Multi-layer doped flexible structure and preparation method and application thereof

Abstract

The invention discloses a multilayer doped flexible structure and a preparation method and application thereof. According to the method, a quartz flat plate is used as a temporary carrier, PDMS doped with a carbon-based material is spin-coated to form a flexible polymer layer, and after vacuum defoaming and plasma treatment, photoetching and magnetron sputtering are adopted to prepare a patterned metal thin film layer; and transferring the carbon-based thin film attached with the PMMA support, removing the supporting layer, heating and stripping to obtain a laminated thin film capable of being integrally transferred, carrying out plasma treatment on an attaching surface, and attaching the attaching surface to a target curved surface. The obtained structure is formed by stacking the carbon-based thin film layer, the metal pattern layer and the flexible polymer layer, can give consideration to transparency, flexibility and electromagnetic shielding performance, and is suitable for free-form surface transparent electromagnetic shielding.

Description

Technical Field

[0001] This invention belongs to the field of functional composite materials and flexible electronics technology, specifically relating to a multilayer doped flexible structure, its preparation method, and its application. Background Technology

[0002] As electronic devices evolve towards higher frequencies and greater integration, the electromagnetic radiation and interference generated during operation become more prominent. To reduce the impact of electromagnetic radiation on the stability of surrounding equipment and systems, engineering practices typically require the installation of electromagnetic shielding materials or structures in critical areas. In applications such as flexible electronics, wearable devices, and curved surface integration, shielding materials, in addition to possessing a certain shielding effectiveness, are often required to maintain structural and performance stability under attachment, bending, or deformation conditions.

[0003] Among existing electromagnetic shielding materials, metallic materials remain a common technological approach, such as metal foils, metal plates, metal meshes, or metal coatings. These materials typically rely on the high conductivity of metals to generate a reflective shielding effect, which can meet shielding requirements to a certain extent. However, in practical engineering applications, metallic shielding materials generally suffer from poor flexibility, making it difficult to fit complex shapes or areas requiring high adhesion compliance; their high density hinders lightweight design; they pose a risk of corrosion during long-term service or in specific environments, affecting reliability; and their lack of light transmittance makes them unsuitable for scenarios requiring optical windows, display interfaces, or transparent coverage.

[0004] To balance light transmittance and electromagnetic shielding performance, existing solutions have explored technologies such as transparent conductive films, patterned metal mesh layers, carbon-based conductive films, and conductive filler composite polymers. However, transparent conductive films may develop cracks during bending or repeated deformation, leading to a decrease in conductivity and shielding performance. Metal mesh or patterned metal layers require high pattern precision and film continuity while ensuring light transmittance, and their oxidation resistance and environmental resistance are still affected by the material system and structural morphology. Although carbon-based films and composite polymer systems have certain flexibility and light transmittance potential, achieving stable shielding effectiveness, long-term structural reliability, and consistency in large-scale fabrication still presents engineering challenges.

[0005] Therefore, there is an urgent need for a multilayer doped flexible structure, its preparation method, and its application, which can meet the electromagnetic shielding requirements while improving its applicability and reliability in transparent and flexible application scenarios. Summary of the Invention

[0006] This invention provides a multilayer doped flexible structure, its preparation method, and its application, which solves the problems of poor flexibility, high density, easy corrosion, and lack of light transmittance of existing electromagnetic shielding materials.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for preparing a multilayer doped flexible structure, comprising: The quartz plate is cleaned with ethanol and deionized water and then placed on a spin coating equipment. A flexible polymer slurry is drop-added onto the upper surface of the quartz plate and spin-coated to form a flexible polymer layer. Vacuum defoaming is performed on the quartz plate forming the flexible polymer layer to remove air bubbles inside the flexible polymer layer; After heat treatment of the flexible polymer layer, the upper surface of the flexible polymer layer is plasma cleaned. Photoresist is spin-coated onto the upper surface of the flexible polymer layer and then baked to form a photoresist layer. The photoresist layer is exposed, baked, developed, and post-baked using a photomask to form a patterned photoresist layer. The patterned photoresist layer / flexible polymer layer / quartz plate is placed in a magnetron sputtering coating equipment. First, the surface of the photoresist layer is bombarded by an ion source, and then a metal thin film is deposited on it. Remove the photoresist layer to obtain a metal patterned layer / flexible polymer layer / quartz plate; A PMMA-supported carbon-based thin film is attached to the metal pattern layer and heated to form a stacked structure by attaching the carbon-based thin film, the metal pattern layer and the flexible polymer layer. Remove PMMA to obtain carbon-based thin film layer / metal patterned layer / flexible polymer layer / quartz plate; The stacked structure is heated and maintained at a temperature to peel the carbon-based thin film layer / metal pattern layer / flexible polymer layer off the quartz plate, forming a stacked thin film that can be transferred as a whole. The attachment surface of the flexible polymer layer in the peeled laminated film is subjected to plasma cleaning; The attachment surface is attached to the target curved surface to transfer the stacked thin film to the target curved surface and obtain the multilayer doped flexible structure.

