Self-assembled monolayer solution, self-assembled monolayer and perovskite solar cell thereof

Abstract

The invention provides a self-assembled monolayer solution, a self-assembled monolayer and a perovskite solar cell thereof. The self-assembled monolayer solution includes a self-assembled monomolecular material, an additive, and a solvent, the additive including a compound of formula A as described herein. According to the invention, the compound in the formula A is used as an additive to be added into the self-assembled single layer, so that the wettability of the self-assembled single layer can be improved, a 2D / 3D perovskite heterojunction can be formed at a bottom interface to passivate bottom defects, carrier transport and extraction are facilitated, and the photovoltaic performance of the perovskite solar cell is improved.

Description

Technical Field

[0001] This invention relates to the field of solar cells, and particularly to a self-assembled monolayer solution, a self-assembled monolayer, and a perovskite solar cell thereof. Background Technology

[0002] Perovskite solar cells have attracted much attention due to their high conversion efficiency, making them a popular research topic. However, defects at the interface of three-dimensional (3D) perovskites can degrade the performance and operational stability of perovskite solar cells due to charge recombination, ion migration, and electric field inhomogeneity.

[0003] By employing interface defect passivation strategies, functional materials with special functional groups can be introduced between the active layer and the transport layer to effectively suppress defects and non-radiative recombination, thereby improving battery performance. Among these strategies, constructing 2D / 3D perovskite heterojunctions at the 3D perovskite interface is an effective passivation technique. However, research on 2D / 3D perovskite heterojunction passivation at the bottom interface is limited, and perovskite nucleation and heterojunction formation are closely related to the film quality and wettability of the underlying self-assembled monolayer (SAM). Therefore, finding a material that can both improve the wettability of the SAM film and form 2D / 3D perovskite heterojunctions at the bottom interface is crucial for enhancing the performance of perovskite solar cells.

[0004] Researchers at Chongqing University, including Zang Zhigang and Chen Jiangzhao, introduced a small amount of 2-aminoindane hydrochloride into the perovskite precursor solution, forming a bottom-up 2D / 3D heterojunction at the bottom interface. This controlled perovskite crystallization, passivated 3D perovskite grain boundary defects, optimized the energy level arrangement at the buried interface, and significantly suppressed nonradiative recombination losses at the buried interface. De Wolf et al. at King Abdullah University of Science and Technology mixed 4-hydroxybenzylamine ligands into a 2PACz-SAM solution and then coated it onto ITO. FTIR results of the solid-state mixed powder in their article confirmed that the amino groups of the HBzA molecule reacted with the phosphonic acid groups of 2PACz to form ionic bonds.

[0005] Currently, SAM modification and perovskite interface passivation are carried out in steps, which are cumbersome and hinder commercialization. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a self-assembled monolayer solution, a self-assembled monolayer, and a perovskite solar cell thereof. By adding compound A as an additive to the self-assembled monolayer, this invention improves the wettability of the self-assembled monolayer and simultaneously forms a 2D / 3D perovskite heterojunction at the bottom interface, passivating bottom defects and improving carrier transport and extraction capabilities.

[0007] The first aspect of this invention provides a self-assembled monolayer solution, the self-assembled monolayer solution comprising a self-assembled monomolecular material, an additive, and a solvent, wherein the additive comprises a compound represented by formula A:

[0008]

[0009] In the formula:

[0010] R1 is selected from hydroxyl, hydroxyl-substituted C1-10 alkyl, carboxyl, carboxyl-substituted C1-10 alkyl, amino, and NH3. + Substituted C1-10 alkyl groups;

[0011] R2 is selected from an amino group or NH3. + Substituted C1-C10 alkyl groups;

[0012] X - It is an acid radical ion;

[0013] n is 1 or 2.

[0014] In one or more embodiments, the self-assembled monomolecular material is selected from one or more of Me-4PACz, MeO-4PACz, and 2PACz.

[0015] In one or more embodiments, R2 is selected from NH3. + Substituted C1-C4 alkyl groups or NH3 + Substituted C1-C2 alkyl groups.

