Perovskite material and preparation method therefor, perovskite device, and photovoltaic module
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-11-26
- Publication Date
- 2026-08-13
Smart Images
Figure CN2025137899_13082026_PF_FP_ABST
Abstract
Description
Perovskite materials and their preparation methods, perovskite devices, photovoltaic modules
[0001] This application claims priority to Chinese Patent Application No. 202510134212.7, filed with the Chinese Patent Office on February 6, 2025, the entire contents of which are incorporated herein by reference. Technical Field
[0002] This application relates to the field of optoelectronic materials technology, and in particular to a perovskite material and its preparation method, perovskite devices, and photovoltaic modules. Background Technology
[0003] Perovskite materials have become a research hotspot in the photovoltaic industry and other fields due to their unique photoelectric properties. However, in practical applications, it is difficult to simultaneously achieve both stability and uniformity of perovskite composition. For example, although some techniques can improve the stability of the perovskite bulk phase to a certain extent, they can still easily lead to phase segregation in the perovskite, resulting in poor homogeneity of the entire perovskite system. Summary of the Invention
[0004] To address the aforementioned technical problems, this application discloses a perovskite material and its preparation method, a perovskite device, and a photovoltaic module. By optimizing the perovskite material, its structural stability and material uniformity when used as a light-absorbing material are improved.
[0005] In the first aspect, this application provides a perovskite material having a three-dimensional structure, wherein the chemical formula of the perovskite material is ABX3, wherein A is an A-position cation, B is a B-position cation, and X is an X-position anion;
[0006] The A-site cation includes at least five different types of cations, one of which is a formamidinium cation. The other types of A-site cations include first-type A-site cations with ionic radii smaller than that of the formamidinium cation and second-type A-site cations with ionic radii larger than that of the formamidinium cation. Among the A-site cations, the atomic percentage of the first-type A-site cations is greater than that of the second-type A-site cations. Among the A-site cations, the atomic percentage of the formamidinium cation is 50% to 90%.
[0007] Furthermore, the first type of A-site cation includes at least two types.
[0008] Furthermore, the band gap of the perovskite material is 1.65 eV to 1.80 eV.
[0009] Furthermore, the atomic percentage of the second type of A-site cation in the A-site cation is less than or equal to 10%.
[0010] Furthermore, the X-position anion comprises at least three different types of halide anions and / or pseudohalogen anions, wherein one of the X-position anions is I. - Other types of X-position anions include those with ionic radii smaller than that of the I-position anion. - The first type of X-position anion, with an ionic radius greater than that of the I - The second type of X-position anion, wherein the first type of X-position anion includes at least one type, and the second type of X-position anion includes at least one type; wherein the atomic percentage of the first type of X-position anion is greater than the atomic percentage of the second type of X-position anion.
[0011] Furthermore, the first type of A-site cation includes MA. + Cs + K + Ca 2+ Zn 2+ Na + or Rb + At least two of them; and / or,
[0012] The second type of A-site cation includes DMA. + BA + PA + AA + BMIM + EA + or EDA 2+ At least one of them; and / or,
[0013] The B-site cation includes Pb. 2+ Ga 2+ and Sn 2+ At least one of them; and / or,
[0014] The X-position anion includes I - Ionic radius is smaller than that of I - The first type of X-position anion, with an ionic radius greater than that of the I - The second type of X-position anion, wherein the first type of X-position anion includes F - ,Br - Cl - At least one of them, wherein the second type of X-position anion includes SCN. - OCN - BF4 - TFSI - CF3 - CF3CO2 - COO - or SO3H -At least one of the following, in the X-position anion, the I - The atomic percentage is greater than or equal to 50%.
[0015] Furthermore, the chemical formula of the perovskite material is (FA). a1 DMA a2 MA a3 PA a4 Cs a5 Rb a6 PbI3, a1:a2:a3:a4:a5:a6=(50~90):(0.5~5):(3~22):(1~6):(1~16):(0.5~10); or,
[0016] The chemical formula of the perovskite material is (FA). a1 DMA a2 MA a3 PA a4 Cs a5 Rb a6 )Pb(I b1 Cl b2 Br b3 ), a1:a2:a3:a4:a5:a6=(50~90):(0.5~5):(3~22):(1~6):(1~16):(0.5~10), b1:b2:b3=(70~95):(0.5~8):(3~25); or,
[0017] The chemical formula of the perovskite material is (FA). a1 DMA a2 MA a3 PA a4 Cs a5 Rb a6 )Pb(I b1 Cl b2 Br b3 OCN b4 SCN b5 ), a1:a2:a3:a4:a5:a6=(50~90):(0.5~5):(3~22):(1~6):(1~16):(0. 5~10), b1:b2:b3:b4:b5=(70~90):(0.5~6):(2~20):(0.5~8):(0.5~8).
[0018] Secondly, this application provides a method for preparing a perovskite material as described in the first aspect, the method comprising the following steps:
[0019] A cationic solution is coated onto the framework layer, and then annealed to obtain the perovskite material.
[0020] The framework layer includes at least the B-site cation and the X-site anion, and the cation solution includes some or all of the A-site cation.
[0021] Furthermore, the surface of the skeleton layer has a velvety structure; and / or,
[0022] The thickness of the perovskite film is 500 nm to 2000 nm; and / or,
[0023] The A-site cation is divided into alkali metal cation and organic cation. Before the step of coating the cation solution on the framework layer, the method for preparing the perovskite material further includes the following steps:
[0024] Preparation of the framework layer: The material source containing the alkali metal cation, the material source containing the B-site cation, and the material source containing the X-site anion are co-deposited by vapor deposition to obtain the framework layer;
[0025] Preparation of the cation solution: Dissolve the organic cation in an organic solvent.
[0026] Further, in the step of preparing the framework layer, PbI2, CsBr, and RbBr are co-deposited at a deposition rate ratio of (8-12):(0.5-2.2):(0.1-1.2) to obtain a lead iodide framework layer containing alkali metal inorganic salts, the thickness of which is 300 nm-750 nm; and / or,
[0027] In the step of preparing the cationic solution, FAI, DMAI, MAI, MACl, and PACl are dissolved in isopropanol in an atomic percentage ratio of (70–90):(3–12):(8–12):(8–22):(3–12) to obtain the cationic solution; and / or,
[0028] In the step of preparing the cationic solution, the organic solvent includes at least one selected from ethanol and isopropanol; and / or,
[0029] In the step of coating the cation solution onto the framework layer, according to the FA in the A-site cation... + :DMA + :MA + :PA + :Cs + :Rb + The atomic percentages are (70~90):(3~6):(6~18):(2~6):(4~6):(2~5) for coating.
[0030] Thirdly, this application provides a perovskite device comprising the perovskite material as described in the first aspect, or the perovskite device comprising the perovskite material prepared by the preparation method described in the second aspect.
[0031] Furthermore, the perovskite device includes at least one of a perovskite solar cell, a perovskite light-emitting diode, or a perovskite laser.
