Perovskite film and preparation method thereof, perovskite solar cell

Abstract

This application relates to the field of solar cell technology, and more particularly to a perovskite film, its preparation method, and a perovskite solar cell. The method for preparing the perovskite film provided in this application includes: preparing a mixed solution containing a perovskite precursor, additives, and an initiator; wherein the additives include polymerizable acryloyl molecules containing positively charged and negatively charged groups, and the positively charged groups include N... + The negatively charged groups include at least one selected from phosphoryl, phosphonic, sulfonic, carboxyl, and mercapto groups. The mixed solution is treated to form a film, followed by a thermal polymerization reaction to obtain a perovskite film. The perovskite film prepared in this application, when used in solar cells, exhibits not only excellent energy conversion efficiency but also high reliability.

Description

Technical Field

[0001] This application belongs to the field of solar cell technology, and particularly relates to a perovskite film and its preparation method, and a perovskite solar cell. Background Technology

[0002] Perovskite is a class of semiconductor materials with uniform size and high color purity. Its elemental composition has a crystal structure similar to that of the ore CaTiO3, making it a promising photovoltaic material. Perovskite materials exhibit strong light absorption capabilities and a wide absorption range, giving them significant advantages in the optoelectronic field. For example, perovskite solar cells (PSCs) using perovskite as the light-absorbing layer are developing rapidly, attracting widespread attention from the industry due to their excellent carrier mobility, high absorption coefficient, and low-cost solution processing.

[0003] However, in the current perovskite crystallization film preparation process, there are generally defect sites in the grains, and the long-term reliability of perovskite films is low, which affects the device performance. Summary of the Invention

[0004] The purpose of this application is to provide a perovskite film and its preparation method, as well as a perovskite solar cell, in order to solve the technical problem of how to improve the performance of perovskite films.

[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0006] In a first aspect, this application provides a method for preparing a perovskite film, comprising: Prepare a mixed solution containing a perovskite precursor, additives, and an initiator; wherein the additives include polymerizable acryloyl molecules containing positively charged and negatively charged groups, and the positively charged groups include N... + The negatively charged group includes at least one selected from phosphoryl group, phosphonic acid group, sulfonic acid group, carboxyl group, and mercapto group; The mixed solution is subjected to a film-forming treatment followed by a thermal polymerization reaction to obtain a perovskite film.

[0007] In some embodiments, the positively charged group includes at least one of a primary amine group, a secondary amine group, and a quaternary amine group, and the negatively charged group includes a phosphoryl group.

[0008] In some embodiments, the additive includes 2-methacryloyloxyethyl phosphocholine; And / or, the initiator includes at least one of ammonium persulfate, dimethyl azobisisobutyrate, azobisisobutyronitrile, and azobisisobutyramidoline hydrochloride.

[0009] In some embodiments, the concentration of the additive in the mixed solution is 0.01 mmol / L to 10 mmol / L, and / or the concentration of the initiator is 0.001 mmol / L to 0.5 mmol / L.

[0010] In some embodiments, the molar ratio of the additive to the perovskite precursor is (0.05~0.11):100.

[0011] In some embodiments, the thermal polymerization reaction includes heat treatment at 90°C to 120°C.

[0012] Secondly, this application provides a perovskite film comprising a perovskite material and a polyacrylamide polymer bonded to the perovskite material, wherein the molecular chain of the polyacrylamide polymer includes positively charged groups and negatively charged groups, and the positively charged groups include N... + The negatively charged group includes at least one of phosphoryl group, phosphonic acid group, sulfonic acid group, carboxyl group, and mercapto group.

[0013] In some embodiments, the positively charged group includes at least one of a primary amine group, a secondary amine group, and a quaternary amine group, and the negatively charged group includes a phosphoryl group; And / or, the number average molecular weight of the polyacrylamide polymer is 9000 g / mol to 100000 g / mol; And / or, the molar ratio of the acrylamide structural units of the polyacrylamide polymer to the perovskite material is (0.05~0.11):100.

[0014] In some embodiments, the perovskite material in the perovskite film is an organic-inorganic hybrid perovskite, and the general chemical formula of the organic-inorganic hybrid perovskite is ABX3; wherein, A is a monovalent organic cation, B is a divalent metal cation, and X is a monovalent anion; And / or, the polyacrylamide polymers include poly(2-methacryloxyethyl phosphocholine).

[0015] Thirdly, this application provides a perovskite solar cell, including a perovskite film prepared by the preparation method provided in the first aspect of this application and / or a perovskite film provided in the second aspect of this application.

[0016] The method for preparing a perovskite film provided in the first aspect of this application involves a film-forming and thermal polymerization reaction of a mixed solution containing a perovskite precursor, additives, and an initiator to obtain a perovskite film. During this process, the additives in the mixed solution include polymerizable acryloyl molecules containing both positively and negatively charged groups. These additive molecules possess strong coordination capabilities, allowing them to interact with uncoordinated ions in the perovskite, thereby regulating the perovskite crystallization kinetics, guiding the formation of larger, uniform grains, and passivating defect sites in the grains, reducing non-radiative recombination losses. Simultaneously, these additives, as polymerizable monomers, can polymerize in situ within the perovskite film to form a high-molecular-weight elastomer network with amphoteric groups. This elastomer network can be distributed at the grain boundaries of the perovskite, combining chemical passivation and physical barrier functions. This not only effectively reduces the risk of ion migration at the grain boundaries but also releases the internal residual stress accumulated during the formation of the perovskite film. Therefore, the perovskite film prepared in this application not only has excellent energy conversion efficiency but also high reliability, making it well-suited for use in solar cells.

