Method for preparing ice crack-shaped flexible transparent electrode based on silicon substrate and application thereof

Abstract

The application belongs to the technical field of conductive electrodes, and provides a method for preparing an ice-crack-shaped flexible transparent electrode based on a silicon substrate and application. The method comprises uniformly applying a hydrophobic solution to the surface of a silicon substrate; vertically applying a one-dimensional metal nanomaterial solution with a concentration ranging from 0.1 mg / ml to 10 mg / ml, a diameter ranging from 10 nm to 200 nm, and a length ranging from 1 um to 500 um to the surface of the silicon substrate after the hydrophobic solution, waiting for the one-dimensional metal nanomaterial solution to volatilize to form an ice-crack-shaped conductive network; coating a liquid high polymer polymer substrate on the ice-crack-shaped conductive network, and waiting for the liquid high polymer polymer substrate to solidify into a flexible conductive film; and peeling off the flexible conductive film and the silicon substrate to obtain an ice-crack-shaped flexible transparent electrode. The ice-crack-shaped flexible transparent electrode has uniform sheet resistance, high stability, and low root mean square roughness, and is suitable for various electronic devices.

Description

Technical Field

[0001] This invention belongs to the field of conductive electrode technology, and particularly relates to a method and application for preparing an ice-crack-shaped flexible transparent electrode based on a silicon substrate. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Flexible transparent electrodes (FTEs) possess high light transmittance, low sheet resistance, and good mechanical flexibility, making them widely used in various electronic devices (such as electric heaters, electromagnetic shielding films, and wearable sensors). Among these, ice-crack-like flexible transparent electrodes exhibit significantly better performance (including photoelectric properties, electrothermal stability, chemical stability, and mechanical stability) than randomly arranged one-dimensional metal nanomaterials. While silicon substrates offer advantages for fabricating flexible transparent electrodes due to their extremely smooth and flat surface, and one-dimensional metal nanomaterials are a novel type of flexible transparent conductive material capable of achieving efficient charge transport and excellent conductivity, the advantages of using silicon substrates for flexible transparent electrodes lie in their extremely smooth and flat surface.

[0004] However, the inventors discovered the following technical challenges in using silicon substrates and one-dimensional metal nanomaterials to fabricate ice-crack-like flexible transparent electrodes:

[0005] (1) One-dimensional metal nanomaterial conductive electrodes have problems such as poor stability and non-uniform sheet resistance in practical applications.

[0006] (2) The contact angle of pure water on the silicon substrate is 38.5°. When the one-dimensional metal nanomaterial solution is applied to the silicon substrate by drop coating, scraping or spraying, the droplets cannot be pinned due to the small contact angle, making it difficult to form ice crack-shaped conductive electrodes. Summary of the Invention

[0007] To address the technical problems mentioned above, this invention provides a method and application for fabricating an ice-crack-shaped flexible transparent electrode based on a silicon substrate. The process for fabricating the ice-crack-shaped flexible transparent electrode based on a silicon substrate is simple, and the fabricated ice-crack-shaped flexible transparent electrode has uniform sheet resistance, low surface roughness, and high stability.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] The first aspect of the present invention provides a method for fabricating an ice-crack-like flexible transparent electrode based on a silicon substrate.

[0010] In one or more embodiments, a method for fabricating an ice-crack-like flexible transparent electrode based on a silicon substrate includes:

[0011] The hydrophobic solution is evenly applied to the surface of the silicon substrate;

[0012] A one-dimensional metal nanomaterial solution with a concentration range of 0.1 mg / ml–10 mg / ml, a diameter range of 10–200 nm, and a length range of 1–500 μm was applied vertically to the surface of a silicon substrate coated with a hydrophobic solution. The solution was allowed to evaporate to form an ice-crack-like conductive network.

[0013] A liquid polymer substrate is coated onto the ice-crack-like conductive network, and the liquid polymer substrate is then cured into a flexible conductive film.

[0014] The flexible conductive film is peeled off from the silicon substrate to obtain an ice-crack-like flexible transparent electrode.

