High-transmittance high-conductivity composite, and preparation method and application thereof

Abstract

The application belongs to the technical field of functionalized lighting devices, and particularly relates to a high-transmittance high-conductivity composite as well as a preparation method and application thereof. The high-transmittance high-conductivity composite comprises a PMMA composite and a metal network; wherein the metal network is completely embedded in the PMMA composite. By innovatively adopting a photoetching-evaporation-lifting process, a micron-level metal network is constructed on a thin PMMA layer, so that the network line width can be accurately controlled; meanwhile, a hot-pressing fusion technology is combined to realize interface-free integration of the conductive layer and the PMMA body. This technical scheme effectively solves the compatibility problem between the transmittance and the resistance, successfully realizes excellent performance of transmittance ≥ 85% and resistance ≤ 1 Ω / cm, and provides a new technical approach for the application of functionalized transparent conductive materials in the field of lighting devices.

Description

Technical Field

[0001] This invention belongs to the field of functional lighting device technology, specifically relating to a high-transmittance, high-conductivity composite, its preparation method, and its application. Background Technology

[0002] Traditional technologies face numerous challenges in the application of functionalized transparent conductive materials:

[0003] ITO conductive layer: Indium tin oxide (ITO) conductive layer, as a commonly used transparent conductive material, has obvious defects. It is brittle and easily cracks when subjected to external forces (such as bending, extrusion, etc.), leading to a decrease in conductivity or even failure. In addition, its preparation process is complex and the raw materials required are expensive, resulting in high production costs and limiting its large-scale application.

[0004] Silver nanowire coating process: While conductive layers prepared using the silver nanowire coating process possess a certain degree of conductivity, the difficulty in uniformly distributing the silver nanowires during coating can lead to a significant increase in surface roughness. Excessive surface roughness causes light scattering, severely affecting optical uniformity and reducing the material's light transmittance.

[0005] Screen printing process: When creating conductive patterns using screen printing technology, the line width of the conductive patterns is relatively large due to limitations in printing precision. Wider conductive lines can obstruct the light propagation path, significantly reducing the material's light transmittance and failing to meet the requirements of applications demanding high light transmittance.

[0006] Transfer method: When preparing transparent conductive materials, the transfer method can achieve good patterning effect on planar substrates. However, when dealing with curved substrates, it is difficult to accurately control the pressure, temperature and adhesion during the transfer process, which makes it impossible to achieve high-precision patterning and greatly limits its application in curved optical devices.

[0007] Therefore, it is of great significance to develop a new high-transmittance and high-conductivity composite and study its preparation method. Summary of the Invention

[0008] The technical problem this invention aims to solve is to address the shortcomings of existing technologies and provide a breakthrough over existing technological bottlenecks. By innovatively employing a photolithography-evaporation-lifting process, a micron-level metal network is constructed on a thin-layer PMMA, allowing for precise control of the network linewidth. Simultaneously, combined with thermo-pressing fusion technology, a seamless, integrated conductive layer and the PMMA body are achieved. This technical solution effectively solves the compatibility problem between transmittance and resistance, successfully achieving excellent performance of transmittance ≥85% and resistance ≤1Ω / cm, providing a new technical approach for the application of functionalized transparent conductive materials in lighting devices.

[0009] To address the aforementioned technical problems, this invention discloses a method for preparing a high-transmittance, high-conductivity composite, comprising the following steps:

[0010] S1. Substrate pretreatment: The PMMA sheet after cleaning is activated by oxygen plasma treatment;

[0011] S2. Photolithographic patterning: Photoresist is coated on the surface of the PMMA sheet after S1 pretreatment. After pre-baking, mask exposure is performed, followed by post-baking and development. This forms a photolithographic pattern on the surface of the PMMA sheet that is consistent with the mask pattern.

[0012] S3. Metal vapor deposition: A metal adhesion layer and a metal conductive layer are sequentially vapor deposited on the PMMA sheet after S2 treatment, thus forming a metal network on the surface of the PMMA sheet.

[0013] S4. Lifting and molding: The PMMA sheet treated in S3 is immersed in the release agent, and after cleaning and drying, a PMMA sheet with a metal mesh is obtained.

[0014] S5. Composite preparation: The PMMA sheet with metal mesh obtained in S4 is covered on the surface of the PMMA body, and then hot-pressed and fused in a mold. After cooling, it is demolded to obtain the high light transmittance and high conductivity composite.

[0015] In S1, the PMMA sheet thickness is 20~300 μm; the oxygen plasma treatment has the following process parameters: plasma treatment power of 100~200 W and treatment time of 1~2 min.

