Flexible two-dimensional electrode based on ultrathin parylene substrate and preparation method and application thereof

Abstract

The invention discloses a flexible two-dimensional electrode preparation technology based on an ultrathin parylene substrate. The flexible two-dimensional electrode preparation technology comprises the following steps: preparing an MXene solution with a certain concentration; forming an MXene film on the surface of an ITO (Indium Tin Oxide) flexible substrate by using the MXene solution through an electro-deposition method; uniformly depositing a parylene material layer on the surface of the MXene film by using a parylene coating material to form a parylene film, and obtaining a parylene / MXene / ITO / parylene film composite structure; and stripping the composite film of the parylene film / MXene film from the surface of the ITO flexible substrate to finally obtain the flexible two-dimensional electrode based on the ultrathin parylene substrate. The preparation of the self-assembled film of MXene is realized by using the functional group of MXene and the external electric field acting force, and the flexible two-dimensional electrode of the ultrathin parylene substrate, which is antioxidant and stable in environment, is obtained by virtue of the compact pinhole-free structure, excellent chemical inertness and high barrier property of the parylene film.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible two-dimensional electrodes, and in particular to a flexible two-dimensional electrode based on an ultrathin parylene substrate, and a preparation method and application thereof. Background Art

[0002] With the increasing demand for miniaturization, high integration, and complex environmental applications of electronic devices, the development of high-performance, flexible conductive electrode materials has become crucial. At the same time, material protection has also become a top priority. Parylene, a poly(para-xylene) polymer, has been widely used in electronic packaging, medical devices, aerospace, and other fields since its development by Union Carbide in the United States in the 1960s. Its unique chemical vapor deposition (CVD) process and excellent protective properties have made it widely used in electronic packaging, medical devices, aerospace, and other fields. Its fully conformable, pinhole-free, and high-barrier properties make it one of the most effective moisture-proof, mildew-proof, and corrosion-resistant coating materials currently available. Furthermore, due to its intrinsic flexibility, this material shows great potential in the preparation of flexible substrates.

[0003] In recent years, with the rapid development of 5G communications, the Internet of Things (IoT), and wearable devices, the demand for flexible electrodes in flexible electronic devices has been increasing, and the demand for their complex functions has also been increasing. For example, flexible electronic devices require coatings that combine high flexibility, bend resistance, and low stress; biomedical implants must meet long-term biocompatibility and sterilization stability; and aerospace equipment must withstand extreme temperatures, radiation, and vacuum environments. Traditional coating materials (such as epoxy resins and polyurethanes) have difficulty meeting these requirements due to problems such as pinholes, residual stress, and insufficient temperature resistance. Parylene, with its unique molecular structure and CVD process, has become an ideal choice for solving these technical bottlenecks. According to market research firm GrandViewResearch, the global parylene coating market exceeded US$550 million in 2022, and is expected to grow at a compound annual growth rate (CAGR) of 8.7% from 2023 to 2030. This growth is primarily driven by the demand for protection in consumer electronics, new energy batteries, and medical equipment.

[0004] MXene materials, a novel class of two-dimensional transition metal carbides or nitrides, show great potential for application in flexible electronics due to their unique layered structure, high electrical conductivity, excellent mechanical flexibility, and abundant surface functional groups. However, the research and application of conductive MXene electrodes still face several key challenges. First, the balance between film uniformity and production efficiency in large-scale fabrication processes remains unresolved. Second, the insufficient oxidation stability of MXene materials in air limits their reliability in long-term applications. Furthermore, the mechanisms by which existing packaging and transfer technologies affect device electrical properties require further clarification. Summary of the Invention

[0005] To address the above technical issues, the present invention provides a flexible two-dimensional electrode based on an ultrathin parylene substrate, as well as a preparation method and application thereof. The present invention achieves large-area, uniform, and controllable growth of MXene films on rigid substrates through electric-field-driven deposition technology, and combines parylene thin-film coating technology to achieve lossless transfer of two-dimensional MXene. Furthermore, the encapsulation technology of the parylene thin-film coating effectively enhances its antioxidant capacity and environmental stability. The focus is on three core areas: first, optimizing the MXene solution formulation by adding surfactants and determining the physical parameters for electric-field deposition; second, systematically characterizing the film morphology, uniformity, and flexibility; and third, exploring the effects of parylene encapsulation and lossless stripping on the transfer and environmental stability of two-dimensional MXene.

