Method for fabricating random grid transparent conductive thin films using micro / nano sphere self-assembly mask

Abstract

This invention belongs to the field of optical electronic device fabrication technology, and relates to a method for preparing transparent conductive films. Specifically, it provides a method for preparing random mesh transparent conductive films using a self-assembled mask of micro / nanospheres, thereby solving many problems existing in current metal mesh film preparation methods. This invention uses a micro / nanosphere self-assembly method to form a mask layer, then prepares a transparent conductive film layer on the mask layer, and finally removes the mask layer to obtain a random mesh transparent conductive film. Compared with traditional regular metal mesh films, the transparent conductive mesh film prepared by this invention has randomly distributed pores, which helps to avoid problems such as reduced light transmission and imaging effect caused by higher-order diffraction of the mesh. Furthermore, the random mesh transparent conductive film prepared by this invention has higher light transmission performance while ensuring high conductivity, and the fabrication process is simpler, more efficient, and compatible with complex large-area curved surfaces, thus having broader application prospects.

Description

Technical Field

[0001] This invention belongs to the field of optical and electronic device fabrication technology, and relates to a method for preparing transparent conductive films. Specifically, it provides a method for preparing a random grid transparent conductive film using a micro / nano sphere self-assembly mask. Background Technology

[0002] With the rapid development of modern optoelectronic technology, high-performance transparent conductive films have become key functional materials in many cutting-edge technology fields. Transparent conductive films have unique optoelectronic properties and play an irreplaceable role in applications such as solar cells, flexible displays, intelligent sensing, infrared imaging, precision guidance, and electromagnetic countermeasures. Especially in the field of infrared technology, transparent conductive films not only need to meet the basic requirements of light transmission and conductivity, but also need to have multiple functional characteristics such as multi-band compatibility, electromagnetic shielding, and environmental tolerance. However, infrared transparent conductive films have the problem of the contradiction between plasma wavelength and conductivity, which makes it difficult for traditional material systems to achieve a performance balance between wide-spectrum high transmittance and low resistivity, greatly limiting the development and application of infrared transparent conductive films.

[0003] Currently, infrared transparent conductive films mainly include metal compound films, graphene films, carbon nanotube films, ultrathin metal films, metal nanowires, and metal mesh films. Among them, metal compound films are affected by plasma wavelengths, resulting in a sharp decrease in transmittance in the far-infrared band. Low-dimensional carbon graphene films and carbon nanotube films can achieve high far-infrared transmittance, but they are prone to discontinuity and agglomeration problems during preparation. Ultrathin metal films have excessively high requirements for growth technology. Metal nanowires are nanowires made of metal and can replace continuous metal films. Light can pass through the gaps between nanowires, thereby improving the light transmittance of the film, but the improvement effect is limited. In addition, nanowires are prone to agglomeration, resulting in unstable conductivity. Metal mesh films are formed by patterned and connected metal mesh lines. By changing the periodic spacing, linewidth, and other dimensional parameters of the mesh units, both transmittance and conductivity can be adjusted simultaneously. The introduced mesh structure and porous structure can improve long-wavelength transmittance while maintaining low sheet resistance, showing broad application prospects.

[0004] Traditional methods for fabricating metal mesh films mainly employ processes such as photolithography, mask-assisted printing, screen printing, gravure printing, and inkjet printing. Among these, photolithography suffers from problems such as expensive equipment and complex processes; mask-assisted printing struggles to achieve complex patterning; gravure printing is hampered by expensive equipment and ink transfer issues; screen printing is prone to screen clogging; and inkjet printing suffers from nozzle clogging. These technological bottlenecks severely restrict the large-scale application of high-performance metal mesh films. To address this issue, this invention proposes a method for fabricating random mesh transparent conductive films using a self-assembled mask of micro / nanospheres. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a random mesh transparent conductive film using a self-assembled mask of micro / nanospheres, thereby solving many problems existing in the preparation of metal mesh films. This invention employs a self-assembly method of micro / nanospheres to form a mask layer, then prepares a transparent conductive film layer on the mask layer, and finally removes the mask layer to obtain a random mesh transparent conductive film. Compared with traditional regular metal mesh films, the transparent conductive mesh film prepared by this invention has randomly distributed pores, which helps to avoid problems such as reduced light transmission and imaging effect caused by higher-order diffraction of the mesh. Furthermore, the random mesh transparent conductive film prepared by this invention maintains high conductivity while exhibiting higher light transmission performance, and the preparation process is simpler, more efficient, and compatible with complex large-area curved surfaces, thus having broader application prospects.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for fabricating a random grid transparent conductive thin film using a self-assembled mask of micro / nano spheres includes the following steps:

[0008] Step 1. Disperse the micro-nano spheres in a dispersant and then ultrasonically disperse them to obtain a micro-nano sphere dispersion;

[0009] Step 2. Deposit the micro-nano sphere dispersion onto the substrate using an atomization spraying process, and wait for the dispersant to completely evaporate to obtain a self-assembled micro-nano sphere template layer;

[0010] Step 3. Using the self-assembled micro / nano sphere layer as a mask, a transparent conductive thin film layer is prepared on the surface of the mask.

[0011] Step 4. Remove the mask to obtain a random grid transparent conductive film.

[0012] Furthermore, in step 1, the micro-nano spheres are either polymer micro-nano spheres or inorganic micro-nano spheres. The polymer micro-nano spheres are made of polystyrene (PS), polymethyl methacrylate (PMMA), or polyacrylate, while the inorganic micro-nano spheres are made of silicon dioxide (SiO2), titanium dioxide (TiO2), iron tetroxide (Fe3O4), polyvinyl alcohol (PVA), alumina, or glass.

[0013] Furthermore, in step 1, the diameter of the micro / nanospheres is 100 nm to 50 µm.

