A transparent conductive film with a double-layer grid structure and a preparation method thereof

Abstract

The present invention provides a transparent conductive film with a double-layer grid structure and a preparation method thereof, relating to the field of transparent conductive films. The preparation method of the transparent conductive film comprises the following steps: first, a copper film is formed on the surface of a transparent flexible substrate using vacuum coating technology; then, a self-cracking film is formed on the surface of the copper film using a self-cracking agent, and the self-cracking film naturally cracks to form a grid-like cracking template; then, a BaSnO3 film is formed on the grid-like cracking template using magnetron sputtering technology, and the self-cracking film on the copper film is removed to obtain a BaSnO3 grid; finally, an etching solution is sprayed on the surface of the BaSnO3 grid to etch the copper film into a copper grid, thereby obtaining a transparent conductive film with a double-layer grid structure. The present invention combines the high conductivity of the copper grid with the high permeability of the BaSnO3 grid to produce a high-performance transparent conductive film with a low overall preparation cost. The product has good applications in transparent conductive components, flexible transparent heaters, flexible displays, functional inorganic coatings, and other fields.

Description

Technical Field

[0001] The present invention relates to the field of transparent conductive films, in particular to a transparent conductive film containing a double-layer grid structure and a preparation method thereof. Background Art

[0002] Transparent conductive films are those with a transmittance greater than 80% and a film resistance less than 15Ω / sq in the visible light wavelength range of 380-800nm. With the rapid advancement of science and technology and the ever-improving quality of life, applications such as new display devices, high-power solar cells, large-scale outdoor displays, and energy-saving infrared reflective films are becoming increasingly widespread, driving a growing demand for transparent conductive films. Currently, the most widely used transparent conductive film in the market is Sn-doped In2O3, or ITO film. ITO film boasts excellent optoelectronic properties and has long dominated the market as a transparent conductive film in optoelectronic device applications. However, the carrier concentration of ITO films has essentially reached its limit, and high carrier concentrations can reduce optical properties such as transmittance. Furthermore, indium has issues such as high toxicity, high cost, low stability, and susceptibility to degradation. Therefore, there is an urgent need to develop new transparent conductive films that not only maintain or exceed the optoelectronic performance of ITO but also offer lower cost and higher stability.

[0003] BaSnO3 has a low electron effective mass, and the Hall mobility of BaSnO3-based films is higher than that of ITO films. This results in higher field-effect mobility and higher electrical conductivity. Furthermore, BaSnO3-based films have a lower oxygen chemical diffusion coefficient and better thermal stability than ITO films, maintaining excellent photoelectric properties even in air over long periods of time. Compared to the strategic In2O3 material, Ba and Sn are abundant, allowing for long-term application.

[0004] Based on this, how to prepare BaSnO3-based thin films with excellent performance has become the focus of research by scholars at home and abroad. Summary of the Invention

[0005] In order to address the deficiencies in the prior art, the present invention provides a transparent conductive film containing a double-layer grid structure and a preparation method thereof. The high conductivity of the copper grid and the high permeability of the BaSnO3 grid are combined by magnetron sputtering technology to produce a high-performance transparent conductive film with low overall preparation cost. The product has good applications in transparent conductive components, transparent flexible heaters, flexible displays, functional inorganic coatings and other fields.

[0006] In order to achieve the above object, the specific scheme adopted by the present invention is:

[0007] In one aspect, the present invention discloses a method for preparing a transparent conductive film having a double-layer grid structure, comprising the following steps:

[0008] Step 1: Clean the transparent flexible substrate, and after the transparent flexible substrate is dried, form a copper film on the surface of the transparent flexible substrate using a vacuum coating technology;

[0009] Step 2: using a self-cracking agent to prepare a self-cracking film on the surface of the copper film, drying it at room temperature to 80°C, so that the self-cracking film naturally cracks to form a network cracking template;

[0010] Step 3: Using magnetron sputtering technology to prepare a BaSnO3 thin film on the mesh crack template;

[0011] Step 4: Use acetone and ultrasonic cleaning to remove the self-cracking film on the copper film to obtain a BaSnO3 grid;

[0012] Step 5: Spray etching solution onto the surface of the BaSnO3 grid and seal it and let it stand to etch the copper film into a copper grid, thereby obtaining a transparent conductive film with a double-layer grid structure.

