Application In Electrochromic Devices Research Articles

Influence of H2 on the properties of NiOxHy thin films deposited by reactive direct current magnetron sputtering for electrochromic devices

This study aims to optimize the deposition condition of Nickel hydroxide (NiOxHy) films for electrochromic devices by adjusting the H2 gas concentration during the reactive direct current magnetron sputtering. The influence of H2 content on the crystallinity, chemical composition, optical properties, and electrochromic behavior of the NiOxHy films was thoroughly investigated. In the absence of H2 gas in the sputtering system, the Nickel oxide (NiOx) film was obtained as confirmed by the X-ray diffraction results. However, introducing the H2 gas resulted in the formation of NiOxHy film, accompanied by a decrease in the film crystallinity. Fourier transform Infrared spectra were employed to confirm the presence of hydroxyl groups in the as-deposited NiOxHy films. X-ray photoelectron spectroscopy was employed to examine the influence of H2 content on the optical properties of the NiOxHy film. Additionally, it offered valuable insights into the film's chemical composition during the transition from a dark to a transparent state. Our findings revealed that increasing the H2 gas content enhanced the transmittance of NiOxHy films. Here, the optimal H2 flow ratio of 50 % was found to yield a high transmittance of 77.43 % (T550) along with the highest charge density, an optical density changed value of 0.84, and a coloration efficiency value of 83.67 cm2/C. These findings clearly illustrate the substantial influence of H2 concentration on the properties of NiOxHy films, particularly in relation to their application in electrochromic devices.

Stable aryl-armed dihydrophenazines-based radicals

Stable organic radicals have long been desired for applications in quantum information science and optoelectronic semiconductor. Weakening the reactivity of unpaired electrons is an efficient strategy for fabrication stable radicals. The dual aryl/alkyl-substituted dihydrophenazine (DArPZ/DAlPz) derivatives have attracted a lot of attention due to their potential radical stability characteristics. In this work, three stable DArPZ-based radical cation compounds are obtained through tuning peripheral substituted groups with different electron donating/withdrawing effect to discuss their reactive activity changes in different solvent and aggregate state. Employing systematic experiments from crystallography, spectroscopy and theoretical calculation analyses, some referenceable molecular structure design strategy and the analytical model of evaluating radical behavior are formed and summarized. In addition, radical cations have good masking ability without continuous electrical circulating, implying their application in light-shading electrochromic devices. This work is referable on the design of stable radicals, the establishment of dynamic evaluation strategies and theoretical analysis models for their reactivity.

Preparation and properties of rGO-Co-NiO composite films: Low attenuation and high coloration efficiency

The study of electrochromic materials has far-reaching significance for the regulation of light and heat as well as the reduction of energy consumption. In this study, rGO-Co-NiO composite films were prepared by combining graphene oxide, which has excellent conductivity and stability, with Co-NiO films. The particle size, band gap, conductivity and response time of the electrochromic films were improved by precisely adjusting the component modulation amount of graphene oxide. The results show that with the incorporation of GO it is easy to form oxygen vacancies, which is conducive to ionic conduction and diffusion, in which the film with a GO doping concentration of 4 % has excellent performances in terms of response time and coloring efficiency, and the response time is reduced from 10.2 to 5.8 seconds, and it still possesses 57.25 % of the light modulation amplitude after 600 cycles, of which the attenuation rate is only 2 % for the period from 100 to 600 cycles, The coloring efficiency after 100 cycles is 48.21 cm2/C. In summary, the investigated rGO-Co-NiO composite films have a broad potential for future application in electrochromic devices.

Recent advances in multifunctional electrochromic devices

AbstractElectrochromic (EC) technology has been regarded as a promising energy‐saving technology in various applications, including smart windows, displays, thermal management, rear views, etc. Benefiting from the progress in electrochromic material synthesis, electrochromic electrode fabrication, and electrochromic device configuration design, the focus in electrochromic community has gradually shifted to multifunctional electrochromic devices (ECDs) in the era of Internet of Things. Multifunctional ECDs, such as electrochromic energy storage devices, multi‐color displays, deformable ECDs, smart windows, etc. have been showcased the ability to expand potential applications. In this review, the available device configurations, performance indexes and advanced characterization techniques for multifunctional ECDs are introduced and classified accordingly. The applications of multifunctional ECDs for energy storage, multicolor displays, deformable devices, self‐chargeable devices, smart windows, actuators, etc., are exemplified. The future development trends and perspectives of multifunctional ECDs are also overlooked. The aim of this review is to guide and inspire further efforts in the exploration of novel and advanced multifunctional ECDs.

