Electrochromic compound capable of switching between blue system and transparent state and preparation method and application thereof
By preparing electrochromic compounds with thiophene structures and spraying them into films on ITO glass, the problem of the lack of electrochromic materials that can switch between blue and transparent states was solved. Rapid switching between blue and transparent states and high cycle stability were achieved, making it suitable for decorative displays and anti-counterfeiting labels.
Patent Information
- Application Number
- CN202510715501.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-30
- Publication Date
- 2025-09-05
AI Technical Summary
The existing technology lacks solution-processable electrochromic materials that can switch between a blue-transparent state, and cannot meet the unique needs of fields such as decorative displays and anti-counterfeiting labels.
Using electrochromic compounds with thiophene structure, electrochromic compounds that can switch between blue and transparent states are prepared through aromatic polycondensation reaction, including compounds PC-E and PE. Electrochromic films are prepared on ITO glass by spraying method.
The electrochromic performance of rapid switching between blue and transparent states was achieved. The optical contrast ratios of compounds PC-E and PE at a wavelength of 560nm were 6.12% and 43.94%, respectively. The compounds had good cycle stability and were suitable for the field of electronic price tags.
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Figure CN120590612A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of chemical materials, and specifically relates to electrochromic materials, and more specifically to electrochromic compounds that can switch between a blue-transparent state, as well as preparation methods and applications thereof, and electrochromic films that can switch between a blue-transparent state. Background Art
[0002] Electrochromic materials are functional materials that can reversibly change their optical properties (such as color and transmittance) under the action of an external electric field. They have broad application prospects in smart windows, anti-glare rearview mirrors, display devices, and other fields. Depending on their chemical composition, electrochromic materials can be divided into inorganic materials (such as WO3 and NiO) and organic materials (such as viologens and conductive polymers). Among them, organic electrochromic materials have become a research hotspot in recent years due to their advantages such as strong molecular structure designability, rich colors, and fast response speed.
[0003] Among organic electrochromic materials, solution-processable electrochromic materials have attracted widespread attention because they can be prepared on a large scale through low-cost, high-efficiency film-forming processes such as spraying. At present, solution-processable electrochromic material systems based on red-transparent state switching are relatively mature. For example, materials based on viologen derivatives or specific conjugated polymers have achieved high contrast and cyclic stability. However, research on solution-processable electrochromic materials that switch between blue-transparent states is still relatively scarce. As an important spectral color, blue has unique demands in the fields of decorative displays, anti-counterfeiting labels, etc. Therefore, it is necessary to develop an electrochromic compound that can switch between blue-transparent states and has good performance, which can be used to prepare electrochromic materials that can switch between blue and transparent. Summary of the Invention
[0004] In order to solve the problem that the existing technology lacks solution-processable electrochromic materials that can switch between a blue-transparent state, the present invention provides three solution-processable electrochromic compounds that can switch between a blue-transparent state with excellent optical and electrochromic properties, as well as their preparation methods and applications, and electrochromic films that can switch between a blue-transparent state.
[0005] The technical solution adopted by the present invention is: an electrochromic compound that can switch between a blue state and a transparent state, the compound having a thiophene structure, and the compound is any one of Formula I or Formula II:
[0006] It is abbreviated as compound PC-E;
[0007] Abbreviated as compound PE.
[0008] The present invention also provides a method for preparing the electrochromic compound, comprising: subjecting a thiophene derivative and a compound represented by Formula IV, 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin, to an arylation polycondensation reaction to obtain the electrochromic compound;
[0009] The thiophene derivatives are:
[0010] Compound 3 (3,4-dihydro-2H-thieno[3,4-b][1,4]dioxol-heptene-3,3-diyl)bis(methylene)bis(2-butyloctanoate) represented by formula III; or
[0011] A thiophene composition composed of a compound represented by Formula V, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene, and a compound represented by Formula VI, 6,8-dibromo-3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene;
[0012]
[0013]
[0014] Preferably, the preparation method comprises: under inert gas protection conditions, mixing the thiophene derivative, the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin shown in formula IV, potassium carbonate, pivalic acid, Pd(OAc)2, and anhydrous DMAc, reacting at 120-140° C. for 15-17 hours, and post-treating the reaction solution to obtain the electrochromic compound.