[0013] Furthermore, in step 1, the transparent flexible substrate is a flexible glass or transparent flexible plastic with a thickness of 30-120 μm.

[0014] Furthermore, in step one, the vacuum coating technology is magnetron sputtering coating, thermal evaporation coating or pulsed laser deposition.

[0015] Furthermore, in step 2, the self-cracking agent is any one of pure acrylic emulsion, silicone acrylic emulsion, acrylic acid emulsion or nail polish.

[0016] Furthermore, in step 2, the thickness of the self-cracking film is 5-15 μm.

[0017] Furthermore, in step 2, a self-cleaving film is prepared by a Czochralski coating method or a spin coating method.

[0018] Furthermore, in step three, a BaSnO3 thin film is prepared on the mesh cracking template and the outer peripheral surface of the copper film using magnetron sputtering technology.

[0019] Furthermore, in step five, the etching solution is evenly sprayed onto the surface of the BaSnO3 grid and sealed and allowed to stand for 2 to 10 minutes. The etching solution used is a FeCl3 solution with a concentration of 10 to 40%, and the etching temperature is controlled to be 40 to 60°C. After the etching is completed, it is cleaned with deionized water and alcohol to remove the etching solution.

[0020] On the other hand, the present invention discloses a transparent conductive film containing a double-layer grid structure, including a transparent flexible substrate and a double-layer grid structure arranged on the transparent flexible substrate, wherein the double-layer grid structure is composed of a composite of a copper grid and a BaSnO3 grid, and the BaSnO3 grid covers the top surface of the copper grid.

[0021] Furthermore, the thickness of the copper grid is 100-200 nm, and the thickness of the BaSnO 3 grid is 50-200 nm.

[0022] Beneficial effects:

[0023] (1) When preparing a transparent conductive film, the present invention first uses vacuum coating technology to deposit a dense copper film on the surface of a transparent flexible substrate; then a self-cracking film is prepared on the surface of the copper film, and the self-cracking film naturally cracks to form a mesh-like cracking template; then a BaSnO3 film is prepared on the mesh-like cracking template, and the self-cracking film is removed to obtain a continuous BaSnO3 grid. Finally, an etching solution is sprayed on the surface of the BaSnO3 grid, and the grid is sealed and left to stand for a period of time to etch the copper film into a copper grid, thereby obtaining a transparent conductive film with a double-layer grid structure. The transparent conductive film of the present invention is formed by forming a copper grid and a BaSnO3 grid on the surface of a transparent flexible substrate, wherein the copper grid has good density and good conductivity, and the bottom surface of the copper grid is covered by the transparent flexible substrate and the top surface is covered by the BaSnO3 grid, so that the copper grid is not easily oxidized, and intermolecular connections are formed between the film layers of the transparent conductive film, so that the transparent conductive film has excellent photoelectric properties and stability.

[0024] (2) The present invention uses a self-cracking agent to prepare a self-cracking film on the surface of a copper film, and dries it at a temperature between room temperature and 80°C, so that the self-cracking film naturally cracks to form a network-like cracking template, which has the following advantages: (I) In the prior art (such as patent CN104993057B), the preparation process of the cracking agent is relatively complicated. However, the self-cracking agent of the present invention directly uses any one of pure acrylic emulsion, silicone acrylic emulsion, acrylic emulsion or nail polish, without the need for a tedious preparation process, greatly simplifying the operation process and improving work efficiency. (II) In the prior art, the cracking of the cracking film requires the control of specific temperature, humidity and time conditions. The precise control of these conditions increases the complexity and time cost of the operation. However, the self-cracking film of the present invention can achieve natural cracking in a wide temperature range from room temperature to 80°C, without the need for strict control of environmental conditions, thereby improving the cracking efficiency.

