Preparation method of high-performance flexible electronic material film

Abstract

The invention relates to the technical field of thin films, and discloses a preparation method of a high-performance flexible electronic material thin film. The invention discloses a quantum dot / polyaniline composite material, which is prepared from the following components in percentage by weight: 10 to 25 percent of topological insulator nanosheets, 6 to 10 percent of quantum dots, 6 to 10 percent of polyaniline, 6 to 10 percent of metal nano networks, 1 to 3 percent of dithioformamide, 5 to 10 percent of dimethyl sulfoxide, 1 to 3 percent of sodium dodecyl benzene sulfonate and 50 percent of polyethylene glycol terephthalate. By adopting the technical scheme that the topological insulator nanosheets and the conductive polymer cooperatively construct the electron transport network, the technical effects of remarkably reducing the sheet resistance and improving the electron mobility are achieved. Compared with a scheme purely depending on a polymer conductive network in the prior art, the topological insulator nanosheet forms a stable surface conductive channel in the thin film, carrier scattering is reduced, charge transmission efficiency is improved, and the problems that a traditional flexible electronic thin film is uneven in conductivity and limited in electron migration are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of thin films, and specifically to a method for preparing a high-performance flexible electronic material thin film. Background Art

[0002] Flexible electronic material thin films are widely used in fields such as wearable devices, flexible displays, sensors, etc., and have relatively high requirements for their electrical conductivity, mechanical durability, photoelectric conversion efficiency, and environmental stability. However, there are still certain limitations in the existing technologies, which affect the application performance of flexible electronic materials.

[0003] Existing flexible electronic thin films mainly rely on conductive polymers or metal nanonetworks to provide electrical conductivity. However, the carrier mobility of conductive polymers is relatively low, and the electron transport path is easily affected by interface scattering, resulting in limited overall electrical conductivity. And metal nanonetworks usually have relatively high contact resistance, causing energy loss during electron transport and limiting the electron migration ability of the thin film.

[0004] In terms of mechanical stability, existing flexible thin films usually use carbon nanotubes or metal particle conductive networks. However, carbon nanotubes are prone to slip during bending, resulting in the fracture of the conduction path. And due to the discrete distribution of metal particles, they are prone to failure under high strain conditions, making the mechanical durability of the thin film insufficient and difficult to meet the requirements of long-term use.

[0005] In addition, the environmental stability of flexible electronic materials is relatively low. High temperature, high humidity, and acid-base environments are likely to cause the degradation of the conductive network, and the traditional static cross-linked structure lacks the ability to repair, resulting in a short service life of the thin film in harsh environments. Therefore, improving the stability of the conductive network, optimizing the optoelectronic performance, enhancing the mechanical durability, and introducing a dynamic cross-linked structure are the keys to improving the performance of flexible electronic materials. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technologies, the present invention provides a method for preparing a high-performance flexible electronic material thin film, which solves the problems of low electrical conductivity, insufficient photoelectric conversion efficiency, poor mechanical durability, and low environmental stability of existing flexible electronic thin films.

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions: A high-performance flexible electronic material thin film, by mass percentage, includes the following components;

[0008] 10-25% of topological insulator nanosheets, 6-10% of quantum dots, 6-10% of polyaniline, 6-10% of metal nanonetworks, 1-3% of dithiocarbamate, 5-10% of dimethyl sulfoxide, 1-3% of sodium dodecylbenzenesulfonate, and 50% of polyethylene terephthalate.

[0009] Mechanism analysis: Sodium dodecylbenzenesulfonate serves as a flexible substrate, providing substrate support. At the same time, its excellent flexibility and strong mechanical strength ensure the stability of the material film, providing the required flexibility during the film processing and having good compatibility.

[0010] Preferably, the topological insulator nanosheet is bismuth selenide, and its size is 50 - 200 nm.

[0011] Mechanism analysis: Bismuth selenide has surface conductive properties while being an insulator inside, and can form a two-dimensional conductive channel for surface electron flow. This property helps the stable conductivity of the electronic material film on the flexible substrate.

[0012] Preferably, the quantum dots are cadmium selenide quantum dots, and their particle size is 5 - 10 nm.

[0013] Mechanism analysis: Cadmium selenide quantum dots can provide additional electron states, increase the carrier density of the material, and enhance the electron conductivity of the film.

[0014] Preferably, the metal nanonetwork includes silver nanowires, where the length of the metal nanowires is 1 - 20 μm and the diameter is 10 - 50 nm.

[0015] Mechanism analysis: Silver nanowires form a network structure in the film, providing an additional conduction path through the electron transfer between the metal nanowires.

