A diaphragm and a method of manufacturing the same

Abstract

The application provides a crystal membrane screen and a preparation method thereof. The preparation method comprises the following steps: performing a hydroxylation treatment on the surface of a flexible transparent substrate to obtain a hydroxylated substrate; constructing a transparent conductive circuit on the hydroxylated substrate; electrically connecting a light-emitting chip to the substrate with the transparent conductive circuit through a conductive connecting material; and packaging the obtained substrate to form a protective layer on the surface of the substrate to obtain the crystal membrane screen. A regular array of metal nanodots is prepared on the surface of the substrate in advance through a spherical template method. When a composite coating liquid is subsequently scraped and coated, the nanosilver wires are orderly distributed with the array as a "skeleton" to form a regular conductive network, thereby avoiding local sheet resistance differences caused by traditional random lapping and significantly improving the uniformity of the large-area conductive film.

Description

Technical Field

[0001] This invention relates to the technical field of crystal film screens, and particularly to a crystal film screen and its preparation method. Background Technology

[0002] As a flexible transparent display device, one of the key aspects of a crystal film screen is its high-performance transparent conductive circuitry. Traditional indium tin oxide (ITO) is difficult to use on flexible substrates due to its brittleness, poor flexibility, and the need for high-temperature fabrication. Silver nanowires (AgNW) are considered an ideal alternative material due to their good conductivity, high light transmittance, and excellent flexibility; however, current transparent conductive films based on silver nanowires still face the following problems: Random splicing of silver wires leads to large differences in local sheet resistance, affecting the conductivity uniformity of large-size screens.

[0003] The silver wires are only in physical contact, resulting in high contact resistance and easy separation when bent.

[0004] The silver wires have weak adhesion to the substrate and are prone to oxidation or sulfidation, resulting in performance degradation.

[0005] Traditional photolithography etching can easily damage silver lines and makes it difficult to selectively protect the pad area, which is not conducive to subsequent chip connection. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a crystal film screen and its preparation method.

[0007] The invention provides the following technical solution: In a first aspect, a method for preparing a crystal film screen is provided, comprising the following steps: A hydroxylated substrate is obtained by hydroxylating the surface of a flexible transparent substrate. Constructing transparent conductive lines on the hydroxylated substrate; the construction of transparent conductive lines includes the following steps: A one-pot polyol method was used to synthesize a dispersion of silver nanowires. A regularly arranged metal nanoarray was prepared on the surface of the hydroxylated substrate using a removable spherical template method. The nano-silver wire dispersion, the conductive polymer aqueous solution, and the surfactant are mixed to prepare a composite coating solution. The composite coating liquid is applied onto a substrate with a metal nano-array using a blade coating method to form a conductive polymer / conductive nanowire composite layer. The conductive polymer / conductive nanowire composite layer is subjected to low-temperature fusion welding to cause local fusion welding between the silver nanowires and between the silver nanowires and the metal nanolattice. Then, a transparent metal oxide precursor liquid is coated by a blade coating method, and a transparent metal oxide top layer is formed by heat treatment to obtain a three-layer composite conductive film. The three-layer composite conductive film is patterned to form a circuit pattern, and the transparent metal oxide layer in the pad area is selectively removed to expose the underlying conductive nanowire network, resulting in a substrate with transparent conductive lines. The light-emitting chip is electrically connected to the substrate with transparent conductive lines via a conductive connecting material. The obtained substrate is encapsulated to form a protective layer on its surface, resulting in a crystal film screen.

[0008] Furthermore, the specific steps for hydroxylation treatment of the flexible transparent substrate surface include: The flexible transparent substrate was ultrasonically cleaned in acetone, anhydrous ethanol and deionized water in sequence. The cleaned substrate is immersed in a mixed solution of ammonia and hydrogen peroxide at a volume ratio of (1-4):1, and heated and stirred at 70°C-90°C for 1-2 hours. Then it is rinsed with deionized water, dried with nitrogen, and then irradiated in an ultraviolet-ozone cleaner for 5-15 minutes to obtain a hydroxylated substrate.

[0009] Furthermore, the specific steps for synthesizing the silver nanowire dispersion using the one-pot polyol method include: Add the following solutions to the reaction vessel at once: silver nitrate solution, polyvinylpyrrolidone solution, ethylene glycol, sodium chloride solution, and sodium bromide solution to obtain a mixture; After the mixture is stirred evenly, it is heated to react, and the reaction temperature is controlled at 130°C–150°C. Nitrogen gas was continuously introduced during the reaction to remove oxygen, and the mixture was stirred. The reaction time was 1.5h–2.5h. After the reaction is complete, allow it to cool naturally to room temperature, add anhydrous ethanol to dilute, shake thoroughly to disperse the product, then centrifuge, discard the supernatant, add ethanol to the precipitate, sonicate for 5-10 minutes, centrifuge again, and repeat the centrifugation-dispersion operation 3 times. Finally, the washed precipitate was redispersed in anhydrous ethanol to obtain a dispersion of silver nanowires.