[0008] Furthermore, the quartz plate is a double-sided polished, rounded square quartz plate with a thickness of 0.5 mm.

[0009] Furthermore, the doped flexible polymer slurry is a carbon-based material-doped PDMS slurry, wherein the carbon-based material includes multi-walled carbon nanotubes, single-walled carbon nanotubes, single-layer graphene, or multi-layer graphene.

[0010] Furthermore, the spin coating speed for forming the flexible polymer layer is 2000-3000 r / min, and the spin coating time is 60s-100s.

[0011] Furthermore, the vacuum gauge pressure for vacuum defoaming is ≤−0.1 MPa, and the holding time is 15-20 min; the temperature for heating the flexible polymer layer is 85-95 ℃, and the holding time is 15-25 min; the plasma cleaning time for the upper surface of the flexible polymer layer is 8-15 min.

[0012] Furthermore, the formation of the photoresist layer includes: spin coating at a speed of 1500-1800 r / min for 70-90 s and baking at 100-120 ℃ for 15-25 min.

[0013] Furthermore, the formation of the patterned photoresist layer includes: ultraviolet exposure for 110-130 s using a mask, baking at 90-110 ℃ for 10-20 min, developing for 170-190 s, and then baking at 80-100 ℃ for 7-13 min; the metal pattern corresponding to the mask includes rectangular rings, circular rings, triangular rings, or pentagonal rings.

[0014] Furthermore, the temperature is controlled at 80-100 ℃ during the metal thin film deposition; the ion source bombardment time is 8-12 min; and the deposition time using a DC source is 5 min-15 min to form a metal thin film with a thickness of 150-250 nm; the metal of the metal thin film includes Cu, Al, Au or Ag.

[0015] Furthermore, removing the photoresist layer includes immersing the sample in an acetone solution for 35-45 minutes. The step of attaching the PMMA-supported carbon-based film to the metal pattern layer and heating it includes floating the PMMA / carbon-based film on the surface of deionized water to attach the carbon-based film to the metal pattern layer, lifting it out of the water at 45° and then air-drying it at room temperature for 55-65 minutes; after air-drying, baking it at 80-100°C for 25-35 minutes. The removal of PMMA includes soaking in acetone solution for 15-25 minutes; The peeling process involves baking at 100-120 °C for 3-8 min and maintaining the temperature to peel the carbon-based thin film layer / metal pattern layer / flexible polymer layer from the quartz plate. The plasma cleaning of the attachment surface includes bombardment with neon ions for 3-8 minutes.

[0016] Secondly, the present invention provides a multilayer doped flexible structure, comprising a carbon-based thin film layer, a metal pattern layer, and a flexible polymer layer; the metal pattern layer is sandwiched between the carbon-based thin film layer and the flexible polymer layer, the carbon-based thin film layer and the metal pattern layer are attached to each other, and the metal pattern layer and the flexible polymer layer are attached to each other; the flexible polymer layer has an attachment surface located away from the metal pattern layer, the attachment surface being used to transfer and attach the entire stacked thin film composed of the carbon-based thin film layer, the metal pattern layer, and the flexible polymer layer to a target curved surface.

[0017] Thirdly, the present invention provides an application of the above-mentioned multilayer doped flexible structure in flexible transparent electromagnetic shielding, wherein the multilayer doped flexible structure is attached to a free-form surface or a target surface to form a flexible transparent electromagnetic shielding structure.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention uses a quartz plate as a temporary carrier. After spin-coating a flexible polymer layer, a combination of vacuum defoaming, plasma cleaning, photolithography, and magnetron sputtering deposition is introduced. A stacked structure is achieved by transferring and attaching a carbon-based thin film supported by PMMA and removing the support layer. Subsequently, the carbon-based thin film layer / metal pattern layer / flexible polymer layer are peeled off from the quartz plate as a whole using a heat-holding method to form a stacked thin film that can be transferred as a whole. Plasma cleaning of the attachment surface is then used to achieve attachment and transfer to the target curved surface. This process helps to reduce defects caused by bubbles and interface contamination within the layers, improves the reliability and consistency of interlayer attachment, and facilitates the transfer of the thin film structure from the planar preparation stage to curved surface application scenarios.

