Polyaniline and viologen compounded electrochromic device as well as preparation method and application thereof
By using a composite electrochromic device of polyaniline and viologen, combining viologen and redox mediator, the problems of limited color and insufficient stability of existing electrochromic materials are solved, achieving multi-tone and stable electrochromic effects.
Patent Information
- Application Number
- CN202511878858.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-01-16
AI Technical Summary
Existing electrochromic materials such as polyaniline and viologen have problems such as limited color richness, poor chemical stability, short cycle life and large voltage variation range when used alone, resulting in poor device performance.
A composite electrochromic device using polyaniline and viologen is developed. By adding viologen and a redox mediator to the electrolyte gel and combining them with an indium tin oxide glass electrode, the working electrode and counter electrode are formed, thereby achieving rich color changes and improving cycle stability of the device.
It achieves multi-tone color-changing effects within a small voltage variation range, improves the device's cycle stability and color richness, reduces the color-changing voltage, and extends the device's lifespan.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of electrochromic device technology, and more particularly to an electrochromic device composed of polyaniline and viologen, its preparation method, and its application. Background Technology
[0002] Electrochromism refers to the phenomenon where a material undergoes a stable and reversible change in color or optical properties (such as transmittance and absorbance) through a reversible electrochemical oxidation-reduction reaction under the influence of an applied electric field. Electrochromic devices fabricated based on this technology have broad application prospects in fields such as smart windows, anti-glare rearview mirrors, information displays, energy-efficient buildings, and adaptive camouflage. A typical electrochromic device usually consists of a transparent conductive layer, an electrochromic layer, an ion-conducting layer (electrolyte), and an ion storage layer (counter electrode).
[0003] Polyaniline (PANI) has become a promising electrochromic material due to its low cost, simple synthesis, good environmental stability, and unique multiple redox states. PANI exhibits three basic states under different applied voltages: fully reduced (pale yellow); intermediate oxidized (green); and fully oxidized (dark blue / purple). Although PANI displays a color range from yellow to green to blue, its color richness is limited, making it difficult to cover key colors such as purple, red, and transparency. Furthermore, PANI exhibits poor chemical stability in its deeply oxidized state, making it prone to irreversible degradation and shortening the cycle life of devices. Additionally, there is still room for improvement in its coloring efficiency, response speed, and optical contrast.
[0004] Violet (1,1'-disubstituted-4,4'-bipyridinium salt) is another important class of organic electrochromic materials. Its electrochromic mechanism is mainly based on two reversible single-electron reduction reactions: the divalent cation state (V²⁺), i.e., the oxidized state, is usually colorless or light-colored; the monocation radical state (V•⁺), i.e., the one-electron reduced state, exhibits a strong color, usually deep purple or blue, the specific color depending on the nature of the substituents on its nitrogen atom; and the completely neutral state (V... 0 (This refers to further reduction), and the color usually differs from the free ground state, potentially being yellow, red, or colorless. The advantages of viologen compounds are high coloring efficiency, fast response speed, and the ability to adjust the color through chemical modification of the molecular structure.
[0005] To overcome the limitations of single materials, researchers have attempted to composite or blend different electrochromic materials. For example, they have copolymerized two or more conductive polymers of different colors, or stacked different electrochromic layers in the same device. However, these methods often suffer from problems such as complex processes, prominent interface issues, difficulties in potential matching between layers, and high costs.
[0006] Therefore, it is of great significance to research and develop a novel composite electrochromic device to solve the above problems. Summary of the Invention
[0007] In view of this, the technical problem to be solved by the present invention is to provide an electrochromic device composed of polyaniline and viologen, its preparation method, and its application. The electrochromic device exhibits high cycle stability and can display a richer range of colors.
[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0009] This invention provides an electrochromic device composed of polyaniline and viologen, comprising a working electrode, an electrolyte gel, and a counter electrode;
[0010] The electrochromic layer of the working electrode is a polyaniline film;
[0011] The electrolyte gel contains viologen.