[0015] When the concentration of the one-dimensional metal nanomaterial solution is too high, it means that each droplet contains a greater number of silver nanowires. This results in a greater capillary force required to drive the silver nanowires to form an ice-crack-like conductive electrode. Beyond a certain range, the capillary force is insufficient to drive the silver nanowires to form this structure. Experiments showed that the maximum concentration was 10 mg / ml. When the concentration is too low, it has no effect on the formation of the ice-crack-like conductive electrode structure. However, because the concentration is too low, the amount of silver nanowires in the droplet is too small, requiring too many applications to form the ice-crack-like conductive electrode, leading to low efficiency. Experiments showed that the lower concentration limit was 0.1 mg / ml.

[0016] When silver nanowires are longer and have a larger diameter, each nanowire is heavier. The ice-crack structure of silver nanowires is driven by capillary forces generated by solvent evaporation. As the nanowires become thicker and longer, the required driving force is even stronger. If this driving force exceeds the limit provided by solvent evaporation, the ice-crack structure cannot be formed. Conversely, when the length and diameter of silver nanowires are smaller, each nanowire is lighter, requiring less capillary force and correspondingly lower requirements for solvent volatility. However, shorter nanowires result in a greater number of nanowires needed to create a flexible electrode of the same size. This increases the number of nanowire intersections per unit area, which can easily lead to high junction resistance and electrothermal instability.

[0017] As one embodiment of the first aspect of the present invention, the hydrophobic water solution is at least one of Arcelor invisible waterproofing agent and SINWE electronic nano waterproofing coating.

[0018] The advantages of the above technical solution are that both Arcelor invisible waterproofing agent and SINWE electronic nano waterproof coating contain esters and lipids. Lipids are immiscible with water, so they can increase the contact angle. At the same time, the hydrophobic solution has a certain viscosity, which can hinder the movement of droplets and ensure that the droplets can be pinned to the droplet surface, which is conducive to the formation of ice crack structure.

[0019] As one embodiment of the first aspect of the present invention, the hydrophobic water solution is applied to the surface of the silicon substrate at least twice until the hydrophobic water solution on the surface of the silicon substrate is uniform.

[0020] The advantages of the above technical solution are that the effective components of the hydrophobic solution are mainly lipids and esters. If the coating is uneven, some areas may form ice-crack-like conductive electrodes, but the overall sheet resistance of the conductive electrode will be uneven, affecting its conductivity and stability. When the sheet resistance of the conductive electrode is uneven, the area with lower sheet resistance will have a larger current after energizing, which is more likely to generate more Joule heat and cause the electrode to overheat and be damaged. After applying the first hydrophobic solution, some areas may still exhibit unevenness. Applying a second hydrophobic solution makes the hydrophobic layer on the entire surface uniform in thickness, resulting in a more uniform sheet resistance for the overall ice-crack-like conductive electrode.

[0021] In one embodiment of the first aspect of the present invention, the silicon substrate has a thickness of 100 μm-1 cm and an area of ​​0.1 cm². 2 -50cm 2 .

[0022] The advantage of the above technical solution is that the silicon substrate provides a surface with a certain tension and low surface energy for the formation of ice-crack-like structures in one-dimensional metal nanomaterials.

[0023] As one embodiment of the first aspect of the present invention, a one-dimensional metal nanomaterial solution is sprayed onto the surface of a silicon substrate after a hydrophobic aqueous solution has been applied using a spray gun. The nozzle of the spray gun has a diameter of 0.1-10 mm, the nozzle is 1-100 cm away from the silicon substrate, and the carrier gas is an inert gas.

[0024] The advantage of the above technical solution is that the size of the ice crack structure can be adjusted by the pressure of the carrier gas, the nozzle size, and the viscosity of the fluid. The higher the pressure of the carrier gas and the smaller the nozzle size, the easier it is to disperse the one-dimensional metal nanomaterial solution into small droplets. When these small droplets are sprayed onto the substrate, the ice crack size obtained after the solvent evaporates and dries will be even smaller. Similarly, when the concentration of the one-dimensional metal nanomaterial solution is low, that is, when the viscosity of the fluid is low, the carrier gas is more likely to disperse the solution into small droplets, resulting in a smaller ice crack structure.