[0014] Furthermore, in step 1, the dispersant is one or more of the following: water, ethanol, isopropanol, ethylene glycol, n-butanol, polyethylene glycol, methanol, acetone, ethyl acetate, and ethyl lactate.

[0015] Furthermore, in step 1, the concentration of the micro / nanosphere dispersion is 1 mg / ml to 50 mg / ml.

[0016] Furthermore, in step 2, the substrate is a flexible substrate or a rigid substrate, and the substrate material is transparent glass, MgO, MgF2, ZnS, ZnSe, PET, PE, PMMA, PDMS, PC, PI, PFA, PTFE, COP, PVC, ETFE, quartz sheet or alumina.

[0017] Furthermore, in step 2, the amount of micro / nanosphere dispersion used is 0.02 ml / cm². 2 ~2 ml / cm 2 .

[0018] Furthermore, in step 2, the spraying parameters are as follows: the nozzle diameter of the spray gun is 0.8 mm, the spraying distance is 10 cm, the spray gun width is 5 cm, the air pressure is 20 Psi ~ 45 Psi, the spraying speed is 5 ml / min ~ 15 ml / min, the ambient humidity is 45% ~ 65%, and the ambient temperature is 22℃ ~ 28℃.

[0019] Furthermore, in step 3, the transparent conductive thin film layer is made of oxide films such as ITO, IZO, FTO, AZO, GZO, and CTO; metal films such as Au, Ag, Cu, Ni, Cr, and Ti; nanowire thin films such as Cu nanowires, Au nanowires, Al nanowires, and Ag nanowires; conductive polymer thin films; or composite films composed of a combination of the above-mentioned thin films.

[0020] Furthermore, in step 4, the mask removal methods include gas gun removal, ultrasonic etching, chemical reaction removal, and physical wiping removal.

[0021] Based on the above technical solution, the beneficial effects of the present invention are as follows:

[0022] This invention provides a method for preparing a random grid transparent conductive film using a micro / nanosphere self-assembly mask. Based on the synergistic design of the micro / nanosphere dispersion and atomization spraying process, the atomizing nozzle achieves a uniform atomization effect on the micro / nanosphere dispersion. After the dispersion is atomized and sprayed onto the substrate surface, during solvent drying, the micro / nanospheres are ensured to form densely packed, independent, and non-crosslinked micro / nanosphere agglomerates on the substrate through adsorption and aggregation self-assembly. These densely packed micro / nanosphere agglomerates are used as a mask for further deposition of the conductive film. Finally, the micro / nanosphere mask is removed to obtain the random grid transparent conductive film. This method features simple process, low equipment cost, and short cycle time. Furthermore, the random grid transparent conductive film prepared by this invention effectively improves the transmittance of the transparent conductive film in the infrared region while ensuring high conductivity, achieving broadband, high transmittance, and high conductivity characteristics, and can be applied to large-area substrate surfaces with complex curved surfaces. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart of the method for preparing a random grid transparent conductive film using a self-assembled mask of micro / nano spheres in this invention.

[0024] Figure 2 This is an optical microscope image of the microsphere template layer and the random grid silver nanowire thin film in Example 1 of the present invention.

[0025] Figure 3 The images show the transmittance curves of the random mesh silver nanowire film in Example 1 and the silver nanowire film in Comparative Example 1.

[0026] Figure 4 This is an optical microscope image of the microsphere template layer and the random grid silver nanowire thin film in Embodiment 2 of the present invention.

[0027] Figure 5 This is a transmittance curve of the random mesh silver nanowire thin film in Embodiment 2 of the present invention.

[0028] Figure 6 This is an optical microscope image of the microsphere template layer and the random grid silver nanowire thin film in Example 3 of the present invention.

[0029] Figure 7 The images show the transmittance curves of the random mesh silver nanowire film in Example 3 of the present invention and the silver nanowire film in Comparative Example 2.

[0030] Figure 8 This is an optical microscope image of the microsphere template layer and the random grid ITO transparent conductive film in Embodiment 4 of the present invention.

[0031] Figure 9 The images show the light transmittance curves of the random mesh ITO transparent conductive film in Example 4 of the present invention and the ITO transparent conductive film in Comparative Example 3.

[0032] Figure 10 This is an optical microscope image of the microsphere template layer and the random grid Cr / Au transparent conductive film in Embodiment 5 of the present invention.

[0033] Figure 11 The image shows the light transmittance curves of the random grid Cr / Au transparent conductive film in Example 5 of the present invention and the Cr / Au transparent conductive film in Comparative Example 4.

[0034] Figure 12 This is an optical microscope image of the microsphere template layer and the random grid Cr / Au transparent conductive film in Embodiment 6 of the present invention.

[0035] Figure 13 The image shows the light transmittance curves of the random grid Cr / Au transparent conductive film in Example 6 of the present invention and the Cr / Au transparent conductive film in Comparative Example 4.

[0036] Figure 14 This is an optical microscope image of the microsphere template layer and the random grid Cr / Au transparent conductive film in Embodiment 7 of the present invention.

[0037] Figure 15 The image shows the light transmittance curves of the random grid Cr / Au transparent conductive film in Example 7 of the present invention and the Cr / Au transparent conductive film in Comparative Example 5. Detailed Implementation

[0038] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0039] Example 1: This example provides a method for fabricating a random grid transparent conductive thin film using a self-assembled mask of micro / nano spheres. The process is as follows: Figure 1 As shown, the substrate is Corning glass with dimensions of 25 mm (length), 25 mm (width), and 0.7 mm (height). The transparent conductive film is made of silver nanowires with a diameter of 25 nm to 30 nm and a length of 10 µm to 30 µm. Isopropanol is used as the dispersant for the silver nanowires, and the concentration after dispersion is 5 mg / ml. The specific steps include:

[0040] Step 1. Using anhydrous ethanol as a dispersant, SiO2 microspheres with a diameter of 10 micrometers were dispersed in the dispersant and ultrasonically dispersed for 2 min to ensure that the micro-nano spheres were fully dispersed in the dispersant, resulting in a SiO2 microsphere dispersion with a concentration of 10 mg / ml.