[0017] The perovskite film provided in the second aspect of this application includes a perovskite material and a specific polyacrylamide polymer bonded to the perovskite material. The positively and negatively charged groups on the polyacrylamide polymer molecular chain can regulate the crystallization kinetics of the perovskite, passivate defect sites in the grains, and reduce non-radiative recombination losses. Simultaneously, the polyacrylamide polymer can form an elastomer network distributed at the grain boundaries of the perovskite, possessing both chemical passivation and physical barrier functions. This not only effectively reduces the risk of ion migration at the grain boundaries but also releases the internal residual stress accumulated during the formation of the perovskite film. Therefore, the perovskite film of this application possesses both high energy conversion efficiency and high reliability.

[0018] The perovskite solar cell provided in the third aspect of this application includes the perovskite film prepared by the preparation method provided in the first aspect of this application and / or the perovskite film provided in the second aspect of this application. Based on the advantages of the perovskite film, the perovskite solar cell of this application not only has high energy conversion efficiency, but also good reliability.

[0019] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0021] Figure 1 This is a comparison diagram of the molecular structure before and after polymerization of a polymerizable acryloyl molecule added in the preparation method of the perovskite film provided in the embodiments of this application; Figure 2 These are microscopic comparison images of the perovskite films provided in the embodiments and comparative examples of this application; Figure 3 This is a microscopic distribution diagram of polyacrylamide polymers in the perovskite membrane provided in the embodiments of this application; Figure 4 These are XRD comparison images of the perovskite films provided in the embodiments and comparative examples of this application; Figure 5 These are comparison diagrams of crystal orientation tests of the perovskite films provided in the embodiments and comparative examples of this application; Figure 6 This is a comparison diagram of residual stress tests on perovskite films provided in the embodiments and comparative examples of this application; Figure 7 This is a comparison chart of the photovoltaic efficiency of perovskite solar cells provided in the embodiments and comparative examples of this application. Detailed Implementation

[0022] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0023] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0024] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items.

[0025] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0026] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0027] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a well-known unit of mass in the chemical industry, such as µg, mg, g, or kg.

[0028] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0029] Typically, during the fabrication of perovskite thin films, defects inevitably arise within the crystal structure, at grain boundaries, and at interfaces with other functional layers. These defects act as energy traps, capturing photogenerated carriers (electrons and holes) and causing them to be lost as heat before contributing to current. This process is called defect-mediated non-radiative recombination, which can easily lead to performance degradation in devices. Furthermore, during perovskite thin film fabrication and thermal annealing, residual stress easily accumulates within the perovskite film due to the mismatch in thermal expansion coefficients between materials and the crystallization process itself. This accumulated lattice stress accelerates the physical degradation of the perovskite film, severely impacting the long-term reliability of the device.

[0030] Based on this, in this embodiment, a polymerizable monomer additive containing zwitterionic compounds is added to the prepared perovskite precursor solution, and the polymer is formed in situ after the precursor solution is used to form a film. This allows the prepared perovskite film to not only reduce non-radiative recombination losses but also release the internal residual stress accumulated during film formation, exhibiting a distinct yet complementary dual-action mechanism. When such a perovskite film is applied to solar cells, it can enable perovskite solar cells to not only have excellent energy conversion efficiency but also excellent reliability. The specific technical solution is as follows.

[0031] This application provides a method for preparing a perovskite film. Specifically, the preparation method provided in this application includes: S01: Prepare a mixed solution containing a perovskite precursor, additives, and an initiator; wherein the additives include polymerizable acryloyl molecules containing both positively and negatively charged groups, and the positively charged groups include N... + The negatively charged groups include at least one of phosphoryl group, phosphonic acid group, sulfonic acid group, carboxyl group, and mercapto group; S02: After the mixed solution is treated to form a film, it undergoes a thermal polymerization reaction to obtain a perovskite film.

[0032] In the mixed solution prepared in this application embodiment for preparing perovskite films, an additive is added. The additive includes polymerizable acryloyl molecules containing positively charged and negatively charged groups, i.e. polymerizable monomer additives with zwitterionic compounds. The positively charged groups are positively charged atoms or atomic groups that have an electron-withdrawing inductive effect, and the negatively charged groups are negatively charged atoms or atomic groups that have an electron-donating inductive effect.

[0033] Specifically, the positively charged groups include N + That is, a nitrogen-containing positive ion; the negatively charged group includes a phosphoryl group (for example, in at least one of the following forms, -O-PO3H2 or -O-PO3). 2- , -O-PO2H-O- or -O-PO2 - -O-), phosphonic acid group (e.g., at least one of the following forms, -PO3H2 or -PO3). 2- ), sulfonic acid group (for example, in at least one of the following forms, -SO3H or -SO3), - ), carboxyl group (for example, in at least one of the following forms, -COOH or -COO) - ), thiol group (e.g., in at least one of the following forms, -SH or -S) - At least one of the following groups, i.e., these groups can carry a negative charge.

