Perovskite solar cell and preparation method thereof

Abstract

The application provides a perovskite solar cell and a preparation method thereof, and belongs to the technical field of perovskite solar cells. In the direction from the substrate to the electrode layer, the perovskite solar cell comprises a substrate, a first carrier transport layer, a perovskite light-absorbing layer, an interface passivation layer, a second carrier transport layer and an electrode layer which are sequentially arranged; and the material of the interface passivation layer comprises a COFs material. The interface passivation layer is arranged on one side of the perovskite light-absorbing layer in the perovskite solar cell, and the material of the interface passivation layer is designed to comprise a COFs material with a specific structure. The COFs material has a large number of water adsorption sites, exhibits super-high water absorption capacity, and simultaneously realizes accurate regulation of the number of carbonyl groups in the channel and the proportion of hydrophilicity through water adsorption site engineering. The introduction of the COFs material can significantly reduce the erosion of water vapor on the perovskite layer, and improve the electrical performance and stability of the perovskite solar cell.

Description

Technical Field

[0001] This invention belongs to the field of perovskite battery technology, specifically relating to a perovskite solar cell and its preparation method. Background Technology

[0002] With the continuous development of human society, the demand for energy is increasing. Traditional energy sources, such as oil, natural gas, and coal, are non-renewable. Not only are their reserves dwindling, but they also cause significant environmental pollution. Therefore, vigorously developing renewable, green, and clean energy sources is extremely urgent and important. Solar energy is particularly prominent, as it is inexhaustible and does not impact the environment, and its application research has received increasing attention. Developing clean, pollution-free, and abundant solar energy has become a hot topic of research for scientists. Organic-inorganic hybrid perovskite solar cells (PSCs) have significant advantages such as low cost, high conversion efficiency, and suitability for industrial production. Since their introduction in 2009, their photoelectric conversion efficiency has rapidly increased to 26.4%.

[0003] The most challenging issue for perovskite scaffolds (PCSs) is their long-term stability, which must be addressed before they can be applied in practical applications. It is well known that the stability of PCSs in harsh environments (such as heat treatment, lighting, and humidity) appears to be a major bottleneck hindering their commercialization. Among these factors, water undoubtedly has the most severe impact on PCS stability. Water molecules rapidly and readily form hydrogen bonds with non-coordinated I atoms on the perovskite surface, effectively reducing non-radiative recombination. Water vapor then penetrates the perovskite surface and structural boundaries, forming reversible intermediates MAPbI3-H2O and MAPbI3-2H2O hydrates. Through strong hydrogen bonds between water and organic cations, the bonding between organic cations and the inorganic PbI6 scaffold can be weakened; this step is considered a key step in water-induced perovskite degradation. Furthermore, water can also protonate iodides to form volatile halide acids. Additionally, low humidity may be beneficial to the morphology and carrier behavior of perovskites during deposition. However, it has been demonstrated that water severely damages perovskites in high-humidity environments or during long-term use. It is worth noting that CsPbI3, a wide-bandgap perovskite used in tandem solar cells, is highly sensitive to moisture; atmospheric moisture can significantly accelerate the black-to-yellow phase transition. Therefore, to prevent moisture damage to PSCs during long-term use, materials can be used to capture moisture, thereby improving the stability of perovskite solar cells. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a perovskite solar cell and its fabrication method. The present invention involves setting an interface passivation layer on one side of the perovskite light-absorbing layer in the perovskite solar cell. The passivation layer is designed to be made of a COF (covalent organic framework) material with a specific structure. This COF material possesses numerous water adsorption sites, exhibiting extremely high water absorption capacity. Furthermore, the engineering of these water adsorption sites allows for precise control of the number of carbonyl groups and the hydrophilicity ratio within the pores. The introduction of this COF material significantly reduces the erosion of the perovskite layer by water vapor, thereby improving the electrical performance and stability of the perovskite solar cell.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a perovskite solar cell, wherein, from the substrate to the electrode layer, the perovskite solar cell comprises, sequentially disposed, a substrate, a first carrier transport layer, a perovskite light-absorbing layer, an interface passivation layer, a second carrier transport layer, and an electrode layer; the material of the interface passivation layer comprises a COFs material, and the COFs material has a structural unit as shown in Formula I:

[0007] ;

[0008] Among them, Ar1, Ar2, and Ar3 each independently represent the trivalent aryl group of C6-C20. , or Any one of them; the dashed line represents the extension connection point of the I structural unit, and the wavy line represents the connection point of Ar1, Ar2, and Ar3 in the I structural unit.

[0009] This invention involves creating an interface passivation layer on one side of the perovskite light-absorbing layer in a perovskite solar cell. The passivation layer is designed to be made of a COF (covalent organic framework) material with a specific structure. This COF material possesses numerous water adsorption sites, exhibiting extremely high water absorption capacity. Furthermore, the engineering of these water adsorption sites allows for precise control of the number of carbonyl groups and the hydrophilicity ratio within the pores. The introduction of this COF material significantly reduces the erosion of the perovskite layer by water vapor, thereby improving the electrical performance and stability of the perovskite solar cell.

[0010] Furthermore, this COF material contains abundant carbonyl and amino groups, both of which can interact with uncoordinated Pb groups on the perovskite surface. 2+ Coordination bonds are formed, surface defects are passivated, and thus the quality of perovskite films is improved.

[0011] In this invention, C6-C20 can be C6, C7, C8, C10, C12, C13, C15, C18 or C20, etc.

[0012] The COFs material provided by this invention uses the structural unit of Formula I above as the basic repeating unit, extending along the dotted lines. Taking Ar1, Ar2, and Ar3 as the same (denoted as Ar), the extended structure is shown below:

[0013] .

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0015] Preferably, the trivalent aryl group of the C6-C20 group is selected from any one of the following groups: , , , , , , The dashed lines represent the extension connection sites of the trivalent aryl groups of C6-C20 in the structural unit of Formula I, and the wavy lines represent the connection sites of the trivalent aryl groups of C6-C20 in the structural unit of Formula I.

[0016] Preferably, Ar1, Ar2, and Ar3 are each represented independently. , , , Any one of them, the dashed line represents the extension connection point of Ar1, Ar2, and Ar3 in the structural unit of Formula I, and the wavy line represents the connection point of Ar1, Ar2, and Ar3 in the structural unit of Formula I.

[0017] Preferably, Ar1, Ar2, and Ar3 are the same.

[0018] Preferably, the COFs material is selected from at least one of the following: COFs-A, COFs-B, COFs-C, and COFs-D, where dashed lines indicate connection sites:

[0019] , , , .

[0020] Preferably, the COFs material is prepared by the following method, which includes the following steps:

[0021] (1) Add a solution containing trialdehyde phloroglucinol to a solution containing p-phenylenediamine and react to obtain the intermediate;

[0022] ;

[0023] (2) The intermediate and the trialdehyde compound react to obtain the COFs material;

[0024] The trialdehyde compounds include C6-C20 aromatic compounds containing three aldehyde groups.

