Preparation and extraction method of electrode for electrochromic device

Abstract

The invention discloses a preparation method of an electrode for an electrochromic device, and the preparation method comprises the following steps: S1, mixing a water-soluble polyurethane emulsion with isopropanol, stirring until the mixture is uniformly mixed, and filtering to obtain a mask plate precursor solution; s2, the mask plate precursor solution forms a wet film on the upper surface of a substrate through a coating process, heating is conducted firstly, after heat preservation is conducted for a time enough for drying a film layer, the film layer is taken out and cooled, and random cracks are formed on the surface of the film; and S3, successively depositing a metal seed layer Cu and a metal layer Ag on the surface of the film, and then removing the template layer generated by the film to obtain the electrode for the electrochromic device. By means of the method, the electrochromic device which is shorter in coloring and fading state time and more stable can be prepared.

Description

Technical Field

[0001] This invention relates to the field of electronic technology, and specifically to a method for preparing and extracting electrodes for electrochromic devices. Background Technology

[0002] Electrochromic devices are devices that alter the color or optical properties of electrochromic materials by driving a reversible oxidation-reduction reaction through an applied electric field. Typically, electrochromic devices consist of a conductive layer, an electrochromic layer, an electrolyte layer, and an ion storage layer. They can actively block heat loss caused by indoor temperature differences by controlling the voltage, effectively reducing energy consumption. Furthermore, they can adjust visible light transmittance. Therefore, they have wider applications in fields such as smart windows, display devices, and thermal control equipment.

[0003] Currently, most research focuses on the electrochromic layer and electrolyte layer to improve the response time of electrochromic devices. However, there is less attention paid to how to develop new electrodes and how to introduce external power supply voltage to electrochromic devices to achieve faster and more stable coloring and fading states.

[0004] Existing technologies such as CN107957646A propose an electrochromic device with four electrode layers, achieving precise color change through partitioned conductive layers; CN115981065A proposes a bonding method for lead-out electrodes, simplifying the connection process. However, both of these methods focus on improving the device structure or connection structure, and do not fundamentally solve the problem of high lateral transport resistance in traditional transparent electrode layers, which leads to long electrochromic response time. In addition, the complex device structure also increases the processing difficulty, thereby increasing the production cost for enterprises.

[0005] To address this issue, we provide a method for preparing electrodes for electrochromic devices. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention provides a method for preparing electrodes for electrochromic devices, which can produce electrochromic devices with faster and more stable coloring and fading states.

[0007] To achieve the above objectives, the present invention provides a method for preparing an electrode for an electrochromic device, comprising the following steps: S1, mix water-soluble polyurethane emulsion and isopropanol, stir until uniformly mixed and then filter to obtain mask precursor liquid; S2, the mask precursor liquid is coated to form a wet film on the upper surface of the substrate. It is first heated and kept at a temperature sufficient to dry the film layer. Then it is taken out and cooled to form random cracks on the surface of the film. S3, deposit a metal seed layer Cu and a metal layer Ag on the surface of the above thin film, and then remove the template layer generated by the thin film to obtain the electrode for electrochromic device.

[0008] As a further optimization of the above scheme, the preparation step of the water-soluble polyurethane emulsion in step S1 is as follows: S101, dissolve polycaprolactone polyol and dimethylol alcohol in acetone to obtain a mixed solution; S102, add diisocyanate to the mixed solution and react until the reaction is complete; S103, add ethylene glycol to the reaction system of step S102, and continue the reaction until the reaction stops; S104, add triethylamine to the reaction mixture to neutralize, stir vigorously and add deionized water to emulsify, and finally remove the solvent acetone; The reaction molar ratio of polycaprolactone polyol, dimethylol polyol, diisocyanate, ethylene glycol and triethylamine is 2:3:10:1:3.

[0009] As a further optimization of the above scheme, in step S1, the water-soluble polyurethane emulsion and isopropanol are mixed at a volume ratio of 4:1, and the filter membrane used for filtration has a pore size of 50μm.

[0010] As a further optimization of the above solution, in step S2, the coating process is a blade coating process, the substrate is a glass substrate, the blade coating speed on the substrate is 30~50mm / s, and the working pressure of the nitrogen air knife is 0.7kgf / cm². 2 .