[0019] The multilayer doped flexible structure of this invention adopts a carbon-based thin film layer / metal patterned layer / flexible polymer layer laminate configuration, which can comprehensively utilize the absorption and shielding characteristics of carbon-based materials and the reflection and shielding characteristics of metal patterned layers to achieve composite shielding. At the same time, the metal patterned layer is sandwiched between the carbon-based thin film layer and the flexible polymer layer, which helps to reduce the direct exposure of the metal layer, thereby improving the oxidation resistance and corrosion resistance. The introduction of a doped flexible polymer layer into the laminate, combined with the control of doping ratio and surface morphology, enables the structure to maintain a certain degree of optical transparency while possessing adhesion, flexibility and bendability, thereby improving the applicability limitations of traditional metal shielding materials, which have poor flexibility, high density and opacity.

[0020] The structure of this invention can be attached to a free-form or target curved surface as a transferable laminated film to form a flexible transparent electromagnetic shielding structure. This application method is beneficial for achieving continuous laying and conformal bonding of the shielding layer on the outer surface of equipment that requires light-transmitting windows or curved surface coverage, expanding the engineering application range of electromagnetic shielding materials in curved and transparent scenarios.

[0021] Of course, implementing the various technical solutions of this invention does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a flowchart of the preparation process in Example 1 of the present invention; Figure 2 This is a schematic diagram of the multilayer doped flexible structure prepared in Example 1 of the present invention; Figure 3 This is a physical image of the multilayer doped flexible structure prepared in Example 1 of the present invention. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0025] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0026] Existing transparent electromagnetic shielding structures mostly employ transparent conductive films, metal mesh patterned layers, or carbon-based conductive films, but face engineering challenges such as performance degradation under bending deformation, insufficient environmental resistance and interface reliability of the patterned layer, and difficulty in ensuring consistent adhesion to curved surfaces. To address these issues, this invention uses a quartz plate as a temporary carrier. Flexible polymer layers are deposited on the planar carrier, and a metal patterned layer and a carbon-based thin film are formed through photolithography and transferred. The stacked structure is then peeled off entirely using a heat-holding method to form a transferable stacked film, which is then transferred and attached to a free-form or target curved surface. This process chain ensures that the metal patterned layer meets the requirements for patterned light transmission while avoiding direct exposure of the metal layer. Furthermore, interface cleaning and activation steps improve interlayer adhesion stability, thereby enhancing the structure's engineering applicability in both transparent and flexible applications.

[0027] Example 1 In this embodiment, the quartz plate is double-sided polished, rounded square, and 0.5 mm thick; the doped flexible polymer slurry is a PDMS slurry doped with multi-walled carbon nanotubes; the metal pattern corresponding to the mask plate is a rectangular ring; the metal thin film is a copper thin film; and the carbon-based thin film is a PMMA-supported carbon-based thin film.

[0028] A method for fabricating a multilayer doped flexible structure includes the following steps: Step S1: Select the quartz plate, place it in an ultrasonic cleaner, clean it with ethanol for 10 minutes, and then clean it with deionized water for 15 minutes; after cleaning, place the quartz plate on a spin coating device.

[0029] Step S2: The doped flexible polymer slurry is dropped onto the upper surface of the quartz plate and spin-coated at a speed of 2100 r / min for 100 s to form a flexible polymer layer.

[0030] Step S3: Place the quartz plate forming the flexible polymer layer in a vacuum defoamer, evacuate to −0.1 MPa and maintain for 15 min to remove air bubbles inside the flexible polymer layer.

[0031] Step S4: Place the vacuum-defoamed flexible polymer layer / quartz plate on a heating stage, heat it to 90 ℃ and keep it for 20 min; then place it in a plasma cleaner and perform plasma cleaning on the upper surface of the flexible polymer layer for 10 min.

[0032] Step S5: Spin-coat photoresist onto the upper surface of the flexible polymer layer at 1600 r / min for 80 s; then bake at 110 ℃ for 20 min to form a photoresist layer.

[0033] Step S6: Expose the photoresist layer to ultraviolet light for 120 s using a rectangular ring mask; then bake at 100 ℃ for 15 min; then develop for 180 s and bake at 90 ℃ for 10 min to form a patterned photoresist layer.

[0034] Step S7: Place the patterned photoresist layer / flexible polymer layer / quartz plate in a magnetron sputtering coating equipment and control the temperature at 90 ℃; first bombard the surface of the photoresist layer with an ion source for 10 min, and then deposit it with a DC source for 15 min to form a copper metal thin film with a thickness of 200 nm.