[0041] Step 2. The SiO2 microsphere dispersion is sprayed onto the substrate using an atomization spraying process. The dispersant is allowed to completely evaporate, forming a microsphere template layer. During the spraying process, the spraying amount of the SiO2 microsphere dispersion is 0.1 ml / cm². 2 0.16 ml / cm 2 0.24 ml / cm 2 0.32 ml / cm 2 Spraying parameters: spray gun nozzle diameter is 0.8 mm, spraying distance is 10 cm, spray gun width is 5 cm, air pressure is 20 Psi ~ 45 Psi, spraying speed is 5 ml / min ~ 15 ml / min, ambient humidity is 45% ~ 65%, ambient temperature is 22℃ ~ 28℃.

[0042] Step 3. Spin-coat 200 µL of silver nanowire dispersion onto the microsphere template layer to form a transparent conductive layer; the spin-coating time is 60 s, the spin-coating speed is 1000 rpm, and the spin-coating acceleration is 2000 rpm / s.

[0043] Step 4. Blow the sample surface with a nitrogen gun for 30 seconds to remove the SiO2 microspheres, and obtain a random grid silver nanowire film, which is a random grid transparent conductive film.

[0044] The beneficial effects of this embodiment will be described in detail below with reference to the test results. The transmittance was measured using a UV-Vis-NIR spectrophotometer and a Fourier transform infrared microscopy spectrometer, and the sheet resistance was measured using the four-probe resistance method. For comparative illustration, Comparative Example 1 is provided here, specifically: 200 µL of silver nanowire dispersion was spin-coated onto a substrate to form a silver nanowire thin film; the spin-coating process was the same as in step 3.

[0045] like Figure 2 The image shown is an optical microscope image of the microsphere template layer and the random grid silver nanowire thin film prepared in this embodiment. The coating amount of the SiO2 microsphere dispersion was 0.1 ml / cm. 2 At that time, the microsphere template is shown in the upper left figure, and the random mesh silver nanowire film is shown in the lower left figure; when the spraying amount of SiO2 microsphere dispersion is 0.32 ml / cm 2The microsphere template is shown in the upper right figure, and the random grid silver nanowire film is shown in the lower right figure. As can be seen from the figures, with the assistance of the spraying process, the silica microspheres can self-assemble on the Corning glass substrate to form a dispersed aggregate structure. By controlling the amount of dispersion liquid used, the size and surface distribution density of the silica aggregates can be effectively adjusted to prepare microsphere templates with different silica duty cycles. After depositing the silver nanowire transparent conductive film and removing the silica microsphere template, the silver nanowire transparent conductive film replicates the spatial distribution characteristics of the microsphere template to form the corresponding void structure. Finally, a silver nanowire transparent conductive film with a random grid structure is prepared on Corning glass.

[0046] The random mesh silver nanowire thin film prepared in this embodiment achieved a transmittance of over 85% at 550 nm. This was achieved when the SiO2 microsphere dispersion was sprayed at a concentration of 0.1 ml / cm³. 2 0.16 ml / cm 2 0.24 ml / cm 2 0.32 ml / cm 2 When the sheet resistance of the randomly meshed silver nanowire films prepared were 14 ohm / sq, 40 ohm / sq, 34 ohm / sq, and 35 ohm / sq, respectively, the transmittance at 5 µm was 34.7%, 56.3%, 56.2%, and 60%, respectively. In contrast, the silver nanowire film prepared in Comparative Example 1 had a sheet resistance of 14 ohm / sq and a transmittance of 25.6% at 5 µm. Especially when the SiO2 microsphere dispersion spraying amount was 0.32 ml / cm... 2 Compared to the silver nanowire film prepared in Comparative Example 1, the average transmittance of the random mesh silver nanowire film prepared in this embodiment is increased by 27.7% in the range of 2 µm to 5 µm; the coating amount of SiO2 microsphere dispersion is 0.1 ml / cm. 2 0.32 ml / cm 2 For example, the transmittance curves of the random mesh silver nanowire film prepared in this embodiment and the silver nanowire film prepared in Comparative Example 1 are as follows: Figure 3 As shown.

[0047] Example 2 provides a method for preparing a random grid transparent conductive film using a self-assembled mask of micro / nanospheres. The substrate is Corning glass with dimensions of 25 mm (length), 25 mm (width), and 0.7 mm (height). The transparent conductive film is made of silver nanowires with a diameter of 25 nm to 30 nm and a length of 10 µm to 30 µm. Isopropanol is used as the dispersant for the silver nanowires, and the concentration after dispersion is 5 mg / ml. The specific steps include:

[0048] Step 1. Using anhydrous ethanol as a dispersant, SiO2 microspheres with a diameter of 10 micrometers were dispersed in the dispersant and ultrasonically dispersed for 2 min to ensure that the micro-nano spheres were fully dispersed in the dispersant, resulting in a SiO2 microsphere dispersion with a concentration of 10 mg / ml.

[0049] Step 2. The SiO2 microsphere dispersion is sprayed onto the substrate using an atomization spraying process. The dispersant is allowed to completely evaporate, forming a microsphere template layer. During the spraying process, the spraying amount of the SiO2 microsphere dispersion is 0.32 ml / cm². 2 Spraying parameters: spray gun nozzle diameter is 0.8 mm, spraying distance is 10 cm, spray gun width is 5 cm, air pressure is 20 Psi ~ 45 Psi, spraying speed is 5 ml / min ~ 15 ml / min, ambient humidity is 45% ~ 65%, ambient temperature is 22℃ ~ 28℃.