[0011] As a further optimization of the above scheme, in step S2, the heating temperature is 85℃, the holding time is 1h, and the cooling temperature is 0℃; the width of the formed random crack is 20~100μm.

[0012] As a further optimization of the above scheme, in step S3, the deposition process adopts magnetron sputtering, and the sputtering working vacuum is 0.75 Pa; the thickness of the Cu seed layer is 1~3 nm, and the thickness of the Ag metal layer is 5~7 nm.

[0013] As a further optimization of the above scheme, in step S3, the template layer generated by the film is removed by solvent dissolution, and the solvent for solvent dissolution is one of dimethylformamide or tetrahydrofuran.

[0014] The present invention also provides a method for leading out the electrodes for the above-mentioned electrochromic device, comprising the following steps: a) The substrate with the prepared electrode is cleaned using a nanosecond laser; b) Attach the busbar along the long side of the substrate, with half of the busbar attached to the electrode and the other half attached to the edge of the substrate, and then lead out the electrode.

[0015] As a further optimization of the above scheme, in step a), the edge clearing width is 2cm; the laser wavelength is 633nm, the laser power is 65%, and the frequency is 600kHz.

[0016] As a further optimization of the above scheme, in step b), the busbar is composed of an aluminum-tin alloy.

[0017] The present invention provides a method for preparing an electrode for an electrochromic device, which has the following advantages: 1. A method for fabricating an electrode for an electrochromic device according to the present invention. The present invention utilizes random cracks formed by the drying and cracking of a water-soluble polyurethane emulsion as a mask to deposit a Cu seed layer and an Ag metal layer. After removing the mask, a transparent electrode resembling a metal mesh is formed. Compared to traditional transparent conductive oxides such as ITO and FTO, the metal mesh, especially the Ag layer, has extremely high lateral conductivity, effectively solving the problem of uneven potential distribution in large-size electrochromic devices, significantly reducing the sheet resistance of the device, and thus greatly improving the response speed and color uniformity of the electrochromic device during the coloring and fading processes.

[0018] 2. A method for preparing an electrode for an electrochromic device according to the present invention. The present invention utilizes a polyurethane synthesis formulation with a molar ratio of 2:3:10:1:3, combined with the dilution effect of isopropanol, to control the rheological properties and surface tension of the precursor solution. By combining a coating, heating and drying, and cooling process, random cracks with controllable crack width and uniform density on the substrate surface can be induced. This results in a wide process window, stable crack morphology, and ensures the continuity and integrity of the subsequently deposited metal electrode, avoiding open circuit phenomena.

[0019] 3. A method for fabricating electrodes for an electrochromic device according to the present invention utilizes a metal mesh structure formed by random cracks. While ensuring high conductivity, most areas remain exposed glass substrates, thus exhibiting extremely high visible light transmittance. Furthermore, the random mesh structure effectively avoids moiré pattern optical interference. In addition, compared to brittle oxide conductive layers, the metal mesh structure possesses better mechanical flexibility and bending resistance, improving the mechanical stability of the device.

[0020] Specific embodiments of the present invention are disclosed in detail with reference to the following description and accompanying drawings, indicating how the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope as a result, and the embodiments of the present invention include many changes, modifications and equivalents. Attached Figure Description

[0021] Figure 1 This is a flowchart of an electrode for an electrochromic device prepared according to the present invention; Figure 2 This is a structural diagram of an electrode for an electrochromic device prepared according to the present invention; Figure 3 The visible light transmittance diagrams of the actual sample prepared in Example 1 of the present invention in both the colored and faded states are shown. Figure 4 This is a graph showing the change in visible light transmittance over time of the actual sample prepared in Example 1 of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0023] It should be noted that when an element is referred to as "set on" or "provided with" another element, it can be directly on the other element or there may be an intermediate element. When an element is referred to as "connected to" or "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time. "Fixed connection" means fixed connection. There are many ways of fixed connection, which are not within the scope of protection of this document. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this document are only for illustrative purposes and do not represent the only implementation method.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in the specification herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. like Figure 1 The diagram shows a flowchart of a method for preparing an electrode for an electrochromic device according to the present invention. Figure 2 The diagram shows the electrode and lead-out structure, including the glass substrate 1, the edge clearing area, the metal electrode, and the busbar.

