Perovskite solar cell and preparation method thereof, photovoltaic module

Abstract

This application relates to the field of solar cells, disclosing a perovskite solar cell, its fabrication method, and a photovoltaic module. The perovskite solar cell includes a hole transport layer, a perovskite layer, and a self-assembled monolayer located between the hole transport layer and the perovskite layer. The material of the self-assembled monolayer includes a self-assembled monomolecule material, the functional groups of which include an organic oxyacid group and a methoxyphenyl group, wherein -(CH2) is attached to the methoxyphenyl group and the organic oxyacid group, respectively. n - where n is a positive integer greater than or equal to 2. The self-assembled monolayer in this perovskite solar cell possesses elastic properties, effectively coping with abrupt changes in interfacial stress.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a perovskite solar cell and its preparation method, as well as a photovoltaic module. Background Technology

[0002] In perovskite solar cells, MeO-2PACz or MeO-4PACz-like layer structures placed between the perovskite layer and the hole transport layer can effectively improve the problem of poor energy level matching between the perovskite layer and the hole transport layer. However, the connection performance between this type of material and the perovskite layer and the hole transport layer is poor, making it difficult to effectively cope with sudden changes in interface stress. Summary of the Invention

[0003] This invention discloses a perovskite solar cell and its preparation method, as well as a photovoltaic module. The self-assembled monolayer in the perovskite solar cell has elastic properties and can effectively cope with sudden changes in interfacial stress.

[0004] In a first aspect, this application discloses a perovskite solar cell, the perovskite solar cell comprising a hole transport layer, a perovskite layer, and a self-assembled monolayer located between the hole transport layer and the perovskite layer; The material in the self-assembled monolayer includes a self-assembled monomolecule material, the functional groups of which include an organic oxyacid group and a methoxyphenyl group, wherein -(CH2) is attached to the methoxyphenyl group and the organic oxyacid group, respectively. n - where n is a positive integer greater than or equal to 2.

[0005] Furthermore, n is 2 to 6.

[0006] Furthermore, the ratio of the thickness of the hole transport layer, the thickness of the self-assembled monolayer, and the thickness of the perovskite layer is (5:1:200) to (5:1:150).

[0007] Furthermore, the thickness of the hole transport layer is 15 nm to 30 nm; and / or, The thickness of the perovskite layer is 600 nm to 900 nm; and / or, The thickness of the self-assembled monolayer is 3 nm to 6 nm.

[0008] Furthermore, the organic oxyacid groups include carboxylic acid groups and / or phosphonic acid groups.

[0009] Further, the self-assembled monomolecular material is 2-(9H-carbazole-9-)phospho-9-ethyl-4-methoxyphenyl; and / or, The hole transport layer is at least one of a nickel oxide layer, a molybdenum oxide layer, and a vanadium oxide layer; and / or, The relative molecular mass of the self-assembled monomolecule material is 400~600.

[0010] Furthermore, the perovskite solar cell is a tandem cell, comprising a substrate, the substrate including a bottom cell and an electron-hole recombination layer disposed on the bottom cell, the perovskite solar cell further including a first transport layer disposed on the side of the electron-hole recombination layer opposite to the bottom cell, the perovskite layer disposed on the side of the first transport layer opposite to the electron-hole recombination layer, the perovskite solar cell further including a second transport layer and a transparent conductive layer sequentially disposed on the side of the perovskite layer opposite to the first transport layer, the perovskite solar cell further including electrodes, the electrodes including a first electrode and a second electrode, the first electrode being in ohmic contact with the transparent conductive layer, and the second electrode being in ohmic 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, and one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode; Alternatively, the perovskite solar cell is a single-junction cell. The perovskite solar cell includes a substrate, which comprises a glass substrate and a transparent conductive oxide layer. The transparent conductive oxide layer is disposed on the surface of the glass substrate. The perovskite solar cell further includes a first transport layer, which is disposed on a portion of the transparent conductive oxide layer facing away from the glass substrate. The perovskite layer is disposed on the side of the first transport layer facing away from the transparent conductive oxide layer. The perovskite solar cell further includes a second transport layer disposed on the side of the perovskite layer facing away from the first transport layer. The perovskite solar cell also includes electrodes, which include a first electrode and a second electrode. The first electrode is in ohmic contact with the second transport layer. The second electrode is disposed on a portion of the transparent conductive oxide layer facing away from the glass substrate and is in ohmic contact with the transparent conductive oxide layer. The second electrode and the first transport layer are separated by an isolation region. 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.