[0032] Furthermore, the perovskite device is a perovskite tandem solar cell, which includes: a bottom cell with a planar or textured surface; an electron-hole recombination layer, a first transport layer, a perovskite light-absorbing layer, a second transport layer, and a transparent conductive layer sequentially disposed on the surface of the bottom cell; a first electrode electrically in contact with the transparent conductive layer; and a second electrode electrically in contact with the bottom cell; wherein, one of the first transport layer and the second transport layer is an electron transport layer and the other is a hole transport layer; one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode; and the perovskite light-absorbing layer comprises the perovskite material.
[0033] Alternatively, the perovskite device is a perovskite single-junction solar cell, which includes: a transparent conductive substrate with a planar or textured surface; a first transport layer, a perovskite light-absorbing layer, and a second transport layer sequentially disposed on the transparent conductive substrate; a first electrode electrically in contact with the second transport layer; and a second electrode electrically in contact with the transparent conductive substrate; wherein, one of the first transport layer and the second transport layer is an electron transport layer and the other is a hole transport layer; one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode; and the perovskite light-absorbing layer comprises the perovskite material.
[0034] Further, the perovskite device is the perovskite tandem solar cell, and the bottom cell includes at least one of crystalline silicon bottom cells, copper indium gallium selenide bottom cells, perovskite narrow bandgap bottom cells, or organic bottom cells; and / or,
[0035] The electron-hole recombination layer is made of at least one of IZO and ITO; and / or,
[0036] The thickness of the electron-hole recombination layer is 2nm to 30nm;
[0037] The hole transport layer is made of nickel oxide; and / or,
[0038] The thickness of the hole transport layer is 5 nm to 30 nm; and / or,
[0039] The thickness of the perovskite light-absorbing layer is 500 nm to 2000 nm; and / or,
[0040] The material of the electron transport layer includes C. 60 ; and / or,
[0041] The thickness of the electron transport layer is 5 nm to 30 nm; and / or,
[0042] The material of the transparent conductive layer includes at least one of ITO, IZO, or IWO; and / or,
[0043] The thickness of the transparent conductive layer is 30nm to 150nm; and / or,
[0044] The electrode is made of at least one of gold, silver, copper, or aluminum; and / or,
[0045] The thickness of the electrode is 50 nm to 400 nm.
[0046] Furthermore, the perovskite device is the perovskite tandem solar cell, and the perovskite tandem solar cell further includes:
[0047] A hole-modifying layer is disposed between the hole transport layer and the perovskite light-absorbing layer. The material of the hole-modifying layer is a single-molecule self-assembled material, including at least one of 2PACz, 4PACz, or MeO-2PACz; and / or...
[0048] A passivation layer is disposed between the perovskite light-absorbing layer and the second transmission layer. The material of the passivation layer includes LiF or a two-dimensional perovskite material, and the thickness of the passivation layer is 0.5 nm to 5 nm; and / or,
[0049] A buffer layer is disposed between the second transport layer and the transparent conductive layer, the thickness of the buffer layer being 5 nm to 30 nm; and / or,
[0050] An antireflection layer is disposed on the side of the transparent conductive layer opposite to the second transmission layer, and the thickness of the antireflection layer is 80nm to 150nm.
[0051] Fourthly, this application provides a photovoltaic module, the photovoltaic module including a solar cell, the solar cell including a perovskite light-absorbing layer, the perovskite light-absorbing layer including the perovskite material as described in the first aspect, or the perovskite light-absorbing layer including the perovskite material prepared by the preparation method described in the second aspect.
[0052] Compared with the prior art, this application has at least the following beneficial effects:
[0053] The perovskite material disclosed in this application, through synergistic control of the cation type, cation radius, and cation ratio of the three-dimensional perovskite material, ensures that while increasing the entropy value of the perovskite material, it effectively improves the phase segregation problem of the perovskite material. This not only enhances the effect of the increased entropy value on the bulk stability of the perovskite material, but also improves the uniformity of the three-dimensional perovskite material by reducing phase segregation. From the aspects of bulk stability and uniformity, the comprehensive performance of the perovskite material is effectively improved, which in turn helps to improve the service life and photoelectric conversion performance of devices using perovskite materials. Attached Figure Description
[0054] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments 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.
[0055] Figure 1 is a schematic diagram of the structure of the perovskite tandem solar cell in the embodiment of this application.
[0056] Explanation of reference numerals in the attached figures: 1. Bottom cell; 2. Electron-hole recombination layer; 31. First transport layer; 32. Second transport layer; 4. Perovskite light-absorbing layer; 5. Transparent conductive layer; 61. First electrode; 62. Second electrode; 7. Hole modification layer; 8. Passivation layer; 9. Buffer layer; 10. Antireflection layer. Detailed Implementation
[0057] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0058] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.
[0059] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.
[0060] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.
[0061] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (the specific types and structures may be the same or different), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.
[0062] Perovskite materials suffer from poor bulk stability and are prone to phase segregation, limiting their development in industrial applications. Taking three-dimensional perovskite materials as the light-absorbing layer of perovskite solar cells as an example, their poor bulk stability easily leads to insufficient long-term stability of the perovskite cells, affecting their lifespan. Some approaches use additives or passivation layers to improve the bulk stability of perovskite materials, but since these do not fundamentally change the properties of the perovskite material, the improvement is limited. Other approaches increase the entropy value of the perovskite material by increasing the types of cations in it, thereby improving its inherent bulk stability.
[0063] However, the applicant discovered that with the increase in the number of cation types, the overall stability of the perovskite material did not improve significantly as expected. After extensive exploratory research, the applicant realized that although an increased number of cation types is beneficial for improving the entropy value of perovskite materials, the significant differences in ionic radii, atomic diffusion coefficients, and formation energies among different cations lead to a persistent phase segregation problem in perovskite materials. That is, some components in the perovskite material accumulate in localized regions, forming phases different from the overall composition. This results in uneven stress distribution within the perovskite crystal, negatively impacting the bulk stability of the perovskite material and making the increase in entropy ineffective in improving its stability. Furthermore, it causes differences in the physical and chemical properties of the perovskite material across different regions, resulting in decreased uniformity and poor light absorption in localized areas, thus affecting the photoelectric conversion efficiency of perovskite solar cells.
[0064] Through in-depth analysis and research on perovskite materials, this application creatively proposes a perovskite material and its preparation method, perovskite devices, and photovoltaic modules. By synergistically controlling the cation types, cation radii, and cation proportions of three-dimensional perovskite materials, the entropy value of the perovskite material is increased while effectively improving the phase segregation problem. This not only enhances the effect of entropy value on the bulk stability of perovskite materials but also improves the uniformity of three-dimensional perovskite materials by reducing phase segregation. The comprehensive performance of perovskite materials is effectively improved in terms of bulk stability and uniformity, which in turn helps to improve the service life and photoelectric conversion performance of devices using perovskite materials.
[0065] In the first aspect, embodiments of this application provide a perovskite material having a three-dimensional structure. The chemical formula of the perovskite material is ABX3, where A is an A-position cation, B is a B-position cation, and X is an X-position anion.