[0016] In one or more embodiments, the anion is one or more of chloride, iodide, and bromide ions.

[0017] In one or more embodiments, the compound of formula A is one or more of 4-(2-ammonium methyl)cyclohexanol iodide, 4-(2-ammonium ethyl)cyclohexanol iodide, 4-(ammonium methyl)cyclohexane carboxylic acid iodide, 4-(ammonium ethyl)cyclohexammonium diiodide, and 4-(aminomethyl)cyclohexane carboxylate ammonium chloride.

[0018] In one or more embodiments, the concentration of compound A in the self-assembled monolayer solution is 0.3 mg / mL to 1.2 mg / mL.

[0019] In one or more embodiments, the solvent is ethanol and / or isopropanol.

[0020] A second aspect of the present invention provides a self-assembled monolayer comprising an additive and a self-assembled monomolecule material; the additive comprising a compound of formula A as described in any embodiment herein.

[0021] In one or more embodiments, the self-assembled monomolecular material is selected from one or more of Me-4PACz, MeO-4PACz, and 2PACz.

[0022] A third aspect of the present invention provides a method for preparing a self-assembled monolayer as described in any embodiment herein, the method comprising: coating a self-assembled monolayer solution as described in any embodiment herein onto the surface of a substrate, and annealing thereon to obtain the self-assembled monolayer.

[0023] In one or more embodiments, the substrate is a hole transport layer or a perovskite photoactive layer.

[0024] In one or more embodiments, the coating method is selected from one or more processes such as spin coating, slot coating, blade coating, spray coating, screen printing, and inkjet printing.

[0025] In one or more embodiments, the annealing temperature is 80-120°C and the annealing time is 3-15 min.

[0026] A fourth aspect of the present invention provides a perovskite solar cell comprising a self-assembled monolayer as described in any embodiment herein.

[0027] In one or more embodiments, the perovskite solar cell includes, in sequence, a transparent glass, a conductive electrode, a hole transport layer, a self-assembled monolayer as described in any embodiment herein, a perovskite photoactive layer, an electron transport layer, a buffer layer, a transparent electrode, and a top electrode.

[0028] In one or more embodiments, the conductive electrode is made of ITO.

[0029] In one or more embodiments, the hole transport layer is made of NiOx.

[0030] In one or more embodiments, the active material of the perovskite photoactive layer is an ABX3 compound containing a three-dimensional structure; A is a monovalent cation, including but not limited to one or a mixture of several monovalent cations selected from cesium, rubidium, methylamino, and formamidinium; B is a divalent cation, including but not limited to one or a mixture of several divalent cations selected from lead, copper, zinc, gallium, tin, and calcium; X is a monovalent anion, including but not limited to one or a mixture of several monovalent anions selected from iodine, bromine, chloride, fluorine, and thiocyanate ions.

[0031] In one or more embodiments, the active material of the perovskite photoactive layer is an ABX3 compound with a three-dimensional structure; A is Cs and FA, B is Pb, and C is I and Br.

[0032] In one or more embodiments, the electron transport layer is made of C60.

[0033] In one or more embodiments, the material of the buffer layer is SnO2.

[0034] In one or more embodiments, the perovskite solar cell is an inverted perovskite solar cell.

[0035] A fifth aspect of the present invention provides the application of the compound of formula A as described in any embodiment herein in improving the wettability of self-assembled monolayers and promoting the formation of 2D / 3D perovskite heterojunctions at the contact interface between the self-assembled monolayer and the perovskite, thereby enhancing carrier transport and extraction capabilities.

[0036] The sixth aspect of the present invention provides the use of compound A as described in any embodiment herein in the preparation of perovskite solar cells with enhanced photovoltaic performance;

[0037] A seventh aspect of the present invention provides the application of self-assembled monolayers as described in any embodiment herein in the fabrication of perovskite solar cells with enhanced photovoltaic performance.

