Hole transport layer, perovskite solar cell and preparation method thereof

Abstract

The invention relates to a hole transport layer, a perovskite solar cell and a preparation method thereof. The hole transport layer comprises carbon-coated nickel oxide nanoparticles. The hole transport layer provided by the invention comprises the carbon-coated nickel oxide nanoparticles, and a carbon shell layer is constructed on the surface of the nickel oxide to obtain the carbon-coated nickel oxide material, so that on one hand, the surface defects of the nickel oxide can be effectively inhibited, and the conductivity of the nickel oxide material is improved; and on the other hand, the carbon-coated nickel oxide material can effectively inhibit the photocatalytic performance of nickel oxide, so that the degradation reaction at the bottom of the perovskite is prevented, and compared with a pure nickel oxide material serving as the hole transport layer, the ultraviolet stability of the perovskite solar cell can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a hole transport layer, a perovskite solar cell and a preparation method thereof. Background Art

[0002] Organic-inorganic hybrid perovskite solar cells have attracted extensive attention in the academic and industrial fields due to many advantages such as adjustable bandgap and low cost. At present, the highest power conversion efficiency of single-junction perovskite solar cells has exceeded 26%, showing excellent commercialization prospects. In addition to the power conversion efficiency, the stability of perovskite solar cells is also crucial and is the entry threshold for their commercialization process. Traditional perovskite solar cells mainly have three structures, namely mesoporous structure, planar heterojunction structure, and inverted structure. Regardless of which structure, they usually consist of a hole transport layer (ETL), a perovskite light absorption layer, an electron transport layer (HTL), electrode materials, etc. NiO x As a common hole transport layer material, it can be well compatible with processes such as dry process (PVD sputtering) and wet coating (nanoparticles). In addition, the transition metal oxide NiO x also has significant photocatalytic properties, which greatly affect the stability of perovskite solar cells, especially the ultraviolet stability.

[0003] The prior art CN118555884A discloses a method for optimizing the NiO x / SAM hole transport layer, which realizes the uniform and robust anchoring of SAM molecules through the improvement of the NiO x film surface, thereby promoting charge extraction and suppressing interfacial non-radiative recombination. It mainly improves the surface properties of the NiO x film by performing plasma treatment in an oxygen atmosphere (O2-plasma) on the NiO x film surface; the O2-plasma treatment increases the conductivity of NiO x and promotes hole extraction from perovskite to NiO x / SAM; SAM molecules form a uniform, dense and firm monolayer on the surface of the O2-plasma-treated NiO x surface, realizing high-quality perovskite films and efficient charge extraction. However, it does not pay attention to stability, especially ultraviolet stability, and the preparation process of this method is complex and the manufacturing cost is relatively high.

[0004] Therefore, how to suppress the photocatalytic properties of nickel oxide and provide a UV-stable hole transport layer and its preparation method to improve the UV stability of perovskite solar cells has become an urgent problem to be solved at present. Summary of the Invention

[0005] To solve the above technical problems, the object of the present invention is to provide a hole transport layer, a preparation method thereof, and a perovskite solar cell. The hole transport layer provided by the present invention includes carbon-coated nickel oxide nanoparticles, which can effectively improve the ultraviolet stability of perovskite solar cells.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a hole transport layer, and the hole transport layer includes carbon-coated nickel oxide nanoparticles.

[0008] The hole transport layer provided by the present invention includes carbon-coated nickel oxide nanoparticles. A carbon shell layer is constructed on the surface of nickel oxide to obtain a carbon-coated nickel oxide material. On the one hand, it can effectively inhibit the surface defects of nickel oxide and improve the conductivity of the nickel oxide material; on the other hand, the carbon-coated nickel oxide material can effectively inhibit the photocatalytic performance of nickel oxide as a hole transport layer, thereby preventing the degradation reaction occurring at the bottom of the perovskite in close contact with it. Compared with the pure nickel oxide material, the carbon-coated nickel oxide material as a hole transport layer can greatly improve the ultraviolet stability of perovskite solar cells.

[0009] The following are the preferred technical solutions of the present invention, but not the limitations on the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0010] In a second aspect, the present invention provides a preparation method of the hole transport layer as described in the first aspect, and the preparation method of the hole transport layer includes the following steps:

[0011] Mix nickel oxide nanoparticles with an organic carbon source to obtain a reaction slurry, and obtain carbon-coated nickel oxide nanoparticles through a hydrothermal reaction;

[0012] The carbon-coated nickel oxide nanoparticles are coated to obtain a hole transport layer.