[0012] This invention, through the combined action of polyaniline and viologen, not only enables the electrochromic device to achieve rich color changes, but also significantly improves the device's cycle stability.
[0013] Preferably, the concentration of viologen in the electrolyte gel is 0.0025~0.01 mol / L; more preferably, it is 0.0050~0.01 mol / L; and even more preferably, it is 0.0050~0.0075 mol / L.
[0014] This invention achieves color modulation of the electrochromic device by combining a suitable type of viologen with polyaniline.
[0015] Preferably, the violet is selected from one or more of benzyl violet, phenyl violet, and heptyl violet; more preferably, it is benzyl violet or phenyl violet.
[0016] The electrolyte gel of the electrochromic device described in this invention also contains a highly efficient and reversible redox mediator, which promotes charge transport and inhibits viologen side reactions, thereby improving the overall electrochemical performance of the device.
[0017] The redox mediators include, but are not limited to, ferrocene and its derivatives (such as ferrocene methanol), other metallocenes (cobaltocene), metal phthalocyanine / porphyrin complexes, ferricyanide / ferrocyanide, polyoxometalates, etc.
[0018] Preferably, the electrolyte gel further comprises ferrocene or ferrocene methanol; more preferably, ferrocene.
[0019] Preferably, the solvent of the electrolyte gel is selected from one or more of propylene carbonate, acetone, chloroform, and butanone; more preferably, it is propylene carbonate or acetone.
[0020] Preferably, the counter electrode is selected from indium tin oxide glass electrode.
[0021] The present invention also provides a method for preparing the above-mentioned electrochromic device composed of polyaniline and viologen, comprising the following steps:
[0022] (1) A uniform polyaniline film is prepared on the surface of an indium tin oxide glass electrode to obtain a working electrode;
[0023] (2) Preparation of an electrolyte gel containing viologen;
[0024] (3) Coat the electrolyte gel obtained in step (2) onto the surface of the working electrode obtained in step (1), and then assemble the counter electrode and the working electrode to obtain the electrochromic device.
[0025] Preferably, the thickness of the polyaniline film is 0.5~1 μm; more preferably 0.8~1 μm; and even more preferably 1 μm.
[0026] Preferably, the polyaniline film is prepared by spraying a polyaniline solution;
[0027] Preferably, the concentration of the polyaniline solution is 0.025wt%~2wt%; more preferably 0.3wt%~1.2wt%; and even more preferably 0.5wt%~0.8wt%.
[0028] The present invention also provides the application of the above-mentioned polyaniline and viologen composite electrochromic device in adaptive camouflage of natural colors.
[0029] Compared with existing technologies, the polyaniline and viologen composite electrochromic device provided by this invention exhibits a greater color contrast at a voltage of -1.5V to 1.5V compared to electroluminescent devices containing only polyaniline. Furthermore, in the electrochromic device described in this invention, the interaction between viologen and polyaniline narrows the voltage range for polyaniline color change, reduces the color-changing voltage, and thus improves the device's cycle stability. In addition, different types of viologen can have different modulation effects on the color display of the electrochromic device. Attached Figure Description
[0030] Figure 1 The cyclic voltammetry curves of the polyaniline and viologen composite electrochromic device prepared in Example 1 are shown in the range of -1.5V to 1.5V.
[0031] Figure 2The cyclic voltammetry curve of the polyaniline and viologen composite electrochromic device prepared in Example 2 after 60 cycles is shown in the range of -1.5V to 1.5V.
[0032] Figure 3 The cyclic voltammetry curves of the electrochromic device prepared in Comparative Example 1 are shown in the range of -1.5V to 1.5V.
[0033] Figure 4 The cyclic voltammetry curves of the electrochromic device prepared in Comparative Example 1 are shown in the range of -2V to 2V. Detailed Implementation
[0034] To further illustrate the present invention, the following detailed description of the polyaniline and viologen composite electrochromic device, its preparation method, and its application are provided in conjunction with embodiments.