[0050] Step 3. Spin-coat 200 µL of silver nanowire dispersion onto the microsphere template layer to form a transparent conductive layer; the spin-coating time is 60 s, the spin-coating speeds are 500 rpm, 750 rpm, 1000 rpm, 1250 rpm, and 1500 rpm, and the spin-coating acceleration is 2000 rpm / s;

[0051] Step 4. Blow the sample surface with a nitrogen gun for 30 seconds to remove the SiO2 microspheres, and obtain a random grid silver nanowire film, which is a random grid transparent conductive film.

[0052] The beneficial effects of this embodiment will be explained in detail below with reference to testing, such as... Figure 4 The images shown are optical microscope images of the microsphere template layer and the random grid silver nanowire film prepared in this embodiment. When the spin-coating speed of the silver nanowire dispersion is 500 rpm, the microsphere template is shown in the upper left image, and the random grid silver nanowire film is shown in the lower left image; when the spin-coating speed of the silver nanowire dispersion is 1250 rpm, the microsphere template is shown in the upper middle image, and the random grid silver nanowire film is shown in the lower middle image; when the spin-coating speed of the silver nanowire dispersion is 1500 rpm... At rpm, the microsphere template is shown in the upper right figure, and the random grid silver nanowire film is shown in the lower right figure. As can be seen from the figures, with the assistance of the spraying process, the silica microspheres self-assemble on the Corning glass substrate surface to form a dispersed aggregate structure, and the microsphere templates prepared with the same spraying parameters have similar morphologies. After depositing the silver nanowire transparent conductive film and removing the silica microsphere template, the silver nanowire transparent conductive film replicates the spatial distribution characteristics of the silica template, forming the corresponding void structure. Finally, a silver nanowire transparent conductive film with a random grid structure is prepared on Corning glass.

[0053] When the spin-coating speeds of the silver nanowire dispersion were 500 rpm, 750 rpm, 1000 rpm, 1250 rpm, and 1500 rpm, the transmittance of the random mesh silver nanowire film prepared in this embodiment at 550 nm was 91%, 90.2%, 91.0%, 92.4%, and 95.2%, respectively; the sheet resistance was 33.6 ohm / sq, 80 ohm / sq, 40 ohm / sq, 72 ohm / sq, and 71 ohm / sq, respectively; and the transmittance at 5 µm was 57.6%, 62.3%, 59.1%, 68%, and 64.1%, respectively. Taking the spin-coating speeds of the silver nanowire dispersion at 500 rpm, 1250 rpm, and 1500 rpm as examples, the transmittance curves of the random mesh silver nanowire film prepared in this embodiment are as follows: Figure 5 As shown.

[0054] Example 3 provides a method for preparing a random grid transparent conductive film using a self-assembled mask of micro / nano spheres. The substrate is a PE substrate with a length and width of 25 mm. The PE substrate is ultrasonically cleaned sequentially with deionized water and anhydrous ethanol, followed by oxygen plasma treatment for 5 min. The transparent conductive film is made of silver nanowires. The specific steps include:

[0055] Step 1. Using anhydrous ethanol as a dispersant, SiO2 microspheres with a diameter of 10 micrometers were dispersed in the dispersant and ultrasonically dispersed for 2 min to ensure that the micro-nano spheres were fully dispersed in the dispersant, resulting in a SiO2 microsphere dispersion with a concentration of 10 mg / ml.

[0056] Step 2. The SiO2 microsphere dispersion is sprayed onto the substrate using an atomization spraying process. The dispersant is allowed to completely evaporate, forming a microsphere template layer. During the spraying process, the spraying amount of the SiO2 microsphere dispersion is 0.32 ml / cm². 2 Spraying parameters: spray gun nozzle diameter is 0.8 mm, spraying distance is 10 cm, spray gun width is 5 cm, air pressure is 20 Psi ~ 45 Psi, spraying speed is 5 ml / min ~ 15 ml / min, ambient humidity is 45% ~ 65%, ambient temperature is 22℃ ~ 28℃.

[0057] Step 3. Spin-coat 200 µL of silver nanowire dispersion onto the microsphere template layer to form a transparent conductive layer; the spin-coating time is 60 s, the spin-coating speed is 1000 rpm, and the spin-coating acceleration is 2000 rpm / s.

[0058] Step 4. Blow the sample surface with a nitrogen gun for 30 seconds to remove the SiO2 microspheres, and obtain a random grid silver nanowire film, which is a random grid transparent conductive film.

[0059] The beneficial effects of this embodiment will be described in detail below with reference to the test. For comparison, Comparative Example 2 is provided here. Specifically, 200 µL of silver nanowire dispersion was spin-coated onto the substrate to form a silver nanowire film. The spin-coating process is the same as in step 3.

[0060] like Figure 6 The image shows an optical microscope image of the microsphere template layer and the random grid silver nanowire thin film prepared in this embodiment. As can be seen from the image, with the assistance of the spraying process, the silica microspheres self-assemble and are uniformly dispersed on the PE substrate to form a microsphere template. After depositing the silver nanowire transparent conductive film and removing the silica microsphere template, the silver nanowire transparent conductive film replicates the spatial distribution characteristics of the silica microsphere template and forms the corresponding void structure. Finally, a silver nanowire transparent conductive film with a random grid structure is prepared on the PE substrate.