Performance Optimization for Multicolor Electrochromic Devices: Morphology and Composition Regulation of Inorganic Electrochromic Materials and Selectivity of Ions

AbstractIn recent years, multicolor electrochromic devices (ECDs) have attracted much attention due to their application potential for rich color similar to RGB mode. Although organic electrochromic (EC) materials are widely used in multicolor electrochromism because of their multicolor properties, remarkable weatherability remains challenging. Inorganic EC materials especially transition metal oxide are particularly attractive for excellent weatherability in ECD fabrication. Moreover, by selection of electrolytes, better ionic transfer efficiency can be rendered in the EC process. Although the morphology regulation of the EC film and the selection of electrolytes in the ion transmission layer play important roles in optimizing EC performance and have been extensively studied, a systematic and comprehensive review is lacking. In this review, the morphology regulation of the EC film and selection rules of electrolytes in the multicolor ECDs is focused, and the advantages and disadvantages of existing ways are discussed. The current application of multicolor ECDs is also outlined and it is hoped that this review can contribute some inspiration to designing and improving multicolor ECDs.

Synthesis of bridged dinaphthoviologen derivatives for enhanced electrochromic performance and picric acid detection

Electrochromic materials represent a class of highly promising smart materials in contemporary research. Viologen, as a prevalent organic small molecule in smart chromic materials, has garnered extensive attention due to its tunable intermediate structure involving pyridine units and diverse nitrogen atom substituents. In this investigation, the molecular structure of dinaphthoviologen (DNV2+) were modified, and various groups were introduced to ionize nitrogen atoms. This structural modification aimed to decrease the molecular energy gap and enhance the electron acceptability of nitrogen atoms. The results demonstrate robust redox ability in DNV2+. To explore the practical applications, a straightforward DNV2+-based electrochromic device was fabricated, incorporating ferrocene as an electronic supplement. This device exhibited commendable cycling performance (exceeding 1000 cycles) and rapid response times (8 s for coloring and 10 s for fading) without the need for additional electrolytes. Additionally, the transmittance changes by more than 45 %. Moreover, owing to the presence of conjugated structures, DNV2+ exhibited noteworthy fluorescence properties. In fluorescence-based picric acid detection experiments, the synthesized molecules exhibited high selectivity and sensitivity, as evidenced by the determined Stern–Volmer constants (K6b = 2.17 × 104 L/mol, K6c = 3.87 × 104 L/mol). The findings highlight the potential of the developed dinaphthoviologen derivatives for advanced applications in electrochromic devices and sensitive detection of picric acid.

Inkjet printing for smart electrochromic devices

AbstractElectrochromic technology has recently made many achievements in research and commercialization. Electrochromic devices are being developed based on various coating and printing methods for multipronged applications, and have great potential for next‐generation flexible electronics. Compared to other coating and printing techniques, inkjet printing (IJP) enables non‐contact patterning on a variety of substrates by programming the movement of the printing nozzle. IJP has great advantages in printing smart electrochromic devices because of its low cost, high resolution, high material utilization rate, and applicability to various large‐size substrates. In this review, the principles and process of IJP and the latest progress of IJP in electrochromic devices are summarized in detail. IJP of electrochromic materials, conductive contacts, and blocking layers are discussed. IJP assisted fabrication of smart electrochromic displays, flexible and stretchable electrochromic devices, electrochromic‐energy storage, smart windows, and others are also demonstrated. The problems and challenges faced by IJP electrochromic devices are emphasized, and the future development trends are prospected. This review aims at further promoting the development of IJP for smart electrochromic devices and encouraging future applications of IJP and electrochromic devices in the era of Internet of Things.

Hole-transporting materials boost optoelectronic performance: Their first application in electrochromic device based on 1,1′-Bis(3-sulfopropyl) viologen