[0035] Step S8: Remove the photoresist layer by soaking in acetone solution for 40 min to obtain a metal pattern layer / flexible polymer layer / quartz plate, wherein the metal pattern layer is a rectangular ring metal pattern layer.

[0036] Step S9: Float the PMMA-supported carbon-based film on the surface of deionized water to attach the carbon-based film to the metal pattern layer, and lift it out of the water at a 45° angle to make it flat; then air dry at room temperature for 60 min.

[0037] Step S10: Place the dried PMMA-supported carbon-based film / metal pattern layer / flexible polymer layer / quartz plate on a heating table and bake at 90 ℃ for 30 min to allow the carbon-based film, metal pattern layer and flexible polymer layer to adhere and form a laminated structure.

[0038] Step S11: Remove PMMA by soaking in acetone solution for 20 min to obtain carbon-based thin film layer / metal patterned layer / flexible polymer layer / quartz plate.

[0039] Step S12: Bake the carbon-based thin film layer / metal pattern layer / flexible polymer layer / quartz plate at 110 °C for 5 min, and peel the carbon-based thin film layer / metal pattern layer / flexible polymer layer from the quartz plate while maintaining the temperature to form a stacked film that can be transferred as a whole.

[0040] Step S13: Place the peeled laminated film in a plasma cleaner and bombard the attachment surface of the flexible polymer layer with neon ions for 5 minutes.

[0041] Step S14: The plasma-cleaned attachment surface is attached to the target curved surface to complete the fabrication of the multilayer doped flexible structure.

[0042] In the above steps, the vacuum defoaming of the flexible polymer layer in step S3 is mainly used to reduce the internal bubble defects formed by air entrainment during spin coating, which is beneficial to the surface consistency of subsequent photolithography and metal thin film deposition, and provides a more stable foundation for the bonding of the stacked interface.

[0043] In steps S4 and S13, plasma cleaning is performed on the upper surface / attachment surface of the flexible polymer layer, mainly to remove interface contaminants and improve surface activity, thereby improving the adhesion reliability between the metal pattern layer and the flexible polymer layer, as well as between the stacked film and the target curved surface. In conjunction with this, in step S7, the surface of the photoresist layer is bombarded with an ion source before magnetron sputtering, which can be used to improve the interface bonding state during subsequent metal film deposition, making the metal pattern layer formation process more stable.

[0044] In steps S9 to S11, the carbon-based thin film supported by PMMA is transferred, attached, and then the PMMA is removed. This allows for the formation of a carbon-based thin film layer / metal pattern layer / flexible polymer layer stacked structure while facilitating the control of the carbon-based thin film spreading and attachment process. Combined with the heating and temperature-maintaining peeling in step S12, the carbon-based thin film layer / metal pattern layer / flexible polymer layer can be peeled off from the quartz plate as a whole to form a stacked film that can be transferred as a whole, thus providing a process basis for subsequent attachment to the target curved surface.

[0045] See Figure 2 , Figure 2 This is a schematic diagram of the multilayer doped flexible structure prepared by the method of this embodiment. The structure includes a carbon-based thin film layer, a metal patterned layer, and a flexible polymer layer, wherein the metal patterned layer is formed by photolithography and sandwiched between the carbon-based thin film layer and the flexible polymer layer. Figure 2 As shown in the structure, electromagnetic radiation first passes through the carbon-based thin film layer, where the carbon-based material absorbs and loses the electromagnetic radiation. Unabsorbed electromagnetic radiation continues into the metal pattern layer. The periodic structure and elemental composition of the metal pattern layer are controllable, causing the electromagnetic radiation to be reflected and forming a reflection shielding effect. The remaining electromagnetic radiation further enters the flexible polymer layer, where absorption and reflection are again achieved through the control of the doping ratio and surface morphology. Based on this layered mechanism, the multilayer doped flexible structure, while possessing the basic electromagnetic shielding structure, can also achieve flexibility and bendability. Simultaneously, the metal pattern layer has oxidation resistance and can meet light transmittance requirements under patterned conditions, while the carbon-based thin film layer and flexible polymer layer also have a certain optical transmittance. This allows the structure to be attached to free-form surfaces and used in applications that combine electromagnetic shielding and optical transparency.