[0025] Preferably, the concentration of trialdehyde-resorcinol in the solution containing trialdehyde is 8-12 mmol / L, for example, it can be 8 mmol / L, 8.5 mmol / L, 9 mmol / L, 9.5 mmol / L, 10 mmol / L, 10.5 mmol / L, 11 mmol / L, 11.5 mmol / L or 12 mmol / L, etc.

[0026] Preferably, solvent A in the solution containing trialdehyde-resorcinol includes chloroform.

[0027] Preferably, the concentration of p-phenylenediamine in the solution is 60-70 mmol / L, for example, it can be 60 mmol / L, 61 mmol / L, 62 mmol / L, 63 mmol / L, 64 mmol / L, 65 mmol / L, 66 mmol / L, 67 mmol / L, 68 mmol / L, 69 mmol / L or 70 mmol / L, etc.

[0028] Preferably, solvent B in the solution containing p-phenylenediamine includes ethanol.

[0029] Preferably, the molar ratio of the trialdehyde phloroglucinol to p-phenylenediamine is 1:(8-12), for example, it can be 1:8, 1:8.5, 1:9, 1:9.5, 1:10, 1:10.5, 1:11, 1:11.5 or 1:12, etc.

[0030] Preferably, the trialdehyde compound is selected from trimesonol ( ), 2-hydroxy-1,3,5-benzyltrialdehyde ( ), 2,4-dihydroxy-1,3,5-pyromellitic methyl ester ( ) or trialdehyde phloroglucinol ( At least one of the following.

[0031] Preferably, the molar ratio of the intermediate to the trialdehyde compound is 1:(0.8-1.2), for example, it can be 1:0.8, 1:0.9, 1:1, 1:1.1 or 1:1.2, etc.

[0032] Preferably, the method of addition in step (1) includes dropwise addition.

[0033] Preferably, the dropping rate is 180-220 μL / min, for example, it can be 180 μL / min, 185 μL / min, 190 μL / min, 195 μL / min, 200 μL / min, 205 μL / min, 210 μL / min, 215 μL / min or 220 μL / min, etc.

[0034] Preferably, the reaction temperature in step (1) is 60-70℃ (e.g., 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃ or 70℃, etc.), and the time is 1-2 h (e.g., 1 h, 1.5 h or 2 h, etc.).

[0035] Preferably, the reaction in step (1) further includes a post-processing step, wherein the post-processing method includes filtration, washing, and drying.

[0036] The solvents used in the washing process in step (1) include ethanol and chloroform.

[0037] Preferably, the reaction in step (2) is carried out in the presence of solvent C, which includes any one or a combination of at least two of the following: mesitylene, 1,4-dioxane, acetic acid, n-butanol, o-dichlorobenzene, or deionized water.

[0038] In this invention, there are no special restrictions on the amount of solvent C used, and the design can be made according to the actual situation.

[0039] In this invention, step (2) before the reaction also includes a step of mixing the intermediate, the trialdehyde compound and the solvent C. This invention does not have any special restrictions on the mixing method, as long as the three can be mixed evenly.

[0040] Preferably, the reaction temperature in step (2) is 110-130℃ (e.g., it can be 110℃, 112℃, 114℃, 116℃, 118℃, 120℃, 122℃, 124℃, 126℃, 128℃ or 130℃, etc.), and the time is 2-4 days (e.g., it can be 2 days, 2.5 days, 3 days, 3.5 days or 4 days, etc.).

[0041] Preferably, step (2) further includes vacuum treatment before the reaction. The vacuum treatment method includes: freezing the reaction system in a liquid nitrogen bath, and then sealing it under vacuum after three times of degassing using a freeze-evacuate-thaw technique.

[0042] Preferably, step (2) further includes a post-processing step after the reaction, and the post-processing method includes filtration, washing, and drying.

[0043] The washing method in the post-processing step (2) includes: washing with DMF (e.g., washing 8 times, using 5 mL each time, recorded as 8×5 mL), and then extracting with tetrahydrofuran using a Soxhlet extractor for 24 h.

[0044] In this invention, there are no special restrictions on the temperature and time of vacuum drying, as long as the final product can be dried. The vacuum drying temperature is, for example, 120°C, and the vacuum drying time is, for example, 12 h.

[0045] Preferably, the COFs material is prepared by the following method, which specifically includes the following steps:

[0046] (1) A solution containing trialdehyde phloroglucinol with a concentration of 8-12 mmol / L was added dropwise to a solution containing p-phenylenediamine with a concentration of 60-70 mmol / L at a dropping rate of 180-220 μL / min. The mixture was then reacted at 60-70℃ for 1-2 h. The mixture was filtered, washed with ethanol and chloroform, and dried to obtain an intermediate. The molar ratio of trialdehyde phloroglucinol to p-phenylenediamine was 1:(8-12).

[0047] (2) After the intermediate, trialdehyde compound and solvent C are mixed evenly, the reaction system is frozen in a liquid nitrogen bath and the air is vented three times using the freeze-vacuum-thaw technique. The system is then sealed under vacuum and reacted at 110-130℃ for 2-4 days. After filtration, the system is washed with DMF (8×5 mL) and then extracted with tetrahydrofuran using a Soxhlet extractor for 24 h. The system is then vacuum dried at 120℃ for 12 h to obtain the COFs material.

[0048] Preferably, the thickness of the interface passivation layer is 20-100 nm, for example, it can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0049] This invention can further improve the overall performance of perovskite solar cells by controlling the thickness of the interface passivation layer within the range of 20-100 nm.

[0050] Preferably, the thickness of the perovskite light-absorbing layer is 300-700 nm, for example, it can be 300 nm, or 300 nm, 330 nm, 360 nm, 390 nm, 420 nm, 460 nm, 490 nm, 520 nm, 550 nm, 570 nm, 600 nm, 630 nm, 660 nm or 700 nm, etc.

[0051] Preferably, the first carrier transport layer is a hole transport layer and the second carrier transport layer is an electron transport layer; or, the first carrier transport layer is an electron transport layer and the second carrier transport layer is a hole transport layer.

[0052] The perovskite solar cell provided by this invention comprises, from bottom to top, a substrate, a hole transport layer, a perovskite light-absorbing layer, an interface passivation layer, an electron transport layer, and an electrode layer;

[0053] Alternatively, the perovskite solar cell may include, from bottom to top, a substrate, an electron transport layer, a perovskite light-absorbing layer, an interface passivation layer, a hole transport layer, and an electrode layer.

[0054] It should be noted that there are no special restrictions on the specific choice of substrate in this invention. Commonly used substrates in the art are applicable, including but not limited to: conductive glass or power-generating crystalline silicon cells. If the substrate is selected from conductive glass, the perovskite solar cell included in this invention is a single-junction perovskite solar cell; if the substrate is selected from power-generating crystalline silicon cells, the perovskite solar cell included in this invention is a tandem cell, where the perovskite top cell and the bottom cell (substrate, power-generating crystalline silicon cell) are connected in series to generate electricity.

