Carbon nanotube-two-dimensional perovskite heterojunction cold cathode

Abstract

The invention relates to the technical field of advanced semiconductor electronic devices, and discloses a carbon nanotube-two-dimensional perovskite heterojunction cold cathode which comprises the following raw materials in percentage by weight: 5-15% of carbon nanotubes, 5-15% of two-dimensional perovskite, 5-15% of carbon nanotubes, 5-15% of carbon nanotubes, 5-15% of two-dimensional perovskite, and the balance of water. 20%-30% of a two-dimensional perovskite precursor solution; 10%-20% of silver nanowires; 3%-6% of a polyvinylidene fluoride adhesive; 2%-5% of a conductive polymer binder; 15%-25% of a dispersant; 5%-10% of a buffer layer material; 1%-5% of an antioxidant additive; 3%-8% of a metal bonding layer; 10%-20% of a substrate material; according to the cold cathode, through composite construction of semiconductor type / metal type carbon nanotubes, integration of a silver nanowire three-dimensional network, the synergistic effect of the buffer layer and the interface modification layer and introduction of an anti-oxidation system, the problems that in the prior art, the electron emission efficiency is low, interface compounding is serious, and the material stability is poor are solved; the beneficial effects of remarkably improving the electron emission performance of the cold cathode, enhancing the stability of the device and prolonging the service life are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of advanced semiconductor electronic device technology, and discloses a carbon nanotube-two-dimensional perovskite heterojunction cold cathode. BACKGROUND

[0002] The cold cathode is a core component of the vacuum electronic device, and its performance directly determines the electron emission efficiency, stability and service life of the device. The traditional cold cathode material mainly depends on a metal micro-tip array, a diamond film or a single carbon nanotube system, which has the following inherent defects: first, the metal micro-tip array needs high-precision processing and is easy to be ion bombardment failure; second, the diamond film has good chemical stability but high electron affinity, resulting in high emission threshold voltage; and the single carbon nanotube system has excellent field emission characteristics, but has problems of fragile conductive network, serious interface recombination and insufficient long-term stability. In addition, although the emerging perovskite material exhibits excellent photoelectric properties, its inherent ion migration characteristics and environmental sensitivity seriously restrict its application in vacuum electronic devices. SUMMARY

[0003] (I) Technical problems solved In view of the defects of the prior art, the present application provides a carbon nanotube-two-dimensional perovskite heterojunction cold cathode, which has the advantages of high electron emission efficiency, strong interface stability and excellent mechanical toughness, and solves the problems of low electron emission efficiency, serious interface recombination and poor material stability in the prior art.

[0004] (II) Technical solutions To achieve the above-mentioned purpose, the present application provides the following technical solutions: a carbon nanotube-two-dimensional perovskite heterojunction cold cathode, the raw materials and their weight proportions of the heterojunction cold cathode are as follows: carbon nanotubes 5% to 15%; two-dimensional perovskite precursor solution 20% to 30%; silver nanowires 10% to 20%; polyvinylidene fluoride adhesive 3% to 6%; conductive polymer binder 2% to 5%; dispersing agent 15% to 25%; buffer layer material 5% to 10%; antioxidant additive 1% to 5%; metal bonding layer 3% to 8%; base material 10% to 20%; interface modification layer 1% to 3%.

[0005] Preferably, the carbon nanotubes are composed of semiconductor single-walled carbon nanotubes and conductive multi-walled carbon nanotubes, the physical properties of the semiconductor single-walled carbon nanotubes are controlled in the range of 1.0-1.3nm in diameter, 5-30um in length, purity ≥95%, and carbon nanotube defect density <0.05; the number of layers of the conductive multi-walled carbon nanotubes is 5-15 layers, and the physical properties are controlled in the range of 10-30nm in outer diameter, 10-50um in length, purity >98%, and resistivity <10~ 3 Ω·cm.

[0006] Preferably, the preparation process of the two-dimensional perovskite precursor solution is as follows: S1.1, precursor metering and mixing: prepare phenethylammonium iodide, lead iodide, and methylammonium iodide in a molar ratio of 2:3:4 in an inert atmosphere glove box with water content less than 1 ppm and oxygen content less than 10 ppm; S1.2, solvent dissolution and stirring: dissolve the mixed solid powder in S1.1 in a mixed solvent composed of N,N-dimethylformamide and dimethyl sulfoxide in a molar ratio of 4:1, under the protection of nitrogen with a purity of more than 99.99%, and continuously stir at 60-70°C for 12-18 hours until complete dissolution to form a clear and transparent solution; S1.3, filtration and collection: filter the precursor solution obtained in S1.2 using a polytetrafluoroethylene needle filter with a pore size of 0.22 μm, and collect the filtrate to obtain the required two-dimensional perovskite precursor solution.