[0006] The first object of the present invention is to provide a method for preparing a flexible two-dimensional electrode based on an ultrathin parylene substrate, comprising the following steps:

[0007] MXene precursor dispersion was prepared using surfactant and Ti3C2:

[0008] The MXene precursor dispersion is electroplated to form a MXene film on the surface of the ITO flexible substrate:

[0009] A parylene coating material is uniformly deposited on the surface of the MXene film to form a parylene film layer, which completely wraps the flexible substrate with the MXene film on its surface, forming a composite structure of parylene / MXene / ITO / parylene film, thereby achieving the encapsulation of the flexible two-dimensional electrode;

[0010] An incision is made at one end of the composite structure using laser cutting, and then the composite film of the parylene / MXene film close to the side of the ITO flexible substrate is peeled off from the incision together, finally obtaining the flexible two-dimensional electrode based on the ultra-thin parylene substrate.

[0011] In some embodiments of the present invention, the process of forming MXene thin films by electrodeposition is divided into three stages. The first stage: MXene is dispersed in DMAC solution, and a large amount of OH groups are present on its surface. - and F -Anionic groups such as surfactants are added to enhance the uniformity of material dispersion. Under the action of the electric field, the disordered MXene gradually tends to order and dissociates toward the positive electrode, forming an ordered MXene. The second stage: The ordered MXene is affected by the van der Waals force, and the layers are tightly attached to each other, thereby forming a multi-layer structure. The third stage: The MXene multi-layer structure continues to move toward the positive electrode under the drive of the electric field. When it reaches the surface of the ITO flexible substrate of the positive electrode, it adheres to the ITO flexible substrate by van der Waals force and self-assembles on the surface of the ITO flexible substrate, making the MXene layers more tightly bonded, thereby completing the preparation of the MXene film.

[0012] In the present invention, because the bonding strength between the MXene film and the ITO flexible substrate is much weaker than that between the MXene film and the parylene film, the composite film of the MXene film and the parylene film can be physically peeled off from the ITO flexible substrate. This ultimately yields the flexible two-dimensional electrode based on the ultrathin parylene substrate.

[0013] In some embodiments of the present invention, the concentration of the MXene solution is 5-20 mg / mL. In the present invention, the MXene solution needs to be shaken to ensure solution homogeneity. Due to the high surface energy and van der Waals forces, MXene nanosheets are prone to agglomeration or sedimentation during standing. Therefore, the addition of a surfactant ensures solution homogeneity and prevents local concentration differences from affecting the accuracy of experimental results.

[0014] In some embodiments of the present invention, the ITO flexible substrate is pretreated, and the pretreatment comprises the following steps: cleaning with detergent, deionized water, acetone, and ethanol by ultrasonic treatment for at least 15 minutes each, and drying with a nitrogen gun.

[0015] In some embodiments of the present invention, the voltage of the electrodeposition method is set to 8-10 V and the time is 2 minutes.

[0016] In the present invention, the specific steps of electrodeposition of MXene film are:

[0017] Place the two pretreated ITO substrates in an electrodeposition container with the conductive surfaces facing each other. Add the prepared MXene solution and apply a specific voltage. Under the action of the directional electric field, the MXene sheet molecules move toward the positive electrode and deposit on the ITO substrate. The electrodeposition process lasts 2-30 minutes. By controlling the electrodeposition time, the thickness of the film can be adjusted. Furthermore, the electrodes of the workstation are selected to be 2×2 cm 2 Indium tin oxide layer electrode ITO electrode; the electrode spacing at the left and right ends is 10mm, and the positive and negative electrodes are both ITO electrodes.

[0018] In some embodiments of the present invention, the parylene coating material includes one or more of parylene C powder, parylene N powder, parylene D powder, parylene F powder, and parylene HT powder, and the loading amount of the parylene coating material is 0.1-1 g / cm 2 .

[0019] In some embodiments of the present invention, the instrument process parameters used in the process of uniformly depositing the parylene material layer on the surface of the MXene film are as follows: the temperature is gradually increased from 80°C to 110°C, and the temperature is increased in stages, specifically: 80-94°C stage, each temperature increase of 2°C is maintained for 10-20 minutes; 94-110°C stage, each temperature increase of 2°C is maintained for 10-20 minutes. The temperature during pyrolysis is 180°C; the vacuum degree is 10 -2 Pa.

