Composition for self-assembled monomolecular layer, perovskite solar cell and preparation method

Abstract

The invention provides a composition for a self-assembled monomolecular layer, and belongs to the technical field of photovoltaic cells. The composition for the self-assembled monomolecular layer comprises a self-assembled monomolecular layer material and a dopant with a structure as shown in a formula (1), formula (1); wherein R1 is selected from OH or C1-C3 alkyl groups; and R2 is selected from at least one fluorine-substituted C1-C3 alkyl group. According to the present invention, by using the strong polarity interaction between the fluoroalkoxy of the dopant and the SAMs material, the agglomeration of the SAMs material is inhibited, the uniform SAMs layer is formed, and the photo-generated hole extraction capability of the cell is improved. Meanwhile, the self-assembled monomolecular layer disclosed by the invention is beneficial to improving the crystal quality of the perovskite layer, thereby being beneficial to improving the photoelectric conversion efficiency of the perovskite cell.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of photovoltaic cells, and in particular to a self-assembled monolayer composition, a perovskite solar cell and a preparation method. BACKGROUND

[0002] In recent years, perovskite solar cells have been widely used in various fields, such as photovoltaic buildings, mobile devices and electronic products, etc. Generally, a perovskite solar cell includes a transparent conductive substrate, a hole transport layer and a perovskite light-absorbing layer, etc. To improve the hole extraction and transport efficiency, a self-assembled monolayer (SAMs) can be added between the hole transport layer and the perovskite light-absorbing layer.

[0003] However, the self-assembled monolayer is prone to uneven film formation during preparation, which greatly affects the hole extraction capability and photoelectric conversion efficiency of the perovskite solar cell. SUMMARY

[0004] Therefore, in order to at least partially solve at least one of the above-mentioned technical problems, the present disclosure provides a self-assembled monolayer composition, a perovskite solar cell and a preparation method.

[0005] According to an embodiment of one aspect of the present disclosure, a self-assembled monolayer composition is provided, comprising: a self-assembled monolayer material and a dopant having a structure as shown in formula (I);

[0006] , (Formula 1); wherein R1 is selected from OH or C1-C3 alkyl; R2 is selected from at least one fluorine-substituted C1-C3 alkyl.

[0007] According to an embodiment of another aspect of the present disclosure, a perovskite solar cell is provided, comprising: a substrate; and a transparent conductive layer, a hole transport layer, a self-assembled monolayer, a perovskite light-absorbing layer, an electron transport layer and an electrode arranged in sequence on the substrate; wherein the self-assembled monolayer comprises a self-assembled monolayer composition.

[0008] According to an embodiment of still another aspect of the present disclosure, a preparation method of a perovskite solar cell is provided, comprising: providing a cell substrate, the cell substrate comprising a substrate, a transparent conductive layer and a hole transport layer arranged in sequence; coating an organic solution containing a self-assembled monolayer composition on the hole transport layer of the cell substrate to obtain a self-assembled monolayer; coating a perovskite solution on the self-assembled monolayer, and obtaining a perovskite light-absorbing layer after heating annealing; and preparing an electron transport layer and an electrode in sequence on the perovskite light-absorbing layer.

[0009] According to embodiments of this disclosure, a strong interaction can be formed between the fluoroalkoxy group of the dopant and the SAMs material, which inhibits the aggregation of the SAMs material itself, thereby forming a more uniform SAMs layer. This avoids the recombination of photogenerated carriers caused by thin film pores, greatly improves the extraction capability of photogenerated holes, and thus improves the photoelectric conversion efficiency of the battery.

