Uniformly dispersed nickel oxide film and preparation method and application thereof

Abstract

The invention discloses a uniformly dispersed nickel oxide film and a preparation method and application thereof, and the preparation method comprises the following steps: dispersing nickel oxide nanocrystals in water, adding an alcohol solvent, and carrying out ultrasonic treatment to obtain a first dispersion liquid; adding an ionic dispersant into the first dispersion liquid, carrying out ultrasonic treatment, and filtering to obtain a second dispersion liquid; and coating a conductive substrate with the second dispersion liquid, and carrying out blow-drying, annealing and UV treatment to obtain the nickel oxide film. According to the preparation method, the nickel oxide dispersion liquid with good dispersity and stability is obtained by adopting water-alcohol mixing and dissolving and adding the ionic dispersing agent, and the nickel oxide film which is compact, uniform, free of pinholes and high in crystallinity can be formed in a large-size range.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and in particular relates to a uniformly dispersed nickel oxide film and a preparation method and application thereof. Background Art

[0002] Commercially available nickel oxide nanocrystals have good dispersibility in water and are often used for small-area spin coating. They have the advantages of low cost and good hole transport performance. However, their aqueous solutions will gradually agglomerate in a short period of time, resulting in poor interface contact. Therefore, they are only widely used in small-area preparation.

[0003] In the prior art, polymers are used as dispersants for nickel oxide solutions, but long-chain ligands in the solution will remain in the nickel oxide film, hindering the effective extraction of charges, and ultimately leading to a decrease in the current and efficiency of the solar cell. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a uniformly dispersed nickel oxide film and a preparation method and application thereof, wherein a nickel oxide dispersion with good dispersion and stability is obtained by adopting a water-alcohol miscibility and adding an ionic dispersant, which is conducive to the formation of a dense, uniform, pinhole-free, and highly crystalline nickel oxide film in a large size range.

[0005] The present invention provides the following technical solutions: In a first aspect, a method for preparing a uniformly dispersed nickel oxide film is provided, comprising the following steps: Dispersing nickel oxide nanocrystals in water, adding an alcohol solvent, and subjecting the mixture to ultrasonic treatment to obtain a first dispersion; adding an ionic dispersant to the first dispersion, performing ultrasonic treatment and filtering to obtain a second dispersion; The second dispersion is coated on a conductive substrate, and after drying, annealing and UV treatment, a nickel oxide film is obtained.

[0006] Furthermore, the alcohol solvent includes one or more of methanol, ethanol, and tert-butanol.

[0007] Furthermore, the volume ratio of water to alcohol solvent in the first dispersion is 3:1 to 1:5. The amount of alcohol solvent added can improve the wettability of the dispersion with the substrate and can also accelerate the evaporation rate of the solvent. By adjusting the amount of alcohol solvent added, the concentration of the nickel oxide dispersion can be controlled to obtain nickel oxide films of different thicknesses.

[0008] Furthermore, the nickel oxide nanocrystals are dispersed in water and then ultrasonically treated for 5 to 10 minutes to obtain a nickel oxide aqueous dispersion.

[0009] Furthermore, after adding an alcohol solvent to the aqueous dispersion of nickel oxide, ultrasonic treatment is performed for 5 to 10 minutes.

[0010] Furthermore, the ionic dispersant is a short-chain quaternary ammonium salt, including one of dodecyl dimethyl ammonium chloride and bisdecyl dimethyl ammonium chloride.

[0011] Furthermore, the proportion of the ionic dispersant added to the first dispersion is 2 wt % to 5 wt %.

[0012] Furthermore, after the ionic dispersant is added to the first dispersion, ultrasonic treatment is performed for 25 to 35 minutes.

[0013] Furthermore, the filtering method includes: filtering using a 0.22 μm PTFE filter membrane.

[0014] Furthermore, the coating method of the first dispersion liquid includes one of spin coating, blade coating, and slit coating.

[0015] Furthermore, the drying is performed by spin drying or air gun drying.

[0016] Furthermore, the annealing temperature is 120° C. and the annealing time is 15 min. The annealing treatment can remove the residual ionic dispersant and improve the performance of the nickel oxide film.

[0017] Furthermore, the UV treatment time is 5 to 15 minutes. The UV treatment can reduce the series resistance, improve the effective extraction efficiency of the charge, and help improve the carrier transport capacity of the nickel oxide film when it is used as a hole transport layer.

