Purpurine derivative electrolyte solution with electrochromic characteristic and preparation method and application thereof

Abstract

The invention relates to a viologen derivative electrolyte solution with an electrochromic characteristic and a preparation method and application thereof. The electrolyte solution comprises a viologen derivative and ascorbic acid, the viologen derivative is selected from 1-butyl-4, 4 '-dipyridyl or 1-butyl-1'-(2-propenyl)-4, 4 '-dipyridyl, and the viologen derivative is selected from 1-butyl-4, 4'-dipyridyl or 1-butyl-1 '-( The obtained electrolyte solution can be used for preparing an electrochromic device. Compared with the prior art, the obtained electrochromic device based on the viologen derivative electrolyte can realize color conversion from colorless or brown to purple black under relatively small voltage, and has relatively large light modulation amplitude and relatively high response speed.

Description

Technical Field

[0001] This invention belongs to the field of materials technology and relates to an electrolyte solution of viologen derivative with electrochromic properties, its preparation method and application. Background Technology

[0002] Electrochromic materials are a class of smart materials that can undergo reversible color changes under the influence of an applied electric field, and they have broad application prospects in energy-saving displays, smart windows, anti-glare rearview mirrors, and military camouflage. Among them, viologen derivatives have become one of the most extensively studied electrochromic materials due to their excellent redox properties, obvious color changes, and good chemical stability. Viologen molecules are usually composed of bipyridyl salts, which can be electrochemically reduced to generate free radical cations or neutral states, thereby achieving a reversible color change from colorless (or light-colored) to dark-colored (such as blue or purple). However, traditional viologen materials still have some key problems, such as poor solubility, insufficient cycle stability, and slow response speed, which limit their practical applications.

[0003] In recent years, researchers have attempted to optimize the performance of viologen materials through molecular structure modification (such as introducing different substituents) or composite system design (such as combining with polymers and nanomaterials). For example, the introduction of alkyl chains or aromatic groups can improve the solubility and film-forming properties of viologen; while combining viologen with ionic liquids or gel electrolytes helps to improve ionic conductivity and interfacial stability. However, most viologen derivatives in the present technology are still used in the form of solid electrochromic layers, which require the use of liquid or gel electrolytes. This not only increases the complexity of the device structure, but may also lead to performance degradation due to electrolyte leakage or phase separation.

[0004] Furthermore, traditional electrochromic devices typically employ multilayer structures (such as a transparent conductive layer, an electrochromic layer, an ion storage layer, and an electrolyte layer), resulting in complex and costly fabrication processes. Therefore, developing a single material that combines electrochromic properties and ion conduction capabilities to achieve functional integration of the electrolyte and the electrochromic layer has become an important research direction in this field. Designing a viologen derivative electrolyte material that simultaneously possesses efficient ion transport capabilities and stable electrochromic behavior would significantly simplify device structure, improve response speed, and extend lifespan, possessing significant scientific and application value.

[0005] In summary, existing viologen derivative electrochromic materials still have shortcomings in terms of solubility, stability, and device integration. There is an urgent need to develop novel viologen derivative electrolyte materials to overcome the limitations of traditional multilayer device structures and promote the practical application of electrochromic technology. Summary of the Invention

[0006] The purpose of this invention is to provide an electrolyte solution of viologen derivatives with electrochromic properties, its preparation method, and its applications, to address the shortcomings of existing viologen derivative electrochromic materials in terms of solubility, stability, and device integration. This invention grafts allyl and alkyl groups onto the N-active site of 4,4′-bipyridine, utilizing the allyl and alkyl groups to reduce the overall energy level gap of small organic molecules, thereby effectively solving the problems of long response time and poor cycle stability in viologen derivative electrochromic materials.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A first aspect of the present invention provides an electrolyte solution of a viologen derivative having electrochromic properties, comprising a viologen derivative and ascorbic acid; wherein the viologen derivative is selected from 1-butyl-4,4′-bipyridine or 1-butyl-1′-(2-propenyl)-4,4′-bipyridine.

[0009] In some specific embodiments, the mass ratio of the viologen derivative to ascorbic acid is (2-5):(2-4).

