Modified metal organic framework material, solar cell and preparation method and application thereof

Abstract

The invention relates to a modified metal organic framework material, a solar cell and a preparation method and application thereof. The modified metal organic framework material comprises metal ions, terephthalic acid and tetra (4-pyridyl) tetrathiafulvalene, wherein the terephthalic acid and the tetra (4-pyridyl) tetrathiafulvalene are in coordination connection with the metal ions, and the modified metal organic framework material has an MIL-101 skeleton structure. The modified metal organic framework material can be applied to a perovskite solar cell, the stability, crystallinity and passivation performance of the perovskite solar cell are improved, and then the photoelectric conversion efficiency of the solar cell is improved.

Description

Technical Field

[0001] This application relates to the field of solar cells, and in particular to a modified metal-organic framework material, a solar cell, its preparation method, and its applications. Background Technology

[0002] In recent years, perovskite solar cells have developed rapidly due to their advantages such as high light absorption coefficient, low cost, and ease of fabrication. However, perovskite solar cells still suffer from problems such as poor stability, poor passivation performance, and poor crystallinity, which affect the improvement of photoelectric conversion efficiency and limit their application.

[0003] Metal-organic framework materials are widely used in perovskite solar cells due to their high porosity and ultra-high specific surface area. However, the application of traditional metal-organic framework materials in solar cells has limited effect on improving the photoelectric conversion efficiency of solar cells. Summary of the Invention

[0004] Based on this, some embodiments of this application provide a modified metal-organic framework material that can be applied in perovskite solar cells to improve their stability, crystallinity and passivation properties, thereby improving the photoelectric conversion efficiency of the solar cells.

[0005] In addition, some other embodiments of this application also provide a method for preparing a modified metal-organic framework material, its application, a solar cell and its preparation method, and a photovoltaic module.

[0006] A modified metal-organic framework material comprises: a metal ion and terephthalic acid and tetra(4-pyridyl)tetrathiofulvalene, both coordinated to the metal ion, wherein the modified metal-organic framework material has a MIL-101 framework structure.

[0007] In some embodiments, the molar ratio of the terephthalic acid to the tetra(4-pyridyl)tetrathiofulvalene is (1~32):1.

[0008] In some embodiments, the molar ratio of the terephthalic acid to the tetra(4-pyridyl)tetrathiofulvalene is (16~32):1.

[0009] In some embodiments, the metal ions include one or both of chromium ions and iron ions.

[0010] In some embodiments, the modified metal-organic framework material has a specific surface area of ​​2300 m². 2 / g~4100m 2 / g.

[0011] In some embodiments, the modified metal-organic framework material has a specific surface area of ​​3900 m². 2 / g~4100m2 / g.

[0012] In some embodiments, the modified metal-organic framework material has a pore volume of 1.6 cm³. 3 / g~1.9cm 3 / g.

[0013] In some embodiments, the modified metal-organic framework material has a pore volume of 1.75 cm³. 3 / g~1.85cm 3 / g.

[0014] A method for preparing a modified metal-organic framework material includes the following steps:

[0015] A modified metal-organic framework material with the MIL-101 framework structure was prepared by coordinating a metal salt, terephthalic acid, and tetra(4-pyridyl)tetrathiofulvalene to achieve coordination linkage between the metal ion, terephthalic acid, and tetra(4-pyridyl)tetrathiofulvalene.

[0016] In some embodiments, the coordination reaction is carried out at a temperature of 175°C to 195°C for a reaction time of 18h to 24h.

[0017] In some embodiments, a basic reagent and water are added to the coordination reaction step, and the molar ratio of the metal salt, the basic reagent, the terephthalic acid, the tetra(4-pyridyl)tetrathiofulvalene and water is (0.5~2):(0.5~2):(1~32):1:(278~300).

[0018] Applications of the modified metal-organic framework materials described above, or the modified metal-organic framework materials prepared by the methods described above, in the fabrication of solar cells.

[0019] A solar cell includes: a perovskite layer, a dielectric layer, and a hole transport layer, wherein the dielectric layer is disposed between the perovskite layer and the hole transport layer;

[0020] The material of the dielectric layer includes the modified metal-organic framework material described above or the modified metal-organic framework material prepared by the preparation method described above.

[0021] In some embodiments, the thickness of the dielectric layer is 15nm to 35nm.

[0022] In some embodiments, the thickness of the hole transport layer is 15nm to 20nm.

[0023] In some embodiments, the hole transport layer is made of NiO. x And one or two of Cu2O.

[0024] In some embodiments, the thickness of the perovskite layer is 1000 nm to 1200 nm.

[0025] In some embodiments, the material of the perovskite layer includes one or more of MAPbI3, MAPbCl3, and MAPbBr3.

[0026] In some embodiments, the solar cell further includes a transparent conductive substrate, an electron transport layer, a positive electrode, and a negative electrode. The hole transport layer, the dielectric layer, the perovskite layer, and the electron transport layer are sequentially stacked on the surface of the transparent conductive substrate. The positive electrode forms an ohmic contact with the transparent conductive substrate, and the negative electrode forms an ohmic contact with the electron transport layer.

[0027] In some embodiments, the material of the electron transport layer includes one or both of TiO2 and SnO2.

[0028] In some embodiments, the thickness of the electron transport layer is 20 nm to 40 nm.

[0029] In some embodiments, the thickness of the positive electrode and the negative electrode are each independently 200 nm to 300 nm.

[0030] A method for fabricating a solar cell includes the following steps:

[0031] A dielectric layer is formed between the perovskite layer and the hole transport layer to fabricate a solar cell;

[0032] The material of the dielectric layer includes the modified metal-organic framework material described above or the modified metal-organic framework material prepared by the preparation method described above.

[0033] In some embodiments, the preparation steps of the dielectric layer include: applying a solution containing the modified metal-organic framework material to the surface of the hole transport layer and annealing it at 100°C to 150°C for 8 min to 20 min.

[0034] A photovoltaic module includes an encapsulation structure and the solar cell described above, or includes a solar cell prepared by the preparation method described above, wherein the solar cell is encapsulated by the encapsulation structure.

[0035] MIL-101 is a metal-organic framework material comprising metal ions and terephthalic acid coordinated with the metal ions. It is widely used in perovskite solar cells due to its high porosity and ultra-high specific surface area. Its interaction with perovskite promotes the nucleation and growth of perovskite crystals, improving crystallinity and thus enhancing the conversion efficiency of perovskite solar cells. However, the applicant's research found that MIL-101 has poor water stability, and its structure is prone to collapse in humid and hot environments, affecting its performance.