[0010] Furthermore, the specific steps for preparing a regularly arranged metal nanoarray on the surface of the hydroxylated substrate using a removable spherical template method include: Polystyrene microspheres with an average diameter of 1.0 μm to 2.5 μm were used to prepare an aqueous dispersion with a solid content of 0.5 wt% to 5 wt% using deionized water; The aqueous dispersion is dropped onto the surface of the hydroxylated substrate and left to stand for 10 min to 60 min, so that the microspheres self-assemble to form a single layer of closely packed hexagonal template. A substrate with a polystyrene microsphere template was placed in a vacuum sputtering coating machine, and a vacuum of 5 × 10⁻⁶ was applied. - ³Pa~1×10 - ²Pa, introduce high-purity argon gas, adjust the working gas pressure to 0.5Pa~2Pa, set the sputtering current to 5mA~20mA, and the sputtering time to 30s~120s, deposit a 20nm~30nm silver film in the gap between the microspheres, and keep the substrate temperature below 50°C during the sputtering process; The sample with deposited silver film was sequentially immersed in dichloromethane and ultrasonically vibrated for 2 min to 10 min, then immersed in acetone and ultrasonically vibrated for 2 min to 10 min, then rinsed with anhydrous ethanol or deionized water for 1 min to 2 min, and finally dried with nitrogen to remove polystyrene microspheres, forming a silver dot matrix on the substrate surface consisting of triangular silver particles arranged in a hexagonal pattern, thus obtaining a silver dot matrix film.

[0011] Furthermore, the specific steps for mixing the silver nanowire dispersion, the conductive polymer aqueous solution, and the surfactant to prepare the composite coating solution are as follows: The nano-silver wire dispersion was mixed with PEDOT:PSS aqueous solution at a volume ratio of 1:3, a fluorocarbon surfactant was added, and the viscosity was adjusted to 50 cP-200 cP with ethylene glycol or dimethyl sulfoxide, and the mixture was thoroughly mixed.

[0012] Furthermore, the specific steps for applying the composite coating liquid onto a substrate with a metal nanoarray using a blade coating method to form a conductive polymer / conductive nanowire composite layer are as follows: The silver dot matrix film is flattened and fixed on the heating table of the automatic coating machine, and the temperature of the heating table is set to 55°C-75°C; the gap between the doctor blade and the film surface is adjusted to 80μm-120μm; 0.3mL-0.8mL of composite coating liquid is taken and evenly injected onto the film in front of the doctor blade; the coating machine is started, and the doctor blade moves at a constant speed to spread the coating liquid into a wet film; The coated film is transferred to a heating platform for heat treatment to allow the solvent to evaporate and the film to cure. After cooling to room temperature, the film is immersed in anhydrous methanol and pulled up and down to remove the PSS component; the film is then removed and dried. Repeat the above "coating-heat treatment-methanol pulling-drying" process at least once to obtain a thin film with a PEDOT:PSS / silver nanowire composite layer as the bottom layer.

[0013] Furthermore, the specific steps for performing low-temperature fusion welding on the conductive polymer / conductive nanowire composite layer are as follows: The dried composite layer is placed in a vacuum drying oven, evacuated to -0.08MPa to -0.1MPa, heated to 180°C to 200°C, held for 20 to 40 minutes, and then allowed to cool naturally.

[0014] Furthermore, the specific steps for applying a transparent metal oxide precursor solution using a blade coating method, followed by heat treatment to form a transparent metal oxide top layer, to obtain a three-layer composite conductive film are as follows: A zinc oxide aluminum precursor solution was prepared, wherein the precursor solution was composed of zinc acetate dihydrate, aluminum nitrate nonahydrate, anhydrous ethanol and monoethanolamine, wherein the concentration of zinc acetate dihydrate was 80 mg / mL-140 mg / mL, the concentration of aluminum nitrate nonahydrate was 2.5 mg / mL, and the molar ratio of monoethanolamine to zinc acetate was 1:1. The precursor solution was stirred in a water bath at 50°C to 70°C for 1 to 2 hours to obtain a clear and transparent precursor solution. The precursor liquid was coated onto the surface of the PEDOT:PSS / silver nanowire composite layer that had been fused together using a blade coating method. After coating, the solvent was removed by pre-baking at 120°C for 5 minutes, and then the temperature was raised to 350°C under a nitrogen atmosphere and held for 30 minutes to form a zinc-aluminum oxide top layer, thus obtaining a three-layer composite conductive film.