[0011] Secondly, this application discloses a method for preparing a perovskite solar cell, the method comprising the following steps: A self-assembled monolayer is prepared between a hole transport layer and a perovskite layer; wherein the material of the self-assembled monolayer includes a self-assembled monomolecule material, the functional groups of which include an organic oxyacid group and a methoxyphenyl group, wherein the methoxyphenyl group is attached with a -(CH2) group. n - The organic oxyacid group is attached with -(CH2). n - where n is a positive integer greater than or equal to 2; Post-processing yields perovskite solar cells as described in any of the first aspects.

[0012] Furthermore, the preparation method includes the following steps: The self-assembled monomolecular material is coated on the hole transport layer and then subjected to a first annealing process to obtain the self-assembled monomolecular layer. The perovskite layer is prepared on the self-assembled monolayer.

[0013] Further, the mass concentration of the self-assembled monomolecule material is 0.8 mg / mL to 1.2 mg / mL; and / or, In the first annealing step, the annealing temperature is 90℃~110℃, and the time is 5 min~15 min; and / or, The coating speed is 3000 rpm to 4500 rpm.

[0014] Further, the step of preparing the perovskite layer on the self-assembled monolayer includes: A lead halide framework layer was prepared on the self-assembled monolayer; A cationic solution is coated onto the lead halide framework layer, followed by a second annealing process to obtain the perovskite layer.

[0015] Furthermore, in the second annealing step, the annealing temperature is 120℃~140℃, and the annealing time is 20 min~40 min.

[0016] Thirdly, this application discloses a photovoltaic module, which includes: the solar cell described in any one of the first aspects, or the solar cell prepared by the preparation method described in any one of the second aspects.

[0017] Compared with the prior art, the beneficial effects of this application are as follows: This application provides a perovskite solar cell and its preparation method, as well as a photovoltaic module. The self-assembled monolayer of this application has good flexibility and can cope with abrupt changes in interfacial stress through deformation, thereby further enhancing the interfacial connection strength and improving the photoelectric conversion efficiency of the perovskite solar cell.

[0018] In this perovskite solar cell, a self-assembled monolayer is disposed between the hole transport layer and the perovskite layer. This self-assembled monolayer is made of a self-assembled monomolecular material containing specific functional groups. Specifically, the organic oxyacid groups in the self-assembled monolayer are connected to the hole transport layer through coordination bonds and other interactions, while the methoxyphenyl group is bonded to the perovskite layer through hydrogen bonds and other interactions. Furthermore, flexible chains -(CH2) are attached to both the organic oxyacid groups and the methoxyphenyl group. n The flexible chain imparts deformable properties to the self-assembled monolayer. Therefore, when temperature changes cause deformation of the hole transport layer, the flexible chain attached to the organic oxyacid group deforms to accommodate this deformation. Similarly, when temperature changes cause deformation of the perovskite layer, the flexible chain attached to the methoxyphenyl group deforms to accommodate this deformation. In other words, by attaching flexible chains to both sides of the group, deformation of both the perovskite layer and the hole transport layer can be mitigated, effectively ensuring the interfacial bonding strength. Attached Figure Description

[0019] 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.

[0020] Figure 1 This is a schematic diagram of a stacked battery structure provided in an embodiment of this application (wherein, the first transport layer is a hole transport layer and the second transport layer is an electron transport layer). Figure 2 This is a schematic diagram of a single-junction battery provided in an embodiment of this application (wherein, the first transport layer is a hole transport layer and the second transport layer is an electron transport layer). Figure 3 These are scanning electron microscope images of the perovskite layer and electron transport layer of Embodiment 1 provided in this application; Figure 4 This is a scanning electron microscope image of the perovskite layer and electron transport layer of Comparative Example 2 provided in the embodiments of this application.

[0021] Icons: 1. Substrate; 11. Bottom battery; 12. Electron-hole recombination layer; 13. Glass substrate; 14. Transparent conductive oxide layer; 141. Isolation region; 2. First transport layer; 3. Self-assembled monolayer; 4. Perovskite layer; 5. Second transport layer; 6. Transparent conductive layer; 7. Electrode; 71. First electrode; 72. Second electrode; 8. Passivation layer; 9. Buffer layer; 10. Antireflection layer. Detailed Implementation

[0022] 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 skilled in the art without creative effort are within the scope of protection of this application.

[0023] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "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.

[0024] 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.

[0025] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0026] The technical solutions provided in this application will be further described below with reference to the embodiments and accompanying drawings.

[0027] In perovskite solar cells, both the heat treatment during fabrication and the changes caused by environmental temperature fluctuations (such as high or low temperatures) during use will cause varying degrees of deformation in the perovskite layer and hole transport layer due to differences in their expansion coefficients, resulting in expansion or contraction. This deformation causes abrupt changes in interfacial stress, weakens the interfacial bonding force, exacerbates carrier recombination losses at the interface, and restricts the improvement of photoelectric conversion efficiency of perovskite solar cells.

