A transparent-blue switching electrochromic thin film and a preparation method thereof
Patent Information
- Application Number
- CN202610808097.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-05
- Publication Date
- 2026-08-21
AI Technical Summary
[0003]然而，现有许多电致变色材料的氧化还原（离子嵌入脱出）过程往往伴随着复杂的中间色态演变，容易出现黄、绿或红褐色等非预期的杂色过渡，这种中间色的存在不仅降低了视觉观感，也极大地限制了其应用场景
本发明在所述的电致变色薄膜在0V~1.1V的阶跃电压下具有快速响应：着色时间为1.8s，褪色时间为1.8s；在720nm波长范围下的最大光学对比度37.8%，经过200个循环仍能保持原对比度的58.2%，薄膜在透明态与饱和蓝色态之间表现出清晰的光学对比，未出现渐变的中间色调，这意味着器件能够在两个明确的光学状态间直接跳变，避免了色彩不均或调控模糊的问题，是一种有着极大应用潜力的电致变色薄膜。
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Figure CN122608846A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of functional polymer materials and electrochromic technology, and particularly to a transparent-blue switching electrochromic film and its preparation method. Background Technology
[0002] Electrochromic technology, as an advanced optoelectronic means that can dynamically regulate light and heat transfer, occupies a core position in the fields of optoelectronic devices and green energy conservation. Developing electrochromic films that combine high transparency (neutral state) and blue (colored state) not only better meets the visual comfort of the human eye but also effectively takes into account anti-glare and heat insulation functions. Furthermore, it meets the dual pursuit of aesthetics and functionality in modern optical devices.
[0003] However, the redox (ion insertion and extraction) process of many existing electrochromic materials is often accompanied by complex intermediate color state evolution, which can easily lead to unexpected color transitions such as yellow, green or reddish brown. The presence of such intermediate colors not only reduces the visual appeal but also greatly limits their application scenarios.
[0004] Therefore, it is of great significance to study an electrochromic film with transparent-blue switching that can ensure color purity, improve optical contrast, and optimize user experience, as well as its preparation method. Summary of the Invention
[0005] The purpose of this invention is to provide a transparent-blue switching electrochromic film and its preparation method, thereby solving the film formation problem of small molecule electrochromic materials in the prior art.
[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a transparent-blue switching electrochromic thin film, characterized in that the preparation method includes the following steps: 1) An electrochromic material is obtained by reacting a mixture of 9-(4-vinylphenyl)-9H-carbazole, acrylic acid, azobisisobutyronitrile and an organic solvent; 2) An electrochromic film is obtained by mixing electrochromic material, crosslinking agent and organic solvent.
[0007] Preferably, in step 1), the electrochromic material has the structural formula shown in Formula I:
[0008] Formula I; Where n ≥ 1 and is an integer.
[0009] Preferably, in step 1), the molar ratio of 9-(4-vinylphenyl)-9H-carbazole, acrylic acid, and azobisisobutyronitrile is 2~3.5:1:1~2.
[0010] Preferably, in step 1), the organic solvent is acetone or butanone; The ratio of 9-(4-vinylphenyl)-9H-carbazole to organic solvent is 30~40 mg:1 mL.
[0011] Preferably, in step 1), the reaction temperature is 60~80℃ and the reaction time is 24~30h.
[0012] Preferably, in step 2), the mass ratio of the electrochromic material to the crosslinking agent is 1:0.2~0.5; The crosslinking agent is a diazinon photocrosslinking agent.
[0013] Preferably, in step 2), the organic solvent is chloroform; The ratio of the electrochromic material to the organic solvent is 2~7 mg:1 mL.
[0014] Preferably, in step 2), the mixing is ultrasonic mixing, the ultrasonic mixing power is 45~60kHz, and the ultrasonic mixing time is 8~12min.
[0015] The present invention also provides an electrochromic film prepared by a method for preparing a transparent-blue switching electrochromic film.