[0015] Furthermore, the three-layer composite conductive film is patterned to form a circuit pattern, and the transparent metal oxide layer in the pad area is selectively removed to expose the underlying conductive nanowire network, resulting in a substrate with transparent conductive lines. The specific steps are as follows: Positive photoresist is spin-coated onto a three-layer composite conductive film, and exposure and development are performed using a first mask. The traces and pad areas of the first mask are opaque, while the remaining areas are transparent. The zinc oxide aluminum top layer and composite layer in the exposed area are etched away. Positive photoresist is then spin-coated, and exposure and development are performed using a second mask. The second mask is transparent only in the pad area and opaque in the rest of the area. The photoresist in the pad area is removed, and the zinc-aluminum oxide layer on the surface of the pad is removed briefly with a weak etching solution to expose the underlying silver nanowire network.

[0016] On the other hand, a crystal film screen is provided, which is prepared by the above method.

[0017] The beneficial effects of this invention are: By using a spherical template method to pre-prepare a regularly arranged metal nano-array on the substrate surface, the silver nanowires are orderly distributed with the array as the "skeleton" during the subsequent coating process, forming a regular conductive network. This avoids the local sheet resistance differences caused by traditional random overlap and significantly improves the uniformity of large-area conductive films. Low-temperature fusion welding of the conductive polymer / conductive nanowire composite layer enables localized fusion welding between silver nanowires and between silver nanowires and metal nanoarrays, forming an integrated conductive structure. This effectively reduces contact resistance and improves the conductivity of the film. A transparent metal oxide precursor solution is further coated onto the conductive layer after fusion welding and then heat-treated to form a dense metal oxide top layer. This top layer can effectively block oxygen and moisture, prevent the silver nanowires from oxidizing or sulfiding, and at the same time improve the mechanical strength of the film and its adhesion to the substrate, thus extending the service life of the device. By performing two patterning processes on the three-layer composite conductive film, the transparent metal oxide layer in the pad area is selectively removed while the protective layer in the trace area is retained, exposing the underlying conductive nanowire network in the pad area. This allows for low-resistance electrical connection directly to the light-emitting chip without additional etching or surface treatment, simplifying subsequent packaging processes. Attached Figure Description

[0018] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0019] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0020] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Example 1: This embodiment provides a method for preparing a crystal film screen, including the following steps: Step S10: Perform hydroxylation treatment on the surface of the flexible transparent substrate to obtain a hydroxylated substrate; Step S20: Constructing transparent conductive lines on the hydroxylated substrate; the construction of transparent conductive lines includes the following steps: Step S21: Synthesize the silver nanowire dispersion using a one-pot polyol method; Step S22: Prepare a regularly arranged metal nanoarray on the surface of the hydroxylated substrate using a removable spherical template method; Step S23: Mix the silver nanowire dispersion, the conductive polymer aqueous solution, and the surfactant to prepare a composite coating solution; Step S24: The composite coating liquid is coated onto a substrate with a metal nano-array using a blade coating method to form a conductive polymer / conductive nanowire composite layer. Step S24-1: Perform low-temperature fusion welding on the conductive polymer / conductive nanowire composite layer to achieve localized fusion welding between the silver nanowires and between the silver nanowires and the metal nanoarray; Step S25: The transparent metal oxide precursor liquid is then coated by a blade coating method, and a transparent metal oxide top layer is formed by heat treatment to obtain a three-layer composite conductive film. Step S26: The three-layer composite conductive film is patterned to form a circuit pattern, and the transparent metal oxide layer in the pad area is selectively removed to expose the lower conductive nanowire network, thereby obtaining a substrate with transparent conductive lines. Step S30: Electrically connect the light-emitting chip to the substrate with transparent conductive lines using a conductive connection material; Step S40: The obtained substrate is encapsulated to form a protective layer on its surface, thus obtaining a crystal film screen.

[0023] In summary, the crystal film screen obtained by the preparation method of the present invention has the following advantages compared with existing crystal film screens: By using a spherical template method to pre-prepare a regularly arranged metal nano-array on the substrate surface, the silver nanowires are orderly distributed with the array as the "skeleton" during the subsequent coating process, forming a regular conductive network. This avoids the local sheet resistance differences caused by traditional random overlap and significantly improves the uniformity of large-area conductive films. Low-temperature fusion welding of the conductive polymer / conductive nanowire composite layer enables localized fusion welding between silver nanowires and between silver nanowires and metal nanoarrays, forming an integrated conductive structure. This effectively reduces contact resistance and improves the conductivity of the film. A transparent metal oxide precursor solution is further coated onto the conductive layer after fusion welding and then heat-treated to form a dense metal oxide top layer. This top layer can effectively block oxygen and moisture, prevent the silver nanowires from oxidizing or sulfiding, and at the same time improve the mechanical strength of the film and its adhesion to the substrate, thus extending the service life of the device. By performing two patterning processes on the three-layer composite conductive film, the transparent metal oxide layer in the pad area is selectively removed while the protective layer in the trace area is retained, exposing the underlying conductive nanowire network in the pad area. This allows for low-resistance electrical connection directly to the light-emitting chip without additional etching or surface treatment, simplifying subsequent packaging processes.