[0038] The beneficial effects of this invention are:

[0039] This invention adds compound A as an additive to a self-assembled monolayer solution, which improves the wettability of the self-assembled monolayer and simultaneously forms a 2D / 3D perovskite heterojunction at the bottom interface to passivate bottom defects. This facilitates carrier transport and extraction, thereby improving the photovoltaic performance of perovskite solar cells. The preparation method of this invention is simple, enhances device performance, and saves production costs. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell according to one embodiment of the present invention.

[0041] Figure 2 The PL and TRPL test curves are shown for the examples and comparative examples; wherein, as Figure 2 (a) Photoluminescence spectrum curves of Examples 1, 5 and Comparative Example 2; Figure 2 (b) is a partially magnified photoluminescence spectrum of Examples 1, 5 and Comparative Example 2; Figure 2 (c) shows the TRPL spectra of Examples 1, 5 and Comparative Example 2. Detailed Implementation

[0042] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0043] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0044] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0045] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0046] Unless otherwise specified, percentages refer to mass percentages and proportions refer to mass ratios in this article.

[0047] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope defined by the claims.

[0048] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0049] This invention provides a self-assembled monolayer solution comprising a self-assembled monomolecule material, an additive, and a solvent. The additive comprises a compound of formula A, the structure of which is as follows:

[0050]

[0051] In the formula:

[0052] R1 is selected from hydroxyl, hydroxyl-substituted C1-10 alkyl, carboxyl, carboxyl-substituted C1-10 alkyl, amino, and NH3. + Substituted C1-10 alkyl groups;

[0053] R2 is selected from an amino group or NH3. + Substituted C1-C10 alkyl groups;

[0054] X- It is an acid radical ion;

[0055] n is 1 or 2.

[0056] In some implementations, R1 and R2 are opposite, intermediate, or adjacent.

[0057] In some implementations, R2 is selected from NH3. + Substituted C1-C4 alkyl groups or NH3 + Substituted C1-C2 alkyl groups.

[0058] In some implementations, the anion is one or more of iodide, chloride, and bromide ions.

[0059] In some specific embodiments, compound A is 4-(2-ammonium methyl)cyclohexanol iodide, with the following structural formula:

[0060]

[0061] In some specific embodiments, compound A is 4-(2-ammonium ethyl)cyclohexanol iodide, with the following structural formula:

[0062]

[0063] In some specific embodiments, compound A is 4-(ammonium methyl)cyclohexanecarboxylic acid iodide, with the following structural formula:

[0064]

[0065] In some specific embodiments, compound A is 4-(ammonium ethyl)cyclohexammonium diiodide, with the following structural formula:

[0066]

[0067] In some specific embodiments, compound A is 4-(aminomethyl)cyclohexanecarboxylic acid, with the following structural formula:

[0068]

[0069] In some embodiments, the compound of formula A, the self-assembled monomolecule material, and the solvent are mixed to obtain a self-assembled monolayer solution. The type of solvent is not particularly limited and can be selected from organic solvents conventionally used in the art, such as one or more selected from isopropanol, ethanol, methanol, and N,N-dimethylformamide.

[0070] In some embodiments, the mass concentration of compound A in the self-assembled monolayer solution is 0.3-1.2 mg / mL, such as 0.5 mg / mL-1 mg / mL.

[0071] In some embodiments, the self-assembled monomolecular material is selected from one or more of Me-4PACz ((4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid), MeO-4PACz (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid), and 2PACz (ethyl 2-[(2-chlorophenyl)(phenyl)amino]benzoate). The concentration of the self-assembled monomolecular material can be the concentration conventionally used in the art for preparing self-assembled monomolecular solutions. In some embodiments, the molar concentration of the self-assembled monomolecular material is 0.5-1.6 mM.

[0072] The self-assembled monolayer of this invention can be prepared using a solution method.

[0073] In some embodiments, the present invention also provides a method for preparing a self-assembled monolayer, which includes coating a self-assembled monolayer solution onto the surface of a substrate and annealing it to obtain a self-assembled monolayer.