[0013] The present invention synthesizes carbon-coated nickel oxide nanoparticles through a simple hydrothermal reaction and obtains a hole transport layer through coating, without high-temperature calcination, with a simple process and low cost, and has broad application prospects.

[0014] The organic carbon source includes a benzene ring and / or a pyridine structure; the organic carbon source has an amino and / or a carboxyl substituent.

[0015] Preferably, the organic carbon source includes any one or a combination of at least two of o-phenylenediamine, o-phenylenediamine derivatives, m-phenylenediamine, m-phenylenediamine derivatives, p-phenylenediamine, p-phenylenediamine derivatives, phthalic acid, phthalic acid derivatives, isophthalic acid, isophthalic acid derivatives, terephthalic acid, terephthalic acid derivatives, trimellitic acid, 3-aminopyridine-2-carboxylic acid or 4-aminopyridine-3-carboxylic acid. Typical but non-limiting combinations include the combination of o-phenylenediamine and p-phenylenediamine, the combination of phthalic acid and isophthalic acid, the combination of o-phenylenediamine and terephthalic acid, the combination of p-phenylenediamine derivatives and terephthalic acid, the combination of 3-aminopyridine-2-carboxylic acid and 4-aminopyridine-3-carboxylic acid, the combination of trimellitic acid and 3-aminopyridine-2-carboxylic acid, or the combination of trimellitic acid, 3-aminopyridine-2-carboxylic acid and 4-aminopyridine-3-carboxylic acid.

[0016] The organic carbon source used in the present invention includes a benzene ring and / or a pyridine structure; the organic carbon source has an amino and / or carboxyl substituent, which is more likely to form a coating layer on the surface of nickel oxide nanoparticles. Subsequently, no calcination is required to form a carbon coating layer. In the conventional coating method, non-conjugated structure organic substances such as citric acid or glucose are used, and a high-temperature calcination step is required in the subsequent process to form a carbon coating layer.

[0017] Preferably, the mass ratio of the nickel oxide nanoparticles to the organic carbon source is 1:(0.3 - 0.5). For example, it can be 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0018] By further controlling the mass ratio of the nickel oxide nanoparticles to the organic carbon source to be 1:(0.3 - 0.5), within this mass ratio range, nickel oxide nanoparticles with a complete carbon coating layer can be obtained, thereby effectively suppressing the defects of nickel oxide, improving the conductivity of nickel oxide while suppressing the photocatalytic performance of nickel oxide. If the addition amount of the organic carbon source is too much, the carbon coating layer will be too thick, affecting the work function of nickel oxide, and further causing a decrease in the open-circuit voltage of the corresponding perovskite battery; if the addition amount of the organic carbon source is too little, the degree of carbon coating will be too low to effectively suppress the photocatalytic performance of nickel oxide nanoparticles.

[0019] Preferably, in the reaction slurry, the concentration of the nickel oxide nanoparticles is 10mg / mL - 50mg / mL. For example, it can be 10mg / mL, 15mg / mL, 20mg / mL, 25mg / mL, 30mg / mL, 35mg / mL, 40mg / mL, 45mg / mL or 50mg / mL, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0020] Preferably, the temperature of the hydrothermal reaction is 150°C - 220°C. For example, it can be 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C or 220°C. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0021] Preferably, the time of the hydrothermal reaction is 1h - 5h. For example, it can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0022] In the present invention, hydrothermal method is used to prepare carbon-coated nickel oxide nanoparticles. Under hydrothermal conditions, the activity of the hydroxyl groups on the surface of metal oxides is improved, the particles have good dispersibility, high reaction activity and more uniform reaction. And nickel oxide can react with alcohol solvents, so solvent method is not adopted in the present invention.