[0024] In this embodiment, step S10: performing hydroxylation treatment on the surface of the flexible transparent substrate to obtain the hydroxylated substrate, the specific steps are as follows: Colorless polyimide films with a thickness of 50 μm–125 μm were selected as flexible transparent carriers. The films were sequentially placed in acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning for 5 min–20 min each to remove surface oil and particulate matter.

[0025] The cleaned film is immersed in a mixed solution of ammonia and hydrogen peroxide in a volume ratio of 2:1, where the ammonia concentration can be 25 wt% and the hydrogen peroxide concentration can be 30 wt%. The film is heated and stirred at 100 rpm for 1 hour in a constant temperature water bath or oil bath at 70°C to induce a hydroxylation reaction on the film surface and form active hydroxyl groups.

[0026] The treated membrane is removed and rinsed 2–3 times with deionized water, then dried with nitrogen. It is then placed in a UV-ozone cleaner for 5–15 minutes (UV lamp power can be 50W–200W, wavelengths primarily 185nm and 254nm) to further remove residual organic matter and enhance surface wettability. After treatment, the water contact angle on the membrane surface should decrease to below 20°, indicating good hydrophilicity.

[0027] This step involves chemical and physical treatment to form a uniform hydrophilic layer on the CPI surface, ensuring the uniformity and adhesion of subsequent microsphere self-assembly and coating spread.

[0028] In this embodiment, step S21: the specific steps for synthesizing the silver nanowire dispersion using the one-pot polyol method are as follows: The following reactants are added to the reaction vessel at once: Silver nitrate solution: concentration 0.2 mol / L; Polyvinylpyrrolidone (PVP) solution: concentration 0.4 mol / L, wherein PVP is a mixture of 1.3 million molecular weight (Mw=1,300,000) and 24,000 molecular weight (Mw=24,000) in a mass ratio of 2:1; Ethylene glycol: used as a solvent and reducing agent, in an amount of 2–3 times the volume of silver nitrate solution; Sodium chloride solution: concentration 6 mmol / L; Sodium bromide solution: concentration 3 mmol / L; The molar ratio of chloride ions to bromide ions is controlled at 2:1.

[0029] After thoroughly mixing, the mixture is placed in an oil bath and heated, with the reaction temperature controlled at 130°C–150°C. Nitrogen gas is continuously introduced during the reaction (flow rate 0.5 L / min–2 L / min) to remove oxygen. Mechanical stirring is used at 100 rpm–300 rpm, and the reaction time is 1.5 h–2.5 h.

[0030] After the reaction is complete, allow it to cool naturally to room temperature. Dilute with anhydrous ethanol and shake thoroughly to disperse the product. Transfer the mixture to a centrifuge tube and centrifuge. After centrifugation, discard the supernatant. Add ethanol to the precipitate, sonicate for 5–10 minutes, and centrifuge again. Repeat the centrifugation-dispersion process three times.

[0031] Finally, the washed precipitate was redispersed in anhydrous ethanol to obtain a silver nanowire dispersion. The typical size range of the obtained silver nanowires is: diameter 40 nm–55 nm, length 40 μm–60 μm, and aspect ratio 900–1100. The concentration of the dispersion can be adjusted according to subsequent coating requirements, controlled at 2 mg / mL–8 mg / mL.

[0032] This step synthesizes high-purity, high aspect ratio silver nanowires in a one-pot process, ensuring that the subsequent conductive network has high conductivity and low packing density.

[0033] In this embodiment, step S22: the specific steps for preparing a regularly arranged metal nano-array on the surface of the hydroxylated substrate using a removable spherical template method are as follows: Polystyrene (PS) microspheres with an average diameter of 1.0 μm were prepared into an aqueous dispersion with a solid content of 0.5 wt% using deionized water. The hydrophilic film prepared in step S10 was placed flat on a horizontal platform. 20 μL–100 μL of the PS microsphere dispersion was pipetted onto the film surface. The film was gently tilted to allow the dispersion to spread evenly. It was then placed at room temperature for 10–60 minutes to allow the water to evaporate slowly. Under the action of capillary force and surface tension, the microspheres self-assembled to form a monolayer of closely packed hexagonal templates.

[0034] The thin film with the PS microsphere template was placed on the sample stage of the vacuum sputtering coating machine. A vacuum of 5 × 10⁻⁶ was applied. - ³Pa–1×10 -High-purity argon gas was introduced as the working gas, and the working gas pressure was adjusted to 0.5 Pa–2 Pa. The sputtering current was set to 5 mA–20 mA, and the sputtering time was 30 s–120 s to deposit a 20 nm–30 nm silver film between the microspheres in the microsphere template. During sputtering, the substrate could be kept at room temperature or appropriately cooled (<50°C) to prevent deformation of the PS microspheres.

