An electrochromic solution containing polycarboxylic acid and an electrochromic device prepared therefrom

Abstract

The present invention provides an electrochromic solution containing polycarboxylic acid and an electrochromic device prepared therefrom; the electrochromic solution comprises the following components in concentrations: 5-15 mmol / L of a viologen compound, 5-15 mmol / L of an electroactive material for an electrode, 5-15 mmol / L of a lithium salt, and 20-60 mmol / L of a polycarboxylic acid. In the electrochromic solution of the present invention, carboxyl anions can effectively generate electrostatic attraction with quaternary ammonium nitrogen atom cations in viologen molecules, thereby reducing the π-π stacking effect between the viologen molecules, reducing the contact probability of the two molecules, thereby effectively inhibiting the generation of free radical dimers, improving the stability of the electrochromic device, and increasing the number of cycles.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochromic change, and in particular relates to an electrochromic solution containing polycarboxylic acid and an electrochromic device prepared therefrom. Background Art

[0002] Electrochromism refers to the phenomenon that the optical properties of a material undergo a stable and reversible color change under the action of an external electric field, which is manifested in the reversible change of color and transparency. Materials with electrochromic properties are called electrochromic materials, and devices made of electrochromic materials are called electrochromic devices.

[0003] Electrochromic materials are divided into inorganic electrochromic materials and organic electrochromic materials. The typical representative of inorganic electrochromic materials is tungsten trioxide. At present, electrochromic devices with WO3 as functional material have been industrialized. Organic electrochromic materials mainly include polythiophene and its derivatives, viologen, tetrathiafulvalene, metal phthalocyanine compounds, etc. Electrochromic materials with viologen as functional material have been put into practical application.

[0004] Viologen compounds are one of the most widely used electrochromic materials due to their advantages such as easy availability of raw materials and rich color variations. However, the cationic radicals in the core color-changing substances of viologen molecules are prone to form free radical dimers during the operation of the device, resulting in a decrease in the stability of the viologen electrochromic device. Therefore, improving the cycle performance of the viologen electrochromic device is a problem that needs to be solved. Summary of the invention

[0005] Based on this, the object of the present invention is to provide an electrochromic solution containing polycarboxylic acid and an electrochromic device prepared therefrom. The electrochromic solution can effectively reduce the π-π stacking effect between viologen molecules, inhibit the generation of free radical dimers, and improve the viologen-based electrochromic device.

[0006] To achieve the above object, the present invention adopts the following technical solution.

[0007] An electrochromic solution comprises the following components in concentrations: 5-15 mmol / L of a viologen compound, 5-15 mmol / L of an electroactive material for a counter electrode, 5-15 mmol / L of a lithium salt, and 20-60 mmol / L of a polycarboxylic acid.

[0008] In some preferred embodiments, the electrochromic solution comprises components in the following concentrations: 7-12 mmol / L of viologen compound, 7-12 mmol / L of counter electrode electroactive material, 7-12 mmol / L of lithium salt, and 30-50 mmol / L of polycarboxylic acid.

[0009] More preferably, the electrochromic solution comprises components in the following concentrations: 9-11 mmol / L of viologen compound, 9-11 mmol / L of counter electrode electroactive material, 9-11 mmol / L of lithium salt, and 35-45 mmol / L of polycarboxylic acid.

[0010] In some embodiments, the viologen compound is selected from at least one of the following compounds: ethyl viologen hexafluorophosphate, methyl viologen hexafluorophosphate, heptyl viologen hexafluorophosphate, p-trifluoromethylphenyl viologen hexafluorophosphate, and phenyl viologen hexafluorophosphate.

[0011] In some embodiments, the polycarboxylic acid is selected from at least one of 1,2-cyclohexanediaminetetraacetic acid, 1,2-propylenediamine-N,N,N',N'-tetraacetic acid, and N,N,N',N'-1,4-phenylenediaminetetraacetic acid.

[0012] In some embodiments, the counter electrode electroactive material is selected from at least one of ferrocene and benzoquinone small molecule compounds.

[0013] In some embodiments, the lithium salt is selected from at least one of lithium bis(trifluoromethylsulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate.

