Silver nanowire-arabic gum composite transparent degradable conductive film and preparation method and application thereof

Abstract

This invention discloses a silver nanowire-gum arabic composite transparent biodegradable conductive film, its preparation method, and its applications. The process begins with the preparation of a silver nanowire suspension and a gum arabic solution. A substrate is then subjected to a hydrophilic treatment to obtain a pretreated substrate. The silver nanowire suspension is first coated onto the pretreated substrate, followed by heating and curing to form a silver nanowire film. Subsequently, a gum arabic solution is coated onto the silver nanowire film, and heating and curing further results in the silver nanowire-gum arabic composite transparent biodegradable conductive film. By introducing gum arabic, this invention achieves ultra-high transparency and excellent conductivity while simultaneously endowing the film with a smooth surface morphology, excellent mechanical stability, oxidation resistance, high-temperature resistance, and environmentally friendly properties. This provides a new technological path for low-cost, environmentally friendly, and large-scale production of flexible optoelectronic devices, demonstrating significant application potential and market value in the field of flexible optoelectronics.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic device technology, specifically relating to a silver nanowire-gum arabic composite transparent biodegradable conductive film, its preparation method, and its application. Background Technology

[0002] Flexible transparent electrodes are core components of flexible electronic devices. With their superior optoelectronic properties, mechanical durability, and environmental adaptability, these electrodes are widely used in flexible touchscreens, displays, energy storage devices, and smart windows. For decades, indium tin oxide (ITO) has dominated the transparent electrode market due to its excellent light transmittance and low resistivity. However, its inherent brittleness, the scarcity of indium resources, and high manufacturing costs have severely limited its application in flexible electronics. To address these limitations, researchers have explored alternative materials, including conductive polymers, graphene, carbon nanotubes, and metal-based nanostructures.

[0003] Among these materials, silver nanowires (AgNWs) have attracted widespread attention due to their excellent optoelectronic properties, mechanical flexibility, and solution processability. However, their high surface roughness and insufficient stability have long hindered their widespread application in industry. To overcome these intrinsic defects, researchers have employed post-processing methods such as mechanical hot pressing and photowelding, contact transfer schemes, and coating technologies. Among these, coating technology has the advantage of one-step preparation and has been widely used to modify AgNWs electrodes. Although researchers have developed various silver nanowire composite electrodes using metal oxides, graphene, or conductive polymers, few electrodes can simultaneously achieve low surface roughness, high stability, and excellent optoelectronic properties. Moreover, most coating technologies are often cumbersome and costly, making them difficult to apply in practice. Furthermore, the materials currently used to modify silver nanowires generally lack sustainability and environmental friendliness, further limiting their long-term application prospects. Therefore, it is essential to develop a method to directly form silver nanowire films with low surface roughness, high adhesion, mechanical stability, thermal stability, and environmental stability on flexible polymer substrates without sacrificing their optoelectronic properties. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a silver nanowire-gum arabic composite transparent biodegradable conductive film, its preparation method, and its application. Utilizing gum arabic material and through an environmentally friendly preparation process, a flexible transparent electrode with excellent mechanical stability, thermal stability, environmental stability, surface smoothness, and ultra-high transparency is achieved.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a transparent and biodegradable conductive film composed of silver nanowires and gum arabic includes the following steps: Step 1, Preparation of silver nanowire solution Using a silver nanowire dispersion as a precursor solution, it is mixed with solvent A to obtain a silver nanowire (AgNWs) solution. The concentration of AgNWs in the AgNWs solution is 1-5 mg / mL. Solvent A is anhydrous ethanol, isopropanol, or deionized water. Step 2, Preparation of gum arabic solution Gum arabic was mixed with solvent B and then ultrasonically dissolved until homogeneous. The concentration of the resulting gum arabic solution was 20–100 mg / mL. Solvent B was a mixture of deionized water and anhydrous ethanol in a volume ratio of 7:3. Step 3, Transparent substrate pretreatment The substrate was cleaned and treated with a UV / ozone cleaner for 5 minutes to enhance its surface hydrophilicity, resulting in a pretreated substrate. Step 4, Preparation of silver nanowire-gum arabic composite film First, an AgNWs solution is coated onto a pretreated substrate and cured at 90–120°C for 10–20 min to form an AgNWs film. Then, an arabic resin solution is coated onto the AgNWs film and cured at 80–100°C for 10–20 min to form a silver nanowire-arabic resin composite transparent biodegradable conductive film.