[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: The electrochromic film of this invention exhibits a rapid response under a step voltage of 0V to 1.1V: the coloring time is 1.8s and the fading time is 1.8s; the maximum optical contrast ratio in the 720nm wavelength range is 37.8%, and it can still maintain 58.2% of the original contrast ratio after 200 cycles. The film shows a clear optical contrast between the transparent state and the saturated blue state, without the appearance of a gradual intermediate hue. This means that the device can directly switch between two distinct optical states, avoiding the problems of uneven color or ambiguous control. It is an electrochromic film with great application potential. Attached Figure Description
[0017] Figure 1 This is a synthetic route diagram of the electrochromic material described in this invention; Figure 2 The graph shows the cyclic voltammetric polymerization curve of the electrochromic thin film CZPAT obtained in Example 1. Figure 3 The following are the UV-Vis absorption spectra of the electrochromic film CZPAT obtained in Example 1 at different voltages; Figure 4The response time of the electrochromic thin film CZPAT obtained in Example 1 at 690 nm wavelength; Figure 5 The kinetics of the electrochromic thin film CZPAT obtained in Example 1 were tested in the 690 nm band. Detailed Implementation
[0018] This invention provides a method for preparing a transparent-blue switching electrochromic thin film, the method comprising the following steps: 1) An electrochromic material is obtained by reacting a mixture of 9-(4-vinylphenyl)-9H-carbazole, acrylic acid, azobisisobutyronitrile and an organic solvent; 2) An electrochromic film is obtained by mixing electrochromic material, crosslinking agent and organic solvent; In this invention, in step 1), the electrochromic material has the structural formula shown in Formula I:
[0019] Formula I; Where n ≥ 1 and is an integer.
[0020] In this invention, in step 1), the molar ratio of 9-(4-vinylphenyl)-9H-carbazole, acrylic acid and azobisisobutyronitrile is preferably 2~3.5:1:1~2, more preferably 2.5~3:1:1.2~1.8, and even more preferably 2.6~2.8:1:1.5~1.6.
[0021] In this invention, in step 1), the organic solvent is preferably acetone or butanone; The preferred ratio of 9-(4-vinylphenyl)-9H-carbazole to organic solvent is 30-40 mg:1 mL, more preferably 32-38 mg:1 mL, and even more preferably 35-36 mg:1 mL.
[0022] In this invention, in step 1), the reaction temperature is preferably 60~80℃, more preferably 65~75℃, and even more preferably 70~72℃, and the reaction time is preferably 24~30h, more preferably 25~29h, and even more preferably 26~28h.
[0023] In this invention, in step 1), the reaction is preferably carried out by stirring and reflux, and the reaction is preferably carried out under a nitrogen atmosphere.
[0024] In this invention, in step 1), the structural formula of the 9-(4-vinylphenyl)-9H-carbazole is shown in Formula II:
[0025] Formula II; The structural formula of the acrylic acid is shown in Formula III:
[0026] Formula III.
[0027] In this invention, in step 1), the reaction product is preferably washed, allowed to stand and filtered, and purified sequentially after the reaction. The washing reagent was an aqueous solution of icy methanol; after washing, the organic phases were combined and allowed to stand for filtration, and then the resulting organic phase was purified. The purification method is preferably Soxhlet extraction, and the organic phase used is preferably methanol or acetone.
[0028] In this invention, in step 2), the mass ratio of the electrochromic material to the crosslinking agent is preferably 1:0.2~0.5, more preferably 1:0.3~0.4, and even more preferably 1:0.35~0.38; The crosslinking agent is preferably a diazinon photocrosslinking agent, which is 4,4'-oxobis(1-(3-trifluoromethyl-3H-bisazinon-3-yl)phenyl) (as shown in Formula IV), 2,7-bis(4-(3-trifluoromethyl-3H-bisazinon-3-yl)phenyl)-9,9-dihexyl-9H-fluorene (as shown in Formula V) or 2CNN (as shown in Formula VI), preferably 2CNN.