[0025] As one embodiment of the first aspect of the present invention, a liquid polymer substrate is coated onto the ice-crack-shaped conductive network using a spin coating method.

[0026] The advantage of the above technical solution is that the thickness of the flexible substrate and the ice-crack-shaped flexible transparent electrode can be easily adjusted by using spin coating.

[0027] In one embodiment of the first aspect of the present invention, the thickness of the coated liquid polymer substrate is 10-1000 μm.

[0028] The advantage of the above technical solution is that the thickness can ensure the optical stability of the ice-crack-shaped flexible transparent electrode.

[0029] As one embodiment of the first aspect of the present invention, the liquid polymer substrate is cured by heating, with the curing heating temperature being 60-350°C and the heating time being 20-120 min.

[0030] The advantage of the above technical solution is that by controlling the heating temperature and time, the solvent in the liquid polymer substrate is dried, and because the internal molecular chains of the polymer change at high temperature, the molecular chains are more closely connected, ultimately forming a polymer film, thereby improving the optical stability of the ice-crack-shaped flexible transparent electrode.

[0031] A second aspect of the present invention provides an application of a method for fabricating an ice-crack-like flexible transparent electrode based on a silicon substrate.

[0032] In one or more embodiments, an ice-crack-shaped flexible transparent electrode prepared by the method described above for preparing an ice-crack-shaped flexible transparent electrode based on a silicon substrate is applied in an electronic device.

[0033] The beneficial effects of this invention are:

[0034] (1) This invention utilizes silicon substrate and one-dimensional metal nanomaterials to prepare ice-crack-shaped flexible transparent electrodes. It comprehensively utilizes the flatness of silicon substrate and the high conductivity and transmittance of one-dimensional metal nanomaterials. The ice-crack-shaped conductive network obtained during the preparation process has a more uniform sheet resistance distribution and a lower surface roughness compared with the conductive network formed by random arrangement of one-dimensional metal nanomaterials, which can make it more stable in flexible electronic devices. Moreover, one-dimensional metal nanomaterials have high conductivity and transmittance, and polymer substrate materials also have excellent transmittance. Therefore, the flexible transparent electrode finally prepared has excellent photoelectric performance.

[0035] (2) In the process of preparing an ice-crack-like flexible transparent electrode based on a silicon substrate, the present invention uniformly coats the surface of the silicon substrate with a hydrophobic aqueous solution. This can increase the contact angle to 100.3° without affecting the substrate structure. When the one-dimensional metal nanomaterial solution is applied to the substrate, the solution can be pinned on the substrate. At the same time, the solvent in the solution evaporates. The solvent evaporation rate at the edge of the solution is greater than that at the middle of the solution, which will generate a capillary force towards the edge. This capillary force is much greater than the Marangoni backflow to the middle of the solution caused by the surface tension gradient, thereby driving the one-dimensional metal nanomaterial to be deposited at the edge of the droplet. Finally, a conductive electrode with an ice-crack-like arrangement structure of one-dimensional metal nanomaterial is prepared.

[0036] (3) The process of preparing ice-crack-shaped flexible transparent electrodes based on silicon substrates in this invention is simple and can be prepared on a large scale, so it can be used for industrial production. Furthermore, the size of the ice-crack-shaped conductive network can be easily adjusted by adjusting the parameters of spraying, dripping, and scraping, thereby improving the conductivity according to the application purpose.

[0037] (4) The ice-crack-like conductive network of the present invention has large-sized knots and bundles, and has lower surface energy, so it also has higher stability. It can be applied to electronic devices that work in extreme environments, such as aerospace and metallurgical equipment in high-temperature working environments, or chemical equipment containing chemical corrosion. It has significant advantages over conductive thin film materials in the prior art.

[0038] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0039] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0040] Figure 1 This is a schematic diagram of a method for fabricating an ice-crack-like flexible transparent electrode based on a silicon substrate, provided by the present invention.