[0018] Furthermore, the conductive substrate uses rigid ITO / FTO or flexible ITO / FTO. After cutting, etching and rinsing, the conductive substrate is ultrasonically cleaned with deionized water, ethanol and isopropanol for 15 minutes respectively, and then dried at 100°C, and treated with UV ozone for 30 minutes before preparing the nickel oxide film.

[0019] In a second aspect, a uniformly dispersed nickel oxide film is provided, which is prepared by the method described in the first aspect.

[0020] In a third aspect, a method for applying the uniformly dispersed nickel oxide thin film according to the second aspect in a perovskite solar cell is provided.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention prepares the nickel oxide thin film by dissolving nickel oxide nanocrystals in water and alcohol and adding an ionic dispersant. On the one hand, the hydrogen bond network inside the water can be destroyed, the surface tension of the nickel oxide dispersion can be reduced, and thus the wettability of the dispersion with a substrate can be improved; on the other hand, the ionic dispersant can be adsorbed on the surface of the nickel oxide nanoparticles to form a charge layer, which changes the surface energy and orientation of the particles, and not only inhibits the secondary agglomeration of the nickel oxide nanoparticles in the dispersion process, so that the dispersion remains agglomeration-free for more than 24 hours, but also forms a micro-network structure to form a stable nickel oxide dispersion; therefore, when preparing the nickel oxide thin film, the nickel oxide nanocrystals can be well adhered to the surface of the conductive substrate when coated over a large area, which is conducive to forming a dense, uniform, pinhole-free, and highly crystallinity nickel oxide thin film in a large size range, and when the nickel oxide thin film prepared by the method of the present invention is used as a hole transport layer of a perovskite solar cell, the stability of the solar cell can be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the process of preparing a nickel oxide thin film according to an embodiment of the present invention; Figure 2 1 is a current density-voltage characteristic curve of the perovskite solar cell in Example 1 of the present invention and Comparative Example 1; Figure 3 1 is a current density-voltage characteristic curve of the perovskite solar cell in Examples 2 to 4 of the present invention and Comparative Example 2. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0024] Example 1

[0025] This embodiment provides a method for preparing a nickel oxide thin film. The preparation process is as follows: Figure 1 As shown, the specific steps are: Take a 2*2cm rigid ITO, etch away the ITO 5mm above with hydrochloric acid and Zn powder, ultrasonically clean it with deionized water, ethanol and isopropanol for 15 minutes, then dry it at 100℃, cool it naturally and set it aside for use. Treat the surface with UV ozone for 30 minutes before use.

[0026] 40 mg of nickel oxide nanocrystals were dispersed in 1 mL of deionized water, and 1 mL of ethanol was added after ultrasonic treatment for 5 min. The mixture was ultrasonicated again for 5 min to be evenly mixed, thereby obtaining a first dispersion.

[0027] A dispersant of bis(chlorobenzene)dimethylammonium chloride accounting for 2 wt % of the first dispersion was added to the first dispersion, and a stable nickel oxide dispersion was prepared after ultrasonic treatment for 30 minutes.

[0028] The nickel oxide dispersion was filtered through a 0.22 μm PTFE filter membrane and then coated on the surface of the rigid ITO substrate by spin coating. The remaining solution on the surface was dried with an air gun, and annealed on a hot stage at 120° C. for 15 min. After cooling, the nickel oxide film was treated with UV for 10 min.

[0029] The obtained nickel oxide film was used as a hole transport layer to prepare an inverted perovskite solar cell, and the performance of the obtained perovskite solar cell was tested.

[0030] Example 2

[0031] This embodiment provides a method for preparing a nickel oxide thin film, which is suitable for large-area preparation of a hole transport layer. The specific steps are: After PI etching, the 5*5cm flexible ITO substrate was ultrasonically cleaned with deionized water, ethanol and isopropanol for 15 minutes, then dried at 100°C and naturally cooled for use. The surface was treated with UV ozone for 30 minutes before use.

[0032] 100 mg of nickel oxide nanocrystals were dispersed in 60 mL of deionized water, and after ultrasonication for 5 min, 40 mL of tert-butanol was added, and ultrasonication was performed again for 5 min to mix evenly, thereby obtaining a first dispersion.