[0055] This invention does not impose any special limitations on the thickness range of the conductive glass. Commonly used thickness ranges in the art are applicable. The thickness of the conductive glass is exemplary but not limited to: 80-150 nm, for example, it can be 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm or 150 nm, etc.

[0056] This invention does not have any special design for the structure of the power-generating crystalline silicon cell; it is applicable to all commonly used power-generating crystalline silicon cells in the field.

[0057] In this invention, the material of the hole transport layer can be a p-type semiconductor material, including any one of polymers, organic compounds, or inorganic compounds; the polymer includes at least one of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), poly(3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS), 4-butyl-N,N-diphenylaniline homopolymer (Ploy-TPD), and polyvinylcarbazole (PVK); the inorganic compound includes at least one of NiOx, CuI, and CuSCN; the organic compound includes at least one of 2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz) and its derivatives.

[0058] In this invention, if the hole transport layer is made of an organic compound, its thickness can be 1-3 nm, for example, 1 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2 nm, 2.2 nm, 2.4 nm, 2.6 nm, 2.8 nm, or 3 nm. If the hole transport layer is made of a polymer, its thickness can be 20-100 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm. If the hole transport layer is made of an inorganic compound, its thickness can be 10-30 nm, for example, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, or 30 nm.

[0059] In this invention, the perovskite light-absorbing layer is prepared from a perovskite precursor solution, wherein the perovskite precursor contains ABX3 perovskite material, where A is CH3NH3. + CH(NH2)2 + Cs + or Rb + B is any combination of one or at least two of the following, where B is Pb. 2+ Sn 2+ Or Ge 2+ Any combination of one or at least two of them, X is Cl ¯ ,Br ¯ or I ¯ The solvent of the perovskite precursor solution includes any one or a combination of at least two of the following: N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL), 1,3-dimethyl-2-imidazolinone (DMI), dimethylacetamide (DMAC), N,N-dimethylpropenylurea (DMPU), acetonitrile (ACN), or 2-mercaptoethanol (2-ME).

[0060] It should be noted that the present invention does not impose any special restrictions on the mass concentration of perovskite material in the perovskite precursor solution, and the mass concentration range commonly used in the art is applicable.

[0061] In this invention, the material of the electron transport layer can be an n-type semiconductor material, including C 60 Any one of PCBM, BCP, TiO2, SnO2, ZnO, or ZnO-ZnS.

[0062] In this invention, the thickness of the electron transport layer can be 10-40 nm, for example, it can be 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm or 40 nm, etc.

[0063] In this invention, the electrode layer material can be any one of Al, Au, Ag, Cu or carbon electrodes.

[0064] In this scheme, the thickness of the electrode layer can be 80-120 nm, for example, it can be 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm or 120 nm, etc.

[0065] In a second aspect, the present invention provides a method for fabricating a perovskite solar cell as described in the first aspect, the method comprising the following steps: sequentially depositing a first carrier transport layer, a perovskite light-absorbing layer, an interface passivation layer, a second carrier transport layer, and an electrode layer on one side of a substrate to obtain the perovskite solar cell.

[0066] Preferably, the method for setting the interface passivation layer includes the following steps: coating an interface passivation material precursor solution onto the side of the perovskite light-absorbing layer away from the first carrier transport layer, annealing, and obtaining the interface passivation layer; the interface passivation material precursor solution includes the COFs material as described in the first aspect.

[0067] Preferably, the interface passivation material precursor solution is prepared by the following method, which includes the following steps: mixing COFs material and solvent D to obtain the interface passivation material precursor solution.

[0068] Preferably, the solvent D includes any one or a combination of at least two of isopropanol, ethanol, butanol, methanol, or acetone.

[0069] In this invention, there are no special restrictions on the mixing method of COFs material and solvent D, as long as it can be mixed uniformly, and commonly used mixing methods in the art are applicable.

[0070] Preferably, the concentration of COFs material in the interface passivation material precursor solution is 1-5 mg / mL, for example, it can be 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL or 5 mg / mL, etc.

[0071] Preferably, the coating method includes spin coating.

[0072] Preferably, the spin coating speed is 3000-5000 rpm, for example, it can be 3000 rpm, 3200 rpm, 3400 rpm, 3600 rpm, 3800 rpm, 4000 rpm, 4200 rpm, 4400 rpm, 4600 rpm, 4800 rpm or 5000 rpm, etc.

[0073] Preferably, the spin coating time is 25-35 s, for example, it can be 25 s, 26 s, 27 s, 28 s, 29 s, 30 s, 31 s, 32 s, 33 s, 34 s or 35 s, etc.

[0074] Preferably, the annealing temperature is 70-90℃ (e.g., 70℃, 72℃, 74℃, 76℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃, or 90℃, etc.), and the time is 4-8 min (e.g., 4 min, 4.5 min, 5 min, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, or 8 min, etc.).

[0075] It should be noted that the present invention does not impose any special limitations on the method of forming a first carrier transport layer, a perovskite light-absorbing layer, a second carrier transport layer, and an electrode layer on one side of the conductive substrate in a perovskite solar cell. Taking a conductive glass substrate, a hole transport layer as the first carrier transport layer, and an electron transport layer as the second carrier transport layer as an example, the fabrication method of the perovskite solar cell exemplarily includes the following steps:

[0076] (1) Pretreatment of the substrate;

[0077] (2) Spin-coating a hole transport material precursor solution onto one side of the substrate and annealing to obtain a hole transport layer;

[0078] (3) Coat the hole transport layer with a perovskite precursor solution on the side away from the substrate, anneal it, and form a perovskite light-absorbing layer (thin film light-absorbing layer).

[0079] (4) Spin-coating an interface passivation material precursor solution onto the side of the perovskite layer away from the substrate, and annealing to obtain the interface passivation layer;

[0080] (5) An electron transport layer is provided on the side of the interface passivation layer away from the substrate;

[0081] (6) An electrode layer is disposed on the side of the electron transport layer away from the substrate to obtain the perovskite solar cell.

[0082] Preferably, the pretreatment method in step (1) includes washing (including ultrasonic cleaning with detergent, deionized water, acetone and anhydrous ethanol respectively) and drying (including drying with a nitrogen gun).

[0083] Preferably, the coating method in step (2) includes spin coating, wherein the spin coating speed is 2500-3500 rpm (e.g., 2500 rpm, 2600 rpm, 2700 rpm, 2800 rpm, 2900 rpm, 3000 rpm, 3100 rpm, 3200 rpm, 3300 rpm, 3400 rpm or 3500 rpm, etc.), and the time is 25-35 s (e.g., 25 s, 26 s, 27 s, 28 s, 29 s, 30 s, 31 s, 32 s, 33 s, 34 s or 35 s, etc.).