[0046] Figure 3 This is a photograph of the multilayered doped flexible structure prepared in this embodiment. The sample is a sheet-like stacked thin film in an arc-shaped curved state, and a relatively uniform mesh-like texture is visible on the film surface. Figure 3As can be seen, the sample maintains a continuous film appearance even under this curved shape, with no obvious cracks, severe wrinkles, or large-area delamination observed, indicating a certain degree of adhesion stability between the carbon-based film layer, the metal pattern layer, and the flexible polymer layer. Simultaneously, the sample maintains its overall shape during clamping and handling, demonstrating its flexibility and maneuverability. This facilitates subsequent overall transfer and attachment to the target curved surface, and meets the mechanical compliance requirements of curved surface covering applications.

[0047] Example 2: The difference between this embodiment and Embodiment 1 is that: the doped flexible polymer slurry is a PDMS slurry doped with single-walled carbon nanotubes; the metal pattern corresponding to the mask is a ring; the metal film is an aluminum film; and some process parameters are adjusted accordingly, while the remaining steps and parameters are the same as in Embodiment 1.

[0048] Step S2: Drop PDMS slurry doped with single-walled carbon nanotubes onto the surface of a quartz plate and spin-coat at 2100 r / min for 80 s to form a flexible polymer layer.

[0049] Step S6: Expose the photoresist layer to ultraviolet light for 120 s using a circular mask, then bake at 100 ℃ for 15 min, develop for 180 s, and then bake at 90 ℃ for 10 min to form a patterned photoresist layer.

[0050] Step S7: First, bombard the aluminum metal film with an ion source for 10 minutes in a magnetron sputtering coating equipment, and then deposit it with a DC source for 10 minutes to form an aluminum metal film with a thickness of 200 nm.

[0051] Step S8: Remove the photoresist layer by soaking in acetone solution for 40 min to obtain a circular metal pattern layer / flexible polymer layer / quartz plate.

[0052] Example 3: The difference between this embodiment and Embodiment 1 is that: the doped flexible polymer slurry is a single-layer graphene-doped PDMS slurry; the metal pattern corresponding to the mask is a triangular ring; the metal film is a gold film; and some process parameters are adjusted accordingly, while the remaining steps and parameters are the same as in Embodiment 1.

[0053] Step S2: A single layer of graphene-doped PDMS slurry is dropped onto the surface of a quartz plate and spin-coated at 2100 r / min for 60 s to form a flexible polymer layer.

[0054] Step S6: Expose the photoresist layer to ultraviolet light for 120 s using a triangular ring mask, then bake at 100 ℃ for 15 min, develop for 180 s, and then bake at 90 ℃ for 10 min to form a patterned photoresist layer.

[0055] Step S7: First, bombard the gold film with an ion source for 10 minutes in a magnetron sputtering coating equipment, and then deposit it with a DC source for 5 minutes to form a gold film with a thickness of 200 nm.

[0056] Step S8: Immerse in acetone solution for 40 min to remove the photoresist layer, obtaining a triangular ring metal pattern layer / flexible polymer layer / quartz plate.

[0057] Example 4: This embodiment follows the same process route as Embodiment 1, except that: the doped flexible polymer slurry is a PDMS slurry doped with single-walled carbon nanotubes, the metal pattern corresponding to the mask is a ring, the metal film is an Al metal film, and the carbon-based film is a carbon nanotube film; at the same time, some process parameters are adjusted accordingly, and the remaining steps are the same as in Embodiment 1.

[0058] A method for fabricating a multilayer doped flexible structure includes the following steps: Step S1: After cleaning with ethanol and deionized water, place the product on a spin coating device. The cleaning method is the same as in Example 1.

[0059] Step S2: Spin coat at 2000 r / min for 60 s to form a flexible polymer layer.

[0060] Step S3: Evacuate to −0.1 MPa and maintain for 15 min to complete vacuum defoaming.

[0061] Step S4: After heating at 85 °C for 15 min, perform plasma cleaning on the upper surface of the flexible polymer layer for 8 min.

[0062] Step S5: Spin coat at 1500 r / min for 70 s and bake at 100 ℃ for 15 min to form a photoresist layer.

[0063] Step S6: Expose the photomask to ultraviolet light for 110 s, bake at 90 ℃ for 10 min, develop for 170 s, and then bake at 80 ℃ for 7 min to form a patterned photoresist layer.

[0064] Step S7: During magnetron sputtering deposition, the temperature is controlled at 80 ℃; ion source bombardment for 8 min; DC source deposition for 5 min to form an Al metal thin film with a thickness of 150 nm.

[0065] Step S8: Remove the photoresist layer by soaking in acetone solution for 35 min to obtain a circular metal pattern layer / flexible polymer layer / quartz plate.

