Preparation method of directional micro-nano transparent electrode

Abstract

The invention discloses a method for manufacturing a directional micro-nano transparent electrode, which comprises the following steps of: (1) selecting a water-based crackle coating, adding deionized water, and uniformly mixing to obtain a cracking liquid; (2) coating the cracking liquid on the orientation induction template, and drying to form an orientation cracking template; and (3) depositing metal on the oriented cracking template, and removing the oriented cracking template to obtain the oriented micro-nano transparent electrode. According to the method, cracks are guided to extend in a fixed direction by utilizing longitudinal ordered arrangement of an orientation induction template such as surface molecules of a natural cellulose membrane, compared with traditional disordered cracks, the optical consistency of a metal grid is remarkably improved, and the problem of performance fluctuation in large-area preparation is solved; the method can also synergistically improve optical and electrical properties.

Description

Technical Field

[0001] This invention belongs to the field of metal network electrode technology, and specifically relates to a method for preparing a directional micro / nano transparent electrode. Background Technology

[0002] Metal mesh electrodes, as an important component of flexible transparent conductive materials, are widely used in devices such as photodetectors, solar cells, and touch panels. Currently, fabricating metal meshes based on the cracking phenomenon is a low-cost and simple process strategy. However, traditional cracking methods often suffer from problems such as random crack distribution and poor structural repeatability, which limit the stability and performance consistency of devices.

[0003] Existing technologies still have the following main problems in the application of large-area flexible devices:

[0004] Poor controllability of crack structure: Existing technologies rely on random stress or interfacial tension to induce cracking, and the direction, width and period of cracks are difficult to control precisely, resulting in poor uniformity of metal mesh; for example, in the cracking method of polymer thin film, the crack density deviation between adjacent regions can reach 30%, which seriously affects the consistency of device performance.

[0005] The bonding between the template and the metal layer is weak: Traditional cracked templates (such as polystyrene PS, SiO2) and metal coatings (Ag, Cu) are mostly physically adsorbed, resulting in insufficient interfacial adhesion. During the bending or friction process of flexible devices, the metal layer is prone to detachment, leading to a sharp drop in conductivity and a shortened service life (usually less than 1000 bending cycles).

[0006] Insufficient stability in large-area preparation: Environmental factors (temperature, humidity) have a significant impact on the cracking process. Under the same process parameters, the crack distribution of large-area substrates (>10 cm × 10 cm) is significantly different, and the yield of mass production is less than 50%, which is difficult to meet the needs of industrialization.

[0007] Balancing optical and electrical properties is difficult: disordered crack networks tend to exacerbate light scattering (transmittance < 83%). If conductivity is improved by increasing crack density, transmittance will decrease further. Conversely, sparse cracks have better transmittance but insufficient conductivity (sheet resistance > 20 Ω / □), making it difficult to achieve both high transmittance and high conductivity.

[0008] Environmental and cost issues related to materials: Some technologies use oily polymers or fluorinated sols as cracking precursors, resulting in high emissions of volatile organic compounds (VOCs) and difficulty in degrading the templates; at the same time, metal deposition processes such as magnetron sputtering are expensive, which is not conducive to low-cost large-scale production.

[0009] Therefore, there is an urgent need for a crack template preparation strategy that is structurally controllable, has uniform crack direction, and is easy to expand over a large area, so as to achieve the controllable preparation of high-performance metal mesh electrodes. Summary of the Invention

[0010] The purpose of this invention is to provide a method for preparing directional micro / nano transparent electrodes.

[0011] The above-mentioned objective of this invention can be achieved by the following technical solution: a method for manufacturing a directional micro / nano transparent electrode, comprising the following steps:

[0012] (1) Select water-based cracking coating, add deionized water and mix well to prepare cracking liquid;

[0013] (2) The cracking liquid obtained in step (1) is coated on the orientation induction template and dried to form an orientation cracking template;

[0014] (3) Deposit metal on the orientation crack template prepared in step (2), and then remove the orientation crack template to obtain the oriented micro-nano transparent electrode.

[0015] In the above-mentioned method for fabricating oriented micro / nano transparent electrodes:

[0016] Preferably, the volume ratio of the water-based crackle coating to the deionized water in step (1) is 100:0~40.

[0017] More preferably, the volume ratio of the water-based crackle coating to the deionized water in step (1) is 100:10~40.

[0018] Preferably, the water-based crackle coating is a water-based acrylic emulsion.

[0019] Preferably, in step (1), magnetic stirring is used when mixing, and the magnetic stirring time is 30~60 minutes.

