Search Results (80)

Flexible, intelligent color-changing windows with excellent color-switching capability and fast response time rely significantly on conductive composite layers composed of electrochromic materials and flexible, transparent substrates. Herein, we developed a high-performance electrochromic film (CPC) with mechanical, humidity, and temperature insensitivity by coating sodium carboxymethyl cellulose (CMC)-dispersed PEDOT:PSS onto a CA film. In the CPC system, CMC not only effectively enhances interfacial bonding and compatibility between the hydrophobic CA film and the hydrophilic PEDOT:PSS but also enables uniform and stable deposition of PEDOT:PSS on the CA film. As a result, the designed CPC demonstrates a high optical modulation capability (the transmittance changes from 60.1% to 3%) and a response time of 2 s. In addition, the CPC features the advantages of mechanical-, humidity-, and temperature-insensitive electrochromic distinctions, where it outputs the stable coloring efficiency with 100-time bending treatment, various temperatures, and humidity in an all-day outdoor environment. The developed CPC electrochromic film offers new insights into promoting the structural simplification and sustainability of electrochromic materials. Full article

Polyaniline (PANI), characterized by its proton-coupled redox mechanism and multicolor reversibility, is widely investigated for adaptive optical interfaces. Compared to inorganic oxides, PANI offers advantages in cost-effectiveness, mechanical flexibility, and molecular tunability; however, its practical implementation faces challenges related to kinetic limitations and environmental instability. This review presents a comprehensive analysis of PANI-based electrochromic materials, examining the intrinsic correlations among synthesis methodologies, microstructural characteristics, and optoelectronic performance. Synthesis strategies, including chemical oxidative polymerization, electrochemical deposition, and template-assisted techniques, are evaluated. Emphasis is placed on resolving the trade-off between optical contrast and switching kinetics by constructing high-surface-area porous nanostructures and inducing chain ordering via functional dopants to shorten ion diffusion paths and reduce charge transfer resistance. Fundamental electrochromic properties are subsequently discussed, with specific attention to degradation mechanisms triggered by environmental factors, such as pH drift, and stabilization strategies involving electrolyte engineering and composite design. Furthermore, the review addresses the evolution of applications from single-band monochromatic displays to dual-band smart windows for decoupled visible/near-infrared regulation and multifunctional integrated systems, including electrochromic supercapacitors and adaptive thermal management textiles. Finally, technical challenges regarding long-term durability, neutral color development, and large-area manufacturing are summarized to outline future research directions for PANI-based optical systems. Full article

Two amide-preformed aromatic diamine monomers, N,N-bis(4-(3-aminobenzamido)phenyl)-N’,N’-bis(4-methoxyphenyl)-1,4-phenylenediamine (m-6) and N,N-bis(4-(4-aminobenzamido)phenyl)-N’,N’-bis(4-methoxyphenyl)-1,4-phenylenediamine (p-6), were synthesized and utilized to prepare two series of electroactive poly(amide-imide)s (PAIs) through a two-step polycondensation reaction with commercially available aromatic tetracarboxylic dianhydrides. The obtained polymers exhibited solubility in various polar organic solvents, and most of them could form transparent, flexible films via solution casting. Thermal analysis indicated glass transition temperatures (T_g) ranging from 250 °C to 277 °C, as measured by DSC, with no significant weight loss observed before 400 °C in TGA tests. Cyclic voltammograms (CV) of the polymer films on ITO-coated glass substrates revealed two reversible oxidation redox pairs between 0.67 and 1.04 V vs. Ag/AgCl in an electrolyte-containing acetonitrile solution. The PAI films showed stable redox activity with high optical contrast both in the visible and near-infrared regions, transitioning from colorless in the neutral state to green and blue in the oxidized states. Furthermore, the polymer films retained good electrochemical and electrochromic stability even after more than 100 cyclic switching operations. The PAIs displayed outstanding electrochromic performance, including high optical contrast (up to 95%), rapid response times (below 4.6 s for coloring and 5.7 s for bleaching), high coloration efficiency (up to 240 cm²/C), and low decay in optical contrast (less than 5% after 100 switching cycles for most PAIs). Full article