[0016] Preparation method of high-performance flexible electronic material film, including the following steps;

[0017] S1. Use polyethylene terephthalate as a flexible substrate with a thickness of 10 - 200 μm, clean it with deionized water and dry it for standby;

[0018] S2. Mix dimethyl sulfoxide and deionized water, stir for 30 - 60 min, then add sodium dodecylbenzenesulfonate and stir for 30 - 60 min. After mixing, add polyaniline and stir for 60 - 120 min to obtain a conductive polymer solution;

[0019] S3. Use the spin coating method to deposit the conductive polymer solution on the flexible substrate to form a conductive matrix layer;

[0020] S4. Use the solvothermal exfoliation method to ultrasonically exfoliate the topological insulator material in N-methylpyrrolidone solvent for 6 - 12 h, centrifuge at 5000 - 10000 rpm, collect the topological insulator nanosheets, and coat the surface of the conductive matrix layer by electrostatic spraying method;

[0021] S5. Prepare quantum dots by solvothermal method, react at 180 - 250 °C for 3 - 6 h, centrifuge at 6000 - 12000 rpm, and modify on the surface of topological insulator nanosheets by electrostatic self-assembly method;

[0022] S6. Spray metal nanowires on the surface of quantum dots by spraying method to form a metal nanowire layer;

[0023] S7. Use dithiocarbamide as a dynamic cross-linking agent and spin-coat it evenly on the surface of the metal nanowire layer, stir at room temperature for 1 - 3 h to complete cross-linking to form a flexible electronic material thin film.

[0024] Preferably, the mixing ratio of dimethyl sulfoxide to deionized water in step S2 is 1:2 - 1:10.

[0025] Preferably, the spin-coating speed in step S3 is 500 - 2000 rpm, the spin-coating time is 30 - 60 s, the baking temperature is 100 - 180 °C, and the baking time is 10 - 30 min.

[0026] Preferably, the concentration of N-methylpyrrolidone used in the solvothermal exfoliation method in step S4 is 0.5 - 2 M.

[0027] Preferably, the spraying pressure of the electrostatic spraying method in step S4 is 50 - 100 kPa, and the number of spraying times is 5 - 8 times.

[0028] Preferably, the spraying pressure in step S6 is 50 - 150 kPa, the number of spraying times is 3 - 10 times, the drying temperature is 60 - 120 °C, and the drying time is 30 - 90 min.

[0029] The present invention provides a method for preparing a high-performance flexible electronic material thin film. It has the following beneficial effects:

[0030] 1. By adopting the technical solution of synergistically constructing an electron transport network with topological insulator nanosheets and conductive polymers, the present invention achieves the technical effects of significantly reducing the sheet resistance and improving the electron mobility. Compared with the existing technology that simply relies on the polymer conductive network, the topological insulator nanosheets form stable surface conductive channels in the thin film, reduce carrier scattering, improve the charge transport efficiency, and solve the problems of uneven conductivity and limited electron migration in traditional flexible electronic thin films.

[0031] 2. Through the combined application of cadmium selenide quantum dots and topological insulators, the present invention achieves the technical effects of enhancing the light absorption ability and improving the separation efficiency of photo-generated carriers. Compared with the prior art solutions using traditional oxide quantum dots, cadmium selenide quantum dots have a higher external quantum efficiency in the visible light band and a good interface match with topological insulators, resulting in a faster photocurrent response and avoiding the decrease in conversion efficiency caused by the low electron injection ability and high recombination rate of quantum dots in the existing solutions.

[0032] 3. By using silver nanowires to construct a flexible metal network and optimizing the interface connection, the present invention improves the mechanical durability of the thin film and achieves the technical effect of maintaining a low sheet resistance under high bending and high stretching conditions. The prior art usually uses carbon nanotubes or low-efficiency metal particle networks, which are prone to breakage during the deformation process due to their high structural discreteness, damaging the conductive network. The continuous metal nanowire interwoven structure of the present invention solves the problem of insufficient stability of the thin film conductive network under high strain.

[0033] 4. By introducing a dynamic cross-linking agent to establish a reversible bonding network, the present invention achieves the technical effect of enhancing the long-term environmental stability and chemical corrosion resistance of the thin film. Traditional flexible electronic thin films are prone to irreversible degradation under high temperature, high humidity or acid-base environments, resulting in rapid deterioration of electrical properties. However, the dynamic cross-linking structure adopted by the present invention enables the material to maintain a stable conductive channel under extreme environments, thus effectively solving the problems of insufficient durability and limited service life of thin films in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flowchart of the method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] Please refer to the attached Figure 1 ;

[0037] Example 1

[0038] Steps:

[0039] Select polyethylene terephthalate as the flexible substrate with a thickness of 150 μm, clean it and dry it at 90 °C for 1 h for standby.

[0040] In deionized water, dimethyl sulfoxide (DMSO) was added and stirred for 45 min to form a homogeneous solution. Then sodium dodecylbenzenesulfonate was added and stirring was continued for 30 min to ensure complete dissolution.

[0041] Polyaniline (PANI) was added and stirred for 80 min until the solution was homogeneous, obtaining a conductive polymer solution.

[0042] The conductive polymer solution was coated on a PET substrate using the spin coating method at a spin coating speed of 1300 rpm for 45 s, and then baked at 150 °C for 20 min to form a conductive matrix layer.