[0029]
[0030] Formula IV
[0031] Formula V
[0032] Formula VI
[0033] In this invention, in step 2), the organic solvent is preferably trichloromethane; The preferred ratio of the electrochromic material to the organic solvent is 2-7 mg:1 mL, more preferably 3-6 mg:1 mL, and even more preferably 4-5 mg:1 mL.
[0034] In this invention, in step 2), the mixing is preferably ultrasonic mixing, the ultrasonic mixing power is preferably 45~60kHz, more preferably 48~55kHz, more preferably 50~55kHz, and the ultrasonic mixing time is preferably 8~12min, more preferably 9~11min, and more preferably 10min.
[0035] In this invention, step 2) is preferably performed under light-protected conditions.
[0036] In this invention, in step 2), after mixing, it is preferable to use a spray gun to spray the solution onto ITO glass to form a film, and then place the film under a 365nm ultraviolet lamp for 2-3 minutes. After that, the film surface is rinsed with dichloromethane-acetonitrile solution to wash away the incompletely cross-linked parts, and then air-dried naturally. In the dichloromethane-acetonitrile solution, the volume ratio of dichloromethane to acetonitrile is 4:6.
[0037] In this invention, the obtained electrochromic material exhibits good solubility in conventional solvents such as chloroform, facilitating film formation using solution processing techniques (such as spin coating and spray coating). The process is simple and suitable for large-scale production. After film formation, efficient crosslinking can be triggered by adding an appropriate amount of a bisacrylidine-based photocrosslinking agent and irradiating with light. The only byproduct of this process is nitrogen gas, making it environmentally friendly.
[0038] The present invention also provides an electrochromic film prepared by a method for preparing a transparent-blue switching electrochromic film.
[0039] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0040] Example 1
[0041] Weigh 300 mg (1.11 mmol) of 9-(4-vinylphenyl)-9H-carbazole, 26.75 mg (0.371 mmol) of acrylic acid, and 91.136 mg (0.555 mmol) of azobisisobutyronitrile (AIBN) and add them sequentially to 35 mL reaction tubes. Under nitrogen protection, add 5 mL of acetone and heat under reflux at 70 °C for 28 h. Then, wash the resulting mixture thoroughly with a mixture of ice-cold methanol and deionized water. Combine the organic phases, allow them to stand, and filter. Purify the organic phase with methanol by Soxhlet extraction to obtain the target product 4-(4-(9H-carbazole-9-yl)phenyl)-3-methylpentanoic acid (CZPA). Weigh out 5 mg of CZPA and 4 mg of bisacodyl photocrosslinking agent 2CNN and dissolve them in 1 mL of chloroform. Spray the solution onto an ITO glass film using a spray gun. Then, irradiate the film under a 365 nm UV lamp for 2 min. After that, rinse the film surface with a dichloromethane-acetonitrile solution (dichloromethane to acetonitrile volume ratio of 4:6) to remove the incompletely crosslinked parts. Allow it to air dry to obtain the electrochromic film CZPAT.
[0042] The following performance tests were performed on the CZPAT color-changing film obtained in Example 1: Electrochemical tests were performed using a Chenhua 660 electrochemical workstation and a three-electrode system. ITO glass coated with a transparent-blue electrochromic film was used as the working electrode, platinum wire as the counter electrode, and Ag / AgCl as the reference electrode. A 0.1M tetrabutylhexane ammonium / acetonitrile solution was used as the test solution. CV curves of CZPAT at different scan rates were obtained by adjusting the scan rate. The results are as follows: Figure 2 As shown.
[0043] The cyclic voltammetric polymerization curve of the electrochromic thin film CZPAT obtained in Example 1 is shown in Figure 1. Figure 2 As shown. By Figure 2 As can be seen, the peak current gradually increases with the increase of the scan rate, which proves that the thin film can be well attached to the ITO glass.