[0023] Preferably, the temperature of the annealing is 100°C - 150°C. For example, it can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0024] Preferably, the time of the annealing is 5min - 30min. For example, it can be 5min, 10min, 15min, 20min, 25min or 30min. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0025] Preferably, the average particle size of the carbon-coated nickel oxide nanoparticles is 1nm - 10nm. For example, it can be 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm or 10nm. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0026] In the present invention, by further controlling the average particle size of the carbon-coated nickel oxide nanoparticles to be 1nm - 10nm, small-sized nanoparticles are more conducive to improving the film-forming uniformity, can effectively reduce the defects of the tin oxide functional layer. If the average size of the carbon-coated nickel oxide nanoparticles is too large, the density of the hole transport layer decreases and the defects increase, resulting in a decrease in the performance of the corresponding perovskite solar cells.

[0027] Preferably, before the coating, washing and dispersing the carbon-coated nickel oxide nanoparticles are also included.

[0028] Preferably, the solvent used for washing includes water and / or ethanol.

[0029] Preferably, the dispersion method includes ultrasonic dispersion in water.

[0030] Preferably, the concentration of the obtained dispersion liquid is 10mg / mL - 20mg / mL. For example, it can be 10mg / mL, 11mg / mL, 12mg / mL, 13mg / mL, 14mg / mL, 15mg / mL, 16mg / mL, 17mg / mL, 18mg / mL, 19mg / mL or 20mg / mL, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0031] As a preferred technical solution of the preparation method of the present invention, the preparation method includes the following steps:

[0032] Mix nickel oxide nanoparticles and an organic carbon source according to a mass ratio of 1:(0.3 - 0.5) to obtain a reaction slurry with a concentration of nickel oxide nanoparticles of 10mg / mL - 50mg / mL. The reaction slurry is hydrothermally reacted at 150°C - 220°C for 1h - 5h to obtain carbon-coated nickel oxide nanoparticles with an average particle size of 1nm - 10nm; after the carbon-coated nickel oxide nanoparticles are washed with water and / or ethanol, they are ultrasonically dispersed in water to obtain a dispersion liquid with a mass concentration of 10mg / mL - 20mg / mL. The slurry is coated to obtain a hole transport layer with a thickness of 10nm - 300nm;

[0033] The organic carbon source includes any one or a combination of at least two of o-, m-, p-phenylenediamine and its derivatives, o-, m-, p-phthalic acid and its derivatives, trimesic acid, 3-aminopyridine-2-carboxylic acid or 4-aminopyridine-3-carboxylic acid.

[0034] In the third aspect, the present invention provides a perovskite solar cell, which includes the hole transport layer described in the first aspect.

[0035] The perovskite solar cell provided by the present invention is an inverted perovskite solar cell, which has excellent photoelectric conversion efficiency and ultraviolet stability, has excellent conductivity, can maintain the perovskite from degrading under long-term ultraviolet light irradiation, and significantly improves the service life of the perovskite solar cell.

[0036] Preferably, the structure of the perovskite solar cell includes a transparent conductive layer, a hole transport layer, a perovskite absorption layer, an electron transport layer and an electrode arranged in sequence.

[0037] Preferably, the thickness of the hole transport layer is 10 nm - 300 nm. For example, it can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 80 nm, 100 nm, 200 nm, 300 nm, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0038] Preferably, the material of the transparent conductive layer includes any one or a combination of at least two of FTO (fluorine-doped tin oxide conductive glass), ITO (indium tin oxide conductive glass), IZO (indium zinc oxide conductive glass), IWO (indium tungsten oxide conductive glass), or AZO (aluminum-doped zinc oxide).

[0039] Preferably, the material of the perovskite absorption layer includes MA 0.05 Cs 0.05 FA 0.9 Pb(I 0.95 Br 0.05 )3, CH3NH3PbI3, CsPbI3, FAPbI3, or CsPbI2Br, or a combination of any one or at least two of them.

[0040] Preferably, the material of the electron transport layer includes any one or a combination of at least two of C60, PC 61 BM, PC 71 BM, ICBA, Y6, BCP, or tin oxide.

[0041] Preferably, the electrode includes any one or a combination of at least two of Cu, Au, Ag, or Al.

[0042] Fourthly, the present invention provides a method for preparing a perovskite solar cell as described in the third aspect. The preparation method includes the following steps:

[0043] (1) The hole transport layer as described in claim 1 is disposed on the surface of the transparent conductive layer;

[0044] (2) The perovskite absorption layer is disposed on the surface of the hole transport layer away from the transparent conductive layer;

[0045] (3) The electron transport layer is disposed on the surface of the perovskite absorption layer away from the electron layer;

[0046] (4) The electrode is disposed on the surface of the electron transport layer away from the perovskite absorption layer.