[0041] Figure 2 This is an optical microscope image of the silicon-based ice-crack-like conductive network of Embodiment 1 of the present invention;

[0042] Figure 3 This is an atomic force microscopy test pattern of the flexible transparent electrode of Embodiment 1 of the present invention;

[0043] Figure 4 This is a test spectrum of the electrical and thermal stability of the flexible transparent electrode of Embodiment 1 of the present invention;

[0044] Figure 5 This is the sheet resistance uniformity spectrum of the flexible transparent electrode in Embodiment 2 of the present invention;

[0045] Figure 6 This is a performance diagram of the electric heater based on a flexible transparent electrode according to Embodiment 3 of the present invention;

[0046] Figure 7 This is an optical microscope image of the conductive network on the surface of the glass substrate in Comparative Example 1 of this invention. Detailed Implementation

[0047] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0048] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, 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.

[0049] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0050] Terminology Explanation:

[0051] Ice-crack-like structure: When a solution of one-dimensional metal nanomaterials of a certain concentration is deposited on a substrate by spraying, dripping, or scraping, the evaporation rate in the center of the droplet is lower than that at the edge. The resulting capillary flow suppresses the Malegoni effect, causing the one-dimensional metal nanomaterials in the solution to be driven from the center to the edge, producing an "ice-crack-like structure". The "ice-crack-like structure" mentioned in this application refers to the continuous ring structure formed by one-dimensional metal nanomaterials on the surface of the substrate material.

[0052] Silicon substrate: n-type silicon wafer or p-type silicon wafer.

[0053] Figure 1 This is a schematic flowchart of a method for fabricating an ice-crack-like flexible transparent electrode based on a silicon substrate, as provided by the present invention. Figure 1 As shown in the figure, a method for fabricating an ice-crack-like flexible transparent electrode based on a silicon substrate according to an embodiment of the present invention includes:

[0054] Step 1: Apply the hydrophobic solution evenly to the surface of the silicon substrate;

[0055] Step 2: Apply a one-dimensional metal nanomaterial solution with a concentration range of 0.1 mg / ml–10 mg / ml, a diameter range of 10–200 nm, and a length range of 1–500 μm vertically to the surface of the silicon substrate after coating with a hydrophobic solution, and wait for the one-dimensional metal nanomaterial solution to evaporate to form an ice-crack-like conductive network.

[0056] Step 3: Coat the liquid polymer substrate onto the ice-crack-like conductive network, and allow the liquid polymer substrate to solidify into a flexible conductive film;

[0057] Step 4: Peel the flexible conductive film from the silicon substrate to obtain an ice-crack-shaped flexible transparent electrode.

[0058] This embodiment utilizes a silicon substrate and one-dimensional metal nanomaterials to fabricate an ice-crack-shaped flexible transparent electrode. It comprehensively leverages the flatness of the silicon substrate and the high conductivity and transmittance of the one-dimensional metal nanomaterials. Compared with the conductive network formed by the random arrangement of one-dimensional metal nanomaterials, the ice-crack-shaped conductive network obtained during the fabrication process has a more uniform sheet resistance distribution and a lower surface roughness, which allows it to be more stably applied in flexible electronic devices. Moreover, the one-dimensional metal nanomaterials have high conductivity and transmittance, and the polymer substrate material also has excellent transmittance. Therefore, the final fabricated flexible transparent electrode has excellent photoelectric performance.

[0059] In step 1, the silicon substrate is an n-type silicon or a p-type silicon substrate.

[0060] In one or more embodiments, the silicon substrate has a thickness of 100 μm-1 cm and an area of ​​0.1 cm². 2 -50cm 2 Among them, silicon-based substrates are used to provide a surface with certain tension and low surface energy for the formation of ice-crack-like structures in one-dimensional metal nanomaterials.

[0061] The hydrophobic aqueous solution in step 1 can be prepared according to the actual situation, and will not be described in detail here.