[0025] (3) In order to further improve the performance of the transparent conductive film of the present invention, when preparing the BaSnO3 film, in addition to preparing the BaSnO3 film on the mesh crack template, the present invention also prepares a BaSnO3 film on the peripheral surface of the copper film. This can prevent the peripheral surface of the copper grid from being oxidized, thereby making the performance of the transparent conductive film better.

[0026] (4) The present invention uses an etching solution to treat the copper film to prepare a copper grid, which has the following advantages: (I) The main component of the etching solution is a FeCl3 solution with a concentration of 10-40%, which can effectively and selectively react with unwanted copper without chemically reacting with the transparent flexible substrate and the BaSnO3 grid. This high selectivity ensures the accuracy of the etching process and avoids damage to materials other than the target structure, thereby ensuring the quality and performance of the final product. (II) By adjusting the concentration of FeCl3 in the etching solution, the etching rate of copper can be easily controlled. The higher the concentration, the faster the etching rate, which greatly facilitates time management and efficiency improvement in the production process. This controllability allows manufacturers to quickly adjust process parameters according to specific needs to meet the requirements of different application scenarios. (III) The etching process only requires spraying the etching solution evenly on the surface of the BaSnO3 grid and sealing it for 2-10 minutes, without the need for complex equipment or steps. In addition, after etching, the etching solution can be removed by washing with deionized water and alcohol. These cleaning materials are easy to obtain and harmless to the environment, meeting the requirements of green production. (IV) The etching process is carried out within a temperature range of 40–60°C, which is neither too high to cause thermal damage to the material nor too low to affect etching efficiency. This temperature adaptability makes the etching process more flexible and adaptable to different production environments and conditions. (V) Due to the high precision and controllability of the etching process, the resulting transparent conductive film with a double-layer grid structure exhibits excellent performance. This film not only maintains the original properties of the BaSnO3 grid but also achieves improved light transmittance by removing excess copper, making it suitable for a variety of electronic devices and optical applications.

[0027] (5) The transparent conductive film product prepared by the present invention has high reliability and low cost, is suitable for industrial production, and is particularly suitable for use in transparent conductive devices, transparent flexible heaters, flexible displays, and functional inorganic coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic cross-sectional view of the transparent conductive film prepared by the present invention.

[0029] Figure 2 This is a surface structure diagram of the transparent conductive film prepared in Example 1. DETAILED DESCRIPTION

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] The present invention provides a transparent conductive film with a double-layer grid structure and a preparation method thereof. Figure 1 The transparent conductive film includes a transparent flexible substrate and a double-layer grid structure provided on the transparent flexible substrate. The double-layer grid structure is composed of a copper grid and a BaSnO3 grid. The bottom copper grid provides a conductive path for the BaSnO3 grid. The copper grid prepared using vacuum coating technology has good density. The bottom surface of the copper grid is covered by the transparent flexible substrate, and the top surface is covered by the BaSnO3 grid. The copper grid is not easily oxidized. Intermolecular connections are formed between the layers of the transparent conductive film, and the transparent conductive film has excellent stability. Overall, the transparent conductive film is low in cost, has a dense structure, and stable performance. Its preparation method mainly includes the following steps:

[0032] Step 1: Clean the transparent flexible substrate with alcohol, acetone, or the like. After the transparent flexible substrate is dried, a copper film with a thickness of 100 to 200 nm is prepared on the surface of the transparent flexible substrate using a vacuum coating technique. Directly coating the copper film on the surface of the transparent flexible substrate facilitates the formation of intermolecular connections between the copper film and the transparent flexible substrate, which can significantly enhance the conductivity and reliability of the transparent conductive film. The transparent flexible substrate can be a material such as flexible glass or transparent flexible plastic, and the vacuum coating technique can be a coating scheme such as magnetron sputtering coating, thermal evaporation coating, or pulsed laser deposition.

[0033] Step 2: After step 1 is completed, a 5-15 μm thick self-cracking film is prepared on the surface of the copper film using a self-cracking agent, and the film is dried at a temperature between room temperature and 80°C to allow the self-cracking film to naturally crack and form a network-like cracking template. The self-cracking film is selected to obtain a network-like cracking template to facilitate the subsequent preparation of the copper grid and BaSnO3 grid. The use of any one of pure acrylic emulsion, silicone acrylic emulsion, acrylic emulsion, or nail polish as the self-cracking agent has the advantages of simple process and easy operation. The self-cracking film can be prepared by liquid phase coating methods such as pull-up coating and spin coating.