[0020] In some embodiments of the present invention, the deposition rate of the parylene coating material is 0.5-1 μm / h.

[0021] The preparation process of the parylene coating in the present invention adopts chemical vapor deposition (CVD) technology. The entire process is carried out under vacuum conditions and is mainly divided into three processes: evaporation, cracking, and deposition.

[0022] In the present invention, the parylene encapsulation and stripping specifically include the following steps:

[0023] The electrodeposited MXene film is placed in a parylene CVD device and deposited at room temperature and pressure. The deposition time is controlled to ensure a parylene film thickness of 4-8 μm, achieving uniform, pinhole-free packaging. The deposition rate is controlled at 0.5-1 μm / h to ensure film uniformity and density. After encapsulation, the film is removed, a small incision is made using laser cutting, and the parylene / MXene film layer is peeled off for observation of its morphology and condition.

[0024] The second object of the present invention is to provide a flexible two-dimensional electrode based on an ultra-thin parylene substrate, which is prepared by the above-mentioned preparation method. The flexible two-dimensional electrode has a parylene film as a substrate and a MXene film is provided on the surface of the substrate.

[0025] In some embodiments of the present invention, the thickness of the parylene film is 4-8 μm; the thickness of the MXene film is 5-25 μm; and the total thickness of the flexible two-dimensional electrode is 9-33 μm.

[0026] The third object of the present invention is to provide a flexible electronic device comprising the flexible two-dimensional electrode.

[0027] In the present invention, a pretreated substrate is placed in an electrodeposition container, a prepared MXene solution is added, and a voltage is applied. The MXene sheet molecules move toward the positive electrode and self-assemble and deposit on the ITO substrate, obtaining a uniform MXene self-assembled film. The electrodeposited MXene film is placed in a parylene CVD device, and a uniform and dense parylene film is plated on the MXene film to form a protective layer without blind spots that can cover the sharp edges, cracks, and inner surface of the substrate. A small incision is cut using laser cutting, and the parylene / MXene is peeled off to obtain a flexible two-dimensional electrode with an ultra-thin substrate. The present invention utilizes the functional groups of MXene itself and the external electric field force to achieve the preparation of the MXene self-assembled film. In addition, the dense, pinhole-free structure, excellent chemical inertness, and high barrier properties of the parylene film effectively improve the oxidation resistance and environmental stability of the flexible two-dimensional electrode.

[0028] The oxidation resistance and environmental stability of the present invention refer to preparing functional materials on the ITO electrode, and further preparing a composite structure of parylene / MXene / ITO / parylene film, which is isolated from the outside world, prevents oxidation, and can be stored for a long time.

[0029] The above technical solution of the present invention has the following advantages over the prior art:

[0030] 1. The present invention successfully achieves large-area uniform deposition of MXene sheets on an ITO flexible substrate through electrodeposition technology combined with directional electric field control, successfully solving the problem of balancing film uniformity and production efficiency in large-area preparation processes.

[0031] 2. The composite structure of parylene / MXene / ITO / parylene film provided by the present invention effectively improves the oxidation resistance of MXene material in air and removes the limitation of its reliability in long-term storage.

[0032] 3. The present invention also successfully prepared a flexible MXene composite film based on parylene, realizing the preparation of flexible ultra-thin two-dimensional electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0034] Figure 1 This is a flow chart of the process for preparing a thin film coating using parylene according to an embodiment of the present invention;

[0035] Figure 2 This is a diagram illustrating the types of parylene materials in the prior art;

[0036] Figure 3 Schematic diagram of the electrodeposition process according to an embodiment of the present invention;

[0037] Figure 4 The MXene film loaded on the surface of the ITO substrate obtained after electrodeposition in Example 1 of the present invention;

[0038] Figure 5 Schematic diagram of the unpeeled composite film encapsulated in Example 1 of the present invention;

[0039] Figure 6 Schematic diagram of the bending of the flexible two-dimensional electrode obtained after parylene encapsulation in Example 1 of the present invention;

[0040] Figure 7 Schematic diagram of the encapsulated and peeled composite film in Example 1 of the present invention;

[0041] Figure 8 Atomic force microscope (AFM) images of the composite film prepared at voltages of 6V, 7V, 8V, 9V, and 10V after packaging and peeling;

[0042] Figure 9 This is an atomic force microscope (AFM) image of the composite film prepared by the present invention after being immersed in acid and alkali;

[0043] Figure 10 These are the initial resistance state of the composite film prepared by the present invention and the resistance state after high-temperature thermal oxidation.