[0010] Furthermore, the self-assembled monolayer composition of this disclosure can form a uniform SAMs layer on the hole transport layer, thereby improving the extraction and transport capabilities of photogenerated holes. Simultaneously, the self-assembled monolayer of this disclosure possesses suitable surface energy, enhancing the wettability of the perovskite solution on its surface, thus improving the crystallinity of the perovskite layer prepared by wet processing, and consequently improving the photoelectric conversion efficiency of the perovskite solar cell. In addition, the wet processing method for preparing the self-assembled monolayer and perovskite layer is relatively simple and low-cost. Attached Figure Description

[0011] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0012] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell according to an embodiment of the present disclosure;

[0013] Figure 2 The diagrams show the potential distribution of self-assembled monolayers in the embodiments and comparative examples of this disclosure, wherein (a) is the potential distribution of [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate material (Me-4PACz), (b) is the potential distribution of Me-4PACz@3-(trifluoromethoxy)benzoic acid, (c) is the potential distribution of Me-4PACz@2-(difluoromethoxy)benzoate, (d) is the potential distribution of 2,2'-bipyridine-4,4'-dicarboxylic acid (HBPDC), (e) is the potential distribution of HBPDC@3-(trifluoromethoxy)benzoic acid, and (f) is the potential distribution of HBPDC@2-(difluoromethoxy)benzoate.

[0014] Figure 3 The potential distribution diagrams are for the self-assembled monolayers of the comparative examples of this disclosure, where (a) is the potential distribution diagram of Me-4PACz@benzoic acid and (b) is the potential distribution diagram of Me-4PACz@2-(carboxycarbonyl)benzoic acid.

[0015] Figure 4These are potential distribution diagrams of self-assembled monolayers according to embodiments of this disclosure. (a) shows the potential distribution of Me-4PACz@3-(trifluoromethoxy)benzoic acid (1:1), (b) shows the potential distribution of Me-4PACz@3-(trifluoromethoxy)benzoic acid (5:1), (c) shows the potential distribution of Me-4PACz@2-(difluoromethoxy)methyl benzoate (1:1), and (d) shows the potential distribution of Me-4PACz@2-(difluoromethoxy)methyl benzoate (5:1). The potential distribution diagrams are as follows: (e) is the potential distribution diagram of HBPDC@3-(trifluoromethoxy)benzoic acid (1:1), (f) is the potential distribution diagram of HBPDC@3-(trifluoromethoxy)benzoic acid (5:1), (g) is the potential distribution diagram of HBPDC@2-(difluoromethoxy)methyl benzoate (1:1), and (h) is the potential distribution diagram of HBPDC@2-(difluoromethoxy)methyl benzoate (5:1).

[0016] Figure 5 These are morphological images of the perovskite light-absorbing layers in the embodiments and comparative examples of this disclosure, wherein (a) is NiO. x Morphology of the perovskite light-absorbing layer on the substrate, (b) is NiO x Morphology of the perovskite absorbing layer on the Me-4PACz substrate, (c) is NiO x Morphology of the perovskite light-absorbing layer on the / Me-4PACz@3-(trifluoromethoxy)benzoic acid substrate;

[0017] Figure 6 This is a schematic diagram of another structure of the perovskite solar cell disclosed herein. Detailed Implementation

[0018] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0019] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0020] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0021] In this disclosure, unless otherwise specified, the description of chemical elements usually includes the concept of isotopes with the same chemical properties. For example, the description of "hydrogen (H)" also includes the concepts of 1H (protium or H) and 2H (deuterium or D) with the same chemical properties; carbon (C) includes 12C, 13C, etc., which will not be elaborated further.

[0022] In this disclosure, the expression Ca~Cb represents that the group has a~b carbon atoms. Unless otherwise specified, the number of carbon atoms generally does not include the number of carbon atoms of the substituents.

[0023] In this disclosure, the term "alkyl" may include a branched or straight-chain saturated aliphatic monovalent hydrocarbon group having a specified number of carbon atoms. Examples of C1 to C3 alkyl groups include methyl, ethyl, n-propyl, isopropyl, etc.

[0024] In this disclosure, the expression "─" across the benzene ring indicates that the linking site is located at any position on the benzene ring where bonding can occur.

[0025] In this disclosure, A@B represents a material formed by doping A with B. For example, Me-4PACz@3-(trifluoromethoxy)benzoic acid represents a material formed by doping Me-4PACz with 3-(trifluoromethoxy)benzoic acid, and so on.

[0026] In this disclosure, the ratio in parentheses in A@B (a:b) indicates the molar ratio of A to B. For example, Me-4PACz@3-(trifluoromethoxy)benzoic acid (1:1) indicates a material doped with Me-4PACz and 3-(trifluoromethoxy)benzoic acid in a molar ratio of 1:1, and so on.