[0062] In step 1, a hydrophobic aqueous solution is uniformly coated on the surface of a silicon substrate. This increases the contact angle to 100.3° without affecting the substrate structure. When the one-dimensional metal nanomaterial solution is applied to the substrate, the solution can pin the substrate. At the same time, the solvent in the solution evaporates. The solvent evaporation rate at the edge of the solution is greater than that at the center of the solution, which generates a capillary force towards the edge. This capillary force is much greater than the Marangoni backflow to the center of the solution caused by the surface tension gradient. This causes the one-dimensional metal nanomaterial to be deposited at the edge of the droplet, and finally a conductive electrode with an ice crack-like arrangement structure of one-dimensional metal nanomaterial is prepared.

[0063] In step 2, the one-dimensional metal nanomaterial solution includes, but is not limited to, silver nanowires, copper nanowires, and gold nanowires. Different types of metal nanowires have different lengths and diameters. In particular, conventional silver nanowires have larger diameters and longer lengths, resulting in greater nanowire mass. Conventional parameters are insufficient to drive the nanowires and form flexible transparent electrodes with ice-crack patterns. Therefore, it is necessary to increase the gas pressure and enhance the capillary force to enable the nanowires to deposit and form ice-crack-shaped electrodes.

[0064] In a preferred embodiment, the concentration of the one-dimensional metal nanomaterial solution is 0.001-10 mg / ml. The ice-crack-like conductive network formed by the one-dimensional metal nanomaterial solution within this concentration range exhibits high stability.

[0065] In step 2, the one-dimensional metal nanomaterials are applied by methods including but not limited to spraying, dripping, or scraping.

[0066] Preferably, a one-dimensional metal nanomaterial solution with a concentration ranging from 0.1 mg / ml to 10 mg / ml, a diameter ranging from 10 to 200 nm, and a length ranging from 1 to 500 μm is applied vertically to the surface of a silicon substrate after the aqueous solution has been sprayed; wherein, during the spraying process, the normal of the one-dimensional metal nanomaterial solution column is perpendicular to the surface of the silicon substrate. This ensures the formation of a flexible transparent electrode with a uniform sheet resistance and an ice-crack-like appearance.

[0067] For example, a one-dimensional metal nanomaterial solution is sprayed onto the surface of a silicon substrate coated with a hydrophobic solution using a spray gun. The nozzle diameter of the spray gun is 0.1-10 mm, the distance from the nozzle to the silicon substrate is 1-100 cm, and the carrier gas is an inert gas. The inert gas includes, but is not limited to, high-purity air, nitrogen, and argon.

[0068] The size of the ice crack structure can be adjusted by the pressure of the carrier gas, the nozzle size, and the viscosity of the fluid. The higher the pressure of the carrier gas and the smaller the nozzle size, the easier it is to disperse the one-dimensional metal nanomaterial solution into small droplets. These droplets are then sprayed onto the substrate, and the ice crack size is even smaller after the solvent evaporates and dries. Similarly, when the concentration of the one-dimensional metal nanomaterial solution is low, i.e., the viscosity of the fluid is low, the carrier gas is more likely to disperse the solution into small droplets, resulting in a smaller ice crack structure.

[0069] Furthermore, the solvent's volatility is crucial for spraying. The faster the solvent evaporates, the stronger the capillary force generated, which helps deposit silver nanowires at the solution edges. If the solvent's volatility is too high, the resulting ice-crack-like conductive electrode will have disconnected sections. This is because excessive volatility causes most of the nanowires to deposit at the intersections of multiple droplets—the intersections of ice cracks. Conversely, insufficient volatility will prevent the droplets from drying properly, making it difficult to generate the capillary force needed to drive the nanowires to deposit at the droplet edges. Air pressure during spraying is also a factor affecting the rapid drying of the droplets. Higher air pressure results in faster gas flow and quicker drying, but excessive pressure can disperse the silver nanowires. Therefore, the air pressure range is 0.01-1 MPa.

[0070] In step 3, a liquid polymer substrate is coated onto the ice-crack-shaped conductive network using a spin-coating method. Spin-coating allows for easy adjustment of the thickness of the flexible substrate and the ice-crack-shaped flexible transparent electrode. For example, the spin coater speed can be 10-2000 rpm, and the spin-coating time can be 1-200 s.