[0016] Specifically, in S1, the cleaning process involves immersing the PMMA sheet in isopropanol and ethanol solutions for ultrasonic cleaning, with each solution lasting 15 minutes.

[0017] In S2, the photoresist is a positive photoresist AZ4620 or AZ5214; the coating is spin coating, with specific process parameters of 3000 rpm and a spin coating thickness of 3~4 μm; the mask exposure has the following process parameters: 365 nm ultraviolet light is used for mask exposure, and the exposure amount is set to 200 mJ / cm²; the pre-baking process includes two stages, with the specific steps being: first, baking at 50 ℃ for 2 min, and then raising the temperature to 80 ℃ and baking for 5 min.

[0018] Specifically, the mask exposure uses a mask pattern that is square and / or regular hexagonal.

[0019] In S3, the metal adhesion layer is a Cr adhesion layer; the metal conductive layer includes any one of an Al conductive layer, an Ag conductive layer, and a Cu conductive layer.

[0020] Specifically, the thickness of the metal adhesion layer is 5~100 nm; the thickness of the metal conductive layer is 0.1~2 μm.

[0021] In step S4, the stripping agent includes any one of dimethyl sulfoxide, MicroChem Remover PG, and AZ 400TStripper.

[0022] In S5, the hot-pressing fusion process parameters are: temperature 120~180 ℃, pressure 0.3~5 MPa, and hot-pressing time 10~15 min.

[0023] In S5, the cooling condition is: slow cooling to 70°C.

[0024] Furthermore, the high-transmittance and high-conductivity composite prepared by the above preparation method is also within the scope of protection of this invention; wherein, the high-transmittance and high-conductivity composite includes a PMMA composite and a metal network; the metal network is completely embedded inside the PMMA composite.

[0025] The metal mesh has a line width of 2~20 μm, a mesh aperture of 20~500 μm, and a thickness of 0.1~2.1 μm; the thickness of the metal mesh is the sum of the thicknesses of the metal adhesion layer and the metal conductive layer.

[0026] Furthermore, the application of the aforementioned high-transmittance and high-conductivity composite in the fabrication of optical devices is also within the scope of protection of this invention.

[0027] Specifically, in some embodiments of the present invention, the high-transmittance and high-conductivity composite was prepared by the above-described preparation method. Characterization of its transmittance and resistance properties showed that the high-transmittance and high-conductivity composite provided by the present invention has a transmittance of up to 89% and a resistance of only 0.07 Ω / cm. This demonstrates that the high-transmittance and high-conductivity composite provided by the present invention can be widely used in the manufacture of automotive lighting, special lamps, electromagnetic shielding light-transmitting equipment, and other optical devices with special requirements for light transmittance and conductivity. Beneficial effects

[0028] 1. Interface Fusion Technology: By precisely controlling the hot-pressing temperature, it is kept above the Tg point of PMMA but below its decomposition temperature. During the hot-pressing process, the PMMA molecular chains at the interface gain sufficient energy to begin moving, resulting in interdiffusion. This molecular-level interdiffusion creates a strong bond between the conductive layer and the PMMA matrix, completely eliminating the light scattering problems caused by traditional adhesives and ensuring the high light transmittance and structural stability of the PMMA composite.

[0029] 2. Optical Optimization Design: Mesh Structure Design: Optimize the mesh aperture ratio of the metal conductive network to ≥85%. A larger mesh aperture ratio reduces the metal's obstruction of light, ensuring that light can pass through smoothly.

[0030] 3. Adaptability to irregular curved surfaces: Utilizing the good plasticity of PMMA sheets during hot pressing, when PMMA sheets are hot-pressed and fused with irregularly shaped PMMA bodies, the PMMA sheets can deform according to the curved shape of the mold under the action of the mold, meeting the manufacturing requirements of complex curved irregularly shaped parts.

[0031] 4. Metal Adhesion Layer: When fabricating a metal conductive network on a PMMA sheet, the significant differences in physicochemical properties between the polymer substrate and the metal material (such as surface energy, crystal structure, and coefficient of thermal expansion) can easily lead to weak interfacial bonding when the metal is directly vapor-deposited, resulting in film detachment or conductive network failure. By setting a Cr adhesion layer, Cr exhibits good adhesion to PMMA and subsequently vapor-deposited metal, thereby enhancing the bonding force between the metal conductive network and the PMMA sheet. Attached Figure Description

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0033] Figure 1 The flowchart shows the preparation method of the high-transmittance and high-conductivity composite provided by the present invention; wherein, 1 is a PMMA sheet, 2 is photoresist, 3 is a mask, 4 is a Cr adhesion layer, 5 is a metal conductive layer, 6 is a metal conductive mesh, 7 is the PMMA body, and 8 is the PMMA composite.

