Hole transport layer, perovskite solar cell and preparation method thereof

Abstract

The embodiment of the invention relates to the technical field of solar cells, in particular to a hole transport layer, a perovskite solar cell and a preparation method thereof. The hole transport layer comprises a NiOx layer and a self-assembly monomolecular layer, wherein the self-assembly monomolecular layer comprises a self-assembly monomolecular material and an additive; the structural formula of the additive is HO (CH2) nCOOH; wherein n is a positive integer greater than or equal to 1; the perovskite photoactive layer is prepared by a solution method. According to the embodiment of the invention, the additive is adopted to improve the problem of poor wettability of the self-assembled monomolecular layer to the perovskite precursor solution.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a hole transport layer, a perovskite solar cell and a preparation method thereof. Background Art

[0002] NiO x NiO is a P-type semiconductor that is commonly used as the hole transport layer (HTL) in inverted and tandem perovskite solar cells (PSCs) due to its cost-effectiveness, stability, and scalability. x Inverted perovskite solar cells have achieved high conversion efficiency (PCE), and there is still room for improvement. x The elimination of surface-uncoordinated metal ion defects at the interface of the Mg / perovskite photoactive layer contributes to this enhanced potential.

[0003] Based on this, self-assembled monolayers (SAMs) can be used to passivate NiO x / perovskite photoactive layer interface defects, but with it comes the poor wettability of the introduced self-assembled monolayer to the perovskite precursor solution.

[0004] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the invention

[0005] The embodiments of the present application provide a hole transport layer, a perovskite solar cell and a method for preparing the same to solve or alleviate one or more of the technical problems raised above.

[0006] The first aspect of the embodiment of the present application provides a hole transport layer, characterized in that the hole transport layer comprises NiO x A layer and a self-assembled monolayer, wherein the self-assembled monolayer comprises a self-assembled monomolecular material and an additive; The structural formula of the additive is HO(CH2) n COOH; Wherein, n is a positive integer greater than or equal to 1.

[0007] In the first aspect of the embodiment of the present application, additives are used to improve the poor wettability of the hole transport layer to the perovskite precursor solution. Both the hydroxyl and carboxyl groups in the additive can effectively improve the wettability of the self-assembled monomolecule. The carboxyl group, as a polar group, can react with the polar end in the solvent of the perovskite precursor solution to form a hydrogen bond, so that the self-assembled monolayer exhibits hydrophilicity, which is convenient for the perovskite precursor solution to spread on the self-assembled monolayer, and then it is convenient to obtain a high-quality perovskite photoactive layer, which is beneficial to the improvement of the performance of the perovskite battery; in addition, the carboxyl group in the additive can coordinate with the uncoordinated metal ions in the perovskite photoactive layer, and at the same time play a role in suppressing the interface defects of the self-assembled monolayer / perovskite photoactive layer.

[0008] In a second aspect of the present application, a perovskite solar cell is provided, wherein the perovskite solar cell comprises a hole transport layer and a perovskite photoactive layer which are stacked; wherein the hole transport layer comprises the hole transport layer described in the first aspect.

[0009] In a second aspect of the present application, the hole transport layer of the first aspect can form a high-quality perovskite photoactive layer, while the defects between the hole transport layer and the perovskite photoactive layer are reduced, and the performance of the perovskite cell is improved.

[0010] A third aspect of the present application provides a method for preparing a perovskite solar cell, the method comprising the following operations: A transparent conductive substrate is provided, wherein NiO is stacked on the transparent conductive substrate x layer; The first solution method is used to prepare the NiO x Prepare a self-assembled monolayer on the layer; preparing a perovskite photoactive layer on the self-assembled monolayer by a second solution method; Wherein, when preparing the self-assembled monolayer, the precursor solution used includes the self-assembled monolayer material and additives; The structural formula of the additive is HO(CH2) n COOH; Wherein, n is a positive integer greater than or equal to 1.

[0011] According to the second aspect of the embodiment of the present application, the preparation process is simple, and the coverage and uniformity of the perovskite photoactive layer are significantly improved, which is conducive to commercialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0013] Figure 1 Is a SEM image provided in Example 1; Figure 2 It is the SEM picture provided by Comparative Example 1; Figure 3 It is a schematic diagram of the structure of the perovskite battery provided in the embodiment of the present application.

[0014] Among them, 1-transparent conductive substrate; 2-hole transport layer; 3-perovskite photoactive layer; 4-electron transport layer; 5-hole blocking layer; 6-counter electrode. DETAILED DESCRIPTION

[0015] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0016] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. When the second element, component, region, layer or part is discussed, it does not indicate that the present application necessarily has the first element, component, region, layer or part.