[0047] In the method for preparing the perovskite solar cell described in the present invention, except for the hole transport layer, the other layers can be prepared by the conventional method for preparing a perovskite solar cell without special requirements.

[0048] The numerical ranges described in the present invention include not only the above-listed point values, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the described ranges.

[0049] Compared with the prior art, the present invention has at least the following beneficial effects:

[0050] The hole transport layer provided by the present invention comprises carbon-coated nickel oxide nanoparticles. A carbon shell layer is constructed on the surface of nickel oxide, and the obtained carbon-coated nickel oxide material can, on the one hand, effectively suppress the surface defects of nickel oxide and improve the conductivity of the nickel oxide material; on the other hand, the carbon-coated nickel oxide material can effectively inhibit the photocatalytic performance of nickel oxide, thereby preventing the degradation reaction occurring at the bottom of the perovskite. Compared with the pure nickel oxide material used as the hole transport layer, the ultraviolet stability of the perovskite solar cell can be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 FIG. 1 is a schematic structural diagram of a perovskite solar cell with carbon-coated nickel oxide nanoparticles prepared in Application Example 1 of the present invention. Among them, 1 is an FTO glass substrate, 2 is a nickel oxide hole transport layer, 3 is a perovskite absorption layer, 4 is a C60 / SnO2 composite electron transport layer, and 5 is a Cu electrode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0052] The technical solutions of the present invention will be further described below with reference to the drawings and through specific embodiments. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0053] In the following examples and comparative examples, unless otherwise specified, all reagents and consumables are purchased from conventional reagent manufacturers in the art; unless otherwise specified, the experimental methods and technical means used are conventional methods and means in the art.

[0054] Example 1

[0055] This example provides a hole transport layer, and the preparation method of the hole transport layer comprises the following steps:

[0056] Nickel oxide nanoparticles and phthalic acid are mixed in a mass ratio of 1:0.5 to obtain a reaction slurry with a concentration of nickel oxide nanoparticles of 50 mg / mL. The reaction slurry is hydrothermally reacted at 170 °C for 3 h to obtain carbon-coated nickel oxide nanoparticles with an average particle size of 10 nm; after the carbon-coated nickel oxide nanoparticles are washed with water and / or ethanol, they are ultrasonically dispersed in water to obtain a slurry with a mass concentration of 20 mg / mL. The slurry is coated to obtain a hole transport layer with a thickness of 260 nm.

[0057] Example 2

[0058] This example provides a hole transport layer. The preparation method of the hole transport layer includes the following steps:

[0059] Mix nickel oxide nanoparticles and p-phenylenediamine according to a mass ratio of 1:0.3 to obtain a reaction slurry with a concentration of nickel oxide nanoparticles of 30 mg / mL. The reaction slurry is hydrothermally reacted at 160 °C for 5 h to obtain carbon-coated nickel oxide nanoparticles with an average particle size of 6 nm. After the carbon-coated nickel oxide nanoparticles are washed with water and / or ethanol, they are ultrasonically dispersed in water to obtain a slurry with a mass concentration of 15 mg / mL. The slurry is coated to obtain a hole transport layer with a thickness of 170 nm.

[0060] Example 3

[0061] This example provides a hole transport layer. The preparation method of the hole transport layer includes the following steps:

[0062] Mix nickel oxide nanoparticles with 3-aminopyridine-2-carboxylic acid and 4-aminopyridine-3-carboxylic acid (the mass ratio of 3-aminopyridine-2-carboxylic acid and 4-aminopyridine-3-carboxylic acid is 1:1) according to a mass ratio of 1:0.4 to obtain a reaction slurry with a concentration of nickel oxide nanoparticles of 20 mg / mL. The reaction slurry is hydrothermally reacted at 210 °C for 1 h to obtain carbon-coated nickel oxide nanoparticles with an average particle size of 6 nm. After the carbon-coated nickel oxide nanoparticles are washed with water and / or ethanol, they are ultrasonically dispersed in water to obtain a slurry with a mass concentration of 10 mg / mL. The slurry is coated to obtain a hole transport layer with a thickness of 80 nm.

[0063] Example 4

[0064] This example provides a hole transport layer. The difference from Example 1 is only that when preparing this hole transport layer, the mass ratio of nickel oxide nanoparticles to phthalic acid is 1:0.1.