[0020] Preferably, the orientation-inducing template in step (2) is a natural cellulose membrane.

[0021] Natural cellulose membranes can regulate crack orientation and distribution: by inducing cracks to propagate in an orderly manner along a specific direction through the oriented micro-nano structure of natural cellulose membranes, the problem of disordered cracks on large-area substrates can be solved, and the uniformity and controllability of metal mesh structures can be achieved.

[0022] Natural cellulose membranes can enhance the bonding force between the template and the metal layer: by utilizing the coordination effect between the hydroxyl groups on the surface of the cellulose membrane and the metal ions, the interfacial bonding between the cracked template and the metal coating can be strengthened, reducing metal detachment during bending or long-term use.

[0023] In fact, this invention achieves an ordered crack template structure through the natural orientation of the cellulose membrane, improving the disorder of traditional crack templates and obtaining an oriented and controllable metal network electrode crack template. However, the natural cellulose membrane in this invention is not unique. For example, similar effects can be achieved by performing micro-nano structure processing on substrate materials such as PET and glass.

[0024] Therefore, unlike the traditional cracking method that relies on random stress to form cracks in the existing technology, the present invention uses a natural cellulose membrane as an orientation-inducing template. The longitudinally ordered arrangement of cellulose molecules on its surface can guide the crack to propagate along the direction of minimum stress, which solves the problem of crack disorder from the root and realizes the directional controllability of the metal mesh structure, providing a structural basis for performance consistency.

[0025] More importantly, the orientation-induced template in this invention can strengthen the interfacial bonding between the template and the metal layer. For example, the hydroxyl groups on the surface of the cellulose membrane in this invention can form coordination with metal ions, which significantly enhances the interfacial adhesion between the cracked template and the metal coating. Compared with the weak physical bonding between the traditional template and the metal layer, this chemical action can effectively reduce metal detachment under bending, friction and other working conditions, and greatly improve the mechanical stability of the device.

[0026] Preferably, the coating in step (2) is a spin coating method, and the spin coating speed is 1500~2000r / s.

[0027] Preferably, the drying in step (2) is performed by heating with a heating table.

[0028] When using a heating table for drying, adjust the temperature of the heating table to 35~60℃ and the heating time to 5~10 minutes.

[0029] Preferably, the metal deposition method in step (3) is magnetron sputtering.

[0030] Preferably, the metal in step (3) is gold, silver or copper.

[0031] Preferably, in step (3), acetone solution is used to clean and remove the orientation crack template.

[0032] This invention uses water-based crackle paint (with water as a diluent and low VOC emissions) as the crack film material, combined with a biodegradable natural cellulose membrane, which is in line with the trend of green manufacturing. The dynamic hydrogen bond network formed by the natural cellulose membrane can be dissolved in a weakly alkaline solution (pH=9~10), realizing the non-destructive peeling and efficient recycling of the metal mesh (recovery rate>99%), solving the problem of metal resource waste in traditional technologies.

[0033] The method of this invention has the following innovative features:

[0034] (1) Utilizing orientation-induced templates such as natural cellulose membranes to induce ordered cracking

[0035] This invention uses orientation-induced template natural cellulose membrane (such as bamboo fiber membrane) as substrate. The longitudinally ordered arrangement of cellulose molecules on its surface can guide the cracked film material to expand along the molecular arrangement direction (the direction of minimum stress) during the drying process, forming an oriented crack network. This method fundamentally solves the problems of random crack distribution and poor structural repeatability in traditional cracking methods, and realizes the orientation controllability of metal mesh.

[0036] (2) Strengthen the interfacial bonding between the cracked template and the metal layer

[0037] The hydroxyl groups (-OH) on the surface of natural cellulose membranes can react with metal ions (such as Ag). + Cu 2+ This mechanism forms a coordination interaction, significantly enhancing interfacial adhesion compared to the physical adsorption between traditional templates (such as PS and SiO2) and metal layers. This effectively reduces metal shedding from flexible devices under bending, friction, and other conditions, improving the mechanical stability and lifespan of the electrodes.

[0038] (3) Achieving controllable fabrication and performance uniformity of large-area metal mesh electrodes

[0039] By standardizing process parameters (such as the mixing ratio of water-based crackle coating and deionized water, spin coating speed of 1500~2000 r / s, and drying temperature of 35~60℃), and combining the stabilizing orientation induction effect of cellulose membrane, this invention reduces the influence of environmental factors (humidity and temperature) on the cracking process, realizes the uniform preparation of metal mesh on large-area substrates, and solves the problems of large performance deviation and low yield in large-area production in traditional technologies.