[0006] As an improvement, in step 3, the material of the substrate is glass, cellulose, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polyimide (PI).

[0007] As an improvement, the specific steps for cleaning the substrate in step 3 are as follows: the substrate is ultrasonically cleaned for 15-20 minutes in sequence with detergent, deionized water, acetone and isopropanol.

[0008] As an improvement, the coating method described in step 4 is blade coating, Mayer bar coating, slot coating, spraying, or spin coating.

[0009] The silver nanowire-gum arabic composite transparent biodegradable conductive film was prepared based on any of the above preparation methods.

[0010] The above-mentioned silver nanowire-gum arabic composite transparent biodegradable conductive film can be used in flexible transparent electrodes, implantable devices, organic light-emitting diodes, organic photovoltaics, or environmentally friendly packaged electronic products.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention uses a solution method to coat gum arabic material onto the surface of a silver nanowire film as a protective layer, and develops a method to directly form a silver nanowire film with ultra-high transparency, excellent electrical conductivity, low surface roughness, high viscosity, mechanical stability and thermal stability on a flexible polymer substrate, which greatly improves the performance of the silver nanowire film in multiple aspects. 2) The gum arabic material used in this invention is an environmentally friendly and pollution-free material that is readily available and inexpensive. It has value in new application scenarios such as flexible electronic waste treatment and biocompatible devices. The modified silver nanowire electrode preparation process is simple, helps reduce pollution in industrial production, has good coating uniformity, and is suitable for industrial production. Attached Figure Description

[0012] Figure 1 Photographs of different electrodes, where (a) is an AgNWs / PET electrode and (b) is an AgNWs / gum arabic / PET electrode; Figure 2 The sheet resistance of AgNWs and AgNWs / gum arabic composite films; Figure 3 The transmittance of AgNWs and AgNWs / gum arabic composite films; Figure 4 The intrinsic transmittance of gum arabic on PET and glass and atomic force microscopy (AFM) images of PET / gum arabic are shown, where (a) is the intrinsic transmittance of gum arabic on PET, (b) is the intrinsic transmittance of gum arabic on glass, (c) is an AFM image of PET, and (d) is an AFM image of PET / gum arabic.

[0013] Figure 5 Atomic force microscopy (AFM) images of AgNWs and AgNWs / gum arabic composite films and their corresponding 3D images are shown, where (a) is an AFM image of AgNWs, (b) is an AFM image of AgNWs / gum arabic composite films, (c) is a 3D image of AgNWs, and (d) is a 3D image of AgNWs / gum arabic composite films. Figure 6 A comparison of the changes in relative sheet resistance of AgNWs thin films and AgNWs / gum arabic composite films after 200,000 bending cycles with a bending radius of 1 mm. Figure 7The curves showing the change in relative sheet resistance of AgNWs and AgNWs / gum arabic composite films during 200 tape peeling cycles; Figure 8 The sheet resistance changes of the original AgNWs electrode and the composite electrode after heat treatment at different temperatures for 600 s; Figure 9 The change in sheet resistance of AgNWs / gum arabic composite film after 150 days of storage in air; Figure 10 The images are atomic force microscopy (AFM) images of AgNWs / gum arabic composite films after being stored at ~80°C and ~80% relative humidity for 120 days. (a) is the atomic force microscopy (AFM) image of the AgNWs / gum arabic composite film after being stored at ~80°C and ~80% relative humidity for 120 days, and (b) is the corresponding 3D image.