[0074] In this invention, a spin-coating process can be used to coat a self-assembled monolayer solution onto the surface of a substrate, such as a hole transport layer, a perovskite photoactive layer, or an electrode. The coating thickness of the self-assembled monolayer solution on the substrate surface can be adjusted according to the target thickness of the self-assembled monolayer. In the spin-coating process, the spin-coating speed is 2000-5000 rpm, such as 3000-4000 rpm; the spin-coating time is 10-25 s, such as 15-20 s.

[0075] In this invention, the coating method may also include one or more processes selected from spin coating, blade coating, spray coating, screen printing, and inkjet printing. The parameters of these processes can be adjusted according to the target thickness of the self-assembled monolayer.

[0076] After coating, the coating undergoes annealing. The purpose of annealing is to remove the solvent. The annealing temperature can be 80-120°C, such as 100-110°C. An exemplary annealing time can be 3-15 minutes, such as 5-10 minutes. After annealing, a self-assembled monolayer is obtained.

[0077] Therefore, the present invention also provides a self-assembled monolayer comprising an additive, a self-assembled monomolecule material, and a solvent; the additive comprising a compound of formula A as described above.

[0078] In this invention, the thickness of the self-assembled monolayer can be 1-5 nm, such as 2-3 nm.

[0079] Perovskite solar cells

[0080] The present invention also provides a perovskite solar cell comprising a self-assembled monolayer as described herein.

[0081] The present invention also provides a method for fabricating a perovskite solar cell, which includes the steps of sequentially disposing of a conductive electrode, a hole transport layer, a self-assembled monolayer as described herein, a perovskite photoactive layer, an electron transport layer, a buffer layer, a transparent electrode, and a top electrode on a transparent glass substrate from bottom to top. The self-assembled monolayer described herein can be fabricated using the steps for preparing a self-assembled monolayer as described herein.

[0082] Therefore, the perovskite solar cell of the present invention may include, from bottom to top, a transparent glass, a conductive electrode, a hole transport layer, a self-assembled monolayer as described herein, a perovskite photoactive layer, an electron transport layer, a buffer layer, a transparent electrode, and a top electrode. This perovskite solar cell is an inverted perovskite solar cell. In the present invention, the perovskite solar cell may also be a conventional perovskite solar cell.

[0083] Materials suitable for the conductive electrodes of this invention include, but are not limited to, one or more of FTO, ITO, and IZO. The fabrication of the conductive electrodes is not particularly limited; conventional methods for fabricating conductive electrodes in the art can be used, such as magnetron sputtering. Process parameters can be adjusted according to the target thickness of the conductive electrode. In some embodiments, the conductive electrode is ITO. In some embodiments, the thickness of the conductive electrode is 50-300 nm, such as 100-300 nm.

[0084] Materials suitable for the hole transport layer of this invention include, but are not limited to, one or more of SAM, NiOx, PEDOT:PSS, and PTAA. The preparation of the hole transport layer is not particularly limited, and conventional methods for preparing hole transport layers in the art can be used, such as spin coating, blade coating, or slot coating processes. Process parameters can be adjusted according to the target thickness of the hole transport layer. In some embodiments, the hole transport layer is a NiOx layer. In some embodiments, the thickness of the NiOx layer is 10-80 nm, such as 15-30 nm.

