Nickel oxide-based thin film, preparation method and application thereof, composite nickel oxide-based thin film and application thereof

Abstract

The invention provides a nickel oxide-based thin film, a preparation method and application thereof, a composite nickel oxide-based thin film and application thereof, and particularly relates to the technical field of thin films. The preparation method provided by the invention comprises the following steps: mixing and grinding a nickel source, doped metal salt and a solvent to obtain mixed slurry; coating a base plate with the mixed slurry, attaching the base plate to a substrate, and pressurizing to obtain a composite base plate; the composite substrate is heated, the nickel oxide-based thin film is obtained on the surface of the substrate, the heating temperature ranges from 100 DEG C to 400 DEG C, and the oxygen partial pressure ranges from 10 Pa to 80 Pa. According to the method, doping ions are introduced by adopting a chemical solution method, so that the energy band structure of the nickel oxide-based thin film is regulated and controlled, and the doping ions are ensured to be uniformly embedded into nickel oxide crystal lattices; crystal grain growth is controlled by adopting a plane fitting pressurizing heat treatment process; the nickel valence state is further regulated through heat treatment, and the conductivity of the film is improved; and the service life of the perovskite cell is prolonged through evaporation of the modification layer.

Description

Technical Field

[0001] The invention belongs to the technical field of film preparation, and specifically relates to a nickel oxide-based film and a preparation method and application thereof, and a composite nickel oxide-based film and application thereof. Background Art

[0002] Nickel oxide is a wide bandgap p-type semiconductor material with high transmittance in the visible light range. The valence band top energy level is around -5.1eV, which matches the perovskite energy level and is suitable as a hole transport layer material for perovskite cells.

[0003] At present, the preparation methods of nickel oxide thin films include thermal evaporation, sol-gel method, magnetron sputtering, etc., but these coating processes have low film forming efficiency, unstable coating process, high film making cost, and the prepared nickel oxide-based thin films have uneven thickness and poor conductivity, which restricts the development of nickel oxide-based thin films in application fields that need to utilize their conductivity. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a nickel oxide-based film and a preparation method and application thereof, a composite nickel oxide-based film and application thereof. The preparation method provided by the present invention has high film forming efficiency and low film making cost, and the obtained film has good conductivity and uniform thickness.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a nickel oxide-based film, comprising the following steps:

[0007] The nickel source, the doping metal salt and the solvent are mixed and ground to obtain a mixed slurry;

[0008] The mixed slurry is coated on a substrate, and then the substrate is attached and pressed to obtain a composite substrate;

[0009] The composite substrate is heated to obtain a nickel oxide-based thin film on the surface of the substrate, the heating temperature is 100-400° C., and the oxygen partial pressure is 10-80 Pa.

[0010] Preferably, the molar amount of the nickel source is 80-98% of the total molar amount of the nickel source and the doping metal salt.

[0011] Preferably, the nickel source includes at least one of nickel oxide, nickel trioxide, nickel hydroxide, nickel sulfate, nickel chloride, nickel nitrate and nickel acetate;

[0012] The metal in the doped metal salt includes at least one of Li, Mg, Sc, Ti, V, Mn, Fe, Co, Cu, Zn, Ga, Sr, Y, Nb, Mo, Ag, In, Sn, Cs, La, Ce, Ta, W, Au and Pb.

[0013] Preferably, the mixed slurry is coated to a thickness of 1 to 50 μm.

[0014] Preferably, the total mass of the nickel source and the doping metal salt accounts for 10-50% of the mass of the mixed slurry.

[0015] Preferably, the pressurized pressure is 1-10 MPa, and the pressure holding time is 0.5-4 h.

[0016] Preferably, the heating time is 10 to 120 minutes.

[0017] The present invention also provides a nickel oxide-based film prepared by the preparation method described in the above technical solution.

[0018] The present invention also provides a composite nickel oxide-based film, comprising the nickel oxide-based film described in the above technical solution and a modification layer evaporated on the surface of the nickel oxide-based film; the modification layer comprises at least one of lithium fluoride, lithium bis(trifluoromethylsulfonyl)imide and 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline.

[0019] The present invention also provides the use of the composite nickel oxide-based film described in the above technical solution as a hole transport layer in a perovskite battery.