[0007] Preferably, the buffer layer material is composed of [6,6]-phenyl-C61-butyric acid methyl ester and zinc oxide nanoparticles; the metal adhesion layer is composed of silver nanoparticles, gold nanoparticles, and palladium nanoparticles; the substrate material is composed of fluorine-doped tin oxide glass and a silica transition layer; and the interface modification layer is composed of polyvinylpyrrolidone, polystyrene, and perfluorodecyltrichlorosilane.

[0008] Preferably, the conductive polymer binder is composed of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) and polyaniline; and the antioxidant additive is composed of vitamin E derivatives and hindered phenolic compounds.

[0009] Preferably, a carbon nanotube-two-dimensional perovskite heterojunction cold cathode includes the following preparation steps: Step one, raw material preparation: prepare carbon nanotubes, two-dimensional perovskite precursor solution, silver nanowires, polyvinylidene fluoride adhesive, conductive polymer binder, dispersant, buffer layer material, antioxidant additive, metal adhesion layer, substrate material, and interface modification layer according to the designed weight ratio; Step two, raw material pretreatment: acidize and surface modify the pretreated carbon nanotubes and silver nanowires, respectively, and ultrasonically clean the substrate material with deionized water for standby use; Step three, preparation of conductive composite slurry: add the pretreated carbon nanotubes, silver nanowires, polyvinylidene fluoride adhesive, conductive polymer binder, and antioxidant additive to the dispersant, and mechanically stir under water bath conditions to prepare a uniform conductive composite slurry; Step four, preparation of buffer layer and interface modification layer: spin-coat the buffer layer material on the pretreated substrate, form the buffer layer after annealing treatment, and then spin-coat the interface modification layer material on the surface of the buffer layer to obtain the interface modification layer after drying. Step five, perovskite layer preparation: the conductive composite paste is coated on the buffer layer by screen printing, and after curing treatment, the two-dimensional perovskite precursor solution is spin-coated on the conductive layer, and preheating treatment is performed to form a perovskite layer; Step six, metal bonding layer introduction and annealing treatment: the metal bonding layer material is deposited on the surface of the preheated perovskite layer by ultrasonic spraying, and then annealing treatment is performed under program-controlled temperature conditions, and after cooling, a heterojunction cold cathode is obtained.

[0010] Preferably, the carbon nanotubes and silver nanowires in step two are respectively subjected to acidification treatment and surface modification pretreatment: S2.1, the carbon nanotubes are placed in a mixture of concentrated nitric acid and concentrated sulfuric acid with a volume ratio of 3:1, refluxed at 75-80°C for 3-4 hours, then washed with deionized water to neutral pH 6.5-7.0, and dried at 60-65°C to a water content of less than 0.1wt%, to obtain carboxylated carbon nanotubes; S2.2, the silver nanowires are ultrasonically dispersed in 4.95-5.05wt% dispersant for 25-30 minutes for surface modification treatment, and then washed by centrifugation with 70%-75% ethanol for 1-3 times to remove free PVP, to obtain PVP-coated silver nanowires.

[0011] Preferably, the preparation conditions of the conductive composite paste in step three are: mechanical stirring in the dispersant under water bath conditions at 50-60°C for 4-6 hours.

[0012] Preferably, the preparation process of the buffer layer and the interface modification layer in step four is: S3.1, the buffer layer material is dissolved in a dispersant and spin-coated on the pretreated substrate at a speed of 1500-2000rpm, and annealed at 145-150°C for 30-45 minutes to form a buffer layer; S3.2, the interface modification layer material is dissolved in ethanol and spin-coated on the surface of the buffer layer at a speed of 800-1000rpm, and dried at 75-80°C for 3-5 minutes to form an interface modification layer.