In this paper, we present the first application of organic hole-transporting semiconductors 4,4′,4′'-tris(carbazol-9-yl)triphenylamine (TCTA) and 4,4′-cyclohexylbis[N,N-bis(4-methylphenyl) aniline] (TAPC) in electrochromism area, demonstrating that TCTA or TAPC is suitable for use as hole-transporting materials on the anode of 1,1′-bis(3-sulfopropyl) viologen (SPV)-based electrochromic devices. For such devices, we obtain a decreased driving voltage of SPV-based electrochromic devices down to −2.0 V in the presence of TCTA or TAPC with comparison to that of ca. −2.5 V in the absence of the hole-transporting material. The optical contrast of the device increased from 57.19 % (without hole-transport layer) to 66.41 % (TCTA) or 62.97 % (TAPC) at 533 nm. The response time of 66.2 s in the absence of hole-transporting layer can decrease to 30.6 s with TCTA and 62.7 s with TAPC, respectively. The coloration efficiency of the as-fabricated devices at 533 nm can reach from 67.3 cm2/C (SPV-only) up to 153.2 cm2/C (TCTA) and 80.5 cm2/C (TAPC). This work paved a new way for boosting electrochromic performances of viologen-based devices via electrode modification of anode by hole-transporting material TCTA and TAPC which have been used effectively and efficiently in organic electroluminescent devices and solar cells.

Vis‐NIR Modulation in a Dynamically Reversible Single C‐pBPV Biopolymer Electrolyte for Sustainable Systems in Electrochromism

AbstractIn the pursuit of sustainable technology, the synthesis of a novel biopolymer, C‐pBPV, through the polymerization of carboxymethyl cellulose sodium salt (CMC‐Na) and viologen (BPV), with ammonium persulfate as an initiator is presented. This groundbreaking process not only promises an eco‐friendly approach but also opens avenues for advanced applications in electrochromic devices (ECDs), particularly in smart windows, displays, and beyond. Departing from conventional multi‐layered approaches, the study underscores the significance of a single‐layer material. C‐pBPV serves both as an electro‐chrome and an electrolyte, making it a compelling material for ECDs. It is used to create a gel‐based electrochromic device G1 with exceptional bistable properties. Following, a systematically controllable device, G2 is accomplished, to enhance color‐switching capabilities by adding vitamin C as an electron mediator. Both devices exhibited outstanding electrochromic properties, showcasing dual‐band absorption in the Vis‐NIR region, with color transitions from transparency to a striking purple state at low voltages. Embracing an all‐in‐one layer configuration, this study set the stage for next‐generation smart windows that not only regulate solar light for energy conservation but also pioneer a more compact, user‐friendly design, prioritizing visual comfort, sustainability, and a tailored user experience.

Preparation of electrospun polyacrylonıtrile (PAN) nanofıber membrane gel electrolyte and its application in TiO2-based electrochromic devices

Preparation of electrospun polyacrylonıtrile (PAN) nanofıber membrane gel electrolyte and its application in TiO2-based electrochromic devices

Multicolor reversible prussian white film with application in self-powered electrochromic device

The Prussian white film exhibits reversible multicolor conversion of transparent ↔ blue ↔ green ↔ yellow, and the self-powered electrochromic device with the system of Zn||PW||Pt@CC displays quick response speed and high reversibility.

Organic Mixed Ionic-Electronic Conductors for Bioelectronic Sensors: Materials and Operation Mechanisms.

The field of organic mixed ionic-electronic conductors (OMIECs) has gained significant attention due to their ability to transport both electrons and ions, making them promising candidates for various applications. Initially focused on inorganic materials, the exploration of mixed conduction has expanded to organic materials, especially polymers, owing to their advantages such as solution processability, flexibility, and property tunability. OMIECs, particularly in the form of polymers, possess both electronic and ionic transport functionalities. This review provides an overview of OMIECs in various aspects covering mechanisms of charge transport including electronic transport, ionic transport, and ionic-electronic coupling, as well as conducting/semiconducting conjugated polymers and their applications in organic bioelectronics, including (multi)sensors, neuromorphic devices, and electrochromic devices. OMIECs show promise in organic bioelectronics due to their compatibility with biological systems and the ability to modulate electronic conduction and ionic transport, resembling the principles of biological systems. Organic electrochemical transistors (OECTs) based on OMIECs offer significant potential for bioelectronic applications, responding to external stimuli through modulation of ionic transport. An in-depth review of recent research achievements in organic bioelectronic applications using OMIECs, categorized based on physical and chemical stimuli as well as neuromorphic devices and circuit applications, is presented.

Research Progress in Special Engineering Plastic-Based Electrochromic Polymers.

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.