[0034] Figure 2 The image shows a SEM image of the metal mesh of a PMMA sheet sample with different Cr adhesion layers prepared in Example 1 of this invention after ultrasonic cleaning. Figure 2 In the image, 'a' represents the surface view of the control group sample without a Cr adhesion layer. Figure 2 b in the image represents the surface of a sample with a 5 nm thick Cr adhesion layer deposited. Figure 2 c in the image represents the surface of a sample with a 50 nm thick Cr adhesion layer deposited on it. Figure 2 In the image, d represents the surface of a sample with a 100 nm thick Cr adhesion layer deposited. Figure 2 In the figure, 'e' represents a cross-sectional view of the control group sample without a Cr adhesion layer. Figure 2 f in the figure represents a cross-sectional view of the sample with a 5 nm thick Cr adhesion layer deposited. Figure 2 In the figure, g represents a cross-sectional view of the sample with a 50 nm thick Cr adhesion layer deposited. Figure 2 In the figure, h represents a cross-sectional view of a sample with a 100 nm thick Cr adhesion layer deposited.

[0035] Figure 3 This is a SEM image of a PMMA sheet sample with a metal mesh in Example 2 of the present invention.

[0036] Figure 4 The light transmittance and electrical resistivity of the PMMA composite prepared in Example 2 of this invention were characterized, wherein, Figure 4 In this context, 'a' represents the light transmittance of the PMMA composite prepared in Example 2. Figure 4 In this context, b represents the resistivity of the PMMA composite prepared in Example 2.

[0037] Figure 5 This is a SEM image of a PMMA sheet sample with a metal mesh in Example 3 of the present invention.

[0038] Figure 6 The light transmittance and electrical resistivity of the PMMA composite prepared in Example 3 of this invention were characterized, wherein, Figure 6 In this context, 'a' represents the light transmittance of the PMMA composite prepared in Example 3. Figure 6 In this context, b represents the resistivity of the PMMA composite prepared in Example 3.

[0039] Figure 7 This is a physical image of the complex curved surface irregular part PMMA composite material prepared in Example 3 of the present invention.

[0040] Figure 8 This is a transmittance characterization diagram of PMMA composites with different aperture ratios of metal networks prepared in Example 4 of the present invention. Detailed Implementation

[0041] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0042] In the following examples, polymethyl methacrylate (PMMA) was purchased from Shanghai McLean Biochemical Technology Co., Ltd.; positive photoresist AZ4620 was purchased from Suzhou Wenhao Microfluidics Technology Co., Ltd.; positive photoresist AZ5214 was purchased from Suzhou Wenhao Microfluidics Technology Co., Ltd.; special stripper MicroChem Remover PG was purchased from MicroChem Corp.; and special stripper AZ 400T Stripper was purchased from AZ Electronic Materials USA Corp.

[0043] This invention provides a high-transmittance, high-conductivity composite and its preparation method. Figure 1The flowchart of the method for preparing a high-transmittance and high-conductivity composite provided by the present invention includes the following steps: S1. Substrate pretreatment: The cleaned PMMA sheet is surface activated by oxygen plasma treatment; S2. Photolithographic patterning: Photoresist is coated on the surface of the PMMA sheet after S1 pretreatment, and after pre-baking, mask exposure is performed, followed by post-baking and development, that is, a photolithographic pattern consistent with the mask pattern is formed on the surface of the PMMA sheet; S3. Metal evaporation: A metal adhesion layer and a metal conductive layer are sequentially evaporated on the PMMA sheet after S2 treatment, that is, a metal network is formed on the surface of the PMMA sheet; S4. Lifting and molding: The PMMA sheet after S3 treatment is immersed in a stripping agent, and after cleaning and drying, a PMMA sheet with a metal mesh is obtained; S5. Composite preparation: The PMMA sheet with a metal mesh obtained in S4 is covered on the surface of the PMMA body, and hot-pressed and fused in a mold. After cooling, it is demolded to obtain the high-transmittance and high-conductivity composite.

[0044] The high-transmittance, high-conductivity composite provided by this invention consists of a PMMA composite and a metal network; the metal network is completely embedded inside the PMMA composite. Specifically, the PMMA composite is formed by hot-pressing and fusing a PMMA sheet and a PMMA body, in which case the metal mesh on the surface of the PMMA sheet forms a metal network that is completely embedded inside the PMMA composite.