[0025] Before fabricating the specific electrodes, a water-soluble polyurethane emulsion is first prepared as a precursor for the subsequent mask, following these steps: S1, Dissolve: Dissolve polycaprolactone polyol and dimethylol alcohol in analytical grade acetone to obtain a mixed solution; S2, polymerization: a certain amount of diisocyanate is added to the above mixed solution, and the reaction is carried out until the reaction is complete; S3, end-capping / chain extension, followed by the addition of ethylene glycol, and the reaction continues until the reaction stops; S4, neutralization and emulsification: Triethylamine is added to the reaction mixture for neutralization, followed by vigorous stirring and the addition of deionized water for emulsification. Finally, acetone is removed by vacuum distillation or other methods to obtain a water-soluble polyurethane emulsion.

[0026] In a preferred embodiment of the present invention, the molar ratio of polycaprolactone polyol: dimethylol polyol: diisocyanate: ethylene glycol: triethylamine is controlled to be 2:3:10:1:3.

[0027] Example 1: This embodiment provides a method for preparing and extracting electrodes for electrochromic devices, the specific steps of which are as follows: S1, Preparation of mask precursor solution: The water-soluble polyurethane emulsion and isopropanol prepared above are mixed at a volume ratio of 4:1, stirred thoroughly, and filtered using a filter membrane with a pore size of 50μm to remove impurities and bubbles, thus obtaining the mask precursor solution.

[0028] S2, Coating and Crack Induction: A coating process is used to deposit a film on a glass substrate. The doctor blade's movement speed on the substrate is controlled at 30 mm / s, and the nitrogen air knife's working pressure is 0.7 kgf / cm². 2 The wet film formed on the glass substrate is first heated to 85°C and kept at that temperature for 1 hour to dry it. Then it is taken out and rapidly cooled to 0°C, for example, by placing it in an ice water bath or a low-temperature environment for rapid cooling. Utilizing the principle of thermal expansion and contraction, randomly distributed cracks are formed on the surface of the film. According to the measurement, the width of the random cracks formed in this embodiment is about 100μm.

[0029] S3, Metal Layer Deposition: Place the glass with the cracked mask on its surface onto the magnetron sputtering sample stage, and mount the Cu and Ag targets onto their respective DC sputtering cathodes. Evacuate the base vacuum of the magnetron sputtering system to 6.0 × 10⁻⁶. -5 Pa, introduce 99.99% pure argon gas as sputtering gas, and adjust the working vacuum to 0.75 Pa.

[0030] First, turn on the Cu target and sputter at a power of 40W to deposit a 1nm thick Cu seed layer; Next, the Cu target was turned off, the Ag target was turned on, and the sputtering power was 50W to deposit a 7nm thick Ag metal layer. Finally, the template layer formed by the polyurethane film is removed by dissolving it with dimethylformamide solvent, while retaining the metal deposited at the cracks, thereby obtaining a mesh-like transparent electrode.

[0031] S4, Electrode Lead-out: The edges of the glass substrate with the prepared electrode layer are cleaned using a nanosecond laser, with a clean-out width of 2 cm. The laser process parameters are: wavelength 633 nm, laser power 65%, and frequency 600 kHz. A busbar composed of aluminum-tin alloy is attached along the long side of the substrate, with half of the busbar's width pressing on the metal electrode and the other half pressing on the cleaned insulating area, thus completing the electrode lead-out.

[0032] Combination Figure 3 and Figure 4 As shown, the electrode prepared in this embodiment was applied to an electrochromic device. Test results show that the maximum difference in visible light transmittance ΔT between the colored and faded states is 85.2%. Optical response time tests show that the optical response time in the colored state is 21 s, and the optical response time in the faded state is 173 s.