[0014] In some embodiments, the solvent of the electrochromic solution is selected from at least one of propylene carbonate, butyrolactone, 2-acetylbutyrolactone, γ-valerolactone, ethylene carbonate, cyclopentane sulfone, 3-methylcyclopentane sulfone, dimethylacetamide, dimethylformamide, acetonitrile, glutaronitrile, 2-methylglutaronitrile, 3-hydroxypropionitrile, tetraethylene glycol dimethyl ether, dimethyl sulfoxide, ethoxyethanol and cyclopentanone.

[0015] The present invention also provides the use of the electrochromic solution described above in preparing an electrochromic device.

[0016] The present invention also provides an electrochromic device, wherein the raw materials for preparing the electrochromic device include the electrochromic solution described above.

[0017] In some embodiments, the electrochromic device comprises a first FTO conductive glass and a second FTO conductive glass, wherein a sealed chamber is formed between the first FTO conductive glass and the second FTO conductive glass by glue sealing, and the sealed chamber is filled with the electrochromic solution as described above.

[0018] The present invention obtains an electrochromic solution through optimization, and the electrochromic solution comprises components such as a viologen compound and a polycarboxylic acid. Under the system of the present invention, the carboxyl anions can effectively generate electrostatic attraction with the quaternary ammonium nitrogen atom positive ions in the viologen molecules, thereby reducing the π-π stacking effect between the viologen molecules, reducing the contact probability of the two molecules, thereby effectively inhibiting the generation of free radical dimers, improving the stability of the electrochromic device, and increasing the number of cycles. DETAILED DESCRIPTION

[0019] The experimental methods in the following examples of the present invention, where no specific conditions are specified, are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0020] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0021] The terms "including" and "having" and any variations thereof of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, device, product or equipment comprising a series of steps is not limited to the listed steps or modules, but may optionally include steps not listed, or may optionally include other steps inherent to these processes, methods, products or equipment.

[0022] In the present invention, the term "multiple" refers to two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0023] Taking polycarboxylic acid as an example, the principle of polycarboxylic acid anions blocking the free viologen cations in the electrochromic solution of the present invention is as follows:

[0024]

[0025] The following describes the invention in conjunction with specific embodiments.

[0026] Example 1

[0027] This embodiment provides an electrochromic solution, the composition of which is as follows: 0.1 mmol ethyl viologen hexafluorophosphate, 0.1 mmol ferrocene, 0.1 mmol lithium bis(trifluoromethylsulfonyl)imide, 10 ml allyl carbonate, and 0.4 mmol 1,2-cyclohexanediaminetetraacetic acid.

[0028] Example 2

[0029] This embodiment provides an electrochromic solution, which has the following composition: 0.15 mmol heptyl viologen hexafluorophosphate, 0.15 mmol ferrocene, 0.15 mmol lithium bis(trifluoromethylsulfonyl)imide, 10 ml γ-valerolactone, and 0.6 mmol 1,2-cyclohexanediaminetetraacetic acid.

[0030] Example 3

[0031] This embodiment provides an electrochromic solution, which has the following composition: 0.12 mmol of p-trifluoromethylphenyl viologen hexafluorophosphate,

[0032] 0.12mmol ferrocene, 0.12mmol lithium bis(trifluoromethylsulfonyl)imide, 10ml ethylene carbonate, 0.5mmol 1,2-cyclohexanediaminetetraacetic acid.

[0033] Comparative Example 1

[0034] This comparative example provides an electrochromic solution, which, except that it does not contain 1,2-cyclohexanediaminetetraacetic acid, has the same components as Example 1, specifically as follows: 0.1 mmol ethyl viologen hexafluorophosphate, 0.1 mmol ferrocene, 0.1 mmol lithium bis(trifluoromethylsulfonyl)imide, and 10 ml allyl carbonate.

[0035] The electrochromic devices are prepared using the electrochromic solutions in the above embodiments and comparative examples, respectively, and specifically include the following steps: taking a first FTO conductive glass and a second FTO conductive glass, and forming a sealed chamber between the first FTO conductive glass and the second FTO conductive glass by glue sealing, leaving a small opening, and then filling the sealed chamber with the electrochromic solutions in embodiments 1 to 3 and comparative example 1, respectively, and then sealing with ultraviolet glue to obtain the corresponding electrochromic device.