[0010] In some specific embodiments, the concentration of the viologen derivative in the electrolyte solution is 4–10 g / L.

[0011] A second aspect of the present invention provides a method for preparing a viologen derivative electrolyte solution with electrochromic properties as described above, comprising: mixing a viologen derivative with ascorbic acid in water.

[0012] In some specific embodiments, when the viologen derivative is 1-butyl-4,4′-bipyridine, the preparation method of the viologen derivative includes: mixing 1-iodobutane and 4,4′-bipyridine in acetonitrile, refluxing, filtering and collecting the filtrate, and precipitating the filtrate in diethyl ether to obtain 1-butyl-4,4′-bipyridine.

[0013] In some specific embodiments, the mass ratio of 1-iodobutane to 4,4′-bipyridine is 3.5:3 to 1:2;

[0014] The concentration of the 4,4′-bipyridine in acetonitrile is 0.2–0.3 g / mL;

[0015] In the reflux reaction, the reaction temperature is 50–70°C and the reaction time is 20–30 h.

[0016] In some specific embodiments, when the viologen derivative is 1-butyl-1′-(2-propenyl)-4,4′-bipyridine, the preparation method of the viologen derivative includes: mixing 1-butyl-4,4′-bipyridine with 3-chloropropene in acetonitrile, refluxing, taking the precipitate, washing, and drying to obtain the product.

[0017] In some specific embodiments, the mass ratio of 1-butyl-4,4′-bipyridine to 3-chloropropene is 1:(2-3);

[0018] The concentration of 1-butyl-4,4′-bipyridine in acetonitrile is 20–40 g / mL;

[0019] In the reflux reaction, the reaction temperature is 70–90°C and the reaction time is 40–60 h.

[0020] In some specific embodiments, the mixing includes stirring and / or ultrasonic treatment.

[0021] A third aspect of the present invention provides an application of the viologen derivative electrolyte solution with electrochromic properties as described above, including using the viologen derivative electrolyte solution to prepare electrochromic devices, and further using it to prepare smart windows or displays.

[0022] In some specific embodiments, the electrochromic device includes:

[0023] The color-changing device cavity includes an insulating frame and transparent conductive substrates on both sides of the electrode frame; and,

[0024] The electrochromic solution is a viologen derivative electrolyte solution with electrochromic properties as described above, which is filled into the cavity of the color-changing device.

[0025] In some specific embodiments, the insulating frame is 3M double-sided adhesive.

[0026] In some specific embodiments, the transparent conductive substrate is fluorine-doped tin oxide (FTO) conductive glass.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The viologen derivative-based electrolyte obtained in this invention has a small energy level gap, which greatly shortens the response time of electrochromism. This allows the electrochromic device to achieve a rapid color change from colorless or brown to purplish-black at a relatively low voltage. The presence of butyl and propenyl substituents alters the electron cloud density of 4,4′-bipyridine, giving the electrochromic device, which is used as a color-changing electrolyte, a large light modulation amplitude. When applied to practical smart windows, it exhibits significant transmittance changes. Furthermore, its asymmetric structure suppresses the dimerization of viologen molecules, improving the cycling stability of the color-changing device.

[0029] The viologen derivative material of the present invention has high transmittance after being dissolved in a solvent, which ensures the transparency of the device in the fading state and achieves excellent and stable light transmission effect.

[0030] The viologen derivative-based electrolyte obtained by this invention is soluble in both water and organic solvents, thus enriching its application scenarios.

[0031] This invention uses viologen derivatives and ascorbic acid to form an electrolyte solution, thereby merging the electrolyte layer and the electrochromic layer into one layer and assembling an integrated electrochromic device, which greatly simplifies the device assembly process. Attached Figure Description

[0032] Figure 1 The diagram shows the structure of the electrochromic device based on viologen derivative electrolyte prepared according to Examples 1 and 2 of the present invention.

[0033] Figure 2 The response time is the electrochromic device based on viologen derivative electrolyte prepared according to Example 2 of the present invention.