[0014] Figure 11 Images of the AgNWs / gum arabic composite film undergoing natural degradation in a 1wt% acetic acid solution over three hours; Figure 12 The images show a schematic diagram, efficiency-brightness curve, and physical image of a flexible green phosphorescent OLED device fabricated using AgNWs / gum arabic composite film. (a) is a schematic diagram of the flexible green phosphorescent OLED device, (b) is the efficiency-brightness curve, and (c) is a physical image of a large-area OLED device emitting light in a bent state. Detailed Implementation

[0015] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto: A method for preparing a transparent and biodegradable conductive film composed of silver nanowires and gum arabic includes the following steps: Step 1, Preparation of silver nanowire solution Using a silver nanowire dispersion as a precursor solution, it is mixed with solvent A to obtain a silver nanowire (AgNWs) solution. The concentration of AgNWs in the AgNWs solution is 1-5 mg / mL. Solvent A is anhydrous ethanol, isopropanol, or deionized water. Step 2, Preparation of gum arabic solution Gum arabic was mixed with solvent B and then ultrasonically dissolved until homogeneous. The concentration of the resulting gum arabic solution was 20–100 mg / mL. Solvent B was a mixture of deionized water and anhydrous ethanol in a volume ratio of 7:3. Step 3, Transparent substrate pretreatment The substrate was cleaned and treated with a UV / ozone cleaner for 5 minutes to enhance its surface hydrophilicity, resulting in a pretreated substrate. Step 4, Preparation of silver nanowire-gum arabic composite film First, an AgNWs solution is coated onto a pretreated substrate and cured at 90–120°C for 10–20 min to form an AgNWs film. Then, an arabic resin solution is coated onto the AgNWs film and cured at 80–100°C for 10–20 min to form a silver nanowire-arabic resin composite transparent biodegradable conductive film.

[0016] As an improvement, in step 3, the material of the substrate is glass, cellulose, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polyimide (PI).

[0017] As an improvement, the specific steps for cleaning the substrate in step 3 are as follows: the substrate is ultrasonically cleaned for 15-20 minutes in sequence with detergent, deionized water, acetone and isopropanol.

[0018] As an improvement, the coating method described in step 4 is blade coating, Mayer bar coating, slot coating, spraying, or spin coating. Example 1

[0019] A method for preparing a transparent and biodegradable conductive film composed of silver nanowires and gum arabic includes the following steps: 1) Preparation of silver nanowire solution and gum arabic solution: Using AgNWs solution as a precursor solution, isopropanol was added to dilute the silver nanowire dispersion to finally obtain silver nanowire ink (AgNWs solution); wherein, the concentration of AgNWs was 2.5 mg / mL; The gum arabic was thoroughly dissolved by ultrasonication after being mixed with solvent B, and the concentration of the gum arabic solution was 80 mg / mL. Solvent B was obtained by mixing anhydrous ethanol and deionized water at a volume ratio of 7:3.

[0020] 2) Pretreatment of PET transparent film substrate: The PET film (125 μm thick) was ultrasonically cleaned for 30 min each with detergent, deionized water, acetone and isopropanol, and then surface-treated for 5 min with a UV / ozone cleaner at 45 W to obtain the pretreated substrate. 3) Preparation of AgNWs / Gum Arabic Composite Transparent Conductive Film: A layer of silver nanowire solution was spin-coated onto the pretreated substrate at 2000 rpm for 30 s using a spin coater, and then cured at 90 °C for 10 min to form an AgNWs thin film. Then, spin-coat a layer of gum arabic onto the AgNWs film at 2000 rpm for 30 seconds, and cure at 90°C for 10 minutes to obtain the AgNWs / gum arabic composite film. Example 2

[0021] The performance and application of the AgNWs / gum arabic composite conductive film prepared in Example 1 are used as an example.

[0022] Figure 1 (b) is a photograph of the AgNWs / gum arabic conductive film, compared with the original AgNWs conductive film. Figure 1 Compared to (a), the AgNWs / gum arabic conductive film also exhibits high transmittance and uniformity. The sheet resistance and transmittance of the conductive film were tested, and the results are as follows: Figure 2 , 3 As shown, the coating of gum arabic has almost no effect on the photoelectric properties of AgNWs conductive films. The composite conductive film has a sheet resistance of less than 20 Ω / sq with a transmittance of more than 95% in the visible light range.