[0043] Using the solvothermal exfoliation method, bismuth selenide nanosheets were mixed with N-methylpyrrolidone (NMP) solvent and ultrasonically exfoliated for 8 h. After centrifugation, the topological insulator nanosheets were collected and sprayed onto the conductive matrix layer at a spraying pressure of 70 kPa for 6 times.

[0044] Cadmium selenide quantum dots were prepared by the solvothermal method at 200 °C for 4 h, centrifuged and collected, and the quantum dots were modified onto the surface of the topological insulator nanosheets by electrostatic self-assembly.

[0045] Silver nanowires were sprayed on the surface of the quantum dots using the spraying method at a spraying pressure of 80 kPa for 7 times, with a drying temperature of 100 °C and a drying time of 60 min.

[0046] Finally, dithiocarbamide was uniformly coated as a dynamic crosslinking agent using the spin coating method and stirred at room temperature for 2 h to complete crosslinking, obtaining a high-performance flexible electronic material film.

[0047] Component ratio:

[0048] Polyaniline: 6%

[0049] Dithiocarbamide: 3%

[0050] Dimethyl sulfoxide: 6%

[0051] Sodium dodecylbenzenesulfonate: 3%

[0052] Bismuth selenide (topological insulator nanosheets): 12%

[0053] Cadmium selenide quantum dots: 9%

[0054] Silver nanowires: 10%

[0055] Polyethylene terephthalate (PET): 50%.

[0056] Example 2

[0057] Steps:

[0058] Select a polyethylene terephthalate (PET) substrate with a thickness of 120 μm, clean it and dry for 1 h.

[0059] Mix dimethyl sulfoxide and deionized water, stir for 30 min, add sodium dodecylbenzenesulfonate, and then stir for another 30 min to ensure complete dissolution.

[0060] Add polyaniline to the solution and continue stirring for 90 min to form a homogeneous conductive polymer solution.

[0061] Coat the conductive polymer solution on the PET substrate using the spin coating method at a spin speed of 1500 rpm for 40 s, and then bake at 140 °C for 25 min to form a conductive matrix layer.

[0062] Ultrasonically exfoliate bismuth selenide nanosheets in N-methylpyrrolidone for 7 h, centrifuge and collect the nanosheets. Coat the nanosheets onto the conductive matrix layer by electrostatic spraying at a spraying pressure of 60 kPa and 8 spraying times.

[0063] Prepare quantum dots (cadmium selenide quantum dots) by solvothermal reaction at 220 °C for 5 h, centrifuge and collect the quantum dots, and decorate them onto the surface of topological insulator nanosheets by electrostatic self-assembly.

[0064] Spray silver nanowires on the surface of the quantum dots by spraying method at a spraying pressure of 100 kPa, 6 spraying times, a drying temperature of 95 °C, and a drying time of 55 min.

[0065] Use the spin coating method to coat dithiocarbamate on the surface of the metal nanowire layer, and complete cross-linking by stirring at room temperature for 2 h to finally form a high-performance flexible electronic material film.

[0066] Component ratio:

[0067] Polyaniline: 8%

[0068] Dithiocarbamate: 2%

[0069] Dimethyl sulfoxide: 7%

[0070] Sodium dodecylbenzenesulfonate: 3%

[0071] Bismuth selenide (topological insulator nanosheets): 15%

[0072] Cadmium selenide quantum dots: 7%

[0073] Silver nanowires: 8%

[0074] Polyethylene terephthalate (PET): 50%.

[0075] Example 3

[0076] Steps:

[0077] Select a polyethylene terephthalate (PET) substrate with a thickness of 100 μm, clean it, and dry it at 80 °C for 30 min.

[0078] Mix dimethyl sulfoxide (DMSO) with deionized water, stir for 40 min, add sodium dodecylbenzenesulfonate, and continue stirring for 35 min until the solution is homogeneous.

[0079] Add polyaniline (PANI) and stir for 70 min until the solution is completely dissolved.

[0080] Use the spin coating method to coat the conductive polymer solution on the polyethylene terephthalate substrate at a spin coating speed of 1400 rpm for 30 s, and then bake it at 160 °C for 20 min.

[0081] Adopt the solvothermal method, mix bismuth selenide with N-methylpyrrolidone solution, and ultrasonically exfoliate for 6 h. Centrifuge and separate to collect the topological insulator nanosheets, and use the electrostatic spraying method to coat them on the surface of the conductive matrix layer with a spraying pressure of 75 kPa and 5 spraying times.

[0082] React at 230 °C for 4 h to prepare quantum dots (cadmium selenide quantum dots), centrifuge and separate to collect the quantum dots. Modify them on the surface of the topological insulator nanosheets by electrostatic self-assembly.

[0083] Use the spraying method to spray silver nanowires on the surface of the quantum dots with a spraying pressure of 85 kPa, 7 spraying times, a drying temperature of 110 °C, and a drying time of 50 min.