[0034] Among them, the phosphoryl group is a phosphorus-containing functional group, characterized by a phosphorus atom connected to an oxygen atom by a double bond and then to a hydroxyl group or other groups. The oxidation state of phosphorus is +5, and it is commonly found in compounds such as phosphate esters and phosphoramides. The phosphonate group refers to the phosphorus-containing group corresponding to phosphonates. Phosphonates are compounds in which one or two hydroxyl groups in a phosphoric acid molecule are replaced by alkyl or aryl groups. The core characteristic of the phosphonate group is that the phosphorus atom directly forms a stable carbon-phosphorus single bond (CP bond) with the carbon atom. The sulfonic acid group refers to the sulfonate group, also known as the sulfate acyl group, characterized by a sulfur atom connected to an oxygen atom by a double bond and then to a hydroxyl group. The carboxyl group is a functional group composed of a carbonyl group (C=O) and a hydroxyl group (-OH) directly linked. The mercapto group, also known as the hydrogen sulfide group or thiol group, is a functional group composed of a sulfur atom and a hydrogen atom linked together.

[0035] Among the aforementioned negatively charged groups, phosphoryl, phosphonic, sulfonic, carboxyl, and mercapto groups can be interpreted more broadly. In the additive raw materials, these groups can be neutral groups without charge, but after the additive is dissolved in a solvent, these groups can also form corresponding negatively charged groups. Because the negatively charged groups on the additive molecule are negatively charged after the additive is formulated into a solution, when the additive includes at least one of phosphoryl, phosphonic, sulfonic, carboxyl, and mercapto groups, at least one of these groups will carry a negative charge in the solution environment.

[0036] This polymerizable acrylamide molecule plays a role in regulating perovskite crystallization and passivating defects. In a mixed solution containing perovskite precursors, the polymerizable acrylamide molecule exists in the form of small molecules. Its molecular structure is rich in positively and negatively charged groups with strong coordination ability, enabling it to interact with uncoordinated ions in perovskite. For example, positively charged groups can interact with perovskite anions, and negatively charged groups can interact with perovskite cations. This interaction can, on the one hand, regulate the crystallization kinetics of perovskite, guiding the formation of larger, homogeneous grains; on the other hand, it can directly passivate defect sites in the crystal, thereby reducing non-radiative recombination losses.

[0037] Simultaneously, the polymerizable acrylamide molecules, after polymerization, form polyacrylamide polymers, which have the effect of reducing ion migration and releasing stress. After film formation treatment in the mixed solution, an initial film is formed. During the thermal polymerization reaction of this initial film, the polymerizable acrylamide monomers can undergo in-situ polymerization to form a polymer, thereby forming a high-molecular-weight zwitterionic elastomer network. This elastomer network is mainly distributed at the grain boundaries of the perovskite, and can act as an elastic scaffold with both chemical passivation and physical barrier functions. In this way, the elastomer network can not only effectively inhibit ion migration at the grain boundaries, but also, due to its elastic properties, act like a molecular shock absorber to release the internal residual stress accumulated during the formation of the perovskite film.

[0038] Therefore, in this embodiment, a mixed solution containing perovskite precursor, additives and initiator is subjected to film formation and thermal polymerization reaction. The perovskite film prepared in this way not only has good energy conversion efficiency, but also good reliability, and can be well used in solar cells.

[0039] In some embodiments, the additive can polymerize acryloyl molecules in which the positively charged groups include N. + (N-C) Specifically, the positively charged group includes at least one of primary amine groups, secondary amine groups, and quaternary amine groups. For example, after the additive is formulated into a solution, the primary amine groups, secondary amine groups, and quaternary amine groups can form N-containing... + Positively charged groups. Specifically, including N + The positively charged group can be -N + (CH3)3、-NH3 + Pyridinium ions, pyridinium ions, etc. The negatively charged groups include at least one of phosphoryl, phosphonic, sulfonic, carboxyl, and mercapto groups, which can coordinate well with perovskite cations. Further, the negatively charged groups include phosphoryl groups, such as -O-PO3H2 or -O-PO3. 2- , -O-PO2H-O- or -O-PO2 - -O-.

[0040] In some embodiments, the positively charged group is -N + (CH3)3, the negatively charged group is -O-PO2 - -O-. Optionally, the additive can polymerize acryloyl molecules including 2-methacryloyloxyethyl phosphocholine (MPC). 2-methacryloyloxyethyl phosphocholine (MPC), as an additive, is formulated into a mixed solution with the perovskite precursor, followed by film formation and thermal polymerization, such as... Figure 1As shown, 2-methacryloyloxyethyl phosphoric acid choline (MPC) contains a positively charged group -N. + (CH3)3, negatively charged group -O-PO2 - -O-, which can polymerize to form poly-2-methacryloyloxyethyl phosphocholine (PMPC), can not only reduce non-radiative recombination losses, but also release the internal residual stress accumulated during the formation of perovskite films.

