Preparation method and application of terpyridine electrochromic compound film capable of displaying green

Abstract

The present invention provides a method for preparing a terpyridine electrochromic compound film that can display green and its application. The present invention can prepare different color-changing film materials with terpyridine as the main structure by changing the cross-linking addition amount of terpyridine, and the film material can be combined with an ionic liquid gel electrolyte and applied to the field of optoelectronic functional intelligent devices. The terpyridine electrochromic compound film prepared by the present invention has good electrochemical stability. After being combined with a gel electrolyte formed by an ionic liquid and a supporting polymer, the assembled device can achieve a rapid display from colorless to green, and at the same time has good electrochemical and reversible cycle stability. The terpyridine electrochromic compound film of the present invention is used as an electrochromic material in combination with a gel electrolyte composed of an ionic liquid and a supporting polymer and is applied to an electrochromic device that can display green color.

Description

Technical Field

[0001] The invention belongs to the technical field of optoelectronic functional film materials, and relates to an electrochromic compound, in particular to a terpyridine electrochromic compound film capable of displaying green. Background Art

[0002] In recent years, electrochromic materials used in electrochromic smart windows and smart displays have attracted widespread attention from researchers and the industry as a new type of optoelectronic functional material. This type of optoelectronic smart material can undergo reversible color changes under a certain external bias, and has rich colors and diverse functions. Pyridine-structured color-changing materials have broad practical application prospects due to their strong designability, large light modulation range and rich colors.

[0003] At the same time, ionic liquids have been widely used in gel electrolytes of electrochromic electrochemical devices due to their high ionic conductivity, negligible volatility, wide electrochemical window and electrochemical stability. On the other hand, the application of ionic liquid gel electrolytes in electrochromic electrochemical devices composed of pyridine-structured color-changing materials can not only achieve multi-color display, but also achieve high and low temperature resistance and weather resistance of the device. The combination of pyridine-structured color-changing materials and ionic liquid gel electrolytes makes it possible to realize the practical industrial application of color-changing devices in smart windows and smart displays.

[0004] However, most of the existing devices composed of color-changing materials have difficulty in achieving green display, making it difficult to achieve smart display based on the three primary colors. Summary of the invention

[0005] In order to solve the problems of the prior art, the purpose of the present invention is to provide a terpyridine electrochromic compound film that can display green. By combining the compound film with an ionic liquid gel electrolyte, not only the green display of the device is achieved, but the device also has a larger light modulation range and a faster electrochromic response rate.

[0006] In order to achieve the above technical objectives, the present invention first provides a terpyridine electrochromic compound that can display green, and the terpyridine electrochromic compound has a structure as shown in (I):

[0007]

[0008] Wherein, y=0.1-1.0, X is Cl, Br, I, ClO4, PF6, BF4, CF3COO or CH3COO.

[0009] In order to achieve the above technical objectives, the present invention also provides a method for preparing the above terpyridine electrochromic compound, which comprises the following steps:

[0010]

[0011] At the same time, in order to achieve the above technical purpose, the present invention also provides a method for preparing the above ionized polyphenylene ether (II) with different grafting rates, the preparation method comprising the following steps:

[0012] Preferably, the grafting rate is 10%-80%.

[0013] Add the compounds represented by formula (II) and (III) to N,N-dimethylformamide, and react on a heating plate at 40-100° C. for 3-24 hours to obtain the terpyridine electrochromic compound capable of displaying green; the molar mass ratio of the compounds represented by formula (II) and (III) is 1:(0.1-1);

[0014] The volume amount of the N,N-dimethylformamide is 10-20 mL / g based on the mass of the substance represented by formula (II);

[0015] Among them, among them, y=0.1-1.0.

[0016] In a specific embodiment of the present invention, the volume amount of N,N-dimethylformamide is 10-20 mL / g based on the mass of the substance represented by formula (II).

[0017] In another specific embodiment of the present invention, the substance represented by formula (II) is prepared specifically according to the following steps:

[0018] Dissolve polyphenylene ether, N-bromosuccinimide and azobisisobutyronitrile in chlorobenzene, and stir the solution to dissolve at room temperature to obtain solution A. Solution A is reacted at 80-150° C. in a nitrogen atmosphere for 12-36 hours. After the reaction is completed, reaction solution B is obtained, and the substance represented by formula (II) is obtained through post-treatment.