[0034] Figure 3 Scanning electron microscope images of 1-butyl-4,4′-bipyridine (a) and 1-butyl-1′-(2-propenyl)-4,4′-bipyridine (b) prepared according to Examples 1 and 2 of the present invention.

[0035] Figure 4 Fourier transform infrared spectra of 1-butyl-4,4′-bipyridine and 1-butyl-1′-(2-propenyl)-4,4′-bipyridine prepared using Examples 1 and 2 of this invention.

[0036] Figure 5 The images show the effects of the fading state (a) and the colored state (b) of the electrochromic device based on viologen derivative electrolyte prepared according to Example 3 of the present invention.

[0037] Figure 6 The transmittance curves of the colored and faded states of the electrochromic device based on viologen derivative electrolyte prepared according to Example 3 of the present invention are shown.

[0038] Figure 7 The image shows the response time curve of the electrochromic device based on viologen derivative electrolyte prepared according to Example 3 of the present invention.

[0039] Figure 8 The image shows the cycle stability curve of the electrochromic device based on viologen derivative electrolyte prepared according to Example 3 of the present invention.

[0040] Figure 9 The transmittance curves for the colored and faded states of the electrochromic device based on viologen derivative electrolyte prepared using Comparative Example 1 of this invention are shown.

[0041] Figure 10 The image shows the response time curve of the electrochromic device based on viologen derivative electrolyte prepared using Comparative Example 1 of this invention.

[0042] Figure 11 The transmittance curves of the colored and faded states of the electrochromic device based on viologen derivative electrolyte prepared using Comparative Example 2 of the present invention are shown.

[0043] Figure 12 The response time curve of the electrochromic device based on viologen derivative electrolyte prepared using Comparative Example 2 of this invention is shown.

[0044] Explanation of markings in the diagram:

[0045] 1-FTO conductive glass; 2-Double-sided adhesive. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0047] In the following embodiments, unless otherwise specified, the raw materials, reagents or processing techniques are all conventional commercial products or conventional processing techniques in the art.

[0048] Experimental procedures for cycle stability testing: Connect the device to the electrochemical workstation, connect the working electrode to the device's colored electrode, the counter electrode to the counter electrode, and the reference electrode. Set a multi-step constant voltage program, simultaneously start the spectrophotometer, and set the "time-transmittance" monitoring mode. After the test, save the electrochemical data (current-voltage curve) and optical data (transmittance change). Experimental conditions: Set the colored voltage to -1.7V for 5s and 0V for 20s, and set the required number of cycles.

[0049] Based on the reaction ratio of the viologen derivative electrolyte and the reaction temperature, any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of this invention are considered equivalent substitutions and are included within the scope of protection of this invention.

[0050] Example 1

[0051] An electrochromic device based on a 1-butyl-4,4′-bipyridine electrolyte, the preparation method of which includes the following steps:

[0052] (1) First, 3.5 g of 1-iodobutane and 3 g of 4,4′-bipyridine were mixed in 10 mL of acetonitrile and refluxed at 60 °C for 24 h. The resulting product was separated by filtration, precipitated in diethyl ether, and dried to obtain 1-butyl-4,4′-bipyridine.

[0053] (2) Add 0.04g of 1-butyl-4,4′-bipyridine prepared in step (1) to 5mL of aqueous solution containing 0.02g of ascorbic acid, stir at 400 rpm for 10 minutes, and then sonicate at 25Hz and 70W for 10 minutes to obtain an electrolyte with electrochromic properties.

[0054] (3) First, compare the two 2.5×5cm pieces. 2 The FTO conductive glass 1 was subjected to alcohol washing, water washing, and ultrasonication, and then dried to obtain the FTO conductive glass electrode for later use. The prepared FTO conductive glass 1, a 5mm wide and 1mm thick 3M double-sided adhesive 2, and the FTO conductive glass 1 were assembled. Specifically, starting from one short side of the FTO conductive glass 1, the double-sided adhesive 2 (3M double-sided adhesive, forming a frame shape after assembly, with an outer edge length of 4cm and a width of 2.5cm) was applied along the inner edge, forming a 1.5×3cm enclosure. 2 The area was then fitted with another FTO conductive glass 1 along its short side, resulting in a 1.5×3cm area. 2 The cross-sectional area of ​​the cavity is 2.5 × 1 cm. 2 Electrochromic devices made of blank FTO conductive glass, such as Figure 1 As shown;

[0055] (4) The electrolyte with electrochromic properties prepared in step (2) is injected into the cavity of the electrochromic device prepared in step (3) to obtain an electrochromic device containing 1-butyl-4,4′-bipyridine electrolyte.