[0017] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0018] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0019] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0020] To solve the NiO x In order to solve the interface problem of NiO / perovskite layer, various methods have been used in related technologies to improve the interface problem of the two. For example, inorganic salts, self-assembled monolayers (SAMs), organic molecules and 2D materials are used to modify and passivate the interface. Li et al. used NiO processed by SAMs to xThe nanocrystals successfully improved the interface and effectively bridged the perovskite photoactive layer. This approach creatively adopted hole-selective contacts, mitigated interface recombination, and promoted hole extraction. The results showed that a remarkable efficiency of 24.7% (certified as 24.4%) was achieved in flexible all-perovskite tandem solar cells. In addition, Huang et al. used (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz) to reduce NiO x / formamidiniumtriiodiide (FAPbI3) junctions, and by reducing these defects and improving carrier transport, a PCE of 23.56% was achieved in inverted FAPbI3-based PSCs. Researchers continue to improve the design of SAMs, resulting in significant progress in the development of high-performance photovoltaic devices. SAMs composed of a carbazole core and phosphonic acid, such as (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACz) and Me-4PACz, are particularly popular due to their maturity in industrial applications. However, despite the widespread use of the above SAMs materials, there are still some issues that need to be addressed, such as wettability.

[0021] Based on this, the inventors modified the NiO-based x The buried interface of PSCs is used to solve the problem of poor wettability of SAMs to perovskite precursor solution.

[0022] The embodiments of the present application provide a hole transport layer, a perovskite solar cell and a method for preparing the same, as described below.

[0023] Hereinafter, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. It should be noted that these exemplary embodiments can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0024] In a first aspect, an embodiment of the present application provides a hole transport layer, wherein the hole transport layer comprises NiO x A layer and a self-assembled monolayer, wherein the self-assembled monolayer comprises a self-assembled monomolecular material and an additive; The structural formula of the additive is HO(CH2) n COOH; Wherein, n is a positive integer greater than or equal to 1.

[0025] In the first aspect of the embodiment of the present application, additives are used to improve the problem of poor wettability of the hole transport layer to the perovskite precursor solution. Both the hydroxyl and carboxyl groups in the additive can effectively improve the wettability of the self-assembled monomolecule. As a polar group, the carboxyl group can react with the polar end in the solvent of the perovskite precursor solution to form a hydrogen bond, so that the self-assembled monolayer exhibits hydrophilicity, which is convenient for the perovskite precursor solution to spread on the self-assembled monolayer, and then it is convenient to obtain a high-quality perovskite photoactive layer, which is beneficial to the improvement of the performance of the perovskite battery; in addition, the carboxyl group in the additive can coordinate with the uncoordinated metal ions in the perovskite photoactive layer, which plays a role in suppressing the interface defects of the self-assembled monolayer / perovskite photoactive layer.

[0026] It is worth noting that in the actual preparation process of nickel oxide, oxygen is often excessive, and NiOOH and Ni2O3 will also exist in nickel oxide, making nickel oxide in a non-stoichiometric state (denoted as NiO x ), and generate a certain number of Ni vacancies, which in turn generate holes, so NiO x It is a P-type semiconductor.

[0027] In some embodiments, in the hole transport layer, n is a positive integer of 1 to 6, such as 1, 2, 3, 4, 5, or 6.

[0028] Preferably, n is 1, and the structural formula of the additive is HOCH2COOH, that is, the additive is glycolic acid.

[0029] In some embodiments, in the hole transport layer, the mass ratio of the self-assembled monolayer material and the additive in the self-assembled monolayer is 1:(0.2-2), for example, 1:0.2, 1:0.5, 1:1, 1:1.5, 1:2, etc. Thus, the self-assembled monolayer has the passivation of interface defects and improved wettability while not affecting its own performance as a hole transport layer.

[0030] Preferably, in the hole transport layer, the NiO x The thickness of the layer is 10nm to 20nm, for example, 10nm, 13nm, 16nm, 20nm, etc. The thickness of the hole transport layer is equal to NiO x The thickness of the layer is the sum of the thickness of the self-assembled monolayer, and the thickness of the self-assembled monolayer is about 1nm. Therefore, the thickness of the hole transport layer is 11nm to 21nm, which optimizes hole transport.

[0031] In some embodiments, in the hole transport layer, the self-assembled monomolecular material includes a monomolecular self-assembled material of phosphonic acid groups and / or a monomolecular self-assembled material of carboxylic acid groups.