[0019] The volume amount of chlorobenzene is 10-100 mg / mL based on the mass of polyphenylene ether; the ratio between the amount of the feed materials of polyphenylene ether and N-bromosuccinimide is 1:(0.1-1); the mass amount of azobisisobutyronitrile is 0.001-0.4 g / g based on the mass of polyphenylene ether;

[0020] Furthermore, the post-treatment method of the reaction solution B is:

[0021] The reaction solution B cooled to room temperature is dropped into a large amount of anhydrous ethanol solution, filtered, the filter residue is collected and washed three times with anhydrous ethanol, the solvent is evaporated under reduced pressure and fully dried to obtain the intermediate product represented by formula (II).

[0022] In another specific embodiment of the present invention, the intermediate product represented by formula (III) is prepared according to the following steps:

[0023] Benzaldehyde, 2-acetylpyridine and ammonia water are added to anhydrous ethanol for mixing and dissolving at room temperature, potassium hydroxide is slowly added dropwise to the solution, and the reaction is continued at 40-90° C. for 24-48 hours to obtain a reaction solution C, which is post-treated to obtain an intermediate product represented by formula (III); the volume amount of the anhydrous ethanol is recorded as 1-3 mL / mmol based on the amount of benzaldehyde; the ratio between the amount of the feed materials of the benzaldehyde and the 2-acetylpyridine is 1:1-5; the volume amount of the concentrated ammonia water is recorded as 1-3 mL / mmol based on the amount of the benzaldehyde; the concentration of the potassium hydroxide solution is 10-50%, and the ratio between the amount of the feed materials of the benzaldehyde and the potassium hydroxide is 1:1-5.

[0024] Furthermore, the post-treatment method of the reaction solution C is: adding glacial acetic acid to the reaction solution C cooled to room temperature, adjusting the pH of the solution C to 6-7, filtering and washing the precipitated solid with methanol until it turns white, and distilling off the solvent under reduced pressure to obtain the intermediate product represented by formula (III).

[0025] In one embodiment of the present invention, the terpyridine electrochromic compound film containing the structure shown in (I) is prepared according to the following steps:

[0026] The intermediate product compounds of the structures shown in formula (II) and (III) are dissolved in N, N-dimethylformamide, stirred at room temperature for 12-36 hours to obtain a mixed solution D, and the mixed solution D is spread on a transparent conductive ITO glass or PET substrate, and the solvent is dried on a flat plate heated at 80°C; the molar ratio of the compounds shown in formula (II) and (III) is 1:0.1-1; the volume amount of the N, N-dimethylformamide is 10-20 mL / g based on the mass of the substance shown in formula (II);

[0027] In addition, in order to achieve the above technical objectives, the present invention also provides a gel electrolyte containing ionic liquid, wherein the gel electrolyte includes an ionic liquid solvent and a supporting polymer, the ionic liquid cation is one or more of imidazolium cation, pyrrole cation, morpholinium cation, piperidinium cation, pyridinium cation, pyrazolium cation, and carbazole cation; the anion of the ionic liquid salt is one or more of chloride, bromide, iodine, hexafluorophosphate, tetrafluoroborate, bistrifluoromethanesulfonimide, trifluoromethanesulfonimide, acetate, trifluoroacetate, and perchlorate; the supporting polymer in the gel electrolyte is one or more of polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polyvinylidene fluoride, poly(vinylidene fluoride-hexafluoropropylene), polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl acetate.

[0028] The present invention also provides an electrochemical device capable of displaying green, the electrochemical device comprising a conductive substrate containing a terpyridine electrochromic compound film capable of displaying green and a gel electrolyte layer containing an ionic liquid sandwiched between the two substrates, wherein the terpyridine electrochromic compound film is prepared by heating, casting and cross-linking the compounds of the structures shown in formula (II) and (III) to form a film;

[0029] The present invention provides a method for preparing a terpyridine electrochromic compound and a film thereof that can display green. By changing the cross-linking addition amount of terpyridine, different color-changing film materials with terpyridine as the main structure can be prepared, and the film material can be combined with an ionic liquid gel electrolyte and applied to the field of optoelectronic functional intelligent devices.

[0030] The terpyridine electrochromic compound film prepared by the present invention has good electrochemical stability. After being combined with a gel electrolyte formed by an ionic liquid and a supporting polymer, the assembled device can achieve a rapid display from colorless to green, and has good electrochemical and reversible cycle stability.

[0031] The terpyridine electrochromic compound film as shown in formula (I) of the present invention is used as an electrochromic material in combination with a gel electrolyte composed of an ionic liquid and a supporting polymer and is applied to an electrochromic device that can display green color.

[0032] The electrochemical device with green display described in the present invention has the characteristics of faster color change response rate and stable color change, and has potential application prospects in the fields of smart displays, smart windows and electrochemical energy storage.