[0034] Step 3: Using magnetron sputtering technology, a BaSnO3 film with a thickness of 50-200 nm is prepared on the mesh cracking template and the outer surface of the copper film;

[0035] Step 4: Use acetone and ultrasonic cleaning to remove the self-cracking film on the copper film, thereby obtaining a BaSnO3 grid; the formed BaSnO3 grid is coated on the surface of the copper grid, so that only the inner wall of each grid inside the copper grid is exposed. However, since the thickness of the copper grid is very thin, not exceeding 200 nm, the total exposed area of ​​the copper grid is small, which can greatly reduce the contact area between the copper grid and the outside air, thereby ensuring that the copper grid is not easily oxidized, and at the same time, it can also improve the conductivity and transmittance of the transparent conductive film to a certain extent;

[0036] Step 5. Evenly spray the etching solution onto the surface of the BaSnO3 grid and seal it for 2 to 10 minutes. The etching solution mainly reacts with unnecessary copper and does not react with the transparent flexible substrate and the BaSnO3 grid. The etching solution used is a FeCl3 solution with a concentration of 10 to 40%. The higher the concentration of FeCl3 in the etching solution, the faster the copper etching speed. The etching temperature is controlled at 40 to 60 ° C. After etching, it is washed with deionized water and alcohol to remove the etching solution to obtain a transparent conductive film with a double-layer grid structure.

[0037] It should be noted that the transmittance and resistance of transparent conductive films can be regulated by the following methods: (1) Regulating the thickness of the copper film: the thicker the copper film, the better the conductivity of the transparent conductive film, but its transmittance and stability will decrease; (2) Regulating the thickness of the BaSnO3 film: the thicker the BaSnO3 film, the lower the transmittance of the transparent conductive film; (3) Regulating the thickness of the self-cracking film: the thicker the self-cracking film, the smaller the crack grid density, and the BaSnO3 grid density will also decrease in the later stage, and the transmittance and resistance will decrease accordingly.

[0038] The technical solution of the present invention is further described below with reference to specific embodiments and comparative examples.

[0039] Example 1

[0040] A method for preparing a transparent conductive film having a double-layer grid structure mainly comprises the following steps:

[0041] Step 1: Clean the transparent flexible substrate (flexible glass) with alcohol. After the transparent flexible substrate is dried, a copper film is prepared on the surface of the transparent flexible substrate by magnetron sputtering coating. When performing magnetron sputtering coating, the background vacuum of the magnetron sputtering system is pumped to 1.0×10 -3 Pa, high-purity (99.999%) argon gas was introduced, the pressure was adjusted to 1.0 Pa, the distance between the target and the substrate was fixed at 10 cm, the sputtering power was 100 W, and the metal copper target was sputtered to deposit a 200 nm thick copper film;

[0042] Step 2: Using an acrylic emulsion as a self-cracking agent, a 15 μm thick self-cracking film is prepared on the surface of the copper film by a pull-up coating method. The film is dried at 80°C to allow the self-cracking film to naturally crack and form a mesh-like cracking template. The pulling speed is 5 cm / min. The average mesh diameter of the cracks in the mesh-like cracking template is 100 μm, and the crack grid line width is 5-8 μm.

[0043] Step 3: Place the semi-finished product obtained in step 2 on the sample stage of the magnetron sputtering system and pump the background vacuum of the magnetron sputtering system to 1.0×10 -3Pa, high-purity (99.999%) argon gas was introduced, the pressure was adjusted to 1.0 Pa, the distance between the target and the substrate was fixed at 10 cm, the sputtering power was 100 W, and the ceramic BaSnO3 target was sputtered to deposit a 200 nm thick BaSnO3 film at room temperature;

[0044] Step 4: Use acetone and ultrasonic cleaning to remove the self-cracking film on the copper film. After cleaning, a BaSnO3 grid can be obtained;

[0045] Step 5: Evenly spray the etching solution onto the surface of the BaSnO3 grid and seal it for 2 minutes. The etching solution used is a 40% FeCl3 solution. The etching temperature is controlled at 60°C. After etching, it is washed with deionized water and alcohol to remove the etching solution to obtain a transparent conductive film with a double-layer grid structure.