[0015] Preferably, the molar ratio of the thiophene derivative to the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by formula IV is 1 to 1.5:1.
[0016] Preferably, when preparing the compound PC-E represented by formula I, the molar ratio of the compound 3 (3,4-dihydro-2H-thieno[3,4-b][1,4]dioxol-heptene-3,3-diyl)bis(methylene)bis(2-butyloctanoate) represented by formula III to the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by formula IV is 1 to 1.1:1, more preferably 1:1.
[0017] Preferably, when preparing the compound PE represented by formula II, the molar ratio of the thiophene composition to the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by formula IV is 1.4 to 1.5:1, more preferably 1.5:1.
[0018] Preferably, in the thiophene composition, the molar ratio of the compound 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene shown in Formula V to the 6,8-dibromo-3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene shown in Formula VI is 4 to 6:1, more preferably 5:1.
[0019] Preferably, the molar ratio of potassium carbonate to the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by formula IV is 2 to 3:1, more preferably 2.5:1.
[0020] Preferably, the molar ratio of the pivalic acid to the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by Formula IV is 0.01 to 0.1:1, more preferably 0.04:1.
[0021] Preferably, the molar ratio of Pd(OAc)2 to the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by Formula IV is 0.01 to 0.05:1, more preferably 0.02:1.
[0022] Preferably, the volume of anhydrous DMAc added is 40 to 80 mL / g, more preferably 50 mL / g, based on the mass of the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by Formula IV.
[0023] Preferably, the post-treatment method is: adding the reaction solution to methanol, filtering, washing the filter cake with methanol, extracting the product from the filter cake using methanol, acetone, petroleum ether, and chloroform in sequence, and rotary evaporating the product extracted with chloroform to remove the solvent to obtain the electrochromic compound.
[0024] The present invention also provides the use of the electrochromic compound in preparing an electrochromic film that can switch between a blue-transparent state.
[0025] The present invention also provides an electrochromic film that can switch between a blue-transparent state. The electrochromic film is prepared by the following method: dissolving the electrochromic compound in an organic solvent (preferably chloroform), and then spraying it onto the conductive surface of ITO glass to form a film, thereby obtaining the electrochromic film that can switch between a blue-transparent state.
[0026] The present invention provides beneficial effects: Both thiophene-based electrochromic compounds capable of switching between two colors exhibit a blue hue in their reduced state and eventually transition to a transparent state with increasing applied voltage. Compound PC-E exhibits an optical contrast ratio of 6.12% at a wavelength of 560 nm, with a coloring time of 0.81 s and a fading time of 1.84 s. Compound PE exhibits an optical contrast ratio of 43.94% at a wavelength of 560 nm, with a coloring time of 0.51 s and a fading time of 0.81 s. After 1000 cycles at a step voltage of -0.6 V to 0.9 V, the optical contrast of the PC-E electrochromic film retained 94.49% of its initial contrast ratio. After 3000 cycles at a step voltage of -1.2 V to 0.8 V, the optical contrast of the PE electrochromic film retained 88.69% of its initial contrast ratio. These materials demonstrate excellent blue-to-transparent solution-processable electrochromic materials with promising applications in electronic price tags. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 The present invention provides two synthetic routes for electrochromic materials that can switch between a blue-transparent state.
[0028] Figure 2 This is the hydrogen spectrum of the compound PC-E represented by formula I prepared in Example 1 of the present invention.
[0029] Figure 3 This is the hydrogen spectrum of the compound PE represented by formula II prepared in Example 2 of the present invention.
[0030] Figure 4 CV curves of two electrochromic films switchable between a blue-transparent state and provided in Example 3 of the present invention.
[0031] Figure 5 These are UV-visible absorption spectra of two electrochromic films switchable between a blue-transparent state and provided in Example 3 of the present invention at different voltages.
[0032] Figure 6 The response time of two electrochromic films switchable between the blue and transparent states provided in Example 3 of the present invention in different wavelength bands.
[0033] Figure 7Dynamic tests of two electrochromic films switchable between the blue and transparent states provided in Example 3 of the present invention at different wavelengths.