[0085] The active material of the perovskite photoactive layer suitable for this invention is an ABX3 compound containing a three-dimensional structure; A is a monovalent cation, including but not limited to one or a mixture of several monovalent cations selected from cesium (Cs), rubidium (Rb), methylamino (CH3NH3, MA), and formamidinyl (CH2(NH2)2, FA); B is a divalent cation, including but not limited to one or a mixture of several divalent cations selected from lead (Pb), copper (Cu), zinc (Zn), gallium (Ga), tin (Sn), and calcium (Ca); X is a monovalent anion, including but not limited to one or a mixture of several monovalent anions selected from iodine (I), bromine (Br), chloride (Cl), fluorine (F), and thiocyanate (SCN). In some embodiments, A is Cs and FA, B is Pb, and C is I and Br. In some specific embodiments, the active material of the perovskite photoactive layer is Cs.0.22 FA 0.78 Pb(I 0.85 Br 0.15 3. The preparation of the perovskite photoactive layer is not particularly limited, and conventional methods for preparing perovskite photoactive layers in the art can be used, such as spin coating, slot coating, blade coating, spray coating, screen printing, inkjet printing, etc. In some embodiments, a perovskite precursor solution is coated on the surface of the self-assembled monolayer to obtain the perovskite photoactive layer. In some embodiments, a blade coating process is used to coat the perovskite precursor solution on the surface of the self-assembled monolayer to obtain the perovskite photoactive layer. In some embodiments, the thickness of the perovskite photoactive layer is 10 nm to 100 μm, such as 400-600 nm; the band gap is 0.9 to 3.0 eV.

[0086] Materials suitable for the electron transport layer of this invention include, but are not limited to, C60, tin oxide, zinc oxide, and titanium oxide. The preparation of the electron transport layer is not particularly limited, and conventional methods in the art can be used, such as thermal evaporation or magnetron sputtering. Process parameters can be adjusted according to the target thickness of the electron transport layer. In some embodiments, the material of the electron transport layer is C60. In some embodiments, the thickness of the electron transport layer is 10-30 nm, such as 13-17 nm.

[0087] Materials suitable for the buffer layer of this invention include, but are not limited to, SnO2, PCBM, BCP, and MoO. x One or more of the following are acceptable materials: The preparation of the buffer layer is not particularly limited, and conventional methods for preparing buffer layers in the art can be used, such as thermal evaporation. Process parameters can be adjusted according to the target thickness of the buffer layer. In some embodiments, the material of the buffer layer is SnO2. In some embodiments, the thickness of the buffer layer is 5nm-50nm, such as 10-20nm.

[0088] Materials suitable for the transparent electrode of this invention include, but are not limited to, one or more of FTO, ITO, and IZO. The preparation of the transparent electrode is not particularly limited; conventional methods for preparing transparent electrodes in the art can be used, such as thermal evaporation. Process parameters can be adjusted according to the target thickness of the transparent electrode. In some embodiments, the transparent electrode is IZO. In some embodiments, the thickness of the transparent electrode is 20-200 nm, such as 40-80 nm.

[0089] The material suitable for the top electrode of this invention can be selected from at least one of gold, silver, copper, aluminum, and carbon. In some embodiments, the material of the top electrode is silver. In some embodiments, the thickness of the top electrode is 200 nm-800 nm, such as 300-500 nm.

[0090] In some embodiments, the perovskite solar cell of the present invention is a single-junction perovskite solar cell or a tandem perovskite solar cell. Exemplary tandem perovskite solar cells include two-terminal tandem cells, three-terminal tandem cells, and four-terminal tandem cells.

[0091] The present invention will be described below by way of specific embodiments. It should be understood that these embodiments are merely illustrative and are not intended to limit the scope of the invention. The methods, reagents, and materials used in the embodiments are conventional methods, reagents, and materials in the art, unless otherwise stated. The raw material compounds in the embodiments are all commercially available.

[0092] Example 1

[0093] (1) Transparent glass, 3mm thick;

[0094] (2) An ITO layer with a thickness of 200 nm was prepared on transparent glass by magnetron sputtering.