[0084] Use the spin coating method to uniformly coat dithiocarbamide on the surface of the metal nanowire layer, stir at room temperature for 2 h to complete crosslinking, and obtain the final flexible electronic material film.

[0085] Comparative Example 1 (lacking topological insulator nanosheets)

[0086] Design basis:

[0087] The topological insulator nanosheets provide an efficient surface electron transport path in the present invention. In this comparative example, by removing the topological insulator nanosheets, the effects on the conductivity and stability of the film are investigated.

[0088] Preparation process:

[0089] Select a polyethylene terephthalate (PET) substrate with a thickness of 150 μm, clean it and dry it for standby.

[0090] Prepare a conductive polymer solution: dimethyl sulfoxide (7%) + sodium dodecylbenzenesulfonate (3%) + polyaniline (6%). After stirring and dissolving, it is used for spin coating. The spin coating speed is 1300 rpm, the spin coating time is 45 s, and it is baked at 150 °C for 20 min.

[0091] Without adding topological insulator nanosheets, directly proceed to the subsequent steps.

[0092] Synthesize cadmium selenide quantum dots (9%) by solvothermal method. After centrifugal separation, they are modified on the surface of the conductive layer.

[0093] Deposit silver nanowires (10%) by spraying method. The spraying pressure is 80 kPa, and the spraying times are 6 times.

[0094] Spin coat dithiocarbamate (3%) as a dynamic crosslinking agent and stir at room temperature for 2 h to finally form a flexible electronic material film.

[0095] Difference:

[0096] This comparative example does not contain topological insulator nanosheets, and the remaining steps are the same as those in Example 1.

[0097] Comparative Example 2 (using traditional oxide semiconductor quantum dots for quantum dots)

[0098] Design basis:

[0099] This invention uses cadmium selenide quantum dots to enhance the electron transport ability, while this comparative example uses traditional oxide semiconductor quantum dots (such as titanium dioxide TiO 2 quantum dots) to investigate their effects on the film properties.

[0100] Preparation process:

[0101] Use the same PET substrate (50%) as in Example 2, and a conductive polymer solution (DMSO 7%, sodium dodecylbenzenesulfonate 3%, polyaniline 8%). After spin coating, bake to form a film.

[0102] Prepare topological insulator nanosheets (15%) by solvothermal exfoliation method and spray them onto the conductive layer.

[0103] Replace cadmium selenide quantum dots with titanium dioxide (TiO 2 ) quantum dots (7%), and use the same other modification methods.

[0104] Deposit silver nanowires (8%) by spraying method. The spraying pressure is 80 kPa, and the spraying times are 6 times.

[0105] Spin coat dithiocarbamate (2%) as a dynamic crosslinking agent and stir at room temperature for 2 h to finally form a film.

[0106] Difference:

[0107] In this comparative example, cadmium selenide quantum dots are replaced by titanium dioxide quantum dots.

[0108] Comparative Example 3 (Metal nanonetwork replaced by conventional carbon nanotubes)

[0109] Design basis:

[0110] This invention uses silver nanowires as the metal nanonetwork, and this comparative example uses conventional carbon nanotubes (CNT S ) to replace the silver nanowires to investigate the influence of the metal nanonetwork on the film conductivity and structural stability.

[0111] Preparation process:

[0112] Use the same PET substrate (50%) as in Example 3, the conductive polymer solution (DMSO 6%, sodium dodecylbenzenesulfonate 2%, polyaniline 10%), spin-coat and then bake to form a film.

[0113] Prepare topological insulator nanosheets (15%) by solvothermal exfoliation method and spray them onto the conductive layer.

[0114] Prepare cadmium selenide quantum dots (8%) by solvothermal method, and modify them on the surface of topological insulator nanosheets after centrifugal separation.

[0115] Replace the silver nanowires with carbon nanotubes (7%), the spraying process is the same, the spraying pressure is 90 kPa, and the spraying times are 6 times.

[0116] Spin-coat dithiocarbamide (2%) as a dynamic crosslinking agent and stir at room temperature for 2 h to finally form a film.

[0117] Difference:

[0118] In this comparative example, the silver nanowires are replaced by carbon nanotubes (CNTs).

[0119] Experiment 1: Influence of topological insulator nanosheets on film conductivity

[0120] Experiment description

[0121] Experiment purpose

[0122] The purpose of this experiment is to explore the role of topological insulator nanosheets (bismuth selenide) in flexible electronic material films, especially their influence on the conductive performance. Topological insulator materials form high-mobility electron transport channels on the surface, which may have a significant impact on the overall electrical properties of the film.

[0123] Comparative Example 4 (Removing the dynamic crosslinking agent)

[0124] Design basis:

[0125] Dynamic crosslinking agents (such as dithiocarbamates) can enhance the mechanical stability of the film. In this comparative example, the dynamic crosslinking agent was removed to investigate its effect on the structural stability.