[0056] Example 2

[0057] An electrochromic device comprising 1-butyl-4,4′-bipyridine and 1-butyl-1′-(2-propenyl)-4,4′-bipyridine electrolytes, the preparation method of which includes the following steps:

[0058] (1) Dissolve 1 g of 1-butyl-4,4′-bipyridine in 25 mL of acetonitrile, add 2 g of 3-chloropropene and reflux at 80 °C for 48 h. The resulting mixture forms a brown precipitate, which is collected, washed with acetonitrile, and dried to obtain 1-butyl-1′-(2-propenyl)-4,4′-bipyridine.

[0059] (2) Add 0.04g of 1-butyl-1′-(2-propenyl)-4,4′-bipyridine prepared in step (1) to 5mL of aqueous solution containing 0.02g of ascorbic acid, stir at 400 rpm for 10 minutes, and then sonicate at 25Hz and 70W for 10 minutes to obtain an electrolyte with electrochromic properties;

[0060] (3) First, compare the two 2.5×5cm pieces. 2 The FTO conductive glass was subjected to alcohol washing, water washing, and ultrasonication, and then dried to obtain an FTO conductive glass electrode for later use. The prepared FTO conductive glass, 5mm wide and 1mm thick 3M double-sided adhesive, and FTO conductive glass were assembled to form an electrode with a diameter of 1.5×3cm. 2 Cavity area and 2.5×1cm 2 Electrochromic devices using blank FTO conductive glass;

[0061] (4) The electrolyte with electrochromic properties prepared in step (2) is injected into the cavity of the electrochromic device prepared in step (3) to obtain an electrochromic device containing 1-butyl-1′-(2-propenyl)-4,4′-bipyridine electrolyte.

[0062] The response time of the electrochromic device containing 1-butyl-1′-(2-propenyl)-4,4′-bipyridine electrolyte prepared in Example 2 is as follows: Figure 2 As shown, the staining time was 5.3 s and the fading time was 13.1 s; scanning electron microscope images of 1-butyl-4,4′-bipyridine and 1-butyl-1′-(2-propenyl)-4,4′-bipyridine prepared in Examples 1 and 2 are shown below. Figure 3 As shown, it has a layered structure; Figure 4 The infrared spectra of the two amethyst derivatives confirm that the synthesized samples are 1-butyl-4,4′-bipyridine and 1-butyl-1′-(2-propenyl)-4,4′-bipyridine, with the following structural formulas:

[0063] 1-Butyl-4,4′-Bipyridine:

[0064]

[0065] 1-Butyl-1′-(2-Propylene)-4,4′-Bipyridine:

[0066]

[0067] Example 3

[0068] An electrochromic device based on a 1-butyl-4,4′-bipyridine electrolyte, the preparation method of which includes the following steps:

[0069] (1) First, 1 g of 1-iodobutane and 2 g of 4,4′-bipyridine were mixed in 10 mL of acetonitrile and refluxed at 60 °C for 24 h. The resulting product was separated by filtration, precipitated in diethyl ether, and dried to obtain 1-butyl-4,4′-bipyridine;

[0070] (2) Add 0.04g of 1-butyl-4,4′-bipyridine prepared in step (1) to 5mL of aqueous solution containing 0.02g of ascorbic acid, stir at 400 rpm for 10 minutes, and then sonicate at 25Hz and 70W for 10 minutes to obtain an electrolyte with electrochromic properties.