[0065] Example 5

[0066] This example provides a hole transport layer. The difference from Example 1 is only that when preparing this hole transport layer, the mass ratio of nickel oxide nanoparticles to phthalic acid is 1:1.

[0067] Example 6

[0068] This example provides a hole transport layer. The difference from Example 1 is only that when preparing this hole transport layer, the average size of the carbon-coated nickel oxide nanoparticles is 15 nm.

[0069] Comparative Example 1

[0070] This comparative example provides a hole transport layer, which is only different from that of Example 1 in that the hole transport layer is nickel oxide nanoparticles without carbon coating, and the nickel oxide nanoparticles are directly dispersed and coated to obtain the hole transport layer.

[0071] Application Example 1

[0072] This application example provides a perovskite solar cell and a preparation method thereof. The preparation method includes the following steps:

[0073] (1) Spin-coat the hole transport layer as described in Example 1 on the surface of the FTO glass substrate, and anneal the FTO glass at 130 °C for 20 min;

[0074] (2) Spin-coat the perovskite absorption layer MA 0.05 Cs 0.05 FA 0.9 Pb(I 0.95 Br 0.05 )3 on the surface of the hole transport layer away from the FTO;

[0075] Among them, the structural composition of the perovskite precursor solution is: MA 0.05 Cs 0.05 FA 0.9 Pb(I 0.95 Br 0.05 )3. The specific formulations of each component are: CsI (19.5 mg); MABr (8.4 mg); FAI (219.5 mg); PbI2 (659.5 mg); PbBr2 (27.5 mg); Add an appropriate amount of 2-ME, DMF, and DMSO to the weighed drug powder (the more specific solvent ratio is 2-ME:DMF:DMSO = 8:1:1), configure it into a perovskite solution with a concentration of 1.0 M, and place it on a heating and stirring table, stir at room temperature for 4 h to fully dissolve it; Spin-coat the above perovskite precursor mixture on the FTO glass substrate through a slot coating device to prepare a uniform perovskite solution wet film, and dry it at 100 °C in a vacuum drying device for 20 min, and then anneal and crystallize it in a tunnel furnace to obtain the perovskite absorption layer.

[0076] (3) Deposit the electron transport layers C60 and SnO2 on the surface of the perovskite absorption layer away from the electron layer.

[0077] (4) Spin-coat the electrode Cu on the surface of the electron transport layers C60 and SnO2 away from the perovskite absorption layer.

[0078] The structural schematic diagram of the prepared perovskite solar cell is as Figure 1 shown, from Figure 1As can be seen from [Figure 0], 1 is an FTO glass substrate, 2 is a nickel oxide hole transport layer, 3 is a perovskite functional layer, 4 is a C60 / SnO2 composite electron transport layer, and 5 is a Cu electrode.

[0079] Application Example 2 - Application Example 6

[0080] This application example provides a perovskite solar cell. The difference between the preparation method of the perovskite solar cell and that of Application Example 1 is only that: in step (1), a hole transport layer as described in Examples 2 - 6 is respectively provided on the surface of the transparent conductive layer, and other steps remain unchanged.

[0081] Application Example 7

[0082] This application example provides a perovskite solar cell. The difference between the preparation method of the perovskite solar cell and that of Application Example 1 is that: in step (1), the transparent conductive layer is AZO, in step (2), the perovskite absorption layer is CsPbI2Br, in step (3), the electron transport layer is PC 61 BM, and in step (4), the electrode is Al, and other steps remain unchanged.

[0083] Comparative Application Example 1

[0084] This comparative application example provides a perovskite solar cell. The difference between the preparation method of the perovskite solar cell and that of Application Example 1 is only that: in step (1), a hole transport layer as described in Comparative Example 1 is respectively provided on the surface of the transparent conductive layer, and other steps remain unchanged.

[0085] Comparative Application Example 2

[0086] This comparative application example provides a perovskite solar cell. The difference between the preparation method of the perovskite solar cell and that of Application Example 7 is only that: in step (1), a hole transport layer as described in Comparative Example 1 is respectively provided on the surface of the transparent conductive layer, and other steps remain unchanged.

[0087] Test method: For the perovskite solar cells prepared in the application examples and comparative application examples, under the conditions of different ultraviolet irradiation amounts, the photoelectric conversion efficiency (PCE) test is carried out, and the test results are shown in Table 1 below.