[0041] In some embodiments, the concentration of the additive in the mixed solution can be from 0.01 mmol / L to 10 mmol / L; exemplaryly, the concentration of the additive can be any of the above values ​​or any combination thereof, such as 0.01 mmol / L, 0.05 mmol / L, 0.08 mmol / L, 0.1 mmol / L, 0.2 mmol / L, 0.4 mmol / L, 0.5 mmol / L, 0.8 mmol / L, 1 mmol / L, 1.5 mmol / L, 2 mmol / L, 2.5 mmol / L, 3 mmol / L, 3.5 mmol / L, 4 mmol / L, 4.5 mmol / L, 5 mmol / L, 5.5 mmol / L, 6 mmol / L, 6.5 mmol / L, 7 mmol / L, 7.5 mmol / L, 8 mmol / L, 8.5 mmol / L, 9 mmol / L, 10 mmol / L. The additive at the above concentrations can be uniformly dispersed in the mixed solution, allowing for sufficient reaction.

[0042] In some embodiments, the concentration of the initiator in the mixed solution is 0.001 mmol / L to 0.5 mmol / L. Exemplarily, the concentration of the initiator can be any of the above values ​​or any combination thereof, such as 0.001 mmol / L, 0.005 mmol / L, 0.008 mmol / L, 0.01 mmol / L, 0.02 mmol / L, 0.04 mmol / L, 0.05 mmol / L, 0.08 mmol / L, 0.1 mmol / L, 0.15 mmol / L, 0.2 mmol / L, 0.25 mmol / L, 0.3 mmol / L, 0.35 mmol / L, 0.4 mmol / L, 0.45 mmol / L, 0.5 mmol / L, etc. Initiator concentrations of the above can ensure sufficient polymerization of the additives in the mixed solution.

[0043] Specifically, an initiator, also known as a starting agent, is a chemical substance used to initiate the polymerization reaction of the aforementioned polymerizable acryloyl molecules. For example, it can be any one or more of the following: ammonium persulfate (APS), dimethyl 2,2'-azobisisobutyrate (MAIB), 2,2'-Azobis(2-methylpropionitrile) (AIBN), 2,2′-Azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (VA-044).

[0044] In some embodiments, the molar ratio of the additive to the perovskite precursor in the mixed solution is (0.05~0.11):100. Exemplarily, the molar ratio of the additive to the perovskite precursor can be any of the above values ​​or any combination thereof, such as 0.05:100, 0.06:100, 0.07:100, 0.08:100, 0.09:100, 0.10:100, 0.11:100, etc. The molar amount of the perovskite precursor refers to the molar amount that can generate the final perovskite.

[0045] In some embodiments, the perovskite precursor in the mixed solution may be a metal halide perovskite precursor, the metal halide perovskite material having the chemical formula ABX3; wherein, A is at least one of a monovalent organic cation and a monovalent inorganic cation, B is a divalent metal cation, and X is a monovalent anion, such as a halogen.

[0046] The perovskite precursor solution is obtained by dissolving a halide of a monovalent organic cation and a halide of a divalent metal cation in a solvent. Here, A is a monovalent organic cation, which may include CH3NH3. + (MA) + CH(NH2)2 + (FA) + ), ethylammonium (EA) + ), propylammonium (PA) + ), Butylammonium (BA) + A is at least one of the following, or A is a monovalent inorganic cation, which may include cesium ions (Cs). + Alternatively, A can include both monovalent inorganic cations and monovalent inorganic cations; B is a divalent metal cation, specifically including Pb. 2+ Sn 2+ At least one of them; X is a monovalent anion, specifically a halide ion, including Cl. - ,Br - and I- At least one of the following. Halides of monovalent organic cations and / or monovalent inorganic cations, or halides of divalent metal cations, are dissolved in a solvent to obtain a perovskite precursor solution.

[0047] In some embodiments, the perovskite material in the perovskite film obtained by the above method may have the chemical formula ABX3, which can be FA. 1-x MA x PbI3 (where 0≤x≤1), or MAPb(I 1-x Br x )3 (where 0≤x≤1), or FA 1-x MA x Sn 1- x Pb x I3 (where 0 ≤ x ≤ 1), or FA 1-x MA x Pb(I 1-x Br x )3 (where 0 ≤ x ≤ 1). Alternatively, it could be (BA)2(MA). x-1 Pb x I 3x+1 (where 1≤x).

[0048] In some embodiments, the preparation of the mixed solution includes: separately preparing a perovskite precursor solution and an additive solution, and then mixing them. Specifically, a perovskite precursor solution is obtained by dissolving a halide of a monovalent organic cation and / or a monovalent inorganic cation, or a halide of a divalent metal cation, in a solvent. An additive solution is prepared by dissolving polymerizable acryloyl molecules and an initiator in a solvent. The perovskite precursor solution and the additive solution are mixed to obtain a mixed solution containing the perovskite precursor, the additive, and the initiator. The solvent in the perovskite precursor solution can be at least one of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The solvent in the additive solution can be dimethyl sulfoxide (DMSO).

[0049] In some implementations, the film formation process of the mixed solution can be spin-coating. For example, the mixed solution is spin-coated at a speed of 2000–6000 rpm. To rapidly induce crystallization, an anti-solvent, such as chlorobenzene (CB), can be added dropwise before the end of the spin-coating process to induce rapid crystallization. Immediately after spin-coating, the sample is heat-treated, during which the additives undergo in-situ polymerization.