[0023] Test the transmittance of gum arabic on different substrates, specifically as follows: Figure 4 As shown in (a) and (b), gum arabic exhibits approximately 3.4% higher transmittance on a PET substrate than pure PET, and approximately 0.4% lower transmittance on glass than pure glass. This phenomenon is attributed to the excellent film-forming properties of gum arabic, which can quickly smooth rough surfaces such as PET, thereby reducing light scattering and achieving ultra-high transmittance. Even on smooth surfaces such as glass, its transmittance loss is very small, demonstrating the superior optical properties of gum arabic. Figure 4 (c) and (d) show atomic force microscopy (AFM) images of the two surfaces. The arithmetic mean roughness Ra of the unmodified PET surface is 1.9 nm, while the arithmetic mean roughness of the PET surface modified with gum arabic is only 0.38 nm.

[0024] Figure 5 An atomic force microscope (AFM) image of a conductive thin film, showing the original silver nanowire film. Figure 5 (a) has a very high surface roughness (Ra=18 nm), which easily causes short circuits in organic optoelectronic thin film devices, and therefore is not suitable for organic optoelectronic thin film devices. Meanwhile, AgNWs / gum arabic composite conductive films ( Figure 5 (b) has a flat surface with an arithmetic mean roughness Ra of 4.9 nm, making it suitable for organic optoelectronic thin film devices. Figure 5The three-dimensional surface morphology images in (c) and (d) can more intuitively show the surface morphology of the conductive film. Gum arabic can quickly and effectively fill the gaps in the nano-network and reduce roughness.

[0025] The mechanical stability of conductive films was tested by measuring the change in relative sheet resistance (test sheet resistance / original sheet resistance) of AgNWs films and AgNWs / gum arabic composite films after different numbers of bending cycles with a bending radius of 1 mm. Specifically... Figure 6 As shown, after 5000 bends, the sheet resistance of AgNWs film begins to increase significantly, and continues to increase with the number of bends. In contrast, the sheet resistance of AgNWs / gum arabic composite film only changes slightly after 200,000 bends, demonstrating excellent mechanical stability.

[0026] The adhesion of four conductive films to the substrate was tested using 3M Scotch tape, such as... Figure 7 As shown, the original AgNWs electrode lost its conductivity after two tape tests. However, the AgNWs / gum arabic composite film maintained almost constant relative sheet resistance during 200 repeated tape application and peeling cycles.

[0027] To determine the thermal stability of a conductive thin film, the film is placed on a hot stage and heated at different temperatures for 600 seconds (from 80°C to 300°C), and the change in sheet resistance is measured. Specifically... Figure 8 As shown, the sheet resistance of the original AgNWs increases sharply after heating to 180°C and completely fails at 220°C. Due to the size effect at the nanoscale, the original AgNWs exhibit poor thermal stability; compared to macroscopic bulk silver, these nanomaterials are more prone to melting at relatively low temperatures. In contrast, the AgNWs / gum arabic composite film exhibits better thermal stability, with only a slight change in sheet resistance when the temperature rises to 300°C.

[0028] Figure 9 To assess the oxidation resistance of AgNWs / gum arabic composite films, the conductive films were stored in air for 150 days, and the change in sheet resistance was tested. The sheet resistance of the original AgNWs showed large-area oxidation after 10 days, and the conductivity began to decline sharply, eventually failing completely after 120 days. In contrast, the sheet resistance of the AgNWs / gum arabic composite film remained almost unchanged even after 150 days, which is attributed to the strong oxidation resistance of gum arabic.

[0029] Figure 10 (a) An atomic force microscope (AFM) image of the AgNWs / gum arabic composite film stored at ~80°C and ~80% relative humidity for 120 days. Figure 10(b) is the corresponding three-dimensional surface morphology diagram. It can be observed that the surface roughness of the AgNWs / gum arabic composite film increased from 4.9 nm to 12.3 nm under long-term harsh conditions, while the internal AgNWs remained intact, indicating that only the gum arabic covering the AgNWs degraded, demonstrating the strong environmental protection capability of the AgNWs / gum arabic composite film.