[0088] Table 1

[0089] 0 kW·h 2 kW·h 4 kW·h 6 kW·h 8 kW·h Application Example 1 17.22％ 17.39％ 17.04％ 16.54％ 16.23％ Application Example 2 17.43％ 17.17％ 16.75％ 16.49％ 16.13％ Application Example 3 17.36％ 17.13％ 16.92％ 16.74％ 16.47％ Application Example 4 17.25％ 16.13％ 14.65％ 10.17％ 6.32％ Application Example 5 14.32％ 13.17％ 12.43％ 11.87％ 10.72％ Application Example 6 15.32％ 14.71％ 14.09％ 13.28％ 11.52％ Application Example 7 15.31％ 14.79％ 14.38％ 14.01％ 13.73％ Comparative Application Example 1 17.03％ 15.32％ 14.11％ 9.87％ 4.94％ Comparative Application Example 2 15.47％ 13.20％ 10.91％ 6.35％ 3.07％

[0090] It can be seen from the test results that:

[0091] (1) As can be seen from Application Examples 1 - 3, the hole transport layer provided by the present invention includes carbon-coated nickel oxide nanoparticles. A carbon shell layer is constructed on the surface of nickel oxide to obtain the carbon-coated nickel oxide material. On the one hand, it can effectively inhibit the surface defects of nickel oxide and improve the conductivity of the nickel oxide material; on the other hand, the carbon-coated nickel oxide material can effectively inhibit the photocatalytic performance of nickel oxide, thereby preventing the degradation reaction occurring at the bottom of the perovskite. Compared with using pure nickel oxide material as the hole transport layer, it can greatly improve the ultraviolet stability of the perovskite solar cell and significantly extend the service life of the perovskite solar cell.

[0092] (2) As can be seen from the comparison between Application Example 1 and Application Examples 4 - 5, by further controlling the mass ratio of nickel oxide nanoparticles to the organic carbon source in the present invention to be 1:(0.3 - 0.5), within this mass ratio range, nickel oxide nanoparticles with a complete carbon coating layer can be obtained, thereby effectively inhibiting the defects of nickel oxide, improving the conductivity of nickel oxide while inhibiting the photocatalytic performance of nickel oxide, and obtaining a perovskite solar cell with excellent photoelectric conversion efficiency. If the addition amount of the organic carbon source is too much, it will cause the carbon coating layer to be too thick, affecting the work function of nickel oxide, and further resulting in a decrease in the open-circuit voltage of the corresponding perovskite cell; if the addition amount of the organic carbon source is too little, it will lead to a low degree of carbon coating and unable to effectively inhibit the photocatalytic performance of nickel oxide nanoparticles.

[0093] (3) As can be seen from the comparison between Application Example 1 and Application Example 6, by further controlling the average particle size of the carbon-coated nickel oxide nanoparticles to be 1 nm - 10 nm in the present invention, smaller-sized nanoparticles are more conducive to improving the film-forming uniformity and can effectively reduce the defects of the tin oxide functional layer. If the average size of the carbon-coated nickel oxide nanoparticles is too large, the density of the hole transport layer will decrease and the defects will increase, resulting in a decrease in the performance of the corresponding perovskite solar cell.

[0094] (4) As can be seen from the comparison between Application Example 1 and Comparative Application Example 1, when nickel oxide nanoparticles are used as the hole transport layer without carbon coating, under ultraviolet light irradiation, free hydroxyl radicals are easily generated on the surface of the nickel oxide nanoparticles. These active radicals attack the perovskite functional layer, causing a degradation reaction at the bottom of the perovskite, and further leading to a significant decrease in the photoelectric conversion efficiency of the perovskite solar cell.

[0095] (5) As can be seen from the comparison between Application Example 7 and Comparative Application Example 2, in the present invention, when other conventional components are selected for each layer of the perovskite solar cell except for the hole transport layer, the ultraviolet stability of the perovskite solar cell can also be improved.