[0028] Based on the above problems, this application provides a perovskite solar cell and its preparation method, as well as a photovoltaic module. The self-assembled monolayer in the perovskite solar cell has elastic properties and can effectively cope with sudden changes in interface stress. This application discloses a perovskite solar cell, which includes a hole transport layer, a perovskite layer, and a self-assembled monolayer located between the hole transport layer and the perovskite layer. The material in a self-assembled monolayer includes a self-assembled monomolecule material, whose functional groups include an organic oxyacid group and a methoxyphenyl group, wherein the methoxyphenyl group is attached with a -(CH2) group. n -, an organic oxyacid group is attached with -(CH2). n - where n is a positive integer greater than or equal to 2.

[0029] Among them, self-assembled monomolecular materials refer to functional molecular materials that can spontaneously form monomolecular thin films at the interface through spontaneous and ordered intermolecular interactions. Preferably, the self-assembled monomolecular material is 2-(9H-carbazole-9-)phospho-9-ethyl-4-methoxybenzene, which has a π-π conjugated structure and electron-rich properties. These properties help to improve hole transport capabilities and reduce hole recombination losses. The structural formula of this substance is as follows: .

[0030] Optionally, the synthetic reaction formula for 2-(9H-carbazole-9-)phospho-9-ethyl-4-methoxybenzene is as follows:

[0031] The reagents and reaction conditions in the above synthetic reaction formula include: Ⅰ: Mix with dibromoalkane, then add tetrabutylammonium bromide and an aqueous solution of inorganic base, and stir at 70°C for 12 hours; II: Reaction with bis(pinacolyl)diboron, [1,1′-bis(diphenylphosphine)ferrocene]palladium dichloride (Pd(dppf)Cl2), trimethoprim (KOAc), and toluene at 110°C for 20 hours; III: Mix with dibromoalkane, then add tetrabutylammonium bromide and an aqueous solution of inorganic base, and stir at 70°C for 12 hours; IV: React with palladium acetate (Pd(OAc)2), 1,1′-ferrocene di-bis(diphenylphosphine) (DPPF), trimethoprim (KOAc), and 1,4-dioxane under reflux for 16 hours.

[0032] V: React with 1-bromo-4-iodobenzene, tetra-triphenylphosphine palladium (Pd(PPh3)4), sodium carbonate (Na2CO3), tetrahydrofuran (THF), and water under reflux for 8 hours.

[0033] VI: Trimethylbromosilane (TMSBr) and dichloromethane (CH2Cl2) were reacted at 25°C for 12 hours.

[0034] VII: Heat with sodium methoxide (NaOCH3) in methanol and react at 65°C for 6 hours.

[0035] Organic oxyacid groups refer to oxyacids attached to organic functional groups, including carboxylic acid groups and / or phosphonic acid groups.

[0036] In this perovskite solar cell, a self-assembled monolayer is disposed between the hole transport layer and the perovskite layer. This self-assembled monolayer is made of a self-assembled monomolecule material containing specific functional groups. Since the hole transport layer and the perovskite layer are made of different materials, the two layers will deform to different degrees when the temperature changes. Therefore, the self-assembled monomolecule material of this application has a flexible chain -(CH2) attached to the methoxyphenyl group connected to the perovskite layer. n Therefore, when temperature changes cause the perovskite layer to expand or contract, the flexible chain can stretch or contract to adapt to the deformation of the perovskite layer; and the self-assembled monomolecule material of this application has a flexible chain -(CH2) attached to the organic oxyacid group connected to the hole transport layer. n Therefore, when temperature changes cause the hole transport layer to expand or contract, the flexible chain can stretch or contract to adapt to the deformation of the hole transport layer. That is, the self-assembled monolayer and the hole transport layer and perovskite layer are respectively flexible in connection, so that the self-assembled monolayer has deformation characteristics and can effectively cope with the sudden change of interface stress, thereby further improving the interface connection strength between the self-assembled monolayer and the hole transport layer and perovskite layer.

[0037] In summary, the methoxyphenyl and organic oxyacid groups in the self-assembled monolayer of this application achieve connections with the perovskite layer and the hole transport layer, respectively, while -(CH2) n The presence of - makes the connection exhibit elastic properties, thus effectively coping with sudden changes in interface stress.

[0038] In this structure, the hole transport layer is an inorganic layer, while the perovskite layer is an organic layer. The significant difference in their coefficients of thermal expansion leads to substantial deformation under temperature changes, resulting in a sharp decrease in interfacial bonding strength. Therefore, by incorporating a self-assembled monolayer with elastic properties between the two layers, the interfacial bonding strength can be more effectively ensured. Specifically, the hole transport layer can be made of at least one of nickel oxide, molybdenum oxide, and vanadium oxide, while the perovskite layer can be made of at least one of formamidine iodide, formamidine bromide, methylamine bromide, and methylamine iodide.