[0034] Figure 8 The chromaticity of the two electrochromic films switchable between the blue and transparent states provided in Example 3 of the present invention at different voltages. DETAILED DESCRIPTION
[0035] The following describes the embodiments of the present invention by specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the case of no conflict, the features in the following examples and embodiments can be combined with each other. In the embodiments of the present invention, unless otherwise specified, the methods used are all conventional methods, and the reagents used can be obtained from commercial sources.
[0036] Example 1 Synthesis of Compound PC-E (Formula Ⅰ)
[0037] 3(3,4-dihydro-2H-thieno[3,4-b][1,4]dioxol-3,3-diyl)bis(methylene)bis(2-butyloctanoate) (580.41 mg, 1.0 mmol), 5,7-dibromo-2,3-dihydrothieno[3,4-b][1,4]dioxin (299.96 mg, 1.0 mmol), anhydrous potassium carbonate (345 mg, 2.5 mmol), pivalic acid (4.09 mg, 0.04 mmol) and Pd(OAc)2 (4.53 mg, 0.02 mmol) were weighed into a 15 mL Schlenk tube. Under nitrogen protection, 15 mL of anhydrous DMAc was added, the reaction was carried out at 130 ° C for 15 h, and then cooled to room temperature. The reaction solution was added to 300 ml of methanol and filtered with a Buchner funnel. The filter cake was washed with methanol. The filter cake was wrapped with filter paper and then extracted with a Soxhlet extractor to obtain polymers of different polymerization degrees. During the extraction, solvents with different solubility were replaced in the order of methanol, acetone, petroleum ether, and chloroform. Finally, the part extracted with chloroform was rotary evaporated to remove the solvent to obtain PC-E (Formula I). Its hydrogen spectrum is shown in FIG. Figure 2 .
[0038] Example 2 Synthesis of Compound PE (Formula II)
[0039] Weigh 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene (550.85 mg, 1.25 mmol), 6,8-dibromo-3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene (149.62 mg, 0.25 mmol), 5,7-dibromo-2 ,3-Dihydrothiophene[3,4-b][1,4]dioxin (299.96 mg, 1.0 mmol), anhydrous potassium carbonate (345 mg, 2.5 mmol), pivalic acid (4.09 mg, 0.04 mmol) and Pd(OAc)2 (4.53 mg, 0.02 mmol) were added to a 15 mL Schlenk tube. Under nitrogen protection, 15 mL of anhydrous DMAc was added, and the mixture was reacted at 130 ° C for 16 hours and cooled to room temperature. The reaction solution was added to 300 ml of methanol, filtered with a Buchner funnel, and the filter cake was washed with methanol. The filter cake was wrapped with filter paper and then extracted with a Soxhlet extractor to extract polymers of different polymerization degrees. During the process, solvents with different solubility were replaced. The order of solvent use was methanol, acetone, petroleum ether, and chloroform. Finally, the part extracted with chloroform was rotary evaporated to remove the solvent to obtain PE (Formula II), and its hydrogen spectrum is shown in FIG. Figure 3 .
[0040] Example 3 Preparation of two electrochromic films
[0041] 45 mg of compound PC-E or PE prepared in Example 1 or 2 was added to a 10 ml beaker, 3 ml of chloroform was added thereto, and the solution was shaken to mix evenly. Then, it was filtered using a microporous filter with a pore size of 0.45 μm, and then spin-coated on the conductive surface of 25*40 mm ITO glass using a spin coater (parameter setting: 1000 rpm / min, spin coating time 1 min) to obtain an electrochromic film.
[0042]
Performance test of electrochromic film
[0043] The electrochromic films prepared from the compound PC-E or PE in Example 3 were subjected to the following tests.
[0044] 1. Electrochemical testing
[0045] The electrochemical test was performed using a Chenhua 660 electrochemical workstation with the following parameters: CV mode, scan rates of 50 mv / s, 100 mv / s, 200 mv / s, 300 mv / s, and 500 mv / s, and scan ranges of 1.2 V and 0 V. Figure 4As shown in the figure, the electrochromic films made of PC-E or PE respectively have electrochemical responses within the scanning range, and their CV curves have quasi-reversible redox behavior.
[0046] 2. Optical and electrochromic performance test
[0047] The optical and electrochromic performance tests were conducted using a Chenhua 660 electrochemical workstation and a Shimadzu UV1800 UV-visible spectrophotometer. The test results are as follows: Figure 5 、 4 , as shown in 5.