[0044] Figure 11 This is a performance diagram of the memristor device prepared based on the ultra-thin flexible conductive electrode of the present invention. DETAILED DESCRIPTION

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0046] Example 1:

[0047] This embodiment provides a flexible two-dimensional electrode preparation technology based on an ultrathin parylene substrate, which specifically includes the following steps:

[0048] Step 1: Clean the ITO substrate coated with an indium tin oxide conductive layer, and ultrasonically wash it with detergent, deionized water, acetone, and anhydrous ethanol for 15 minutes each. Finally, store the washed substrate for later use; prepare a MXene precursor dispersion with a concentration of 5 mg / mL and shake the solution before use.

[0049] The MXene precursor dispersion was prepared by reacting a mixture of TiH2, Al, and TiC at 1450°C for 2 hours under argon. Two-dimensional Ti3C2 was obtained by immersing Ti3AlC2 in 49% hydrofluoric acid (Aladdin Reagent, China) at 60°C for 24 hours. The sample was then washed with deionized water, and the Ti3C2 powder was centrifuged and dried in vacuo at 80°C. For intercalation, 0.5 g of the exfoliated powder was mixed with 10 mL of dimethyl sulfoxide (DMSO, Aladdin Reagent, China) and magnetically stirred at room temperature for 18 hours. The resulting suspension was then washed, the powder was centrifuged, and finally dried in vacuo at 80°C. The powder was dissolved in dimethylacetamide (DMAC, Aladdin Reagent, China), followed by the addition of 0.1 mg / mL of tetrabutylammonium hexafluorophosphate to produce a 5 mg / mL MXene precursor dispersion.

[0050] Step 2: Place the two pretreated ITO substrates in an electrodeposition container with the conductive surfaces facing each other. Add the prepared MXene precursor dispersion and apply a specific 8V. The electrodeposition process lasts for 2 minutes to obtain an ITO substrate with a surface-loaded MXene film. The obtained MXene film is peeled off with the help of a tool, and the surface morphology of the MXene film is observed by atomic force microscopy (AFM) at 25°C and 30% humidity. The results are shown in Figure 2. Figure 8 The AFM height map and peak force error map show ( Figure 8 ), the surface of the MXene film exhibits a uniform lamellar structure with low surface roughness, which facilitates efficient charge carrier transport and effectively prevents leakage current. Ra further decreases to 20.8nm (Rq = 27.4nm). Rq stands for "root mean square roughness," which refers to the root mean square value of the profile height deviation within a sampling length. It reflects the statistical properties of surface roughness; smaller values ​​indicate a smoother surface.

[0051] Step 3. Place the ITO substrate with the MXene film loaded on the surface obtained in step 2 in a parylene CVD device, and use 8g of parylene C powder to deposit the parylene film. The deposition rate is controlled at 0.5μm / h to obtain a composite structure of parylene / MXene / ITO / parylene film. After the encapsulation is completed, select one end of the composite structure and use laser cutting to cut an incision. Then, the parylene / MXene composite film close to the side of the ITO flexible substrate is peeled off from the incision together, and then the parylene film close to the side of the ITO substrate is peeled off from the incision together with the ITO flexible substrate. Finally, a flexible two-dimensional electrode composed of a MXene film layer and a parylene film layer is obtained. In this embodiment, the thickness of the MXene film is 20μm, the thickness of the parylene film is 6.03μm, and the thickness of the composite film is 26.03μm.

[0052] Example 2

[0053] This embodiment provides a flexible two-dimensional electrode preparation technology based on an ultrathin parylene substrate, which specifically includes the following steps:

[0054] Step 1: Clean the ITO substrate coated with an indium tin oxide conductive layer, and ultrasonically wash it with detergent, deionized water, acetone, and anhydrous ethanol for 15 minutes each. Finally, store the cleaned substrate for later use; prepare a MXene precursor dispersion with a concentration of 5 mg / mL (preparation method is the same as Example 1), and shake the solution before use.