[0084] Preferably, the annealing temperature in step (2) is 90-110℃ (e.g., 90℃, 92℃, 94℃, 96℃, 98℃, 100℃, 102℃, 104℃, 106℃, 108℃ or 110℃, etc.), and the time is 8-12 min (e.g., 8 min, 9 min, 10 min, 11 min or 12 min, etc.).

[0085] Preferably, the coating method in step (3) includes spin coating, wherein the spin coating speed is 4500-5500 rpm (e.g., 4500 rpm, 4600 rpm, 4700 rpm, 4800 rpm, 4900 rpm, 5000 rpm, 5100 rpm, 5200 rpm, 5300 rpm, 5400 rpm or 5500 rpm, etc.), and the time is 45-55 s (e.g., 45 s, 46 s, 47 s, 48 ​​s, 49 s, 50 s, 51 s, 52 s, 53 s, 54 s or 55 s, etc.).

[0086] Preferably, the annealing temperature in step (3) is 110-130℃ (e.g., 110℃, 112℃, 114℃, 116℃, 118℃, 120℃, 122℃, 124℃, 126℃, 128℃ or 130℃, etc.), and the time is 12-18 min (e.g., 12 min, 13 min, 14 min, 15 min, 16 min, 17 min or 18 min, etc.).

[0087] Preferably, the method for setting the electron transport layer in step (5) includes vacuum evaporation.

[0088] Preferably, the method for setting the electrode layer in step (6) includes vacuum evaporation.

[0089] It should be noted that the present invention does not impose any special restrictions on the process conditions of vacuum evaporation when setting electron transport layers and electrode layers by vacuum evaporation, and the process conditions commonly used in the art are applicable.

[0090] Compared with the prior art, the present invention has the following beneficial effects:

[0091] (1) This invention designs the structure of a perovskite solar cell, and further sets an interface passivation layer between the perovskite light-absorbing layer and the second carrier transport layer. The material of the interface passivation layer is designed. By using COFs materials with specific structures, the erosion of the perovskite layer by water vapor can be significantly reduced. At the same time, the COFs materials contain abundant carbonyl and amino groups, which can interact with the uncoordinated Pb on the perovskite surface. 2+ By forming coordination bonds and passivating surface defects, the quality of the perovskite thin film is improved, thereby enhancing the electrical performance and stability of the perovskite solar cell. The resulting perovskite solar cell exhibits an open-circuit voltage (Voc) of 1.17–1.21 V and a short-circuit current density (Jsc) of 24.6–25.5 mA / cm². 2 The fill factor (FF) is 76.4-78.3%, and the photoelectric conversion efficiency (PCE) is 22.2-23.7%.

[0092] (2) By further controlling the thickness of the interface passivation layer within a specific range, the present invention further improves the overall performance of perovskite solar cells. Attached Figure Description

[0093] Figure 1 This is the infrared spectrum of the intermediate provided in Preparation Example 1 of this invention;

[0094] Figure 2 This is the infrared spectrum of the COFs-A material provided in Preparation Example 1 of this invention;

[0095] Figure 3 This is the infrared spectrum of the COFs-B material provided in Preparation Example 2 of this invention;

[0096] Figure 4 This is the infrared spectrum of the COFs-C material provided in Preparation Example 3 of this invention;

[0097] Figure 5 This is the infrared spectrum of the COFs-D material provided in Preparation Example 4 of this invention;

[0098] Figure 6 This is a comparison chart of the JV curves of the perovskite solar cells provided in Embodiment 1 and Comparative Example 1 of the present invention;

[0099] Figure 7 This is a comparison chart of the photoelectric conversion efficiency (PCE)-time curves of the perovskite solar cells provided in Embodiments 1, 7, 8 and Comparative Example 1 of the present invention. Detailed Implementation

[0100] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be considered as specific limitations thereof.

[0101] The sources of some components in the following examples and comparative examples are as follows:

[0102] Transparent conductive substrate: purchased from Liaoning Youxuan, item number: YXKJPI-0002;

[0103] MeO-2PACz and CsI were purchased from TCI;

[0104] FAI, MAI, MACl, and BCP were purchased from Xi'an Yulu Solar Energy.

[0105] PbI2, DMSO, and DMF were purchased from Sigma.

[0106] C 60 Purchased from Nano-C.

[0107] Preparation Example 1

[0108] This preparation example provides COFs-A material and its preparation method. The synthesis method of COFs-A material is as follows:

[0109] (1) Synthesis of intermediates

[0110]

[0111] Trialdehyde phloroglucinol (210 mg, 1.0 mmol) and CHCl3 (100 mL) were added to a 200 mL beaker and sonicated at room temperature for 30 min (ultrasonic power 25 W) to form a pale yellow transparent solution. In a 250 mL two-necked flask, p-phenylenediamine (1081 mg, 10.0 mmol) and ethanol (150 mL) were added. The straight neck was connected to a condenser tube, and the oblique neck was sealed with a rubber stopper connected to a rubber tubing. The two-necked flask was maintained at 65°C. The other end of the rubber tubing was immersed in the beaker using a peristaltic pump. Using the peristaltic pump, the CHCl3 solution containing trialdehyde phloroglucinol was added dropwise to the ethanol solution containing p-phenylenediamine at a rate of 200 μL / min at room temperature (25°C). The reaction was carried out at 65°C for 1 minute. h, the intermediate slowly appeared as an orange precipitate. After the reaction was completed, the mixture was filtered, washed with a mixture of ethanol and CHCl3 (volume ratio of ethanol to CHCl3 was 1:1), and dried under vacuum to obtain the intermediate (231 mg, yield 50%).

[0112] The intermediate was characterized using a Fourier transform infrared spectrometer (Thermo Fisher Nicolet 6700). The characterization results are as follows: Figure 1 As shown. By Figure 1 It can be seen that in the range of 3200-3600 cm -1 The broad absorption peaks indicate that the molecule contains a large number of amino groups, consistent with the substitution structure of triphenylamine; the peaks at 1600-1700 cm⁻¹... -1 The extremely strong deep valley at 1500 cm⁻¹ proves the existence of a conjugated system of a triketone carbonyl group and an imine C=N group (the core characteristic peak of the intermediate provided in this preparation example); -1 The nearby multiple splitting peaks indicate polycyclic benzene ring skeletal vibrations, proving the presence of multiple para-aminobenzene rings; in the 1000-1350 cm⁻¹ range... -1 The presence of CN stretching vibration peaks indicates the existence of CN bonds in the aromatic amine structure, matching the numerous aromatic amine structures within the molecule; and also... Figure 1 It can be seen that there are no extraneous alkyl, hydroxyl, carboxyl or other impurity peaks. All infrared absorption peaks can be completely explained by the functional groups of the target intermediate structure. The spectrum is in high agreement with the molecular structure, indicating that the intermediate was successfully prepared.