[0020] The invention provides a method for preparing a nickel oxide-based film, comprising the following steps: mixing and grinding a nickel source, a doped metal salt and a solvent to obtain a mixed slurry; coating the mixed slurry on a substrate, laminating the substrate, and applying pressure to obtain a composite substrate; heating the composite substrate to obtain a nickel oxide-based film on the surface of the substrate, wherein the heating temperature is 100-400°C and the oxygen partial pressure is 10-80Pa. The present invention introduces new energy levels or orbital hybridizations through element doping, changes the valence band structure, and realizes the regulation of the energy band structure of nickel oxide-based thin films, so that it meets the energy level matching requirements of different perovskite battery materials; introduces doping ions by a chemical solution method to ensure that the doping ions are uniformly embedded in the nickel oxide lattice, changes the energy level structure of nickel oxide, thereby introducing nickel vacancies and improving the conductivity of the nickel oxide film; grows nickel oxide-based thin films on substrates using a plane-fitting pressurized heat treatment process, which is conducive to controlling grain growth, improving film density, and avoiding local grain-rich aggregation; by optimizing the heat treatment process and adjusting the heat treatment atmosphere, the valence state, grain size and density of nickel in the nickel oxide-based thin film are further regulated to improve the conductivity of the film. The preparation method provided by the present invention has high film-forming efficiency and low film-making cost, which is conducive to industrial production.

[0021] The present invention provides a composite nickel oxide-based film, which improves the interface contact between the film and the perovskite material, inhibits contact side reactions, and prolongs the life of the perovskite battery by evaporating a modification layer on the surface of the nickel oxide-based film.

[0022] The results of the examples show that the average thickness of the nickel oxide-based film prepared by the present invention is 20 to 30 nm. The composite nickel oxide-based film obtained by evaporating the modified layer on the nickel oxide-based film has a carrier concentration of 4.00×10 19 ~2.78×10 20 / cm3, the mobility of the composite film is 0.47~1.25cm2 / V·s, the resistivity of the composite film is 0.025~0.287Ω·cm, and the transmittance of the composite film is 75.4~87.5%, which has good conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 This is the SEM image of the nickel oxide-based film prepared in Example 1. DETAILED DESCRIPTION

[0025] The present invention provides a method for preparing a nickel oxide-based film, comprising the following steps:

[0026] The nickel source, the doping metal salt and the solvent are mixed and ground to obtain a mixed slurry;

[0027] The mixed slurry is coated on a substrate, and then the substrate is attached and pressed to obtain a composite substrate;

[0028] The composite substrate is heated to obtain a nickel oxide-based thin film on the surface of the substrate, the heating temperature is 100-400° C., and the oxygen partial pressure is 10-80 Pa.

[0029] In the present invention, unless otherwise specified, the raw materials and equipment used are commercially available products well known in the art.

[0030] The invention mixes and grinds a nickel source, a doped metal salt and a solvent to obtain a mixed slurry.

[0031] In the present invention, the nickel source comprises at least one of nickel oxide, nickel trioxide, nickel hydroxide, nickel sulfate, nickel chloride, nickel nitrate and nickel acetate. In the present invention, the molar amount of the nickel source is preferably 80-98% of the total molar amount of the nickel source and the doped metal salt. In a specific embodiment, the molar amount of the nickel source can be 80%, 82%, 85%, 87%, 90%, 92%, 95% or 98% of the total molar amount of the nickel source and the doped metal salt. In the present invention, the purity of the nickel source is >99.9%.

[0032] In the present invention, the metal in the doped metal salt includes at least one of Li, Mg, Sc, Ti, V, Mn, Fe, Co, Cu, Zn, Ga, Sr, Y, Nb, Mo, Ag, In, Sn, Cs, La, Ce, Ta, W, Au and Pb. In the present invention, the molar amount of the doped metal salt is preferably 2-20% of the total molar amount of the nickel source and the doped metal salt. In a specific embodiment, the molar proportion of the doped metal salt can be 2%, 5%, 8%, 10%, 13%, 15%, 18% or 20%. In the present invention, the purity of the doped metal salt is >99.9%. By element doping, new energy levels or orbital hybridization are introduced to achieve the regulation of the band structure of nickel oxide-based thin films, so that it meets the energy level matching requirements of different perovskite battery materials.