[0036] The stability of the prepared electrochromic device was tested, and the testing method was as follows:

[0037] The electrochromic device was subjected to a cyclic voltage of 1.5V-0V (coloring voltage 10s, fading voltage 10s) using an electrochemical workstation. The device was tested under a UV spectrophotometer. The attenuation of the optical contrast of the device after several cycles was tested. The number of cycles was counted until the attenuation exceeded >20%.

[0038] The test results are shown in Table 1 below:

[0039] Table 1

[0040] Group Initial optical contrast Cycle times Example 1 74.2％ 4280 Example 2 75.4％ 4498 Example 3 70.3％ 2125 Comparative Example 1 74.1％ 564

[0041] The above results show that the electrochromic device prepared by the electrochromic solution of the present invention (Examples 1 to 3) has good stability; however, since the electrochromic solution of Comparative Example 1 does not contain a polycarboxylic acid component, the cationic radicals in the core color-changing substance of the viologen molecule are easily formed into free radical dimers during the operation of the device, which reduces the stability of the prepared electrochromic device.

[0042] In summary, in the electrochromic solution of the present invention, the carboxyl anions can effectively generate electrostatic attraction with the quaternary ammonium nitrogen atom cations in the viologen molecules, thereby reducing the π-π stacking effect between the viologen molecules, reducing the contact probability between the two molecules, thereby effectively inhibiting the formation of free radical dimers, improving the stability of the electrochromic device, and increasing the number of cycles.

[0043] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An electrochromic solution, characterized in that: The electrochromic solution comprises components in the following concentrations: 5-15 mmol / L of a viologen compound, 5-15 mmol / L of an electroactive material for a counter electrode, 5-15 mmol / L of a lithium salt, and 20-60 mmol / L of a polycarboxylic acid, wherein the viologen compound is selected from at least one of the following compounds: ethyl viologen hexafluorophosphate, methyl viologen hexafluorophosphate, heptyl viologen hexafluorophosphate, p-trifluoromethylphenyl viologen hexafluorophosphate, and phenyl viologen hexafluorophosphate; and the polycarboxylic acid is selected from at least one of 1,2-cyclohexanediaminetetraacetic acid, 1,2-propylenediamine-N,N,N',N'-tetraacetic acid, and N,N,N',N'-1,4-phenylenediaminetetraacetic acid.

2. The electrochromic solution according to claim 1, characterized in that The electrochromic solution comprises the following components in concentrations: 7-12 mmol / L of a viologen compound, 7-12 mmol / L of an electroactive material for a counter electrode, 7-12 mmol / L of a lithium salt, and 30-50 mmol / L of a polycarboxylic acid.

3. The electrochromic solution according to claim 1, characterized in that The electrochromic solution comprises the following components in concentrations: 9-11 mmol / L of a viologen compound, 9-11 mmol / L of an electroactive material for a counter electrode, 9-11 mmol / L of a lithium salt, and 35-45 mmol / L of a polycarboxylic acid.

4. The electrochromic solution according to claim 1, characterized in that The counter electrode electroactive material is selected from at least one of ferrocene and benzoquinone small molecule compounds; and / or, the lithium salt is selected from at least one of lithium bis(trifluoromethylsulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate.

5. The electrochromic solution according to claim 1, characterized in that The solvent of the electrochromic solution is selected from at least one of propylene carbonate, butyrolactone, 2-acetylbutyrolactone, γ-valerolactone, ethylene carbonate, cyclopentane sulfone, 3-methylcyclopentane sulfone, dimethylacetamide, dimethylformamide, acetonitrile, glutaronitrile, 2-methylglutaronitrile, 3-hydroxypropionitrile, tetraethylene glycol dimethyl ether, dimethyl sulfoxide, ethoxyethanol and cyclopentanone.

6. Use of the electrochromic solution according to any one of claims 1 to 5 in the preparation of an electrochromic device.

7. An electrochromic device, characterized in that: The raw material for preparing the electrochromic device comprises the electrochromic solution according to any one of claims 1 to 5.

8. The electrochromic device according to claim 7, characterized in that: The electrochromic device comprises a first FTO conductive glass and a second FTO conductive glass, wherein a sealed chamber is formed between the first FTO conductive glass and the second FTO conductive glass by glue sealing, and the sealed chamber is filled with the electrochromic solution according to any one of claims 1 to 5.

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