[0095] (3) After ultrasonically cleaning the ITO layer prepared in step (2) with detergent water, deionized water, acetone and ethanol for 20 min each, NiO was prepared on the ITO layer by magnetron sputtering. X The layer is 20nm thick;

[0096] (4) Compound A, 4-(2-ammonium methyl)cyclohexanol iodide, was added as a SAM additive to a solution of [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphoric acid (Me-4pacz), wherein the solvent was ethanol and the concentration of Me-4pacz was 1.0 mM. The concentration of the added compound A was 0.5 mg / mL. The above solution was then spin-coated onto NiO. X A SAM layer was prepared on the substrate using the following process parameters: spin-coating at 4000 rpm for 15 s, followed by annealing at 100 °C for 10 min, resulting in a thickness of 2-3 nm. The molecular structure of compound A is as follows:

[0097]

[0098] (5) 1.7M Cs were prepared by the blade coating method. 0.22 FA 0.78 Pb(I 0.85 Br 0.15 )3 Perovskite is used as the active layer, with a thickness of 500 nm;

[0099] (6) A C60 layer with a thickness of 15 nm was prepared by thermal evaporation;

[0100] (7) A SnO2 layer with a thickness of 15 nm was prepared by thermal evaporation;

[0101] (8) An IZO layer with a thickness of 50 nm was prepared by thermal evaporation;

[0102] (9) Ag was prepared by thermal evaporation with a thickness of 400 nm to complete the battery preparation.

[0103] The perovskite solar cells produced are as follows Figure 1 As shown, from bottom to top, it includes a transparent glass layer, a conductive electrode, a hole transport layer, a self-assembled monolayer, a perovskite photoactive layer, an electron transport layer, a buffer layer, a transparent electrode, and a silver electrode.

[0104] Example 2

[0105] The only difference from Example 1 is that the concentration of compound A in step (4) of Example 2 is 1 mg / mL. All other operating steps and conditions are the same as in Example 1.

[0106] Example 3

[0107] The only difference from Example 1 is that in Example 3, the compound of formula A in step (4) is 4-(2-ammonium ethyl)cyclohexanol iodide, the concentration of compound A is 0.5 mg / mL, and the molecular formula is as follows:

[0108]

[0109] All other operating steps and conditions are the same as in Example 1.

[0110] Example 4

[0111] The only difference from Example 3 is that the concentration of compound A in step (4) of Example 4 is 1 mg / mL. All other operating steps and conditions are the same as in Example 3.

[0112] Example 5

[0113] The only difference from Example 1 is that in Example 5, the compound of formula A in step (4) is 4-(ammonium methyl)cyclohexane carboxylic acid iodide, the concentration of compound A is 0.5 mg / mL, and the molecular formula is as follows:

[0114]

[0115] All other operating steps and conditions are the same as in Example 1.

[0116] Example 6

[0117] The only difference from Example 5 is that the concentration of compound A in step (4) of Example 6 is 1 mg / mL. All other operating steps and conditions are the same as in Example 5.

[0118] Example 7

[0119] The only difference from Example 1 is that in Example 7, the compound of formula A in step (4) is 4-(ammonium ethyl)cyclohexammonium diiodide, the concentration of compound A is 0.5 mg / mL, and the molecular formula is as follows:

[0120]

[0121] All other operating steps and conditions are the same as in Example 1.

[0122] Example 8

[0123] The only difference from Example 7 is that the concentration of compound A in step (4) of Example 8 is 1 mg / mL. All other operating steps and conditions are the same as in Example 7.

[0124] Example 9

[0125] The only difference from Example 1 is that in Example 9, the compound of formula A in step (4) is 4-(aminomethyl)cyclohexanecarboxylic acid, the concentration of compound A is 0.5 mg / mL, and the molecular formula is as follows:

[0126]

[0127] All other operating steps and conditions are the same as in Example 1.

[0128] Comparative Example 1

[0129] The only difference from Example 1 is that the compound of formula A in step (4) of Comparative Example 1 is 9-carboxynonamine iodide. The difference between the molecules in the examples is that the intermediate group R in Comparative Example 1 is a straight-chain alkane, while R in the molecule of the examples contains a six-membered ring, and its molecular formula is as follows:

[0130]

[0131] All other operating steps and conditions are the same as in Example 1.

[0132] Comparative Example 2

[0133] The only difference from Example 1 is that in Comparative Example 2, only Me-4pacz was used in step (4), without the SAM additive. All other operating steps and conditions were the same as in Example 1.