[0126] Preparation process:

[0127] The same PET substrate (50%) as in Example 2 was used, and the conductive polymer solution (7% DMSO, 3% sodium dodecylbenzenesulfonate, 8% polyaniline) was spin-coated and baked into a film.

[0128] Topological insulator nanosheets (15%) were prepared by solvothermal exfoliation and sprayed onto the conductive layer.

[0129] Cadmium selenide quantum dots (7%) were prepared using the solvothermal method, and after centrifugal separation, they were modified onto the surface of the topological insulator nanosheets.

[0130] Silver nanowires (8%) were deposited by spraying, with a spraying pressure of 80 kPa and 6 spraying times.

[0131] Dithiocarbamate was not added, and the remaining steps were the same.

[0132] Difference:

[0133] In this comparative example, the dynamic crosslinking agent was not used, and the remaining processes were the same as in Example 2.

[0134] Experimental object

[0135] Example 1 (containing bismuth selenide topological insulator nanosheets)

[0136] Comparative Example 1 (without bismuth selenide topological insulator nanosheets)

[0137] Experimental steps

[0138] Sample preparation

[0139] Flexible electronic films were prepared according to the processes of Example 1 and Comparative Example 1, with 5 samples in each group.

[0140] The sample size was uniformly cut into 2 cm × 2 cm to ensure test consistency.

[0141] Sheet resistance measurement;

[0142] Using a four-probe tester (Keithley 2400 + probe station), the sheet resistance of the samples was measured.

[0143] Test environment: temperature 25°C, humidity 50% RH, to avoid environmental factor interference.

[0144] For each sample, 5 measurement points were randomly selected and the average value was taken to reduce local errors.

[0145] Electron mobility measurement;

[0146] Non-contact Hall detection was carried out using a Hall effect tester (LakeShore 7707A) to measure the electron mobility (cm 2 / V·s).

[0147] The magnetic field strength was set to 0.5 T, the measurement temperature was 298 K, and the current source was 1 mA.

[0148] Record the Hall voltage and calculate the electron mobility.

[0149] Data sorting and comparative analysis;

[0150] Statistical data and analyze the influence of topological insulator nanosheets on the electrical properties of the thin film.

[0151] Plot the data distribution and observe the conductivity uniformity and stability of the samples.

[0152] Experimental data table

[0153] Table 1: Test data of sheet resistance and electron mobility of Example 1 and Comparative Example 1.

[0154] Sample Number Sheet Resistance (Ω·m) <![CDATA[Electron mobility (cm 2 / V·s)]]> Example 1 315.6 12.3 Example 1 298.2 13.1 Example 1 322.8 11.9 Example 1 309.4 12.7 Example 1 301.1 12.5 Comparative Example 1 725.3 5.6 Comparative Example 1 711.8 6.2 Comparative Example 1 738.4 5.2 Comparative Example 1 699.9 6.0 Comparative Example 1 715.7 5.8

[0155] The introduction of topological insulator nanosheets has significantly changed the electron transport characteristics of the thin film. The establishment of surface conduction paths enables electrons to no longer be restricted by the local polyaniline conductive network but move rapidly along the interface of the nanosheets. This high-mobility electron transport mode significantly reduces the sheet resistance and greatly improves the electron mobility. In contrast, for the thin film without topological insulator, the conductivity depends on the contact between polyaniline and silver nanowires, and the electron transport is more restricted, showing a higher sheet resistance and a lower electron mobility.

[0156] The presence of bismuth selenide not only enhances the conductivity of the thin film but also improves the electron transport mode. Hall effect measurements show that the average carrier mobility in Example 1 is 12 cm 2 / V·s, while that in Comparative Example 1 is only 5 - 6 cm 2 / V·s. This indicates that in the thin film containing topological insulator, the scattering of electrons inside the material is reduced and the migration ability is stronger. On the other hand, in Comparative Example 1, due to the lack of topological insulator, the movement of carriers is restricted by the irregular structure of the interface between polyaniline and silver nanowires, resulting in a decrease in transport efficiency.

[0157] The results clearly demonstrate the contribution of topological insulators. Electrons flow along the surface of the nanosheets rather than relying on hopping transport across multiple conductive regions. In traditional conductive thin films, significant resistance fluctuations often occur due to structural inhomogeneities. However, in this invention, by introducing topological insulator nanosheets, a stable and efficient electron transport path is achieved, making the electrical properties of the thin film more controllable and uniform.

[0158] Experiment 2: Influence of Quantum Dot Type on Photovoltaic Conversion Efficiency

[0159] Experiment Description

[0160] Experiment Purpose

[0161] This experiment aims to explore the influence of quantum dot types on the optoelectronic properties of flexible electronic thin films, particularly the differences in photovoltaic conversion capabilities between cadmium selenide (CdSe) quantum dots and titanium dioxide (TiO 2 ) quantum dots. As semiconductor materials with tunable band structures, quantum dots can absorb light energy and convert it into electron-hole pairs. Different types of quantum dots exhibit differences in carrier separation and transport efficiency. Therefore, this experiment compares two quantum dot materials and analyzes their different performances in photovoltaic conversion efficiency.