[0045] The PMMA composite can be a regular or irregular structure. It mainly serves as the main structure, providing mechanical support and basic optical properties. Its thickness ranges from 0.5 to 10 mm and can be flexibly adjusted according to different application scenarios and product requirements.

[0046] The metal network is fabricated using metallic materials such as Ag, Al, and Cu, with linewidths controlled between 2 and 20 μm and mesh apertures between 20 and 500 μm. This metal network is embedded within the PMMA composite, ensuring high conductivity while minimizing its impact on light propagation, thus achieving high light transmittance. Simultaneously, the PMMA on the surface of the metal network also serves as a support for its fabrication (i.e., a PMMA sheet). During the hot-pressing fusion process, the PMMA sheet with a conductive metal layer is applied to the surface of the shaped PMMA body. After cooling, the PMMA sheet covers the conductive metal layer, effectively protecting the conductive metal network and extending the lifespan of the shaped PMMA composite. Furthermore, since the coating material is the same as the body material, the interface between the materials is eliminated, minimizing the impact on light transmittance. Example 1

[0047] This embodiment provides a method for preparing a high-transmittance, high-conductivity composite, including the following steps:

[0048] Cleaning process: PMMA sheets with a thickness of 30 μm were selected and ultrasonically cleaned sequentially in isopropanol and ethanol solutions for 15 min each. Isopropanol effectively removes contaminants such as grease and organic matter from the surface of the PMMA sheets, while ethanol further cleans and replaces residual acetone, ensuring a clean surface.

[0049] Surface activation: The cleaned PMMA wafers were activated using oxygen plasma treatment (PVA TePla, model GIGABatch 310M). The plasma power was set to 100 W, and the treatment time was 2 min. Oxygen plasma can react with PMMA surface molecules, introducing hydrophilic groups such as hydroxyl groups, significantly improving surface hydrophilicity and enhancing the adhesion between the subsequent photoresist and the PMMA wafer.

[0050] Photoresist spin coating: Select positive photoresist AZ4620 and spin it evenly onto the surface of the pretreated PMMA wafer. Control the spin coating speed to 3000 rpm and the spin coating time to 50 s, so that the photoresist forms a uniform layer with a thickness of about 3 μm under the action of centrifugal force.

[0051] Pre-baking treatment: The PMMA wafer after spin-coating photoresist is pre-baked to remove solvents from the photoresist and stabilize its performance. The pre-baking process consists of two stages: first, baking at 50 ℃ for 2 min to initially remove most of the solvent; then, heating to 80 ℃ and baking for 5 min to further solidify the photoresist and improve the adhesion between the photoresist and the PMMA wafer.

[0052] Mask exposure: 365 nm ultraviolet light was used for mask exposure, with an exposure dose set to 200 mJ / cm². A pre-designed mask with a pattern of square circular holes was used. Exposure caused a photochemical reaction in the photoresist, transferring the mask pattern onto the photoresist layer.

[0053] Post-baking treatment: The exposed PMMA wafers are post-baked at 70 ℃ for 90 s to further promote the cross-linking reaction of the photoresist and improve the resolution and pattern quality of the photoresist.

[0054] Development process: The post-baked PMMA wafer is immersed in AZ4620 photoresist developer for 90 seconds. Under the action of the developer, the unexposed photoresist is dissolved and removed, thereby forming a photoresist pattern on the surface of the PMMA wafer that is consistent with the mask pattern.

[0055] Metal vapor deposition: The developed PMMA sheet is placed in a high-vacuum thermal vapor deposition equipment (TECONO TEMD600), and the vacuum level inside the equipment is increased to 3×10⁻⁶. -6Torr, vacuum, can prevent the metal from reacting with oxygen, water vapor, etc. in the air during the evaporation process, ensuring the quality of the evaporation. Cr adhesion layers with thicknesses of 5 nm, 500 nm, and 100 nm were deposited using a high-vacuum electron beam deposition system. Specific evaporation parameters were: vacuum degree 3 × 10⁻⁶. -6 Torr, evaporation rate 0.1 Å. Then, a 0.2 μm thick Al conductive layer is deposited to form a conductive metal network. Specific evaporation parameters are: vacuum degree 3 × 10⁻⁶. -6 Torr, evaporation rate 0.8 Å; at the same time, a control group was set up. The control group sample did not need to be evaporated to form a Cr adhesion layer, but directly evaporated to form a 0.2 μm thick Al conductive layer to form a conductive metal network.