[0027] In related technologies, to improve the photoelectric conversion efficiency of perovskite solar cells and enhance the extraction and transport capabilities of photogenerated holes, self-assembled monolayers can be formed on the hole transport layer. However, self-assembled monolayer films suffer from poor uniformity and surface wettability, resulting in poor hole extraction performance of the cell. During the development of this invention, it was discovered that the self-assembled monolayer material is prone to aggregation on the substrate surface, causing uneven molecular distribution and pores in the monolayer film, significantly reducing its hole extraction capability. Therefore, the inventors have proposed a composition for self-assembled monolayers. By adding the dopant disclosed in this invention, the aggregation phenomenon of self-assembled monolayer materials used in photovoltaic cell technology during the film formation process on the surface of the inorganic hole transport layer is improved, thereby enhancing film uniformity.

[0028] Specifically, according to an embodiment of one aspect of this disclosure, a composition for self-assembled monolayers is provided, comprising: a self-assembled monolayer material and a dopant having a structure as shown in formula (I);

[0029] Equation (1);

[0030] Wherein, R1 is selected from OH or C1~C3 alkyl;

[0031] R2 is selected from at least one fluorine-substituted C1-C3 alkyl group.

[0032] According to embodiments of this disclosure, a strong interaction can be formed between the fluorinated alkyl group of the dopant and the SAMs material, which inhibits the aggregation of the SAMs material itself, thereby forming a more uniform SAMs layer. This avoids the recombination of photogenerated carriers caused by thin film pores, greatly improves the extraction capability of photogenerated holes, and thus improves the photoelectric conversion efficiency of the battery.

[0033] According to embodiments of this disclosure, R1 is selected from OH or methyl; and / or, R2 is selected from difluoromethyl or trifluoromethyl.

[0034] According to the embodiments of this disclosure, by selecting the above-mentioned R1 group, it is beneficial for the dopant and the self-assembled monolayer material to form a more uniform solution system. By selecting the above-mentioned R2 group, the electronegativity of fluorine atoms is stronger than that of directly connected carbon atoms, exhibiting an electron-withdrawing inductive effect. It can form hydrogen bonds with hydrogen atoms on SAM material, allowing SAM to pair with dopant, thereby dispersing SAM material.

[0035] According to embodiments of this disclosure, the dopant is selected from at least one of 2-(difluoromethoxy)benzoic acid, 3-(difluoromethoxy)benzoic acid, p-difluoromethoxybenzoic acid, 2-(trifluoromethoxy)benzoic acid, 3-(trifluoromethoxy)benzoic acid, p-trifluoromethoxybenzoic acid, methyl 2-(difluoromethoxy)benzoate, methyl 2-(trifluoromethoxy)benzoate, methyl 3-(trifluoromethoxy)benzoate, and methyl p-trifluoromethoxybenzoate. Preferably, the dopant is selected from 2-(difluoromethoxy)benzoic acid and 3-(difluoromethoxy)benzoic acid.

[0036] According to embodiments of this disclosure, by selecting the above-mentioned dopants, it is beneficial to improve the film uniformity of SAMs materials.

[0037] According to embodiments of this disclosure, the self-assembled monolayer material is selected from at least one of fatty acid derivatives, phospholipid derivatives, polymer derivatives, organosilane derivatives, phosphate derivatives, formic acid derivatives, and organosulfur derivative self-assembled molecular materials. Preferably, the self-assembled monolayer material is selected from [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate (Me-4PACz), [2-(9H-carbazole-9-yl)ethyl]phosphate (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), or 2,2'-bipyridine-4,4'-dicarboxylic acid (HBPDC).

[0038] According to embodiments of this disclosure, selecting the aforementioned self-assembled monolayer material is beneficial for improving its ability to extract holes.

[0039] According to embodiments of this disclosure, the molar ratio of the self-assembled monolayer material to the dopant is 5:1 to 1:1, for example, 5:1, 4:1, 3:1, 2:1 and 1:1.