[0134] Comparative Example 3

[0135] The only difference from Example 1 is that compound A is replaced with 4-hydroxybenzylammonium iodide. All other operating steps and conditions are the same as in Example 1.

[0136] Test Example 1

[0137] 1. Photoelectric Testing: Photoelectric testing was performed on the perovskite solar cells prepared in Examples 1-9 and Comparative Examples 1-3. The test temperature was 25±1℃. The current density-voltage curves (J-V curves) of the devices were obtained using a source meter (Keithley 2400) on an ABET Sun 3000 solar simulator at AM1.5G (100mW / cm²). 2 Obtained under illumination, the battery area is 1 cm². 2 Before testing, the light intensity was calibrated using a standard silicon cell, and the scan rate was 20mV / s.

[0138] Wherein, the open-circuit voltage VOC is the terminal voltage of the cell in the open-circuit state. The short-circuit current JSC is the current density that the perovskite solar cell can generate under short-circuit conditions. The fill factor FF is the ratio of the maximum power of the solar cell to the product of the open-circuit voltage and the short-circuit current. The photoelectric conversion efficiency PCE can be calculated by measuring the current density-voltage curves (JV curves) of the solar cell.

[0139] 2. Water Contact Angle Test: The water contact angle of the self-assembled monolayers prepared in Examples 1-9 and Comparative Examples 1-3 was tested. This test process involved testing the self-assembled monolayers first during the preparation of the examples and comparative examples, followed by subsequent preparations. The test method was as follows: Under ultra-low humidity (<5%), inert atmosphere (N2), and light-protected conditions, a small droplet of ultrapure water (2-5 μL) was used, and an image was captured instantaneously (within 1-3 seconds) after droplet deposition. The initial contact angle value was calculated using the Young-Laplace fitting method.

[0140] The test data above are shown in Table 1 below.

[0141] Table 1

[0142] <![CDATA[Jsc(mA / cm 2 )]]> Voc(V) FF (%) Eff(%) Water contact angle (°) Example 1 18.94 1.254 78.01 18.54 76.3 Example 2 18.74 1.229 78.15 17.99 77.8 Example 3 18.74 1.233 78.16 18.05 78.2 Example 4 18.78 1.225 78.45 18.04 79.5 Example 5 19.37 1.231 80.52 19.18 73.1 Example 6 18.78 1.225 78.45 18.04 74.5 Example 7 19.71 1.213 78.42 18.76 76.1 Example 8 19.54 1.209 78.61 18.57 75.8 Example 9 19.34 1.229 78.49 18.65 74.9 Comparative Example 1 18.73 1.191 76.27 17.93 82.5 Comparative Example 2 18.61 1.190 77.72 17.21 84.7 Comparative Example 3 18.63 1.185 76.65 16.92 81.9

[0143] The device performance is shown in Table 1. The devices prepared in Examples 1-9 are superior to those in Comparative Examples 1-3 in terms of photovoltaic parameters such as short-circuit current, open-circuit voltage, fill factor, and photoelectric conversion efficiency. Furthermore, water contact angle tests revealed that the water contact angles of Examples 1-9 are all lower than those of Comparative Examples 1-3, indicating that the SAM additive in these examples can effectively improve the wettability of SAM, which is beneficial for subsequent perovskite thin film deposition.

[0144] Test Example 2

[0145] The perovskite films prepared in Examples 1, 5, and Comparative Example 1 were subjected to photoluminescence (PL) and time-resolved photoluminescence (TRPL) tests. PL involves exciting the sample with a continuous light source and measuring stable fluorescence emission to reveal the fluorescence properties and electronic structure of the material. TRPL utilizes a pulsed light source to measure fluorescence decay in detail and investigate carrier dynamics, such as lifetime and recombination processes.