[0039] When the hole transport layer is a nickel oxide layer formed by nickel oxide, the nickel oxide layer has a high carrier transport rate and a high matching degree with the perovskite layer, which helps to reduce carrier recombination loss and thus improve the photoelectric conversion efficiency of the perovskite solar cell to a greater extent.

[0040] Furthermore, n is 2 to 6. When n is within the above range, the length and molecular weight of the flexible chain of the self-assembled monolayer are suitable, resulting in lower intermolecular aggregation and better ensuring the compactness of the prepared film layer. Moreover, the above range further optimizes its elastic characteristics, enabling the self-assembled monolayer to more effectively cope with abrupt changes in interfacial stress. For example, n is 2, 3, 4, 5, or 6.

[0041] Furthermore, the relative molecular mass of the self-assembled monomolecule material is 400-600. Controlling the relative molecular mass of the self-assembled monomolecule material within this range helps to reduce the degree of molecular aggregation, thereby further improving the compactness of the film. Examples include molecular weights of 400, 450, 499, 550, or 600.

[0042] Furthermore, the ratio of the thickness of the hole transport layer, the thickness of the self-assembled monolayer, and the thickness of the perovskite layer is (5:1:200) to (5:1:150). When the thickness ratio of the hole transport layer, the self-assembled monolayer, and the perovskite layer is within the above range, it helps to ensure the elastic characteristics of the self-assembled monolayer, thereby enabling it to more effectively cope with abrupt changes in interfacial stress and ensuring the interfacial connection effect to a greater extent. For example, the thickness ratio is 5:1:150, 5:1:160, 5:1:170, 5:1:180, or 5:1:200, etc.

[0043] Furthermore, the thickness of the hole transport layer is 15 nm to 30 nm. When the thickness of the hole transport layer is within this range, it can effectively reduce the stress accumulation caused by temperature changes while ensuring the transport capacity of the hole transport layer for charge carriers, thereby significantly improving the photoelectric conversion efficiency of the perovskite solar cell. For example, the thickness is 15 nm, 17 nm, 19 nm, 21 nm, 25 nm, or 30 nm.

[0044] Furthermore, the thickness of the perovskite layer is 600 nm to 900 nm. When the thickness of the perovskite layer is within this range, it can effectively reduce the stress accumulation caused by temperature changes, while ensuring the light absorption effect of the perovskite layer and reducing the recombination loss of charge carriers in the perovskite layer, thereby significantly improving the photoelectric conversion efficiency of the perovskite solar cell. Examples include thicknesses of 600 nm, 660 nm, 720 nm, 790 nm, 850 nm, or 900 nm.

[0045] Furthermore, the thickness of the self-assembled monolayer is 3 nm to 6 nm; when the thickness of the self-assembled monolayer is within this range, it can more effectively cope with abrupt changes in interfacial stress, thereby improving the interfacial bonding force to a greater extent. For example, the thickness is 3 nm, 3.6 nm, 4.2 nm, 5 nm, 5.5 nm, or 6 nm, etc.

[0046] In one optional implementation, the solar cell in this application embodiment can be a tandem cell. For example... Figure 1 As shown below, the tandem battery will be further introduced.

[0047] The perovskite solar cell includes a substrate 1, which includes a bottom cell 11 and an electron-hole recombination layer 12 disposed on the bottom cell 11. The perovskite solar cell also includes a first transport layer 2, a perovskite layer 4, a second transport layer 5, and a transparent conductive layer 6 sequentially disposed on the electron-hole recombination layer 12. The perovskite solar cell also includes electrodes 7, which include a first electrode 71 and a second electrode 72. The first electrode 71 is in ohmic contact with the transparent conductive layer 6, and the second electrode 72 is in ohmic contact with the bottom cell 11. One of the first transport layer 2 and the second transport layer 5 is an electron transport layer and the other is a hole transport layer. One of the first electrode 71 and the second electrode 72 is a positive electrode and the other is a negative electrode.

[0048] When the first transport layer 2 is a hole transport layer and the second transport layer 5 is an electron transport layer, the self-assembled monolayer 3 is disposed at the lower interface of the perovskite layer 4. At this time, during the preparation of the perovskite layer 4, the annealing of the perovskite layer 4 will cause deformation of the hole transport layer and the perovskite layer 4. However, by setting the self-assembled monolayer 3 with elastic properties, the deformation problem caused by the annealing of the perovskite layer 4 can be effectively alleviated.