[0055] Step 2: Place the two pretreated ITO substrates in the electrodeposition container with the conductive surfaces facing each other, and fix the two ITO flexible substrates with conductive clamps. Add the prepared MXene precursor dispersion and apply a specific 6V. After the electrodeposition process lasts for 2 minutes, an ITO substrate with a surface-loaded MXene film is obtained. The obtained MXene film is peeled off with the help of a tool, and the surface morphology of the MXene film is observed by atomic force microscopy (AFM) at 25°C and 30% humidity. The experimental results are shown in Figure 8 .

[0056] Step 3: Place the ITO substrate with the MXene film loaded on the surface obtained in step 2 in a parylene CVD device, and use 6g of parylene C powder to deposit the parylene film. The deposition rate is controlled at 0.5μm / h to obtain a composite structure in which the MXene film surface is fully covered with the parylene film. After the encapsulation is completed, one end of the composite structure is selected and an incision is made using laser cutting. Then, the composite film of the parylene / MXene film close to the side of the ITO flexible substrate is peeled off from the incision together. Finally, a flexible two-dimensional electrode composed of a MXene film and a parylene film layer is obtained. In this embodiment, the thickness of the MXene film is 5μm, the thickness of the parylene film is 4.55μm, and the thickness of the composite film is 9.55μm.

[0057] Example 3

[0058] This embodiment provides a flexible two-dimensional electrode preparation technology based on an ultrathin parylene substrate, which specifically includes the following steps:

[0059] Step 1: Clean the ITO substrate coated with an indium tin oxide conductive layer, and ultrasonically wash it with detergent, deionized water, acetone, and anhydrous ethanol for 15 minutes each. Finally, store the washed substrate for later use; prepare a MXene precursor dispersion with a concentration of 5 mg / mL (the same preparation method as in Example 1), and shake the solution before use.

[0060] Step 2: Place the two pretreated substrates in an electrodeposition container with the conductive surfaces facing each other. Add the prepared MXene solution and apply a specific 7V. The electrodeposition process lasts for 2 minutes to obtain an ITO flexible substrate with a surface-loaded MXene film. The obtained MXene film is peeled off with the help of a tool, and the surface morphology of the MXene film is observed by atomic force microscopy (AFM) at 25°C and 30% humidity. The experimental results are shown in Figure 8 .

[0061] Step 3: Place the ITO substrate with the MXene film loaded on the surface obtained in step 2 in a parylene CVD device, and use 7g of parylene C powder to deposit the parylene film. The deposition rate is controlled at 0.5μm / h to obtain a composite structure in which the surface of the MXene film is fully covered with the parylene film. After the encapsulation is completed, an incision is cut at one end of the composite structure using laser cutting, and then the composite film of the parylene / MXene film close to the side of the ITO flexible substrate is peeled off from the incision together. Finally, a flexible two-dimensional electrode composed of a MXene film layer and a parylene film layer is obtained. In this embodiment, the thickness of the MXene film is 16μm, the thickness of the parylene film is 5.33μm, and the thickness of the composite film is 21.33μm.

[0062] Example 4

[0063] This embodiment provides a flexible two-dimensional electrode preparation technology based on an ultrathin parylene substrate, which specifically includes the following steps:

[0064] Step 1: Clean the ITO substrate coated with an indium tin oxide conductive layer, and ultrasonically wash it with detergent, deionized water, acetone, and anhydrous ethanol for 15 minutes each. Finally, store the washed substrate for later use; prepare a MXene precursor dispersion with a concentration of 5 mg / mL (the same preparation method as in Example 1), and shake the solution before use.

[0065] Step 2: Place the two pretreated ITO substrates in the electrodeposition container with the conductive surfaces facing each other, and fix the two ITO substrates with conductive clamps. Add the prepared MXene precursor dispersion and apply a specific 9V. The electrodeposition process lasts for 2 minutes to obtain an ITO flexible substrate with a surface-loaded MXene film. The obtained MXene film is peeled off with the help of a tool, and the surface morphology of the MXene film is observed by atomic force microscopy (AFM) at 25°C and 30% humidity. The experimental results are shown in Figure 8 .