[0036] Based on this, some embodiments of this application provide a modified metal-organic framework material, comprising metal ions and terephthalic acid and tetra(4-pyridyl)tetrathiofulvalene (TTF(4-Py)4) coordinated to the metal ions, possessing the framework structure of MIL-101, thus retaining the abundant microporous structure and high specific surface area of ​​MIL-101. TTF(4-Py)4, as a modified material, exhibits certain hydrophobicity, and since it contains S and N atoms, its modified metal-organic framework material, when applied in solar cells, can effectively interact with metal ions such as Pb in the perovskite layer. 2+ In combination, it passivates interface defects, reduces interface defect density, and enhances passivation performance. Simultaneously, it promotes the nucleation and crystallization process of perovskite films, increasing the crystallinity of the perovskite layer. Furthermore, due to the hydrophobicity of TTF(4-Py)4, it improves the stability of perovskite solar cells to some extent. In addition, the modified metal-organic framework material is a porous material with a large number of micropores, which does not affect hole transport.

[0037] Therefore, the modified metal-organic framework materials mentioned above can be applied to perovskite solar cells to improve their stability, crystallinity, and passivation properties, thereby improving the photoelectric conversion efficiency of the solar cells. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of a solar cell according to some embodiments of this application;

[0040] Figure 2 XRD patterns of the modified metal-organic framework materials prepared in each synthesis example;

[0041] Figure 3 SEM image of the modified metal-organic framework material prepared in Example 4. Detailed Implementation

[0042] To facilitate understanding of this application, a more comprehensive description of the application will be provided below in conjunction with specific embodiments. Preferred embodiments of the application are given in the specific embodiments. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0044] Unless otherwise stated or in case of conflict, the terms or phrases used in this application shall have the following meanings:

[0045] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features.

[0046] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0047] In this application, "one or more" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0048] In this document, terms such as "further," "even further," "especially," "for example," "as," "example," and "exemplary" are used for descriptive purposes to indicate a connection in the coverage of different technical solutions presented earlier and later. However, they should not be construed as limitations on the preceding technical solution or on the scope of protection of this document. Unless otherwise specified, A (as in B) indicates that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0049] In this document, "optionally," "optionally," and "optional" mean that something is optional, that is, it is selected from either "present" or "absent." If multiple "options" appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "option" is independent. In this application, descriptions such as "optionally contains" and "optionally includes" indicate "contains or does not contain." "Optional component X" indicates whether component X exists or does not exist, or whether component X is contained or not.

[0050] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed in this application should be understood to include any and all subranges to which they are included.

[0051] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0052] The terms "comprising" and "having," and any variations thereof, used in the embodiments of this application, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to such processes, methods, products, or devices.

[0053] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0054] Traditional perovskite solar cells typically consist of a positive electrode, a transparent conductive substrate, a hole transport layer, a perovskite layer, an electron transport layer, and a negative electrode. Currently, perovskite solar cells still suffer from the following problems: they are unstable and easily decompose in humid and hot environments; the interface defect density between the perovskite layer and the hole transport layer is high, resulting in poor passivation performance and relatively poor crystallinity.

[0055] Based on this, this application provides a modified metal-organic framework material that can be applied between the perovskite layer and the hole transport layer to improve the stability, passivation performance and crystallinity of solar cells, thereby improving their photoelectric conversion efficiency.

[0056] In a first aspect, this application provides a modified metal-organic framework material comprising: a metal ion and terephthalic acid and tetra(4-pyridyl)tetrathiofulvalene, both coordinated to the metal ion, wherein the modified metal-organic framework material has a MIL-101 framework structure.

[0057] Terephthalic acid is abbreviated as H2BDC. Tetra(4-pyridyl)tetrathiofulvalene, abbreviated as TTF(4-Py)4, has the following structural formula: .

[0058] The aforementioned modified metal-organic framework material comprises metal ions and terephthalic acid and tetra(4-pyridyl)tetrathiofulvalene coordinated with the metal ions, possessing a MIL-101 framework structure, resulting in a large number of micropores with excellent pore volume and good gas transport channels. TTF(4-Py)4, as a modifying material, exhibits certain hydrophobicity and contains S and N atoms. Applying this modified metal-organic framework material to solar cells can effectively bind with metal ions such as Pb in the perovskite layer. 2+ The combination of these components significantly reduces recombination in perovskite solar cells, passivates interface defects, reduces defect density, and enhances passivation performance. It also lowers the activation energy required for perovskite layer crystallization, promoting nucleation and growth of the perovskite film and increasing its crystallinity. Furthermore, the hydrophobicity of TTF(4-Py)4 contributes to improved stability of the perovskite solar cells. Additionally, the modified metal-organic framework material, being a porous material with numerous micropores, does not affect hole transport.

[0059] Therefore, the modified metal-organic framework materials mentioned above can be applied to perovskite solar cells to improve their stability, crystallinity, and passivation properties, thereby improving the photoelectric conversion efficiency of the solar cells.

[0060] In some embodiments, in the modified metal-organic framework material, metal ions are coordinated with the O group of the carboxyl group of terephthalic acid and the N group of TTF(4-Py)4, respectively, thereby bridging each other. This modified metal-organic framework material has a MIL-101 framework structure, possessing a large number of micropores, excellent pore volume, and good gas transport channels.

[0061] MIL-101 is a metal-organic framework material composed of metal ions and terephthalic acid coordinated with the metal ions. It has an ultra-high specific surface area, is predominantly microporous with a very small number of mesoporous structures, and its porosity is easily tunable. However, MIL-101 is highly hydrophilic, mainly due to its weak metal-oxygen coordination, making it easily attacked by hydroxyl groups in water molecules, causing the framework structure to collapse. In some embodiments of this application, it is modified with TTF(4-Py)4. TTF(4-Py)4 has a certain degree of hydrophobicity and contains S and N atoms, which can coordinate with metal ions, thus improving its stability while retaining the framework structure of MIL-101.

[0062] In some embodiments, the molar ratio of TTF(4-Py)4 to terephthalic acid is 1:(1~32). For example, the molar ratio of TTF(4-Py)4 to terephthalic acid may be, but is not limited to, 1:1, 1:2, 1:4, 1:8, 1:10, 1:12, 1:16, 1:18, 1:20, 1:24, 1:28, 1:32, or any range of these values. Optionally, the molar ratio of TTF(4-Py)4 to terephthalic acid is 1:(8~32). Optionally, the molar ratio of TTF(4-Py)4 to terephthalic acid is 1:(16~32). In a specific example, the molar ratio of TTF(4-Py)4 to terephthalic acid is 1:16. Because TTF(4-Py)4 has a more complex structure and longer side chains than terephthalic acid, it can cause partial pore blockage in MIL-101. Optimizing the amount of TTF(4-Py)4 and terephthalic acid can help to further improve the photoelectric conversion efficiency of solar cells.