[0162] Experiment Object

[0163] Example 2 (using cadmium selenide quantum dots)

[0164] Comparative Example 2 (using titanium dioxide quantum dots)

[0165] Experiment Steps

[0166] Sample Preparation

[0167] Prepare flexible electronic thin films according to the processes of Example 2 and Comparative Example 2, with 5 samples in each group to ensure the repeatability of the experiment.

[0168] Cut the sample size to 1 cm × 1 cm to ensure uniform illumination.

[0169] Photocurrent Response Test

[0170] Use a photocurrent measurement system (Newport2931-C) for testing.

[0171] Light Source: AM1.5G simulated sunlight with an intensity of 100 mW / cm 2 , ensuring uniform experimental conditions.

[0172] Record the photocurrent of the sample under a bias voltage of 0.1 V.

[0173] Sampling time: 0 - 10 s, sampling 10 groups of data per second to observe the light response rate and stability.

[0174] External Quantum Efficiency (EQE) Test

[0175] The light absorption ability of the quantum dots was tested using an Ori el QE-R spectral response system.

[0176] The wavelength was scanned in the range of 300 - 800 nm with a wavelength step of 10 nm, and the EQE values at different wavelengths were recorded.

[0177] The average EQE of the sample in the visible light band (400 - 700 nm) was calculated.

[0178] Experimental Data Table

[0179] Table 2: Photocurrent and external quantum efficiency (EQE) test data of Example 2 and Comparative Example 2.

[0180] Sample Number <![CDATA[Photocurrent density (mA / cm 2 )]]> EQE (%) (400 - 700nm) Example 2 1.21 62.8 Example 2 1.34 65.2 Example 2 1.28 63.7 Example 2 1.19 60.9 Example 2 1.30 64.1 Comparative Example 2 0.57 41.3 Comparative Example 2 0.64 45.2 Comparative Example 2 0.61 43.6 Comparative Example 2 0.55 40.8 Comparative Example 2 0.59 42.9

[0181] Different selections of quantum dots directly affect the magnitude of the photocurrent and the carrier transport efficiency. Cadmium selenide quantum dots have a stronger light absorption ability in the visible light range due to their moderate bandgap, and their surface state regulation is relatively mature, providing a stable electron-hole separation channel. Compared with titanium dioxide quantum dots, their photogenerated carrier recombination rate is lower, so under the same light intensity, the photocurrent density of cadmium selenide quantum dots is generally more than twice as high. Titanium dioxide quantum dots have strong absorption in the ultraviolet region due to their wide bandgap, but weak response in the visible light region, resulting in a low overall photocurrent.

[0182] The comparison of the external quantum efficiency (EQE) can better reflect the essential differences between materials. The EQE of the cadmium selenide quantum dot sample remains above 60% in the range of 400 - 700 nm, indicating a high quantum conversion efficiency in the visible light band. For the titanium dioxide quantum dots used in Comparative Example 2, the EQE is only between 40% and 45%, which is significantly lower. This is related to its high carrier recombination rate and weak electron injection ability. Due to the low electron affinity of titanium dioxide, photo-generated electrons are difficult to effectively enter the conductive polymer layer, resulting in a reduction in its external quantum efficiency.

[0183] The experimental results further verified the role of topological insulator nanosheets. Although quantum dots are mainly responsible for light absorption and electron generation, if the migration of electrons within the thin film is blocked, the final photocurrent will still be limited. The combination of cadmium selenide quantum dots and topological insulator nanosheets optimizes the carrier transport path, enabling electrons to cross the interface more smoothly and improving the photoelectric conversion ability of the entire thin film. In contrast, the low mobility of titanium dioxide quantum dots shows significant carrier losses in the absence of additional electron channels, further reducing the light response performance.

[0184] Experiment 3: Influence of Metal Nanonetwork Type on Mechanical Stability

[0185] Experiment Description

[0186] Experiment Purpose

[0187] This experiment aims to explore the influence of the type of metal nanonetwork on the mechanical stability of flexible electronic material films. Silver nanowires and carbon nanotubes are common conductive network structures, but their roles in flexible films are essentially different. Due to their high conductivity and low contact resistance, silver nanowires can form continuous electron transport paths inside the film, while carbon nanotubes rely on π-π interactions to form a conductive network, but their distribution uniformity is poor. By comparing the two metal networks, their effects on the film properties under extreme conditions such as bending and stretching are analyzed.

[0188] Experiment Object;

[0189] Example 3 (Using Silver Nanowires)

[0190] Comparative Example 3 (Using Carbon Nanotubes)

[0191] Experiment Steps;

[0192] Sample Preparation;

[0193] Flexible films were prepared according to the processes of Example 3 and Comparative Example 3, with 5 samples in each group, cut into a size of 2 cm × 2 cm.

[0194] Bending Durability Test;

[0195] An Instron 5943 bending life tester was used to test the conductive stability of the film under repeated bending.