[0066] Step 3: Place the ITO flexible substrate with the MXene film loaded on the surface obtained in step 2 in a parylene CVD device, and use 9g of parylene C powder to deposit the parylene film. The deposition rate is controlled at 0.5μm / h to obtain a composite structure in which the surface of the MXene film is fully covered with the parylene film. After the encapsulation is completed, an incision is cut at one end of the composite structure using laser cutting, and then the composite film of the parylene / MXene film close to the side of the ITO flexible substrate is peeled off from the incision together. Finally, a flexible two-dimensional electrode composite of MXene film and parylene film is obtained. In this embodiment, the thickness of the MXene film is 22μm, the thickness of the parylene film is 6.83μm, and the thickness of the composite film is 28.83μm.

[0067] Example 5

[0068] This embodiment provides a flexible two-dimensional electrode preparation technology based on an ultrathin parylene substrate, which specifically includes the following steps:

[0069] Step 1: Clean the ITO flexible substrate coated with an indium tin oxide conductive layer, and ultrasonically wash it with detergent, deionized water, acetone, and anhydrous ethanol for 15 minutes each. Finally, store the washed substrate for later use; prepare a MXene precursor dispersion with a concentration of 5 mg / mL (preparation method is the same as Example 1), and shake the solution before use.

[0070] Step 2: Place the two pretreated ITO substrates in an electrodeposition container with the conductive surfaces facing each other. Add the prepared MXene precursor dispersion and apply a specific 10V. The electrodeposition process lasts for 2 minutes to obtain an ITO flexible substrate with a surface-loaded MXene film. The obtained MXene film is peeled off with the help of a tool, and the surface morphology of the MXene film is observed by atomic force microscopy (AFM) at 25°C and 30% humidity. The experimental results are shown in Figure 8 .

[0071] Step 3: Place the ITO flexible substrate with the MXene film loaded on the surface obtained in step 2 in a parylene CVD device, and use 10g of parylene C powder to deposit the parylene film. The deposition rate is controlled at 0.5μm / h to obtain a composite structure in which the surface of the MXene film is fully covered with the parylene film. After the encapsulation is completed, an incision is cut at one end of the composite structure using laser cutting, and then the composite film of the parylene / MXene film close to the side of the ITO flexible substrate is peeled off from the incision together. Finally, a flexible two-dimensional electrode composite of MXene film and parylene film is obtained. In this embodiment, the thickness of the MXene film is 23μm, the thickness of the parylene film is 7.51μm, and the thickness of the composite film is 30.51μm.

[0072] Comparative Example 1

[0073] This comparative example provides a method for preparing a MXene film, which is specifically as follows:

[0074] Similar to Example 1, the difference is that the step of preparing the parylene film layer in step 3 is omitted.

[0075] Comparative Example 2

[0076] Similar to Example 1, the difference is that the addition of the surfactant in step 1 is missing.

[0077] Performance Testing

[0078] 1. Acid-base stability test

[0079] The flexible two-dimensional electrodes composed of MXene film layers and parylene film layers prepared in Examples 1-5 were placed in 5wt% HCl and 5wt% NaOH solutions, respectively, and the average roughness Ra of the samples after immersion for 24 hours was observed. Average roughness Ra refers to the arithmetic mean of the absolute value of the surface profile deviation within the sampling length. The value of Ra can reflect the smoothness of the surface and affect the wear resistance, sealing performance and wettability of the coating. The smaller the Ra, the smoother the surface. The experimental results are shown in Figure 9and Table 1. The figure shows that the average roughness of the parylene film on the surface of the original sample (unsoaked) and the sample after 24 hours of immersion in acid and alkali solutions is generally similar, further verifying the acid and alkali resistance of the parylene film. Combined with the observations of the soaked samples, it can be concluded that the composite film prepared in Example 5 has excellent chemical properties and can be effectively used in corrosion protection environments. However, the unencapsulated film will develop bubbles on the edges and surface after immersion for a period of time, and some loss of conductive components will occur.

[0080] Figure 9 Shown from left to right are surface morphology images of samples unsoaked, soaked in 5% HCl solution, and soaked in 5% NaOH solution. The top image is a planar height map of the parylene film, and the bottom image is its corresponding three-dimensional image. The parylene film is uniformly deposited, and the surface morphology of the selected 5μm sample remains virtually unchanged after immersion in the acid and alkali solutions. These results demonstrate that the flexible two-dimensional electrode based on the ultrathin parylene substrate of the present invention exhibits excellent stability and corrosion resistance. Therefore, the fabrication technology provided by the present invention has promising application prospects in the field of electrode preparation.