[0063] In some embodiments, the metal ions include one or both of chromium ions and iron ions.

[0064] In some embodiments, the specific surface area of ​​the modified metal-organic framework material is 2300 m². 2 / g~4100m 2 / g. For example, the specific surface area of ​​modified organic framework materials can be, but is not limited to, 2300 m². 2 / g、2500m 2 / g、2800m 2 / g、3000m 2 / g、3200m 2 / g、3500m 2 / g、3800m 2 / g、3900m 2 / g、3950m 2 / g、4000m 2 / g、4050m 2 / g、4100m2 / g or a range consisting of any two of these values. Optionally, the specific surface area of ​​the modified metal-organic framework material is 3500 m². 2 / g~4100m 2 / g. Optionally, the specific surface area of ​​the modified metal-organic framework material is 3900 m². 2 / g~4100m 2 / g.

[0065] In some embodiments, the pore volume of the modified metal-organic framework material is 1.3 cm³. 3 / g~1.9cm 3 / g. For example, the pore volume of modified metal-organic framework materials can be, but is not limited to, 1.3 cm³. 3 / g, 1.5cm 3 / g, 1.6cm 3 / g, 1.65cm 3 / g, 1.7cm 3 / g, 1.75cm 3 / g, 1.8cm 3 / g, 1.85cm 3 / g, 1.9cm 3 / g or a range consisting of any two of these values. Optionally, the pore volume of the modified metal-organic framework material is 1.6 cm³. 3 / g~1.85cm 3 / g. Optionally, the pore volume of the modified metal-organic framework material is 1.75 cm³. 3 / g~1.85cm 3 / g.

[0066] Secondly, this application provides a method for preparing a modified metal-organic framework material, comprising the following steps:

[0067] A modified metal-organic framework material with the MIL-101 framework structure was prepared by coordinating a metal salt, terephthalic acid, and tetra(4-pyridyl)tetrathiofulvalene to achieve coordination linkage between the metal ion, terephthalic acid, and tetra(4-pyridyl)tetrathiofulvalene.

[0068] In some embodiments, the coordination reaction temperature is 175°C to 195°C, and the reaction time is 18h to 24h. The coordination reaction temperature can be, but is not limited to, 175°C, 176°C, 178°C, 180°C, 182°C, 185°C, 186°C, 188°C, 190°C, 192°C, 195°C, or any combination of these values. Adjusting the coordination reaction temperature within the above range helps to ensure better crystallinity and grain shape, resulting in better hole transport performance when used in solar cells. The coordination reaction time can be, but is not limited to, 18h, 19h, 20h, 21h, 22h, 23h, 24h, or any combination of these values.

[0069] In some embodiments, the molar ratio of terephthalic acid to tetra(4-pyridyl)tetrathiofulvalene is (1~32):1.

[0070] In some embodiments, the molar ratio of the metal salt to TTF(4-Py)4 is (0.5~2):1. In a specific example, the molar ratio of the metal salt to TTF(4-Py)4 is 1:1.

[0071] In some embodiments, the metal salt includes one or both of chromium and iron salts. Specifically, the metal salt includes chromium nitrate, such as chromium nitrate nonahydrate.

[0072] In some embodiments, an alkaline reagent and water are also added during the coordination reaction step.

[0073] Specifically, the molar ratio of the alkaline reagent to TTF(4-Py)4 is (0.5~2):1. In a specific example, the molar ratio of the alkaline reagent to TTF(4-Py)4 is 1:1. Specifically, the alkaline reagent includes sodium hydroxide.

[0074] Specifically, the molar ratio of water to TTF(4-Py)4 is (278~300):1.

[0075] In some embodiments, the molar ratio of the metal salt, basic reagent, terephthalic acid, TTF(4-Py)4, and water is (0.5~2):(0.5~2):(1~32):1:(278~300). In one specific example, the molar ratio of the metal salt, basic reagent, terephthalic acid, TTF(4-Py)4, and water is 1:1:(1~32):1:(278~300).

[0076] In a specific example, the coordination reaction takes place in a closed reactor. For instance, the coordination reaction is carried out in a closed polytetrafluoroethylene reactor. Due to the high temperature of the coordination reaction, water vapor generates pressure under high-temperature conditions, creating a certain high-pressure condition.

[0077] In some embodiments, a purification step is included after the coordination reaction. Specifically, N,N-dimethylformamide and hot ethanol are added to the reaction system, followed by filtration, washing, and drying. The washing is performed with distilled water and ethanol, respectively. Specifically, the temperature of the hot ethanol is 60°C to 80°C. After the reaction, the pores of the prepared modified metal-organic framework material contain unreacted ligands that block the pores; therefore, purification is required to remove the unreacted ligands using N,N-dimethylformamide and hot ethanol.

[0078] In some embodiments, the preparation steps of the modified metal-organic framework material include:

[0079] Step S110: Mix the metal salt, alkaline reagent, terephthalic acid, TTF(4-Py)4 and water to prepare a precursor solution.

[0080] Step S120: The precursor solution is subjected to a coordination reaction at 175℃~195℃ for 18h~24h.

[0081] Step S130: Add N,N-dimethylformamide and hot ethanol to the reaction system, filter, wash, dry, and prepare the modified metal-organic framework material.

[0082] Thirdly, this application provides the application of the modified metal-organic framework material of the first aspect above or the modified metal-organic framework material prepared by the preparation method of the second aspect above in the preparation of solar cells.

[0083] The aforementioned modified metal-organic framework material comprises metal ions and terephthalic acid and tetra(4-pyridyl)tetrathiofulvalene coordinated with the metal ions, possessing a MIL-101 framework structure, resulting in a large number of micropores, excellent pore volume, and good gas transport channels. TTF(4-Py)4, as a modifying material, exhibits certain hydrophobicity and contains S and N atoms. Applying this modified metal-organic framework material in solar cells can effectively bind with metal ions such as Pb in the perovskite layer. 2+ The combination of these components significantly reduces recombination in perovskite solar cells, passivates interface defects, reduces defect density, and enhances passivation performance. It also lowers the activation energy required for perovskite layer crystallization, promoting nucleation and growth of the perovskite film and increasing its crystallinity. Furthermore, the hydrophobicity of TTF(4-Py)4 contributes to improved stability of the perovskite solar cells. Additionally, the modified metal-organic framework material, being a porous material with numerous micropores, does not affect hole transport.

[0084] Therefore, the modified metal-organic framework materials mentioned above can be applied to perovskite solar cells to improve their stability, crystallinity, and passivation properties, thereby improving the photoelectric conversion efficiency of the solar cells.