[0113] (2) Synthesis of COFs-A materials

[0114]

[0115] Synthesized by solvothermal condensation reaction: In a Pyrex tube, the intermediate (14.43 mg, 0.03 mmol) and trimesin (4.86 mg, 0.03 mmol) were dissolved in a mixed solvent containing 1.8 mL n-butanol, 0.2 mL o-dichlorobenzene, and 0.2 mL acetic acid (6 M concentration, deionized water). The mixture was sonicated at 25 W for 10 min to obtain a uniform dispersion. The Pyrex tube was rapidly frozen in a liquid nitrogen bath and degassed three times using a freeze-evacuation-thaw technique. After being sealed under vacuum, the tube was placed in an oven and reacted at 120 °C for 3 days. The precipitate was collected by filtration, washed with DMF (8 × 5 mL), extracted with tetrahydrofuran using a Soxhlet extractor for 24 h, and finally dried under vacuum at 120 °C for 12 h to obtain orange crystalline powder COFs-A material (3.78 mg, yield 71%).

[0116] The COFs-A material was characterized using a Fourier transform infrared spectrometer (Thermo Fisher Nicolet 6700). The characterization results are as follows: Figure 2 As shown. By Figure 2 It can be known that 3200-3600 cm -1 The broad absorption band at 3030 cm⁻¹ is due to intramolecular hydrogen bonding and represents the NH stretching vibration peak of aromatic secondary amines. -1 Represents aromatic rings (sp) 2 Hybridized CH stretching vibration peaks, and no 2800 / 2900 cm⁻¹ peaks. -1 The presence of saturated alkyl CH peaks confirms that the skeleton contains only aromatic unsaturated structures; 1600-1700 cm⁻¹ -1 The strongest absorption peak represents the coupling of the C=O stretching vibration of conjugated cyclohexanetrione and the C=N stretching vibration of the imine formed by condensation. This characteristic peak simultaneously contains signals from the conjugated carbonyl group and a large number of imine bonds, which is the core evidence for amino-aldehyde condensation and the formation of the cyclic skeleton of COFs; 1480-1600 cm⁻¹ -1 Represents the stretching vibration of the C=C skeleton of para-substituted benzene rings, secondary amines ( The in-plane bending vibration peaks (where the dashed lines represent the linkage sites of secondary amine groups) and the multiple splitting peaks demonstrate the large number of para-benzene ring units in the molecule; 1200-1350 cm⁻¹ -1 The peak represents the stretching vibration of the aromatic CN single bond, corresponding to the Ar-NH-C= bridging structure (Ar represents the aromatic ring, i.e., the benzene ring in the COFs-A material, the same below); 800-850 cm⁻¹ -1 The out-of-plane bending vibration peak representing the para-disubstituted benzene CH further confirms the complete preservation of the 4-aminophenyl structural unit, indicating the successful preparation of the COFs-A material.

[0117] Preparation Example 2

[0118] This preparation example provides COFs-B material and its preparation method. The synthesis method of COFs-B material is as follows:

[0119] (1) Synthesis of intermediates

[0120] The intermediate was synthesized according to the synthesis method of the intermediate provided in Preparation Example 1;

[0121] (2) Synthesis of COFs-B materials

[0122]

[0123] Following the synthesis method of COFs-A material provided in Preparation Example 1, COFs-B material was synthesized, with the only difference from Preparation Example 1 being: replacing pyromellitic aldehyde (4.86 mg, 0.03 mmol) with 2-hydroxy-1,3,5-phenyltricarboxaldehyde (5.34 mg, 0.03 mmol), and replacing 0.2 mL of acetic acid solution (concentration 6 M, solvent deionized water) with 0.2 mL of acetic acid solution (concentration 3 M, solvent deionized water). All other conditions were the same, and black crystalline powder COFs-B material (3.95 mg, yield 68%) was obtained.

[0124] The COFs-B material was characterized using a Fourier transform infrared spectrometer (Thermo Fisher Nicolet 6700). The characterization results are as follows: Figure 3 As shown. By Figure 3 It can be known that 3200-3600 cm -1 The broad absorption band at 3030 cm⁻¹ represents the NH stretching vibration of an aromatic secondary amine; -1 Represents aromatic rings (sp) 2 Hybridized CH stretching vibration peaks, and no 2800 / 2900 cm⁻¹ peaks. -1 The presence of saturated alkyl CH peaks confirms that the skeleton contains only aromatic unsaturated structures; 1600-1700 cm⁻¹ -1 The strongest absorption represents the coupling of the stretching vibrations of the imine formed by the stretching and condensation of the conjugated six-membered ring C=O, and is also core characteristic evidence of the successful construction of the cyclic skeleton of COFs through the condensation of amino and aldehyde groups; 1480-1600 cm⁻¹ -1 The peaks represent the C=C skeletal stretching vibration of the para-substituted benzene ring and the in-plane bending vibration of the secondary amine; the multiple splitting peaks indicate a large number of para-benzene ring units in the molecule; 1200-1350 cm⁻¹ -1 Represents the stretching vibration peak of the aromatic CN single bond, corresponding to the Ar-NH-C= bridging structure in the framework; 800-850 cm⁻¹ -1The out-of-plane bending vibration peak representing the para-disubstituted benzene CH further confirms the complete preservation of the 4-aminophenyl structural unit, indicating the successful preparation of the COFs-B material.

[0125] Preparation Example 3

[0126] This preparation example provides COFs-C materials and their preparation methods. The synthesis method of COFs-C materials is as follows:

[0127] (1) Synthesis of intermediates

[0128] The intermediate was synthesized according to the synthesis method of the intermediate provided in Preparation Example 1;

[0129] (2) Synthesis of COFs-C materials

[0130]

[0131] Following the synthesis method of COFs-A material provided in Preparation Example 1, COFs-C material was synthesized, with the only difference being that: pyromellitic tricarboxaldehyde (4.86 mg, 0.03 mmol) was replaced with 2,4-dihydroxy-1,3,5-pyromellitic tricarboxaldehyde (5.82 mg, 0.03 mmol), and 0.2 mL of acetic acid solution (6 M concentration, deionized water solvent) was replaced with 0.2 mL of acetic acid solution (3 M concentration, deionized water solvent). All other conditions were the same, and black crystalline powder COFs-C material (3.90 mg, yield 62%) was obtained.