[0035] The samples with deposited silver films were sequentially immersed in the following solutions: Dichloromethane: Dissolve PS microspheres by ultrasonic oscillation at room temperature for 2-10 minutes (power 50W-200W, frequency 40kHz); Acetone: Ultrasonic oscillation at room temperature for 2-10 minutes to further remove residual PS and organic impurities; Anhydrous ethanol or deionized water: Rinse for 1-2 minutes to remove residual solvent.

[0036] The sample surface was then dried by blowing with a stream of nitrogen.

[0037] After removing the PS microspheres, a silver dot matrix consisting of triangular silver particles arranged in a hexagonal pattern is formed on the film surface. The base length of each triangular silver particle is approximately 0.5 μm–1.2 μm, the particle height is 10 nm–25 nm, and the center-to-center spacing between adjacent silver particles is 0.8 μm–1.5 μm.

[0038] This step utilizes a PS microsphere self-assembly template and sputtering process to form a regular hexagonal silver dot matrix on the substrate, serving as the "skeleton" for the subsequent silver wire network, guiding the orderly distribution of silver wires, reducing the amount of silver wire used, and improving conductivity uniformity.

[0039] In this embodiment, step S23, which involves mixing the silver nanowire dispersion, the conductive polymer aqueous solution, and the surfactant to prepare the composite coating solution, is as follows: The silver nanowire dispersion obtained in step S21 is mixed with an aqueous solution of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) at a volume ratio of 1:3. A fluorocarbon surfactant is added at a volume of 0.2% of the total volume of the mixture. If the viscosity is too high, it can be adjusted to a suitable viscosity for coating (50 cP–200 cP) using ethylene glycol or dimethyl sulfoxide. The components are thoroughly mixed using a magnetic stirrer or shaker to obtain the composite coating solution.

[0040] This step disperses the silver wires in the PEDOT:PSS matrix, reducing surface tension and forming a stable, uniform doctor blade ink.

[0041] In this embodiment, step S24: applying the composite coating liquid onto a substrate with a metal nano-array using a blade coating method to form a conductive polymer / conductive nanowire composite layer is shown in the following steps: The film with silver dot matrix obtained in step S22 is smoothly fixed on the heating stage of the automatic coating machine. The heating stage temperature is set to 55°C. The gap between the doctor blade and the film surface is adjusted to an appropriate value (e.g., 80μm–120μm). 0.3mL–0.8mL of the composite coating solution is pipetted and evenly injected onto the film in front of the doctor blade. The coating machine is started, and the doctor blade moves at a constant speed to spread the coating solution into a wet film.

[0042] Immediately transfer the coated film to a heating platform and heat-treat at 120°C for 8 minutes to allow the solvent to evaporate and the film to cure. After cooling to room temperature, immerse the film in anhydrous methanol and lift it up and down to remove the highly insulating PSS component from the film layer. Remove the film and dry it in an oven at 60°C–80°C for 10–20 minutes.

[0043] Repeat the above "coating-heat treatment-methanol pulling-drying" process 1-3 times to obtain a thin film with a PEDOT:PSS / silver nanowire composite layer as the bottom layer. The total thickness of the composite layer can be controlled by the number of coating cycles.

[0044] This step achieves large-area, high-efficiency film formation through a scraping method, removes insulating PSS by methanol lifting, and reduces sheet resistance through multi-layer stacking.

[0045] In this embodiment, step S24-1: the specific steps of performing low-temperature fusion welding on the conductive polymer / conductive nanowire composite layer are as follows: The dried PEDOT:PSS / silver nanowire composite layer was placed in a vacuum drying oven and evacuated to -0.08MPa to -0.1MPa. It was then heated to 180°C–200°C and held for 20–40 minutes. At this temperature, localized melting and welding occurred at the contact points between the silver nanowires and between the silver nanowires and the underlying silver mesh lattice, forming an integrated conductive network and significantly reducing contact resistance. After heat treatment, the layer was allowed to cool naturally to room temperature.

[0046] This step involves thermally welding the silver wires together and between the silver wires and the dot matrix while the silver wires are exposed, eliminating contact resistance and significantly reducing sheet resistance.

[0047] In this embodiment, step S25: the transparent metal oxide precursor liquid is then coated using a blade coating method, and a transparent metal oxide top layer is formed by heat treatment to obtain a three-layer composite conductive film. The specific steps are as follows: Preparation of zinc oxide aluminum precursor solution: Dissolve 80 mg / mL zinc acetate dihydrate and 2.5 mg / mL aluminum nitrate nonahydrate in anhydrous ethanol, add monoethanolamine, and control the molar ratio of monoethanolamine to zinc acetate to be 1:1. Stir in a water bath at 50°C–70°C for 1–2 hours to obtain a clear and transparent precursor solution.

[0048] Using the same coating parameters as in step S24, the AZO precursor solution was coated onto the surface of the already fused PEDOT:PSS / silver nanowire composite layer. After coating, the film was pre-baked on a 120°C heating platform for 5 minutes to remove the solvent. Then, the film was transferred to a tube furnace and heated to 350°C under a nitrogen atmosphere, held for 30 minutes, to allow the zinc acetate to completely decompose and crystallize into a dense zinc-aluminum oxide top layer. The thickness of the top layer can be controlled by multiple coatings, with a single coating thickness of approximately 20–30 nm. This yields a three-layer composite conductive film.