[0033] Example 2: This embodiment provides a method for preparing and extracting electrodes for electrochromic devices. The main difference from Embodiment 1 lies in the coating speed and deposition thickness. The specific steps are as follows: S1, first dissolve polycaprolactone polyol and dimethylol alcohol in acetone, then add a certain amount of diisocyanate until the reaction is complete, then add ethylene glycol until the reaction stops, finally add triethylamine to the reaction mixture for neutralization, stir vigorously and add deionized water for emulsification, remove the solvent acetone to obtain a water-soluble polyurethane emulsion. The molar ratio of the five reactants added above is 2:3:10:1:3, and the solvent acetone is analytical grade. S2. Water-soluble polyurethane emulsion and isopropanol were mixed at a volume ratio of 4:1 and stirred thoroughly. The mixture was then filtered through a 50 μm pore size filter to obtain the mask precursor solution. A blade coating process was used to deposit the film on a glass substrate. The blade moved at a speed of 40 mm / s on the substrate, and the nitrogen gas knife operated at a pressure of 0.7 kF / cm². 2 ; S3, the wet film formed on the glass substrate is first heated to 85°C, kept at that temperature for 1 hour, and then taken out and rapidly cooled to 0°C. Random cracks are formed on the surface of the film, and the crack width is 60μm. S4, place the glass with surface cracks onto the magnetron sputtering sample stage, and mount the Cu target and Ag target onto the corresponding DC sputtering cathodes, respectively. Then, evacuate the background vacuum of the magnetron sputtering system to 6.0 × 10⁻⁶. -5 Pa, 99.99% pure argon gas was introduced as sputtering gas, the working vacuum was adjusted to 0.75 Pa, the Cu target was turned on first, the sputtering power was 40 W, and a Cu seed layer thickness of 2 nm was obtained. Then the Cu target was turned off, the Ag target was turned on, the sputtering power was 50 W, and an Ag layer thickness of 6 nm was obtained. Finally, the template layer generated by the film was removed with dimethylformamide to obtain the electrode. S5, the glass with the prepared electrode layer is cleaned by a nanosecond laser to clean the edge of the substrate, with a cleaning width of 2cm; the laser wavelength is 633nm, the laser power is 65%, and the frequency is 600kHz. The busbar is attached along the long side of the substrate, with half of the busbar attached to the electrode and half attached to the cleaned edge, and the electrode is led out.

[0034] The electrode prepared in this embodiment was applied to an electrochromic device for testing. The results showed that the maximum difference in visible light transmittance ΔT between the colored and faded states was 84.9%. The optical response time in the colored state was 25 s, and the optical response time in the faded state was 178 s.

[0035] Example 3: This embodiment provides a method for preparing and extracting electrodes for electrochromic devices, further adjusting process parameters. The specific steps are as follows: S1, first dissolve polycaprolactone polyol and dimethylol alcohol in acetone, then add a certain amount of diisocyanate until the reaction is complete, then add ethylene glycol until the reaction stops, finally add triethylamine to the reaction mixture for neutralization, stir vigorously and add deionized water for emulsification, remove the solvent acetone to obtain a water-soluble polyurethane emulsion. The molar ratio of the five reactants added above is 2:3:10:1:3, and the solvent acetone is analytical grade. S2. Water-soluble polyurethane emulsion and isopropanol were mixed at a volume ratio of 4:1 and stirred thoroughly. The mixture was then filtered through a 50 μm pore size filter to obtain the mask precursor solution. A blade coating process was used to deposit the film on a glass substrate. The blade moved at a speed of 50 mm / s on the substrate, and the nitrogen gas knife operated at a pressure of 0.7 kAf / cm². 2 ; S3, the wet film formed on the glass substrate is first heated to 85°C and kept at that temperature for 1 hour. Then it is taken out and rapidly cooled to 0°C. Random cracks are formed on the surface of the film, and the crack width is 20μm. S4, place the glass with surface cracks onto the magnetron sputtering sample stage, and mount the Cu target and Ag target onto the corresponding DC sputtering cathodes, respectively. Then, evacuate the background vacuum of the magnetron sputtering system to 6.0 × 10⁻⁶. -5 Pa, 99.99% pure argon gas was introduced as sputtering gas, the working vacuum was adjusted to 0.75 Pa, the Cu target was turned on first, the sputtering power was 40 W, and a Cu seed layer thickness of 3 nm was obtained. Then the Cu target was turned off, the Ag target was turned on, the sputtering power was 50 W, and an Ag layer thickness of 5 nm was obtained. Finally, the template layer generated by the film was removed with dimethylformamide to obtain the electrode. S5, the glass with the prepared electrode layer is cleaned by a nanosecond laser to clean the edge of the substrate, with a cleaning width of 2cm; the laser wavelength is 633nm, the laser power is 65%, and the frequency is 600kHz. The busbar is attached along the long side of the substrate, with half of the busbar attached to the electrode and half attached to the cleaned edge, and the electrode is led out.