[0132] The COFs-C material was characterized using a Fourier transform infrared spectrometer (Thermo Fisher Nicolet 6700). The characterization results are as follows: Figure 4 As shown. By Figure 4 It can be known that 3200-3600 cm -1 The broad absorption band at 3030 cm⁻¹ represents the NH stretching vibration of an aromatic secondary amine; -1 Represents aromatic rings (sp) 2 Hybridized CH stretching vibration peaks, and no 2800 / 2900 cm⁻¹ peaks. -1 The presence of saturated alkyl CH peaks confirms that the skeleton contains only aromatic unsaturated structures; 1600-1700 cm⁻¹ -1 The strongest absorption represents the coupling of the stretching vibrations of the imine formed by the stretching and condensation of the conjugated six-membered ring C=O, and is also core characteristic evidence of the successful construction of the cyclic skeleton of COFs through the condensation of amino and aldehyde groups; 1480-1600 cm⁻¹ -1 The peaks represent the C=C skeletal stretching vibration of the para-substituted benzene ring and the in-plane bending vibration of the secondary amine; the multiple splitting peaks indicate a large number of para-benzene ring units in the molecule; 1200-1350 cm⁻¹ -1Represents the stretching vibration peak of the aromatic CN single bond, corresponding to the Ar-NH-C= bridging structure in the framework; 800-850 cm⁻¹ -1 The out-of-plane bending vibration peak representing the para-disubstituted benzene CH further confirms the complete preservation of the 4-aminophenyl structural unit, indicating the successful preparation of the COFs-C material.

[0133] Preparation Example 4

[0134] This preparation example provides COFs-D materials and their preparation methods. The synthesis method of COFs-D materials is as follows:

[0135] (1) Synthesis of intermediates

[0136] The intermediate was synthesized according to the synthesis method of the intermediate provided in Preparation Example 1;

[0137] (2) Synthesis of COFs-D materials

[0138]

[0139] Following the synthesis method of COFs-A material provided in Preparation Example 1, COFs-D material was synthesized, with the only difference from Preparation Example 1 being: pyromellitic aldehyde (4.86 mg, 0.03 mmol) was replaced with trialdehyde phloroglucinol (6.30 mg, 0.03 mmol), and all other conditions were the same. Additionally, 0.2 mL of acetic acid solution (6 M concentration, deionized water solvent) was replaced with 0.2 mL of acetic acid solution (3 M concentration, deionized water solvent) to obtain red crystalline powder COFs-D material (4.94 mg, yield 73%).

[0140] The COFs-D materials were characterized using a Fourier transform infrared spectrometer (Thermo Fisher Nicolet 6700). The characterization results are as follows: Figure 5 As shown. By Figure 5 It can be known that 3200-3600 cm -1 The broad absorption band at 3030 cm⁻¹ represents the NH stretching vibration of an aromatic secondary amine; -1 Represents aromatic rings (sp) 2 Hybridized CH stretching vibration peaks, and no 2800 / 2900 cm⁻¹ peaks. -1 The presence of saturated alkyl CH peaks confirms that the skeleton contains only aromatic unsaturated structures; 1600-1700 cm⁻¹ -1 The strongest absorption represents the coupling of the stretching vibrations of the imine formed by the stretching and condensation of the conjugated six-membered ring C=O, and is also core characteristic evidence of the successful construction of the cyclic skeleton of COFs through the condensation of amino and aldehyde groups; 1480-1600 cm⁻¹ -1The peaks represent the C=C skeletal stretching vibration of the para-substituted benzene ring and the in-plane bending vibration of the secondary amine; the multiple splitting peaks indicate a large number of para-benzene ring units in the molecule; 1200-1350 cm⁻¹ -1 Represents the stretching vibration peak of the aromatic CN single bond, corresponding to the Ar-NH-C= bridging structure in the framework; 800-850 cm⁻¹ -1 The out-of-plane bending vibration peak representing the para-disubstituted benzene CH further confirms the complete preservation of the 4-aminophenyl structural unit, indicating the successful preparation of the COFs-D material.

[0141] The four COFs materials exhibit consistent overall infrared peak positions, stemming from the presence of similar functional groups such as conjugated ketone carbonyl groups, imine bonds, aromatic secondary amines, and para-benzene rings in their molecules. However, they also exhibit subtle, distinguishable spectral differences arising from variations in topological ring size, carbonyl substitution sites, conjugated chain length, and intramolecular hydrogen bond strength, manifested in three observable features:

[0142] ① 3200-3600 cm -1 The depth and broadening degree of the NH broad absorption valley;

[0143] ② 1600-1700 cm -1 The number of sub-peaks splitting and relative absorption intensity within the main absorption band;

[0144] ③ 1000-1400 cm -1 The transmittance ratio of CN and the secondary peak of the aromatic ring bending in the fingerprint region;

[0145] The subtle differences in infrared fingerprints mentioned above can be used to distinguish the four different ring-shaped topological structures of COFs materials, proving that there are structural differences in their molecular skeletons.

[0146] Example 1

[0147] This embodiment provides a perovskite solar cell and its fabrication method. From the conductive substrate to the electrode layer, the perovskite solar cell includes a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an interface passivation layer, an electron transport layer, and an electrode layer stacked sequentially.

[0148] The perovskite solar cell is prepared as follows:

[0149] (1) Cleaning the transparent conductive glass includes ultrasonic cleaning with detergent, deionized water, acetone and anhydrous ethanol respectively, and then drying it with a nitrogen gun; wherein the ultrasonic cleaning power is 100 Hz and the ultrasonic cleaning time is 15 min.

[0150] (2) A hole transport layer was deposited on the surface of a transparent conductive glass by spin coating. Specifically, a hole transport layer solution with a concentration of 0.5 mg / mL (ethanol) prepared by [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz) was dropped onto the transparent conductive glass and spin-coated at a speed of 3000 rpm for 30 s. Then, it was annealed at 100℃ for 10 min to obtain a hole transport layer with a thickness of 2 nm.

[0151] (3) A perovskite light-absorbing layer is prepared on the upper surface of the hole transport layer, specifically including:

[0152] CsI ​​(108.33 mg), FAI (1218.34 mg), MAI (132.50 mg), PbI2 (4033.76 mg), and MACl (83.27 mg) were added to a bottle containing a mixed solution of DMF (4200 μL) and DMSO (840 μL), and stirred thoroughly for at least 12 h to form a CsI solution with a final concentration of 1.67 mol / L. 0.05 MA 0.1 FA 0.85 PbI3 perovskite precursor solution;

[0153] The perovskite precursor solution was spin-coated onto the hole transport layer at 5000 rpm for 50 s with an acceleration of 1000 rpm. At 35 s, 200 μL of chlorobenzene was added dropwise. Finally, the mixture was annealed at 120°C for 15 min to crystallize and form Cs. 0.05 MA 0.1 FA 0.85 The PbI3 perovskite light-absorbing layer has a thickness of 450 nm.

[0154] (4) Dissolve the COFs-D material provided in Preparation Example 4 in isopropanol to obtain an interface passivation material precursor solution with a concentration of 3 mg / mL;

[0155] The above-mentioned interface passivation material precursor solution was spin-coated onto the perovskite light-absorbing layer at a spin speed of 4000 rpm for 30 s. Then, it was annealed at 80°C for 6 min to obtain an interface passivation layer with a thickness of 60 nm.