[0044] Optical and electrochromic properties were tested using a Chenhua 660 electrochemical workstation coupled with a UV-Vis spectrophotometer.
[0045] Different voltages were applied using a Chenhua 660 electrochemical workstation, and a UV-Vis spectrophotometer was used to scan the wavelength range of 300–1100 nm to obtain UV-Vis absorption spectra at different voltages. The results are shown below. Figure 3 As shown.
[0046] The UV-Vis absorption spectra of the electrochromic thin film CZPAT obtained in Example 1 at different voltages are shown below. Figure 3 As shown. By Figure 3 It can be seen that the polymer film is colorless and transparent in the neutral state; it exhibits a blue state under oxidation voltage; and it has electrochromic properties with high optical contrast.
[0047] The response time of the electrochromic thin film CZPAT obtained in Example 1 at 690 nm wavelength is as follows: Figure 4 As shown. The kinetics of the electrochromic thin film CZPAT obtained in Example 1 at the 690nm wavelength are as follows. Figure 5 As shown. By Figure 4 and Figure 5 As can be seen, when a step voltage of 0V and 1.1V is applied to the thin film, the performance test results show that the coloring time of the thin film is 1.8s and the fading time is 1.8s under the step voltage; the optical contrast ratio in the 690nm wavelength range is 37.8, and it can still maintain 58.2% of the original contrast ratio after 200 cycles.
[0048] Therefore, the strategy of using a non-conjugated main chain combined with side chains to suspend electrochromic groups can not only prepare neutral, highly transparent polymer electrochromic films, but also combine photocrosslinking technology to construct a network crosslinking network, thereby obtaining electrochromic polymer materials with excellent comprehensive performance.
[0049] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a transparent-blue switching electrochromic thin film, characterized in that, The preparation method includes the following steps: 1) An electrochromic material is obtained by reacting a mixture of 9-(4-vinylphenyl)-9H-carbazole, acrylic acid, azobisisobutyronitrile and an organic solvent; 2) An electrochromic film is obtained by mixing electrochromic material, crosslinking agent and organic solvent.
2. The method for preparing a transparent-blue switching electrochromic thin film according to claim 1, characterized in that, In step 1), the structural formula of the electrochromic material is shown in Formula I: Formula I; Where n ≥ 1 and is an integer.
3. The method for preparing a transparent-blue switching electrochromic thin film according to claim 1, characterized in that, In step 1), the molar ratio of 9-(4-vinylphenyl)-9H-carbazole, acrylic acid, and azobisisobutyronitrile is 2~3.5:1:1~2.
4. The method for preparing a transparent-blue switching electrochromic thin film according to claim 1 or 3, characterized in that, In step 1), the organic solvent is acetone or butanone; The ratio of 9-(4-vinylphenyl)-9H-carbazole to organic solvent is 30~40 mg:1 mL.
5. The method for preparing a transparent-blue switching electrochromic thin film according to claim 4, characterized in that, In step 1), the reaction temperature is 60~80℃ and the reaction time is 24~30h.
6. The method for preparing a transparent-blue switching electrochromic thin film according to claim 1, characterized in that, In step 2), the mass ratio of the electrochromic material to the crosslinking agent is 1:0.2~0.5; The crosslinking agent is a diazinon photocrosslinking agent.
7. The method for preparing a transparent-blue switching electrochromic thin film according to claim 6, characterized in that, In step 2), the organic solvent is chloroform; The ratio of the electrochromic material to the organic solvent is 2~7 mg:1 mL.
8. The method for preparing a transparent-blue switching electrochromic thin film according to claim 6 or 7, characterized in that, In step 2), the mixing is ultrasonic mixing, the ultrasonic mixing power is 45~60kHz, and the ultrasonic mixing time is 8~12min.
9. An electrochromic film prepared by the method for preparing a transparent-blue switching electrochromic film according to any one of claims 1 to 8.