[0050] In some embodiments, the thermal polymerization reaction includes heat treatment at 90°C to 120°C. Exemplarily, the thermal polymerization reaction temperature can be any of the above values ​​or any combination thereof, such as 90°C, 95°C, 100°C, 105°C, 110°C, 120°C, etc. Further, the thermal polymerization reaction time can be 20 to 40 minutes. After spin-coating the mixed solution into a film, the sample is immediately transferred to a hot plate for annealing at the above-mentioned temperature conditions, allowing the additive to undergo sufficient in-situ polymerization.

[0051] In some embodiments, the additive can polymerize acrylamide molecules in situ to form polyacrylamide polymers with a number average molecular weight of 9000 g / mol to 100000 g / mol, thereby forming a good elastomer network that has both chemical passivation and physical barrier functions. This not only effectively reduces the risk of ion migration at grain boundaries, but also releases the internal residual stress accumulated during the formation of the perovskite film.

[0052] Secondly, embodiments of this application provide a perovskite membrane. Specifically, the perovskite membrane of this application includes a perovskite material and a polyacrylamide polymer bonded to the perovskite material. The molecular chain of the polyacrylamide polymer includes positively charged groups and negatively charged groups, and the positively charged groups include N... + The negatively charged groups include phosphoryl groups (e.g., in at least one of the following forms, -O-PO3H2 or -O-PO3). 2- , -O-PO2H-O- or -O-PO2 - -O-), phosphonic acid group (e.g., at least one of the following forms, -PO3H2 or -PO3). 2- ), sulfonic acid group (for example, in at least one of the following forms, -SO3H or -SO3), - ), carboxyl group (for example, in at least one of the following forms, -COOH or -COO) - ), thiol group (e.g., in at least one of the following forms, -SH or -S) - At least one of the following.

[0053] The positively and negatively charged groups on the polyacrylamide polymer molecular chains in the perovskite film provided in this application can regulate the crystallization kinetics of perovskite, passivate defect sites in the grains, and reduce non-radiative recombination losses. Simultaneously, the polyacrylamide polymer can form an elastomer network distributed at the grain boundaries of the perovskite, combining chemical passivation and physical barrier functions. This not only effectively reduces the risk of ion migration at the grain boundaries but also releases the internal residual stress accumulated during the formation of the perovskite film. Therefore, the perovskite film of this application embodiment possesses both high energy conversion efficiency and high reliability.

[0054] In some embodiments, the perovskite film described above in this application is prepared by the perovskite film preparation method provided in the first aspect of this application. Specifically, a perovskite film is obtained by performing a film-forming and thermal polymerization reaction on a mixed solution containing a perovskite precursor, additives, and an initiator. Polymerizable acryloyl molecules containing positively and negatively charged groups can be polymerized in situ to form polyacrylamide polymers. The positively and negatively charged groups on the polyacrylamide polymer molecular chains have strong coordination capabilities and can interact with uncoordinated ions in the perovskite, thereby regulating the crystallization kinetics of the perovskite, guiding the formation of larger uniform grains, and passivating defect sites in the grains, reducing non-radiative recombination losses. At the same time, the polyacrylamide polymers polymerized in situ in the perovskite film can form a high molecular weight elastomer network with amphoteric groups. This elastomer network can be distributed at the grain boundaries of the perovskite, combining chemical passivation and physical barrier functions. It can not only effectively reduce the risk of ion migration at the grain boundaries but also release the internal residual stress accumulated during the formation of the perovskite film.

[0055] In some embodiments, the positively charged groups on the polyacrylamide polymer molecular chain include at least one of primary amine groups, secondary amine groups, and quaternary amine groups, for example, -N. + (CH3)3、-NH3 + Pyridinium ions, pyridinium ions, etc. The negatively charged groups include at least one of phosphoryl, phosphonic, sulfonic, carboxyl, and mercapto groups, which can coordinate well with perovskite cations. Further, the negatively charged groups include phosphoryl groups, such as -O-PO3H2 or -O-PO3. 2- , -O-PO2H-O- or -O-PO2 - -O-.

[0056] In some embodiments, the polyacrylamide polymer includes poly(2-methacryloyloxyethyl phosphocholine), which is polymerized from 2-methacryloyloxyethyl phosphocholine additives, and contains a positively charged group -N. + (CH3)3, negatively charged group -O-PO2 - -O-.

[0057] In some embodiments, the number average molecular weight of the polyacrylamide polymer is 9000 g / mol to 100000 g / mol; exemplaryly, the number average molecular weight of the polyacrylamide polymer can be any of the above values ​​or any combination thereof, such as 9000 g / mol, 10000 g / mol, 20000 g / mol, 30000 g / mol, 40000 g / mol, 50000 g / mol, 60000 g / mol, 70000 g / mol, 80000 g / mol, 90000 g / mol, 100000 g / mol, etc.

[0058] In some embodiments, the molar ratio of the acrylamide structural units of the polyacrylamide polymer to the perovskite material is (0.05~0.11):100. Exemplarily, the molar ratio of the acrylamide structural units of the polyacrylamide polymer to the perovskite material can be any of the above values ​​or any combination thereof, such as 0.05:100, 0.06:100, 0.07:100, 0.08:100, 0.09:100, 0.10:100, 0.11:100, etc. The acrylamide structural unit corresponds to the structure formed after the polymerizable acrylamide molecules in the raw material have polymerized.