[0046] refer to Figure 2 It can be seen that in the transparent conductive film prepared in this embodiment, the line width of the BaSnO3 grid is relatively uniform and has good continuity.

[0047] Example 2

[0048] A method for preparing a transparent conductive film having a double-layer grid structure mainly comprises the following steps:

[0049] Step 1: Clean the transparent flexible substrate (flexible glass) with acetone. After the transparent flexible substrate is dried, a copper film is prepared on the surface of the transparent flexible substrate by magnetron sputtering. When performing magnetron sputtering, the background vacuum of the magnetron sputtering system is pumped to 1.0×10 -3 Pa, high-purity (99.999%) argon gas was introduced, the pressure was adjusted to 1.0 Pa, the distance between the target and the substrate was fixed at 10 cm, the sputtering power was 100 W, and the metal copper target was sputtered to deposit a 150 nm thick copper film;

[0050] Step 2: Using nail polish as a self-cracking agent, a self-cracking film with a thickness of 8 μm is prepared on the surface of the copper film by a pull-up coating method. The film is dried at 40°C to allow the self-cracking film to naturally crack and form a mesh-like cracking template. The pulling speed is 11 cm / min. The average mesh diameter of the cracks in the mesh-like cracking template is 80 μm, and the crack grid line width is 6-10 μm.

[0051] Step 3: Place the semi-finished product obtained in step 2 on the sample stage of the magnetron sputtering system and pump the background vacuum of the magnetron sputtering system to 1.0×10 -3Pa, high-purity (99.999%) argon gas was introduced, the pressure was adjusted to 1.0 Pa, the distance between the target and the substrate was fixed at 10 cm, the sputtering power was 100 W, and the ceramic BaSnO3 target was sputtered to obtain a 150 nm thick BaSnO3 film at room temperature;

[0052] Step 4: Use acetone and ultrasonic cleaning to remove the self-cracking film on the copper film. After cleaning, a BaSnO3 grid can be obtained;

[0053] Step 5: Evenly spray the etching solution onto the surface of the BaSnO3 grid and seal it for 5 minutes. The etching solution used is a 20% FeCl3 solution. The etching temperature is controlled at 50°C. After etching, it is washed with deionized water and alcohol to remove the etching solution to obtain a transparent conductive film with a double-layer grid structure.

[0054] Example 3

[0055] A method for preparing a transparent conductive film having a double-layer grid structure mainly comprises the following steps:

[0056] Step 1: Clean the transparent flexible substrate (transparent flexible plastic) with alcohol. After the transparent flexible substrate is dried, a copper film is prepared on the surface of the transparent flexible substrate by magnetron sputtering coating. When performing magnetron sputtering coating, the background vacuum of the magnetron sputtering system is pumped to 1.0×10 -3 Pa, high-purity (99.999%) argon gas was introduced, the pressure was adjusted to 1.0 Pa, the distance between the target and the substrate was fixed at 10 cm, the sputtering power was 100 W, and the metal copper target was sputtered to deposit a 120 nm thick copper film;

[0057] Step 2: Using nail polish as a self-cracking agent, a 12 μm thick self-cracking film is prepared on the surface of the copper film by a pull-up coating method. The film is dried at 50°C to allow the self-cracking film to naturally crack and form a mesh-like cracking template. The pulling speed is 8 cm / min. The average mesh diameter of the cracks in the mesh-like cracking template is 90 μm, and the crack grid line width is 6-12 μm.