[0040] (4) Select environmentally friendly materials and achieve efficient recycling of metal resources.

[0041] This invention uses water-based crackle coating (with water as a diluent and low VOC emissions) as the crack-film material, combined with a biodegradable natural cellulose membrane, which conforms to the trend of green manufacturing. At the same time, the dynamic hydrogen bond network formed by the modified cellulose membrane can be dissolved in a weakly alkaline solution (pH=9~10), realizing the non-destructive peeling and efficient recycling of the metal mesh (recovery rate>99%), solving the problem of metal resource waste in traditional technologies.

[0042] The present invention has the following advantages:

[0043] (1) Precisely control the crack structure and improve performance consistency: This invention utilizes the orientation-induced template, such as the longitudinally ordered arrangement of molecules on the surface of natural cellulose membrane, to guide the crack to expand along a fixed direction. Compared with traditional disordered cracking, the optical consistency of the metal mesh is significantly improved, solving the performance fluctuation problem in large-area preparation.

[0044] (2) Synergistic improvement of optical and electrical performance: The orientation crack network reduces light scattering loss and increases light transmittance to over 80% (550 nm); at the same time, the ordered metal mesh shortens the charge transport path and stabilizes the sheet resistance below 10 Ω / □, achieving synergistic optimization of high light transmittance (>80%) and high conductivity (<10 Ω / □) for the first time. Attached Figure Description

[0045] The present invention will now be further described with reference to the accompanying drawings and embodiments.

[0046] Figure 1 This is a flowchart of the spin coating method used to prepare oriented crack templates in Examples 1-5;

[0047] Figure 2 An optical microscope image of the oriented crack template prepared in Example 1;

[0048] Figure 3 An optical microscope image of the oriented crack template prepared in Example 2;

[0049] Figure 4 An optical microscope image of the oriented crack template prepared in Example 3;

[0050] Figure 5 An optical microscope image of the oriented crack template prepared in Example 4;

[0051] Figure 6 An optical microscope image of the oriented crack template prepared in Example 5;

[0052] Figure 7 The diagram shows the relationship between transparency and transmittance obtained by fitting the sample data from Examples 1-5, where samples 1-5 are from Examples 3, 2, 4, 5, and 1, respectively.

[0053] Figure 8 This is an optical microscope image of the oriented micro / nano transparent electrode prepared in Example 6. Detailed Implementation

[0054] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0055] Unless otherwise specified in the following implementation plan, the test conditions are generally as per standard test conditions or the test conditions recommended by the reagent company. Unless otherwise specified, all materials and reagents used are commercially available.

[0056] Unless otherwise specified, the terms used in the following implementation methods and embodiments generally have the meanings commonly understood by those skilled in the art.

[0057] Preparations for using orientation-inducing templates include, but are not limited to, the following:

[0058] Cleaning glass: Wipe the front and back of the glass with isopropyl alcohol and heat to dry, then clean with an ultrasonic cleaner;

[0059] Cleaning the flexible substrate: First, cut the cellulose membrane to the size of glass. Then, wet the natural cellulose membrane. Next, use the membrane for ultrasonic cleaning and remove it for later use.

[0060] Applying the membrane: Use transparent tape to adhere the cellulose membrane to the glass surface and then perform water absorption treatment.

[0061] The recommended, but not limited to, methods for preparing natural cellulose membranes are as follows: Efficient fabrication of anisotropic regenerated cellulose films from bamboo via a facile wet extrusion strategy, Xinghuan Lin, International Journal of Biological Macromolecules, International Journal of Biological Macromolecules 265 (2024) 130966.

[0062] Example 1

[0063] The method for fabricating oriented micro / nano transparent electrodes provided in this embodiment includes the following steps:

[0064] (1) Mix aqueous acrylic emulsion and deionized water at a volume ratio of 100:10 (mass ratio) and stir magnetically for 30 minutes to prepare a cracking solution;

[0065] (2) Using a spin coater, 500 mL of cracking solution was added dropwise at a speed of 1500 r / s and an acceleration of 500 r / s. The solution was then spin-coated for 20 seconds and evenly spread on the natural cellulose membrane. The membrane was then dried at 35°C for 5 minutes to form an oriented cracking template. The flowchart for preparing the oriented cracking template is shown below. Figure 1As shown, an optical microscope image of the prepared oriented crack template is as follows: Figure 2 As shown;

[0066] (3) Magnetron sputtering of metallic silver onto the orientation crack template prepared in step (2), and then washing with acetone solution to remove the orientation crack template (sacrificial layer, the same below) to obtain an orientation micro-nano transparent electrode (metal network electrode, the same below).