Electrochromic properties of Ni or Ti single-doped and Ni-Ag or Ti-Ag binary-doped WO3 thin films

In this paper, the single-doped (Ni-WO3 and Ti-WO3) and binary-doped (Ni-Ag-WO3 and Ti-Ag-WO3) amorphous WO3 thin films were respectively prepared on indium-doped tin oxide conductive glass substrates by radio-frequency magnetron sputtering. Among the single-doped WO3 thin films, the electrochromic (EC) properties of films can be enhanced by the presence of Ni or Ti. However, the low conductivity of WO3 limits its application in EC devices. A novel approach was proposed to ameliorate this disadvantage which has not been explored, that is, the highly conductive Ag was introduced into WO3 films with Ni or Ti. The experimental results show that the addition of Ag reduces the charge transfer resistance and shortens the ion diffusion path length, thereby improving the EC response time (Ni-Ag-WO3: tb=1.16 s; Ti-Ag-WO3:tc=4.14 s), electrochemical active area, and ion diffusion coefficients (Ni-Ag-WO3: Da =3.032 × 10−9 cm2/s; Ti-Ag-WO3: Dc=7.737 × 10−9 cm2/s). Based on these work, the feasibility of Ni-Ag and Ti-Ag binary-doped WO3 films was confirmed. These discoveries contribute to the exploration of preparing high-performance WO3 EC films for the practical applications of EC devices such as in automatic anti-glare rearview mirrors.

Facile, low-cost and scalable preparation of V2O5/PEDOT:PSS inks for solution-processed multicolor electrochromic films

Poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid) (PEDOT:PSS) is extensively used as a commercial ink for electrochromic coatings. However, PEDOT:PSS film has the defect of a single color change, which limits the wide range of applications. The development of hybrid electrochromic inks containing PEDOT:PSS has attracted considerable attention attributed to their high electrical conductivity, large optical modulation, excellent cycling stability and multicolor variation. In this work, the color range of electrochromic PEDOT:PSS ink was adjusted by a simple and low-cost solution blending process method. The solution-processable multicolor vanadium pentoxide (V2O5) nanoribbons synthesized by a facile solution treatment process were used as additives to enlarge the color range of PEDOT:PSS ink. The electrochromic performance of V2O5-PEDOT:PSS hybrid films with V2O5 nanoribbon inclusions ranging from 0 wt% to 100 wt% was systematically studied. Our results demonstrate that the V2O5/PEDOT:PSS hybrid film can combine the color range of mixing inorganic and organic electrochromic materials. The spray-coated hybrid film with 40 % V2O5 nanoribbon (40VPE) shows a reversible multicolor change ranging from navy blue, yellow-green, orange, grey to blue. Moreover, the 40VPE hybrid film also exhibits high optical contrast (50.2 % at 660 nm), rapid response speed (2.7/3.8 s) and excellent cycling stability (sustaining 97 % of initial contrast after 100 cycles). The solution-processable and large-scale V2O5-PEDOT:PSS hybrid inks exhibit promising applications in multicolor electrochromic devices.

Synthesis and characterization of novel P3HT-CuO composites for their application in electrochromic devices

Novel poly(3-hexylthiophene-2,5-diyl) (P3HT)-copper oxide (CuO) composites were synthesized. The influence of the synthesis method (in-situ oxidation and simple mixing) and CuO concentration (3, 5, and 8 wt% CuO) on the properties of the composite was investigated. CuO was synthesized using the chemical bath technique. P3HT, CuO and P3HT-CuO composites were characterized by FT-IR, UV-Vis, XRD, FESEM and cyclic voltammetry. With the incorporation of CuO in P3HT it was possible to increase the absorbance using the synthesis method by simple mixture, however, by the in-situ method the absorbance was reduced. Likewise, with the incorporation of CuO in P3HT in both methods, the charge storage in the polymeric films increased. The composites showed enhanced electrochromic properties, which depend on the CuO concentration in the composites. The obtained composites were tested in single electrochromic devices using the ITO/(P3HT or COMPOSITE)/ELECTROLYTE/ITO configuration. It is shown that with the incorporation of CuO in P3HT the optical contrast can be increased, depending on both the synthesis method and the CuO concentration in the composites.