[0085] Fourthly, this application provides a solar cell including a perovskite layer, a dielectric layer, and a hole transport layer, wherein the dielectric layer is disposed between the perovskite layer and the hole transport layer.

[0086] The material of the dielectric layer includes the modified metal-organic framework material of the first aspect or the modified metal-organic framework material prepared by the preparation method of the second aspect.

[0087] The dielectric layer has a certain degree of hydrophobicity, which can enhance the stability of perovskite solar cells and reduce the activation energy required for perovskite layer crystallization, thus promoting perovskite crystallization. The defect density at the interface between the perovskite and hole transport layers is relatively large. The dielectric layer is located between the perovskite and hole transport layers and can serve as an effective passivation layer. Furthermore, the S and N in the TTF(4-Py)4 ligands of the dielectric layer can combine with the free metal elements in the perovskite layer, greatly reducing the recombination of perovskite solar cells and thereby improving the efficiency of perovskite solar cells.

[0088] Through relevant tests, the introduction of this dielectric layer improved the conversion efficiency of perovskite solar cells by more than 0.2% and greatly enhanced the passivation performance.

[0089] In some embodiments, the thickness of the dielectric layer is 15 nm to 35 nm. For example, the thickness of the dielectric layer can be, but is not limited to, 15 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 25 nm, 26 nm, 28 nm, 30 nm, 32 nm, 35 nm, or any combination of these values. If the thickness of the dielectric layer is too small, the improvement in the photoelectric conversion efficiency of the solar cell is limited; if the thickness of the dielectric layer is too large, it will increase parasitic absorption of light in the dielectric layer, thereby reducing the short-circuit current.

[0090] In some embodiments, the thickness of the perovskite layer is 1000 nm to 1200 nm. For example, the thickness of the perovskite layer may be, but is not limited to, 1000 nm, 1020 nm, 1050 nm, 1080 nm, 1100 nm, 1120 nm, 1150 nm, 1180 nm, 1200 nm, or any combination of these values.

[0091] In some embodiments, the perovskite layer material includes one or more of MAPbI3, MAPbCl3, and MAPbBr3.

[0092] In some embodiments, the thickness of the hole transport layer is 15 nm to 20 nm. For example, the thickness of the hole transport layer may be, but is not limited to, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, or any combination of these values.

[0093] In some embodiments, the hole transport layer is made of NiO. x And one or two of Cu2O.

[0094] In some embodiments, the solar cell is a single-junction cell; specifically, please refer to [link to relevant documentation]. Figure 1 The solar cell 200 includes: a transparent conductive substrate 210, a hole transport layer 220, a dielectric layer 230, a perovskite layer 240, an electron transport layer 250, a positive electrode 260, and a negative electrode 270. The hole transport layer 220, dielectric layer 230, perovskite layer 240, and electron transport layer 250 are sequentially stacked on the surface of the transparent conductive substrate 210. The positive electrode 260 forms an ohmic contact with the transparent conductive substrate 210, and the negative electrode 270 forms an ohmic contact with the electron transport layer 250.

[0095] In some embodiments, the thickness of the transparent conductive substrate is 800 nm to 1000 nm. For example, the thickness of the transparent conductive substrate may be, but is not limited to, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm or any combination of these values.

[0096] In some embodiments, the material of the transparent conductive substrate includes one or more of indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), indium-doped zinc oxide (IZO), and fluorine-doped tin oxide (FTO).

[0097] In some embodiments, the thickness of the electron transport layer is 20 nm to 40 nm. For example, the thickness of the electron transport layer may be, but is not limited to, 20 nm, 22 nm, 24 nm, 25 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 35 nm, 36 nm, 38 nm, 40 nm, or any combination of these values.

[0098] In some embodiments, the material of the electron transport layer includes one or both of TiO2 and SnO2.

[0099] In some embodiments, the thickness of the positive electrode and the negative electrode are each independently between 200 nm and 300 nm. For example, the thickness of the positive electrode and the negative electrode are each independently 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, or any combination of these values. It is understood that the thickness of the positive electrode and the negative electrode can be the same or different, and there is no particular limitation.

[0100] In some embodiments, the positive electrode and the negative electrode are each independently a metal electrode. It is understood that the materials of the positive electrode and the negative electrode can be the same or different.

[0101] It is understandable that the above only lists some of the more common materials and their common thicknesses in each layer, but is not limited to these.

[0102] It is understood that in some other embodiments, the solar cell may also be a tandem cell. Specifically, the solar cell includes: a base cell, a hole transport layer, a perovskite layer, a dielectric layer, an electron transport layer, a positive electrode, and a negative electrode; wherein the hole transport layer, the dielectric layer, the perovskite layer, and the electron transport layer are sequentially stacked on the surface of the base cell, the positive electrode forms an ohmic contact with the base cell, and the negative electrode forms an ohmic contact with the electron transport layer.

[0103] When the solar cell is a tandem cell, the bottom electrode can be, for example, but is not limited to, a silicon cell. The materials and thicknesses of the hole transport layer, perovskite layer, electron transport layer, positive electrode, and negative electrode are the same as those for a single-junction solar cell, and will not be repeated here.

[0104] Fifthly, this application provides a method for fabricating a solar cell, comprising the following steps:

[0105] A dielectric layer is formed between a perovskite layer and a hole transport layer to fabricate a solar cell. The material of the dielectric layer includes the modified metal-organic framework material described in the first aspect or the modified metal-organic framework material prepared by the preparation method described in the second aspect.

[0106] In some embodiments, the preparation step of the dielectric layer includes: applying a solution containing a modified metal-organic framework material to the surface of the hole transport layer and annealing it at 100°C to 150°C for 8 min to 20 min.

[0107] In one example, the annealing temperature may be, but is not limited to, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, or any combination of these values. The annealing time may be, but is not limited to, 8 min, 10 min, 12 min, 14 min, 15 min, 16 min, 18 min, 20 min, or any combination of these values.

[0108] In some embodiments, the solvent in the solution containing the modified metal-organic framework material includes one or more of ethanol (CH3CH2OH), dichloromethane, and toluene.

[0109] In some embodiments, a solution containing a modified metal-organic framework material is applied to the surface of the hole transport layer using spin coating. Specifically, the spin coating speed is 4000 rpm to 6000 rpm, and the spin coating time is 15 s to 30 s. For example, the spin coating speed can be, but is not limited to, 4000 rpm, 4200 rpm, 4500 rpm, 4800 rpm, 5000 rpm, 5200 rpm, 5500 rpm, 5800 rpm, 6000 rpm, or any combination of these values. The spin coating time can be, but is not limited to, 15 s, 18 s, 20 s, 22 s, 25 s, 28 s, 30 s, or any combination of these values. Furthermore, during the spin coating process, the ambient humidity is 5% to 10%.