[0067] Example 2

[0068] The method for fabricating oriented micro / nano transparent electrodes provided in this embodiment includes the following steps:

[0069] (1) Mix aqueous acrylic emulsion and deionized water at a volume ratio of 100:10 and stir magnetically for 30 minutes to prepare a cracking solution;

[0070] (2) Using a spin coater, 500 mL of cracking solution was added dropwise at a speed of 2000 r / s and an acceleration of 500 r / s. The solution was then spin-coated for 20 s and evenly spread on the natural cellulose membrane. The membrane was then dried at 35°C for 5 minutes to form an oriented cracking template. The flowchart for preparing the oriented cracking template is shown below. Figure 1 As shown, an optical microscope image of the prepared oriented crack template is as follows: Figure 3 As shown;

[0071] (3) Magnetron sputtering of metallic silver onto the orientation crack template prepared in step (2), and then cleaning with acetone solution to remove the orientation crack template, thereby obtaining a directional micro / nano transparent electrode.

[0072] Example 3

[0073] The method for fabricating oriented micro / nano transparent electrodes provided in this embodiment includes the following steps:

[0074] (1) Mix aqueous acrylic emulsion and deionized water at a volume ratio of 100:10 and stir magnetically for 30 minutes to prepare a cracking solution;

[0075] (2) Using a spin coater, 500 mL of cracking solution was added dropwise at a speed of 2500 r / s and an acceleration of 500 r / s. The solution was then spin-coated for 20 s and evenly spread onto the natural cellulose membrane. The membrane was then dried at 35°C for 5 minutes to form an oriented cracking template. The flowchart for preparing the oriented cracking template is shown below. Figure 1 As shown, an optical microscope image of the prepared oriented crack template is as follows: Figure 4 As shown;

[0076] (3) Magnetron sputtering of metallic silver onto the orientation crack template prepared in step (2), and then cleaning with acetone solution to remove the orientation crack template, thereby obtaining a directional micro / nano transparent electrode.

[0077] From the above embodiments 1 to 3 Figures 2-4The results show that, under different rotation speeds during spin coating, the width of the crack lines and the width of the cracks in the crack template decrease with increasing rotation speed. The basic principle is that as the rotation speed increases, the crack solution becomes thinner on the cellulose membrane, and thus the thickness of the crack template becomes thinner after drying, resulting in smaller widths of the cracks and the width of the cracks.

[0078] The transmittance (GB / T26813—2011) and sheet resistance (GB / T 26074-2010) of the oriented micro-nano transparent electrodes prepared by sputtering metallic silver using the oriented crack templates of Examples 1-3 are shown in Table 1 below.

[0079] Table 1. Transmittance and sheet resistance of the directional micro / nano transparent electrodes in Examples 1-3

[0080] sample Light transmittance (%) Shear resistance (Ω / □) Example 1 82.5 5.4 Example 2 81.2 3.5 Example 3 80.4 2.4

[0081] Example 4

[0082] The method for fabricating oriented micro / nano transparent electrodes provided in this embodiment includes the following steps:

[0083] (1) Mix aqueous acrylic emulsion and deionized water at a volume ratio of 100:10 and stir magnetically for 30 minutes to prepare a cracking solution;

[0084] (2) Using a spin coater, 600 mL of cracking solution was added dropwise at a speed of 2000 r / s and an acceleration of 500 r / s. The solution was then spin-coated for 20 s and evenly spread on the natural cellulose membrane. The membrane was then dried at 35°C for 5 minutes to form an oriented cracking template. The flowchart for preparing the oriented cracking template is shown below. Figure 1 As shown, an optical microscope image of the prepared oriented crack template is as follows: Figure 5 As shown;

[0085] (3) Magnetron sputtering of metallic silver onto the orientation crack template prepared in step (2), and then cleaning with acetone solution to remove the orientation crack template, thereby obtaining a directional micro / nano transparent electrode.