[0033] A dispersant of bis(chlorobenzene)dimethylammonium chloride accounting for 2 wt % of the first dispersion was added to the first dispersion, and a stable nickel oxide dispersion was prepared after ultrasonic treatment for 30 minutes.

[0034] The nickel oxide dispersion was filtered through a 0.22 μm PTFE filter membrane and then coated on the surface of the flexible ITO substrate by a slit coating method. The liquid film was then blown dry by an air knife and annealed on a hot plate at 120° C. for 15 min. After cooling, the nickel oxide film was treated with UV for 15 min.

[0035] The obtained nickel oxide film was used as a hole transport layer to prepare an inverted perovskite solar cell, and the performance of the obtained perovskite solar cell was tested.

[0036] Example 3

[0037] This embodiment provides a method for preparing a nickel oxide thin film. The difference from Embodiment 2 is that dodecyl dimethyl ammonium chloride is used as a dispersant to prepare a 5*5 cm module. The specific steps are as follows: After PI etching, the 5*5cm flexible ITO substrate was ultrasonically cleaned with deionized water, ethanol and isopropanol for 15 minutes, then dried at 100°C and naturally cooled for use. The surface was treated with UV ozone for 30 minutes before use.

[0038] 100 mg of nickel oxide nanocrystals were dispersed in 60 mL of deionized water, and after ultrasonication for 5 min, 40 mL of tert-butanol was added, and ultrasonication was performed again for 5 min to mix evenly, thereby obtaining a first dispersion.

[0039] 2 wt % of dodecyl dimethyl ammonium chloride in the first dispersion was added to the first dispersion, and then ultrasonicated for 30 minutes to prepare a stable nickel oxide dispersion.

[0040] The nickel oxide dispersion was filtered through a 0.22 μm PTFE filter membrane and then coated on the surface of the flexible ITO substrate by a slit coating method. The liquid film was then blown dry by an air knife and annealed on a hot plate at 120° C. for 15 min. After cooling, the nickel oxide film was treated with UV for 15 min.

[0041] The obtained nickel oxide film was used as a hole transport layer to prepare an inverted perovskite solar cell, and the performance of the obtained perovskite solar cell was tested.

[0042] Example 4

[0043] This embodiment provides a method for preparing a nickel oxide thin film. The difference from the embodiment 3 is that the proportion of the dispersant is adjusted to prepare a 5*5 cm module. The specific steps are as follows: After PI etching, the 5*5cm flexible ITO substrate was ultrasonically cleaned with deionized water, ethanol and isopropanol for 15 minutes, then dried at 100°C and naturally cooled for use. The surface was treated with UV ozone for 30 minutes before use.

[0044] 100 mg of nickel oxide nanocrystals were dispersed in 60 mL of deionized water, and after ultrasonication for 5 min, 40 mL of tert-butanol was added, and ultrasonication was performed again for 5 min to mix evenly, thereby obtaining a first dispersion.

[0045] 3 wt % of dodecyl dimethyl ammonium chloride in the first dispersion was added to the first dispersion, and then ultrasonicated for 30 minutes to prepare a stable nickel oxide dispersion.

[0046] The nickel oxide dispersion was filtered through a 0.22 μm PTFE filter membrane and then coated on the surface of the flexible ITO substrate by a slit coating method. The liquid film was then blown dry by an air knife and annealed on a hot plate at 120° C. for 15 min. After cooling, the nickel oxide film was treated with UV for 15 min.

[0047] The obtained nickel oxide film was used as a hole transport layer to prepare an inverted perovskite solar cell, and the performance of the obtained perovskite solar cell was tested.

[0048] Comparative Example 1 In this comparative example, nickel oxide powder is directly used to obtain a small-area oxide film by spin coating, and the specific steps are as follows: After etching, a 2*2 cm rigid ITO substrate was ultrasonically cleaned with deionized water, ethanol and isopropanol for 15 min, then dried at 100° C. and naturally cooled for use. The surface was treated with UV ozone for 30 min before use.

[0049] Nickel oxide powder was dispersed in deionized water at a concentration of 20 mg / mL, and after filtering, a nickel oxide film was prepared by spin coating and annealing.

[0050] The obtained nickel oxide film was used as a hole transport layer to prepare an inverted perovskite solar cell, and the performance of the obtained perovskite solar cell was tested.