[0110] In some embodiments, the step of forming a dielectric layer between the perovskite layer and the hole transport layer includes: spin-coating a solution containing a modified metal-organic framework material onto the surface of the hole transport layer under ambient humidity of 5% to 10%, with a spin-coating speed of 4000 rpm to 6000 rpm and a spin-coating time of 15 to 30 seconds, followed by annealing at 100°C to 150°C for 8 to 20 minutes to form a dielectric layer with a thickness of 15 nm to 35 nm.

[0111] In some embodiments, the solar cell is a single-junction cell, such as... Figure 1 As shown, the solar cell 200 includes: a transparent conductive substrate 210, a hole transport layer 220, a dielectric layer 230, a perovskite layer 240, an electron transport layer 250, a positive electrode 260, and a negative electrode 270. The hole transport layer 220, dielectric layer 230, perovskite layer 240, and electron transport layer 250 are sequentially stacked on the surface of the transparent conductive substrate 210. The positive electrode 260 forms an ohmic contact with the transparent conductive substrate 210, and the negative electrode 270 forms an ohmic contact with the electron transport layer 250.

[0112] At this point, the method for fabricating solar cells includes the following steps:

[0113] Step S310: Form a hole transport layer on a transparent conductive substrate.

[0114] Step S320: A dielectric layer is formed on the surface of the hole transport layer away from the transparent conductive substrate.

[0115] Step S330: A perovskite layer is formed on the surface of the dielectric layer away from the transparent conductive substrate.

[0116] Step S340: An electron transport layer is formed on the surface of the perovskite layer away from the transparent conductive substrate.

[0117] Step S350: Form a negative electrode on the side of the electron transport layer away from the transparent conductive substrate.

[0118] Step S360: Form a positive electrode on the surface of the transparent conductive substrate away from the hole transport layer to prepare a solar cell.

[0119] In some embodiments, a transparent conductive substrate is prepared using magnetron sputtering. Specifically, a PVD (physical vapor deposition) apparatus is used to form the transparent conductive substrate.

[0120] In some embodiments, the hole transport layer is formed by vapor deposition. Specifically, a PVD (physical vapor deposition) device is used to form the hole transport layer.

[0121] In some embodiments, a solution method is used to form the perovskite layer.

[0122] In some embodiments, the electron transport layer is formed using plasma deposition. Specifically, an RPD (Reactive Plasma Deposition) device is used to form the electron transport layer.

[0123] In some embodiments, the positive and negative electrodes are formed by vapor deposition. For example, vapor deposition is performed in a vapor deposition apparatus.

[0124] The specific preparation processes for each of the above layers can be obtained based on conventional knowledge in this field, and are not specifically limited here.

[0125] It is understood that in some other embodiments, the solar cell may also be a tandem cell, and the preparation method of the solar cell can refer to the above, and will not be repeated here.

[0126] Sixthly, this application provides a photovoltaic module, including an encapsulation structure and the solar cell described above, or including a solar cell prepared by the preparation method described above, wherein the solar cell is encapsulated by the encapsulation structure.

[0127] The packaging structure includes the packaging frame.

[0128] In some embodiments, the photovoltaic module further includes photovoltaic glass and a photovoltaic backsheet. The photovoltaic glass is disposed on the upper surface of the solar cell to protect the solar cell. The photovoltaic backsheet is disposed on the lower surface of the solar cell to further protect the cell. The photovoltaic glass and the solar cell, and the photovoltaic backsheet and the solar cell, are connected by an encapsulating film.

[0129] It is understandable that the photovoltaic backsheet set on the lower surface of the solar cell can also be replaced by photovoltaic glass.

[0130] To make the objectives and advantages of this application clearer, the modified metal-organic framework material, solar cell, and their effects described below are further explained in detail with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining this application and should not be used to limit this application. Unless otherwise specified, the following embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the drugs and instruments used in the embodiments are conventional choices in the art. Experimental methods in the embodiments that do not specify specific conditions were implemented according to conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0131] Synthesis Example 1

[0132] This synthetic example provides a modified metal-organic framework material, and the preparation steps are as follows:

[0133] (1) Mix 2g of chromium nitrate nonahydrate, 0.2g of sodium hydroxide, 0.83g of terephthalic acid, 2.56g of TTF(4-Py)4 (the molar ratio of TTF(4-Py)4 to terephthalic acid is 1:1) and 25mL of deionized water evenly, stir and sonicate at room temperature to obtain precursor solution A.

[0134] (2) Pour the precursor solution A into a polytetrafluoroethylene hydrothermal reactor, seal it, and place it in an oven at 185°C for 24 hours to obtain unpurified TTF(4-Py)4 modified MIL-101 metal-organic framework material.

[0135] (3) The obtained unpurified TTF(4-Py)4 modified MIL-101 metal-organic framework material was added to a mixed solvent of N,N-dimethylformamide and hot ethanol for purification to obtain purified TTF(4-Py)4 modified MIL-101 metal-organic framework material.

[0136] (4) The purified TTF(4-Py)4 modified MIL-101 metal-organic framework material was washed with distilled water and ethanol and dried to obtain the modified metal-organic framework material of this synthesis example.

[0137] Synthesis Example 2

[0138] This synthesis example provides a modified metal-organic framework material. The preparation steps are basically the same as those in synthesis example 1, except that the molar ratio of TTF(4-Py)4 to terephthalic acid is different in step (1). In this synthesis example, the molar ratio of TTF(4-Py)4 to terephthalic acid is 1:4. Step (1) of this synthesis example is as follows:

[0139] (1) Mix 0.64g TTF(4-Py)4, 2g chromium nitrate nonahydrate, 0.2g sodium hydroxide, 0.83g terephthalic acid and 25mL deionized water and sonicate to obtain precursor solution A.

[0140] The other steps are the same as in Example 1 of the synthesis, and will not be repeated here.

[0141] Synthesis Example 3

[0142] This synthesis example provides a modified metal-organic framework material. The preparation steps are basically the same as those in synthesis example 1, except that the molar ratio of TTF(4-Py)4 to terephthalic acid is different in step (1). In this synthesis example, the molar ratio of TTF(4-Py)4 to terephthalic acid is 1:8. Step (1) of this synthesis example is as follows:

[0143] (1) Mix 0.32g TTF(4-Py)4, 2g chromium nitrate nonahydrate, 0.2g sodium hydroxide, 0.83g terephthalic acid and 25mL deionized water and sonicate to obtain precursor solution A.