[0086] Example 5

[0087] The method for fabricating oriented micro / nano transparent electrodes provided in this embodiment includes the following steps:

[0088] (1) Mix aqueous acrylic emulsion and deionized water at a volume ratio of 100:10 and stir magnetically for 30 minutes to prepare a cracking solution;

[0089] (2) Using a spin coater, 700 mL of cracking solution was added dropwise at a speed of 2000 r / s and an acceleration of 500 r / s. The solution was then spin-coated for 20 s and evenly spread on the natural cellulose membrane. After drying at 35°C for 5 minutes, an oriented cracking template was formed. The flowchart for preparing the oriented cracking template is shown below. Figure 1As shown, an optical microscope image of the prepared oriented crack template is as follows: Figure 6 As shown;

[0090] (3) Magnetron sputtering of metallic silver onto the orientation crack template prepared in step (2), and then cleaning with acetone solution to remove the orientation crack template, thereby obtaining a directional micro / nano transparent electrode.

[0091] From the above embodiments 2, 4, 5 and... Figure 3 , 5 As can be seen from the results in section 6, under different solution amounts added during spin coating, the width of the crack lines and the width of the cracks in the crack template increase with the increase of the amount of cracking solution added. The basic principle is that as the amount of cracking solution increases, the cracking solution becomes thicker on the cellulose membrane, and thus the thickness of the crack template will be thicker after drying, resulting in a larger width of the crack template and a larger width of the crack lines.

[0092] Directional micro / nano transparent electrodes were prepared by sputtering metallic silver using the oriented crack templates of Examples 2, 4, and 5. The transmittance and sheet resistance are shown in Table 2 below.

[0093] Table 2. Transmittance and sheet resistance of directional micro / nano transparent electrodes in Examples 2, 4, and 5.

[0094] sample Light transmittance (%) Shear resistance (Ω / □) Example 2 81.2 3.5 Example 4 81.8 4.8 Example 5 82.3 5.3

[0095] The relationship between transparency and transmittance obtained by fitting the sample data obtained in Examples 1-5 is as follows: Figure 7 As shown.

[0096] Example 6

[0097] The method for fabricating oriented micro / nano transparent electrodes provided in this embodiment includes the following steps:

[0098] (1) Mix aqueous acrylic emulsion and deionized water at a volume ratio of 100:10 (mass ratio) and stir magnetically for 30 minutes to prepare a cracking solution;

[0099] (2) Using a spin coater, 700 mL of cracking solution was added dropwise at a speed of 2000 r / s and an acceleration of 500 r / s. The solution was then spin-coated for 20 s and evenly spread on the natural cellulose membrane. After drying at 35°C for 5 minutes, an oriented cracking template was formed. The flowchart for preparing the oriented cracking template is shown below. Figure 1 As shown;

[0100] (3) Magnetron sputtering of metallic silver onto the oriented crack template prepared in step (2), followed by washing with acetone solution to remove the oriented crack template, yielding a directional micro / nano transparent electrode. An optical microscope image of the prepared directional micro / nano transparent electrode is shown below. Figure 8 As shown.

[0101] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for fabricating a directional micro / nano transparent electrode, characterized in that, Includes the following steps: (1) Select water-based cracking coating, add deionized water and mix well to prepare cracking liquid; (2) The cracking liquid obtained in step (1) is coated on the orientation induction template and dried to form an orientation cracking template; (3) Deposit metal on the orientation crack template prepared in step (2), and then remove the orientation crack template to obtain the oriented micro-nano transparent electrode.

2. The method for fabricating a directional micro / nano transparent electrode according to claim 1, characterized in that, The volume ratio of the water-based crackle coating to the deionized water in step (1) is 100:0~40, and the water-based crackle coating is a water-based acrylic emulsion.

3. The method for fabricating a directional micro / nano transparent electrode according to claim 1, characterized in that, The orientation-inducing template mentioned in step (2) is a natural cellulose membrane.

4. The method for fabricating a directional micro / nano transparent electrode according to claim 1, characterized in that, The coating method described in step (2) is spin coating. During spin coating, the spin coating speed is 1500~2000r / s.

5. The method for fabricating a directional micro / nano transparent electrode according to claim 1, characterized in that, The drying process described in step (2) involves heating and drying using a heating table.

6. The method for fabricating a directional micro / nano transparent electrode according to claim 5, characterized in that, When using a heating table for drying, adjust the temperature of the heating table to 35~60℃ and the heating time to 5~10 minutes.

7. The method for fabricating a directional micro / nano transparent electrode according to claim 1, characterized in that, In step (3), the metal is deposited by magnetron sputtering.

8. The method for fabricating a directional micro / nano transparent electrode according to claim 1, characterized in that, In step (3), acetone solution is used to clean and remove the orientation crack template.

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