[0013] Preferably, the preparation process of the perovskite layer in step five is: S4.1, the conductive composite paste is coated on the buffer layer by screen printing, with a thickness controlled at 10μm, and cured at 75-80°C for 1-1.5 hours; S4.2, the two-dimensional perovskite precursor solution is spin-coated on the conductive layer at a speed of 1500-3000rpm in a nitrogen environment with a concentration greater than 99.99%, with a thickness controlled in the range of 150-300nm, and preheated at 98-100°C for 8-10 minutes; In step six, the metal bonding layer is introduced and annealed: first, the temperature is raised to 95-100℃ at a rate of 3-5℃ / min, and held for 10-12 minutes. Then, the temperature is raised to 145-150℃ at a rate of 3-5℃ / min, and held for annealing for 25-30 minutes. Finally, the temperature is cooled to room temperature in the furnace to complete the preparation of the heterojunction cold cathode.

[0014] Compared with the prior art, the present invention provides a carbon nanotube-two-dimensional perovskite heterojunction cold cathode, which has the following beneficial effects: 1. This invention constructs an electron emission layer by combining semiconductor single-walled carbon nanotubes and conductive multi-walled carbon nanotubes, and forms a three-dimensional conductive network with silver nanowires to achieve the beneficial effects of reducing the electron emission threshold, increasing the current density, and enhancing the toughness of the conductive path. This structure optimizes the carrier injection efficiency through heterojunction interface band matching, while the high aspect ratio of silver nanowires effectively reduces the sheet resistance, solving the problems of low electron emission efficiency and easy breakage of conductive network in traditional cold cathode materials.

[0015] 2. This invention achieves the beneficial effects of inhibiting interfacial charge recombination, passivating surface defects, and blocking material degradation channels by constructing a two-layer interface engineering of buffer layer and interface modification layer in stages, combined with the introduction of antioxidant additives. Among them, the buffer layer material realizes energy level gradient matching, the interface modification layer can reduce the interface state density, and the synergistic effect of antioxidant components improves the environmental stability and service life of the device.

[0016] 3. This invention achieves beneficial effects such as regulating the quality of the perovskite crystal phase, enhancing electrode adhesion, and promoting interfacial atomic diffusion by precisely controlling the crystallization kinetics of the two-dimensional perovskite precursor solution and the gradient annealing process of the metal binder layer. The solution spin-coating process under an inert atmosphere ensures the compactness of the perovskite film, and the programmed temperature-controlled annealing effectively eliminates internal stress, enabling the metal particles to form a stable ohmic contact with the functional layer, thereby comprehensively improving the mechanical strength and long-term working stability of the device. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the fabrication process of the heterojunction cold cathode of this invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1A carbon nanotube-two-dimensional perovskite heterojunction cold cathode, raw materials and their weight proportions of the heterojunction cold cathode are as follows: carbon nanotubes 5%-15%; two-dimensional perovskite precursor solution 20%-30%; silver nanowires 10%-20%; polyvinylidene fluoride binder 3%-6%; conductive polymer binder 2%-5%; dispersant 15%-25%; buffer layer material 5%-10%; antioxidant additive 1%-5%; metal bonding layer 3%-8%; base material 10%-20%; interface modification layer 1%-3%.

[0020] Specifically, the raw materials and their functions are as shown in Table 1. Table 1

[0021] Specifically, the carbon nanotubes are composed of semiconductive single-walled carbon nanotubes and conductive multi-walled carbon nanotubes, the semiconductive single-walled carbon nanotubes are mainly of chiral indices (9, 8) and (10, 5), and the physical properties thereof are controlled in the range of diameter 1.0-1.3 nm, length 5-30 μm, purity ≥95%, and carbon nanotube defect density (ID / IG) <0.05; the conductive multi-walled carbon nanotubes are of 5-15 layers, and the physical properties thereof are controlled in the range of outer diameter 10-30 nm, length 10-50 μm, purity >98%, and resistivity <10 3 Ω·cm. Specifically, the carbon nanotubes and the two-dimensional perovskite precursor solution constitute an electron emission layer; the silver nanowires and the carbon nanotubes constitute a conductive network layer; the polyvinylidene fluoride binder and the conductive polymer binder constitute a bonding-film forming layer; the buffer layer material and the interface modification layer constitute an interface buffer layer; the dispersant and the two-dimensional perovskite precursor solution constitute a dispersion medium layer; the antioxidant additive and the interface modification layer constitute a stabilization layer; the metal bonding layer and the silver nanowires constitute a metal interconnection layer; and the base material and the metal bonding layer constitute a base support layer.