[0144] The other steps are the same as in Example 1 of the synthesis, and will not be repeated here.

[0145] Synthesis Example 4

[0146] This synthesis example provides a modified metal-organic framework material. The preparation steps are basically the same as those in synthesis example 1, except that the molar ratio of TTF(4-Py)4 to terephthalic acid is different in step (1). In this synthesis example, the molar ratio of TTF(4-Py)4 to terephthalic acid is 1:16. Step (1) of this synthesis example is as follows:

[0147] (1) Mix 0.16g TTF(4-Py)4, 2g chromium nitrate nonahydrate, 0.2g sodium hydroxide, 0.83g terephthalic acid and 25mL deionized water and sonicate to obtain precursor solution A.

[0148] The other steps are the same as in Example 1 of the synthesis, and will not be repeated here.

[0149] Synthesis Example 5

[0150] This synthesis example provides a modified metal-organic framework material. The preparation steps are basically the same as those in synthesis example 1, except that the molar ratio of TTF(4-Py)4 to terephthalic acid is different in step (1). In this synthesis example, the molar ratio of TTF(4-Py)4 to terephthalic acid is 1:32. Step (1) of this synthesis example is as follows:

[0151] (1) Mix 0.08g TTF(4-Py)4, 2g chromium nitrate nonahydrate, 0.2g sodium hydroxide, 0.83g terephthalic acid and 25mL deionized water and sonicate to obtain precursor solution A.

[0152] The other steps are the same as in Example 1 of the synthesis, and will not be repeated here.

[0153] Synthetic Comparative Example 1

[0154] Comparative Example 1 provides a MIL-101 metal-organic framework, and the preparation steps are basically the same as those in Comparative Example 1, except that TTF(4-Py)4 was not added in step (1). Step (1) of Comparative Example 1 is as follows:

[0155] 2g of chromium nitrate nonahydrate, 0.2g of sodium hydroxide, 0.83g of terephthalic acid and 25mL of deionized water were mixed and sonicated to obtain precursor solution A.

[0156] Synthetic Comparative Example 2

[0157] Comparative Example 2 provides a modified metal-organic framework material. The preparation steps are similar to those in Comparative Example 1, except that terephthalic acid was not added in step (1). Step (1) of Comparative Example 2 is as follows:

[0158] (1) Mix 2g of chromium nitrate nonahydrate, 0.2g of sodium hydroxide, 2.56g of TTF(4-Py)4 and 25mL of deionized water evenly, stir and sonicate at room temperature to obtain precursor solution A.

[0159] Device Example 1

[0160] This embodiment of the device provides a solar cell, including a transparent conductive substrate, a hole transport layer, a dielectric layer, a perovskite layer, an electron transport layer, a positive electrode, and a negative electrode. The hole transport layer, the dielectric layer, the perovskite layer, and the electron transport layer are sequentially stacked on the surface of the transparent conductive substrate. The positive electrode forms an ohmic contact with the transparent conductive substrate, and the negative electrode forms an ohmic contact with the electron transport layer.

[0161] The fabrication steps of a solar cell are as follows:

[0162] (1) Using a PVD device, ITO was deposited on the substrate surface by magnetron sputtering to obtain a transparent conductive substrate with a thickness of 900 nm.

[0163] (2) Using PVD equipment, Cu2O was deposited on the surface of a transparent conductive substrate by vapor deposition to obtain a hole transport layer with a thickness of 18 nm.

[0164] (3) The modified metal-organic framework material prepared in Example 1 was dissolved in CH3CH2OH and coated on the hole transport layer by spin coating. Then, it was annealed in an annealing furnace at 130°C for 15 min to obtain a dielectric layer with a thickness of 25 nm.

[0165] (4) MAPbI3 is formed on the surface of the dielectric layer using a coating machine to obtain a perovskite layer with a thickness of 1100 nm.

[0166] (5) SnO2 was deposited on the surface of the perovskite layer using an RPD device to obtain an electron transport layer with a thickness of 30 nm.

[0167] (6) A negative electrode is deposited on the surface of the electron transport layer using a vapor deposition apparatus, and a positive electrode is deposited on the surface of the transparent conductive substrate to obtain a solar cell. The thickness of the positive electrode is 260 nm, and the thickness of the negative electrode is 260 nm.

[0168] Device Example 2

[0169] This device embodiment provides a solar cell similar to the solar cell in Device Embodiment 1, except that the material of the dielectric layer is different. The dielectric layer of this device embodiment uses the modified metal-organic framework material synthesized in Embodiment 2.

[0170] The preparation steps of the dielectric layer, other layers in the solar cell, and their preparation steps are the same as in Device Example 1, and will not be repeated here.

[0171] Device Example 3

[0172] This device embodiment provides a solar cell similar to the solar cell in Device Embodiment 1, except that the material of the dielectric layer is different. The dielectric layer of this device embodiment uses the modified metal-organic framework material synthesized in Embodiment 3.

[0173] The preparation steps of the dielectric layer, other layers in the solar cell, and their preparation steps are the same as in Device Example 1, and will not be repeated here.

[0174] Device Example 4

[0175] This embodiment of the device provides a solar cell, similar to the solar cell of embodiment 1, except that the material of the dielectric layer is different. The dielectric layer of this embodiment is made of the modified metal-organic framework material synthesized in embodiment 4.

[0176] The preparation steps of the dielectric layer, other layers in the solar cell, and their preparation steps are the same as in Device Example 1, and will not be repeated here.

[0177] Device Example 5

[0178] This device embodiment provides a solar cell similar to the solar cell in Device Embodiment 1, except that the dielectric layer material is different. The dielectric layer material in this device embodiment is the modified metal-organic framework material synthesized in Embodiment 5.

[0179] The preparation steps of the dielectric layer, other layers in the solar cell, and their preparation steps are the same as in Device Example 1, and will not be repeated here.

[0180] Device Comparison Example 1

[0181] Comparative Example 1 provides a solar cell similar to that of Example 1, except that the dielectric layer material is different. The dielectric layer of Comparative Example 1 is made of the MIL-101 metal-organic framework material synthesized in Comparative Example 1.

[0182] The preparation steps of the dielectric layer, other layers in the solar cell, and their preparation steps are the same as in Device Example 1, and will not be repeated here.

[0183] Device Comparison Example 2

[0184] Comparative Example 2 provides a solar cell similar to the solar cell in Device Example 1, except that the material of the dielectric layer is different. The dielectric layer of Comparative Example 2 is made of the modified metal-organic framework material synthesized in Comparative Example 2.