[0066] Step S9: Float the PMMA / carbon-based film on the surface of deionized water to allow the carbon-based film to adhere to the metal pattern layer, and then lift it out of the water at a 45° angle and air dry at room temperature for 55 min.

[0067] Step S10: Bake at 80 °C for 25 min to allow the carbon-based thin film, metal pattern layer and flexible polymer layer to adhere and form a laminated structure.

[0068] Step S11: Remove PMMA by soaking in acetone solution for 15 min.

[0069] Step S12: Bake at 100 °C for 3 min and maintain the temperature to peel the carbon-based thin film layer / metal pattern layer / flexible polymer layer from the quartz plate to form a stacked film that can be transferred as a whole.

[0070] Step S13: Use neon ions to bombard the attachment surface of the flexible polymer layer in the laminated film for 3 min to perform plasma cleaning.

[0071] Step S14: Attach the attachment surface to the target curved surface to obtain a multilayer doped flexible structure.

[0072] Example 5 This embodiment follows the same process route as Embodiment 1, except that: the doped flexible polymer slurry is a multilayer graphene-doped PDMS slurry, the metal pattern corresponding to the mask is a pentagonal ring, the metal film is a Cu metal film, and the carbon-based film is a graphene film; at the same time, some process parameters are adjusted accordingly, and the remaining steps are the same as in Embodiment 1.

[0073] A method for fabricating a multilayer doped flexible structure includes the following steps: Step S1: The cleaning method is the same as in Example 1.

[0074] Step S2: Spin coat at 3000 r / min for 100 s to form a flexible polymer layer.

[0075] Step S3: Evacuate to −0.1 MPa and maintain for 20 min to complete vacuum defoaming.

[0076] Step S4: After heating at 95 °C for 25 min, perform plasma cleaning on the upper surface of the flexible polymer layer for 15 min.

[0077] Step S5: Spin coat at 1800 r / min for 90 s and bake at 120 ℃ for 25 min to form a photoresist layer.

[0078] Step S6: Expose the photomask to ultraviolet light for 130 s, bake at 110 ℃ for 20 min, develop for 190 s, and then bake at 100 ℃ for 13 min to form a patterned photoresist layer.

[0079] Step S7: During magnetron sputtering deposition, the temperature is controlled at 100 ℃; ion source bombardment for 12 min; DC source deposition for 15 min to form a Cu metal thin film with a thickness of 250 nm.

[0080] Step S8: Immerse in acetone solution for 45 min to remove the photoresist layer, and obtain a pentagonal ring metal pattern layer / flexible polymer layer / quartz plate.

[0081] Step S9: Float the PMMA / carbon-based film on the surface of deionized water to allow the carbon-based film to adhere to the metal pattern layer, and then lift it out of the water at a 45° angle and air dry at room temperature for 65 minutes.

[0082] Step S10: Bake at 100 °C for 35 min to allow the carbon-based thin film, the metal pattern layer, and the flexible polymer layer to adhere and form a laminated structure.

[0083] Step S11: Remove PMMA by soaking in acetone solution for 25 min.

[0084] Step S12: Bake at 120 °C for 8 min and maintain the temperature to peel the carbon-based thin film layer / metal pattern layer / flexible polymer layer from the quartz plate to form a stacked film that can be transferred as a whole.

[0085] Step S13: Use neon ions to bombard the attachment surface of the flexible polymer layer in the laminated film for 8 min to perform plasma cleaning.

[0086] Step S14: Attach the attachment surface to the target curved surface to obtain a multilayer doped flexible structure.

[0087] Example 6 This embodiment follows the same process route as Embodiment 1, except that: the doped flexible polymer slurry is a single-layer graphene-doped PDMS slurry, the metal pattern corresponding to the mask is a triangular ring, the metal film is an Au metal film, and the carbon-based film is a graphene film; at the same time, some process parameters are adjusted accordingly, and the remaining steps are the same as in Embodiment 1.

[0088] A method for fabricating a multilayer doped flexible structure includes the following steps: Step S1: The cleaning method is the same as in Example 1.

[0089] Step S2: Spin coat at 2500 r / min for 80 s to form a flexible polymer layer.

[0090] Step S3: Evacuate to −0.1 MPa and maintain for 18 min to complete vacuum defoaming.

[0091] Step S4: After heating at 90 °C for 20 min, perform plasma cleaning on the upper surface of the flexible polymer layer for 12 min.

[0092] Step S5: Spin coat at 1650 r / min for 80 s and bake at 110 ℃ for 20 min to form a photoresist layer.