[0049] Furthermore, the electron-hole recombination layer 12 is made of at least one of indium zinc oxide and indium tin oxide. The thickness of the electron transport layer is 15 nm to 20 nm. The transparent conductive layer 6 is made of at least one of indium zinc oxide, indium tin oxide, and indium tin oxide, and the thickness of the transparent conductive layer 6 is 80 nm to 120 nm. The first electrode 71 and / or the second electrode 72 are made of at least one of silver, gold, copper, and aluminum, the thickness of the first electrode 71 is 150 nm to 300 nm, and the thickness of the second electrode 72 is 100 nm to 120 nm.

[0050] Furthermore, the perovskite solar cell also includes a passivation layer 8 disposed between the perovskite layer 4 and the electron transport layer. The material of the passivation layer 8 includes lithium fluoride. The passivation layer 8 can passivate the interface defects of the perovskite layer 4, improve the compatibility between the perovskite layer 4 and the electron transport layer, reduce interface defects, reduce interface recombination, thereby improving the extraction of charge carriers by the electron transport layer and improving the carrier migration capability.

[0051] In addition, the perovskite solar cell also includes a buffer layer 9 disposed between the second transport layer 5 and the transparent conductive layer 6. The buffer layer 9 is made of tin dioxide and has a thickness of 20 nm to 30 nm. The buffer layer 9 acts as a barrier, preventing damage to the second transport layer 5 and the perovskite layer 4 during the fabrication of the transparent conductive layer 6, thereby helping to improve the performance of the perovskite solar cell.

[0052] In addition, the perovskite solar cell also includes an anti-reflection layer 10 disposed on the transparent conductive layer 6. The anti-reflection layer 10 is made of at least one of magnesium fluoride and lithium fluoride, and has a thickness of 100 nm to 120 nm. By setting the anti-reflection layer 10 and controlling its thickness, the utilization rate of sunlight can be effectively improved, thereby improving the performance of the perovskite solar cell.

[0053] In another alternative implementation, the perovskite solar cell can be a single-junction cell. For example... Figure 2 As shown, the perovskite solar cell will be further described below.

[0054] The perovskite layer includes a substrate 1, which includes a glass substrate 13 and a transparent conductive oxide layer 14. The transparent conductive oxide layer 14 is disposed on the surface of the glass substrate 13. The perovskite solar cell also includes a first transport layer 2, which is disposed on a portion of the transparent conductive oxide layer 14 facing away from the glass substrate 13. A perovskite layer 4 is disposed on the side of the first transport layer 2 facing away from the glass substrate 13. The solar cell also includes a second transport layer 5 disposed on the side of the perovskite layer 4 facing away from the first transport layer 2. The perovskite solar cell also includes an electrode 7. Electrode 7 includes a first electrode 71 and a second electrode 72. The first electrode 71 is in ohmic contact with the second transport layer 5. The second electrode 72 is disposed on a portion of the transparent conductive oxide layer 14 facing away from the glass substrate 13. The second electrode 72 is in ohmic contact with the transparent conductive oxide layer 14, and the second electrode 72 and the first transport layer 2 are separated by an isolation region 141. In the first transport layer 2 and the second transport layer 5, one is an electron transport layer and the other is a hole transport layer. One of the first electrode 71 and the second electrode 72 is a positive electrode and the other is a negative electrode.

[0055] This application discloses a method for fabricating a perovskite solar cell, the method comprising the following steps: A self-assembled monolayer is prepared between a hole transport layer and a perovskite layer; wherein the material in the self-assembled monolayer includes a self-assembled monomolecule material, the functional groups of which include an organic oxyacid group and a methoxyphenyl group, wherein the methoxyphenyl group is attached with -(CH2). n -, an organic oxyacid group is attached with -(CH2). n- where n is a positive integer greater than or equal to 2; Post-processing yields the aforementioned perovskite solar cells.

[0056] Furthermore, the preparation method includes the following steps: A self-assembled monomolecular material was coated on a hole transport layer and then subjected to a first annealing process to obtain a self-assembled monomolecular layer. Perovskite layers were prepared on self-assembled monolayers.

[0057] Furthermore, the mass concentration of the self-assembled monolayer is 0.8 mg / mL to 1.2 mg / mL. By controlling the mass concentration within this range, the elasticity of the prepared self-assembled monolayer can be effectively ensured, thereby significantly improving the interfacial bonding strength. For example, the mass concentration of the self-assembled monolayer is 0.8 mg / mL, 0.9 mg / mL, 1.0 mg / mL, 1.1 mg / mL, or 1.2 mg / mL, etc.

[0058] In the first annealing step, the annealing temperature is 90℃~110℃, and the time is 5 min~15 min; by controlling the annealing parameters, the high quality of the prepared film layer is further ensured. For example, the temperature is 90℃, 95℃, 100℃, 105℃, or 110℃, and the time is 5 min, 7 min, 9 min, 11 min, or 15 min, etc.