[0022] Specifically, the preparation process of the two-dimensional perovskite precursor solution is as follows: S1.1, precursor metering and mixing: mixing phenethylammonium iodide (PEAI), lead iodide (PbI2), and methylammonium iodide (MAI) in a molar ratio of 2:3:4 in an inert atmosphere glove box with water content less than 1 ppm and oxygen content less than 10 ppm; S1.2, solvent dissolution and stirring: dissolving the mixed solid powder in S1.1 in a mixed solvent composed of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a molar ratio of 4:1, under the protection of nitrogen gas with purity greater than 99.99%, and continuously stirring at 60-70°C for 12-18 hours until completely dissolved to form a clear transparent solution; S1.3, filtration and collection: the precursor solution obtained in S1.2 is filtered using a polytetrafluoroethylene (PTFE) needle filter (water / organic universal type) with a pore size of 0.22 μm to remove undissolved micro-particle impurities, and the filtrate is collected to obtain the desired two-dimensional perovskite precursor solution.

[0023] Specifically, the buffer layer material is composed of [6,6]-phenyl-C61-butyric acid methyl ester of (1-3):(1-2) and zinc oxide nanoparticles; the metal adhesive layer is composed of silver nanoparticles, gold nanoparticles and palladium nanoparticles of (5-8):(1-2):(0.5-1); the base material is composed of fluorine-doped tin oxide glass and silica transition layer of (90-95):(5-10); the interface modification layer is composed of polyvinylpyrrolidone (PVP), polystyrene (PS) and perfluorodecyltrichlorosilane of (2-4):(1-2):(0.1-0.5).

[0024] Specifically, the conductive polymer binder is composed of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) and polyaniline of (3-5):(1-2); the antioxidant additive is composed of vitamin E derivatives and hindered phenolic compounds of (1-2):(1-1.5).

[0025] Specifically, a carbon nanotube-two-dimensional perovskite heterojunction cold cathode includes the following preparation steps: Step one, raw material preparation: prepare carbon nanotubes, two-dimensional perovskite precursor solution, silver nanowires, polyvinylidene fluoride adhesive, conductive polymer binder, dispersant, buffer layer material, antioxidant additive, metal adhesive layer, base material and interface modification layer according to the designed weight ratio; Step two, raw material pretreatment: acid treatment and surface modification pretreatment are respectively carried out on carbon nanotubes and silver nanowires, and the base material is ultrasonically cleaned with deionized water for standby; Step three, conductive composite slurry preparation: after pretreatment, carbon nanotubes, silver nanowires, polyvinylidene fluoride adhesive, conductive polymer binder and antioxidant additive are added to the dispersant, and a uniform conductive composite slurry is prepared under mechanical stirring in a water bath; Step four, buffer layer and interface modification layer preparation: the buffer layer material is spin-coated on the pretreated substrate, and after annealing treatment, the buffer layer is formed, and then the interface modification layer material is spin-coated on the surface of the buffer layer, and after drying, the interface modification layer is obtained; Step five, perovskite layer preparation: the conductive composite slurry is coated on the buffer layer by screen printing, and after curing treatment, the two-dimensional perovskite precursor solution is spin-coated on the conductive layer, and after preheating treatment, the perovskite layer is formed; Step six, metal adhesion layer introduction and annealing treatment: the metal adhesion layer material is deposited on the surface of the preheated perovskite layer by ultrasonic spraying, and then annealing treatment is carried out under the condition of program temperature control, and after cooling, a heterojunction cold cathode is obtained.

[0026] Specifically, in step two, the carbon nanotubes and silver nanowires are respectively subjected to acid treatment and surface modification pretreatment: S2.1, the carbon nanotubes are placed in a mixed solution of concentrated nitric acid and concentrated sulfuric acid with a volume ratio of 3:1, and refluxed at 75-80℃ for 3-4 hours, then washed with deionized water to neutral pH value of 6.5-7.0, and dried at 60-65℃ until the water content is less than 0.1wt%, to obtain carboxylated carbon nanotubes; S2.2, the silver nanowires are ultrasonically dispersed in 4.95-5.05 wt% dispersant for 25-30 minutes for surface modification treatment, and then washed by centrifugation with 70%-75% ethanol for 1-3 times to remove free PVP, to obtain PVP-coated silver nanowires.

[0027] Advantages: by introducing carboxyl groups through strong acid oxidation, surface modifier coating modification, precise control of treatment temperature and time, the purpose of improving the dispersion stability of nanomaterials, enhancing the interface bonding ability, effectively removing impurities and obtaining ideal surface functionalization effect is achieved.