[0033] In the present invention, the solvent preferably includes at least one of water, sulfuric acid, nitric acid, hydrochloric acid, ammonia, acetone, ethanol, acetic acid, and ethyl acetate. In a specific embodiment, the solvent preferably includes water or ethanol aqueous solution. In the present invention, the mass ratio of water to ethanol in the ethanol aqueous solution is preferably 0.05:0.95. Using ethanol aqueous solution as a solvent can reduce the temperature of the heat treatment process.

[0034] In the present invention, the total mass of the nickel source and the doped metal salt preferably accounts for 10-50% of the mass of the mixed slurry. In a specific embodiment, the total mass of the nickel source and the doped metal salt accounts for 10%, 20%, 30%, 35%, 40%, 45% or 50% of the mass of the mixed slurry.

[0035] In the present invention, the mixed grinding preferably uses a sand mill, and the grinding speed of the sand mill is preferably 1800-2500rpm. In a specific embodiment, the grinding speed can be 1800rpm, 2000rpm, 2200rpm or 2500rpm; the grinding time is preferably 3-5h. In a specific embodiment, the grinding time can be 3h, 4h or 5h.

[0036] After obtaining the mixed slurry, the present invention applies the mixed slurry on a substrate, adheres the substrate, and applies pressure to obtain a composite substrate.

[0037] In the present invention, the thickness of the mixed slurry coating is preferably 1 to 50 μm. In a specific embodiment, the thickness of the mixed slurry coating can be 1 μm, 2 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm or 50 μm.

[0038] In the present invention, the substrate preferably includes a nickel substrate, an iron substrate, a steel substrate, a copper substrate, an aluminum substrate, a silver substrate, a quartz substrate, a glass substrate or a plastic substrate.

[0039] The present invention has no special requirements on the bonding method, and the commonly used technical means in the art can be used.

[0040] In the present invention, the substrate is preferably TCO glass.

[0041] In the present invention, the pressurized pressure is preferably 1-10 MPa. In a specific embodiment, the pressurized pressure can be 1 MPa, 2 MPa, 5 MPa, 8 MPa or 10 MPa. The holding time is preferably 0.5-4 h. In a specific embodiment, the holding time can be 0.5 h, 0.75 h, 1 h, 2 h, 3 h or 4 h.

[0042] The composite substrate is obtained. The present invention heats the composite substrate to obtain a nickel oxide-based thin film on the surface of the substrate.

[0043] In the present invention, the heating temperature is 100-400°C. In a specific embodiment, the heating temperature can be 100°C, 120°C, 150°C, 170°C, 200°C, 230°C, 260°C, 270°C, 300°C, 350°C or 400°C. The oxygen partial pressure is 10-80Pa. In a specific embodiment, the oxygen partial pressure can be 10Pa, 20Pa, 30Pa, 40Pa, 50Pa, 60Pa, 70Pa or 80Pa. In the present invention, the heating time is preferably 10-120min. In a specific embodiment, the heating time can be 10min, 30min, 50min, 60min, 800min, 100min or 120min.

[0044] In the present invention, after the composite substrate is heated, a nickel oxide-based thin film is grown on the substrate, and preferably the substrate and the nickel oxide-based thin film are separated to obtain the nickel oxide-based thin film.

[0045] In the present invention, the thickness of the nickel oxide-based film is preferably 20 to 30 nm. In a specific embodiment, the thickness of the nickel oxide-based film may be 20 nm, 22 nm, 25 nm, 27 nm or 30 nm.

[0046] The present invention has no special requirements on the separation method and the commonly used technical means in the art can be used.

[0047] The present invention also provides a nickel oxide-based film prepared by the preparation method described in the above technical solution. The nickel oxide-based film prepared by the method provided by the present invention has no metal content loss during the film forming process.

[0048] In the present invention, the average thickness of the nickel oxide-based film is preferably 20 to 30 nm. In a specific embodiment, the average thickness of the nickel oxide-based film may be 20 nm, 22 nm, 24 nm, 26 nm, 28 nm or 30 nm.