[0059] The coating rotation speed is 3000 rpm to 4500 rpm. Controlling the coating rotation speed within this range helps to promote contact between the self-assembled monomolecule material and the perovskite layer and hole transport layer, thereby contributing to a higher degree of interfacial bonding strength. Examples include rotation speeds of 3000 rpm, 3400 rpm, 3800 rpm, 4200 rpm, or 4500 rpm.

[0060] In one alternative embodiment, a perovskite layer is prepared using a one-step method, in which a lead halide solution and a cation solution are mixed and then spin-coated onto a self-assembled monolayer.

[0061] In another alternative embodiment, a two-step method is used to prepare the perovskite layer. The steps for preparing the perovskite layer on a self-assembled monolayer include: Prepare lead halide framework layers on self-assembled monolayers; A cationic solution is coated onto a lead halide framework layer, followed by a second annealing process to obtain a perovskite layer.

[0062] Among them, the two-step method for preparing the perovskite layer is more conducive to improving the shape retention of the perovskite layer. Therefore, when a textured structure is set on the substrate, the textured structure of the perovskite layer prepared at this time has high shape retention, which is more conducive to improving the absorption and utilization rate of sunlight by utilizing the anti-reflection effect of the textured structure.

[0063] Furthermore, in the second annealing step, the annealing temperature is 120℃~140℃, and the annealing time is 20min~40min. By controlling the annealing parameters within the above range in the second annealing step, the crystallinity quality of the perovskite layer can be effectively ensured, while excessive expansion of the perovskite layer and hole transport layer can be effectively avoided, thereby significantly improving the perovskite layer. For example, the temperature can be 120℃, 125℃, 130℃, 135℃, or 140℃, and the time can be 20min, 25min, 30min, 35min, or 40min.

[0064] This application discloses a photovoltaic module, which includes: the perovskite solar cell described above, or includes: a perovskite solar cell prepared by the preparation method described above.

[0065] The technical solution of this application will be further explained below with reference to more specific embodiments and experimental test results.

[0066] Example 1: This application provides a perovskite solar cell, which is a tandem cell. Taking an HJT crystalline silicon bottom cell as an example, the fabrication method of this tandem cell includes the following steps: A crystalline silicon bottom cell with HJT is provided, and a 20 nm thick indium tin oxide electron-hole composite layer is prepared by magnetron sputtering on the light-receiving surface of the bottom cell.

[0067] A 20 nm thick nickel oxide hole transport layer was deposited on the electron-hole composite layer using physical vapor deposition.

[0068] Preparation of self-assembled monolayers on nickel oxide hole transport layers: A self-assembled monomolecule material was coated on the hole transport layer. The mass concentration of the self-assembled monomolecule material was 1.0 mg / mL, the rotation speed was 3500 rpm, and the self-assembled monomolecule material was 2-(9H-carbazole-9-)phospho-9-ethyl-4-methoxyphenyl. A self-assembled monolayer with a thickness of 4 nm was obtained by annealing at 100 °C for 10 minutes.

[0069] Preparation of perovskite layers on self-assembled monolayers: A 350 nm thick lead framework layer was fabricated by dual-source co-evaporation on a self-assembled monolayer. A cationic solution was obtained by mixing 0.4 mol / L FAI, 0.1 mol / L FABr, 0.1 mol / L MABr, and 0.15 mol / L MACl and dissolving them in ethanol. The solution was then coated onto a lead framework layer using a spin-coating method at a speed of 4500 rpm for 30 s. The layer was then annealed at 130 °C for 30 min to obtain a perovskite layer with a thickness of 720 nm.

[0070] A 1 nm thick lithium fluoride passivation layer was deposited on the perovskite layer at a deposition rate of 0.1 Å / s.

[0071] A 15 nm thick C60 electron transport layer was deposited on the lithium fluoride passivation layer at a deposition rate of 0.2 Å / s.

[0072] A 20 nm thick tin dioxide buffer layer was prepared on the electron transport layer using atomic layer deposition.

[0073] A transparent conductive layer of indium zinc oxide with a thickness of approximately 90 nm was prepared on the buffer layer by magnetron sputtering.

[0074] A 200 nm thick silver first electrode was prepared by vacuum evaporation on a transparent conductive layer, and a 100 nm thick silver second electrode was prepared by vacuum evaporation on the backlight surface of the bottom battery. The first electrode is the positive electrode and the second electrode is the negative electrode.

[0075] A lithium fluoride antireflection layer with a thickness of approximately 110 nm was deposited on the first electrode.