[0028] Specifically, in step three, the preparation conditions of the conductive composite slurry are: in the dispersant, mechanical stirring for 4-6 hours under water bath at 50-60℃.

[0029] Advantages: by optimizing the solvent system, controlling the appropriate water bath temperature, and ensuring sufficient mechanical stirring time, the purpose of realizing high uniformity of each component, forming a stable conductive network structure, preventing nanomaterial agglomeration and ensuring the process applicability of the slurry is achieved.

[0030] Specifically, in step four, the preparation process of the buffer layer and the interface modification layer: S3.1, the buffer layer material is dissolved in the dispersant, and is spin-coated on the pretreated substrate at a speed of 1500-2000 rpm, and is annealed at 145-150℃ for 30-45 minutes to form a buffer layer; S3.2, the interface modification layer material is dissolved in ethanol, and is spin-coated on the surface of the buffer layer at a speed of 800-1000 rpm, and is dried at 75-80℃ for 3-5 minutes to form an interface modification layer.

[0031] Advantages: by step-by-step spin coating, precise control of annealing temperature and time, selection of appropriate solvent and speed, the purpose of forming a dense and uniform electron transport layer, effectively modifying the interface energy level, passivating surface defects and enhancing the adhesion between functional layers is achieved.

[0032] Specifically, the perovskite layer preparation process in step five: S4.1. The conductive composite paste is coated onto the buffer layer by screen printing, with a thickness controlled at 10μm, and cured at 75-80℃ for 1 to 1.5 hours. S4.2 In a nitrogen atmosphere with a concentration greater than 99.99%, spin-coat the two-dimensional perovskite precursor solution onto the conductive layer at a speed of 1500-3000 rpm, with the thickness controlled in the range of 150-300 nm, and preheat at 98-100℃ for 8-10 minutes. The advantages are: by protecting the film with an inert atmosphere, the film thickness and spin coating parameters can be precisely controlled, and a stepped preheating treatment can be used to prevent oxidation of the perovskite precursor, obtain a crystalline active layer without pores, promote the initial nucleation of crystals, and lay the foundation for subsequent annealing.

[0033] Specifically, in step six, the metal bonding layer is introduced and annealed: first, the temperature is raised to 95-100℃ at a rate of 3-5℃ / min, and held for 10-12 minutes. Then, the temperature is raised to 145-150℃ at a rate of 3-5℃ / min, and held for annealing for 25-30 minutes. Finally, the temperature is cooled to room temperature in the furnace to complete the preparation of the heterojunction cold cathode.

[0034] The advantages are: by using programmed temperature control for heating, staged heat preservation treatment, and finally natural cooling, the internal stress is eliminated, the perovskite grains are fully grown and healed, the interface contact is optimized, and finally a stable, efficient, and mechanically sound heterojunction cold cathode is formed.

[0035] A laboratory team conducted material preparation and performance comparison tests, obtaining comparative examples of the embodiments of this invention and traditional methods, as detailed below: Example 1 According to the raw material ratio and preparation method described in this invention, a heterojunction cold cathode sample was prepared by using a ratio of semiconductor single-walled carbon nanotubes to conductive multi-walled carbon nanotubes of 4:1, a ratio of PCBM to ZnO nanoparticles in the buffer layer material of 2:1, and a ratio of silver, gold, and palladium nanoparticles in the metal bonding layer of 7:1.5:0.8.

[0036] Compared with Example 1, Comparative Example 1 did not add silver nanowires, but the other raw materials and preparation processes were exactly the same.

[0037] Example 2 According to the raw material ratio and preparation method described in this invention, the proportion of the two-dimensional perovskite precursor solution was adjusted to 25%, the ratio of PVP, PS and perfluorodecyltrichlorosilane in the interface modification layer was 3:1.5:0.3, and the annealing treatment adopted a two-stage programmed temperature rise to prepare a heterojunction cold cathode sample.

[0038] Comparative Example 2 Compared with Example 2, the interface modification layer preparation step is omitted, and the rest of the raw materials and preparation process are completely the same.

[0039] Example 3 According to the raw material ratio and preparation method described in the application, the ratio of vitamin E derivative to hindered phenolic compound in the antioxidant additive is 1.5:1.2, and the particle size of silver nanoparticles in the metal bonding layer is controlled at 50 nm, and the heterojunction cold cathode sample is prepared.