[0059] In some embodiments, the perovskite film of this application comprises a perovskite material and a polyacrylamide polymer, and may further include an initiator. The proportion and type of initiator depend on the addition of the prepared mixed solution during the perovskite film preparation steps.

[0060] In some embodiments, the perovskite material in the perovskite film comprises a metal halide perovskite with the general chemical formula ABX3; wherein A is a monovalent organic cation, B is a divalent metal cation, and X is a monovalent anion. For example, A being a monovalent organic cation may include CH3NH3. + (MA) + CH(NH2)2 + (FA) + ), ethylammonium (EA) + ), propylammonium (PA) + ), Butylammonium (BA) + A is at least one of the following, or A is a monovalent inorganic cation, which may include cesium ions (Cs). + Alternatively, A can include both monovalent inorganic cations and monovalent inorganic cations; B is a divalent metal cation, specifically including Pb. 2+ Sn 2+ At least one of them; X is a monovalent anion, specifically a halide ion, including Cl. - ,Br - and I - At least one of the following. In some embodiments, the perovskite material with the chemical formula ABX3 may be FA. 1-x MA x PbI3 (where 0≤x≤1), or MAPb(I 1-x Br x )3 (where 0≤x≤1), or FA 1-x MA x Sn 1-x Pb x I3 (where 0 ≤ x ≤ 1), or FA 1-x MA xPb(I 1-x Br x )3 (where 0 ≤ x ≤ 1). Alternatively, it could be (BA)2(MA). x-1 Pb x I 3x+1 (where 1≤x).

[0061] Thirdly, embodiments of this application provide a perovskite solar cell. Specifically, the perovskite solar cell includes a perovskite film prepared by the preparation method provided in the first aspect of this application and / or a perovskite film provided in the second aspect of this application.

[0062] The perovskite solar cell of this application includes the perovskite film of this application. Based on the advantages of the perovskite film, the perovskite solar cell of this application not only has high energy conversion efficiency, but also good reliability.

[0063] Specifically, in a perovskite solar cell module, wherever the perovskite film is present, whether it is the dead area, active area, or mark area, it can exhibit both high conversion efficiency and reliability.

[0064] Specifically, the perovskite solar cell of this application embodiment includes a first electrode, a second electrode, and a perovskite layer located between the first electrode and the second electrode. This perovskite layer includes a perovskite film prepared by the preparation method provided in the first aspect of this application embodiment and / or a perovskite film provided in the second aspect of this application embodiment. Further, a hole transport layer is disposed between the perovskite layer and the first electrode, and an electron transport layer can also be disposed between the perovskite layer and the second electrode. Alternatively, an electron transport layer is disposed between the perovskite layer and the first electrode, and a hole transport layer can also be disposed between the perovskite layer and the second electrode. The specific perovskite solar cell model can be selected according to actual needs.

[0065] In some embodiments, the electron transport layer can be a carbon material, a metal oxide, or a doped metal oxide, etc. For example, the metal oxide includes at least one of TiO2, NiOx, SnO2, ZrO2, and ZnO. The electron transport layer can be a single metal oxide layer or two stacked metal oxide layers.

[0066] In some embodiments, a hole transport layer is provided to further improve the hole transport performance of perovskite solar cells. Specifically, the material of the hole transport layer may include [4-(7H-dibenzocarbazole-7-yl)butyl]phosphate (4PADCB)2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly-3-hexylthiophene (P3HT), triphenylamine with a triphenylene core (H101), 3,4-ethylenedioxythiophene-methoxytriphenylamine (EDOT-OMeTPA), N-(4-aniline)carbazole-spirodifluorene (CzPAF-SBF), poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), or modified materials of the above materials, etc.

[0067] In some embodiments, the first electrode may be a transparent conductive substrate, including but not limited to the following materials: fluorine-doped tin oxide (FTO), indium-doped tin oxide (ITO), aluminum-doped zinc oxide (AZO), boron-doped zinc oxide (BZO), indium-doped zinc oxide (IZO), etc. The second electrode may be a metal top electrode, such as gold, silver, copper, etc., or one or more of conductive oxide electrodes.

[0068] In some embodiments, the method for fabricating the perovskite solar cell includes: 1) fabricating an electron transport layer on a first electrode; 2) fabricating a perovskite layer on the electron transport layer, i.e., fabricating a perovskite film using the fabrication method provided in the first aspect of this application; and 3) fabricating a second electrode on the perovskite layer. This method allows the fabrication of a perovskite film on the electron transport layer. Alternatively, a hole transport layer can be fabricated first on the perovskite layer, and then the second electrode can be fabricated on the hole transport layer.

[0069] In some embodiments, the method for fabricating the perovskite solar cell includes: 1) fabricating a hole transport layer on a first electrode; 2) fabricating a perovskite layer on the hole transport layer, i.e., fabricating a perovskite film using the fabrication method provided in the first aspect of this application; and 3) fabricating a second electrode on the perovskite layer. This method allows the fabrication of a perovskite film on the hole transport layer. Alternatively, an electron transport layer can be fabricated first on the perovskite layer, and then the second electrode can be fabricated on the electron transport layer.

[0070] The following description is based on specific embodiments.