[0058] Step 3: Place the semi-finished product obtained in step 2 on the sample stage of the magnetron sputtering system and pump the background vacuum of the magnetron sputtering system to 1.0×10 -3 Pa, high-purity (99.999%) argon gas was introduced, the pressure was adjusted to 1.0 Pa, the distance between the target and the substrate was fixed at 10 cm, the sputtering power was 100 W, and the ceramic BaSnO3 target was sputtered to obtain a 120 nm thick BaSnO3 film at room temperature;

[0059] Step 4: Use acetone and ultrasonic cleaning to remove the self-cracking film on the copper film. After cleaning, a BaSnO3 grid can be obtained;

[0060] Step 5: Evenly spray the etching solution onto the surface of the BaSnO3 grid and seal it for 10 minutes. The etching solution used is a 10% FeCl3 solution. The etching temperature is controlled at 40°C. After etching, it is washed with deionized water and alcohol to remove the etching solution to obtain a transparent conductive film with a double-layer grid structure.

[0061] Example 4

[0062] A method for preparing a transparent conductive film having a double-layer grid structure mainly comprises the following steps:

[0063] Step 1: Clean the transparent flexible substrate (transparent flexible plastic) with acetone. After the transparent flexible substrate is dried, a copper film is prepared on the surface of the transparent flexible substrate by magnetron sputtering coating. When performing magnetron sputtering coating, the background vacuum of the magnetron sputtering system is pumped to 1.0×10 -3 Pa, high-purity (99.999%) argon gas was introduced, the pressure was adjusted to 1.0 Pa, the distance between the target and the substrate was fixed at 10 cm, the sputtering power was 100 W, and the metal copper target was sputtered to deposit a 100 nm thick copper film;

[0064] Step 2: Using an acrylic emulsion as a self-cracking agent, a 5 μm thick self-cracking film is prepared on the surface of the copper film by a pull-up coating method. The film is dried at 60°C to allow the self-cracking film to naturally crack to form a mesh-like cracking template. The pulling speed is 15 cm / min. The average mesh diameter of the cracks in the mesh-like cracking template is 60 μm, and the crack grid line width is 4-7 μm.

[0065] Step 3: Place the semi-finished product obtained in step 2 on the sample stage of the magnetron sputtering system and pump the background vacuum of the magnetron sputtering system to 1.0×10 -3 Pa, high-purity (99.999%) argon gas was introduced, the pressure was adjusted to 1.0 Pa, the distance between the target and the substrate was fixed at 10 cm, the sputtering power was 100 W, and the ceramic BaSnO3 target was sputtered to obtain a 100 nm thick BaSnO3 film at room temperature;

[0066] Step 4: Use acetone and ultrasonic cleaning to remove the self-cracking film on the copper film. After cleaning, a BaSnO3 grid can be obtained;

[0067] Step 5: Evenly spray the etching solution onto the surface of the BaSnO3 grid and seal it for 8 minutes. The etching solution used is a 25% FeCl3 solution. The etching temperature is controlled at 55°C. After etching, it is washed with deionized water and alcohol to remove the etching solution to obtain a transparent conductive film with a double-layer grid structure.

[0068] Example 5

[0069] A method for preparing a transparent conductive film having a double-layer grid structure mainly comprises the following steps:

[0070] Step 1: Clean the transparent flexible substrate (flexible glass) with alcohol and acetone. After the transparent flexible substrate is dried, a copper film is prepared on the surface of the transparent flexible substrate using vacuum thermal evaporation technology. When performing thermal evaporation coating, the background vacuum of the magnetron sputtering system is reduced to 1.0×10 -3 Pa, regulating the heating current to 100A, evaporating the metallic copper particles, and depositing a 100nm thick copper film;

[0071] Step 2: A self-cracking film with a thickness of 9 μm was prepared on the surface of the copper film by spin coating using a pure acrylic emulsion as a self-cracking agent. The film was dried at 30°C to allow the self-cracking film to naturally crack to form a mesh-like cracking template. The average mesh diameter of the cracks in the mesh-like cracking template was 80 μm, and the crack grid line width was 4-8 μm.