[0071] (3) First, compare the two 2.5×5cm pieces. 2 The FTO conductive glass was subjected to alcohol washing, water washing, and ultrasonication, and then dried to obtain an FTO conductive glass electrode for later use. The prepared FTO conductive glass, 5mm wide and 1mm thick 3M double-sided adhesive, and FTO conductive glass were assembled to form an electrode with a diameter of 1.5×3cm. 2 Cavity area and 2.5×1cm 2 Electrochromic devices using blank FTO conductive glass;

[0072] (4) The electrolyte with electrochromic properties prepared in step (2) is injected into the cavity of the electrochromic device to obtain an electrochromic device containing 1-butyl-4,4′-bipyridine electrolyte.

[0073] When a voltage of ±1.4 to 1.7V is applied between the two sides of the FTO conductive glass in the electrochromic device prepared in this embodiment, it rapidly turns purplish-black; when a voltage of 0V is applied, the device changes from purple to colorless. Figure 5 Images of the faded and colored states of the electrochromic device containing 1-butyl-4,4′-bipyridine electrolyte prepared in this embodiment.

[0074] The electrochromic device containing 1-butyl-4,4′-bipyridine electrolyte obtained in this embodiment was tested using an electrochemical workstation and a UV-Vis-NIR spectrometer. Coloring and fading were performed at voltages of -1.7V and 0V, and the coloring and fading transmittance curves are shown below. Figure 6 As shown, the light modulation amplitude was tested in the wavelength range of 400–1000 nm using a UV-Vis-NIR spectrophotometer, and the amplitude reached its maximum at a wavelength of 605 nm, which was 67.8%.

[0075] Figure 7 The response time curve shows that when a voltage of ±1.4 to 1.7V is applied, the device rapidly turns purplish-black; when a voltage of 0V is applied, the device changes from purple to colorless. The coloring time of the device is 5.3s, and the fading time is 10.6s.

[0076] Figure 8 The figure shows the cyclic stability curve, indicating that the device can operate stably for up to 70,000 seconds.

[0077] Comparative Example 1

[0078] An electrochromic device based on a 4,4′-bipyridine electrolyte is prepared in a manner that differs from that in Example 3 only in that:

[0079] In step (2), equimolar amounts of 1-(2-propenyl)-4,4′-bipyridine are used instead of 1-butyl-4,4′-bipyridine;

[0080] The rest is the same as in Example 1.

[0081] Figure 9 As shown, the light modulation amplitude was tested in the wavelength range of 400–1000 nm using a UV-Vis-NIR spectrophotometer, and the amplitude reached its maximum of 56.9% at a wavelength of 605 nm.

[0082] Figure 10 The response time curve shows that when a voltage of ±1.4 to 1.7V is applied, the device rapidly turns purplish-black; when a voltage of 0V is applied, the device changes from purple to colorless. The coloring time of the device is 7.1s, and the fading time is 17.8s.

[0083] Comparative Example 2

[0084] An electrochromic device based on a 1-butyl-4,4′-bipyridine electrolyte, the preparation method of which differs from that in Example 1 only in that:

[0085] 0.02g of borax was used instead of 0.02g of ascorbic acid;

[0086] The rest is the same as in Example 1.

[0087] Figure 11 As shown, the light modulation amplitude was tested in the wavelength range of 400–1000 nm using a UV-Vis-NIR spectrophotometer, and reached its maximum at a wavelength of 605 nm, which was 64.5%.

[0088] Figure 12The response time curve shows that when a voltage of ±1.4 to 1.7V is applied, the device rapidly turns purplish-black; when a voltage of 0V is applied, the device changes from purplish-black to colorless. The coloring time of the device is 7.4s, and the fading time is 15.5s.

[0089] Example 4

[0090] An electrochromic device based on a 1-butyl-4,4′-bipyridine electrolyte, the preparation method of which includes the following steps:

[0091] (1) Dissolve 0.5g of 1-butyl-4,4′-bipyridine in 25mL of acetonitrile, add 1.5g of 3-bromopropene and reflux at 80℃ for 48h. The resulting mixture forms a brown precipitate, which is collected, washed with acetonitrile, and dried to obtain 1-butyl-1′-(2-propenyl)-4,4′-bipyridine.