[0071] Example 1 A perovskite solar cell and its fabrication method are disclosed. The perovskite solar cell structure sequentially comprises: a first electrode (material: ITO substrate), a hole transport layer (materials including: 4PADCB and Al2O3), and a perovskite layer (containing perovskite material is FA). 0.95 Cs 0.05 PbI3), electron transport layer (material: C) 60 And SnO2), second electrode (material: metallic silver).

[0072] The above-mentioned methods for fabricating perovskite solar cells include: Step 1: Substrate pretreatment. The pre-patterned ITO substrate is ultrasonically cleaned sequentially with deionized water, acetone, and ethanol. Finally, it is dried with nitrogen and treated with ultraviolet ozone to enhance the surface hydrophilicity.

[0073] Step 2: Hole Transport Layer (HTL) Preparation. A 0.5 mg / ml 4PADCB solution (ethanol solvent) was spin-coated onto the treated ITO substrate and annealed at 100°C for 10 minutes to form a self-assembled monolayer. Next, a diluted Al₂O₃ solution was spin-coated and annealed at 100°C for 5 minutes as a modification layer. The final hole transport layer was obtained.

[0074] Step 3: Preparation of the perovskite layer.

[0075] Cesium iodide (CsI), formamidine iodide (FAI), and lead iodide (PbI2) were classified as perovskite material FA. 0.95 Cs 0.05 PbI3 was dissolved in a stoichiometric mixture of DMF and DMSO (volume ratio DMF:DMSO = 4:1) to prepare FA with a concentration of 1.5 M. 0.95 Cs 0.05 The PbI3 perovskite precursor solution was then further supplemented with 3 mol% PbI2 and 10 mol% methylammonium chloride (MACl) to obtain the final perovskite precursor solution.

[0076] An additive solution was prepared by dissolving 10 mg of 2-methacryloyloxyethyl phosphocholine (MPC) and 0.5 mg of the initiator ammonium persulfate (APS) in 1 ml of DMSO solvent.

[0077] Add 25 μL of the above additive solution to 500 μL of the above perovskite precursor solution and stir until homogeneous to obtain a mixed solution.

[0078] In a nitrogen glove box, 50 μL of the mixed solution was spin-coated at 4000 rpm for 50 seconds. Ten seconds before the end of the spin-coating process, 150 μL of chlorobenzene (CB) was added as an anti-solvent to induce rapid crystallization. After spin-coating, the sample was transferred to a hot plate at 100°C and annealed for 30 minutes, during which in-situ polymerization of MPC occurred. On the cooled perovskite film, a mixture of phenylethyl ammonium iodide (PEAI) and ethylenediamine dihydroiodide (EDAI2) in isopropanol was dynamically spin-coated to passivate surface defects, followed by annealing at 100°C for 5 minutes to obtain the perovskite film.

[0079] Step 4: Electron Transport Layer (ETL) Fabrication. A 20 nm C layer was deposited via thermal evaporation. 60 Then, an electron transport layer of 20 nm SnO2 is deposited at 100 °C using atomic layer deposition (ALD) technology.

[0080] Step 5: Top electrode fabrication. A 100nm layer of silver (Ag) is deposited as the top electrode under vacuum conditions via thermal evaporation to complete the device fabrication.

[0081] Comparative Example 1 A method for preparing a perovskite solar cell differs from the preparation steps in Example 1 in that the perovskite layer is prepared as follows: The perovskite precursor solution from Example 1 is spin-coated at 4000 rpm for 50 seconds. Ten seconds before the end of the spin-coating process, 150 μL of chlorobenzene (CB) is added as an antisolvent to induce rapid crystallization. After spin-coating, the sample is transferred to a hot plate at 100°C and annealed for 30 minutes, during which in-situ polymerization of MPC occurs. On the cooled perovskite film, a mixed solution of phenylethyl ammonium iodide (PEAI) and ethylenediamine dihydroiodide (EDAI2) in isopropanol is dynamically spin-coated to passivate surface defects, followed by annealing at 100°C for 5 minutes to obtain the perovskite film.

[0082] That is, the perovskite precursor solution without the addition of 2-methacryloyloxyethyl phosphocholine (MPC) was used to form the film, and everything else was the same as in Example 1.

[0083] Performance testing (1) Microscopic detection of perovskite films Figure 2 These are scanning electron microscope (SEM) images of the perovskite films provided in Example 1 and Comparative Example 1 of this application. In the image, a is a sample image of the perovskite film of Comparative Example 1 (represented by control), and b is a sample image of the perovskite film of Example 1 (represented by P-MPC). This shows that Example 1 can guide the formation of larger, homogeneous grains. Figure 3It is the perovskite film of Example 1, wherein a polymer formed of 2-methacryloyloxyethyl phosphocholine is distributed in the perovskite.

[0084] (2) XRD pattern X-ray diffraction (XRD) detection, such as Figure 4 As shown, the results indicate that the perovskite film sample (P-MPC) of Example 1 exhibits stronger diffraction peaks and narrower full width at half maximum (FWHM), suggesting higher crystallinity. Scanning electron microscopy (SEM) images further confirm that the P-MPC film has larger and more uniform grain size, and no unreacted PbI2 residues were observed on the surface, indicating a more complete phase transition. The perovskite film sample (Control) of Comparative Example 1 has relatively poor crystallinity.