[0056] Photoresist removal: Immerse the vapor-deposited PMMA wafer in dimethyl sulfoxide (DMSO) at an ultrasonic power of 200 W for 10 min. Remove the photoresist and the overlying metal layer, leaving only the metal portion beneath the photoresist pattern to obtain the desired metal mesh.

[0057] Cleaning and drying: Rinse the PMMA wafer after removing the photoresist with deionized water to remove residual DMSO and impurities on the surface, and then blow it dry with nitrogen to obtain a PMMA wafer with a metal mesh.

[0058] The microstructure of the PMMA sheet samples with metal mesh prepared in this embodiment was characterized using scanning electron microscopy (SEM). The samples were divided into four groups: those without a Cr adhesion layer and those with Cr adhesion layers of 5 nm, 50 nm, and 100 nm thicknesses, respectively. All samples had a 0.2 μm thick Al conductive layer deposited on them and underwent ultrasonic cleaning. Figure 2 The images shown are SEM images of the metal mesh on PMMA sheet samples with different Cr adhesion layers prepared in this embodiment after ultrasonic cleaning. Figure 2 In the image, 'a' represents the surface view of the control group sample without a Cr adhesion layer. Figure 2 b in Figure 2 c and Figure 2 In the diagram, d represents the surface images of samples with 5 nm, 50 nm, and 100 nm thick Cr adhesion layers deposited, respectively. Figure 2 In the figure, 'e' represents a cross-sectional view of the control group sample without a Cr adhesion layer. Figure 2 f in Figure 2 g and Figure 2The 'h' values ​​in the diagram represent cross-sectional views of samples with deposited 5 nm, 50 nm, and 100 nm thick Cr adhesion layers, respectively. The cross-sectional views show the structures of Cr adhesion layers of different thicknesses and a 0.2 μm thick Al conductive layer. The surface views show that in the sample without a Cr adhesion layer (control group), the 0.2 μm thick Al conductive layer significantly detached after ultrasonic cleaning, while in the sample with a Cr adhesion layer, the Al conductive layer remained intact after ultrasonic cleaning. These experimental results demonstrate that by depositing a Cr adhesion layer, Cr exhibits good adhesion to PMMA and subsequently deposited metals, enhancing the bonding force between the metal conductive network and the PMMA sheet. When preparing metal conductive networks on PMMA sheets, the significant differences in physicochemical properties between the polymer substrate and the metal material (such as surface energy, crystal structure, and coefficient of thermal expansion) lead to weak interfacial bonding when directly depositing metal, resulting in film detachment or conductive network failure. Therefore, introducing an intermediate adhesion layer is a key technical approach to improve interfacial bonding. The surface energy of Cr (approximately 590 mN / m) falls between that of PMMA (approximately 34 mN / m) and common conductive metal layers (such as Ag and Au, with surface energies of approximately 1100 mN / m), allowing for thermodynamically stable adsorption by reducing interfacial tension. Furthermore, the microscopically rough interface (roughness Ra < 1 nm) formed by the Cr adhesion layer increases nucleation sites during subsequent metal evaporation, refines the grain size of the conductive layer, and thus improves conductivity (e.g., the conductivity of Ag layers can reach 6.2 × 10⁻⁶). 7 S / m, close to that of bulk materials. Example 2

[0059] This embodiment provides a method for preparing a high-transmittance, high-conductivity composite, including the following steps:

[0060] Cleaning process: PMMA sheets with a thickness of 80 μm were selected and ultrasonically cleaned in isopropanol and ethanol solutions for 15 min each.

[0061] Surface activation: The cleaned PMMA sheet was activated by oxygen plasma treatment (brand PVA TePla, model GIGABatch 310M). The plasma treatment power was set to 200 W and the treatment time was 1 min.

[0062] Photoresist spin coating: Positive photoresist AZ5214 was selected and uniformly spin-coated onto the surface of the pretreated PMMA wafer. The spin coating speed was controlled at 3000 rpm and the time was 60 s, so that the photoresist formed a uniform layer with a thickness of about 3.5 μm under the action of centrifugal force.

[0063] Pre-baking treatment: The PMMA wafer after spin-coating photoresist is pre-baked to remove solvents from the photoresist and stabilize its performance. The pre-baking process consists of two stages: first, baking at 50 ℃ for 2 min to initially remove most of the solvent; then, heating to 80 ℃ and baking for 5 min to further solidify the photoresist and improve the adhesion between the photoresist and the PMMA wafer.