[0071] Among them, the polymer substrates include, but are not limited to, colorless polyimide (CPI) film, polyimide (PI) film, polyester (PET) film, polydimethylsiloxane (PDMS) film, styrene rubber (SEBS) film, polytetrafluoroethylene (PTFE) film, and polyvinyl chloride (PVC) film.

[0072] When the polymer substrate is a colorless polyimide film, it has good chemical stability, electrical stability and thermal stability, as well as excellent optical properties, which will improve the lifespan, stability and optoelectronic performance of the device.

[0073] The thickness of the coated liquid polymer substrate is 10-1000 μm. This thickness ensures the optical stability of the ice-crack-like flexible transparent electrode. Those skilled in the art can select an appropriate thickness according to the intended use; for larger thicknesses, multiple coatings can be applied.

[0074] The liquid colorless polyimide flexible substrate has a solid content of 5-50%.

[0075] For example, a liquid polymer substrate can be cured by heating at a temperature of 60-350℃ for 20-120 minutes. By controlling the heating temperature and time, the solvent in the liquid polymer substrate is dried out. Furthermore, due to the changes in the internal molecular chains of the polymer at high temperatures, the molecular chains become more tightly connected, ultimately forming a polymer film, which improves the optical stability of the ice-crack-like flexible transparent electrode.

[0076] The purpose of coating a substrate with a liquid polymer is to encapsulate one-dimensional metallic nanomaterials. When one-dimensional metallic nanomaterials are applied to a silicon substrate, the adhesion between the nanomaterial and the substrate is weak, and the nanomaterials easily detach. Therefore, a liquid polymer coating method is used. The liquid polymer is dropped onto the surface of the silicon substrate, and then the substrate is rotated using a spin coater. Centrifugal force is used to evenly spread the liquid polymer on the substrate, thus encapsulating the one-dimensional metallic nanomaterials. The coating should be bubble-free and of uniform thickness.

[0077] In step 4, the experimenter can peel the thin film off the silicon substrate by using tweezers to pry open a corner.

[0078] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0079] Example 1

[0080] In this embodiment, a flexible transparent electrode with an ice-crack pattern on a silicon substrate is provided. The electrode is fabricated as follows:

[0081] (1) The hydrophobic aqueous solution is uniformly coated on the surface of the silicon substrate. Silver nanowires with diameters of 30 nm and lengths of 20 μm are selected and added to methanol to prepare an Ag NWs solution with a concentration of 0.5 mg / ml. The Ag NWs solution is added to a spray gun with a nozzle diameter of 0.3 mm and a spraying distance of 10 cm. The Ag NWs solution is sprayed onto a 3 cm × 3 cm n-type silicon substrate, and the sheet resistance is controlled to be about 30 Ω / sq. After the solution evaporates, an ice-crack-like conductive network is formed.

[0082] (2) Place the n-type silicon substrate with ice crack structure on a spin coater and spin coat the liquid colorless polyimide solution onto the n-type silicon substrate with Ag NWs ice crack structure at a speed of 500 rpm.

[0083] (3) The liquid colorless polyimide and the n-type silicon substrate coated with Ag NWs ice crack structure conductive network are placed in an oven and heated at 100°C for 60 minutes to solidify the above structure into a film.

[0084] (4) After the silicon substrate coated with Ag NWs ice crack conductive network and the solidified flexible conductive film have cooled, the CPI layer and Ag NWs layer are peeled off from the silicon substrate to obtain the flexible transparent electrode.

[0085] In this embodiment, the surface roughness of the conductive film described in Example 1 was tested. Figure 2 It is an optical microscope image of a silicon-based ice-crack-like conductive network; Figure 3This is an atomic force microscopy (AFM) image of the flexible transparent electrode of Embodiment 1 of the present invention. Figure 3 As can be seen, the root mean square roughness (RMS) of the flexible transparent electrode based on an n-type silicon substrate described in Example 1 is 4.57 nm. This is mainly due to the atomic-level roughness of the n-type silicon substrate itself. Furthermore, its electrothermal stability was also tested. Figure 4 As shown, it can withstand high temperatures of 340℃ and high voltages of 8V without significant changes in sheet resistance, exhibiting excellent electrothermal stability. This allows it to be used in harsh environments, broadening its application range.