[0076] Example 2: The only difference between this embodiment and Embodiment 1 is that the ratio of the thickness of the hole transport layer, the thickness of the self-assembled monolayer, and the thickness of the perovskite layer in this embodiment is 5:1:200.

[0077] Example 3: The only difference between this embodiment and Embodiment 1 is that the ratio of the thickness of the hole transport layer, the thickness of the self-assembled monolayer, and the thickness of the perovskite layer in this embodiment is 5:1:150.

[0078] Example 4: The only difference between this embodiment and Embodiment 1 is that the ratio of the thickness of the hole transport layer, the thickness of the self-assembled monolayer, and the thickness of the perovskite layer in this embodiment is 5:1:240.

[0079] Example 5: The only difference between this embodiment and Embodiment 1 is that n is 6.

[0080] Example 6: The only difference between this embodiment and Embodiment 1 is that n is 7.

[0081] Comparative Example 1: The only difference between this comparative example and Example 1 is that no self-assembled monolayer is provided between the hole transport layer and the perovskite layer in this comparative example.

[0082] Comparative Example 2: The only difference between this comparative example and Example 1 is that the self-assembled monomolecule material in this comparative example is 2PACZ.

[0083] Comparative Example 3: The only difference between this comparative example and Example 1 is that the structural formula of the self-assembled monomolecule material in this comparative example is: .

[0084] Structural Test 1: Figure 3 This is a scanning electron microscope image of the interface between the perovskite layer and the hole transport layer in Example 1. Figure 4 This is a schematic diagram of the interface between the perovskite layer and the hole transport layer in Comparative Example 2. Because the thickness of the self-assembled monolayer is too low, it is difficult to visualize the self-assembled monolayer using a scanning electron microscope. Analysis of these two figures shows that... Figure 3 The higher interfacial connectivity between the perovskite layer and the hole transport layer indicates that setting a flexible self-assembled monolayer between the perovskite layer and the hole transport layer can effectively improve the interfacial connectivity and further enhance the photoelectric conversion efficiency of perovskite solar cells.

[0085] Performance testing: The perovskite solar cells prepared in Examples 1 to 6 and Comparative Examples 1 to 2 were subjected to the following related tests: This application describes the performance testing of a perovskite solar cell using a Halm testing and sorting system. The Halm system simulates sunlight and is equipped with electronic loads, data acquisition and computing devices to test the electrical performance of photovoltaic devices (including solar cells), such as Eta, Voc, Jsc, and FF. These parameters reflect the performance of the solar cell. The silicon wafer used for the controlled test is 1.07 cm². 2 The calibrated light intensity was 1000±50 W / m². The experimental results are as follows, where Voc represents the open-circuit voltage, Jsc represents the short-circuit current density, FF represents the fill factor, and Eta represents the photoelectric conversion efficiency. The experimental results are shown in Table 1, which presents the performance test results of the perovskite solar cell.

[0086] Table 1 Performance test results of solar cells

[0087] Comparing the data from Example 1 with Comparative Examples 1 to 3, it can be seen that the photoelectric conversion efficiency of Example 1 is superior to that of Comparative Examples 1 to 3. This demonstrates that a self-assembled monolayer is disposed between the hole transport layer and the perovskite layer, and that -(CH2) groups are attached to the methoxyphenyl group and the organic oxyacid group in this self-assembled monolayer. n Therefore, this self-assembled monolayer has good flexibility and can effectively cope with sudden changes in interfacial stress through deformation, thereby effectively improving the photoelectric conversion efficiency of perovskite solar cells.

[0088] Comparing the data from Examples 1 to 4, it can be seen that the photoelectric conversion efficiency of Examples 1 to 3 is better than that of Example 4. This indicates that the ratio of the thickness of the hole transport layer, the self-assembled monolayer, and the perovskite layer in Examples 1 to 3 is more suitable. A more suitable ratio helps the self-assembled monolayer to exert its elastic characteristics, thereby improving the photoelectric conversion efficiency of the solar cell to a greater extent.

[0089] Comparing the data from Examples 1, 5, and 6, it is evident that the photoelectric conversion efficiency of Examples 1 and 5 is superior to that of Example 6. This indicates that the n-values ​​in Examples 1 and 5 are more suitable, resulting in appropriate lengths and molecular weights for the flexible chains of the self-assembled monolayer, leading to lower intermolecular aggregation and better ensuring the compactness of the prepared film. Furthermore, the aforementioned range further optimizes its elastic characteristics, enabling the self-assembled monolayer to more effectively cope with abrupt changes in interfacial stress.