[0040] According to embodiments of this disclosure, if the doping ratio of the dopant is too high, the proportion of SAMs material will be too low, resulting in a decrease in the hole extraction capability of the SAMs material; if the doping ratio of the dopant is too low, it will not be conducive to its role in improving the uniformity of SAMs film formation.

[0041] According to another aspect of this disclosure, a perovskite solar cell is provided. Figure 1 This is a schematic diagram of the structure of a perovskite solar cell according to an embodiment of the present disclosure, as shown below. Figure 1 As shown, the perovskite solar cell of this disclosure includes: a substrate 1; and a transparent conductive layer 2, a hole transport layer 3, a self-assembled monolayer 4, a perovskite light-absorbing layer 5, an electron transport layer 6, and an electrode 7 sequentially disposed on the substrate 1.

[0042] According to embodiments of this disclosure, the substrate 1 may be made of aluminosilicate glass, carbon nanotubes, etc.; the transparent conductive layer 2 may be made of ITO (In-doped SnO2), FTO (F-doped SnO2), etc.; and the electron transport layer 6 may be made of C60, methyl [6,6]-phenyl-C61-butyrate (PCBM), TiO2, WO3, Zn2SnO4, SnO2, etc. The self-assembled monolayer 4 may include a composition for self-assembled monolayers. Further, as... Figure 6 As shown, perovskite solar cells may also include a barrier layer located between the electron transport layer and the electrode layer. The electrode material can be a metal, such as silver. Specifically, a metal electrode layer may be formed on the electron transport layer.

[0043] According to embodiments of this disclosure, the self-assembled monolayer composition of this disclosure can form a uniform SAMs layer on the hole transport layer 3, thereby improving the extraction and transport capabilities of photogenerated holes. Simultaneously, a perovskite layer with good crystallinity can be formed on the SAMs layer, thereby enhancing the photoelectric conversion efficiency of the battery.

[0044] According to embodiments of this disclosure, the hole transport layer 3 is made of nickel oxide, cuprous thiocyanate, copper oxide, cuprous oxide, or copper iodide; and / or, the perovskite light-absorbing layer 5 is made of Cs. x FA y MA 1-x-y PbI3, 0≤x≤1, 0≤y≤1, and x+y≤1. For example, x can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, etc., and y can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, etc.

[0045] According to embodiments of this disclosure, a self-assembled monolayer 4, based on an inorganic material hole transport layer 3, is prepared using a wet process, which enhances its hole extraction and transport capabilities. The perovskite light-absorbing layer 5 can be made from conventional materials such as Cs. x FA y MA 1-x- y PbI3, etc.

[0046] According to another embodiment of this disclosure, a method for fabricating a perovskite solar cell is provided, comprising: providing a cell substrate, the cell substrate comprising a substrate 1, a transparent conductive layer 2, and a hole transport layer 3 sequentially disposed thereon; coating an organic solution containing a composition for self-assembling a monolayer onto the cell substrate by spin coating or blade coating to obtain a self-assembly monolayer 4; coating a perovskite solution onto the self-assembly monolayer, and obtaining a perovskite light-absorbing layer 5 after heating and annealing; and sequentially fabricating an electron transport layer 6 and an electrode 7 on the perovskite light-absorbing layer.

[0047] According to embodiments of this disclosure, the self-assembled monolayer possesses suitable surface energy, enhancing the wettability of the perovskite solution on its surface. This, in turn, improves the crystal quality of the perovskite light-absorbing layer prepared by wet processing, thereby enhancing the photoelectric conversion efficiency of the perovskite solar cell. Furthermore, the wet processing method for preparing the self-assembled monolayer and perovskite light-absorbing layer is relatively simple and cost-effective.

[0048] According to embodiments of this disclosure, the organic solution described above is an alcohol solution, and more specifically, an isopropanol solution. The concentration of the self-assembled monolayer material in the composition for self-assembled monolayers is 1-3 mmol / L. -1 For example, 1 mmol·L -1 1.5 mmol·L -1 2 mmol·L -1 2.5 mmol·L -1 and 3 mmol·L -1 .

[0049] According to embodiments of this disclosure, by selecting appropriate concentrations and solvents, it is beneficial to form a more uniform SAMs layer.