[0033] The terpyridine electrochromic compound film of the present invention contains a pyridine electrochromic compound, and the terpyridine electrochromic compound film has a faster electrochromic response speed and a higher reversible cycle stability, and can be used as a universal membrane material to prepare a sandwich-type electrochemical intelligent color-changing device, which is beneficial to reducing production steps and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the structure of an electrochemical device based on a terpyridine electrochromic compound film in an embodiment of the present invention.

[0035] Figure 2 Two-electrode cyclic voltammetry curve of the electrochemical device of the terpyridine electrochromic compound film in Example 8 of the present invention.

[0036] Figure 3 The electrochemical device spectral modulation performance of the terpyridine electrochromic compound film in Example 8 of the present invention.

[0037] Figure 4 The color change response time of the electrochemical device of the terpyridine electrochromic compound film in Example 8 of the present invention.

[0038] Figure 5 The color change response time of the electrochromic electrochemical device in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0039] The present invention adopts the Swiss Metrohm electrochemical workstation, and ultraviolet-visible spectroscopy characterizes the electrochemical and optical properties of the obtained terpyridine electrochromic compound film electrochemical device.

[0040] Example 1

[0041] Synthesis of 20% Brominated Polyphenylene Ether

[0042] Polyphenylene ether (15 mmol, 1.8 g), N-bromosuccinimide (3.8 mmol, 1.18 g) and azobisisobutyronitrile (0.18 g) were dissolved in 50 mL of chlorobenzene, and the solution was fully stirred and dissolved at room temperature. The resulting solution was reacted at 135°C for 15 h in a nitrogen atmosphere. After the reaction was completed, the reaction solution cooled to room temperature was dropped into a large amount of anhydrous ethanol solution, filtered, and the filter residue was collected and washed three times with anhydrous ethanol. The solvent was evaporated under reduced pressure and fully dried to obtain a 20% brominated polyphenylene ether intermediate product shown in formula (II) with a yield of 91.6%.

[0043] Example 2

[0044] Synthesis of 40% Brominated Polyphenylene Ether

[0045] Polyphenylene ether (15 mmol, 1.8 g), N-bromosuccinimide (7.5 mmol, 1.34 g) and azobisisobutyronitrile (0.18 g) were dissolved in 100 mL of chlorobenzene, and the solution was fully stirred and dissolved at room temperature. The resulting solution was reacted at 135° C. for 15 h in a nitrogen atmosphere. After the reaction, the reaction solution cooled to room temperature was dropped into a large amount of anhydrous ethanol solution, filtered, and the filter residue was collected and fully washed three times with anhydrous ethanol. The solvent was evaporated under reduced pressure and fully dried to obtain a 40% brominated polyphenylene ether intermediate product shown in formula (II) with a yield of 93.8%.

[0046] Example 3

[0047] Synthesis of 60% Brominated Polyphenylene Ether

[0048] Polyphenylene ether (45mmol, 5.4g), N-bromosuccinimide (31.5mmol, 5.61g) and azobisisobutyronitrile (0.054g) were dissolved in 150mL of chlorobenzene, and the solution was fully stirred and dissolved at room temperature. The resulting solution was reacted at 135°C for 15h in a nitrogen atmosphere. After the reaction was completed, the reaction solution cooled to room temperature was dropped into a large amount of anhydrous ethanol solution, filtered, and the filter residue was collected and fully washed three times with anhydrous ethanol. The solvent was evaporated under reduced pressure and fully dried to obtain a 60% brominated polyphenylene ether intermediate product shown in formula (II) with a yield of 95.8%. 1 H NMR (400MHz, CDCl3) δ6.97–6.32(m,1H),4.34(s,0.6H),2.34–1.84(m,3H).

[0049]

[0050] Example 4

[0051] Synthesis of terpyridine

[0052] Benzaldehyde (1.05 g, 10 mmol), 2-acetylpyridine (2.42 g, 20 mmol) and 20 mL of concentrated aqueous ammonia were added to 15 mL of anhydrous ethanol, mixed and dissolved at room temperature, potassium hydroxide solution (33%, 3.9 mL) was slowly added dropwise to the solution, and the reaction was continued at 50°C for 36 h to obtain reaction solution C. Glacial acetic acid was added to the reaction solution C cooled to room temperature, and the pH of solution C was adjusted to 6-7. The precipitated solid was fully filtered and washed with methanol until it turned white, and the solvent was evaporated under reduced pressure to obtain the intermediate product represented by formula (III) with a yield of 95.6%. 1 H NMR (400MHz, CDCl3) δ8.80(d,4H),8.19–7.95(m,6H),7.73(t,2H),7.57(dd,2H),7.27(s,1H).