[0049] This step coats the fused silver wire network with a high-hardness, dense AZO layer, protecting the silver wire from oxidation and scratches, while providing a hard mask for subsequent photolithography.

[0050] In this embodiment, step S26: patterning the three-layer composite conductive film to form a circuit pattern, and selectively removing the transparent metal oxide layer in the pad area to expose the underlying conductive nanowire network, resulting in a substrate with transparent conductive lines, are as follows: Positive photoresist is spin-coated onto the entire composite conductive film (the top layer being zinc oxide). The spin-coated film is placed on a hot plate and heated to remove the organic solvents from the photoresist, allowing it to cure. Using a UV lithography machine, exposure is performed through a first mask (the areas of the traces and pads on the mask are opaque, while the rest are transparent). The exposed film is then immersed in a positive developer solution. After development, the pattern is checked for clarity and neatness of the edges. The developed film is heated on a hot plate to enhance the photoresist's etch resistance. The film with the photoresist pattern is then immersed in an etching solution, which removes the zinc oxide top layer and the PEDOT:PSS / silver nanowire composite layer in the exposed areas until the underlying substrate is exposed. After etching, residual etching solution is removed with deionized water. The etched film is then immersed in a photoresist stripping solution to remove the photoresist. At this point, a trace and pad pattern covered with a zinc oxide protective layer is obtained (the conductive layer in non-circuit areas has been completely removed).

[0051] Positive photoresist is spin-coated again onto the patterned substrate. After pre-baking, a second mask (with only the pad areas transparent and the rest opaque) is used for exposure and development to remove the photoresist from the pad areas, while retaining it on the traces and other areas. Then, a short-term etching solution (e.g., 0.3 mol / L–0.5 mol / L dilute hydrochloric acid, etched at room temperature for 10–30 seconds) is used to remove the zinc oxide layer on the pad surface, exposing the underlying silver nanowire network. The reaction is immediately terminated by rinsing with deionized water. Finally, the remaining photoresist is removed. This yields a patterned transparent conductive circuit substrate with exposed silver lines in the pad areas and the trace areas still covered by zinc oxide.

[0052] This step involves two photolithography and etching processes to precisely form the circuit traces, while preserving AZO protection in the trace area and exposing only the silver lines in the pad area, providing a metal contact surface for subsequent chip connections.

[0053] In this embodiment, step S30: electrically connecting the light-emitting chip to the substrate with transparent conductive lines via a conductive connection material is as follows: Micron-sized red, green, and blue LED chips are transferred to their corresponding pad positions using a mass transfer device. Anisotropic conductive adhesive is then used to heat-press the chips for 10–30 seconds at 150°C–180°C and 1MPa–3MPa pressure, allowing the conductive particles to directly contact the exposed silver nanowires and achieve electrical connection.

[0054] This step utilizes the thermo-pressing properties of ACA to reliably connect the LED chip electrodes to the silver wires in the pad area, while also providing mechanical fixation.

[0055] In this embodiment, step S40: encapsulating the obtained substrate and forming a protective layer on its surface to obtain the crystal screen. The specific steps are as follows: A transparent optical-grade UV-curable adhesive is coated onto the surface of the assembled chip film. Coating methods include blade coating, spray coating, or spin coating. The film coated with the UV-curable adhesive is placed in a vacuum chamber to remove air bubbles from the adhesive layer. After degassing, a UV lamp is used to fully cure the adhesive, forming an outer protective film. After encapsulation, the crystal screen is obtained.

[0056] This step uses UV adhesive to form a highly transparent and strong outer encapsulation, improving the device's environmental stability and mechanical strength.

[0057] Example 2: The second embodiment of the present invention also provides a method for preparing a crystal film screen. The method for preparing the crystal film screen in the second embodiment of the present invention differs from that in the first embodiment in that: In step S10: the volume ratio of ammonia to hydrogen peroxide is 4:1, the heating temperature is 90°C, the stirring speed is 300 rpm, and the time is 2 hours.

[0058] In step S21: the concentration of silver nitrate solution is 0.4 mol / L, the concentration of PVP solution is 0.6 mol / L, the concentration of sodium chloride is 10 mmol / L, and the concentration of sodium bromide is 5 mmol / L (chlorine-bromine molar ratio 2:1).

[0059] In step S22: the average diameter of the PS microspheres is 2.5 μm, and the solid content of the dispersion liquid is 5 wt%. In the silver lattice formed after removing the PS microspheres, the base length of each triangular silver particle is approximately 1.2 μm–2.0 μm, the particle height is 15 nm–30 nm, and the center-to-center distance between adjacent silver particles is 2.0 μm–3.0 μm.