[0051] Comparative Example 2 In this comparative example, conventional nickel oxide aqueous dispersion was used to prepare a large-area nickel oxide thin film by a slit coating method, and the specific steps were as follows: After the 5*5cm flexible ITO substrate was etched by P1, it was ultrasonically cleaned with deionized water, ethanol and isopropanol for 15 minutes, then dried at 100°C and naturally cooled for use. The surface was treated with UV ozone for 30 minutes before use.

[0052] Nickel oxide nanocrystals were dispersed in deionized water at a concentration of 10 mg / mL, filtered, and then formed into a nickel oxide liquid film by a slit coating method. The liquid film was dried by an air knife and annealed on a hot stage at 120°C for 15 min to obtain a nickel oxide thin film.

[0053] The obtained nickel oxide film was used as a hole transport layer to prepare an inverted perovskite solar cell, and the performance of the obtained perovskite solar cell was tested.

[0054] Performance comparison (1) Figure 2 is a current density-voltage characteristic curve of the perovskite solar cell in Example 1 and Comparative Example 1, Figure 3 2 is a graph showing the current density-voltage characteristic of the perovskite solar cell in Examples 2 to 4 and Comparative Example 2. Figure 2 It can be seen that for small-area devices, there is no significant difference in the performance of nickel oxide films with and without ionic dispersants. Figure 3 It can be seen that after the device size is enlarged, the performance of the nickel oxide film with and without the addition of ionic dispersant is significantly different, so the preparation method of the present invention is more suitable for the enlarged preparation of nickel oxide process.

[0055] (2) The performance test results of the perovskite solar cells in Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Table 1 below: Table 1 Performance test results of perovskite solar cells in Examples 1 to 4 and Comparative Examples 1 to 2

[0056] As can be seen from Table 1, compared with Examples 1 to 4 and Comparative Examples 1 to 2, for devices of the same size, the nickel oxide film prepared by the embodiments of the present invention is more uniform and dense, and can achieve a better filling factor; compared with Example 2 and Example 3, the change in the type of ionic dispersant has little effect on the performance of the nickel oxide film; compared with Example 3, Example 4 increases the concentration of the ionic dispersant, so that the prepared nickel oxide film is more uniform and dense, thereby achieving a better filling factor.

[0057] 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 technical principles 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 uniformly dispersed nickel oxide film, characterized in that: The following steps are involved: Dispersing nickel oxide nanocrystals in water, adding an alcohol solvent, and subjecting the mixture to ultrasonic treatment to obtain a first dispersion; adding an ionic dispersant to the first dispersion, performing ultrasonic treatment and filtering to obtain a second dispersion; The second dispersion is coated on a conductive substrate, and after drying, annealing and UV treatment, a nickel oxide film is obtained.

2. The method for preparing a uniformly dispersed nickel oxide thin film according to claim 1, characterized in that: The alcohol solvent includes one or more of methanol, ethanol and tert-butanol.

3. The method for preparing a uniformly dispersed nickel oxide thin film according to claim 1, characterized in that: The volume ratio of water to alcohol solvent in the first dispersion is 3:1 to 1:

5.

4. The method for preparing a uniformly dispersed nickel oxide thin film according to claim 1, characterized in that: The ionic dispersant is a short-chain quaternary ammonium salt, including one of dodecyl dimethyl ammonium chloride and bisdecyl dimethyl ammonium chloride.

5. The method for preparing a uniformly dispersed nickel oxide thin film according to claim 1, characterized in that: The proportion of the ionic dispersant added to the first dispersion is 2 wt % to 5 wt %.

6. The method for preparing a uniformly dispersed nickel oxide thin film according to claim 1, characterized in that: The filtering method comprises: filtering with a 0.22 μm PTFE filter membrane.

7. The method for preparing a uniformly dispersed nickel oxide thin film according to claim 1, characterized in that: The annealing temperature is 120° C. and the annealing time is 15 min.

8. The method for preparing a uniformly dispersed nickel oxide thin film according to claim 1, characterized in that: The UV treatment time is 5 to 15 minutes.

9. A uniformly dispersed nickel oxide film, characterized in that: The method is prepared by any one of claims 1 to 8.

10. Use of the uniformly dispersed nickel oxide film according to claim 9 in a perovskite solar cell.

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