[0036] The electrode prepared in this embodiment was applied to an electrochromic device, and the visible light transmittance of the device in the colored and faded states was tested. The maximum difference ΔT between the visible light transmittance in the colored and faded states was 83.2%. Then, the optical response time of the device in the colored and faded states was tested. The optical response time in the colored state was 29s, and the optical response time in the faded state was 185s.

[0037] As can be seen from the above embodiments, the present invention utilizes the random cracks formed by the drying and cracking of water-soluble polyurethane emulsion as a mask. By adjusting the coating speed, the width of the cracks can be effectively controlled to be 20~100μm. The prepared Ag / Cu composite metal mesh electrode has excellent optical transmittance (ΔT>83%) and good conductivity. Combined with laser edge clearing and busbar semi-bonding processes, the node resistance is significantly reduced, resulting in a faster response speed for large-size electrochromic devices.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an electrode for an electrochromic device, characterized in that, Includes the following steps: S1, mix water-soluble polyurethane emulsion and isopropanol, stir until uniformly mixed and then filter to obtain mask precursor liquid; S2, the mask precursor liquid is coated to form a wet film on the upper surface of the substrate. It is first heated and kept at a temperature sufficient to dry the film layer. Then it is taken out and cooled to form random cracks on the surface of the film. S3, deposit a metal seed layer Cu and a metal layer Ag on the surface of the above thin film, and then remove the template layer generated by the thin film to obtain the electrode for electrochromic device.

2. The method for preparing an electrode for an electrochromic device according to claim 1, characterized in that: The preparation steps of the water-soluble polyurethane emulsion in step S1 are as follows: S101, dissolve polycaprolactone polyol and dimethylol alcohol in acetone to obtain a mixed solution; S102, add diisocyanate to the mixed solution and react until the reaction is complete; S103, add ethylene glycol to the reaction system of step S102, and continue the reaction until the reaction stops; S104, add triethylamine to the reaction mixture to neutralize, stir vigorously and add deionized water to emulsify, and finally remove the solvent acetone; The reaction molar ratio of polycaprolactone polyol, dimethylol polyol, diisocyanate, ethylene glycol and triethylamine is 2:3:10:1:

3.

3. The method for preparing an electrode for an electrochromic device according to claim 1, characterized in that: In step S1, water-soluble polyurethane emulsion and isopropanol are mixed at a volume ratio of 4:1, and the filter membrane used for filtration has a pore size of 50 μm.

4. The method for preparing an electrode for an electrochromic device according to claim 1, characterized in that: In step S2, the coating process is a blade coating process, the substrate is a glass substrate, the blade coating speed on the substrate is 30~50mm / s, and the working pressure of the nitrogen air knife is 0.7kgf / cm². 2 .

5. The method for preparing an electrode for an electrochromic device according to claim 1, characterized in that: In step S2, the heating temperature is 85℃, the holding time is 1h, and the cooling temperature is 0℃; the width of the formed random crack is 20~100μm.

6. The method for preparing an electrode for an electrochromic device according to claim 1, characterized in that: In step S3, the deposition process uses magnetron sputtering with a working vacuum of 0.75 Pa; the Cu seed layer has a thickness of 1-3 nm, and the Ag layer has a thickness of 5-7 nm.

7. The method for preparing an electrode for an electrochromic device according to claim 1, characterized in that: In step S3, the template layer generated by the film is removed by solvent dissolution, and the solvent for solvent dissolution is either dimethylformamide or tetrahydrofuran.

8. The method for drawing out the electrode for an electrochromic device according to any one of claims 1-7, characterized in that: Includes the following steps: a) The substrate with the prepared electrode is cleaned using a nanosecond laser; b) Attach the busbar along the long side of the substrate, with half of the busbar attached to the electrode and the other half attached to the edge of the substrate, and then lead out the electrode.

9. The extraction method according to claim 8, characterized in that: In step a), the edge clearing width is 2cm; the laser wavelength is 633nm, the laser power is 65%, and the frequency is 600kHz.

10. The extraction method according to claim 8, characterized in that: In step b), the busbar is composed of an aluminum-tin alloy.

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