[0093] Step S6: Expose the photomask to ultraviolet light for 120 s, bake at 100 ℃ for 15 min, develop for 180 s, and then bake at 90 ℃ for 10 min to form a patterned photoresist layer.

[0094] Step S7: During magnetron sputtering deposition, the temperature is controlled at 90 °C; ion source bombardment for 10 min; DC source deposition for 10 min to form an Au metal thin film with a thickness of 200 nm.

[0095] Step S8: Immerse in acetone solution for 40 min to remove the photoresist layer, obtaining a triangular ring metal pattern layer / flexible polymer layer / quartz plate.

[0096] Step S9: Float the PMMA / carbon-based film on the surface of deionized water to allow the carbon-based film to adhere to the metal pattern layer, and then lift it out of the water at 45° and air dry at room temperature for 60 min.

[0097] Step S10: Bake at 90 °C for 30 min to allow the carbon-based thin film, metal pattern layer and flexible polymer layer to adhere and form a laminated structure.

[0098] Step S11: Remove PMMA by soaking in acetone solution for 20 min.

[0099] Step S12: Bake at 110 °C for 5 min and maintain the temperature to peel the carbon-based thin film layer / metal pattern layer / flexible polymer layer from the quartz plate to form a stacked film that can be transferred as a whole.

[0100] Step S13: Perform plasma cleaning on the attached surface by bombarding with neon ions for 5 minutes.

[0101] Step S14: Attach the attachment surface to the target curved surface to obtain a multilayer doped flexible structure.

[0102] Example 7 This embodiment provides a multilayer doped flexible structure, which is composed of a carbon-based thin film layer, a metal patterned layer, and a flexible polymer layer. The metal patterned layer is sandwiched between the carbon-based thin film layer and the flexible polymer layer, and the carbon-based thin film layer and the metal patterned layer are attached and connected. The flexible polymer layer is a doped flexible polymer layer, and the doped flexible polymer paste can be a PDMS paste doped with a carbon-based material, such as multi-walled carbon nanotubes, single-walled carbon nanotubes, single-layer graphene, or multi-layer graphene. The metal patterned layer is a patterned metal thin film formed by photolithography. The metal thin film can be Cu, Al, Au, or Ag, and its thickness can be 150 nm-250 nm. The metal pattern can be a rectangular ring, a circular ring, a triangular ring, or a pentagonal ring. The flexible polymer layer has an attachment surface located away from the metal pattern layer. After plasma cleaning, the attachment surface is used to transfer and attach the entire stacked film composed of the carbon-based thin film layer / metal pattern layer / flexible polymer layer to the target curved surface.

[0103] Example 8 This embodiment provides the application of the multilayer doped flexible structure in flexible transparent electromagnetic shielding. Specifically, after removing the transferable stacked film prepared in Examples 1-6, the attachment surface of the flexible polymer layer is used as the contact interface with the object to be attached. The attachment surface is plasma cleaned to improve the attachment stability. Subsequently, the attachment surface is attached to a free-form surface or a target surface, so that the stacked film is transferred to cover the surface of the free-form surface or the target surface, forming a flexible transparent electromagnetic shielding structure. Since the stacked film is composed of a carbon-based thin film layer / metal pattern layer / flexible polymer layer, the carbon-based thin film layer and the metal pattern layer work together to form a composite shielding path, and the flexible polymer layer provides flexibility and attachment capability, so that the structure can achieve electromagnetic shielding in areas requiring light transmission coverage and is suitable for curved surface attachment applications. Furthermore, the multilayer doped flexible structure can be applied to scenarios such as 5G communication, Internet of Things, medical devices, aerospace, security protection, precision instruments, consumer electronics, and drones to meet the application requirements of flexible transparent electromagnetic shielding structures under free-form surface conditions.

[0104] Furthermore, although the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in sequential order. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