[0185] The preparation steps of the dielectric layer, other layers in the solar cell, and their preparation steps are the same as in Device Example 1, and will not be repeated here.

[0186] Device Comparison Example 3

[0187] Comparative Example 3 provides a solar cell that is similar to the solar cell in Device Example 1, except that it does not contain a dielectric layer. It includes a transparent conductive substrate, a hole transport layer, a perovskite layer, an electron transport layer, a positive electrode, and a negative electrode. The hole transport layer, the perovskite layer, and the electron transport layer are sequentially stacked on the surface of the transparent conductive substrate. The positive electrode forms an ohmic contact with the transparent conductive substrate, and the negative electrode forms an ohmic contact with the electron transport layer.

[0188] The fabrication steps of a solar cell are as follows:

[0189] (1) ITO was deposited by magnetron sputtering using PVD equipment to obtain a transparent conductive substrate with a thickness of 900 nm.

[0190] (2) Using PVD equipment, Cu2O was deposited on the surface of a transparent conductive substrate by vapor deposition to obtain a hole transport layer with a thickness of 18 nm.

[0191] (3) MAPbI3 was formed on the surface of the hole transport layer using a coating machine to obtain a perovskite layer with a thickness of 1100 nm.

[0192] (4) SnO2 was deposited on the surface of the perovskite layer using an RPD device to obtain an electron transport layer material with a thickness of 30 nm.

[0193] (5) A negative electrode is deposited on the surface of the electron transport layer using an evaporation apparatus, and a positive electrode is deposited on the surface of the transparent conductive substrate to obtain a solar cell. The thickness of the positive electrode is 260 nm, and the thickness of the negative electrode is 260 nm.

[0194] The following is the performance testing section:

[0195] 1. Specific surface area and pore volume testing of modified metal-organic framework materials:

[0196] The specific surface area and pore volume of the modified metal-organic framework materials prepared in the synthesis examples, the MIL-101 metal-organic framework materials prepared in the comparative synthesis examples, and the modified metal-organic framework materials were tested using an N2 adsorption-desorption instrument (model: ASAP2020, manufacturer: McMurray Instruments (Shanghai) Co., Ltd.).

[0197] The specific surface area and pore volume test data of the modified metal-organic framework materials or MIL-101 metal-organic framework materials of the above synthesis examples and comparative examples are shown in Table 1 below.

[0198] 2. XRD testing of modified metal-organic framework materials

[0199] The modified metal-organic framework materials prepared in the synthesis examples, the MIL-101 metal-organic framework materials prepared in the comparative synthesis examples, and the modified metal-organic framework materials were tested using an X-ray diffractometer (model: D8 ADVANCE, company: Bruker AXS).

[0200] The XRD test results of the modified metal-organic framework materials or MIL-101 metal-organic framework materials in the above synthesis examples and comparative examples are as follows: Figure 2 As shown.

[0201] 3. SEM testing of modified metal-organic framework materials

[0202] The modified metal-organic framework materials prepared in the synthesis examples, the MIL-101 metal-organic framework materials prepared in the comparative synthesis examples, and the modified metal-organic framework materials were tested using a field emission scanning electron microscope (model: SUPRA-55, company: ZEISS).

[0203] The SEM test results of the modified metal-organic framework materials of each of the above synthetic examples 1 are as follows: Figure 3 As shown.

[0204] 4. Tests for open-circuit voltage, short-circuit current density, and fill factor of solar cells.

[0205] The current (I)-voltage (V) of the solar cells in each device embodiment and device comparison example were measured using an IV tester (model: MX-MPVC-A20, manufacturer: Suzhou Maiwei Technology Co., Ltd.) to obtain the open-circuit voltage (V) of the solar cells. oc ), short-circuit current (J) sc ) and fill factor (FF).

[0206] 5. Photovoltaic conversion efficiency testing of solar cells

[0207] The current (I)-voltage (V) of the solar cells in each device embodiment and device comparison example were measured using an IV tester (model: MX-MPVC-A20, manufacturer: Suzhou Maiwei Technology Co., Ltd.) to obtain the photoelectric conversion efficiency (E) of the solar cells. ta ).

[0208] The V of the solar cells in the above-described device embodiments and device comparison examples oc FF, J sc and E ta The test results are shown in Table 2 below.

[0209] Table 1

[0210]

[0211] Table 2

[0212]

[0213] Figure 2 XRD patterns of the modified metal-organic framework materials prepared in each synthesis example. Figure 2 In the diagram, the horizontal axis represents 2θ (Two-Theta), in degrees (deg), and the vertical axis represents intensity. Figure 2As can be seen from the data, the modified metal-organic framework materials prepared in each embodiment all have obvious diffraction peaks on crystal planes (311), (511), (531), (882), and (911), which are consistent with the standard spectra of MIL-101. This indicates that the introduction of TTF(4-Py)4 does not change the crystal morphology. Furthermore, as the ratio of the second ligand TTF(4-Py)4 to the first ligand terephthalic acid increases, the intensity of the diffraction peaks decreases, and the number of pores occupied by the metal-organic framework also increases. In addition, since TTF(4-Py)4 is an amorphous material, it does not have special diffraction peaks. Figure 2 The diffraction peaks are not given in the text.

[0214] Figure 3 SEM images of the modified metal-organic framework material synthesized in Example 4. From Figure 3 As can be seen, the morphology of the crystal remains unchanged after modification; it is still a regular polyhedron with a relatively uniform grain distribution. However, the crystal size is smaller, about 80 nm, while the grain size of pure MIL-101 is about 200 nm. This may be due to the introduction of TTF(4-Py)4, which accelerates the nucleation rate of the crystal.

[0215] A comparison of Examples 1-5 and Comparative Example 3 shows that, compared to Comparative Example 3, the present application's method of preparing TTF(4-Py)4 modified MIL-101 metal-organic framework material between the perovskite layer and hole transport layer of the perovskite solar cell significantly improves the solar cell's conversion efficiency, while improving or approaching the performance of open-circuit voltage, short-circuit current density, and fill factor. This indicates that the preparation method of the present application can solve the problem of high interface defect density in perovskite solar cells, thereby improving the stability of perovskite solar cells and increasing photoelectric conversion efficiency, while maintaining little or no change in other performance characteristics.

[0216] The comparison of Examples 1 to 5 shows that as the ratio of the second ligand TTF(4-Py)4 to the first ligand terephthalic acid increases, the specific surface area and pore volume of the TTF(4-Py)4-modified MIL-101 metal-organic framework material decrease, and the electrical performance of the perovskite solar cell also decreases, as does the water contact angle. This is because the structure of TTF(4-Py)4 is more complex than that of terephthalic acid, with longer side chains, which can cause partial pore blockage in MIL-101. Optimizing the amount of TTF(4-Py)4 and terephthalic acid can further improve the photoelectric conversion efficiency and water contact angle of the solar cell.