[0092] (2) Add 0.04g of 1-butyl-1′-(2-propenyl)-4,4′-bipyridine prepared in step (1) to 5mL of aqueous solution containing 0.02g of ascorbic acid, stir at 400 rpm for 10 minutes, and then sonicate at 25Hz and 70W for 10 minutes to obtain an electrolyte with electrochromic properties;

[0093] (3) First, compare the two 2.5×5cm pieces. 2 The FTO conductive glass was subjected to alcohol washing, water washing, and ultrasonication, and then dried to obtain an FTO conductive glass electrode for later use. The prepared FTO conductive glass, 5mm wide and 1mm thick 3M double-sided adhesive, and FTO conductive glass were assembled to form an electrode with a diameter of 1.5×3cm. 2 Cavity area and 2.5×1cm 2 Electrochromic devices using blank FTO conductive glass;

[0094] (4) The electrolyte with electrochromic properties prepared in step (2) is injected into the cavity of the electrochromic device prepared in step (3) to obtain an electrochromic device containing 1-butyl-1′-(2-propenyl)-4,4′-bipyridine electrolyte.

[0095] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A viologen derivative electrolyte solution with electrochromic properties, characterized in that, It includes viologen derivatives and ascorbic acid; the viologen derivatives are selected from 1-butyl-4,4′-bipyridine or 1-butyl-1′-(2-propenyl)-4,4′-bipyridine.

2. The viologen derivative electrolyte solution with electrochromic properties according to claim 1, characterized in that, The mass ratio of the viologen derivative to ascorbic acid is (2-5):(2-4).

3. The viologen derivative electrolyte solution with electrochromic properties according to claim 1, characterized in that, The concentration of the viologen derivative in the electrolyte solution is 4–10 g / L.

4. A method for preparing a viologen derivative electrolyte solution with electrochromic properties as described in any one of claims 1 to 3, characterized in that, The method includes: mixing viologen derivatives with ascorbic acid in water.

5. The method for preparing the viologen derivative electrolyte solution with electrochromic properties according to claim 4, characterized in that, When the viologen derivative is 1-butyl-4,4′-bipyridine, the preparation method of the viologen derivative includes: mixing 1-iodobutane and 4,4′-bipyridine in acetonitrile, refluxing, filtering and collecting the filtrate, precipitating the filtrate in diethyl ether to obtain 1-butyl-4,4′-bipyridine.

6. The method for preparing the viologen derivative electrolyte solution with electrochromic properties according to claim 5, characterized in that, The mass ratio of 1-iodobutane to 4,4′-bipyridine is 3.5:3 to 1:2; The concentration of the 4,4′-bipyridine in acetonitrile is 0.2–0.3 g / mL; In the reflux reaction, the reaction temperature is 50–70°C and the reaction time is 20–30 h.

7. The method for preparing the viologen derivative electrolyte solution with electrochromic properties according to claim 4, characterized in that, When the viologen derivative is 1-butyl-1′-(2-propenyl)-4,4′-bipyridine, the preparation method of the viologen derivative includes: mixing 1-butyl-4,4′-bipyridine with 3-chloropropene in acetonitrile, refluxing, taking the precipitate, washing, and drying to obtain the product.

8. The method for preparing the viologen derivative electrolyte solution with electrochromic properties according to claim 7, characterized in that, The mass ratio of 1-butyl-4,4′-bipyridine to 3-chloropropene is 1:(2-3); The concentration of 1-butyl-4,4′-bipyridine in acetonitrile is 20–40 g / mL; In the reflux reaction, the reaction temperature is 70–90°C and the reaction time is 40–60 h. In some specific embodiments, the mixing includes stirring and / or ultrasonic treatment.

9. The application of a viologen derivative electrolyte solution with electrochromic properties as described in any one of claims 1 to 3, characterized in that, The viologen derivative electrolyte solution is used to prepare electrochromic devices, and further used to prepare smart windows or displays.

10. The application of the viologen derivative electrolyte solution with electrochromic properties according to claim 9, characterized in that, The electrochromic device includes: The color-changing device cavity includes an insulating frame and transparent conductive substrates on both sides of the insulating frame; and, The electrochromic solution is a viologen derivative electrolyte solution with electrochromic properties as described in any one of claims 1 to 3, which is filled into the cavity of the color-changing device.

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