[0066] Among them, the A-site cation includes at least five different types of cations, one of which is formamidinium cation. The other types of A-site cations include first-type A-site cations with ionic radii smaller than formamidinium cations and second-type A-site cations with ionic radii larger than formamidinium cations. Among the A-site cations, the atomic percentage of first-type A-site cations is greater than that of second-type A-site cations. Among the A-site cations, the atomic percentage of formamidinium cations is 50% to 90%.
[0067] Based on their structural characteristics, perovskite materials can be divided into three-dimensional perovskite materials and two-dimensional perovskite materials. Among them, three-dimensional perovskite materials have better carrier transport performance and a more suitable band structure, making them more suitable as light-absorbing layers. Although two-dimensional perovskite materials have lower photoelectric conversion efficiency, they are more stable than three-dimensional perovskite materials, making them more suitable as passivation layers. When applied to the surface of the light-absorbing layer of a three-dimensional perovskite material, they provide better stability and surface protection for the light-absorbing layer.
[0068] The perovskite material of this application embodiment has a three-dimensional structure, making it more suitable as a light-absorbing layer in perovskite devices to improve photoelectric conversion efficiency. Furthermore, this application embodiment synergistically controls the type, ionic radius, and proportion of A-site cations in this three-dimensional perovskite material, improving both the bulk stability and phase segregation phenomena to enhance its uniformity, thereby achieving a significant improvement in the overall stability of the perovskite material.
[0069] The presence of five or more cations at the A-site increases the entropy of perovskite materials, contributing to greater stability of the three-dimensional perovskite bulk phase. However, with five or more cations, the atomic diffusion coefficients, ionic radii, and formation energies often differ. While this leads to greater stability of the perovskite bulk phase, it also increases the risk of A-site phase segregation and uneven material distribution. Therefore, this application addresses these issues through synergistic control of the ionic radius relationships and content proportions of various cations. Specifically, one of the A-site cations is a formamidinium cation with an atomic proportion of 50%–90%, and at least one of the other A-site cations is a type I A-site cation with an ionic radius smaller than that of the formamidinium cation (also understood as a small-sized A-site cation). By introducing type I A-site cations with ionic radii smaller than that of the formamidinium cation, the tolerance factor of the three-dimensional perovskite material can be improved, lattice distortion reduced, and the stability of the perovskite material enhanced.
[0070] However, if the other A-site cations are all small-sized A-site cations with ionic radii smaller than that of the formamidin cation, it can easily lead to phase segregation at the A-site. Therefore, at least one of the A-site cations in this application is a second-type A-site cation with an ionic radius larger than that of the formamidin cation (which can also be understood as a large-sized A-site cation). By introducing a second-type A-site cation with an ionic radius larger than that of the formamidin cation, in addition to helping to further reduce the formation energy, it can also increase steric hindrance and improve the A-site phase segregation problem caused by the addition of small-sized first-type A-site cations.
[0071] However, if other A-site cations are large-sized A-site cations with ionic radii larger than formamidinium cations, or if the proportion of such large-sized A-site cations is too high, the perovskite material is prone to change from a three-dimensional structure to a two-dimensional structure, or to a mixed structure dominated by a two-dimensional structure. Therefore, in this application embodiment, the A-site cation is mainly formamidinium cation. This is achieved by simultaneously introducing a first type of A-site cation and a second type of A-site cation, and controlling the atomic percentage of the first type of A-site cation to be higher than that of the second type of A-site cation. For example, the atomic percentage of formamidinium cation in the A-site cation is 50%, 60%, 70%, 75%, 80%, 85%, or 90%.
[0072] In this way, by controlling and coordinating the selection of A-site cations, the relationship between ionic radii, and the atomic percentages of the first and second type A-site cations, the bulk stability of three-dimensional perovskite materials can be improved, while the phase segregation problem can be mitigated, the overall uniformity of perovskite materials can be enhanced, and the performance of perovskite materials can be improved more comprehensively.
[0073] It should be noted that the ionic radius reflects the size of the corresponding ion. For example, I - The ionic radius of Br is 220 pm. - The ionic radius of Cl is 196 pm. - The ionic radius is 181 pm. By comparing the ionic radii, we can conclude that the size of the iodide ion > the size of the bromide ion > the size of the chloride ion.
[0074] In addition, atomic percentage refers to the percentage of atoms of a certain element in a chemical substance; it can also be understood as the proportion of that element in the chemical substance. For example, if there are 100 atoms at site A, 5 of them are MA. + 5 are Cs + 5 are Rb + 5 are EDA 2+ 80 are FA + So, in the A-site cation, MA + The atomic percentage is 5%, cesium, rubidium and EDA 2+ The atomic percentages of each are also 5%, FA + The atomic percentage is 80%. This atomic percentage also reflects the proportion of these types of A-site cations at the A-site, i.e., FA. + The A-site cation has the highest content.
[0075] Furthermore, the first type of A-site cation includes at least two types. Adding at least two types of first-type A-site cations can achieve a wide bandgap in perovskite materials while improving the problem of A-site phase segregation. Specifically, to achieve a wide bandgap in perovskite materials, if only one type of first-type A-site cation is used for adjustment, its dosage needs to be increased to achieve the desired bandgap adjustment, which makes A-site phase segregation more likely to occur. However, when this application introduces two or more types of first-type A-site cations, the dosage of each type of first-type A-site cation is relatively reduced, making A-site phase segregation less likely and allowing for better adjustment to achieve the wide bandgap characteristics of the perovskite material.
[0076] Furthermore, the band gap of the perovskite material is 1.65 eV to 1.80 eV. For example, the band gap of the perovskite material is 1.65 eV, 1.68 eV, 1.70 eV, 1.72 eV, 1.75 eV, 1.78 eV or 1.80 eV.
[0077] The aforementioned bandgap perovskite material belongs to the wide-bandgap perovskite material category. Therefore, the three-dimensional perovskite material provided in this application not only has good bulk stability and good material uniformity, but also has the characteristics of a wide bandgap, making it more suitable for combination with some narrow-bandgap materials. For example, it can be used in conjunction with silicon-based cells to manufacture multi-junction tandem solar cells, providing high-efficiency solar cells with promising industrial applications.
[0078] Furthermore, the atomic percentage of the second type A-site cation in the A-site cation is less than or equal to 10%. For example, the atomic percentage of the second type A-site cation in the A-site cation is 10%, 9%, 8%, 6%, 5%, 4%, or 3%. Controlling the atomic percentage of this larger-sized A-site cation (the second type A-site cation) to below 10% is beneficial for better control of perovskite materials, maintaining their effective three-dimensional structure, thereby avoiding or reducing the formation of two-dimensional perovskite structures.
[0079] In addition to optimizing the control of the A-site cation, this application also optimizes the control of the X-site anion. The X-site anion includes at least three different types of halide anions and / or pseudohalogen anions, one of which is I. - Other types of X-site anions include those with ionic radii smaller than I. - Type I X-position anions, ionic radius greater than I - The second type of X-position anion includes at least one type of first type X-position anion and at least one type of second type X-position anion; in the X-position anions, the atomic percentage of the first type X-position anion is greater than the atomic percentage of the second type X-position anion.