[0090] The perovskite solar cells, their preparation methods, and photovoltaic modules disclosed in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the perovskite solar cells, their preparation methods, and photovoltaic modules. 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 solar cell, characterized in that, The perovskite solar cell includes a hole transport layer, a perovskite layer, and a self-assembled monolayer located between the hole transport layer and the perovskite layer. The material in the self-assembled monolayer includes a self-assembled monomolecule material, the functional groups of which include an organic oxyacid group and a methoxyphenyl group, wherein -(CH2) is attached to the methoxyphenyl group and the organic oxyacid group, respectively. n - where n is a positive integer greater than or equal to 2.

2. The perovskite solar cell according to claim 1, characterized in that, The value of n is 2 to 6.

3. The perovskite solar cell according to claim 1, characterized in that, The ratio of the thickness of the hole transport layer, the thickness of the self-assembled monolayer, and the thickness of the perovskite layer is (5:1:200) to (5:1:150).

4. The perovskite solar cell according to claim 3, characterized in that, The thickness of the hole transport layer is 15 nm to 30 nm; and / or, The thickness of the perovskite layer is 600 nm to 900 nm; and / or, The thickness of the self-assembled monolayer is 3 nm to 6 nm.

5. The perovskite solar cell according to claim 1, characterized in that, The organic oxyacid groups include carboxylic acid groups and / or phosphonic acid groups.

6. The perovskite solar cell according to claim 1, characterized in that, The self-assembled monomolecule material is 2-(9H-carbazole-9-)phospho-9-ethyl-4-methoxyphenyl; and / or, The hole transport layer is at least one of a nickel oxide layer, a molybdenum oxide layer, and a vanadium oxide layer; and / or, The relative molecular mass of the self-assembled monomolecule material is 400~600.

7. The perovskite solar cell according to any one of claims 1 to 6, characterized in that, The perovskite solar cell is a tandem cell. The perovskite solar cell includes a substrate, the substrate including a bottom cell and an electron-hole recombination layer disposed on the bottom cell. The perovskite solar cell further includes a first transport layer disposed on the side of the electron-hole recombination layer opposite to the bottom cell, the perovskite layer being disposed on the side of the first transport layer opposite to the electron-hole recombination layer. The perovskite solar cell also includes a second transport layer and a transparent conductive layer sequentially disposed on the side of the perovskite layer opposite to the first transport layer. The perovskite solar cell further includes electrodes, the electrodes including a first electrode and a second electrode. The first electrode is in ohmic contact with the transparent conductive layer, and the second electrode is in ohmic contact with the bottom cell. 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. Alternatively, the perovskite solar cell is a single-junction cell. The perovskite solar cell includes a substrate, which comprises a glass substrate and a transparent conductive oxide layer. The transparent conductive oxide layer is disposed on the surface of the glass substrate. The perovskite solar cell further includes a first transport layer, which is disposed on a portion of the transparent conductive oxide layer facing away from the glass substrate. The perovskite layer is disposed on the side of the first transport layer facing away from the transparent conductive oxide layer. The perovskite solar cell further includes a second transport layer disposed on the side of the perovskite layer facing away from the first transport layer. The perovskite solar cell also includes electrodes, which include a first electrode and a second electrode. The first electrode is in ohmic contact with the second transport layer. The second electrode is disposed on a portion of the transparent conductive oxide layer facing away from the glass substrate and is in ohmic contact with the transparent conductive oxide layer. The second electrode and the first transport layer are separated by an isolation region. 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.

8. A method for preparing a perovskite solar cell, characterized in that, The preparation method includes the following steps: A self-assembled monolayer is prepared between a hole transport layer and a perovskite layer; wherein the material of the self-assembled monolayer includes a self-assembled monomolecule material, the functional groups of which include an organic oxyacid group and a methoxyphenyl group, wherein the methoxyphenyl group is attached with a -(CH2) group. n - The organic oxyacid group is attached with -(CH2). n - where n is a positive integer greater than or equal to 2; Post-processing yields the perovskite solar cell as described in any one of claims 1 to 7.

9. The preparation method according to claim 8, characterized in that, The preparation method includes the following steps: The self-assembled monomolecular material is coated on the hole transport layer and then subjected to a first annealing process to obtain the self-assembled monomolecular layer. The perovskite layer is prepared on the self-assembled monolayer.

10. The preparation method according to claim 9, characterized in that, The mass concentration of the self-assembled monomolecule material is 0.8 mg / mL to 1.2 mg / mL; and / or, In the first annealing step, the annealing temperature is 90℃~110℃, and the time is 5 min~15 min; and / or, The coating speed is 3000 rpm to 4500 rpm.

11. A photovoltaic module, characterized in that, The photovoltaic module includes: the perovskite solar cell according to any one of claims 1 to 7, or includes: the perovskite solar cell prepared by the preparation method according to any one of claims 8 to 10.

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