In order to improve the electrochromic performance of polyaniline (PANI), porous PANI/vanadium carbide MXene (PANI/V₂CT_x) composite electrochromic films were prepared via a rapid, facile, and low-cost one-pot electrodeposition method from an aqueous solution composed of aniline and V₂CT_x for the first time. The addition of V₂CT_x with a 2D layered structure results in the PANI/V₂CT_x composite films exhibiting significantly different morphologies, structures, electrochemical and electrochromic properties from the pure PANI film. The results show that compared with the pure PANI film, the composite film with optimum V₂CT_x content possesses superior electrochromic properties, such as higher optical contrast, switching speed, coloration efficiency, and cycling stability. The improved electrochromic properties of the composite film can be ascribed to its unique porous morphology and strong hydrogen bond and/or electrostatic interaction between PANI and V₂CT_x. This research demonstrates that the one-pot electrodeposition method and the prepared conductive PANI/MXene composite films have potential applications in various fields. Full article

In this work, we report the divergent synthesis of a novel corrole macrocycle with a T-shaped geometry, functionalized with triphenylamine (TPA) units. The synthetic route involved a green preparation of 5-(pentafluorophenyl)dipyrromethane, condensation with pentafluorobenzaldehyde, and DDQ oxidation to afford the target corrole. In parallel, a TPA-based chalcone derivative was obtained and introduced via regioselective nucleophilic aromatic substitution. The resulting photoactive corrole–TPA conjugate exhibited efficient electropolymerization, retaining the corrole chromophore while forming conductive TPB-linked films (TPB, tetraphenylbenzidine). Spectroelectrochemical studies confirmed reversible redox activity, color switching, and electrochromic behavior, highlighting its potential as a building block for photo- and electroactive devices. Full article

With continuous breakthroughs in electrochromic technology, tungsten trioxide (WO₃) thin films, as a core material in this field, are rapidly expanding their applications in smart windows, anti-glare automotive rearview mirrors, and adaptive optical lenses. Owing to its excellent electrochromic properties—including high optical modulation, short switching times, and high coloration efficiency—WO₃ has become a research focus in the field of electrochromic devices. This review takes WO₃ thin films as the research subject. It begins by introducing the crystal structure of WO₃ and the ion/electron co-intercalation-based electrochromic mechanism and explains two key performance parameters for evaluating electrochromic properties: optical modulation amplitude and coloration efficiency. Subsequently, it provides a detailed review of recent advances in the preparation of WO₃ thin films via physical methods (including sputtering deposition, evaporative deposition, and pulsed laser deposition) and chemical methods (including hydrothermal, sol–gel, and electrodeposition methods). A systematic comparison is made of the microstructure and electrochromic performance (optical modulation amplitude and coloration efficiency) of films prepared by different methods, and the interaction between WO₃ film morphology and device structure is analyzed. Finally, the advantages and challenges of physical and chemical methods in tuning film properties are summarized, and the outlook of their application prospects in high-performance electrochromic devices is given. This review aims to provide guidance for the selection and process optimization of WO₃ thin films with enhanced performance for applications such as smart windows, anti-glare rearview mirrors, and adaptive optical systems. Full article

In this study, two novel hybrid monomers (4BD-EDOT and 3BD-EDOT) containing a biphenyl group and a 3,4-ethylenedioxythiophene (EDOT) unit were synthesized and polymerized electrochemically in a CH₂Cl₂-Bu₄NPF₆ electrolyte solution. Characterizations of the resulting P4BD-EDOT and P3BD-EDOT were studied by CV, scanning electron microscopy (SEM), and spectroelectrochemistry in order to examine the effect of different substitution positions of biphenyl on the electrochromic performance of the resultant hybrid polymers. Both polymers have favorable redox activity (a distinct redox peak) and good redox stability (55–49% electroactivity was retained after 1000 cycles). The spectro-electrochemistry study found that both show a distinct color change from reddish brown to blue/purple for P4BD-EDOT with a lower band gap (1.54 eV) and from transparent color to light blue for P3BD-EDOT with a larger band gap (1.73 eV). These electrochromic polymer films also have fast switching speed (0.5–0.2 s), with the favorable optical contrast (22.6% at 1100 nm for P4BD-EDOT) and decent coloration efficiency (250.4 cm² C⁻¹ at 780 nm for P3BD-EDOT). All these results show that both monomers have important values related to the electrochromic field. This work also shows that the different substitution positions of the biphenyl unit affect the spectroelectrochemistry and electrochromic characteristics of the resultant hybrid polymers. Full article