[0060] In step S24: the heating table temperature is 75°C, the heat treatment temperature is 140°C, and the time is 15 minutes.

[0061] In step S25: the concentration of zinc acetate dihydrate is 140 mg / mL.

[0062] The remaining parameters in this embodiment are the same as those in Embodiment 1.

[0063] The final devices fabricated using the methods described in Examples 1 and 2, compared to traditional crystal film screens, exhibit the following performance indicators:

[0064] Among them, the difficulty in direct connection or the need for additional processes in the existing technology can be understood as the silver nanowire transparent conductive film in the existing technology. Its pad area surface is usually covered with an insulating PSS or oxide layer, or the silver wire has been oxidized, which makes it impossible to achieve low-resistance connection directly with the light-emitting chip. It often requires additional laser etching, plasma treatment or chemical etching steps, which are complex and have low reliability.

[0065] In summary, the crystal film screen prepared by the method of the present invention has better photoelectric performance, mechanical reliability and environmental stability compared with the prior art in Example 1 and Example 2.

[0066] Example 3: This embodiment provides a crystal film screen, which is prepared by the method in Embodiment 1 or Embodiment 2.

[0067] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0068] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a crystal film screen, characterized in that, Includes the following steps: A hydroxylated substrate is obtained by hydroxylating the surface of a flexible transparent substrate. Constructing transparent conductive lines on the hydroxylated substrate; the construction of transparent conductive lines includes the following steps: A one-pot polyol method was used to synthesize a dispersion of silver nanowires. A regularly arranged metal nanoarray was prepared on the surface of the hydroxylated substrate using a removable spherical template method. The nano-silver wire dispersion, the conductive polymer aqueous solution, and the surfactant are mixed to prepare a composite coating solution. The composite coating liquid is applied onto a substrate with a metal nano-array using a blade coating method to form a conductive polymer / conductive nanowire composite layer. The conductive polymer / conductive nanowire composite layer is subjected to low-temperature fusion welding to cause localized fusion welding between the silver nanowires and between the silver nanowires and the metal nanoarray. Then, a transparent metal oxide precursor liquid is coated by a blade coating method, and a transparent metal oxide top layer is formed by heat treatment to obtain a three-layer composite conductive film. The three-layer composite conductive film is patterned to form a circuit pattern, and the transparent metal oxide layer in the pad area is selectively removed to expose the underlying conductive nanowire network, resulting in a substrate with transparent conductive lines. The light-emitting chip is electrically connected to the substrate with transparent conductive lines via a conductive connecting material. The obtained substrate is encapsulated to form a protective layer on its surface, thus obtaining a crystal film screen; The specific steps for performing low-temperature fusion welding on the conductive polymer / conductive nanowire composite layer are as follows: The dried composite layer is placed in a vacuum drying oven, evacuated to -0.08MPa to -0.1MPa, heated to 180°C to 200°C, held for 20 to 40 minutes, and then allowed to cool naturally.

2. The method for preparing a crystal film screen according to claim 1, characterized in that, The specific steps for hydroxylation treatment of the flexible transparent substrate surface include: The flexible transparent substrate was ultrasonically cleaned in acetone, anhydrous ethanol and deionized water in sequence. The cleaned substrate is immersed in a mixed solution of ammonia and hydrogen peroxide at a volume ratio of (1-4):1, and heated and stirred at 70°C-90°C for 1-2 hours. Then it is rinsed with deionized water, dried with nitrogen, and then irradiated in an ultraviolet-ozone cleaner for 5-15 minutes to obtain a hydroxylated substrate.

3. The method for preparing a crystal film screen according to claim 2, characterized in that, The specific steps for synthesizing the silver nanowire dispersion using the one-pot polyol method include: Add the following solutions to the reaction vessel at once: silver nitrate solution, polyvinylpyrrolidone solution, ethylene glycol, sodium chloride solution, and sodium bromide solution to obtain a mixture; After the mixture is stirred evenly, it is heated to react, and the reaction temperature is controlled at 130°C–150°C. Nitrogen gas was continuously introduced during the reaction to remove oxygen, and the mixture was stirred. The reaction time was 1.5 h to 2.5 h. After the reaction is complete, allow it to cool naturally to room temperature, add anhydrous ethanol to dilute, shake thoroughly to disperse the product, then centrifuge, discard the supernatant, add ethanol to the precipitate, sonicate for 5-10 minutes, centrifuge again, and repeat the centrifugation-dispersion operation 3 times. Finally, the washed precipitate was redispersed in anhydrous ethanol to obtain a dispersion of silver nanowires.