[0081] Table 1

[0082]

[0083] 2. Antioxidant test

[0084] After further annealing of the parylene film at 100°C for 1 hour, the encapsulated parylene / Mxene / ITO / parylene exhibited stable conductor properties. However, the unencapsulated Mxene / ITO exhibited semiconductor properties after oxidation, indicating that the oxidation results at high temperature ( Figure 10 ).

[0085] 3. Flexible testing

[0086] The present invention makes the ultra-thin flexible two-dimensional electrode obtained in Example 1 into Figure 6 The experiment shown in the figure repeated the bending test of more than 90 degrees. After bending 10 times, the film still existed stably, and there was no obvious falling off or deformation of the film, showing stable bending resistance.

[0087] 4. Flexible memristor performance test

[0088] The memristor based on the ultra-thin flexible two-dimensional electrode obtained in Example 1 was fabricated into a top-bottom structure. The resistive switching behavior of the device was recorded during the forward scan (0V→30V, scanned once every 1V) and reverse scan (reset voltage), showing obvious resistive switching characteristics. The bipolar switching characteristics and multi-conductance state control capability were analyzed ( Figure 11 ).

[0089] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing a flexible two-dimensional electrode based on an ultrathin parylene substrate, characterized in that: The following steps are involved: MXene precursor dispersion was prepared using surfactant and Ti3C2: The MXene precursor dispersion is electroplated to form a MXene film on the surface of the ITO flexible substrate: A parylene coating material is uniformly deposited on the surface of the MXene film to form a parylene film layer, which completely wraps the flexible substrate with the MXene film on its surface, forming a composite structure of parylene / MXene / ITO / parylene film, thereby achieving the encapsulation of the flexible two-dimensional electrode; An incision is made at one end of the composite structure using laser cutting, and then the composite film of the parylene / MXene film close to the side of the ITO flexible substrate is peeled off from the incision together, finally obtaining the flexible two-dimensional electrode based on the ultra-thin parylene substrate.

2. The preparation method according to claim 1, characterized in that The concentration of the MXene precursor dispersion is 5-20 mg / mL; The surfactant includes tetrabutylammonium hexafluorophosphate.

3. The preparation method according to claim 1, characterized in that The ITO flexible substrate is pretreated, and the pretreatment includes the following steps: using detergent, deionized water, acetone, and ethanol for ultrasonic cleaning for at least 15 minutes each to clean it, and then blowing it dry with a nitrogen gun.

4. The preparation method according to claim 1, characterized in that The voltage of the electrodeposition method is set to 5-20V and the time is 2-30 minutes.

5. The preparation method according to claim 1, characterized in that The parylene coating material includes one or more of parylene C powder, parylene N powder, parylene D powder, parylene F powder, and parylene HT powder. The loading amount of the parylene coating material is 0.1-1 g / cm 2 .

6. The preparation method according to claim 1, characterized in that The instrument process parameters used in the process of uniformly depositing the parylene material layer on the surface of the MXene film are as follows: the temperature is gradually increased from 80°C to 110°C, and the temperature is increased in stages, specifically: 80-94°C stage, each temperature increase of 2°C is maintained for 10-20 minutes; 94-110°C stage, each temperature increase of 2°C is maintained for 10 minutes-20.

7. The preparation method according to claim 1, characterized in that The deposition rate of Parylene coating material is 0.5-1μm / h.

8. A flexible two-dimensional electrode based on an ultrathin parylene substrate, characterized in that: The flexible two-dimensional electrode is prepared by the preparation method according to any one of claims 1 to 7, wherein the flexible two-dimensional electrode has a parylene film as a substrate, and a MXene film is provided on the surface of the substrate.

9. The flexible two-dimensional electrode based on an ultrathin parylene substrate according to claim 8, characterized in that: The thickness of the parylene film is 4-8 μm; the thickness of the MXene film is 5-25 μm; and the total thickness of the flexible two-dimensional electrode is 9-33 μm.

10. A flexible electronic device, characterized in that: Comprising the flexible two-dimensional electrode according to claim 8 or 9.

Images