[0086] Example 2

[0087] In this embodiment, a flexible transparent electrode with an ice-crack pattern on a silicon substrate is provided. The electrode is fabricated as follows:

[0088] (1) The hydrophobic water solution is uniformly coated on the surface of the silicon substrate. Silver nanowires with diameters of 10 nm and lengths of 20 μm are selected and added to IPA to prepare an Ag NWs solution with a concentration of 0.5 mg / ml. The Ag NWs solution is added to a spray gun with a nozzle diameter of 0.3 mm and a spraying distance of 15 cm. The Ag NWs solution is sprayed onto a 6 cm × 6 cm n-type silicon substrate, and the sheet resistance is controlled to be about 7.5 Ω / sq. After the solution evaporates, an ice-crack-like conductive network is formed.

[0089] (2) Place the n-type silicon substrate with ice crack structure on a spin coater and spin coat the liquid colorless polyimide solution onto the n-type silicon substrate with Ag NWs ice crack structure at a speed of 900 rpm.

[0090] (3) The liquid colorless polyimide and the n-type silicon substrate coated with Ag NWs ice-crack structure conductive network were placed together in an oven and heated at 120°C for 30 minutes to solidify the above structure into a film.

[0091] (4) After the silicon substrate coated with Ag NWs ice crack conductive network and the solidified flexible conductive film have cooled, the CPI layer and Ag NWs layer are peeled off from the silicon substrate to obtain the flexible transparent electrode.

[0092] This embodiment also verifies the electrical performance of the sheet resistance uniformity of the conductive thin film described in Example 1, such as... Figure 5 As shown, the sheet resistance uniformity is good, with a maximum sheet resistance variation of about 5%, which is comparable to high-quality ITO / PET.

[0093] Example 3

[0094] In this embodiment, a flexible transparent electrode with an ice-crack pattern on a silicon substrate is provided. The electrode is fabricated as follows:

[0095] (1) The hydrophobic aqueous solution is uniformly coated on the surface of the silicon substrate. Silver nanowires with diameters of 80 nm and lengths of 60 μm are selected and added to ethanol to prepare an Ag NWs solution with a concentration of 1 mg / ml. The Ag NWs solution is added to a spray gun with a nozzle diameter of 0.8 mm and a spraying distance of 50 cm. The Ag NWs solution is sprayed onto a 2 cm × 2 cm n-type silicon substrate, and the sheet resistance is controlled to be about 20 Ω / sq. After the solution evaporates, an ice-crack-like conductive network is formed.

[0096] (2) Place the n-type silicon substrate with ice crack structure on a spin coater and spin coat the liquid colorless polyimide solution onto the n-type silicon substrate with Ag NWs ice crack structure at a speed of 800 rpm.

[0097] (3) The liquid colorless polyimide and the n-type silicon substrate coated with Ag NWs ice crack structure conductive network are placed together in an oven and heated at 130°C for 45 minutes to solidify the above structure into a film.

[0098] (4) After the silicon substrate coated with Ag NWs ice crack conductive network and the solidified flexible conductive film have cooled, the CPI layer and Ag NWs layer are peeled off from the silicon substrate to obtain the flexible transparent electrode.

[0099] Next, conductive silver paste was applied to both ends of the electrodes to increase electrical contact. After curing, a DC voltage was applied across the electrodes using a source meter to test the performance of the electric heater. Under a specific driving voltage, Joule heating is generated due to the inelastic collisions between accelerated electrons and phonons. Steady-state saturation temperature, response / recovery time, and heating stability are several important indicators for evaluating heater performance, such as... Figure 6 As shown, the flexible transparent electric heater has good Joule heating performance.