[0064] Mask exposure: 365 nm ultraviolet light was used for mask exposure, with an exposure dose set to 200 mJ / cm². A pre-designed mask with a square grid pattern, a grid line width of 2 μm, and an aperture width of 30 μm (aperture ratio of 87.9%) was used. Exposure caused a photochemical reaction in the photoresist, transferring the mask pattern onto the photoresist layer.

[0065] Post-baking treatment: The exposed PMMA wafers are post-baked at 70 ℃ for 90 s to further promote the cross-linking reaction of the photoresist and improve the resolution and pattern quality of the photoresist.

[0066] Development process: The post-baked PMMA wafer is immersed in AZ5214 photoresist developer for 100 seconds. Under the action of the developer, the unexposed photoresist is dissolved and removed, thereby forming a photoresist pattern on the surface of the PMMA wafer that is consistent with the mask pattern.

[0067] Metal vapor deposition: The developed PMMA sheet is placed in a high-vacuum thermal vapor deposition equipment, and the vacuum level inside the equipment is increased to 3×10⁻⁶ by evacuation. -6 Torr. A 5 nm thick Cr adhesion layer was deposited using a high-vacuum electron beam deposition system. Specific deposition parameters were: vacuum degree 3 × 10⁻⁶. -6 Torr, evaporation rate 0.1 Å. Then, a 0.5 μm thick Ag conductive layer is deposited to form a conductive metal network. Specific evaporation parameters are: vacuum degree 3 × 10⁻⁶. -6 Torr, evaporation rate 0.6 Å.

[0068] Photoresist removal: Immerse the vapor-deposited PMMA wafer in a dedicated stripping agent, MicroChem Remover PG, with an ultrasonic power of 100 W and an immersion time of 10 min. Remove the photoresist and the overlying metal layer, leaving only the metal portion beneath the photoresist pattern to obtain the desired metal mesh.

[0069] Cleaning and drying: Rinse the PMMA wafer after removing the photoresist with deionized water to remove the residual MicroChem Remover PG and impurities on the surface, and then blow it dry with nitrogen to obtain a PMMA wafer with a metal mesh.

[0070] The microstructure of the PMMA sheet with metal mesh prepared in this embodiment was characterized using scanning electron microscopy. Figure 3 This is a SEM image of the PMMA sheet sample with a metal mesh prepared in this embodiment. Figure 3 As can be seen, the structure shown is intact, and the metal mesh has not fallen off or deformed.

[0071] Lamination process: A prepared PMMA sheet with a metal mesh (i.e., the side with the metal mesh) is placed over the surface of the PMMA substrate. The laminated sample is then placed in a hot press mold for hot pressing fusion. The temperature is set to 130 ℃, higher than the glass transition temperature (Tg point, 105 ℃) of PMMA, ensuring sufficient activity of the PMMA molecular chains; the pressure is 0.6 MPa to ensure tight bonding between layers; and the hot pressing time is 15 min to ensure complete interface fusion.

[0072] Cooling and demolding: After hot pressing, the sample is slowly cooled to 70 ℃ to allow the PMMA molecular chains to re-solidify. Then it is demolded to achieve the embedding of the metal conductive network into the irregular PMMA composite, forming an integrated irregular high-transmittance and high-conductivity PMMA composite.

[0073] The transmittance of the PMMA composite prepared in this embodiment was characterized using a UV-Vis spectrometer (Lambda 750, PerkinElmer), and the resistivity of the PMMA composite prepared in this embodiment was measured using a four-probe instrument (Suzhou Jinglü Electronics Co., Ltd.). Figure 4 The light transmittance and electrical resistivity properties of the PMMA composite prepared in this embodiment were characterized. Figure 4 In this example, 'a' represents the light transmittance of the PMMA composite prepared in this embodiment, such as... Figure 4 As shown in a, the light transmittance of the PMMA composite prepared in this embodiment reaches over 89%; Figure 4 In this example, b represents the resistivity of the PMMA composite prepared in this embodiment, such as... Figure 4 As shown in b in the figure, the resistance of the PMMA composite prepared in this embodiment is only 0.3 Ω / cm. Example 3

[0074] This embodiment provides a method for preparing a high-transmittance, high-conductivity composite, including the following steps:

[0075] Cleaning process: Select PMMA sheets with a thickness of 20 μm, and immerse them in isopropanol and ethanol solutions for ultrasonic cleaning, each for 15 min.

[0076] Surface activation: The cleaned PMMA sheet was activated using oxygen plasma treatment (PVA TePla, model GIGABatch 310M). The treatment power was set to 200 W and the treatment time was 1 min.