4. The method for preparing a crystal film screen according to claim 3, characterized in that, The specific steps for preparing a regularly arranged metal nanoarray on the surface of the hydroxylated substrate using a removable spherical template method include: Polystyrene microspheres with an average diameter of 1.0 μm to 2.5 μm were used to prepare an aqueous dispersion with a solid content of 0.5 wt% to 5 wt% using deionized water; The aqueous dispersion is dropped onto the surface of the hydroxylated substrate and left to stand for 10 min to 60 min, so that the microspheres self-assemble to form a single layer of closely packed hexagonal template. A substrate with a polystyrene microsphere template was placed in a vacuum sputtering coating machine, and a vacuum of 5 × 10⁻⁶ was applied. -3 Pa ~ 1×10 - 2 Pa, introduce high-purity argon gas, adjust the working gas pressure to 0.5Pa~2Pa, set the sputtering current to 5mA~20mA, and the sputtering time to 30s~120s, deposit a 20nm~30nm silver film in the gap between the microspheres, and keep the substrate temperature below 50°C during the sputtering process; The sample with deposited silver film was sequentially immersed in dichloromethane and ultrasonically vibrated for 2 min to 10 min, then immersed in acetone and ultrasonically vibrated for 2 min to 10 min, then rinsed with anhydrous ethanol or deionized water for 1 min to 2 min, and finally dried with nitrogen to remove polystyrene microspheres, forming a silver dot matrix on the substrate surface consisting of triangular silver particles arranged in a hexagonal pattern, thus obtaining a silver dot matrix film.

5. The method for preparing a crystal film screen according to claim 4, characterized in that, The specific steps for mixing the silver nanowire dispersion, the conductive polymer aqueous solution, and the surfactant to prepare the composite coating solution are as follows: The nano-silver wire dispersion was mixed with PEDOT:PSS aqueous solution at a volume ratio of 1:3, a fluorocarbon surfactant was added, and the viscosity was adjusted to 50 cP-200 cP with ethylene glycol or dimethyl sulfoxide. The mixture was then thoroughly mixed.

6. The method for preparing a crystal film screen according to claim 5, characterized in that, The specific steps for applying the composite coating liquid onto a substrate with a metal nanoarray using a blade coating method to form a conductive polymer / conductive nanowire composite layer are as follows: The silver dot matrix film is flattened and fixed on the heating table of the automatic coating machine, and the temperature of the heating table is set to 55°C-75°C; the gap between the doctor blade and the film surface is adjusted to 80μm-120μm; 0.3mL-0.8mL of composite coating liquid is taken and evenly injected onto the film in front of the doctor blade; the coating machine is started, and the doctor blade moves at a constant speed to spread the coating liquid into a wet film; The coated film is transferred to a heating platform for heat treatment to allow the solvent to evaporate and the film to cure. After cooling to room temperature, the film is immersed in anhydrous methanol and pulled up and down to remove the PSS component; the film is then removed and dried. Repeat the above "coating-heat treatment-methanol pulling-drying" process at least once to obtain a thin film with a PEDOT:PSS / silver nanowire composite layer as the bottom layer.

7. The method for preparing a crystal film screen according to claim 6, characterized in that, The specific steps for applying a transparent metal oxide precursor solution using a blade coating method, followed by heat treatment to form a transparent metal oxide top layer, and obtaining a three-layer composite conductive film are as follows: A zinc oxide aluminum precursor solution was prepared, wherein the precursor solution was composed of zinc acetate dihydrate, aluminum nitrate nonahydrate, anhydrous ethanol and monoethanolamine, wherein the concentration of zinc acetate dihydrate was 80 mg / mL-140 mg / mL, the concentration of aluminum nitrate nonahydrate was 2.5 mg / mL, and the molar ratio of monoethanolamine to zinc acetate was 1:

1. The precursor solution was stirred in a water bath at 50°C to 70°C for 1 to 2 hours to obtain a clear and transparent precursor solution. The precursor liquid was coated onto the surface of the PEDOT:PSS / silver nanowire composite layer that had been fused together using a blade coating method. After coating, the solvent was removed by pre-baking at 120°C for 5 minutes, and then the temperature was raised to 350°C under a nitrogen atmosphere and held for 30 minutes to form a zinc-aluminum oxide top layer, thus obtaining a three-layer composite conductive film.

8. The method for preparing a crystal film screen according to claim 7, characterized in that, The specific steps for patterning the three-layer composite conductive film to form a circuit pattern and selectively removing the transparent metal oxide layer in the pad area to expose the underlying conductive nanowire network to obtain a substrate with transparent conductive lines are as follows: Positive photoresist is spin-coated onto a three-layer composite conductive film, and exposure and development are performed using a first mask. The traces and pad areas of the first mask are opaque, while the remaining areas are transparent. The zinc oxide aluminum top layer and composite layer in the exposed area are etched away. Positive photoresist is then spin-coated, and exposure and development are performed using a second mask. The second mask is transparent only in the pad area and opaque in the rest of the area. The photoresist in the pad area is removed, and the zinc-aluminum oxide layer on the surface of the pad is removed briefly with a weak etching solution to expose the underlying silver nanowire network.

9. A crystal film screen, characterized in that, The crystal film screen is prepared by the method of any one of claims 1-8.

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