Viologens are promising candidates for next-generation electrochromic devices due to their reversible color changes, low operating voltages, and structural tunability. However, their practical performance is often constrained by limited color range, stability issues, and poor charge delocalization. In this study, we present a detailed density functional theory (DFT) and time-dependent DFT (TD-DFT) investigation of asymmetric viologens based on the Benzyl-4,4′-dipyridyl-R (BnV-R) framework. A series of electron-donating and electron-withdrawing substituents (CN, COOH, PO₃H₂, CH₃, OH, NH₂) were introduced via either benzyl or phenyl linkers. Geometry optimizations for neutral, radical cationic, and dicationic states were performed at the CAM-B3LYP/6-31+G(d,p) level with C-PCM solvent modeling. Electronic structure, frontier orbital distributions, and redox potentials were correlated with substituent type and linkage mode. Natural Bond Orbital analysis showed that electron-withdrawing groups stabilize reduced states, while electron-donating groups enhance intramolecular charge transfer and switching kinetics. TD-DFT calculations revealed significant bathochromic and hyperchromic shifts dependent on substitution patterns, with phenyl linkers promoting extended conjugation and benzyl spacers minimizing aggregation. Radical cation stability, quantified via ΔE_red and comproportionation constants, highlighted cyano- and amine-substituted systems as particularly promising. These insights provide predictive design guidelines for tuning optical contrast, coloration efficiency, and electrochemical durability in advanced electrochromic applications. Full article

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

In response to escalating global energy demands and environmental challenges, electrochromic (EC) smart windows have emerged as a transformative technology for adaptive solar modulation. Herein, we report the rational design and fabrication of a bilayer WO₃/TiO₂ heterostructure via a synergistic two-step strategy involving the electrochemical deposition of amorphous WO₃ and the controlled hydrothermal crystallization of TiO₂. Structural and morphological analyses confirm the formation of phase-pure heterostructures with a tunable TiO₂ crystallinity governed by reaction time. The optimized WTi-5 configuration exhibits a hierarchically organized nanostructure that couples the fast ion intercalation dynamics of amorphous WO₃ with the interfacial stability and electrochemical modulation capability of crystalline TiO₂. Electrochromic characterization reveals pronounced redox activity, a high charge reversibility (98.48%), and superior coloration efficiency (128.93 cm²/C). Optical analysis confirms an exceptional transmittance modulation (ΔT = 82.16% at 600 nm) and rapid switching kinetics (coloration/bleaching times of 15.4 s and 6.2 s, respectively). A large-area EC device constructed with the WTi-5 electrode delivers durable performance, with only a 3.13% degradation over extended cycling. This study establishes interface-engineered WO₃/TiO₂ bilayers as a scalable platform for next-generation smart windows, highlighting the pivotal role of a heterostructure design in uniting a high contrast, speed, and longevity within a single EC architecture. Full article

The development of high-performance electrochromic materials demands innovative approaches to simultaneously control the nanoscale architecture and the electronic structure. We present a dual-modification strategy that synergistically combines copper doping with the Langmuir–Blodgett (LB) assembly to overcome the traditional performance trade-offs in tungsten oxide-based electrochromic systems. Cu-doped W₁₈O₄₉ nanowires with varying Cu concentrations (0–12 mol%) were synthesized hydrothermally and assembled into thin films via the LB technique, with LB precursors characterized by contact angle, surface tension, viscosity, and thermogravimetric-differential scanning calorimetry (TG-DSC) analyses. The films were systematically evaluated using scanning electron microscopy, X-ray photoelectron spectroscopy, chronoamperometry, and transmittance spectroscopy. Experimental results reveal an optimal Cu-doping concentration of 8 mol%, achieving a near-infrared optical modulation amplitude of 76.24% at 1066 nm, rapid switching kinetics (coloring/bleaching: 5.0/3.0 s), and a coloration efficiency of 133.00 cm²/C. This performance is speculated to be a balance between Cu-induced improvements in ion intercalation kinetics and LB-ordering degradation caused by lattice strain and interfacial charge redistribution, while mitigating excessive doping effects such as structural deterioration and thermodynamic instability. The work establishes a dual-modification framework for designing high-performance electrochromic interfaces, emphasizing the critical role of surface chemistry and nanoscale assembly in advancing adaptive optoelectronic devices like smart windows. Full article

The electrochromic naphthalenediimide (NDI) based monomer containing styrene pedant groups, which are capable of polymerization, was prepared, and the formation of its polymer via a photopolymerization reaction was described. Both the monomer and polymer exhibited a color change in the visible range from transparent or slightly yellow, respectively, followed by brown-red to green. This was the result of a two-step reduction reaction of NDI core to radical anion and dianion, respectively. The device constructed using the polymer as an active material was found to exhibit good electrochromic stability over 500 redox cycles. The switching times were calculated to be 18 s and 6 s for the coloration and bleaching steps, respectively. The presented results showed the usability of the photopolymerization of styrene-based monomers in the generation of the stable electrochromic layers of polymers. Full article