[0035] Example 1
[0036] A uniform polyaniline film (1 μm thick) was prepared on the surface of an ITO glass electrode using a spray coating method to serve as the working electrode (the polyaniline film was prepared by spray coating with a polyaniline solution at a concentration of 0.5 wt%). 0.6 g of PVDF (polyvinylidene fluoride) was added to 5 mL of propylene carbonate and heated and stirred until completely transparent. 0.3 g of tetrabutylammonium perchlorate, 0.03 g of benzyl viologen, and 0.02 g of ferrocene were added to the solution to prepare a BV (benzyl viologen) electrolyte. The BV electrolyte was a gel electrolyte with a benzyl viologen concentration of 0.0075 mol / L. The electrolyte was uniformly coated onto the working electrode, and then the ITO glass electrode was placed on top. The entire device was sealed and fixed to obtain a polyaniline and viologen composite electrochromic device.
[0037] The device was tested using cyclic voltammetry.
[0038] When the voltage scanning range is set to -1.5V to 1.5V, the cyclic voltammetry curve is as follows: Figure 1 As shown, the results indicate that the polyaniline and viologen composite electrochromic device prepared in Example 1 exhibits three pairs of symmetrical redox peaks, representing three reversible color changes. Observations show that the device can achieve yellow-green, green, and cyan color changes. Specifically, the color changes are from green to yellow at approximately -0.5V, from light green to dark green at approximately 0.75V, and from green to cyan at approximately 1.25V. Furthermore, within this voltage range, the device exhibits minimal stability degradation after 60 cycles.
[0039] Example 2
[0040] A uniform polyaniline film (1 μm thick) was prepared on the surface of an ITO glass electrode using a spray coating method to serve as the working electrode (the polyaniline film was prepared by spray coating with a polyaniline solution at a concentration of 0.8 wt%). 0.6 g of PVDF was added to 5 mL of propylene carbonate and heated and stirred until completely transparent. 0.3 g of tetrabutylammonium perchlorate, 0.04 g of benzyl viologen, and 0.02 g of ferrocene were added to the solution to prepare a BV electrolyte, which was a gel electrolyte with a benzyl viologen concentration of 0.0050 mol / L. The electrolyte was uniformly coated onto the working electrode, and then the ITO glass electrode was placed on top. The electrode was then sealed and fixed to obtain an electrochromic device composed of polyaniline and viologen.
[0041] The device was tested using cyclic voltammetry.
[0042] When the voltage scanning range is set to -1.5V to 1.5V, it is observed that the device can achieve color changes of yellow-green, green, and cyan. Specifically, the color changes are as follows: around -0.5V, it changes from yellow-green to green; around 0.75V, it changes from light green to dark green; and around 1.25V, it changes from green to cyan. Compared to Example 1, its cyan is lighter (more greenish).
[0043] When the voltage scanning range is set to -1.5V to 1.5V, the cyclic volt-ampere curve of the device is as follows: Figure 2 As shown, the results indicate that the peak value of the polyaniline and viologen composite electrochromic device prepared in Example 2 changed little after 60 cycles. Figure 2 It contains 60 cycles.
[0044] Example 3
[0045] A uniform polyaniline film (1 μm thick) was prepared on the surface of an ITO glass electrode using a spray coating method to serve as the working electrode (the polyaniline film was prepared by spray coating with a polyaniline solution at a concentration of 0.8 wt%). 0.6 g of PVDF was added to 5 mL of propylene carbonate and heated and stirred until completely transparent. 0.3 g of tetrabutylammonium perchlorate, 0.07 g of phenyl viologen, and 0.02 g of ferrocene were added to the solution to prepare a PV (phenyl viologen) electrolyte. The PV electrolyte was a gel electrolyte with a phenyl viologen concentration of 0.0075 mol / L. The electrolyte was uniformly coated onto the working electrode, and then the ITO glass electrode was placed on top. The entire device was sealed and fixed to obtain a polyaniline and viologen composite electrochromic device.