[0040] Comparative Example 3 Compared with Example 3, no antioxidant additive is added, and the rest of the raw materials and preparation process are completely the same.

[0041] The examples and comparative examples are all prepared into finished products according to the above-mentioned raw materials and preparation methods, and performance tests are carried out, and the test data are as follows in Table 2: Table 2 Comparison of performance test results of examples and comparative examples

[0042] Note: The test conditions are room temperature, high vacuum environment (10 -6 Pa), and the distance between the anode and the cathode is 50 μm.

[0043] From Table 2, it can be seen that: Examples 1-3 all show lower turn-on electric field, higher emission current density, and excellent stability and life, and comparative examples 1-3 all show obvious decrease in different performance indicators, which finally verifies that the examples of the application solve the problems of low electron emission efficiency, serious interface recombination and poor material stability in the traditional technology through optimized material combination and preparation process, and achieve the beneficial effects of significantly improving the cold cathode electron emission performance, enhancing the device stability and prolonging the service life.

[0044] Although the embodiments of the application have been shown and described, it can be understood by those of ordinary skill in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the application, and the scope of the application is defined by the appended claims and their equivalents.

Claims

1. A carbon nanotube-two-dimensional perovskite heterojunction cold cathode, characterized in that, The raw materials and their weight percentages for the heterojunction cold cathode are as follows: carbon nanotubes 5%–15%; two-dimensional perovskite precursor solution 20%–30%; silver nanowires 10%–20%; polyvinylidene fluoride adhesive 3%–6%; conductive polymer binder 2%–5%; dispersant 15%–25%; buffer layer material 5%–10%; antioxidant additive 1%–5%; metal bonding layer 3%–8%; substrate material 10%–20%; and interface modification layer 1%–3%.

2. The carbon nanotube-two-dimensional perovskite heterojunction cold cathode according to claim 1, characterized in that, The carbon nanotubes are composed of semiconducting single-walled carbon nanotubes and conductive multi-walled carbon nanotubes. The physical properties of the semiconducting single-walled carbon nanotubes are controlled within the range of diameter 1.0-1.3 nm, length 5-30 μm, purity ≥95%, and carbon nanotube defect density <0.

05. The conductive multi-walled carbon nanotubes have 5-15 layers, and their physical properties are controlled within the range of outer diameter 10-30 nm, length 10-50 μm, purity >98%, and resistivity <10 Ω·cm. -3 The range of Ω·cm.

3. The carbon nanotube-two-dimensional perovskite heterojunction cold cathode according to claim 1, characterized in that, The preparation process of the two-dimensional perovskite precursor solution is as follows: S1.1, Precursor metering and mixing: Prepare phenylethyl ammonium iodide, lead iodide and methyl ammonium iodide in a molar ratio of 2:3:4 and mix them in an inert atmosphere glove box with a moisture content of less than 1 ppm and an oxygen content of less than 10 ppm. S1.2 Solvent Dissolution and Stirring: Dissolve the solid powder mixed in S1.1 in a mixed solvent consisting of N,N-dimethylformamide and dimethyl sulfoxide in a molar ratio of 4:

1. Under nitrogen protection with a purity greater than 99.99%, stir continuously at 60-70°C for 12-18 hours until completely dissolved to form a clear and transparent solution. S1.3 Filtration and Collection: The precursor solution obtained in S1.2 is filtered using a polytetrafluoroethylene needle filter with a pore size of 0.22 μm. The filtrate is collected to obtain the desired two-dimensional perovskite precursor solution.

4. The carbon nanotube-two-dimensional perovskite heterojunction cold cathode according to claim 1, characterized in that, The buffer layer material is composed of methyl [6,6]-phenyl-C61-butyrate and zinc oxide nanoparticles; the metal bonding layer is composed of silver nanoparticles, gold nanoparticles and palladium nanoparticles; the substrate material is composed of fluorine-doped tin oxide glass and a silicon dioxide transition layer; the interface modification layer is composed of polyvinylpyrrolidone, polystyrene and perfluorodecyltrichlorosilane.

5. The carbon nanotube-two-dimensional perovskite heterojunction cold cathode according to claim 1, characterized in that, The conductive polymer binder is composed of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) and polyaniline; the antioxidant additive is composed of vitamin E derivatives and hindered phenolic compounds.