[0049] The present invention also provides a composite nickel oxide-based film, comprising the nickel oxide-based film described in the above technical solution and a modification layer evaporated on the surface of the nickel oxide-based film; the modification layer comprises at least one of lithium fluoride, lithium bis(trifluoromethylsulfonyl)imide and 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline.

[0050] In the present invention, the evaporation is preferably performed by electron beam evaporation, the evaporation temperature is preferably room temperature, and the evaporation time is preferably determined by the thickness of the modification layer.

[0051] In the present invention, the thickness of the modified layer is preferably 1 to 20 nm. In a specific embodiment, the thickness of the modified layer may be 1 nm, 3 nm, 5 nm, 8 nm, 10 nm, 13 nm, 15 nm or 20 nm.

[0052] The composite nickel oxide-based thin film obtained by the present invention has a carrier concentration of preferably 4.00×10 19 ~2.78×10 20 / cm3, the composite film mobility is preferably 0.47-1.25cm2 / V·s, the composite film resistivity is preferably 0.025-0.287Ω·cm, and the composite film transmittance is preferably 75.4-87.5%.

[0053] The present invention also provides the use of the nickel oxide-based film described in the above technical solution and the composite nickel oxide-based film as a hole transport layer in a perovskite battery.

[0054] The present invention has no special requirements for the application method and any technical means known in the art may be used.

[0055] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described in conjunction with specific embodiments below. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Any modification, equivalent replacement, improvement, etc. made to the implementation methods of the present invention based on the technical essence and general principles of the present invention without creative work should be within the scope of protection of the present invention.

[0056] Example 1

[0057] Nickel hydroxide powder, lithium carbonate powder and silver nitrate powder were mixed in a molar ratio of 9:0.5:0.5, pure water was added, the solid content was controlled to be 40wt%, and the mixture was put into a sand mill at 2000rpm for 4h to obtain a mixed slurry. After the mixed slurry with a thickness of 2μm was coated on the nickel substrate, the TCO glass was bonded to the nickel substrate coated with the mixed slurry, and the pressure was maintained at 5MPa for 30min to obtain a composite substrate.

[0058] The composite substrate was placed in a heating furnace and kept warm for 30 minutes at an oxygen partial pressure of 20 Pa and 200° C. to grow a nickel oxide-based thin film on the surface of the TCO glass.

[0059] A simple physical separation method was used to separate the nickel substrate from the TCO glass. The TCO glass covered with the nickel oxide-based film was placed in a reaction chamber. Electron beam evaporation was used to evaporate a 10nm LiF (lithium fluoride) modification layer on the surface of the nickel oxide-based film at room temperature to obtain a composite nickel oxide-based film.

[0060] Example 2

[0061] Nickel nitrate powder, lithium carbonate powder and silver nitrate powder were mixed in a molar ratio of 9:0.8:0.2, and the mixed slurry with a thickness of 10 μm was coated on a nickel substrate. The mixed slurry was kept at 2 MPa for 50 min and placed in a heating furnace with an oxygen partial pressure of 80 Pa and a temperature of 150° C. for 30 min. Other conditions were the same as those in Example 1.

[0062] Example 3

[0063] Nickel hydroxide powder, copper oxide powder and silver nitrate powder were mixed in a molar ratio of 9:0.7:0.3, and the mixed slurry with a thickness of 5 μm was coated on a nickel substrate. The substrate was placed in a heating furnace with an oxygen partial pressure of 80 Pa and a temperature of 170°C for 30 min, and a 10 nm LiTFSI (lithium bis(trifluoromethylsulfonyl)imide) modification layer was evaporated. The other conditions were the same as those in Example 1.

[0064] Example 4

[0065] Nickel chloride powder, magnesium oxide powder and cesium chloride powder were mixed in a molar ratio of 9:0.9:0.1, and the mixed slurry with a thickness of 20 μm was coated on a nickel substrate. The mixed slurry was placed in a heating furnace with an oxygen partial pressure of 20 Pa and a temperature of 260° C. for 50 min. Other conditions were the same as those in Example 1.