[0156] (5) A C layer is deposited on the surface of the interface passivation layer by vacuum evaporation. 60 The evaporation is carried out under a vacuum of 5×10⁻⁶. -4 The evaporation was carried out under Pa conditions at a rate of 0.15 Å / s, yielding C. 60 The layer is 20 nm thick;

[0157] In C60 A second BCP layer is deposited on the surface of the first layer by vacuum evaporation, wherein the evaporation is performed at a vacuum degree of 5 × 10⁻⁶. -4 The process was carried out under Pa conditions at an evaporation rate of 0.2 Å / s to obtain a BCP layer with a thickness of 8 nm, thus completing the preparation of the electron transport layer;

[0158] (6) A metal electrode is prepared on the surface of the electron transport layer. Specifically, a silver electrode is formed on the surface of the electron transport layer by thermal evaporation in a metal evaporation chamber to obtain an electrode layer with a thickness of 100 nm, thus completing the preparation of the perovskite solar cell. The vacuum degree of the evaporation chamber is 5 × 10⁻⁶. -4 Pa, evaporation rate is 2 Å / s.

[0159] Example 2

[0160] This embodiment provides a perovskite solar cell and its preparation method. The only difference from Example 1 is that the COFs-D material provided in Preparation Example 4 in step (4) is replaced with the COFs-C material provided in Preparation Example 3; other conditions are the same as in Example 1.

[0161] Example 3

[0162] This embodiment provides a perovskite solar cell and its preparation method. The only difference from Example 1 is that the COFs-D material provided in Preparation Example 4 in step (4) is replaced with the COFs-B material provided in Preparation Example 2; other conditions are the same as in Example 1.

[0163] Example 4

[0164] This embodiment provides a perovskite solar cell and its preparation method. The only difference from Example 1 is that the COFs-D material provided in Preparation Example 4 in step (4) is replaced with the COFs-A material provided in Preparation Example 1; other conditions are the same as in Example 1.

[0165] Example 5

[0166] This embodiment provides a perovskite solar cell and its preparation method. The only difference from Example 1 is that the concentration of the interface passivation precursor solution in step (4) is 1 mg / mL, the spin-coating speed of the interface passivation precursor solution is 4500 rpm, the spin-coating time is 30 s, and the thickness of the obtained interface passivation layer is about 20 nm. Other conditions are the same as in Example 1.

[0167] Example 6

[0168] This embodiment provides a perovskite solar cell and its preparation method. The only difference from Example 1 is that the concentration of the interface passivation precursor solution in step (4) is 5 mg / mL, the spin-coating speed of the interface passivation precursor solution is 3500 rpm, the spin-coating time is 30 s, and the thickness of the obtained interface passivation layer is 100 nm. Other conditions are the same as in Example 1.

[0169] Example 7

[0170] This embodiment provides a perovskite solar cell and its preparation method. The only difference from Example 1 is that the concentration of the interface passivation precursor solution in step (4) is 0.5 mg / mL, the spin-coating speed of the interface passivation precursor solution is 5000 rpm, the spin-coating time is 30 s, and the thickness of the obtained interface passivation layer is 10 nm. Other conditions are the same as in Example 1.

[0171] Example 8

[0172] This embodiment provides a perovskite solar cell and its preparation method. The only difference from Example 1 is that the concentration of the interface passivation precursor solution in step (4) is 7 mg / mL, the spin-coating speed of the interface passivation precursor solution is 3000 rpm, the spin-coating time is 30 s, and the thickness of the obtained interface passivation layer is 120 nm. Other conditions are the same as in Example 1.

[0173] Comparative Example 1

[0174] This comparative example provides a perovskite solar cell and its fabrication method. From the conductive substrate to the electrode layer, the perovskite solar cell includes a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and an electrode layer stacked sequentially.

[0175] The above-mentioned perovskite solar cell preparation method refers to the perovskite solar cell preparation method provided in Example 1, the only difference being that step (4) is not performed; other conditions are the same as in Example 1.

[0176] The JV curves of the perovskite light-absorbing layer in the perovskite solar cells provided in Example 1 and Comparative Example 1 were characterized using a solar energy simulation testing system from Taiwan Guangyan Technology Co., Ltd. The comparison of their JV curves is shown in the figure below. Figure 6 As shown. By Figure 6 It can be seen that the open-circuit voltage, short-circuit current density and fill factor of the perovskite solar cell after passivation with the COFs material provided by the present invention are significantly improved. This indicates that the use of COFs material in the present invention can significantly reduce the erosion of the perovskite layer by water vapor, effectively passivate the interface of the perovskite surface, and improve the overall performance of the perovskite solar cell.

[0177] The photoelectric conversion efficiency (PCE)-time curves of the perovskite light-absorbing layer in the perovskite solar cells provided in Examples 1, 7, 8, and Comparative Example 1 were characterized using a solar energy simulation testing system from Taiwan Guangyan Technology Co., Ltd. The PCE-time comparison graphs are shown below. Figure 7 As shown. By Figure 7 It can be seen that the perovskite solar cells treated with COFs materials (provided by Examples 1, 7, and 8) can still maintain more than 80% of their initial photoelectric conversion efficiency after 1000 h, indicating that the perovskite solar cells have good stability. Furthermore, by designing the thickness of the interface passivation layer obtained from COFs materials to be ≥20 nm, the photoelectric conversion efficiency of the perovskite solar cells (provided by Example 1) can still maintain more than 90% of its initial value after 1000 h; while the perovskite solar cells without COFs material treatment (provided by Comparative Example 1) have a faster rate of photoelectric conversion efficiency decay. This is mainly because the COFs materials provided by this invention have a large number of water adsorption sites, which can significantly reduce the erosion of the perovskite layer by water vapor and greatly improve the stability of the perovskite solar cells.

[0178] The performance of the perovskite solar cells provided in the above embodiments and comparative examples was tested and characterized. The specific test methods are as follows:

[0179] Measurements were conducted using a solar energy simulation testing system from Taiwan's Guangyan Technology Co., Ltd. The light source was a 500W xenon lamp solar spectrum simulator, calibrated with a standard KG-5 silicon cell at a solar intensity of 100 mW / cm². 2 Measurements are performed under the following conditions: A continuously varying voltage (-0.5 V - 1.3 V) is applied across the battery terminals, and the battery's output current is measured (using a Keithley 2400 power supply). The product of these two measurements yields the JV test curve, which displays the photoelectric conversion efficiency of the device under different conditions.

[0180] The test data above are shown in Table 1 below:

[0181] Table 1

[0182]

[0183] As described above, this invention designs the structure of a perovskite solar cell, further sets an interface passivation layer between the perovskite light-absorbing layer and the second carrier transport layer, and designs the material of the interface passivation layer. Through the use of COFs materials with a specific structure, the erosion of the perovskite layer by moisture can be significantly reduced. Simultaneously, the COFs materials contain abundant carbonyl and amino groups, both of which can interact with uncoordinated Pb groups on the perovskite surface. 2+Forming coordination bonds and passivating surface defects improves the quality of the perovskite thin film, thereby enhancing the electrical performance of the perovskite solar cell. This results in an open-circuit voltage (Voc) of 1.17-1.21 V and a short-circuit current density (Jsc) of 24.6-25.5 mA / cm². 2 The fill factor (FF) is 76.4-78.3%, and the photoelectric conversion efficiency (PCE) is 22.2-23.7%.