Claims

1. A method for preparing a multilayer doped flexible structure, characterized in that, include: The quartz plate is cleaned with ethanol and deionized water and then placed on a spin coating equipment. A flexible polymer slurry is drop-added onto the upper surface of the quartz plate and spin-coated to form a flexible polymer layer. Vacuum defoaming is performed on the quartz plate forming the flexible polymer layer to remove air bubbles inside the flexible polymer layer; After heat treatment of the flexible polymer layer, the upper surface of the flexible polymer layer is plasma cleaned. Photoresist is spin-coated onto the upper surface of the flexible polymer layer and then baked to form a photoresist layer. The photoresist layer is exposed, baked, developed, and post-baked using a photomask to form a patterned photoresist layer. The patterned photoresist layer / flexible polymer layer / quartz plate is placed in a magnetron sputtering coating equipment. First, the surface of the photoresist layer is bombarded by an ion source, and then a metal thin film is deposited on it. Remove the photoresist layer to obtain a metal patterned layer / flexible polymer layer / quartz plate; A PMMA-supported carbon-based thin film is attached to the metal pattern layer and heated to form a stacked structure by attaching the carbon-based thin film, the metal pattern layer and the flexible polymer layer. Remove PMMA to obtain carbon-based thin film layer / metal patterned layer / flexible polymer layer / quartz plate; The stacked structure is heated and maintained at a temperature to peel the carbon-based thin film layer / metal pattern layer / flexible polymer layer off the quartz plate, forming a stacked thin film that can be transferred as a whole. The attachment surface of the flexible polymer layer in the peeled laminated film is subjected to plasma cleaning; The attachment surface is attached to the target curved surface to transfer the stacked thin film to the target curved surface and obtain the multilayer doped flexible structure.

2. The method for preparing a multilayer doped flexible structure according to claim 1, characterized in that, The doped flexible polymer slurry is a PDMS slurry doped with carbon-based materials, including multi-walled carbon nanotubes, single-walled carbon nanotubes, single-layer graphene, or multi-layer graphene.

3. The method for preparing a multilayer doped flexible structure according to claim 1, characterized in that, The spin coating speed for forming the flexible polymer layer is 2000-3000 r / min, and the spin coating time is 60 s-100 s.

4. The method for preparing a multilayer doped flexible structure according to claim 1, characterized in that, The vacuum defoaming process has a vacuum gauge pressure ≤ −0.1 MPa and a holding time of 15-20 min; the heating treatment of the flexible polymer layer is performed at a temperature of 85-95 ℃ and a holding time of 15-25 min; the plasma cleaning of the upper surface of the flexible polymer layer is performed for 8-15 min.

5. The method for preparing a multilayer doped flexible structure according to claim 1, characterized in that, The formation of the photoresist layer includes: spin coating at a speed of 1500-1800 r / min for 70-90 s and baking at 100-120 ℃ for 15-25 min.

6. The method for preparing a multilayer doped flexible structure according to claim 1, characterized in that, The formation of the patterned photoresist layer includes: UV exposure for 110-130 s using a photomask, baking at 90-110 ℃ for 10-20 min, developing for 170-190 s, and then baking at 80-100 ℃ for 7-13 min; the metal pattern corresponding to the photomask includes rectangular rings, circular rings, triangular rings, or pentagonal rings.

7. The method for preparing a multilayer doped flexible structure according to claim 1, characterized in that, The temperature is controlled at 80-100 ℃ during the metal thin film deposition process; the ion source bombardment time is 8-12 min; the DC source deposition time is 5 min-15 min to form a metal thin film with a thickness of 150-250 nm; the metal of the metal thin film includes Cu, Al, Au or Ag.

8. The method for preparing a multilayer doped flexible structure according to claim 1, characterized in that, Removing the photoresist layer involves immersing the sample in an acetone solution for 35-45 minutes. The step of attaching the PMMA-supported carbon-based film to the metal pattern layer and heating it includes floating the PMMA / carbon-based film on the surface of deionized water to attach the carbon-based film to the metal pattern layer, lifting it out of the water at 45° and then air-drying it at room temperature for 55-65 minutes; after air-drying, baking it at 80-100°C for 25-35 minutes. The removal of PMMA includes soaking in acetone solution for 15-25 minutes; The peeling process involves baking at 100-120 °C for 3-8 min and maintaining the temperature to peel the carbon-based thin film layer / metal pattern layer / flexible polymer layer from the quartz plate. The plasma cleaning of the attachment surface includes bombardment with neon ions for 3-8 minutes.

9. A multilayer doped flexible structure, characterized in that, The material comprises a carbon-based thin film layer, a metal pattern layer, and a flexible polymer layer; the metal pattern layer is sandwiched between the carbon-based thin film layer and the flexible polymer layer, and the carbon-based thin film layer is attached to the metal pattern layer and the metal pattern layer is attached to the flexible polymer layer; the flexible polymer layer has an attachment surface located away from the metal pattern layer, and the attachment surface is used to transfer and attach the entire stacked film composed of the carbon-based thin film layer, the metal pattern layer, and the flexible polymer layer to the target curved surface.

10. The application of the multilayer doped flexible structure according to claim 9 in flexible transparent electromagnetic shielding, characterized in that, The multilayer doped flexible structure is attached to a free-form surface or a target surface to form a flexible transparent electromagnetic shielding structure.

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