Rapid and low-temperature preparation of tungsten oxide electrochromic thin films by oxygen plasma treatment

Electrochromic materials have attracted considerable attention due to their ability to change color reversibly and rapidly under an external electrical stimulus, making them highly promising for use in various applications such as smart windows, displays, and optical memory devices. In particular, tungsten trioxide (WO3) thin films have shown excellent electrochromic properties, leading to their wide application in electrochromic devices. In this study, oxygen plasma treatment was used to convert WCl6 thin film to WO3 electrochromic thin film on ITO glass substrate. Surface morphology, element composition, phase, optical property, and electrochromic characteristics of WO3 film are analyzed. It has been proved that the conversion of precursor films is rapid and efficient, the mean roughness and root mean square of amorphous WO3 thin film are lower than 1.8 nm and 2.2 nm respectively, and the film exhibits good electrochromic performance parameters. The optical modulation range and coloration efficiency of the film can reach 58.5% and 80.2 cm2/C before cycle and 56.3% and 84.0 cm2/C after 100 cycles, coloration time and bleaching time are within 10 s. The method of plasma treatment avoids annealing and prepare WO3 film with good and stable performance. This method has the potential to expand to other electrochromic materials, and provides a new solution for the large area preparation and flexible application of electrochromic materials.

Synergistic enhancement of dual-color electrochromic performance in NiO/CdS quantum dots composite film

NiO is an electrochromic material with extremely strong light modulation capability. However, the defects of the material, such as simple color change and poor cycle stability, limit its application in electrochromic devices and require further improvement and optimization. Nickel-based electrochromic films were firstly prepared by simple hydrothermal method and CdS quantum dots sensitization. The composite electrochromic films adsorbed CdS quantum dots show a multifunctional non-electrochromic film with multiple color changes. It shows up to 54.7% optical modulation range and reversible conversion of two colors. We believe that the electrochromic properties of the composite film are improved due to the synergistic effect of the combination of NiO and CdS in the composite film, which can improve the charge transfer dynamics and light modulation efficiency. Compared with NiO, CdS has a higher carrier density, which increases the charge storage capacity in the composite film, which can improve the color development efficiency and improve the electrochromic reaction. The existence of CdS in the composite film improves the structural stability of NiO. CdS acts as a buffer layer to reduce stress and prevent NiO degradation during repeated coloring and bleaching cycles, improving cycle stability and durability of electrochromic devices. This study provides a reference for the development of NiO polychromatic electrochromic materials and extends the range of non-electrochromic materials from metal oxides to sulfides.

The Progress and Outlook of Multivalent‐Ion‐Based Electrochromism

Electrochromic technology has witnessed numerous achievements in recent years both in research and commercialization. Electrochromic devices (ECD) based on different electrochemical mechanism have been developed for various applications, ranging from smart windows, thermal management, rear views, display, camouflage, etc. Compared to conventional ECDs based on monovalent charge carriers (e.g., H+, Li+), incorporating multivalent ions with rich electrochemistry, high charge density, and small ionic radius has opened new possibilities in novel ECDs. The merits of multivalent ions are harvested in ECDs activated by ion intercalation/deintercalation (e.g., Zn2+, Al3+, Ca2+, Mg2+), reversible metal electrodeposition (e.g., Cu2+, Bi3+, Zn2+), and dynamic metal–ligand interactions (e.g., Cu2+, Fe2+). Herein, the working mechanism, characteristics, and up‐to‐date achievements in multivalent ECDs are summarized and classified accordingly. The applications of multivalent ECDs for smart windows, energy storage, thermal management, multicolor displays, etc., are exemplified. The issues and challenges encountered by multivalent ECDs are emphasized, and the future directions for developing multivalent ECDs are also summarized. The aim of this review is to inspire more efforts in the exploration and the proliferation of multivalent ECDs.

Effect of ZnO dopant on V2O5:ZnO films electrochromic properties

Due to its unique physical and chemical properties, vanadium pentoxide has become a popular material for electrochromic devices, and using doping with other transition metals can enhance its overall performance. Therefore, the peroxovanadate sol-gel method was used to produce ZnO-doped V2O5 thin films. The results of this work show how ZnO doping affected the electrochromic and structural characteristics of thin films of V2O5. The main finding was that adding ZnO to the V2O5 films improved their cyclic stability and reversibility. Besides that, the incorporation of the dopant resulted in a mixture of crystalline phases, according to the X-ray diffraction. The charge density has increased from 28.79 for undoped to 41.68 mC/cm2 for doped films. The UV–Vis transmittance values between bleached and colored states - ΔT at 633 nm - changed from 14.4 to 55.5% for undoped and doped films, respectively. The roughness (root mean square, RMS) of the film remained the same, i.e., 23.5 ± 4.3 for undoped to 23.8 ± 5.1 nm for doped, as revealed by atomic force microscopy. Finally, the doping of V2O5 with ZnO improved the electrochemical and electrochromic characteristics of these new films, making them promising candidates for electrochromic device applications.