for wearable devices, smart textiles, flexible displays, electronic paper, and implantable biomedical devices is enormous. These materials offer the advantages of conformability and mechanical robustness, making them highly desirable for these applications. In this review, we comprehensively examine the field of flexible electrochromic materials, covering topics such as synthesis methods, structure design, electrochromic mechanisms, and current applications. We also address the challenges associated with achieving flexibility in electrochromic materials and discuss strategies to overcome them. By shedding light on these challenges and proposing solutions, we aim to advance the development of flexible electrochromic materials. We also highlight recent advances in the field and present promising directions for future research. We intend to stimulate further innovation and development in this rapidly evolving field and encourage researchers to explore new opportunities and applications for flexible electrochromic materials. Through this review, readers can gain a comprehensive understanding of the synthesis, design, mechanisms, and applications of flexible electrochromic materials. It serves as a valuable resource for researchers and industry professionals looking to harness the potential of these materials for various technological applications. Full article

The application of flexible indium tin oxide (ITO-free) electrochromic devices has steadily attracted widespread attention in wearable devices. Recently, silver nanowire/poly(dimethylsiloxane) (AgNW/PDMS)-based stretchable conductive films have raised great interest as ITO-free substrate for flexible electrochromic devices. However, it is still difficult to achieve high transparency with low resistance due to the weak binding force between AgNW and PDMS with low surface energy because of the possibility of detaching and sliding occurring at the interface. Herein, we propose a method to pattern the pre-cured PDMS (PT-PDMS) by stainless steel film as a template through constructed micron grooves and embedded structure, to prepare a stretchable AgNW/PT-PDMS electrode with high transparency and high conductivity. The stretchable AgNW/PT-PDMS electrode can be stretched (5000 cycles), twisted, and surface friction (3M tape for 500 cycles) without significant loss of conductivity (ΔR/R ≈ 16% and 27%). In addition, with the increase of stretch (stretching to 10–80%), the AgNW/PT-PDMS electrode transmittance increased, and the conductivity increased at first and then decreased. It is possible that the AgNWs in the micron grooves are spread during PDMS stretching, resulting in a larger spreading area and higher transmittance of the AgNWs film; at the same time, the nanowires between the grooves come into contact, thus increasing conductivity. An electrochromic electrode constructed with the stretchable AgNW/PT-PDMS exhibited excellent electrochromic behavior (transmittance contrast from ~61% to ~57%) even after 10,000 bending cycles or 500 stretching cycles, indicating high stability and mechanical robustness. Notably, this method of preparing transparent stretch electrodes based on patterned PDMS provides a promising solution for developing electronic devices with unique structures and high performance. Full article

Electrochromic (EC) windows on glass for thermal and glare protection in buildings, often referred to as smart (dimmable) windows, are commercially available, along with rearview mirrors or windows in aircraft cabins. Plastic-based applications, such as ski goggles, visors and car windows, that require lightweight, three-dimensional (3D) geometry and high-throughput manufacturing are still under development. To produce such EC devices (ECDs), a flexible EC film could be integrated into a back injection molding process, where the films are processed into compact 3D geometries in a single automized step at a low processing time. Polycarbonate (PC) as a substrate is a lightweight and robust alternative to glass due to its outstanding optical and mechanical properties. In this study, an EC film on a PC substrate was fabricated and characterized for the first time. To achieve a highly transmissive and colorless bright state, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) was used as the working electrode, while titanium dioxide (TiO₂) was used as the counter electrode material. They were deposited onto ITO-coated PC films using dip- and slot-die coating, respectively. The electrodes were optically and electrochemically characterized. An ECD with a polyurethane containing gel electrolyte was investigated with regard to optical properties, switching speed and cycling behavior. The ECD exhibits a color-neutral and highly transmissive bright state with a visible light transmittance of 74% and a bluish-colored state of 64%, a fast switching speed (7 s/4 s for bleaching/coloring) and a moderately stable cycling behavior over 500 cycles with a decrease in transmittance change from 10%to 7%. Full article

A recently described flexible polyurethane electrolyte was artificially weathered at 25/50 °C and 50% r.h. in air and at 25 °C in a dry nitrogen atmosphere, each with and without UV irradiation. Different formulations and the polymer matrix, used as a reference, were weathered in order to investigate the influence of the amount of conductive lithium salt and the solvent propylene carbonate. The complete loss of the solvent at a standard climate was already observed after a few days, strongly influencing the conductivity and mechanical properties. The essential degradation mechanism appears to be the photo-oxidative degradation of the polyol’s ether bonds, which leads to chain scission, oxidation products and negative changes in the mechanical and optical properties. A higher salt content has no effect on the degradation; however, the presence of propylene carbonate intensifies the degradation. Full article

Electrically conducting and semiconducting polymers represent a special and still very attractive class of functional chromophores, especially due to their unique optical and electronic properties and their broad device application potential. They are potentially suitable as materials for several applications of high future relevance, for example flexible photovoltaic modules, components of displays/screens and batteries, electrochromic windows, or photocatalysts. Therefore, their synthesis and structure elucidation are still intensely investigated. This article will demonstrate the very fruitful interplay of current electropolymerization research and its exploitation for science education issues. Experiments involving the synthesis of conducting polymers and their assembly into functional devices can be used to teach basic chemical and physical principles as well as to motivate students for an innovative and interdisciplinary field of chemistry. Full article

Two di-ureasils incorporating oxyethylene segments with average molecular weights Y = 600 and 900 g mol⁻¹, prepared by the sol-gel method, and doped with the ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) and lithium tetrafluoroborate (LiBF₄) salt were prepared. The as-obtained films are translucent, flexible, and hydrophobic, and have a low level of nanoscale surface roughness. The ionic conductivity values exhibited by an optimized sample are 8.10 × 10⁻⁵ and 2.8 × 10⁻⁴ S cm⁻¹ at room temperature and 55 °C, respectively. The main goal of the work was to employ the electrolytes in prototype electrochromic devices (ECDs) with the [glass/a-IZO/a-WO₃/d-U(Y)LiBF₄-[Bmim]Cl/c-NiO/a-IZO/glass], noted as ECD1 for Y = 600 and ECD2 for Y = 900, where a-WO₃ and c-NiO stand for amorphous tungsten oxide and crystalline nickel oxide, respectively. At 555 nm the ECD1 device exhibited the highest coloration efficiency for coloring (CE_in = −420.621 cm²·C⁻¹), the highest optical density value (∆(OD) = 0.13) and good cycling stability. In this article, the results of a preliminary evaluation of hybrid electrolytes, produced by a sol-gel process, as multi-functional components in prototype electrochromic devices are reported. Full article