[0066] Example 5

[0067] Mix nickel nitrate powder, zinc oxide powder and silver nitrate powder in a molar ratio of 8.5:0.5:1, add ethanol water (m 乙醇 / m 水 =0.95:0.05) as a solvent, a mixed slurry with a thickness of 20 μm was coated on a nickel substrate, and the substrate was placed in a heating furnace with an oxygen partial pressure of 50 Pa and a temperature of 200° C. for 30 min. Other conditions were the same as in Example 1.

[0068] Example 6

[0069] Mix nickel hydroxide powder, yttrium oxide powder and silver nitrate powder in a molar ratio of 9.2:0.2:0.6, add ethanol water (m 乙醇 / m 水 =0.95:0.05) as a solvent, the solid content is controlled to be 30wt%, and the mixed slurry with a thickness of 20μm is coated on a nickel substrate, placed in a heating furnace, oxygen partial pressure of 50Pa, 200℃ for 30min, and a 10nm LiTFSI modification layer is evaporated. The other conditions are the same as in Example 1.

[0070] Example 7

[0071] Mix nickel hydroxide powder, vanadium pentoxide powder and tantalum pentoxide powder in a molar ratio of 9.6:0.2:0.2, add ethanol water (m 乙醇 / m 水 =0.95:0.05) as a solvent, the solid content is controlled to be 30wt%, and the mixed slurry with a thickness of 30μm is coated on a nickel substrate, and placed in a heating furnace with an oxygen partial pressure of 50Pa and a temperature of 200℃ for 60min. Other conditions are the same as in Example 1.

[0072] Example 8

[0073] Mix nickel oxide powder, manganese carbonate powder and indium oxide powder in a molar ratio of 9:0.5:0.5, add ethanol water (m 乙醇 / m 水 =0.95:0.05) as a solvent, control the solid content to 50wt%, apply the mixed slurry with a thickness of 10μm on a nickel substrate, place it in a heating furnace, keep it at 200℃ for 30min with an oxygen partial pressure of 50Pa, and evaporate a 10nm BCP (2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline) modification layer. The other conditions are the same as those in Example 1.

[0074] Example 9

[0075] Mix nickel acetate powder, titanium dioxide powder and strontium oxide powder in a molar ratio of 8.5:0.5:1, add ethanol water (m 乙醇 / m 水 =0.95:0.05) as a solvent, the solid content is controlled to be 45wt%, and the mixed slurry with a thickness of 10μm is coated on a nickel substrate, placed in a heating furnace, oxygen partial pressure of 50Pa, 270℃ for 30min, and a 10nm BCP modification layer is evaporated. The other conditions are the same as in Example 1.

[0076] Example 10

[0077] Mix nickel powder, iron oxide powder and tin oxide powder in a molar ratio of 9.5:0.3:0.2, add ethanol water (m 乙醇 / m 水 =0.95:0.05) as a solvent, the solid content is controlled to be 30wt%, and the mixed slurry with a thickness of 5μm is coated on a nickel substrate. The mixed slurry is kept at 2MPa for 30min, placed in a heating furnace, oxygen partial pressure of 30Pa, and 120℃ for 120min, and a 10nm LiTFSI modification layer is evaporated. The other conditions are the same as those in Example 1.

[0078] Comparative Example 1

[0079] Nickel hydroxide powder was mixed with water to control the solid content to 40 wt %. Other conditions were the same as those in Example 1.

[0080] Comparative Example 2

[0081] The composite substrate was placed in a heating furnace under a nitrogen atmosphere at 200° C. for 30 min. Other conditions were the same as those in Example 1.

[0082] Comparative Example 3

[0083] Nickel hydroxide powder was mixed with water to control the solid content to 40 wt %. The composite substrate was placed in a heating furnace under a nitrogen atmosphere at 200° C. for 30 min. Other conditions were the same as those in Example 1.