[0061] The silver nanowire film prepared in Comparative Example 2 had a transmittance of 76.5% at 550 nm and a sheet resistance of 15 ohm / sq, and a transmittance of 20.3% at 5 µm. The random mesh silver nanowire film prepared in this example had a transmittance of 80.9% at 550 nm and a sheet resistance of 36 ohm / sq, and a transmittance of 39.5% at 5 µm. Compared to the silver nanowire film prepared in Comparative Example 2, the average transmittance of the random mesh silver nanowire film prepared in this example in the 2 µm–25 µm range was increased by 14%. The transmittance curves of the random mesh silver nanowire film prepared in this example and the silver nanowire film prepared in Comparative Example 2 are shown below. Figure 7 As shown.

[0062] Example 4 provides a method for fabricating a random grid transparent conductive film using a micro / nano sphere self-assembly mask. The substrate is Corning glass with dimensions of 25 mm (length), 25 mm (width), and 0.7 mm (height), and the transparent conductive film is an ITO film. The method includes the following steps:

[0063] Step 1. Using anhydrous ethanol as a dispersant, SiO2 microspheres with a diameter of 10 micrometers were dispersed in the dispersant and ultrasonically dispersed for 2 min to ensure that the micro-nano spheres were fully dispersed in the dispersant, resulting in a SiO2 microsphere dispersion with a concentration of 10 mg / ml.

[0064] Step 2. The SiO2 microsphere dispersion is sprayed onto the substrate using an atomization spraying process. The dispersant is allowed to completely evaporate, forming a microsphere template layer. During the spraying process, the spraying amount of the SiO2 microsphere dispersion is 0.24 ml / cm². 2Spraying parameters: spray gun nozzle diameter is 0.8 mm, spraying distance is 10 cm, spray gun width is 5 cm, air pressure is 20 Psi ~ 45 Psi, spraying speed is 5 ml / min ~ 15 ml / min, ambient humidity is 45% ~ 65%, ambient temperature is 22℃ ~ 28℃.

[0065] Step 3. An ITO film with a thickness of 150 nm is deposited on the microsphere template layer using magnetron sputtering, and the ITO film is annealed to form a transparent conductive layer. During the magnetron sputtering process, the sputtering power is 15 W and the working pressure is 0.2 Pa. During the annealing process, the annealing temperature is 350℃ and the holding time is 1 hour.

[0066] Step 4. Use a nitrogen gun to blow on the sample surface to remove the SiO2 microspheres, and obtain a random grid ITO transparent conductive film.

[0067] The beneficial effects of this embodiment will be described in detail below with reference to the test. For comparison purposes, Comparative Example 3 is provided here, which is as follows: A 150 nm thick ITO film is deposited on the substrate using magnetron sputtering, and the ITO film is annealed to form an ITO transparent conductive film. The magnetron sputtering and annealing are the same as in step 3.

[0068] like Figure 8 The image shows an optical microscope image of the microsphere template layer and the random grid ITO transparent conductive film prepared in this embodiment. As can be seen from the image, with the assistance of the spraying process, the silica microspheres self-assemble on the surface of the Corning glass substrate to form a dispersed aggregate structure. Using the silica microsphere template as a microsphere template, after depositing the ITO transparent conductive film and removing the silica microsphere template, the ITO transparent conductive film replicates the spatial distribution characteristics of the microsphere template to form the corresponding void structure. Finally, an ITO transparent conductive film with a random grid structure is prepared on Corning glass.

[0069] The transmittance at 550 nm of the ITO transparent conductive film prepared in Comparative Example 3 and the random mesh ITO transparent conductive film prepared in this embodiment are 96% and 96.1%, respectively, and their sheet resistances are 32 ohm / sq and 87.7 ohm / sq, respectively. Their transmittance at 5 µm is 11.4% and 43.2%, respectively. Compared to the ITO transparent conductive film prepared in Comparative Example 3, the average transmittance of the random mesh ITO transparent conductive film prepared in this embodiment is increased by 28.2% in the 2 µm to 5 µm range. The transmittance curves of the random mesh ITO transparent conductive film prepared in this embodiment and the ITO transparent conductive film prepared in Comparative Example 3 are shown below. Figure 9 As shown.

[0070] Example 5 provides a method for preparing a random grid transparent conductive film using a micro / nano sphere self-assembly mask. The substrate is Corning glass with dimensions of 25 mm (length), 25 mm (width), and 0.7 mm (height). The transparent conductive film is an Au film. To improve the adhesion of the Au film, a transition layer Cr is provided between the Au film and the microsphere template layer. The method specifically includes the following steps:

[0071] Step 1. Using a mixed solvent of anhydrous ethanol and water as a dispersant, SiO2 microspheres with a diameter of 10 micrometers were dispersed in the dispersant and ultrasonically dispersed for 2 min to ensure that the microspheres were fully dispersed in the dispersant, thus obtaining a SiO2 microsphere dispersion. The volume ratio of anhydrous ethanol to water was 10:1, and the concentrations of the SiO2 microsphere dispersions were 1.25 mg / ml, 2.5 mg / ml, 5 mg / ml, 10 mg / ml, 15 mg / ml, and 20 mg / ml, respectively.

[0072] Step 2. The SiO2 microsphere dispersion is sprayed onto the substrate using an atomization spraying process. The dispersant is allowed to completely evaporate, forming a microsphere template layer. During the spraying process, the spraying amount of the SiO2 microsphere dispersion is 0.24 ml / cm². 2 Spraying parameters: spray gun nozzle diameter is 0.8 mm, spraying distance is 10 cm, spray gun width is 5 cm, air pressure is 20 Psi ~ 45 Psi, spraying speed is 5 ml / min ~ 15 ml / min, ambient humidity is 45% ~ 65%, ambient temperature is 22℃ ~ 28℃.

[0073] Step 3. A 2 nm thick Cr transition layer and a 20 nm thick Au transparent conductive layer are sequentially deposited on the microsphere template layer using magnetron sputtering. During the magnetron sputtering process, the sputtering power is 20 W and the working pressure is 0.6 Pa.