[0077] Photoresist spin coating: Select positive photoresist AZ4620 and spin it evenly onto the surface of the pretreated PMMA wafer. Control the spin coating speed to 3000 rpm and the time to 60 s, so that the photoresist forms a uniform layer with a thickness of about 3 μm under the action of centrifugal force.

[0078] Pre-baking treatment: The PMMA wafer after spin-coating photoresist is pre-baked to remove solvents from the photoresist and stabilize its performance. The pre-baking process consists of two stages: first, baking at 50 ℃ for 2 min to initially remove most of the solvent; then, heating to 80 ℃ and baking for 5 min to further solidify the photoresist and improve the adhesion between the photoresist and the PMMA wafer.

[0079] Mask exposure: 365nm ultraviolet light was used for mask exposure, with an exposure dose set to 200 mJ / cm². A pre-designed mask with a square grid pattern, a grid line width of 20 μm, and an aperture width of 30 μm (aperture ratio of 36%) was used. Exposure caused a photochemical reaction in the photoresist, transferring the mask pattern onto the photoresist layer.

[0080] Post-baking treatment: The exposed PMMA wafers are post-baked at 70°C for 90 seconds to further promote the cross-linking reaction of the photoresist and improve the resolution and pattern quality of the photoresist.

[0081] Development process: The post-baked PMMA wafer is immersed in AZ4620 photoresist developer for 90 seconds. Under the action of the developer, the unexposed photoresist is dissolved and removed, thereby forming a photoresist pattern on the surface of the PMMA wafer that is consistent with the mask pattern.

[0082] Metal vapor deposition: The developed PMMA sheet is placed in a high-vacuum thermal vapor deposition equipment, and the vacuum level inside the equipment is increased to 3×10⁻⁶ by evacuation. -6 Torr. A 50 nm thick Cr adhesion layer was deposited using a high-vacuum electron beam deposition system. Specific deposition parameters were: vacuum degree 3 × 10⁻⁶. -6 Torr, evaporation rate 0.1 Å. Then, a 2 μm thick Cu conductive layer is deposited to form a conductive metal network. Specific evaporation parameters are: vacuum degree 3 × 10⁻⁶. -6 Torr, evaporation rate 0.7 Å.

[0083] Photoresist removal: Immerse the vapor-deposited PMMA wafer in a dedicated stripping agent, AZ 400T Stripper, with an ultrasonic power of 200 W for 10 minutes. Remove the photoresist and the metal layer covering it, leaving only the metal portion beneath the photoresist pattern to obtain the desired metal mesh.

[0084] Cleaning and drying: Rinse the PMMA wafer after removing the photoresist with deionized water to remove the residual special stripper AZ 400T Stripper and impurities on the surface, and then blow it dry with nitrogen to obtain a PMMA wafer with a metal mesh.

[0085] The microstructure of the PMMA sheet with metal mesh prepared in this embodiment was characterized using scanning electron microscopy. Figure 5 This is a SEM image of the PMMA sheet sample with a metal mesh prepared in this embodiment. Figure 5 As can be seen, the structure shown is intact, and the metal mesh has not fallen off or deformed.

[0086] Overlay process: The prepared PMMA sheet with metal mesh (i.e., the side with the metal mesh) is covered onto the surface of the PMMA body. Then, the overlaid sample is placed in a hot press mold for hot pressing fusion. The temperature is set at 160 ℃, the pressure at 2 MPa, and the hot pressing time at 10 min.

[0087] Cooling and demolding: After hot pressing, the sample is slowly cooled to 70 ℃ to allow the PMMA molecular chains to re-solidify. Then it is demolded to achieve the embedding of the metal conductive network into the irregular PMMA composite, forming an integrated irregular high-transmittance and high-conductivity PMMA composite.

[0088] The transmittance of the PMMA composite prepared in this embodiment was characterized using a UV-Vis spectrometer (Lambda 750, PerkinElmer), and the resistivity of the PMMA composite prepared in this embodiment was measured using a four-probe instrument (Suzhou Jinglü Electronics Co., Ltd.). Figure 6 The light transmittance and electrical resistivity properties of the PMMA composite prepared in this embodiment were characterized. Figure 6 In this example, 'a' represents the light transmittance of the PMMA composite prepared in this embodiment, such as... Figure 6 As shown in a, the light transmittance of the PMMA composite prepared in this embodiment reaches over 40%; Figure 6 In this example, b represents the resistivity of the PMMA composite prepared in this embodiment, such as... Figure 6 As shown in b in the figure, the resistance of the PMMA composite prepared in this embodiment is only 0.07 Ω / cm.