[0072] Step 3: Place the semi-finished product obtained in step 2 on the sample stage of the magnetron sputtering system and pump the background vacuum of the magnetron sputtering system to 1.0×10 -3 Pa, high-purity (99.999%) argon gas was introduced, the pressure was adjusted to 1.0 Pa, the distance between the target and the substrate was fixed at 10 cm, the sputtering power was 100 W, and the ceramic BaSnO3 target was sputtered to obtain a 50 nm thick BaSnO3 film at room temperature;

[0073] Step 4: Use acetone and ultrasonic cleaning to remove the self-cracking film on the copper film. After cleaning, a BaSnO3 grid can be obtained;

[0074] Step 5: Evenly spray the etching solution onto the surface of the BaSnO3 grid and seal it for 10 minutes. The etching solution used is a 10% FeCl3 solution. The etching temperature is controlled at 40°C. After etching, it is washed with deionized water and alcohol to remove the etching solution to obtain a transparent conductive film with a double-layer grid structure.

[0075] Example 6

[0076] A method for preparing a transparent conductive film having a double-layer grid structure mainly comprises the following steps:

[0077] Step 1: Clean the transparent flexible substrate (flexible glass) with alcohol and acetone. After the transparent flexible substrate is dried, a copper film is prepared on the surface of the flexible glass substrate using pulsed laser deposition technology. When performing pulsed laser deposition, the background vacuum is reduced to 1.0×10 -3 Pa, the distance between the target and the substrate was fixed at 5 cm, the laser energy was 300 mJ, the frequency was 5 times / s, and a 100 nm thick copper film was deposited;

[0078] Step 2: A self-cracking film with a thickness of 9 μm is prepared on the surface of the copper film by spin coating using a silicone acrylic emulsion as a self-cracking agent. The film is dried at 30°C to allow the self-cracking film to naturally crack to form a mesh-like cracking template. The average mesh diameter of the cracks in the mesh-like cracking template is 80 μm, and the crack grid line width is 4-8 μm.

[0079] Step 3: Place the semi-finished product obtained in step 2 on the sample stage of the magnetron sputtering system and pump the background vacuum of the magnetron sputtering system to 1.0×10 -3 Pa, high-purity (99.999%) argon gas was introduced, the pressure was adjusted to 1.0 Pa, the distance between the target and the substrate was fixed at 10 cm, the sputtering power was 100 W, and the ceramic BaSnO3 target was sputtered to obtain a 100 nm thick BaSnO3 film at room temperature;

[0080] Step 4: Use acetone and ultrasonic cleaning to remove the self-cracking film on the copper film. After cleaning, a BaSnO3 grid can be obtained;

[0081] Step 5: Evenly spray the etching solution onto the surface of the BaSnO3 grid and seal it for 10 minutes. The etching solution used is a 10% FeCl3 solution. The etching temperature is controlled at 40°C. After etching, it is washed with deionized water and alcohol to remove the etching solution to obtain a transparent conductive film with a double-layer grid structure.

[0082] Comparative Example 1

[0083] A method for preparing a conductive film mainly comprises the following steps:

[0084] Step 1: Clean the transparent flexible substrate (transparent flexible plastic) with alcohol and dry it;

[0085] Step 2: Using an acrylic emulsion as a self-cracking agent, a 10 μm thick self-cracking film is prepared on the surface of the copper film by a pull-up coating method. The film is dried at 60°C to allow the self-cracking film to naturally crack to form a mesh-like cracking template. The average mesh diameter of the cracks in the mesh-like cracking template is 60 μm, and the crack grid line width is 4-7 μm.

[0086] Step 3: After the transparent flexible substrate is dried, a copper film is prepared on the surface of the transparent flexible substrate by using a magnetron sputtering coating method. During the magnetron sputtering coating, the background vacuum of the magnetron sputtering system is pumped to 1.0×10 -3 Pa, high-purity (99.999%) argon gas was introduced, the pressure was adjusted to 1.0 Pa, the distance between the target and the substrate was fixed at 10 cm, the sputtering power was 100 W, and the metal copper target was sputtered to obtain a 100 nm thick copper film;

[0087] Step 4: Use acetone and ultrasonic cleaning to remove the self-cracking film on the copper film. After cleaning, a copper grid can be obtained.