[0100] Comparative Example

[0101] This comparative example provides a transparent electrode fabricated on a glass substrate. As is known in the art, glass is a silicate nonmetallic material formed by melting silicon dioxide with other chemical substances, and it has a greater surface tension than silicon-based substrates. In this comparative example, glass is used as the substrate material, and other preparation methods are the same as in Example 1. The resulting conductive film is as follows: Figure 7 As shown, the solidified silver nanoparticles can only be stacked in a linear fashion, and the "ice crack" structure cannot be obtained, resulting in a significant reduction in their conductivity.

[0102] During the experiment, various other similar materials or substrate materials with low surface tension were tried, but none of them could achieve the same stable and repeatable effect as silicon substrates.

[0103] In one or more embodiments, an ice-crack-shaped flexible transparent electrode prepared by the method described above for preparing an ice-crack-shaped flexible transparent electrode based on a silicon substrate is also provided, which is applied in electronic devices.

[0104] The electronic devices here can be used in the fields of information, energy, medical and defense.

[0105] Among these, information-related applications include, but are not limited to, the preparation of electronic displays, electronic storage materials, touch materials, and printing equipment.

[0106] Applications in the medical field include, but are not limited to, the manufacture of flexible wearable medical devices.

[0107] Applications in the energy sector include, but are not limited to, thin-film solar cells, metallurgical equipment, and heat treatment equipment.

[0108] Applications in the defense sector include, but are not limited to, applications in the aerospace field.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating an ice-crack-like flexible transparent electrode based on a silicon substrate, characterized in that, include: Apply the hydrophobic solution to the surface of the silicon substrate at least twice until the hydrophobic solution is uniform on the surface of the silicon substrate. The hydrophobic solution is at least one of Arcelor invisible waterproofing agent and SINWE electronic nano waterproofing coating; A one-dimensional metal nanomaterial solution with a concentration range of 0.5 mg / ml-10 mg / ml, a diameter range of 10-200 nm, and a length range of 1-500 μm was vertically applied to the surface of a silicon substrate after the solution was hydrophobic. The solution was allowed to evaporate to form an ice-crack-like conductive network. A one-dimensional metal nanomaterial solution is sprayed onto the surface of a silicon substrate coated with a hydrophobic solution using a spray gun. The nozzle diameter of the spray gun is 0.1-10 mm, the distance from the nozzle to the silicon substrate is 1-100 cm, and the carrier gas is an inert gas. When the one-dimensional metal nanomaterial solution is applied to the substrate, the solution can pin the substrate. At the same time, the solvent in the solution evaporates. The solvent evaporation rate at the edge of the solution is greater than that at the center of the solution, which generates a capillary force towards the edge. This capillary force is much greater than the Marangoni backflow to the center of the solution caused by the surface tension gradient, thereby driving the one-dimensional metal nanomaterial to deposit at the edge of the droplet. Finally, a conductive electrode with an ice crack-like arrangement structure of one-dimensional metal nanomaterials is prepared. A liquid polymer substrate is coated on the ice-crack-like conductive network, and the liquid polymer substrate is cured into a flexible conductive film. The liquid polymer substrate is cured by heating at a temperature of 60-350℃ for 20-120 minutes. The flexible conductive film is peeled off from the silicon substrate to obtain an ice-crack-like flexible transparent electrode.

2. The method for fabricating an ice-crack-like flexible transparent electrode based on a silicon substrate as described in any one of claims 1, characterized in that, The thickness of the silicon substrate is 100 μm-1 cm.

3. The method for fabricating an ice-crack-like flexible transparent electrode based on a silicon substrate as described in claim 1, characterized in that, The area of ​​the silicon substrate is 0.1 cm². 2 -50cm 2 .

4. The method for fabricating an ice-crack-like flexible transparent electrode based on a silicon substrate as described in claim 1, characterized in that, A liquid polymer substrate was coated onto the ice-crack-shaped conductive network using a spin-coating method.

5. The method for fabricating an ice-crack-like flexible transparent electrode based on a silicon substrate as described in claim 1, characterized in that, The thickness of the coated liquid polymer substrate is 10-1000 μm.

6. An ice-crack-shaped flexible transparent electrode prepared by the method for preparing an ice-crack-shaped flexible transparent electrode based on a silicon substrate as described in any one of claims 1-5, characterized in that, It is used in electronic devices.

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