[0074] Step 4. Use a nitrogen gun to blow the sample surface to remove the SiO2 microspheres, and obtain a random grid Cr / Au transparent conductive film.

[0075] The beneficial effects of this embodiment will be described in detail below with reference to the test. For comparison purposes, Comparative Example 4 is provided here, which is as follows: A Cr transition layer with a thickness of 2 nm and an Au transparent conductive layer with a thickness of 20 nm are sequentially deposited on the substrate using a magnetron sputtering process to form a Cr / Au transparent conductive film. The magnetron sputtering process is the same as step 3.

[0076] like Figure 10The images shown are optical microscope images of the microsphere template layer and the random gridded Cr / Au transparent conductive film prepared in this embodiment. When the concentration of the SiO2 microsphere dispersion is 2.5 mg / ml, the microsphere template is shown in the upper left image, and the random gridded silver nanowire film is shown in the lower left image; when the concentration of the SiO2 microsphere dispersion is 10 mg / ml, the microsphere template is shown in the upper middle image, and the random gridded silver nanowire film is shown in the lower middle image; when the concentration of the SiO2 microsphere dispersion is 2 .... At a concentration of mg / ml, the microsphere template is shown in the upper right figure, and the random grid silver nanowire film is shown in the lower right figure. As can be seen from the figures, with the assistance of the spraying process, the silica microspheres self-assemble on the Corning glass substrate surface to form a dispersed aggregate structure. The size and surface distribution density of the silica aggregates can also be adjusted by the concentration of the silica dispersion, thus preparing microsphere templates with different silica duty cycles. After depositing the Cr / Au transparent conductive film and removing the silica microsphere template, the Cr / Au transparent conductive film replicates the spatial distribution characteristics of the microsphere template, forming the corresponding void structure. Finally, a Cr / Au transparent conductive film with a random grid structure is prepared on Corning glass.

[0077] The Cr / Au transparent conductive film prepared in Comparative Example 4 had a transmittance of 42.9% at 550 nm, a sheet resistance of 2.7 ohm / sq, and a transmittance of 0.3% at 5 µm. When the concentration of SiO2 microsphere dispersion was 1.25 mg / ml, 2.5 mg / ml, 5 mg / ml, 10 mg / ml, 15 mg / ml, and 20 mg / ml, the random grid Cr / Au transparent conductive film prepared in this example had transmittances of 46.1%, 52.9%, 58.5%, 66.9%, 69.7%, and 75.2% at 550 nm, and sheet resistances of 3.6 ohm / sq, 4.6 ohm / sq, 6 ohm / sq, 8.2 ohm / sq, 9.4 ohm / sq, and 12.4 ohm / sq, respectively, at 5 µm. The transmittance at µm was 6.9%, 11.5%, 23.1%, 39.2%, 43.9%, and 53.1%, respectively. Compared with the Cr / Au transparent conductive film prepared in Comparative Example 4, the random grid Cr / Au transparent conductive film prepared in this embodiment showed the highest average transmittance improvement of 48.9% in the 0.38µm~2µm range and the highest average transmittance improvement of 50.3% in the 2µm~5µm range. Taking the concentration of SiO2 microsphere dispersion as an example of 2.5 mg / ml, 10 mg / ml, and 20 mg / ml, the transmittance curves of the random grid Cr / Au transparent conductive film prepared in this embodiment and the Cr / Au transparent conductive film prepared in Comparative Example 4 are shown below. Figure 11 As shown.

[0078] Example 6 provides a method for preparing a random grid transparent conductive film using a micro / nano sphere self-assembly mask. The substrate is Corning glass with dimensions of 25 mm (length), 25 mm (width), and 0.7 mm (height). The transparent conductive film is an Au film. To improve the adhesion of the Au film, a transition layer Cr is provided between the Au film and the microsphere template layer. The method specifically includes the following steps:

[0079] Step 1. Using a mixed solvent of anhydrous ethanol and water as a dispersant, SiO2 microspheres were dispersed in the dispersant and ultrasonically dispersed for 2 min to ensure that the microspheres were fully dispersed in the dispersant, thus obtaining a SiO2 microsphere dispersion. The volume ratio of anhydrous ethanol to water was 10:1. The diameters of the SiO2 microspheres were 500 nm, 5 μm, 20 μm, and 30 μm, respectively, and the corresponding concentrations of the SiO2 microsphere dispersions were 2.5 mg / ml, 15 mg / ml, 15 mg / ml, and 25 mg / ml, respectively.

[0080] Step 2. The SiO2 microsphere dispersion is sprayed onto the substrate using an atomization spraying process. The dispersant is allowed to completely evaporate, forming a microsphere template layer. During the spraying process, the spraying amount of the SiO2 microsphere dispersion is 0.24 ml / cm². 2 0.24 ml / cm 2 0.24 ml / cm 2 0.32 ml / cm 2 Spraying parameters: spray gun nozzle diameter is 0.8 mm, spraying distance is 10 cm, spray gun width is 5 cm, air pressure is 20 Psi ~ 45 Psi, spraying speed is 5 ml / min ~ 15 ml / min, ambient humidity is 45% ~ 65%, ambient temperature is 22℃ ~ 28℃.

[0081] Step 3. A 2 nm thick Cr transition layer and a 20 nm thick Au transparent conductive layer are sequentially deposited on the microsphere template layer using magnetron sputtering. During the magnetron sputtering process, the sputtering power is 20 W and the working pressure is 0.6 Pa.

[0082] Step 4. Use a nitrogen gun to blow the sample surface to remove the SiO2 microspheres, and obtain a random grid Cr / Au transparent conductive film.