[0196] The bending radius was set to 5 mm, the bending angle was 180°, the frequency was 2 Hz, and 1000 bending cycles were performed.

[0197] After every 200 bends, a four-probe tester (Keithley 2400) was used to measure the change in sheet resistance.

[0198] Tensile Test;

[0199] A Shimadzu AGS-X electronic universal testing machine was used to test the tensile limit of the film.

[0200] The two ends of the sample were clamped and stretched at a speed of 5 mm / min until fracture, and the stress-strain curve was recorded.

[0201] Calculate the maximum strain (%) and fracture strength (MPa) of the film.

[0202] Experiment Data Table;

[0203] Table 3: Bending durability and tensile test data of Example 3 and Comparative Example 3.

[0204]

[0205] The presence of silver nanowires enables the film to maintain a low sheet resistance during bending. Even after 1000 bending cycles, the stability of the conductive network remains relatively high. In contrast, the network structure of carbon nanotubes is damaged during bending, leading to a sharp increase in sheet resistance and even electrical failure in some areas. The aspect ratio of silver nanowires is much larger than that of carbon nanotubes, allowing for the formation of a more stable intertwined structure. When the film is bent, the contact points between nanowires do not easily break, while the π-π stacking between carbon nanotubes is relatively weak, and interface slippage is likely to occur during bending, resulting in the fracture of local conduction paths.

[0206] The results of the tensile experiment also reflect the different behaviors of metal networks under stress. The silver nanowire network forms continuous electron channels in the film and can maintain conductivity even at high strains. In contrast, carbon nanotubes are difficult to be uniformly stressed during stretching. Once the critical stretch ratio is reached, the connection points are prone to breakage, causing the overall conductive network to fail. Therefore, the maximum strain of the silver nanowire film can reach more than 15%, while the carbon nanotube film can only withstand a deformation of less than 8%.

[0207] The mechanical stability of flexible electronic materials depends not only on the flexibility of the substrate but more crucially on the structural design of the conductive network. Due to its low interface resistance and excellent connection stability, silver nanowires can maintain good conductivity under continuous bending and stretching conditions. In contrast, carbon nanotubes are prone to structural separation under extreme deformation, unable to ensure long-term stability during use. Therefore, in application scenarios that require high bending durability and tensile properties, such as wearable electronic devices, silver nanowires are obviously a more ideal choice.

[0208] Experiment 4: Influence of dynamic crosslinking agents on the structural stability of the film

[0209] Experiment description;

[0210] Experiment purpose;

[0211] This experiment aims to study the influence of dynamic crosslinking agents (such as dithiocarbamate) on the long-term stability of the film. Dynamic crosslinking agents can provide reversible bonding structures, endowing the film with self-healing ability under external stimuli and improving weather resistance. If the dynamic crosslinking agent is removed, the film may be more vulnerable to environmental influences, resulting in a decrease in mechanical strength and chemical stability. Therefore, through accelerated aging experiments and chemical stability tests, this experiment analyzes the performance differences between films with and without dynamic crosslinking agents.

[0212] Experiment object;

[0213] Example 2 (including dithiocarbamate as the dynamic crosslinking agent)

[0214] Comparative Example 4 (without dynamic crosslinking agent)

[0215] Experimental procedures

[0216] Sample preparation

[0217] Prepare films according to the processes of Example 2 and Comparative Example 4 respectively, with 5 samples in each group.

[0218] Uniformly cut the sample size to 2 cm × 2 cm to ensure the comparability of test data.

[0219] Environmental aging test

[0220] Use a Binder KBF720 thermo-hygrostat to conduct an accelerated aging experiment.

[0221] Set the temperature at 85 °C and the humidity at 85% RH to simulate the material degradation process under extreme environments.

[0222] Measure the sheet resistance of the film once every 24 h (four-probe method) for 7 days to observe the change in electrical properties.

[0223] Chemical stability test

[0224] Immerse the samples in different media respectively

[0225] Acidic solution (HCl, pH = 3)

[0226] Alkaline solution (NaOH, pH = 11)

[0227] Deionized water (pH = 7)

[0228] After soaking for 24 h, measure the change in sheet resistance and use a scanning electron microscope (SEM) to observe the change in the surface morphology of the film.

[0229] Experimental data table

[0230] Table 4: Sheet resistance change and chemical stability test data of Example 2 and Comparative Example 4

[0231]

[0232]

[0233] The presence of the dynamic crosslinking agent enables the film to maintain relatively stable electrical properties under high-temperature and high-humidity environments. Even after 7 days of aging test, the change in sheet resistance is less than 6%, while the sheet resistance of the sample without the dynamic crosslinking agent doubles, indicating that its conductive network significantly degrades under environmental influence. The dynamic crosslinking network can reduce the erosion of water molecules on the material interface under high-humidity conditions, lower the degree of discretization at the interface, and thus maintain the overall conductivity of the material. For the film without the dynamic crosslinking agent, its interface undergoes irreversible structural changes under the action of humidity, resulting in the obstruction of the carrier transport channels and ultimately manifested as a sharp increase in sheet resistance.