[0050] The present disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Comparative Example 1

[0052] like Figure 6 As shown, a method for preparing a perovskite solar cell involves dissolving [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate material (Me-4PACz) in isopropanol at a concentration of 2 mmol / L. -1 A battery substrate is provided, comprising a transparent conductive layer and a nickel oxide layer disposed sequentially. An isopropanol solution of Me-4PACz is coated onto the nickel oxide layer of the battery substrate by spin coating, forming a self-assembled monolayer on the nickel oxide layer. A perovskite light-absorbing layer, an electron transport layer, a barrier layer, and an electrode are sequentially formed on the self-assembled monolayer.

[0053] Example 1

[0054] The difference from Comparative Example 1 is that 3-(trifluoromethoxy)benzoic acid was added to the isopropanol solution of Me-4PACz at a molar ratio of 3:1.

[0055] Example 2

[0056] The difference from Comparative Example 1 is that methyl 2-(difluoromethoxy)benzoate was added to the Me-4PACz and isopropanol solution in a molar ratio of 3:1.

[0057] Comparative Example 2

[0058] A method for preparing a perovskite solar cell involves dissolving 2,2'-bipyridine-4,4'-dicarboxylic acid (HBPDC) in isopropanol at a concentration of 2 mmol·L⁻¹. -1 A battery substrate is provided, comprising a transparent conductive layer and a nickel oxide layer disposed sequentially. HBPDC and isopropanol solution are coated onto the nickel oxide layer of the battery substrate by spin coating, forming a self-assembled monolayer on the nickel oxide layer. A perovskite light-absorbing layer, an electron transport layer and an electrode are sequentially formed on the self-assembled monolayer.

[0059] Example 3

[0060] The difference from Comparative Example 2 is that 3-(trifluoromethoxy)benzoic acid was added to the HBPDC and isopropanol solution in a molar ratio of 3:1.

[0061] Example 4

[0062] The difference from Comparative Example 2 is that methyl 2-(difluoromethoxy)benzoate was added to the HBPDC and isopropanol solution at a molar ratio of 3:1.

[0063] Comparative Example 3

[0064] The difference from Comparative Example 1 is that benzoic acid was added to the Me-4PACz and isopropanol solution at a molar ratio of 3:1.

[0065] Comparative Example 4

[0066] The difference from Comparative Example 1 is that 2-(carboxycarbonyl)benzoic acid was added to the Me-4PACz and isopropanol solution in a molar ratio of 3:1.

[0067] Example 5

[0068] The difference from Comparative Example 1 is that 3-(trifluoromethoxy)benzoic acid was added to the Me-4PACz and isopropanol solution in a 1:1 molar ratio.

[0069] Example 6

[0070] The difference from Comparative Example 1 is that 3-(trifluoromethoxy)benzoic acid was added to the Me-4PACz and isopropanol solution at a molar ratio of 5:1.

[0071] Example 7

[0072] The difference from Comparative Example 1 is that methyl 2-(difluoromethoxy)benzoate was added to the Me-4PACz and isopropanol solution in a 1:1 molar ratio.

[0073] Example 8

[0074] The difference from Comparative Example 1 is that methyl 2-(difluoromethoxy)benzoate was added to a solution of Me-4PACz and isopropanol at a molar ratio of 5:1.

[0075] Example 9

[0076] The difference from Comparative Example 2 is that 3-(trifluoromethoxy)benzoic acid was added to the HBPDC and isopropanol solution in a 1:1 molar ratio.

[0077] Example 10

[0078] The difference from Comparative Example 2 is that 3-(trifluoromethoxy)benzoic acid was added to the HBPDC and isopropanol solution at a molar ratio of 5:1.

[0079] Example 11

[0080] The difference from Comparative Example 2 is that methyl 2-(difluoromethoxy)benzoate was added to the HBPDC and isopropanol solution in a 1:1 molar ratio.

[0081] Example 12

[0082] The difference from Comparative Example 2 is that methyl 2-(difluoromethoxy)benzoate was added to the HBPDC and isopropanol solution at a molar ratio of 5:1.

[0083] Comparative Example 5

[0084] The difference from Comparative Example 1 is that the perovskite light-absorbing layer is directly disposed on the nickel oxide layer.