[0046] The device was tested using the cyclic voltammetry method. When the voltage scan range was set to -1V to 1V, the device was able to achieve a color change from yellowish-green to dark green. Although no additional colors appeared, it expanded the range of shades of green. Furthermore, its low color-changing voltage is more conducive to the cyclic stability of the device.
[0047] Comparative Example 1
[0048] A uniform polyaniline film (1 μm thick) was prepared on the surface of an ITO glass electrode using a spray coating method to serve as the working electrode (the polyaniline film was prepared by spray coating with a polyaniline solution at a concentration of 0.5 wt%). 0.6 g of PVDF was added to 5 mL of propylene carbonate and heated and stirred until completely transparent. 0.3 g of tetrabutylammonium perchlorate and 0.02 g of ferrocene were added to the solution to prepare an electrolyte. The electrolyte was uniformly coated onto the working electrode, and then the ITO glass electrode was placed on top. The entire device was sealed to obtain an electrochromic device.
[0049] The device was tested using the cyclic voltammetry method. When the voltage scan range was set to -1.5V to 1.5V, the cyclic voltammetry curve was as follows: Figure 3 As shown, the results indicate that there is no obvious symmetrical redox peak in Comparative Example 1, which means that no reversible redox cycle occurs, that is, only the polyaniline electroluminescent device does not show obvious color change.
[0050] To further explore the color-changing behavior of the polyaniline-only electrochromic device, the applied voltage was increased. When the voltage was set to scan within the range of -2V to 2V, the results were as follows. Figure 4 As shown, the cyclic voltammetry curves show an intersection point, indicating the formation of irreversible products that will further affect the cyclic stability of the device. Observation revealed that the color change of the device was small, even difficult to observe clearly.
[0051] When the applied voltage is increased further and the voltage scanning range is set to -3V to 3V, the polyaniline color-changing layer can change from yellow to dark green, but the cycle symmetry is poor and the color-changing process is not stable.
[0052] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. A polyaniline and viologen complexed electrochromic device, characterized by, comprising a working electrode, an electrolyte gel, a counter electrode; the electrochromic layer of the working electrode is a polyaniline film; the electrolyte gel contains a viologen.
2. The polyaniline and viologen complexed electrochromic device of claim 1, wherein, the concentration of the viologen in the electrolyte gel is 0.0025-0.01 mol / L.
3. The polyaniline and viologen complexed electrochromic device of claim 2, wherein, the viologen is selected from one or more of benzyl viologen, phenyl viologen, and heptyl viologen.
4. The polyaniline and viologen complexed electrochromic device according to any one of claims 1 to 3, characterized in that, the electrolyte gel further comprises ferrocene or ferrocene methanol.
5. The polyaniline and viologen complexed electrochromic device of claim 4, wherein, the solvent of the electrolyte gel is selected from one or more of propylene carbonate, acetone, chloroform, and butanone.
6. The polyaniline and viologen complexed electrochromic device of claim 1, wherein, the counter electrode is selected from an indium tin oxide glass electrode.
7. A method for producing the polyaniline and viologen complexed electrochromic device according to any one of claims 1 to 6, characterized by, comprising the following steps: (1) preparing a uniform polyaniline film on the surface of an indium tin oxide glass electrode to obtain a working electrode; (2) preparing an electrolyte gel containing a viologen; (3) coating the electrolyte gel obtained in step (2) on the surface of the working electrode obtained in step (1), then assembling the counter electrode with the working electrode to obtain the electrochromic device.
8. The preparation method according to claim 7, characterized in that, the thickness of the polyaniline film is 0.5-1 μm.
9. The preparation method according to claim 8, characterized in that, the polyaniline film is prepared by spraying a polyaniline solution; the concentration of the polyaniline solution is 0.025wt%-2wt%.
10. Use of the polyaniline and viologen composite electrochromic device of any one of claims 1-6 in natural color adaptive camouflage.