[0030] Figure 11 The images show the natural degradation of the AgNWs / gum arabic composite film in a 1 wt% acetic acid solution over three months. The conductive film completely degrades into water and carbon dioxide after 90 days, demonstrating the environmental friendliness of the AgNWs / gum arabic composite film.

[0031] Flexible green phosphorescent OLED devices were fabricated using AgNWs / gum arabic composite films (PET substrates), including flexible OLED devices based on AgNWs / gum arabic composite films such as... Figure 12 As shown in (a), the preparation method is a conventional technique in this field. From Figure 12 As can be seen in (b), the device based on AgNWs / gum arabic flexible composite electrode can achieve 55140 cd / m. -2 Brightness, 77.4 cd A -1 Maximum current efficiency and less than 15% efficiency roll-off.

[0032] In summary, this invention provides a transparent and biodegradable conductive film made of silver nanowires and gum arabic, along with its preparation method and applications. By using a solution method to coat gum arabic onto the surface of the silver nanowire film as a protective layer, the invention significantly improves the mechanical stability, thermal stability, environmental stability, and surface smoothness of the silver nanowire film while maintaining ultra-high transparency and excellent stability. This results in substantial improvements in multiple performance aspects of the silver nanowire film, aligning with the theme of green environmental protection and demonstrating promising development prospects in various fields, making it suitable for industrial production.

[0033] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited thereto. Any simple changes or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing a transparent, biodegradable conductive thin film composed of silver nanowires and gum arabic, characterized in that, Includes the following steps: Step 1: Preparation of silver nanowire solution: A silver nanowire dispersion was used as a precursor solution and mixed with solvent A to obtain a silver nanowire solution. The concentration of silver nanowires in the silver nanowire solution was 1-5 mg / mL. Solvent A was anhydrous ethanol, isopropanol or deionized water. Step 2, Preparation of gum arabic solution: Gum arabic powder is mixed with solvent B and shaken in an ultrasonic cleaner for 20 to 30 minutes to fully dissolve the gum arabic powder, thereby obtaining a gum arabic solution with a concentration of 20 to 100 mg / mL. Solvent B is a mixture of deionized water and anhydrous ethanol in a volume ratio of 7:

3. Step 3, Pretreatment of the transparent substrate: The substrate was treated with a UV ozone cleaner for 5 minutes to enhance its surface hydrophilicity, resulting in a pretreated substrate. Step 4, Preparation of silver nanowire / gum arabic composite film: A silver nanowire solution is coated onto a pretreated substrate and cured at 90–120°C for 10–20 min to form a silver nanowire film. Then, an arabic resin solution is coated onto the silver nanowire film and cured at 80–100°C for 10–20 min to form a silver nanowire-arabic resin composite transparent biodegradable conductive film.

2. The method for preparing the silver nanowire-gum arabic composite transparent biodegradable conductive film according to claim 1, characterized in that: In step 3, the substrate material is glass, cellulose, polyethylene terephthalate, polyethylene naphthalate, or polyimide.

3. The method for preparing the silver nanowire-gum arabic composite transparent biodegradable conductive film according to claim 1, characterized in that, The specific steps for cleaning the substrate in step 3 are as follows: ultrasonically clean the substrate for 15-20 minutes in sequence with detergent, deionized water, acetone and isopropanol.

4. The method for preparing the silver nanowire-gum arabic composite transparent biodegradable conductive film according to claim 1, characterized in that: In step 4, the coating method is blade coating, Mayer rod coating, slot coating, spraying, or spin coating.

5. A transparent and biodegradable conductive film of silver nanowire-gum arabic composite prepared by any one of the preparation methods in claims 1-4.

6. The application of the silver nanowire-gum arabic composite transparent biodegradable conductive film as described in claim 5 in flexible transparent electrodes, implantable devices, organic light-emitting diodes, organic photovoltaics, or environmentally friendly packaged electronic products.

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