[0080] The embodiments of this application synergistically control the type, ionic radius, and proportion of X-site anions in perovskite materials, which can further improve the stability of perovskite materials, improve the X-site phase segregation problem, and ensure the wide bandgap of perovskite.
[0081] The presence of three or more halogen and / or pseudohalogen anions at the X-position can further increase the entropy value of the perovskite material, thus enhancing the bulk phase stability of the three-dimensional perovskite structure. Furthermore, one of the anions at the X-position is I... - The other X-position anions have at least one ionic radius smaller than I. - An ion with a radius greater than I - This reduces the impact of other X-position anions on I. - The differences in ion diffusion coefficients and formation energies can mitigate the problem of X-phase segregation.
[0082] Furthermore, in the X-position anion, I - The atomic percentage is greater than or equal to 50%. For example, in the X-position anion, I... - The atomic percentage is 50%, 60%, 70%, 75%, 80%, 85%, 90%, or 95%. In this application, the X-position anion is represented by I... - Primarily, through the interaction of X-site anions with other ionic radii, both smaller and larger, with I... - The combination of these factors helps to widen the bandwidth while better achieving the overall stability of perovskite materials.
[0083] It should be noted that one approach to adjusting the band gap of perovskite materials to 1.65 eV–1.80 eV involves introducing a non-iodide halogen or pseudo-halogen as the main component at the X-site anion, supplemented by a type I A-site cation smaller than the formamidinium cation. However, this approach easily leads to phase segregation or even phase separation. Taking the preparation of a perovskite layer by coating a cationic solution onto a lead iodide framework layer as an example, since the ion diffusion coefficients of halogens other than iodide ions or pseudo-halogens are significantly different from those of iodide ions, the formation energy of the reaction between halogens other than iodide ions and the lead iodide framework layer is significantly different from that of the reaction between iodide ions and the lead iodide framework layer. Therefore, when using this approach to adjust the band gap, phase segregation and lattice defects (such as vacancy defects) will form in the perovskite layer, affecting the efficiency and stability of perovskite device fabrication.
[0084] The approach to widening the bandgap in this application is to primarily employ at least two types of Type I A-site cations, supplemented by small amounts of other halogens and / or pseudohalogens that introduce non-iodide ions, to mitigate the impact of introducing these types of X-site anions on phase segregation. Through comprehensive regulation of the above aspects, the perovskite material in the embodiments of this application possesses both a wide bandgap and improved overall stability, thereby ensuring that perovskite devices using this material maintain good performance even after prolonged storage.
[0085] Optionally, the first type of A-site cation includes MA. + Cs + K + Ca 2+ Zn 2+ Na + or Rb + At least two of them. Among them, MA + It refers to methylammonium cation.
[0086] Optionally, the second type of A-site cation includes DMA. + BA + PA + AA + BMIM + EA + or EDA 2+ At least one of them. Wherein, DMA + It refers to dimethylammonium carbamate cation, BA + It refers to n-butylammonium cation, PA + It refers to propylammonium cation, AA + It refers to propylene ammonium cation, BMIM + It refers to the 1-butyl-3-methylimidazolium cation, EA + It refers to ethylammonium ion, EDA 2+ It refers to the divalent cation of ethylenediamine.
[0087] Introducing MA + In the case of [unclear context], it is prone to rapid volatilization during the annealing and crystallization process of perovskite materials, leading to crystallization defects; the introduction of Cs + or Rb + In the case of alkali metal ions, these alkali metal ions react with FA. + Significant differences exist in ion diffusion coefficients and formation energies, which easily lead to phase segregation. By introducing a second type of A-site cation, the aforementioned crystallization defects and phase segregation problems can be effectively improved, and it works synergistically with the first type of A-site cation.
[0088] Optionally, the B-site cation includes Pb. 2+ Ga 2+ and Sn2+ At least one of them.
[0089] Optionally, the first type of X-position anion includes F - ,Br - Cl - At least one of them.
[0090] Optionally, the second type of X-position anion includes SCN. - OCN - BF4 - TFSI - CF3 - CF3CO2 - COO - or SO3H - At least one of them.
[0091] Preferably, the chemical formula of the perovskite material is (FA). a1 DMA a2 MA a3 PA a4 Cs a5 Rb a6 )PbI3, a1:a2:a3:a4:a5:a6=(50~90):(0.5~5):(3~22):(1~6):(1~16):(0.5~10).
[0092] Preferably, the chemical formula of the perovskite material is (FA). a1 DMA a2 MA a3 PA a4 Cs a5 Rb a6 )Pb(I b1 Cl b2 Br b3 ), a1:a2:a3:a4:a5:a6=(50~90):(0.5~5):(3~22):(1~6):(1~16):(0.5~10), b1:b2:b3=(70~95):(0.5~8):(3~25).
[0093] Preferably, the chemical formula of the perovskite material is (FA). a1 DMA a2 MA a3 PA a4 Cs a5 Rb a6 )Pb(I b1 Cl b2 Br b3 OCN b4 SCN b5), a1:a2:a3:a4:a5:a6=(50~90):(0.5~5):(3~22):(1~6):(1~16):(0. 5~10), b1:b2:b3:b4:b5=(70~90):(0.5~6):(2~20):(0.5~8):(0.5~8).
[0094] The aforementioned three-dimensional perovskite materials can simultaneously meet the following requirements: wide bandgap to match the requirements of tandem cells with narrow bandgap materials (such as crystalline silicon bottom cells), good perovskite bulk phase stability, and high material uniformity to meet the performance requirements of perovskite devices.
[0095] Secondly, embodiments of this application also provide a method for preparing the perovskite material described in the first aspect, comprising the following steps:
[0096] A cationic solution was coated onto the framework layer and annealed to obtain a perovskite material.
[0097] The framework layer includes at least B-site cations and X-site anions, and the cation solution includes some or all of the A-site cations.
[0098] It is understandable that the framework layer must include at least a B-site cation and an X-site anion, meaning that the framework layer can be composed of B-site cations and X-site anions, or it can be a framework layer composed of B-site cations and X-site anions with some A-site cations. For example, the B-site cation is Pb. 2+ The X-position anion is I - The framework layer can be a PbI2 framework layer, or it can be a PbI2 framework layer incorporating some types of A-site cations. Furthermore, a cation solution including some or all A-site cations means that the cation solution can include all types of A-site cations, or it can include only some types of A-site cations, with the other types of A-site cations placed in the framework layer, so that all A-site cations can participate in their reaction with the framework layer.
[0099] This application employs a two-step method to fabricate perovskite materials, suitable for preparing perovskite materials with textured surface conformability requirements. In other words, it can obtain perovskite materials with comprehensive stability while meeting the production requirements of textured, conformable perovskite materials. For example, when applied to solar cells with textured surfaces, it not only provides a perovskite light-absorbing layer with good overall stability, improving light utilization efficiency, but also meets the needs of industrial production.
[0100] Furthermore, the surface of the skeleton layer has a velvety texture.