[0096] In summary, the hole transport layer provided by the present invention includes carbon-coated nickel oxide nanoparticles. A carbon shell layer is constructed on the surface of nickel oxide to obtain a carbon-coated nickel oxide material. On the one hand, it can effectively suppress the surface defects of nickel oxide and improve the conductivity of the nickel oxide material; on the other hand, the carbon-coated nickel oxide material can effectively inhibit the photocatalytic performance of nickel oxide, thereby preventing the degradation reaction occurring at the bottom of the perovskite. Compared with the pure nickel oxide material used as the hole transport layer, it can greatly improve the ultraviolet stability of the perovskite solar cell and significantly extend the service life of the perovskite solar cell.

[0097] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A hole transport layer, characterized in that, The hole transport layer includes carbon-coated nickel oxide nanoparticles.

2. A method for preparing a hole transport layer as described in claim 1, characterized in that, The preparation method of the hole transport layer includes the following steps: Mix nickel oxide nanoparticles with an organic carbon source to obtain a reaction slurry, and obtain carbon-coated nickel oxide nanoparticles through a hydrothermal reaction; The carbon-coated nickel oxide nanoparticles are coated and annealed to obtain the hole transport layer.

3. The preparation method according to claim 2, characterized in that, The organic carbon source includes a benzene ring and / or a pyridine structure; the organic carbon source has an amino and / or carboxyl substituent; Preferably, the organic carbon source includes any one or a combination of at least two of o-phenylenediamine, o-phenylenediamine derivatives, m-phenylenediamine, m-phenylenediamine derivatives, p-phenylenediamine, p-phenylenediamine derivatives, phthalic acid, phthalic acid derivatives, isophthalic acid, isophthalic acid derivatives, terephthalic acid, terephthalic acid derivatives, trimesic acid, 3-aminopyridine-2-carboxylic acid, or 4-aminopyridine-3-carboxylic acid; Preferably, the mass ratio of the nickel oxide nanoparticles to the organic carbon source is 1:(0.3 - 0.5).

4. The preparation method according to claim 2 or 3, characterized in that, In the reaction slurry, the concentration of the nickel oxide nanoparticles is 10 mg / mL - 50 mg / mL; Preferably, the temperature of the hydrothermal reaction is 150°C - 220°C; Preferably, the time of the hydrothermal reaction is 1 h - 5 h; Preferably, the temperature of the annealing is 100°C - 150°C; Preferably, the time of the annealing is 5 min - 30 min.

5. The preparation method according to any one of claims 2-4, characterized in that, The average particle size of the carbon-coated nickel oxide nanoparticles is 1 nm - 10 nm.

6. The preparation method according to any one of claims 2-5, characterized in that, Before the coating, washing and dispersing the carbon-coated nickel oxide nanoparticles are also included; Preferably, the solvent used for washing includes water and / or ethanol; Preferably, the dispersing method includes ultrasonic dispersion in water; Preferably, the concentration of the dispersion obtained by dispersion is 10 mg / mL - 20 mg / mL.

7. A perovskite solar cell, characterized in that, The perovskite solar cell includes the hole transport layer described in claim 1.

8. The perovskite solar cell according to claim 7, wherein, The structure of the perovskite solar cell includes a transparent conductive layer, a hole transport layer, a perovskite absorption layer, an electron transport layer, and an electrode arranged in sequence; Preferably, the thickness of the hole transport layer is 10 nm - 300 nm.

9. The perovskite solar cell according to claim 7 or 8, characterized in that, The material of the transparent conductive layer includes any one or a combination of at least two of FTO, ITO, IZO, IWO, or AZO; Preferably, the material of the perovskite absorption layer includes MA 0.05 Cs 0.05 FA 0.9 Pb(I 0.95 Br 0.05 )3, CH3NH3PbI3, CsPbI3, FAPbI3, or any combination of at least two of CsPbI2Br; Preferably, the material of the electron transport layer includes any one or a combination of at least two of C60, PC 61 BM, PC 71 BM, ICBA, Y6, BCP or tin oxide; Preferably, the electrode includes any one or a combination of at least two of Cu, Au, Ag, or Al.

10. A method for preparing a perovskite solar cell according to any one of claims 7-9, characterized in that, The preparation method includes the following steps: (1) Set the hole transport layer described in claim 1 on the surface of the transparent conductive layer; (2) Set the perovskite absorption layer on the surface of the hole transport layer away from the transparent conductive layer; (3) Set the electron transport layer on the surface of the perovskite absorption layer away from the electron layer; (4) Set the electrode on the surface of the electron transport layer away from the perovskite absorption layer.

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