[0084] The composite nickel oxide-based films obtained in Examples 1 to 10 and Comparative Examples 1 to 3 were cut into 10×10 mm squares, and the resistivity, mobility, and carrier concentration of the films were tested using a CH-50 Hall effect instrument, and the transmittance of the films in the 300 to 1400 nm band was tested using a Cary 5000 UV spectrophotometer. The results are shown in Table 1. Table 1 Resistivity, mobility, carrier concentration, and transmittance of the composite nickel oxide-based films obtained in Examples 1 to 10 and Comparative Examples 1 to 3

[0085]

[0086]

[0087] From Table 1, it can be seen that the resistivity of the composite nickel oxide-based film prepared in Comparative Example 3 is higher than 10 6 Ω·cm, poor conductivity. If it is directly used as a hole transport layer for perovskite cells, it will greatly limit the photoelectric conversion efficiency of perovskite cells. Examples 1 to 10 all use ion doping and oxygen atmosphere heat treatment processes, and the resistivity of the resulting films is all lower than 1Ω·cm. Nickel oxide relies on nickel vacancy defects in the lattice to achieve conductivity. The ionic radius of the doped ions is different from that of nickel, causing crystal structure distortion and increasing the concentration of nickel vacancy defects, i.e., Ni 3+ The ratio increases, and the macroscopic manifestation is a decrease in resistivity. Judging from the measured film resistivity data, the composite nickel oxide-based thin films prepared in Examples 1 to 10 have a high nickel vacancy defect concentration and good electrical conductivity. At the same time, the present invention adjusts the doping formula through a chemical solvent method, introduces doping ions into the nickel oxide lattice, and produces nickel vacancies, which can greatly improve the electrical conductivity of the film, improve the light transmittance, and thus improve the photoelectric conversion efficiency of the perovskite cell. Judging from the data results of the average transmittance, the average transmittance of the composite nickel oxide-based thin film obtained in Example 1 in the 300-1400nm band is >87%. When the transmittance is high, the material absorbs less light of a specific wavelength, and the band gap width of the material is also wider, proving that the obtained composite nickel oxide-based thin film nickel has high transmittance and high photoelectric conversion efficiency.

[0088] The composite nickel oxide-based film prepared in Example 1 was subjected to SEM electron microscope scanning. Figure 1 As shown in the figure, it can be seen that the film has no obvious defects (large particles, pores and local defects, etc.) at the microscopic level, the average thickness of the film is 24.39nm, the film quality is good, and the overall consistency and flatness of the film are good.

[0089] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a nickel oxide-based thin film, characterized in that: The following steps are involved: The nickel source, the doping metal salt and the solvent are mixed and ground to obtain a mixed slurry; The mixed slurry is coated on a substrate, and then bonded to a substrate, and pressed to obtain a composite substrate; The composite substrate is heated to obtain a nickel oxide-based thin film on the surface of the substrate, the heating temperature is 100-400° C., and the oxygen partial pressure is 10-80 Pa.

2. The preparation method according to claim 1, characterized in that: The molar amount of the nickel source is 80-98% of the total molar amount of the nickel source and the doping metal salt.

3. The preparation method according to claim 1 or 2, characterized in that: The nickel source comprises at least one of nickel oxide, nickel trioxide, nickel hydroxide, nickel sulfate, nickel chloride, nickel nitrate and nickel acetate; The metal in the doped metal salt includes at least one of Li, Mg, Sc, Ti, V, Mn, Fe, Co, Cu, Zn, Ga, Sr, Y, Nb, Mo, Ag, In, Sn, Cs, La, Ce, Ta, W, Au and Pb.

4. The preparation method according to claim 1, characterized in that: The mixed slurry is coated with a thickness of 1 to 50 μm.

5. The preparation method according to claim 1 or 2, characterized in that: The total mass of the nickel source and the doped metal salt accounts for 10-50% of the mass of the mixed slurry.

6. The preparation method according to claim 1, characterized in that: The pressurizing pressure is 1-10 MPa, and the pressure holding time is 0.5-4 h.

7. The preparation method according to claim 1, characterized in that: The heating time is 10 to 120 minutes.

8. The nickel oxide-based thin film prepared by the preparation method according to any one of claims 1 to 7.

9. A composite nickel oxide-based film, characterized in that: It comprises the nickel oxide-based film according to claim 8 and a modification layer evaporated on the surface of the nickel oxide-based film; the modification layer comprises at least one of lithium fluoride, lithium bis(trifluoromethylsulfonyl)imide and 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline.

10. Use of the nickel oxide-based film according to claim 8 or the composite nickel oxide-based film according to claim 9 as a hole transport layer in a perovskite battery.

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