[0101] Furthermore, the thickness of the perovskite film is 500 nm to 2000 nm. For example, the thickness of the perovskite film can be 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm, 1500 nm, 1600 nm, 1700 nm, 1800 nm, 1900 nm, or 2000 nm, or the thickness of the perovskite film can be between any two of the above thicknesses.
[0102] Furthermore, the A-site cation is divided into alkali metal cation and organic cation. Before the step of coating the cation solution on the framework layer, the preparation method of perovskite material also includes the following steps:
[0103] Preparation of the framework layer: The material source containing alkali metal cations, the material source containing B-site cations, and the material source containing X-site anions are co-deposited by vapor deposition to obtain the framework layer;
[0104] Preparation of cationic solution: Dissolve organic cations in a green organic solvent, which includes at least one of ethanol and isopropanol.
[0105] Understandably, based on ionic radius, A-site cations include formamidinium cations, first-class A-site cations with ionic radii smaller than formamidinium cations, and second-class A-site cations with ionic radii larger than formamidinium cations. Classified by the nature of organic or inorganic compounds, A-site cations include alkali metal cations and organic cations.
[0106] To increase the entropy of the A-site cation, this application allows for the selection of different alkali metal cations and organic cations as first-type and second-type A-site cations based on the required ionic radius. In the two-step preparation of perovskite materials, the alkali metal cations are co-evaporated into the framework layer, while the cation solution only includes organic cations with good compatibility in the organic solvent. This ensures that both alkali metal cations and organic cations can participate in the perovskite material formation reaction according to preset amounts, avoiding the problem of poor solubility of alkali metal cations in organic solvents and the inability to use a large amount in the reaction. Furthermore, since the alkali metal cations are co-evaporated into the framework layer, the amount and distribution of the alkali metal cations in the framework layer can be flexibly adjusted according to requirements; similarly, since the organic cations have good compatibility in organic solvents, their amount can be flexibly adjusted according to requirements.
[0107] Furthermore, the aforementioned organic solvent includes at least one of ethanol and isopropanol. These solvents are green organic solvents, which means that the preparation process of this application embodiment not only meets the requirements for maintaining the texture of perovskite materials and is suitable for industrial production, but also has the advantages of being green and environmentally friendly.
[0108] Preferably, in the step of preparing the framework layer, PbI2, CsBr, and RbBr are co-deposited at a deposition rate ratio of (8-12):(0.5-2.2):(0.1-1.2) to obtain a lead iodide framework layer containing alkali metal inorganic salts, and the thickness of the framework layer is 300 nm to 750 nm. For example, the thickness of the framework layer can be 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, or 750 nm, or the thickness of the framework layer can be between any two of the above thicknesses.
[0109] Preferably, in the step of preparing the cationic solution, FAI, DMAI, MAI, MACl and PACl are dissolved in isopropanol in an atomic percentage of (70-90):(3-12):(8-12):(8-22):(3-12) to obtain the cationic solution.
[0110] Preferably, in the step of coating the cation solution onto the framework layer, the FA content at the A-site cation is... + :DMA + :MA + :PA + :Cs + :Rb + The atomic percentages are (70~90):(3~6):(6~18):(2~6):(4~6):(2~5) for coating.
[0111] Different types of ions have different volatilization rates during high-temperature annealing, resulting in changes in their content. Therefore, the above-mentioned optimized scheme further ensures that the final perovskite light-absorbing layer can obtain better performance.
[0112] Thirdly, this application also provides a perovskite device comprising the perovskite material as described in the first aspect, or the perovskite device comprising the perovskite material prepared by the preparation method described in the second aspect.
[0113] Optionally, the perovskite device includes at least one of a perovskite solar cell, a perovskite light-emitting diode, or a perovskite laser. Preferably, the perovskite device is a perovskite solar cell, which includes a perovskite tandem solar cell or a perovskite single-junction solar cell.
[0114] In one optional embodiment, the perovskite device is a perovskite tandem solar cell. Referring to Figure 1, the perovskite tandem solar cell includes: a base cell 1 with a planar or textured surface; an electron-hole recombination layer 2, a first transport layer 31, a perovskite light-absorbing layer 4, a second transport layer 32, and a transparent conductive layer 5 sequentially disposed on the surface of the base cell 1; a first electrode 61 electrically contacting the transparent conductive layer 5; and a second electrode 62 electrically contacting the base cell 1. Specifically, one of the first transport layer 31 and the second transport layer 32 is an electron transport layer, and the other is a hole transport layer; one of the first electrode 61 and the second electrode 62 is a positive electrode, and the other is a negative electrode; the perovskite light-absorbing layer 4 comprises the perovskite material mentioned in the first or second aspect above.
[0115] The following section provides a further explanation of the film layers in perovskite tandem solar cells.
[0116] The bottom cell 1 includes at least one of crystalline silicon bottom cell 1, copper indium gallium selenide bottom cell 1, perovskite narrow bandgap bottom cell 1, or organic bottom cell 1.
[0117] The electron-hole recombination layer 2 is made of at least one of IZO and ITO; its thickness is 2 nm to 30 nm. For example, the thickness of the electron-hole recombination layer 2 can be 2 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, or 30 nm, or it can be between any two of the above thicknesses. The hole transport layer is made of nickel oxide; its thickness is 5 nm to 30 nm. For example, the thickness of the hole transport layer can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, or 30 nm, or it can be between any two of the above thicknesses. The perovskite light-absorbing layer 4 has a thickness of 500 nm to 2000 nm. For example, the thickness of the perovskite light-absorbing layer 4 can be 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm, 1500 nm, 1600 nm, 1700 nm, 1800 nm, 1900 nm, or 2000 nm, or the thickness of the perovskite light-absorbing layer 4 can be between any two of the above thicknesses. The material of the electron transport layer includes C. 60The thickness of the electron transport layer is 5 nm to 30 nm. For example, the thickness of the electron transport layer can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, or 30 nm, or the thickness of the electron transport layer can be between any two of the above thicknesses. The material of the transparent conductive layer 5 includes at least one of ITO, IZO, or IWO; the thickness of the transparent conductive layer 5 is 30 nm to 150 nm. For example, the thickness of the transparent conductive layer 5 can be 30 nm, 50 nm, 80 nm, 100 nm, 120 nm, or 150 nm, or the thickness of the transparent conductive layer 5 can be between any two of the above thicknesses. The material of the electrode includes at least one of gold, silver, copper, or aluminum; the thickness of the electrode is 50 nm to 400 nm. For example, the thickness of the electrode can be 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, or 400 nm, or the thickness of the electrode can be between any two of the above thicknesses.