[0083] The beneficial effects of this embodiment will be explained in detail below with reference to testing, such as... Figure 12The figures show optical microscope images of the microsphere template layer and the random grid Cr / Au transparent conductive film prepared in this embodiment. When the diameter of the SiO2 microspheres is 500 nm, the microsphere template is shown in the upper left figure, and the random grid silver nanowire film is shown in the lower left figure. When the diameter of the SiO2 microspheres is 5 μm, the microsphere template is shown in the upper middle figure, and the random grid silver nanowire film is shown in the lower middle figure. When the diameter of the SiO2 microspheres is 30 μm, the microsphere template is shown in the upper right figure, and the random grid silver nanowire film is shown in the lower right figure. As can be seen from the figures, with the assistance of the spraying process, silica microspheres of different particle sizes self-assemble into dispersed aggregate structures on the surface of the Corning glass substrate. Using these aggregates as microsphere templates, after depositing the Cr / Au transparent conductive film and removing the silica microsphere templates, the Cr / Au transparent conductive film replicates the spatial distribution characteristics of the microsphere templates, forming corresponding void structures. Finally, a Cr / Au transparent conductive film with a random grid structure is prepared on Corning glass.

[0084] When the diameters of the SiO2 microspheres were 500 nm, 5 μm, 20 μm, and 30 μm, the transmittance of the random mesh Cr / Au transparent conductive film prepared in this embodiment at 550 nm was 61%, 68%, 58.1%, and 51.6%, respectively; the sheet resistance was 14.2 ohm / sq, 9.7 ohm / sq, 5.9 ohm / sq, and 4.1 ohm / sq, respectively; and the transmittance at 5 μm was 16.9%, 43.3%, 21.6%, and 12%, respectively. Compared with the Cr / Au transparent conductive film prepared in Comparative Example 4, the random mesh Cr / Au transparent conductive film prepared in this embodiment showed a maximum increase of 40% in average transmittance in the range of 0.38 μm to 2 μm, and a maximum increase of 42.4% in average transmittance in the range of 2 μm to 5 μm. With SiO2 microsphere diameters of 500 nm, 5 μm, 30 μm, and 50 μm, respectively, the results were as follows: Taking μm as an example, the transmittance curves of the random mesh Cr / Au transparent conductive film prepared in this embodiment and the Cr / Au transparent conductive film prepared in Comparative Example 4 are as follows: Figure 13 As shown.

[0085] Example 7 provides a method for preparing a random grid transparent conductive film using a micro / nano sphere self-assembly mask. The substrate is a PET substrate with dimensions of 25 mm (length), 25 mm (width), and 0.7 mm (height). The transparent conductive film is an Au film. To improve the adhesion of the Au film, a transition layer Cr is provided between the Au film and the microsphere template layer. The method specifically includes the following steps:

[0086] Step 1. Using anhydrous ethanol as a dispersant, PS microspheres with a diameter of 10 micrometers were dispersed in the dispersant and ultrasonically dispersed for 2 min to ensure that the micro-nano spheres were fully dispersed in the dispersant, resulting in a PS microsphere dispersion with a concentration of 5 mg / ml.

[0087] Step 2. The PS microsphere dispersion is sprayed onto the substrate using an atomization spraying process, and the dispersant is allowed to completely evaporate to form a microsphere template layer; during the spraying process, the spraying amount of PS microsphere dispersion is 0.32 ml / cm². 2 Spraying parameters: spray gun nozzle diameter is 0.8 mm, spraying distance is 10 cm, spray gun width is 5 cm, air pressure is 20 Psi ~ 45 Psi, spraying speed is 5 ml / min ~ 15 ml / min, ambient humidity is 45% ~ 65%, ambient temperature is 22℃ ~ 28℃.

[0088] Step 3. A 3 nm thick Cr transition layer and a 15 nm thick Au transparent conductive layer are sequentially deposited on the microsphere template layer using magnetron sputtering. During the magnetron sputtering process, the sputtering power is 20 W and the working pressure is 0.6 Pa.

[0089] Step 4. Use a nitrogen gun to blow on the sample surface to remove the PS microspheres, and obtain a random grid Cr / Au transparent conductive film.

[0090] The beneficial effects of this embodiment will be described in detail below with reference to the test. For comparison purposes, Comparative Example 5 is provided here, which is as follows: A Cr transition layer with a thickness of 3 nm and an Au transparent conductive layer with a thickness of 15 nm are sequentially deposited on the substrate using a magnetron sputtering process to form a Cr / Au transparent conductive film. The magnetron sputtering process is the same as step 3.

[0091] like Figure 14 The image shows an optical microscope image of the microsphere template layer and the random grid Cr / Au transparent conductive film prepared in this embodiment. As can be seen from the image, with the assistance of the spraying process, the PS microspheres self-assemble on the surface of the PET substrate to form a dispersed aggregate structure. Using the microsphere template as a template, after depositing the Cr / Au transparent conductive film and removing the microsphere template, the Cr / Au transparent conductive film replicates the spatial distribution characteristics of the microsphere template to form the corresponding void structure. Finally, a Cr / Au transparent conductive film with a random grid structure is prepared on the PET substrate.

[0092] The transmittance at 550 nm of the Cr / Au transparent conductive film prepared in Comparative Example 5 and the random mesh Cr / Au transparent conductive film prepared in this embodiment are 44.8% and 64.1%, respectively, and their sheet resistances are 4.3 ohm / sq and 13.4 ohm / sq, respectively. Compared with the Cr / Au transparent conductive film prepared in Comparative Example 5, the average transmittance of the random mesh Cr / Au transparent conductive film prepared in this embodiment is increased by 28% in the range of 0.38 μm to 2 μm, and by 18.5% in the range of 2 μm to 5 µm. The transmittance curves of the random mesh Cr / Au transparent conductive film prepared in this embodiment and the Cr / Au transparent conductive film prepared in Comparative Example 5 are shown below. Figure 15 As shown.