[0053]

[0054] Example 5

[0055] Synthesis of Benzyl Disubstituted Terpyridinium Salts

[0056] The intermediate product (5 mmol) of formula (III) and benzyl bromide (12.5 mmol) were dissolved in chloroform, and the reaction was refluxed for 12 hours. The obtained reaction solution was filtered and the residue was fully washed with chloroform to obtain benzyl disubstituted terpyridine bromide with a yield of 85.3%. Anion exchange was obtained by dissolving benzyl disubstituted terpyridine bromide and potassium hexafluorophosphate (molar ratio of 1:3) in water at the same time and stirring for 12 hours. The residue was filtered and fully washed with deionized water to obtain the final product benzyl disubstituted terpyridine hexafluorophosphate shown in formula (IV) with a yield of 94.2%. 1 H NMR(400MHz,DMSO-d6)δ9.42(t,J=22.8Hz,4H),9.12(dd,J=39.6,7.5Hz,4H),9.01–8 .77(m,2H),8.29–7.99(m,2H),7.58(t,J=8.5Hz,7H),7.53–7.24(m,6H),5.95(s,4H).

[0057]

[0058] Example 6

[0059] Preparation of 20% Substituted Terpyridine Polyphenylene Ether Film

[0060] 20% brominated polyphenylene ether (1 mmol, 0.168 g) represented by formula (II) was dissolved in 35 mL N, N-dimethylformamide, and the compound represented by formula (III) (0.17 mmol, 0.05 g) was added to the mixture, which was spread on the conductive surface of a conductive substrate on a heating plate at 80°C and reacted for 24 hours to obtain a 20% substituted terpyridine electrochromic compound film represented by formula (I) that can display green.

[0061] Example 7

[0062] Preparation of 40% Substituted Terpyridine Polyphenylene Ether Film

[0063] 40% brominated polyphenylene ether (1 mmol, 0.168 g) represented by formula (II) was dissolved in 35 mL N, N-dimethylformamide, and the compound represented by formula (III) (0.34 mmol, 0.1 g) was added to the mixture, which was spread on the conductive surface of a conductive substrate on a heating plate at 80°C and reacted for 24 hours to obtain a 40% substituted terpyridine electrochromic compound film represented by formula (I) that can display green.

[0064] Example 8

[0065] Preparation of 60% Substituted Terpyridine Polyphenylene Ether Film

[0066] A 60% brominated polyphenylene ether (1 mmol, 0.168 g) represented by formula (II) was dissolved in 35 mL of N, N-dimethylformamide, and a compound represented by formula (III) (0.5 mmol, 0.155 g) was added to the mixture, which was spread on the conductive surface of a conductive substrate on a heating plate at 80°C and reacted for 24 hours to obtain a 60% substituted terpyridine electrochromic compound film represented by formula (I) that can display green.

[0067] It has been verified that the electrochromic compound film with 60% substitution of terpyridine has the best effect.

[0068] Example 9

[0069] This embodiment provides a terpyridine electrochromic compound film and an electrochemical device thereof that can display green color, such as Figure 1 The device comprises two conductive substrates 1 and 2 arranged in parallel and correspondingly, a terpyridine electrochromic compound film 3 on the conductive substrate, and an ionic liquid gel electrolyte 4 formed between the two conductive substrates. The specific manufacturing process is as follows: the ionic liquid gel electrolyte 4 is placed between the conductive surfaces of two conductive substrates (ITO-glass) 1 and 2, and the edges are sealed with a two-component sealant;

[0070] The preparation method of the above ionic liquid gel electrolyte 4 is as follows: poly(vinylidene fluoride-hexafluoropropylene) (0.1 g) is dissolved in 1-methyl-1-propylpyrrolidine bistrifluoromethanesulfonyl imide ionic liquid (2.0 g), and the mixture is stirred at 60° C. for 10 h to obtain an ionic liquid gel electrolyte.

[0071] Comparative Example 1

[0072] This comparative example provides an electrochromic electrochemical device, which is basically the same as that in Example 5, except that: the device includes two conductive substrates 1 and 2 arranged in parallel and corresponding to each other and an ionic liquid gel electrolyte 4 formed between the two conductive substrates; the specific manufacturing process is: the ionic liquid gel electrolyte 4 is placed between the conductive surfaces of two conductive substrates (ITO-glass) 1 and 2, and the edges are sealed with a two-component sealant;

[0073] The preparation method of ionic liquid gel electrolyte 4 is as follows: dissolve benzyl disubstituted terpyridine hexafluorophosphate (70 mg), ferrocene (7.5 mg), and poly(vinylidene fluoride-hexafluoropropylene) (0.1 g) in 1-methyl-1-propylpyrrolidine bistrifluoromethanesulfonyl imide ionic liquid (2.0 g), and stir thoroughly at 50°C for 5 hours to obtain an ionic liquid gel electrolyte.