[0089] Figure 7This is a physical image of the complex curved surface irregular part PMMA composite material prepared in this embodiment. As can be seen from the image, the composite material has a semi-circular structure, high transparency, and is completely intact. Example 4

[0090] Referring to the preparation method of Example 3, the light transmittance of the PMMA composite was studied under different aperture ratios by adjusting the opening width of the metal network using different masks.

[0091] Specifically, the metal network prepared according to Example 3 is a Cu network with a linewidth of 20 μm and a thickness of 2 μm, and its aperture ratios are 30%, 40%, 60%, 80%, 85%, 90% and 95%, respectively.

[0092] The transmittance of the PMMA composite prepared in this embodiment was characterized using a UV-Vis spectrometer (Lambda 750, PerkinElmer). Figure 8 This is a characterization of the light transmittance of PMMA composites with different aperture ratios prepared in this embodiment, by... Figure 8 It can be seen that when the aperture ratio is greater than 85%, the light transmittance is higher than 85%, which also proves that the preparation method provided by the present invention can be applied to the preparation of PMMA composites with different aperture ratios.

[0093] This invention provides a high-transmittance, high-conductivity composite, its preparation method, and its application. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing a high-transmittance, high-conductivity composite, characterized in that, Includes the following steps: S1. Substrate pretreatment: The surface of the cleaned PMMA sheet is activated by oxygen plasma treatment; S2. Photolithographic patterning: Photoresist is coated on the surface of the PMMA sheet after S1 pretreatment. After pre-baking, the mask is exposed, followed by post-baking and development. This forms a photolithographic pattern on the surface of the PMMA sheet that is consistent with the mask pattern. S3. Metal vapor deposition: A metal adhesion layer and a metal conductive layer are sequentially vapor deposited on the PMMA sheet after S2 treatment, thus forming a metal network on the surface of the PMMA sheet. S4. Lifting and molding: The PMMA sheet treated in S3 is immersed in the release agent, and after cleaning and drying, a PMMA sheet with a metal mesh is obtained. S5. Composite preparation: The PMMA sheet with metal mesh obtained in S4 is covered on the surface of the PMMA body, and then hot-pressed and fused in a mold. After cooling, it is demolded to obtain the high light transmittance and high conductivity composite. The PMMA sheet and the PMMA body are hot-pressed and fused to form a PMMA composite; the metal network is completely embedded inside the PMMA composite.

2. The preparation method according to claim 1, characterized in that, In S1, the thickness of the PMMA sheet is 20~300 μm; the oxygen plasma treatment has the following process parameters: plasma treatment power of 100~200 W and treatment time of 1~2 min.

3. The preparation method according to claim 1, characterized in that, In S2, the photoresist is a positive photoresist AZ4620 or AZ5214; the coating is spin coating, with specific process parameters of 3000 rpm and a spin coating thickness of 3~4 μm; the mask exposure has the following process parameters: 365 nm ultraviolet light is used for mask exposure, and the exposure amount is set to 200 mJ / cm²; the pre-baking process includes two stages, with the specific steps being: first, baking at 50 ℃ for 2 min, and then raising the temperature to 80 ℃ and baking for 5 min.

4. The preparation method according to claim 3, characterized in that, The mask exposure uses a mask pattern that is square and / or regular hexagonal.

5. The preparation method according to claim 1, characterized in that, In S3, the metal adhesion layer is a Cr adhesion layer; the metal conductive layer includes any one of an Al conductive layer, an Ag conductive layer, and a Cu conductive layer.

6. The preparation method according to claim 5, characterized in that, The thickness of the metal adhesion layer is 5~100 nm; the thickness of the metal conductive layer is 0.1~2 μm.

7. The preparation method according to claim 1, characterized in that, In S5, the hot-pressing fusion process parameters are: temperature 120~180 ℃, pressure 0.3~5 MPa, and hot-pressing time 10~15 min.

8. The high-transmittance, high-conductivity composite prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The high-transmittance, high-conductivity composite comprises a PMMA composite and a metal network; wherein the metal network is completely embedded within the PMMA composite.

9. The high-transmittance, high-conductivity composite according to claim 8, characterized in that, The metal mesh has a line width of 2~20 μm, a mesh aperture of 20~500 μm, and a thickness of 0.1~2.1 μm.

10. The application of the high-transmittance and high-conductivity composite of claim 8 in the fabrication of optical devices.

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