[0032] Exemplarily, the single-molecule self-assembly material of the phosphonic acid group includes at least one of (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACZ), (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid (MeO-2PACZ), and (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACZ). The single-molecule self-assembly material of the carboxylic acid group may be 9H-carbazole-2-carboxylic acid.

[0033] The second aspect of the present application provides a perovskite solar cell, which comprises a stacked hole transport layer and a perovskite photoactive layer; wherein the hole transport layer comprises the hole transport layer described in the first aspect. Thus, a high-quality perovskite photoactive layer can be obtained and the interface defects between the perovskite photoactive layer and the hole transport layer can be reduced.

[0034] In some embodiments, participating Figure 3 The perovskite solar cell further comprises a transparent conductive substrate 1, an electron transport layer 4, a hole blocking layer 5 and a counter electrode 6; the transparent conductive substrate 1, the hole transport layer 2, the perovskite photoactive layer 3, the electron transport layer 4, the hole blocking layer 5 and the counter electrode 6 are stacked in sequence. As a result, the interface defects of the hole transport layer / perovskite photoactive layer are reduced, and the wettability of the self-assembled monolayer on the hole transport layer is improved, so that the distribution of the perovskite photoactive layer thereon is more uniform, so that the conversion efficiency and stability of the inverse perovskite solar cell are improved.

[0035] The present embodiment of the present application does not limit the material and thickness of the transparent conductive substrate 1, the electron transport layer 4, the hole blocking layer 5 and the counter electrode 6. Preferably, the perovskite solar cell satisfies at least one of the following conditions: (A) the chemical formula of the perovskite photoactive material in the perovskite photoactive layer 3 is: ABX3; wherein A is selected from FA + 、MA + , Cs + , Rb + At least one of; B is selected from Pb 2+ ; X is selected from Cl - Br ‐ ,I ‐ At least one of; Exemplarily, the perovskite photoactive material in the perovskite photoactive layer 3 may be FAPbI3, FAMAPbI3, FACsPbI3 or FAMACsPbI3, whereby the introduction of the additive can allow the carboxyl group to react with the uncoordinated Pb in the perovskite photoactive layer 3 2+(B) The thickness of the perovskite photoactive layer 3 is 400nm to 600nm, for example, 400nm, 450nm, 500nm, 600nm, etc.; (C) The electron transport layer includes C 60 、Fullerene derivatives(PCBM(C 70 )) at least one of; (D) the thickness of the electron transport layer 4 is 20nm to 40nm, for example, 20nm, 30nm, 40nm, etc.; (E) the material of the hole blocking layer 5 includes at least one of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and SnO2; (F) the thickness of the hole blocking layer 5 is 5nm to 10nm, for example, 5nm, 6nm, 8nm, 10nm; (G) the material of the counter electrode 6 includes at least one of Au, Ag, and Cu; (H) the thickness of the counter electrode 6 is 60nm to 80nm, for example, 60nm, 70nm, 80nm, etc. (I) The transparent conductive substrate 1 includes fluorine-doped SnO2 conductive glass (FTO glass), indium tin oxide conductive glass (ITO glass) or a flexible ITO conductive substrate. This is conducive to optimizing the comprehensive performance of the perovskite solar cell. The third aspect of the embodiment of the present application provides a method for preparing a perovskite solar cell.

[0036] In some embodiments, the method for preparing the perovskite solar cell may include the following operations: S1. Provide a transparent conductive substrate, on which NiO is stacked x layer; Optionally, the transparent conductive substrate may be FTO glass, ITO glass or a flexible ITO conductive substrate.

[0037] Alternatively, NiO can be prepared by magnetron sputtering. x Thus, a dense and uniform NiO x layer.

[0038] S2, using the first solution method in the NiO x Prepare a self-assembled monolayer on the layer; When preparing the self-assembled monolayer, the precursor solution used includes a self-assembled monolayer material and an additive; the structural formula of the additive is HO(CH2) n COOH. Therefore, the addition of additives is used to improve the wettability of the self-assembled monolayer to the perovskite precursor solution.

[0039] Optionally, in the precursor solution, the concentration of the self-assembled monomolecular material is 0.4 mg / ml to 1 mg / ml, for example, 0.4 mg / ml, 0.5 mg / ml, 0.8 mg / ml, 1 mg / ml, etc. The concentration of the additive is 0.2 mg / ml to 0.8 mg / ml, for example, 0.2 mg / ml, 0.3 mg / ml, 0.5 mg / ml, 0.6 mg / ml, 0.8 mg / ml, etc. Thus, a self-assembled monolayer with high coverage is formed.

[0040] Optionally, in the precursor solution, the solvent includes at least one of ethanol and isopropanol.