6. The carbon nanotube-two-dimensional perovskite heterojunction cold cathode according to claim 1, characterized in that, The preparation steps include the following: Step 1: Raw material preparation: Prepare carbon nanotubes, two-dimensional perovskite precursor solution, silver nanowires, polyvinylidene fluoride adhesive, conductive polymer binder, dispersant, buffer layer material, antioxidant additive, metal bonding layer, substrate material and interface modification layer according to the designed weight ratio. Step 2, Raw material pretreatment: Carbon nanotubes and silver nanowires are subjected to acidification and surface modification pretreatment respectively. The substrate material is ultrasonically cleaned with deionized water and set aside. Step 3: Preparation of conductive composite slurry: The pretreated carbon nanotubes, silver nanowires, polyvinylidene fluoride adhesive, conductive polymer binder, and antioxidant additives are added to the dispersant and mechanically stirred under water bath conditions to prepare a uniform conductive composite slurry. Step 4: Preparation of buffer layer and interface modification layer: Spin-coat the buffer layer material onto the pretreated substrate, anneal it to form a buffer layer, then spin-coat the interface modification layer material onto the surface of the buffer layer, and dry it to obtain the interface modification layer. Step 5, perovskite layer preparation: The conductive composite paste is coated onto the buffer layer by screen printing and cured. Then, the two-dimensional perovskite precursor solution is spin-coated onto the conductive layer and preheated to form the perovskite layer. Step 6, Introduction and Annealing of Metal Bonding Layer: The metal bonding layer material is deposited on the surface of the preheated perovskite layer by ultrasonic spraying, and then annealed under programmed temperature control. After cooling, a heterojunction cold cathode is obtained.

7. The carbon nanotube-two-dimensional perovskite heterojunction cold cathode according to claim 6, characterized in that, In step two, carbon nanotubes and silver nanowires undergo acidification treatment and surface modification pretreatment, respectively. S2.

1. Place carbon nanotubes in a mixture of concentrated nitric acid and concentrated sulfuric acid at a volume ratio of 3:1, reflux at 75-80℃ for 3-4 hours, then wash with deionized water until the neutral pH value is 6.5-7.0, and dry at 60-65℃ until the moisture content is less than 0.1wt% to obtain carboxylated carbon nanotubes. S2.

2. The silver nanowires are ultrasonically dispersed in 4.95-5.05 wt% dispersant for 25-30 minutes to perform surface modification treatment, and then washed by centrifugation with 70%-75% ethanol for 1-3 times to remove free PVP, thus obtaining PVP-coated silver nanowires.

8. The carbon nanotube-two-dimensional perovskite heterojunction cold cathode according to claim 6, characterized in that, The preparation conditions for the conductive composite slurry in step three are as follows: mechanical stirring in a dispersant at a water bath temperature of 50-60°C for 4-6 hours.

9. A carbon nanotube-two-dimensional perovskite heterojunction cold cathode according to claim 6, characterized in that, The preparation process of the buffer layer and interface modification layer in step four: S3.1 Dissolve the buffer layer material in the dispersant, spin coat it onto the pretreated substrate at a speed of 1500-2000 rpm, and anneal at 145-150℃ for 30-45 minutes to form a buffer layer; S3.2 Dissolve the interface modification layer material in ethanol, spin coat it onto the surface of the buffer layer at 800-1000 rpm, and dry it at 75-80℃ for 3-5 minutes to form the interface modification layer.

10. A carbon nanotube-two-dimensional perovskite heterojunction cold cathode according to claim 6, characterized in that, The perovskite layer preparation process in step five: S4.

1. The conductive composite paste is coated onto the buffer layer by screen printing, with a thickness controlled at 10μm, and cured at 75-80℃ for 1 to 1.5 hours. S4.2 In a nitrogen atmosphere with a concentration greater than 99.99%, spin-coat the two-dimensional perovskite precursor solution onto the conductive layer at a speed of 1500-3000 rpm, with the thickness controlled in the range of 150-300 nm, and preheat at 98-100℃ for 8-10 minutes. In step six, the metal bonding layer is introduced and annealed: first, the temperature is raised to 95-100℃ at a rate of 3-5℃ / min, and held for 10-12 minutes. Then, the temperature is raised to 145-150℃ at a rate of 3-5℃ / min, and held for annealing for 25-30 minutes. Finally, the temperature is cooled to room temperature in the furnace to complete the preparation of the heterojunction cold cathode.

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