[0118] In addition to the structure described above, perovskite tandem solar cells may also include other functional films, including:
[0119] A hole-modifying layer 7 is disposed between the hole transport layer and the perovskite light-absorbing layer 4. The material of the hole-modifying layer 7 is a single-molecule self-assembled material, including at least one of 2PACz, 4PACz, or MeO-2PACz; and / or
[0120] A passivation layer 8 is disposed between the perovskite light-absorbing layer 4 and the second transport layer 32. The material of the passivation layer 8 includes LiF or a two-dimensional perovskite material, and the thickness of the passivation layer 8 is 0.5 nm to 5 nm; for example, the thickness of the passivation layer 8 can be 0.5 nm, 1 nm, 1.5 nm, 3 nm, 3.5 nm, 4 nm, or 5 nm, or the thickness of the passivation layer 8 can be between any two of the above thicknesses. And / or,
[0121] A buffer layer 9 is disposed between the second transmission layer 32 and the transparent conductive layer 5. The thickness of the buffer layer 9 is 5 nm to 30 nm; for example, the thickness of the buffer layer 9 can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, or 30 nm, or the thickness of the buffer layer 9 can be between any two of the above thicknesses. And / or,
[0122] An antireflection layer 10 is disposed on the side of the transparent conductive layer 5 facing away from the second transmission layer 32, and the thickness of the antireflection layer 10 is 80 nm to 150 nm. For example, the thickness of the antireflection layer 10 can be 80 nm, 100 nm, 120 nm, or 150 nm, or the thickness of the antireflection layer 10 can be between any two of the above thicknesses.
[0123] Among them, 2PACz, 4PACz or MeO-2PACz are all derivatives of carbazole phosphonic acid (PACz).
[0124] In another optional embodiment, the perovskite device is a perovskite single-junction solar cell. The perovskite single-junction solar cell includes: a transparent conductive substrate with a planar or textured surface; a first transport layer, a perovskite light-absorbing layer, and a second transport layer sequentially disposed on the transparent conductive substrate; a first electrode electrically in contact with the second transport layer; and a second electrode electrically in contact with the transparent conductive substrate. Specifically, one of the first and second transport layers is an electron transport layer and the other is a hole transport layer; one of the first and second electrodes is a positive electrode and the other is a negative electrode; and the perovskite light-absorbing layer comprises the perovskite material mentioned in the first or second aspect above.
[0125] Fourthly, embodiments of this application provide a photovoltaic module, which includes a solar cell, the solar cell including a perovskite light-absorbing layer, the perovskite light-absorbing layer including the perovskite material as described in the first aspect, or the perovskite light-absorbing layer including the perovskite material prepared by the preparation method described in the second aspect.
[0126] The embodiments of this application will be further described below with reference to specific examples and test results.
[0127] Example 1
[0128] This embodiment provides a perovskite tandem solar cell, which is prepared by the following method:
[0129] HJT crystalline silicon solar cells with a textured surface are provided as bottom cells;
[0130] A 20 nm thick IZO layer was fabricated on the bottom cell as an electron-hole recombination layer;
[0131] A hole transport layer and a hole modification layer were sequentially prepared on the electron-hole composite layer. The hole transport layer was a NiOx layer with a thickness of 20 nm, and the hole modification layer was a single-molecule self-assembled material 4PACz.
[0132] Preparation of a perovskite light-absorbing layer on a hole-modified layer:
[0133] Preparation of lead iodide framework layer: PbI2, CsBr and RbBr materials were co-deposited using a vacuum thermal evaporation coating instrument at a deposition rate ratio of 10:1:1 to obtain an alkali metal inorganic salt lead iodide framework layer with a thickness of 550 nm.
[0134] Preparation of cationic solution: FAI, DMAI, MAI, MACl and PACl are dissolved in isopropanol to obtain cationic solution;
[0135] A cationic solution was coated onto the framework layer and annealed to obtain a perovskite light-absorbing layer with a thickness of 850 nm; wherein the A-site cations contain FA atoms with an atomic percentage of approximately 84:2:4:2:5:3. + DMA + MA + PA + 、(Cs + and Rb + MA + Cs + and Rb + Compared to FA + The ionic radius is small, DMA + and PA + Compared to FA + The ionic radius is large; the X-position anion includes I atoms with an atomic percentage of approximately 80:15:5. - ,Br - Cl - ;
[0136] A 1 nm thick LiF layer was prepared on the perovskite light-absorbing layer as a passivation layer;
[0137] A C layer with a thickness of 20 nm was fabricated on the passivation layer. 60 As an electron transport layer;
[0138] A 20 nm buffer layer was fabricated on the electron transport layer;
[0139] A transparent conductive layer, an antireflective layer, and an electrode are sequentially fabricated on a buffer layer; wherein the transparent conductive layer is an ITO layer with a thickness of 100 nm, the antireflective layer has a thickness of 100 nm, and the electrode material is silver with a thickness of 200 nm.
[0140] Examples 2 to 6
[0141] The difference from Example 1 is that the types and ratios of cations at the A site and the X site are different, resulting in a perovskite tandem solar cell, as detailed in Table 1.
[0142] Comparative Example 1
[0143] This comparative example provides a perovskite tandem solar cell. The difference between this comparative example and Example 1 is that the types of A-site cations are different. The A-site cations in this comparative example only include formamidinium cations and first-type A-site cations with ionic radii smaller than formamidinium cations, and do not include second-type A-site cations with ionic radii larger than formamidinium cations. The perovskite tandem solar cell is finally obtained, as detailed in Table 1.
[0144] Comparative Example 2
[0145] This comparative example provides a perovskite tandem solar cell. The difference between this comparative example and Example 1 is that the types of A-site cations are different. The A-site cations in this comparative example only include formamidinium cations and second-type A-site cations with ionic radii larger than formamidinium cations, and do not include first-type A-site cations with ionic radii smaller than formamidinium cations. The perovskite tandem solar cell is finally obtained, as detailed in Table 1.
[0146] Comparative Example 3
[0147] This comparative example provides a perovskite tandem solar cell. The difference between this comparative example and Example 1 is that the atomic percentage of the first type of A-site cation is less than that of the second type of A-site cation in the A-site cation, and a perovskite tandem solar cell is finally obtained. See Table 1 for details.
[0148] Comparative Examples 4 to 5
[0149] The difference from Example 1 is that FA + The proportion of each component used varies, resulting in perovskite tandem solar cells, as detailed in Table 1.
[0150] Table 1. Perovskite materials of examples and comparative examples
[0151] Note 1: " / " indicates that the component does not exist;
[0152] 2. Atomic percentage refers to the atomic percentage of each component in the order listed in Table 1. Taking Example 1 as an example, the order of the A-site cations listed in Table 1 is FA. + MA + Cs + 、Rb + DMA + PA + Then the atomic percentage refers to FA + MA + :Cs + :Rb + DMA + PA + The atomic percentages are 84:4:5:3:2:2.
[0153] Performance testing:
[0154] The perovskite film layers in the tandem solar cells of the above embodiments and comparative examples were subjected to quantitative chemical composition analysis using XPS (X-ray photoelectron spectroscopy). The XPS equipment used was the EscaLab Xi manufactured by Thermo Fisher Scientific, UK. +The test was conducted using a micro-area selective testing mode, with a test area of 10 μm × 10 μm. The chemical composition test results of the perovskite in the above examples and comparative examples are shown in Table 2 below.
[0155] For the perovskite tandem solar cells in the above embodiments and comparative examples, performance tests were conducted using a Halm testing and sorting system to assess open-circuit voltage, fill factor, and photoelectric conversion efficiency. The Halm system, a device that simulates sunlight, is equipped with an electronic load, data acquisition, and computation equipment to test the electrical performance of photovoltaic devices (including solar cells). The calibrated light intensity of the solar cells under test was controlled at 1000 ± 5 W / m². 2 .