[0041] Furthermore, the solution method includes at least one of spin coating, dip coating and slit coating. Thus, the precursor solution is coated on the transparent conductive substrate by the solution method to form a self-assembled monolayer.

[0042] S3, preparing a perovskite photoactive layer on the self-assembled monolayer by a second solution method. Thus, due to the presence of the additive, the wettability of the self-assembled monolayer to the perovskite precursor solution is improved, so that the prepared perovskite photoactive layer is more uniform.

[0043] In some embodiments, the solute of the perovskite precursor solution may include at least one of FAMAPbI3, FACsPbI3, and FAMACsPbI3; the solvent may include at least one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), γ-butyrolactone (GBL), and N-methylpyrrolidone (NMP). Exemplarily, the solvent may be a mixed solvent of DMF and DMSO in a volume ratio of (3 to 5):1, a mixed solvent of GBL and NMP in a volume ratio of (3 to 5):1, and a mixed solvent of DMF and NMP in a volume ratio of (3 to 5):1.

[0044] In some embodiments, a perovskite photoactive layer can be prepared on a self-assembled monolayer by spin coating. Specifically, the rotation speed of the spin coating perovskite precursor solution can be 4000 rpm to 6000 rpm, for example, 4000 rpm, 5000 rpm, 6000 rpm, etc. After spin coating, annealing is performed at 100° C. to 150° C. for 15 min to 35 min. Thus, a well-crystallized perovskite photoactive layer can be obtained.

[0045] [Example 1] The specific preparation process is: Step 100: Cleaning the FTO glass surface; Step 101: placing the FTO glass in an ultrasonic cleaning device, and cleaning the FTO glass with deionized water and ethanol in steps, each cleaning step lasts for 20 minutes, and drying with nitrogen for use; Step 102: treating the ultrasonically cleaned FTO glass with ultraviolet ozone for 20 minutes; Step 200: Preparation of hole transport layer (HTL) Step 201: Magnetron sputtering of 15nm NiO on FTO glass x layer, and the sputtering method is radio frequency sputtering; Step 202: preparing a precursor solution, using ethanol as a solvent, Me-4PACZ as a self-assembled monomolecular material, and glycolic acid as an additive; in the prepared precursor solution, the concentration of Me-4PACZ is 0.6 mg / ml, and the concentration of glycolic acid is 0.4 mg / ml; Step 203: spin-coating the precursor solution on the FTO glass at a rotation speed of 3000 rpm, and then keeping it at 100° C. for 10 minutes to evaporate the ethanol, thereby obtaining a 16 nm hole transport layer; Step 300: Preparation of perovskite photoactive layer (PVK) Step 301: using DMF and NMP in a volume ratio of 4:1 as solvent and FAPbI3 as solute, a 1.2 mol / L FAPbI3 solution is prepared as a perovskite precursor; Step 302: Spin-coat the perovskite precursor onto the hole transport layer using a one-step spin coating method, with a spin coating speed of 5000 rpm and a spin coating time of 30 seconds; Step 303: 5 seconds before the end of the spin coating deposition, 300 μl of anisole was added dropwise to obtain a perovskite wet film; Step 304: annealing at 150° C. for 15 min to obtain a perovskite photoactive layer; Step 400: Preparation of electron transport layer (ETL) Step 401: Evaporate 30nm thick C on the perovskite photoactive layer at 0.5Å / s 60 layer, serving as an electron transport layer; Step 500: Preparation of hole blocking layer Step 501: In C 60 A 6 nm thick BCP layer was evaporated on the layer at 0.5 Å / s as a hole blocking layer.

[0046] Step 600: preparing a metal electrode; Step 601: The hole blocking layer is subjected to thermal evaporation to form a silver film, and a 70 nm silver electrode is evaporated.

[0047] [Example 2] The other steps are the same as those in Example 1, except that: Step 202: In the prepared precursor solution, the concentration of Me-4PACZ is 0.4 mg / ml, and the concentration of glycolic acid is 0.4 mg / ml.

[0048] [Example 3] The other steps are the same as those in Example 1, except that: Step 202: In the prepared precursor solution, the concentration of Me-4PACZ is 1 mg / ml, and the concentration of glycolic acid is 0.4 mg / ml.

[0049] [Example 4] Step 202: In the prepared precursor solution, the concentration of Me-4PACZ is 0.6 mg / ml, and the concentration of glycolic acid is 0.2 mg / ml.

[0050] [Example 5] Step 202: In the prepared precursor solution, the concentration of Me-4PACZ is 0.6 mg / ml, and the concentration of glycolic acid is 0.8 mg / ml.