[0085] When a self-assembled monolayer is deposited on a battery substrate, the surface potential changes. The greater the difference in surface potential distribution, the worse the uniformity of the self-assembled monolayer. Therefore, this disclosure characterizes the potential distribution of the self-assembled monolayer using atomic force microscopy (AFM). The size range is 10 μm × 10 μm, and the potential range is 0-200 mV. Different colors represent different potential values; the more uniform the color, the smaller the potential difference. The self-assembled monolayers of the comparative examples and embodiments of this disclosure were examined using AFM. Figure 2As shown, the self-assembled monolayer of Comparative Example 1 exhibited a large difference in potential distribution, resulting in poor film uniformity. The self-assembled monolayer of Example 1 showed a significantly reduced difference in potential distribution compared to Comparative Example 1, demonstrating a significant improvement in film uniformity. The self-assembled monolayer of Example 2 showed a significantly reduced difference in potential distribution compared to Comparative Example 1, demonstrating a significant improvement in film uniformity. The self-assembled monolayer of Comparative Example 2 exhibited a large difference in potential distribution, resulting in poor film uniformity. The self-assembled monolayer of Example 3 showed a significantly reduced difference in potential distribution compared to Comparative Example 2, demonstrating a significant improvement in film uniformity. The self-assembled monolayer of Example 4 showed a significantly reduced difference in potential distribution compared to Comparative Example 2, demonstrating a significant improvement in film uniformity. Figure 3 As shown, the potential distributions of Comparative Example 3 and Comparative Example 4 differed significantly, indicating poor film uniformity. It is evident that selecting the fluorinated alkyl benzoic acid provided in this application as the dopant improves the film uniformity of the self-assembled monolayer.

[0086] like Figure 4As shown, the self-assembled monolayer of Example 5 exhibited a significantly reduced difference in potential distribution compared to Comparative Example 1, demonstrating a significant improvement in film uniformity. Similarly, the self-assembled monolayer of Example 6 showed a significantly reduced difference in potential distribution compared to Comparative Example 1, further demonstrating a significant improvement in film uniformity. Combined with the above analysis, it can be proven that a doping ratio of Me-4PACz to 3-(trifluoromethoxy)benzoic acid within the range of 1:1 to 5:1 significantly improves the film uniformity of Me-4PACz. The self-assembled monolayer of Example 7 showed a significantly reduced difference in potential distribution compared to Comparative Example 1, demonstrating a significant improvement in film uniformity. The self-assembled monolayer of Example 8 also showed a significantly reduced difference in potential distribution compared to Comparative Example 1, demonstrating a significant improvement in film uniformity. Combined with the above analysis, it can be proven that a doping ratio of Me-4PACz to methyl 2-(difluoromethoxy)benzoate within the range of 1:1 to 5:1 significantly improves the film uniformity of Me-4PACz. The self-assembled monolayer of Example 9 showed a significant improvement in potential distribution compared to Comparative Example 2, demonstrating a significant improvement in film uniformity. The self-assembled monolayer of Example 10 also showed a significant improvement in potential distribution compared to Comparative Example 2, demonstrating a significant improvement in film uniformity. Combined with the above analysis, it can be demonstrated that a doping ratio of HBPDC to 3-(trifluoromethoxy)benzoic acid within the range of 1:1 to 5:1 significantly improves the film uniformity of HBPDC. The self-assembled monolayer of Example 11 showed a significant improvement in potential distribution compared to Comparative Example 2, demonstrating a significant improvement in film uniformity. The self-assembled monolayer of Example 12 also showed a significant improvement in potential distribution compared to Comparative Example 2, demonstrating a significant improvement in film uniformity. Combined with the above analysis, it can be demonstrated that a doping ratio of HBPDC to methyl 2-(difluoromethoxy)benzoate within the range of 1:1 to 5:1 significantly improves the film uniformity of HBPDC.

[0087] Based on the above comparative examples and embodiments, it can be demonstrated that the self-assembled monolayer composition of this disclosure has a significant effect on improving the film uniformity of different types of self-assembled monolayer materials when the ratio of self-assembled monolayer material to dopant is in the range of 1:1 to 5:1.