[0184] As can be seen from Examples 1 and 5-8, the present invention further improves the electrical performance of perovskite solar cells by controlling the thickness of the interface passivation layer within a specific range. The open-circuit voltage Voc is 1.20-1.21 V, and the short-circuit current density Jsc is 24.9-25.5 mA / cm². 2 The fill factor (FF) is 77.7-78.3%, and the photoelectric conversion efficiency (PCE) is 23.4-23.7%. When the thickness of the interface passivation layer prepared from the COFs material provided by this invention is too thin (Example 7), the reduction of passivation groups in the COFs has an impact on Pb. 2+ The passivation effect of defects is weakened, resulting in poor film quality and reduced battery efficiency. When the thickness of the interface passivation layer prepared by the COFs material provided by the present invention is too thick (Example 8), it will hinder carrier transport and thus affect battery efficiency.

[0185] As can be seen from Examples 1-8 and Comparative Example 1, the present invention has prepared a perovskite solar cell with excellent performance by setting an interface passivation layer between the perovskite light-absorbing layer and the second carrier transport layer, and designing the structure of the material (COFs material) of the interface passivation layer.

[0186] In summary, this invention, through the design of the perovskite solar cell structure, and further by setting an interface passivation layer between the perovskite light-absorbing layer and the second carrier transport layer, and by designing the material of the interface passivation layer, utilizes COFs materials with a specific structure to significantly reduce the erosion of the perovskite layer by moisture. Simultaneously, the COFs materials contain abundant carbonyl and amino groups, both of which can interact with uncoordinated Pb groups on the perovskite surface. 2+ Forming coordination bonds and passivating surface defects improves the quality of perovskite thin films, thereby enhancing the stability of perovskite solar cells.

[0187] The applicant declares that the detailed process flow of this invention is illustrated by the above embodiments, but this invention is not limited to the above detailed process flow, that is, it does not mean that this invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A perovskite solar cell, characterized in that, From the substrate to the electrode layer, the perovskite solar cell includes a substrate, a first carrier transport layer, a perovskite light-absorbing layer, an interface passivation layer, a second carrier transport layer, and an electrode layer arranged sequentially. The material of the interface passivation layer includes COFs material, which has the structural unit shown in Formula I: ； Among them, Ar1, Ar2, and Ar3 each independently represent the trivalent aryl group of C6-C20. , or Any one of them; The dashed lines represent the extension connection points of the Equation I structural unit, and the wavy lines represent the connection points of Ar1, Ar2, and Ar3 in the Equation I structural unit.

2. The perovskite solar cell according to claim 1, characterized in that, The C6-C20 trivalent aryl group is selected from any one of the following groups: , , , , , , The dashed lines represent the extension connection sites of the trivalent aryl groups of C6-C20 in the structural unit of Formula I, and the wavy lines represent the connection sites of the trivalent aryl groups of C6-C20 in the structural unit of Formula I.

3. The perovskite solar cell according to claim 1, characterized in that, Ar1, Ar2, and Ar3 are each represented independently. , , , Any one of them, the dashed line represents the extension connection point of Ar1, Ar2, and Ar3 in the structural unit of Formula I, and the wavy line represents the connection point of Ar1, Ar2, and Ar3 in the structural unit of Formula I.

4. The perovskite solar cell according to claim 1, characterized in that, The COFs material is selected from at least one of the following: COFs-A, COFs-B, COFs-C, and COFs-D, where dashed lines indicate connection sites: 、 、 、 。 5. The perovskite solar cell according to claim 1, characterized in that, The COFs material was prepared by the following method, which includes the following steps: (1) Add a solution containing trialdehyde phloroglucinol to a solution containing p-phenylenediamine and react to obtain an intermediate; ； (2) The intermediate and the trialdehyde compound react to obtain the COFs material; The trialdehyde compounds include C6-C20 aromatic compounds containing three aldehyde groups.

6. The perovskite solar cell according to claim 5, characterized in that, The concentration of trialdehyde-resorcinol in the solution is 8-12 mmol / L; And / or, solvent A in the solution containing trialdehyde resorcinol includes chloroform; And / or, the concentration of p-phenylenediamine in the solution containing p-phenylenediamine is 60-70 mmol / L; And / or, solvent B in the p-phenylenediamine-containing solution includes ethanol; And / or, the molar ratio of the trialdehyde phloroglucinol to p-phenylenediamine is 1:(8-12); And / or, the trialdehyde compound is selected from at least one of pyromellitic pyromellitic aldehyde, 2-hydroxy-1,3,5-phenyltrialdehyde, 2,4-dihydroxy-1,3,5-pyromellitic pyromellitic aldehyde or trialdehyde-resorcinol; And / or, the molar ratio of the intermediate to the trialdehyde compound is 1:(0.8-1.2); And / or, the reaction in step (1) is carried out at a temperature of 60-70°C for 1-2 hours; And / or, the reaction in step (2) is carried out in the presence of solvent C, which includes any one or a combination of at least two of the following: mesitylene, 1,4-dioxane, acetic acid, n-butanol, o-dichlorobenzene or deionized water; And / or, the reaction in step (2) is carried out at a temperature of 110-130°C for 2-4 days.

7. The perovskite solar cell according to claim 1, characterized in that, The thickness of the interface passivation layer is 20-100 nm; And / or, the thickness of the perovskite light-absorbing layer is 300-700 nm; And / or, the first carrier transport layer is a hole transport layer and the second carrier transport layer is an electron transport layer; or, the first carrier transport layer is an electron transport layer and the second carrier transport layer is a hole transport layer.

8. A method for preparing a perovskite solar cell according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: A first carrier transport layer, a perovskite light-absorbing layer, an interface passivation layer, a second carrier transport layer, and an electrode layer are disposed on one side of the substrate to obtain the perovskite solar cell.

9. The preparation method according to claim 8, characterized in that, The method for setting the interface passivation layer includes the following steps: The interface passivation material precursor solution is coated on the side of the perovskite light-absorbing layer away from the first carrier transport layer, and then annealed to obtain the interface passivation layer. The interface passivation material precursor solution includes the COFs material as described in claim 1.

10. The preparation method according to claim 9, characterized in that, The interface passivation material precursor solution was prepared by the following method, which includes the following steps: The COFs material and solvent D are mixed to obtain the interface passivation material precursor solution; The solvent D includes any one or a combination of at least two of isopropanol, ethanol, butanol, methanol, or acetone; The concentration of COFs material in the interface passivation material precursor solution is 1-5 mg / mL; The annealing temperature is 70-90℃ and the time is 4-8 min.

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