[0048] like Figure 5 As shown in the figure, the maximum absorption peak of the two films in the neutral state (0.0V) is 560nm; as the voltage continues to increase, the original absorption peak gradually disappears, and shows double absorption characteristics in the visible light region (the trough of the absorption curve appears between 500 and 600nm); as the voltage continues to increase, the absorption curves of the two films in the visible light region have no obvious absorption peaks.
[0049] like Figure 6 and Figure 7 As shown, the optical contrast and cycle stability of the two films were tested in the maximum absorption peak band. The results showed that the optical contrast of PC-E in the 560nm wavelength range was 6.12%, the coloring time was 0.81s, and the fading time was 1.84s; the optical contrast of PE in the 560nm wavelength range was 43.94%, the coloring time was 0.51s, and the fading time was 0.81s. After 1000 cycles under a step voltage of -0.6V and 0.9V, the optical contrast of the PC-E electrochromic film can maintain 94.49% of the initial contrast; after 3000 cycles under a step voltage of -1.2V and 0.8V, the optical contrast of the PE electrochromic film can maintain 88.69% of the initial contrast.
[0050] 3. Chroma test
[0051] like Figure 8 As shown in FIG, at -0.8 V, both films appear blue, and as the voltage continues to increase, both films eventually become transparent.
[0052] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection of the present invention.
Claims
1. An electrochromic compound capable of switching between a blue-transparent state, characterized in that: The compound has a thiophene structure, and the compound is any one of Formula I or Formula II:
2. The method for preparing an electrochromic compound according to claim 1, wherein: include: The electrochromic compound is prepared by an arylation polycondensation reaction of a thiophene derivative and a compound represented by formula IV, 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin; The thiophene derivatives are: Compound 3 (3,4-dihydro-2H-thieno[3,4-b][1,4]dioxol-heptene-3,3-diyl)bis(methylene)bis(2-butyloctanoate) represented by formula III; or A thiophene composition composed of a compound represented by Formula V, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene, and a compound represented by Formula VI, 6,8-dibromo-3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene; 3. The method according to claim 2, wherein include: Under inert gas protection conditions, the thiophene derivative, the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by formula IV, potassium carbonate, pivalic acid, Pd(OAc)2, and anhydrous DMAc are mixed and reacted at 120-140° C. for 15-17 hours. The reaction solution is post-treated to obtain the electrochromic compound.
4. The method according to claim 3, wherein The molar ratio of the thiophene derivative to the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by formula IV is 1 to 1.5:1; In the thiophene composition, the molar ratio of the compound 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene represented by Formula V to the 6,8-dibromo-3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene represented by Formula VI is 4 to 6:
1.
5. The method according to claim 3, wherein The molar ratio of the potassium carbonate to the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by formula IV is 2 to 3:
1.
6. The method according to claim 3, wherein The molar ratio of the pivalic acid to the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by formula IV is 0.01 to 0.1:
1.
7. The method according to claim 3, wherein The molar ratio of the Pd(OAc)2 to the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by Formula IV is 0.01 to 0.05:1; and / or The added volume of the anhydrous DMAc is 40 to 80 mL / g based on the mass of the compound 5,7-dibromo-2,3-dihydrothiophene[3,4-b][1,4]dioxin represented by Formula IV.
8. The method according to claim 3, wherein The post-treatment method comprises: adding the reaction solution into methanol, filtering, washing the filter cake with methanol, extracting the product from the filter cake using methanol, acetone, petroleum ether, and chloroform in sequence, and rotary evaporating the product extracted with chloroform to remove the solvent, thereby obtaining the electrochromic compound.
9. Use of the electrochromic compound according to claim 1 or the electrochromic compound prepared by the method according to any one of claims 2 to 8 in preparing an electrochromic film switchable between a blue state and a transparent state.
10. An electrochromic film capable of switching between a blue-transparent state, characterized in that: The electrochromic film is prepared by the following method: dissolving the electrochromic compound according to claim 1 or the electrochromic compound prepared by any one of the methods of claims 2 to 8 in an organic solvent, and then spraying the resulting film on the conductive surface of ITO glass to obtain an electrochromic film that can switch between a blue state and a transparent state.