[0156] Stability test: After the perovskite tandem solar cells tested with the Halm test and sorting equipment are placed for 3000 hours, the photoelectric conversion efficiency is tested again, and the retention rate of photoelectric conversion efficiency is calculated as: (photoelectric conversion efficiency after 3000 hours / initial photoelectric conversion efficiency) × 100%.
[0157] The performance test results of the tandem solar cell devices in the above embodiments and comparative examples are shown in Table 3 below.
[0158] Table 2. Results of perovskite chemical composition tests for the examples and comparative examples.
[0159] Table 3 shows the initial efficiency and 3000-hour stability test results for the examples and comparative examples.
[0160] Comparing the experimental results of Examples 1 to 3 and Comparative Examples 1 to 3, it can be seen that when the A-site cation does not contain a second type of A-site cation with an ionic radius larger than that of the formamidinium cation, or when the A-site cation does not contain a first type of A-site cation with an ionic radius smaller than that of the formamidinium cation, or when the A-site cation includes both first and second type A-site cations, but the atomic percentage of the second type of A-site cation is greater than that of the first type of A-site cation, the resulting perovskite light-absorbing layer does not help improve the photoelectric conversion efficiency of the solar cell. It is evident that simply increasing the entropy value by increasing the variety of A-site cations is insufficient to effectively improve the overall stability of the perovskite material, and therefore does not significantly contribute to the performance improvement of the solar cell with the perovskite light-absorbing layer. Only by adopting the approach of the embodiments of this application, which both increases the entropy value by increasing the variety of A-site cations and controls the ionic radius and atomic percentage of each A-site cation, can the overall stability of the perovskite material be more effectively ensured, preventing significant phase segregation and thus more effectively promoting the improvement of the photoelectric conversion efficiency of the solar cell.
[0161] Further comparison of Example 1 and Comparative Example 4 shows that the solar cell of Example 1 has better photoelectric conversion efficiency. This demonstrates that, based on improving the A-site cation, appropriate adjustment of the FA... + An ion content (not less than 50%) helps to further improve the overall stability of perovskite materials and also helps to further promote the improvement of photovoltaic conversion efficiency of solar cells. Because FA + If the content is too low, to maintain the wide-bandgap perovskite required for tandem solar cells, the content of A-site type I and type II A-site cations needs to be increased, leading to phase segregation, poor tolerance factor, and structural instability. However, FA + Excessive content necessitates reducing the content of type I and type II A-site cations and increasing the Br content in the X-site anion to maintain the wide-bandgap perovskite required for tandem solar cells. - and Cl - Equal content leads to phase segregation and poor tolerance factor, resulting in structural instability. Further comparison of Example 1 and Example 2 shows that the solar cell of Example 1 has better photoelectric conversion efficiency. This demonstrates that using two or more type I A-site cations is more helpful in improving the overall stability of perovskite materials, thereby facilitating more effective improvement of the relevant performance of solar cells.
[0162] Further comparison of Examples 1 and 3 shows that the solar cell of Example 1 has a better photoelectric conversion efficiency. It is evident that further controlling the atomic percentage of the second type A-site cation to below 10% is more helpful in improving the overall stability of the perovskite material, thereby facilitating a more effective improvement in the relevant performance of the solar cell.
[0163] Further comparison of Examples 1 and 4 shows that the solar cell of Example 4 has a better photoelectric conversion efficiency. This demonstrates that, based on improving the A-site cation, further optimizing the X-site anion by controlling its composition, ionic radius, and dosage helps to further improve the overall stability of the perovskite material and also helps to further promote the improvement of the photoelectric conversion efficiency of the solar cell.
[0164] Further comparison of Examples 1 and 5 shows that the solar cell of Example 1 has better photoelectric conversion efficiency. It is evident that, based on improvements to the A-site cation, the X-site anion regulation is highly sensitive. When halogens with lower formation energies, bromine and chlorine, are over-substituted (the sum of the atomic numbers of bromine and chlorine exceeds the atomic number of iodine) for iodine halide, phase segregation easily occurs in the perovskite, leading to a decrease in the overall stability of the perovskite material and consequently a decrease in the photoelectric conversion efficiency of the solar cell.
[0165] Further comparison of Examples 5 and 6 shows that the solar cell of Example 6 has better photoelectric conversion efficiency. It is evident that, based on improvements to the A-site cation, the X-site anion regulation is highly sensitive. When the sum of the atomic numbers of bromine and chlorine does not exceed the atomic number of iodine, the perovskite phase segregation problem is significantly improved, thereby enhancing the overall stability of the perovskite material and further contributing to the improvement of the solar cell's photoelectric conversion efficiency.
[0166] The technical solutions disclosed in the embodiments of this application have been described in detail above. Specific examples have been used in this article to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A perovskite material, characterized in that, The perovskite material has a three-dimensional structure, and the chemical formula of the perovskite material is ABX3, where A is an A-position cation, B is a B-position cation, and X is an X-position anion; The A-site cation includes at least five different types of cations, one of which is a formamidinium cation. The other types of A-site cations include first-type A-site cations with ionic radii smaller than that of the formamidinium cation and second-type A-site cations with ionic radii larger than that of the formamidinium cation. Among the A-site cations, the atomic percentage of the first-type A-site cations is greater than that of the second-type A-site cations. Among the A-site cations, the atomic percentage of the formamidinium cation is 50% to 90%.
2. The perovskite material according to claim 1, characterized in that, The first type of A-site cation includes at least two kinds.
3. The perovskite material according to claim 1 or 2, characterized in that, The band gap of the perovskite material is 1.65 eV to 1.80 eV.
4. The perovskite material according to any one of claims 1 to 3, characterized in that, The atomic percentage of the second type of A-site cation in the A-site cation is less than or equal to 10%.
5. The perovskite material according to any one of claims 1 to 4, characterized in that, The X-position anion includes at least three different types of halide anions and / or pseudohalogen anions, wherein one of the X-position anions is I. - Other types of X-position anions include those with ionic radii smaller than that of the I-position anion. - The first type of X-position anion, with an ionic radius greater than that of the I - The second type of X-position anion, wherein the first type of X-position anion includes at least one type, and the second type of X-position anion includes at least one type; wherein the atomic percentage of the first type of X-position anion is greater than the atomic percentage of the second type of X-position anion.
6. The perovskite material according to any one of claims 1 to 5, characterized in that, The first type of A-site cation includes MA + Cs + K + Ca 2+ Zn 2+ Na + or Rb + At least two of them; and / or, The second type of A-site cation includes DMA. + BA + PA + AA + BMIM + EA + or EDA 2+ At least one of them; and / or, The B-site cation includes Pb. 2+ Ga 2+ and Sn 2+ At least one of them; and / or, The X-position anion includes I - Ionic radius is smaller than that of I - The first type of X-position anion, with an ionic radius greater than that of the I - The second type of X-position anion, wherein the first type of X-position anion includes F - ,Br - Cl - At least one of them, wherein the second type of X-position anion includes SCN. - OCN - BF4 - TFSI - CF3 - CF3CO2 - COO - or SO3H - At least one of the following, in the X-position anion, the I - The atomic percentage is greater than or equal to 50%.