[0088] This disclosure further characterizes the crystallinity of the perovskite light-absorbing layer. The perovskite light-absorbing layers of Comparative Example 1, Comparative Example 3, and Example 1 were examined using a scanning electron microscope, as shown... Figure 5As shown, the perovskite light-absorbing layer of Comparative Example 3 has relatively small grains, obvious grain boundaries, and poor crystal quality; the perovskite light-absorbing layer of Comparative Example 1 has uneven grain size distribution, and its crystal quality cannot meet the requirements of high-performance devices; the perovskite light-absorbing layer of Example 1 has significantly larger grain size, fewer grain boundaries, and improved film density, resulting in a significant improvement in overall crystal quality, proving that the addition of 3-(trifluoromethoxy)benzoic acid can improve the crystal quality of the perovskite layer.

[0089] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A composition for self-assembled monolayers, comprising: Self-assembled monolayer materials and dopants having the structure shown in formula (I); Equation (1); Wherein, R1 is selected from OH or C1~C3 alkyl; R2 is selected from at least one fluorine-substituted C1-C3 alkyl group.

2. The composition for self-assembled monolayers according to claim 1, wherein, The molar ratio of the self-assembled monolayer material to the dopant is 5:1 to 1:

1.

3. The composition for self-assembled monolayers according to claim 1 or 2, wherein, R1 is selected from OH or methyl; and / or, R2 is selected from difluoromethyl or trifluoromethyl.

4. The composition for self-assembled monolayers according to claim 3, wherein, The dopant is selected from at least one of 2-(difluoromethoxy)benzoic acid, 3-(difluoromethoxy)benzoic acid, p-difluoromethoxybenzoic acid, 2-(trifluoromethoxy)benzoic acid, 3-(trifluoromethoxy)benzoic acid, p-trifluoromethoxybenzoic acid, methyl 2-(difluoromethoxy)benzoate, methyl 3-(difluoromethoxy)benzoate, methyl p-difluoromethoxybenzoate, methyl 2-(trifluoromethoxy)benzoate, methyl 3-(trifluoromethoxy)benzoate, and methyl p-trifluoromethoxybenzoate.

5. The composition for self-assembled monolayers according to claim 3, wherein, The self-assembled monolayer material is selected from at least one of the following: fatty acids, phospholipids, polymers, organosilanes, phosphates, formic acids, and organosulfur compounds.

6. The composition for self-assembled monolayers according to claim 5, wherein, The self-assembled monolayer material is selected from [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphoric acid, [2-(9H-carbazole-9-yl)ethyl]phosphoric acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, or 2,2'-bipyridine-4,4'-dicarboxylic acid.

7. A perovskite solar cell, comprising: Base; And a transparent conductive layer, a hole transport layer, a self-assembled monolayer, a perovskite light-absorbing layer, an electron transport layer, and an electrode are sequentially disposed on the substrate; The self-assembled monolayer includes the composition for self-assembled monolayers as described in any one of claims 1 to 6.

8. The perovskite solar cell according to claim 7, wherein: The hole transport layer is made of nickel oxide, cuprous thiocyanate, copper oxide, cuprous oxide or copper iodide. And / or, the material of the perovskite light-absorbing layer is selected from Cs x FA y MA 1-x-y PbI3, 0≤x≤1, 0≤y≤1.

9. A method for preparing a perovskite solar cell, comprising: A battery substrate is provided, the battery substrate comprising a substrate, a transparent conductive layer and a hole transport layer disposed sequentially thereon; An organic solution comprising the composition for self-assembled monolayer as described in any one of claims 1 to 6 is coated onto the hole transport layer of the battery substrate to obtain a self-assembled monolayer. A perovskite solution was coated onto the self-assembled monolayer, and a perovskite light-absorbing layer was obtained after heating and annealing. An electron transport layer and an electrode are sequentially fabricated on the perovskite light-absorbing layer.

10. The preparation method according to claim 9, wherein, The organic solution is an alcoholic solution, and the concentration of the self-assembled monolayer material in the composition for self-assembled monolayers is 1-3 mmol·L⁻¹. -1 .

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