[0217] As can be seen from the comparison between Examples 1-5 and Comparative Examples 1-2, compared with Comparative Examples 1 and 2, after preparing the TTF(4-Py)4 modified MIL-101 metal-organic framework material between the perovskite layer and the hole transport layer of the perovskite solar cell in this application, the E of the solar cell is significantly improved. ta Significant improvement. Compared to Comparative Example 1, the present application's embodiment, after preparing a TTF(4-Py)4-modified MIL-101 metal-organic framework material between the perovskite layer and hole transport layer of the perovskite solar cell, shows an increased water contact angle and improved stability. Furthermore, although Comparative Example 1 shows improvements in open-circuit voltage and short-circuit current density compared to Comparative Example 2, the improvement in fill factor is not significant, indicating that preparing MIL-101 only on top of the perovskite layer of the perovskite solar cell has limited impact on performance improvement. Although Comparative Example 2 shows improvements in open-circuit voltage and fill factor compared to Comparative Example 3, the improvement in short-circuit current is not significant, indicating that preparing a metal-organic framework material with TTF(4-Py)4 (without terephthalic acid ligands, i.e., without the MIL-101 framework) as a ligand only on top of the perovskite layer of the perovskite solar cell also has limited impact on performance improvement.

[0218] Therefore, the preparation method of this application first prepares a TTF(4-Py)4 modified MIL-101 metal-organic framework material. This modified metal-organic framework material contains N and S, has certain hydrophobic properties, and also has a very large specific surface area and excellent porosity. This modified metal-organic framework material is prepared between the perovskite layer and the hole transport layer of a perovskite solar cell. N and S can combine with the metal elements of the perovskite layer, effectively passivating the defects of the perovskite layer, and reducing the interface defects between the perovskite layer and the hole transport layer. Furthermore, this material can reduce the activation energy of perovskite film crystallization, promote the crystallization of the perovskite layer, and improve the water stability of the perovskite material to a certain extent, thereby significantly improving the photoelectric conversion efficiency of the perovskite solar cell.

[0219] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0220] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A modified metal-organic framework material, characterized in that, include: The modified metal-organic framework material has a MIL-101 framework structure, comprising a metal ion and terephthalic acid and tetra(4-pyridyl)tetrathiofulvalene, both of which are coordinated to the metal ion.

2. The modified metal-organic framework material according to claim 1, characterized in that, One or more of the following conditions must be met: (1) The molar ratio of the terephthalic acid and the tetra(4-pyridyl)tetrathiofulvalene is (1~32):1; Optionally, the molar ratio of the terephthalic acid and the tetra(4-pyridyl)tetrathiofulvalene is (16~32):1; (2) The metal ions include one or both of chromium ions and iron ions; (3) The specific surface area of ​​the modified metal-organic framework material is 2300 m². 2 / g~4100m 2 / g; Optionally, the specific surface area of ​​the modified metal-organic framework material is 3900m². 2 / g~4100m 2 / g; (4) The pore volume of the modified metal-organic framework material is 1.6 cm³. 3 / g~1.9cm 3 / g; Optionally, the pore volume of the modified metal-organic framework material is 1.75 cm³. 3 / g~1.85cm 3 / g.

3. A method for preparing a modified metal-organic framework material, characterized in that, Includes the following steps: A modified metal-organic framework material with the MIL-101 framework structure was prepared by coordinating a metal salt, terephthalic acid, and tetra(4-pyridyl)tetrathiofulvalene to achieve coordination linkage between the metal ion, terephthalic acid, and tetra(4-pyridyl)tetrathiofulvalene.

4. The method for preparing the modified metal-organic framework material according to claim 3, characterized in that, The coordination reaction is carried out at a temperature of 175℃~195℃ for a reaction time of 18h~24h; and / or, In the coordination reaction step, an alkaline reagent and water were also added. The molar ratio of the metal salt, the alkaline reagent, the terephthalic acid, the tetra(4-pyridyl)tetrathiofulvalene and water was (0.5~2):(0.5~2):(1~32):1:(278~300).

5. The application of the modified metal-organic framework material according to any one of claims 1 to 2 or the modified metal-organic framework material prepared by the preparation method according to any one of claims 3 to 4 in the preparation of solar cells.

6. A solar cell, characterized in that, include: The perovskite layer, the dielectric layer, and the hole transport layer are disposed between the perovskite layer and the hole transport layer. The material of the dielectric layer includes the modified metal-organic framework material according to any one of claims 1 to 2 or the modified metal-organic framework material prepared by the preparation method according to any one of claims 3 to 4.

7. The solar cell according to claim 6, characterized in that, The solar cell satisfies one or more of the following conditions: (1) The thickness of the dielectric layer is 15nm~35nm; (2) The thickness of the hole transport layer is 15nm~20nm; (3) The material of the hole transport layer includes NiO. x and one or two of Cu2O; (4) The thickness of the perovskite layer is 1000 nm to 1200 nm; (5) The material of the perovskite layer includes one or more of MAPbI3, MAPbCl3 and MAPbBr3; (6) The solar cell further includes a transparent conductive substrate, an electron transport layer, a positive electrode and a negative electrode. The hole transport layer, the dielectric layer, the perovskite layer and the electron transport layer are sequentially stacked on the surface of the transparent conductive substrate. The positive electrode forms an ohmic contact with the transparent conductive substrate and the negative electrode forms an ohmic contact with the electron transport layer. Optionally, the material of the electron transport layer includes one or both of TiO2 and SnO2; Optionally, the thickness of the electron transport layer is 20 nm to 40 nm; Optionally, the thickness of the positive electrode and the negative electrode are each independently 200nm~300nm.

8. A method for fabricating a solar cell, characterized in that, Includes the following steps: A dielectric layer is formed between the perovskite layer and the hole transport layer to fabricate a solar cell; The material of the dielectric layer includes the modified metal-organic framework material according to any one of claims 1 to 2 or the modified metal-organic framework material prepared by the preparation method according to any one of claims 3 to 4.

9. The method for preparing a solar cell according to claim 8, characterized in that, The preparation steps of the dielectric layer include: applying a solution containing the modified metal-organic framework material to the surface of the hole transport layer, and annealing it at 100℃~150℃ for 8min~20min.

10. A photovoltaic module, characterized in that, The solar cell includes a packaging structure and the solar cell according to any one of claims 6 to 7, or includes a solar cell prepared by the preparation method according to any one of claims 8 to 9, wherein the solar cell is packaged by the packaging structure.

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