7. The perovskite material according to any one of claims 1 to 6, characterized in that, The chemical formula of the perovskite material is (FA). a1 DMA a2 MA a3 PA a4 Cs a5 Rb a6 PbI3, a1:a2:a3:a4:a5:a6=(50~90):(0.5~5):(3~22):(1~6):(1~16):(0.5~10); or, The chemical formula of the perovskite material is (FA). a1 DMA a2 MA a3 PA a4 Cs a5 Rb a6 )Pb(I b1 Cl b2 Br b3 ), a1:a2:a3:a4:a5:a6=(50~90):(0.5~5):(3~22):(1~6):(1~16):(0.5~10), b1:b2:b3=(70~95):(0.5~8):(3~25); or, The chemical formula of the perovskite material is (FA). a1 DMA a2 MA a3 PA a4 Cs a5 Rb a6 )Pb(I b1 Cl b2 Br b3 OCN b4 SCN b5 ), a1:a2:a3:a4:a5:a6=(50~90):(0.5~5):(3~22):(1~6):(1~16):(0. 5~10), b1:b2:b3:b4:b5=(70~90):(0.5~6):(2~20):(0.5~8):(0.5~8).
8. A method for preparing a perovskite material, characterized in that, The perovskite material comprises the perovskite material as described in any one of claims 1 to 7, and the method for preparing the perovskite material comprises the following steps: A cationic solution is coated onto the framework layer, and then annealed to obtain the perovskite material. The framework layer includes at least the B-site cation and the X-site anion, and the cation solution includes some or all of the A-site cation.
9. The preparation method according to claim 8, characterized in that, The surface of the skeleton layer has a velvety structure; and / or, The thickness of the perovskite film is 500 nm to 2000 nm; and / or, The A-site cation is divided into alkali metal cation and organic cation. Before the step of coating the cation solution on the framework layer, the method for preparing the perovskite material further includes the following steps: Preparation of the framework layer: The material source containing the alkali metal cation, the material source containing the B-site cation, and the material source containing the X-site anion are co-deposited by vapor deposition to obtain the framework layer; Preparation of the cation solution: Dissolve the organic cation in an organic solvent.
10. The preparation method according to claim 9, characterized in that, In the step of preparing the framework layer, PbI2, CsBr, and RbBr are co-deposited at a deposition rate ratio of (8-12):(0.5-2.2):(0.1-1.2) to obtain a lead iodide framework layer containing alkali metal inorganic salts, the thickness of which is 300 nm-750 nm; and / or, In the step of preparing the cationic solution, FAI, DMAI, MAI, MACl, and PACl are dissolved in isopropanol in an atomic percentage ratio of (70–90):(3–12):(8–12):(8–22):(3–12) to obtain the cationic solution; and / or, In the step of preparing the cationic solution, the organic solvent includes at least one selected from ethanol and isopropanol; and / or, In the step of coating the cation solution onto the framework layer, according to the FA in the A-site cation... + :DMA + :MA + :PA + :Cs + :Rb + The atomic percentages are (70~90):(3~6):(6~18):(2~6):(4~6):(2~5) for coating.
11. A perovskite device, characterized in that, The perovskite device comprises the perovskite material as described in any one of claims 1 to 7, or the perovskite device comprises the perovskite material prepared by the preparation method as described in any one of claims 8 to 10.
12. The perovskite device according to claim 11, characterized in that, The perovskite device includes at least one of a perovskite solar cell, a perovskite light-emitting diode, or a perovskite laser.
13. The perovskite device according to claim 11 or 12, characterized in that, The perovskite device is a perovskite tandem solar cell, which includes: a bottom cell with a planar or textured surface; an electron-hole recombination layer, a first transport layer, a perovskite light-absorbing layer, a second transport layer, and a transparent conductive layer sequentially disposed on the surface of the bottom cell; a first electrode electrically in contact with the transparent conductive layer; and a second electrode electrically in contact with the bottom cell; wherein, one of the first transport layer and the second transport layer is an electron transport layer and the other is a hole transport layer; one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode; and the perovskite light-absorbing layer comprises the perovskite material. Alternatively, the perovskite device is a perovskite single-junction solar cell, which includes: a transparent conductive substrate with a planar or textured surface; a first transport layer, a perovskite light-absorbing layer, and a second transport layer sequentially disposed on the transparent conductive substrate; a first electrode electrically in contact with the second transport layer; and a second electrode electrically in contact with the transparent conductive substrate; wherein, one of the first transport layer and the second transport layer is an electron transport layer and the other is a hole transport layer; one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode; and the perovskite light-absorbing layer comprises the perovskite material.
14. The perovskite device according to claim 13, characterized in that, The perovskite device is the perovskite tandem solar cell, and the base cell includes at least one of crystalline silicon base cells, copper indium gallium selenide base cells, perovskite narrow bandgap base cells, or organic base cells; and / or, The electron-hole recombination layer is made of at least one of IZO and ITO; and / or, The thickness of the electron-hole recombination layer is 2nm to 30nm; The hole transport layer is made of nickel oxide; and / or, The thickness of the hole transport layer is 5 nm to 30 nm; and / or, The thickness of the perovskite light-absorbing layer is 500 nm to 2000 nm; and / or, The material of the electron transport layer includes C. 60 ; and / or, The thickness of the electron transport layer is 5 nm to 30 nm; and / or, The material of the transparent conductive layer includes at least one of ITO, IZO, or IWO; and / or, The thickness of the transparent conductive layer is 30nm to 150nm; and / or, The electrode is made of at least one of gold, silver, copper, or aluminum; and / or, The thickness of the electrode is 50 nm to 400 nm.
15. The perovskite device according to claim 13, characterized in that, The perovskite device is the perovskite tandem solar cell, and the perovskite tandem solar cell further includes: A hole-modifying layer is disposed between the hole transport layer and the perovskite light-absorbing layer. The material of the hole-modifying layer is a single-molecule self-assembled material, including at least one of 2PACz, 4PACz, or MeO-2PACz; and / or... A passivation layer is disposed between the perovskite light-absorbing layer and the second transmission layer. The material of the passivation layer includes LiF or a two-dimensional perovskite material, and the thickness of the passivation layer is 0.5 nm to 5 nm; and / or, A buffer layer is disposed between the second transport layer and the transparent conductive layer, the thickness of the buffer layer being 5 nm to 30 nm; and / or, An antireflection layer is disposed on the side of the transparent conductive layer opposite to the second transmission layer, and the thickness of the antireflection layer is 80nm to 150nm.
16. A photovoltaic module, characterized in that, The photovoltaic module includes a solar cell, the solar cell includes a perovskite light-absorbing layer, the perovskite light-absorbing layer includes the perovskite material as described in any one of claims 1 to 7, or the perovskite light-absorbing layer includes the perovskite material prepared by the preparation method as described in any one of claims 8 to 10.