[0093] In summary, by Figures 2-15 As can be seen, this invention can successfully prepare random grid silver nanowire films, random grid ITO transparent conductive films, and random grid Cr / Au transparent conductive films using a self-assembly masking method of micro / nanospheres. Furthermore, different masking methods can be used to obtain perforated transparent conductive random grid films with different patterns, improving the light transmittance of the transparent conductive film while maintaining low resistance. The improvement effect is more significant in the near-infrared and mid-infrared regions, while simultaneously achieving high transmittance in the visible and infrared bands. As shown in the above embodiments, the perforated random grid silver nanowire films prepared by this invention have a transmittance of over 80% in the visible band, and the transmittance at 5 µm can be increased to 68%, with an average transmittance increase of 27.7% in the 2 µm~5 µm range. The photoelectric properties of the film can also be adjusted by rotating the silver nanowires. The perforated random grid silver nanowire films prepared on PE substrates have an average transmittance increase of 17.1% in the 2 µm~25 µm range; the random grid Cr / Au transparent conductive films have an average transmittance increase of 17.1% in the 0.38 µm~2 µm range. The average transmittance at 1µm was increased from 15% to 64%, and the average transmittance in the 2µm to 55µm range was increased from 1% to 50.1%. This improved the transmittance of the Cr / Au composite film, which was almost opaque at 5µm, to approximately 50%, while maintaining a low sheet resistance of 12.4 ohm / sq. Therefore, this invention not only enables the patterning of transparent conductive films, preparing them into transparent conductive mesh films with random pore structures, but also improves the transmittance of transparent conductive films in the infrared region while maintaining high transmittance and low sheet resistance in the visible region. This achieves the preparation of broadband, high-transmittance, and high-conductivity random mesh transparent conductive films, providing a new approach for the preparation of metal random mesh films and expanding the application range of metal transparent conductive films in the infrared region.

[0094] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A method for preparing a random mesh transparent conductive film by self-assembly of micro-nano spheres, characterized in that, The method comprises the following steps: Step 1. Disperse the micro-nano spheres in a dispersant, and obtain a micro-nano sphere dispersion liquid through ultrasonic dispersion; Step 2. Deposit the micro-nano sphere dispersion liquid on a substrate by using a spray coating process, and wait for the dispersant to completely volatilize to obtain a self-assembled micro-nano sphere template layer; the spray coating parameters are as follows: the spray nozzle aperture of the spray gun is 0.8 mm, the spray distance is 10 cm, the spray gun spray width is 5 cm, the air pressure is 20 Psi-45 Psi, the spray speed is 5 ml / min-15 ml / min, the environmental humidity is 45%-65%, and the environmental temperature is 22°C-28°C; Step 3. Use the self-assembled micro-nano sphere layer as a mask plate to prepare a transparent conductive film layer on the surface of the mask plate; Step 4. Remove the mask plate to obtain a random mesh transparent conductive film.

2. The method according to claim 1, wherein the random mesh transparent conductive film is prepared by self-assembly of the micro-nano spheres. In step 1, the micro-nano spheres are polymer micro-nano spheres or inorganic micro-nano spheres, the polymer micro-nano spheres include polystyrene micro-nano spheres, polymethyl methacrylate micro-nano spheres and polyacrylate micro-nano spheres, and the inorganic micro-nano spheres include silica micro-nano spheres, titanium dioxide micro-nano spheres, magnetite micro-nano spheres, polyvinyl alcohol micro-nano spheres, aluminum oxide micro-nano spheres and glass micro-nano spheres.

3. The method according to claim 1, wherein the random mesh transparent conductive film is prepared by self-assembly of the micro-nano spheres. In step 1, the diameter of the micro-nano spheres is 100 nm-50 µm.

4. The method according to claim 1, wherein the random mesh transparent conductive film is prepared by self-assembly of the micro-nano spheres. In step 1, the dispersant is one or more of water, ethanol, isopropyl alcohol, ethylene glycol, n-butanol, polyethylene glycol, methanol, acetone, ethyl acetate and ethyl lactate.

5. The method according to claim 1, wherein the random mesh transparent conductive film is prepared by self-assembly of the micro-nano spheres. In step 1, the concentration of the micro-nano sphere dispersion liquid is 1 mg / ml-50 mg / ml.

6. The method according to claim 1, wherein the random mesh transparent conductive film is prepared by self-assembly of the micro-nano spheres. In step 2, the substrate is a flexible substrate or a rigid substrate, and includes transparent glass substrates, MgO substrates, MgF2 substrates, ZnS substrates, ZnSe substrates, PET substrates, PE substrates, PMMA substrates, PDMS substrates, PC substrates, PI substrates, PFA substrates, PTFE substrates, COP substrates, PVC substrates, ETFE substrates, quartz substrates and aluminum oxide substrates.

7. The method according to claim 1, wherein the random mesh transparent conductive film is prepared by self-assembly of the micro-nano spheres. In Step 2, the micro- and nano-sphere dispersion liquid is used in an amount of 0.02 ml / cm 2 2 ml / cm 2 .

8. The method according to claim 1, wherein the random mesh transparent conductive film is prepared by self-assembly of the micro-nano spheres. In step 3, the transparent conductive film layer is one or a combination of more than one of oxide films, metal films, nanowire films and conductive polymer films, the oxide films include ITO, IZO, FTO, AZO, GZO and CTO, the metal films include Au, Ag, Cu, Ni, Cr and Ti, and the nanowire films include Cu nanowires, Au nanowires, Al nanowires and Ag nanowires.

9. The method of claim 1, wherein the random mesh transparent conductive film is prepared by self-assembly of the micro-nano spheres. In step 4, the mask plate removal method includes gas gun removal, ultrasonic etching, chemical reaction removal and physical wiping removal.

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