[0074] like Figure 2-5 As shown, the step voltage of cyclic voltammetry, spectroelectrochemistry and electrochromic test is 0-3.0V. The test results of the terpyridine electrochromic compound film and its device that can display green show that it has bright green change (a strong 80% transmittance difference at 490-550nm, and very small transmittance in other bands), fast color change response speed (about 5s) and excellent spectral modulation characteristics and practicality. At about 550nm, the transmittance change (the difference between the initial state transmittance and the color change state transmittance) of the terpyridine electrochromic compound film device is about 80%. And its color change response time and fading response time are both short, about 5s and 9s respectively. The device response time of Comparative Example 1 (terpyridine color-changing material and ferrocene dissolved in electrolyte) is longer than that of the device in Example 5 (especially the color change response time is about four times that of the device in Example 5), which is very unfavorable for the practical application of the device in fast response scenarios (such as display, sensing and electronic paper, etc.).

[0075] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A terpyridine electrochromic compound capable of displaying green, characterized in that The terpyridine electrochromic compound has a structure as shown in (I): Wherein, y=0.1-1.0, X is Cl, Br, I, ClO4, PF6, BF4, CF3COO or CH3COO.

2. A method for preparing a terpyridine electrochromic compound film capable of displaying green, characterized in that: The terpyridine electrochromic compound film comprises the terpyridine electrochromic compound capable of displaying green as claimed in claim 1; The film preparation method comprises hot casting film formation, spin coating film formation or scraping film formation; the solvent used in the film preparation method is one or a combination of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate and γ-butyrolactone.

3. The method for preparing a terpyridine electrochromic compound film capable of displaying green according to claim 2, characterized in that: The mass of the terpyridine electrochromic compound is recorded as 0.01-1 mg / mL based on the solvent volume; the temperature required for drying the solvent for the hot casting film, spin coating film or blade coating film is 50-100°C.

4. The method for preparing a terpyridine electrochromic compound film capable of displaying green according to claim 2 or 3, characterized in that: The method comprises the following steps: Add the compounds represented by formula (II) and (III) to N,N-dimethylformamide, and react on a heating plate at 40-100° C. for 3-24 hours to obtain the terpyridine electrochromic compound capable of displaying green; The molar mass ratio of the compounds represented by formula (II) and (III) is 1:0.1-1; Among them, y=0.1-1.

0.

5. The method for preparing a terpyridine electrochromic compound film capable of displaying green according to claim 4, characterized in that: The volume amount of the N,N-dimethylformamide is 10-20 mL / g based on the mass of the substance represented by formula (II).

6. An electrochemical device comprising a terpyridine electrochromic compound film capable of displaying green, characterized in that The device should include a terpyridine electrochromic compound film that can display green obtained by the preparation method as claimed in claim 2 and a gel electrolyte with a certain ionic conductivity.

7. An electrochemical device comprising a terpyridine electrochromic compound film capable of displaying green according to claim 6, characterized in that The solvent of the gel electrolyte is one or more of water, propylene carbonate, ethylene carbonate, acetonitrile, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, and dimethyl carbonate; the electrolyte salt in the gel electrolyte is one or more of lithium salt, potassium salt, sodium salt, and ionic liquid; the mass of the electrolyte salt in the gel electrolyte is 0.1-5.0 g / mL based on the volume of the solvent.

8. The electrochemical device comprising a terpyridine electrochromic compound film capable of displaying green color according to claim 6, characterized in that: The cations of the electrolyte ion liquid salt in the gel electrolyte are one or more of imidazolium cations, pyrrole cations, morpholinium cations, piperidinium cations, pyridinium cations, pyrazolium cations, and carbazole cations; the anions of the electrolyte ion liquid salt in the gel electrolyte are one or more of chloride, bromine, iodine, hexafluorophosphate, tetrafluoroborate, bistrifluoromethanesulfonimide, trifluoromethanesulfonimide, acetate, trifluoroacetate, and perchlorate.

9. The electrochemical device comprising a terpyridine electrochromic compound film capable of displaying green color according to claim 6, characterized in that: The supporting polymer in the gel electrolyte is one or more of polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polyvinylidene fluoride, poly(vinylidene fluoride-hexafluoropropylene), polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl acetate.

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