WO₃ electrochromic films have emerged as potential candidates for smart windows due to their cost-effectiveness, fast switching speed, and strong chemical stability. However, the inherent contradiction between the high coloring efficiency of amorphous WO₃ and the cycling durability of crystalline WO₃ remains a critical challenge in practical applications. This study proposes an innovative heterostructure engineering strategy, achieving precise control of the amorphous/crystalline bilayer WO₃ heterointerface (148 nm a-WO₃/115 nm c-WO₃) for the first time through phase boundary regulation, using well-controlled magnetron sputtering and post-deposition thermal annealing processes. Multimodal characterization using XRD, XPS, and SEM indicates that the heterointerface optimizes performance through a dynamic charge transfer mechanism and structural synergistic effects: the optimized bilayer structure achieves 76.57% optical modulation (at 630 nm) under −1.0 V and maintains a ΔT retention rate of 45.02% after 600 cycles, significantly outperforming single amorphous (8.34%) and crystalline films (14.34%). XPS analysis reveals a dynamic equilibrium mechanism involving W⁵⁺/Li⁺ at the interface, and the Li⁺ diffusion coefficient (D₀ = 4.29 × 10⁻¹⁰ cm²/s) confirms that the amorphous layer dominates rapid ion transport, while the crystalline matrix enhances structural stability through its ordered crystalline structure. This study offers a new paradigm for balancing the efficiency and longevity of electrochromic devices, with the compatibility of magnetic sputtering promoting the industrialization process of large-area smart windows. Full article

Electrochromic devices (ECDs) are devices that change their optical properties in response to a low applied voltage. These devices typically consist of an electrochromic layer, a transparent conducting substrate, and an electrolyte. The advancement in solid-state ECDs has been driven by the need for improved durability, optical performance, and energy efficiency. In this study, we investigate varying the temperature to the casting solution for polymethylmethacrylate (PMMA)-based electrolytes for solid-state ECDs with a structure of glass/ITO/WO₃/PMMA electrolyte/ITO/glass. The electrochromic layer, composed of WO₃, was deposited using the sol-gel method, while the electrolyte, comprising lithium perchlorate (LiClO₄) in propylene carbonate (PC) with PMMA, was prepared via solution casting. Various electrolyte samples were heated at different temperatures of 25, 40, 60, 80, and 100 °C to analyze the impact on the devices’ performance. Our findings indicate that the devices with electrolytes at 25 °C exhibited superior anodic and cathodic diffusion. An increase in heating temperature corresponded with an increase in switching time. Notably, the sample heated at higher temperatures (60, 80, and 100 °C) demonstrated exceptional cycle stability. Nevertheless, samples with higher temperatures displayed a decrease in optical modulation. Additionally, the 100 °C sample exhibited the highest coloration efficiency compared to other samples at lower temperatures. This research highlights the potential of varying the temperature of solution casting on PMMA-based electrolytes in optimizing the performance of solid-state ECDs, particularly regarding coloration efficiency and durability. Full article

In this article, a series of novel conducting copolymers P(FuPy-co-EDOT) are prepared via cyclic voltammetry electropolymerization method by using N-furfuryl pyrrole (FuPy) and 3,4-ethylenedioxythiophene (EDOT) as comonomers. The molecular structure, surface morphology, electrochemical, and optical properties of the resulting copolymers are characterized in detail upon varying the feed ratios of FuPy/EDOT in the range of 1/1 to 1/9. The results demonstrate that the prepared P(FuPy-co-EDOT) copolymers with a higher proportion of EDOT units (FuPy/EDOT: 2/8~1/9) possess good redox activity, tunable optical absorption performances, and low band gaps (1.75~1.86 eV). Spectroelectrochemistry studies indicate that the resulting copolymers with increased EDOT units show strengthened electrochromic characteristics, exhibiting a red-to-green-to-blue multicolor reversible transition, especially for the P(FuPy₁-co-EDOT₉) copolymer films. They also show increased optical contrast (9~34%), fast response time (0.8~2.4 s), and good coloring efficiency (110~362 cm² C⁻¹). Additionally, the complementary bilayer P(FuPy-co-EDOT)/PEDOT electrochromic devices (ECDs) are also assembled and evaluated to hold excellent electrochromic switching performances with relatively high optical contrast (25%), rapid response time (0.9 s), and satisfactory coloring efficiency (416 cm² C⁻¹). Together with the superior open circuit memory and cycling stability, they can be used as a new type of electrochromic material and have considerable prospects as promising candidates for electrochromic devices. Full article