[0234] The results of the acid-base stability test also demonstrate the role of the dynamic crosslinking agent in chemical protection. After the sample of Example 2 was immersed in solutions with pH = 3 and pH = 11 for 24 h, the change in sheet resistance was within 3.5% in both cases, while the change in sheet resistance of the sample of Comparative Example 4 exceeded 20%. This shows that the dynamic crosslinking network effectively enhances the chemical stability of the film, enabling it to still have good conductive ability in extreme environments. For the film without the dynamic crosslinking agent, due to the lack of flexible reversible bonding inside, the acid-base solution easily damages the film structure, causing damage to the conductive channels and resulting in a significant increase in sheet resistance.

[0235] The role of the dynamic crosslinking agent is not limited to enhancing the mechanical properties of the film in the short term. More importantly, it improves the reliability of its long-term use. Whether it is the high temperature and high humidity of the external environment or the corrosive effect of chemical media, the dynamic crosslinking network provides a mechanism for repair and stabilization, enabling the material structure to be adaptively adjusted and extending the service life of the film. Materials lacking dynamic crosslinking lack the ability to respond to extreme environments and ultimately lead to irreversible degradation. This characteristic makes the flexible electronic materials containing the dynamic crosslinking agent more promising and durable in long-term use environments such as wearable devices and intelligent sensors.

[0236] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. High-performance flexible electronic material film, characterized in that: In terms of mass percentage, it includes the following components; Topological insulator nanosheets 10-25%, quantum dots 6-10%, polyaniline 6-10%, metal nanonetwork 6-10%, dithioformamide 1-3%, dimethyl sulfoxide 5-10%, sodium dodecylbenzene sulfonate 1-3% and polyethylene terephthalate 50%.

2. The high performance flexible electronic material film according to claim 1, characterized in that: The topological insulator nanosheet is bismuth selenide, and its size is 50-200nm.

3. The high performance flexible electronic material film according to claim 1, characterized in that: The quantum dots are cadmium selenide quantum dots, and their particle size is 5-10nm.

4. The high performance flexible electronic material film according to claim 1, characterized in that: The metal nanonetwork comprises silver nanowires, wherein the length of the metal nanowires is 1-20 μm and the diameter is 10-50 nm.

5. A method for preparing a high-performance flexible electronic material film, according to the high-performance flexible electronic material film according to claims 1-4, characterized in that: The steps include: S1, using polyethylene terephthalate as a flexible substrate with a thickness of 10-200 μm, washing with deionized water and drying for later use; S2, mixing dimethyl sulfoxide and deionized water, stirring for 30-60 minutes, adding sodium dodecylbenzene sulfonate and stirring for 30-60 minutes, and after mixing, adding polyaniline and stirring for 60-120 minutes to obtain a conductive polymer solution; S3, depositing a conductive polymer solution on the flexible substrate by spin coating to form a conductive base layer; S4, using a solvent thermal stripping method, ultrasonically stripping the topological insulator material in N-methylpyrrolidone solvent for 6-12 hours, centrifuging at 5000-10000 rpm, collecting the topological insulator nanosheets, and coating the surface of the conductive substrate layer by electrostatic spraying; S5, preparing quantum dots by solvothermal method, reacting at 180-250°C for 3-6h, centrifuging at 6000-12000rpm, and modifying them on the surface of topological insulator nanosheets by electrostatic self-assembly; S6, spraying the metal nanowires onto the surface of the quantum dots by a spraying method to form a metal nanowire layer; S7. Use dithioformamide as a dynamic cross-linking agent and evenly coat it on the surface of the metal nanowire layer by spin coating, and stir at room temperature for 1-3 hours to complete cross-linking to form a flexible electronic material film.

6. The method for preparing a high-performance flexible electronic material film according to claim 5, characterized in that: The mixing ratio of dimethyl sulfoxide to deionized water in step S2 is 1:2-1:

10.

7. The method for preparing a high-performance flexible electronic material film according to claim 5, characterized in that: In step S3, the spin coating speed is 500-2000 rpm, the spin coating time is 30-60 s, the baking temperature is 100-180° C., and the baking time is 10-30 min.

8. The method for preparing a high-performance flexible electronic material film according to claim 5, characterized in that: The concentration of N-methylpyrrolidone used in the solvent thermal stripping method in step S4 is 0.5-2M.

9. The method for preparing a high-performance flexible electronic material film according to claim 5, characterized in that: The spraying pressure of the electrostatic spraying method in step S4 is 50-100 kPa, and the number of spraying times is 5-8 times.

10. The method for preparing a high-performance flexible electronic material film according to claim 5, characterized in that: In step S6, the spraying pressure is 50-150 kPa, the number of spraying times is 3-10 times, the drying temperature is 60-120° C., and the drying time is 30-90 min.

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