[0088] First, the transmittance and sheet resistance of the products obtained in Examples 1-6 were tested. The average transmittance of the products in the visible light band was measured using a UV-visible spectrophotometer. The sheet resistance of the products was measured using a four-probe resistance test system. The results are shown in Table 1.

[0089] Table 1 Transmittance and sheet resistance of the products obtained in Examples 1-6

[0090]

[0091] As shown in Table 1, the transparent conductive film prepared using the method of the present invention has a transmittance greater than 80% and a sheet resistance as low as 4 Ω / sq, demonstrating its high transmittance and low sheet resistance. This can effectively improve device stability and display quality, and reduce internal resistance heat dissipation, for optoelectronic devices, particularly large-area displays.

[0092] Next, the resistance change rates of the products obtained in Examples 1-6 and Comparative Example 1 were analyzed. The resistance change rates of the products were tested in an accelerated aging environment at 85°C and 85% relative humidity for different durations (24 hours and 240 hours). The results are shown in Table 2.

[0093] Table 2 Resistance change rate of the products obtained in Examples 1-6 and Comparative Example 1

[0094]

[0095] As shown in Table 2, a conventional film (such as that prepared in Comparative Example 1) loses its conductivity after 24 hours. However, the transparent conductive film prepared in the present invention exhibits a resistance change rate of no more than 5% after 240 hours, demonstrating the excellent stability of the transparent conductive film of the present invention.

[0096] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any equivalent changes or modifications made based on the essence of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a transparent conductive film having a double-layer grid structure, characterized in that: The invention comprises a transparent flexible substrate and a double-layer grid structure provided on the transparent flexible substrate, wherein the double-layer grid structure is composed of a copper grid and a BaSnO3 grid. The BaSnO3 grid covers the top surface of the copper grid. The thickness of the copper grid is 100-200 nm, and the thickness of the BaSnO3 grid is 50-200 nm. The method for preparing the transparent conductive film comprises the following steps: Step 1: Clean the transparent flexible substrate, and after the transparent flexible substrate is dried, form a copper film on the surface of the transparent flexible substrate using a vacuum coating technology; Step 2: using a self-cracking agent to prepare a self-cracking film on the surface of the copper film, drying it at room temperature to 80°C, so that the self-cracking film naturally cracks to form a network cracking template; Step 3: Using magnetron sputtering technology to prepare a layer of BaSnO3 thin film on the mesh cracking template and the outer surface of the copper film; Step 4: Use acetone and ultrasonic cleaning to remove the self-cracking film on the copper film to obtain a BaSnO3 grid; Step 5: Spray an etching solution onto the surface of the BaSnO3 grid and seal it to allow it to stand to etch the copper film into a copper grid, thereby obtaining a transparent conductive film with a double-layer grid structure. Among them, in step five, the etching solution is evenly sprayed on the surface of the BaSnO3 grid and sealed and left to stand for 2 to 10 minutes. The etching solution used is a FeCl3 solution with a concentration of 10 to 40%. The etching temperature is controlled at 40 to 60°C. After the etching is completed, it is cleaned with deionized water and alcohol to remove the etching solution.

2. The method for preparing a transparent conductive film having a double-layer grid structure according to claim 1, wherein: In step 1, the transparent flexible substrate is a flexible glass or a flexible transparent plastic with a thickness of 30-120 μm.

3. The method for preparing a transparent conductive film having a double-layer grid structure according to claim 1, wherein: In step 1, the vacuum coating technology is magnetron sputtering coating, thermal evaporation coating or pulsed laser deposition.

4. The method for preparing a transparent conductive film having a double-layer grid structure according to claim 1, wherein: In step 2, the self-cracking agent is any one of pure acrylic emulsion, silicone acrylic emulsion, acrylic acid emulsion or nail polish.

5. The method for preparing a transparent conductive film having a double-layer grid structure according to claim 1, wherein: In step 2, the thickness of the self-cracking film is 5-15 μm.

6. The method for preparing a transparent conductive film having a double-layer grid structure according to claim 1, wherein: In step 2, a self-cracking film is prepared by a Czochralski coating method or a spin coating method.

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