[0085] (3) Crystal orientation and residual stress test X-ray diffraction (GIXRD, Rigaku SmartLab) was used to analyze the residual tensile thermal stress of the perovskite film. Grazing incidence wide-angle X-ray scattering (GIWAXS) spectra were obtained at the BL14B1 beamline of the Shanghai Synchrotron Radiation Facility (SSRF). The perovskite film samples of Example 1 and Comparative Example 1 were directly scanned by X-ray diffraction at different incident angles.

[0086] By using different ψ angles for X-ray incident detection, crystal arrangement can be detected from different directions, thereby determining whether the grains have a better preferred orientation.

[0087] The ψ angle is the tilt angle between the incident X-ray direction and the normal (vertical) direction of the thin film when scanning the sample. When ψ = 0° or 10°: the X-ray is almost directly facing the thin film surface, thus biased to measure "out-of-plane orientation". As ψ increases (e.g., 20°, 30°, 40°, 50°): the X-ray becomes more oblique, thus becoming more sensitive to "in-plane orientation" crystal signals.

[0088] The results are as follows Figure 5 As shown, in the perovskite film sample (P-MPC) of Example 1, it can be found that the lattice structure of the film does not change significantly due to stress, indicating that the doping of elastic polymer does improve the stress resistance of the perovskite film. In contrast, the perovskite film sample (Control) of Comparative Example 1 shows a very obvious change in the lattice state, indicating that the original perovskite film has a very poor resistance to stress and the crystal structure has changed significantly.

[0089] Additionally from Figure 6As shown, the perovskite film sample (P-MPC) of Example 1 has lower residual stress than the perovskite film sample (Control) of Comparative Example 1.

[0090] (4) Detection of perovskite solar cells The perovskite solar cells prepared in the above embodiments and comparative examples were connected to the testing fixture of a solar simulator and a cell performance testing instrument, and IV curve scanning was performed, including forward sweep (FS) and reverse sweep (RS). The power conversion efficiency (PCE), short-circuit current (Jsc), open-circuit voltage (Voc), and fill factor (FF) were then calculated, and the results are shown in Table 1 and... Figure 7 As shown.

[0091] Table 1

[0092] In summary, the embodiments of this application add a unique polymerizable acryloyl molecule additive to the perovskite precursor for film formation and thermal polymerization reaction. This can reduce non-radiative recombination loss and release the internal residual stress accumulated during the formation of the perovskite film. As a result, the perovskite film obtained not only has good energy conversion efficiency but also good reliability, and can be well used in solar cells.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing a perovskite film, characterized in that, include: Prepare a mixed solution containing a perovskite precursor, additives, and an initiator; wherein the additives include polymerizable acryloyl molecules containing positively charged and negatively charged groups, and the positively charged groups include N... + The negatively charged group includes at least one selected from phosphoryl group, phosphonic acid group, sulfonic acid group, carboxyl group, and mercapto group; The mixed solution is subjected to a film-forming treatment followed by a thermal polymerization reaction to obtain a perovskite film.

2. The preparation method according to claim 1, characterized in that, The positively charged group includes at least one of a primary amine group, a secondary amine group, and a quaternary amine group, and the negatively charged group includes a phosphoryl group.

3. The preparation method according to claim 2, characterized in that, The additive includes 2-methacryloyloxyethyl phosphocholine; And / or, the initiator includes at least one of ammonium persulfate, dimethyl azobisisobutyrate, azobisisobutyronitrile, and azobisisobutyramidoline hydrochloride.

4. The preparation method according to any one of claims 1-3, characterized in that, In the mixed solution: the concentration of the additive is 0.01 mmol / L to 10 mmol / L, and / or the concentration of the initiator is 0.001 mmol / L to 0.5 mmol / L.

5. The preparation method according to any one of claims 1-3, characterized in that, The molar ratio of the additive to the perovskite precursor is (0.05~0.11):

100.

6. The preparation method according to any one of claims 1-3, characterized in that, The thermal polymerization reaction includes heat treatment at 90℃~120℃.

7. A perovskite film, characterized in that, This includes perovskite materials and polyacrylamide polymers bonded to the perovskite materials. The molecular chains of the polyacrylamide polymers include both positively charged and negatively charged groups, with the positively charged groups including N... + The negatively charged group includes at least one of phosphoryl group, phosphonic acid group, sulfonic acid group, carboxyl group, and mercapto group.

8. The perovskite film as described in claim 7, characterized in that, The positively charged group includes at least one of a primary amine group, a secondary amine group, and a quaternary amine group, and the negatively charged group includes a phosphoryl group; And / or, the number average molecular weight of the polyacrylamide polymer is 9000 g / mol to 100000 g / mol; And / or, the molar ratio of the acrylamide structural units of the polyacrylamide polymer to the perovskite material is (0.05~0.11):

100.

9. The perovskite film according to any one of claims 7-8, characterized in that, The perovskite material in the perovskite film includes metal halide perovskite, the general chemical formula of which is ABX3; wherein, A is at least one of monovalent organic cation and monovalent inorganic cation, B is a divalent metal cation, and X is a monovalent anion; And / or, the polyacrylamide polymers include poly(2-methacryloxyethyl phosphocholine).

10. A perovskite solar cell, characterized in that, This includes the perovskite film prepared by the preparation method according to any one of claims 1-6 and / or the perovskite film according to any one of claims 7-9.

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