[0051] [Example 6] Step 202: In the prepared precursor solution, the concentration of Me-4PACZ is 0.6 mg / ml, and the concentration of glycolic acid is 0.1 mg / ml.

[0052] [Example 7] Step 202: In the prepared precursor solution, the concentration of Me-4PACZ is 0.6 mg / ml, and the concentration of glycolic acid is 1 mg / ml.

[0053] [Comparative Example 1] Step 202: In the prepared precursor solution, the concentration of Me-4PACZ is 0.6 mg / ml, and no glycolic acid is added.

[0054]

Test example

[0055] 2. The variables of Examples 2 to 7 and Comparative Example 1 are shown in Table 1. At light intensity: 1000 W / m 2 (AM 1.5G spectrum), IV tests were performed on the perovskite cells of Examples 1 to 7 and Comparative Example 1 at a temperature of 25°C. The results are also shown in Table 1.

[0056] Table 1

[0057] Note: Jsc is short-circuit current; Voc is open-circuit voltage; FF is fill factor; PCE is conversion efficiency.

[0058] As can be seen from Table 1, the performance of Examples 1 to 7 is better than that of Comparative Example 1. This is because the addition of glycolic acid can improve the interface defects between the hole transport layer and the perovskite photoactive layer, and the distribution of the perovskite photoactive layer is more uniform due to the improvement of wettability. Furthermore, only the concentration of Me-4PACZ is changing in Examples 1 to 3, and the conversion efficiency of Examples 1 and 2 is better than that of Example 3, which shows that the preferred concentration range of Me-4PACZ is 0.4 mg / ml to 0.6 mg / ml. Only the concentration of glycolic acid changes in Examples 1, 4, 5, 6 and 7, and the conversion efficiency of Examples 1, 4 and 5 is higher than that of Examples 6 and 7. This is because the glycolic acid in Example 6 is too low to achieve the effect of improving wettability, while the glycolic acid in Example 7 is too high.

[0059] It should be noted that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0060] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0061] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0062] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A hole transport layer, characterized in that: The hole transport layer includes NiO x A layer and a self-assembled monolayer, wherein the self-assembled monolayer comprises a self-assembled monomolecular material and an additive; The structural formula of the additive is HO(CH2) n COOH; Wherein, n is a positive integer greater than or equal to 1.

2. The hole transport layer according to claim 1, characterized in that n is a positive integer from 1 to 6.

3. The hole transport layer according to claim 1, characterized in that n is 1.

4. The hole transport layer according to claim 1, characterized in that In the self-assembled monolayer, the mass ratio of the self-assembled monolayer material to the additive is 1:(0.2-2).

5. The hole transport layer according to claim 1, characterized in that In the hole transport layer, the NiO x The thickness of the layer is 10 nm to 20 nm.

6. The hole transport layer according to claim 1, characterized in that The self-assembled monomolecular material includes a monomolecular self-assembled material of a phosphonic acid group and / or a monomolecular self-assembled material of a carboxylic acid group.

7. A perovskite solar cell, characterized in that: The perovskite solar cell comprises a hole transport layer and a perovskite photoactive layer which are stacked; Wherein, the hole transport layer comprises the hole transport layer according to any one of claims 1 to 6.

8. The perovskite solar cell according to claim 7, characterized in that: The perovskite solar cell also includes a transparent conductive substrate, an electron transport layer, a hole blocking layer and a counter electrode; The transparent conductive substrate, the hole transport layer, the perovskite photoactive layer, the electron transport layer, the hole blocking layer and the counter electrode are stacked in sequence.

9. A method for preparing a perovskite solar cell, characterized in that: The following operations are included: A transparent conductive substrate is provided, wherein NiO is stacked on the transparent conductive substrate x layer; The first solution method is used to prepare the NiO x Prepare a self-assembled monolayer on the layer; preparing a perovskite photoactive layer on the self-assembled monolayer by a second solution method; Wherein, when preparing the self-assembled monolayer, the precursor solution used includes the self-assembled monolayer material and additives; The structural formula of the additive is HO(CH2) n COOH; Wherein, n is a positive integer greater than or equal to 1.

10. The method for preparing a perovskite solar cell according to claim 9, characterized in that: In the precursor solution, the concentration of the self-assembled monomolecular material is 0.4 mg / ml to 1 mg / ml; The concentration of the additive is 0.2 mg / ml to 0.8 mg / ml; and / or In the precursor solution, the solvent includes at least one of ethanol and isopropanol; and / or The first solution method and the second solution method independently include at least one of a spin coating method, a dip coating method, and a slit coating method.

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