[0146] Examples 1, 5, and Comparative Example 2 were selected for PL and TRPL testing, as follows: Figure 2 (a) is the photoluminescence spectrum curve of Examples 1, 5 and Comparative Example 2. Figure 2 (b) shows magnified photoluminescence spectra of Examples 1, 5, and Comparative Example 2 at wavelengths around 500-650 nm. It can be seen that the photoluminescence intensity of the perovskite films modified in Examples 1 and 5 is significantly enhanced, with the film of Example 5 exhibiting the strongest photoluminescence intensity. This demonstrates that the additive-modified molecules of the present invention can more effectively passivate defects in perovskite films and suppress nonradiative recombination of charge carriers. Figure 2 In (b), it can be observed that the films treated in Examples 1 and 5 both exhibit 2D PVSK characteristic peaks, and the corresponding PL peak values ​​are marked in the figure. The peak value corresponding to the 2DPVSK characteristic peak is the 2D perovskite characteristic peak value that appears at the bottom interface.

[0147] Figure 2 (c) shows the TRPL spectra of Examples 1, 5, and Comparative Example 2. It can be observed that the perovskite film of Comparative Example 2 has the shortest carrier lifetime, while the lifetimes of the modified perovskite films of Examples 1 and 5 are extended. The increase in photoluminescence intensity and carrier lifetime indicates that the grain size is increased, the crystallinity is improved, the morphology of the perovskite film is improved, and the interface defect is effectively passivated, thus effectively suppressing nonradiative recombination.

Claims

1. A self-assembled monolayer solution, characterized in that, The self-assembled monolayer solution comprises a self-assembled monomolecular material, an additive, and a solvent, wherein the additive comprises a compound represented by formula A: Where: R1 is selected from hydroxyl, hydroxyl-substituted C1-10 alkyl, carboxyl, carboxyl-substituted C1-10 alkyl, amino, and NH3. + Substituted C1-10 alkyl groups; R2 is selected from an amino group or NH3. + Substituted C1-C10 alkyl groups; X - It is an acid radical ion; n is 1 or 2.

2. The self-assembled monolayer solution as described in claim 1, characterized in that, The self-assembled monomolecular material is selected from one or more of Me-4PACz, MeO-4PACz, and 2PACz.

3. The self-assembled monolayer solution as described in claim 1, characterized in that, R1 and R2 are opposite, intermediate, or adjacent; and / or R2 is selected from NH3 + Substituted C1-C4 alkyl groups or NH3 + Substituted C1-C2 alkyl groups.

4. The self-assembled monolayer solution as described in claim 1, characterized in that, The anion is one or more of chloride, iodide and bromide ions.

5. The self-assembled monolayer solution as described in claim 1, characterized in that, The compound of formula A is one or more of 4-(2-ammonium methyl)cyclohexanol iodide, 4-(2-ammonium ethyl)cyclohexanol iodide, 4-(ammonium methyl)cyclohexane carboxylic acid iodide, 4-(ammonium ethyl)cyclohexammonium diiodide, and 4-(aminomethyl)cyclohexane carboxylic acid chloride.

6. The self-assembled monolayer solution as described in claim 1, characterized in that, In the self-assembled monolayer solution, the concentration of compound A is 0.5 mg / mL to 1 mg / mL; and / or The solvent is ethanol and / or isopropanol.

7. A self-assembled monolayer, characterized in that, The self-assembled monolayer comprises an additive and a self-assembled monomolecule material; the additive comprises a compound of formula A as described in any one of claims 1-6.

8. The self-assembled monolayer as described in claim 7, characterized in that, The self-assembled monomolecular material is selected from one or more of Me-4PACz, MeO-4PACz, and 2PACz.

9. A method for preparing a self-assembled monolayer as described in claim 7, characterized in that, The method includes: coating the self-assembled monolayer solution according to any one of claims 1-6 onto the surface of a substrate, and annealing it to obtain the self-assembled monolayer.

10. The method as described in claim 9, characterized in that, The coating method is selected from one or more processes among spin coating, slot coating, blade coating, spray coating, screen printing, and inkjet printing; and / or The annealing temperature is 100-110℃, and the annealing time is 5-10 minutes.

11. A perovskite solar cell comprising the self-assembled monolayer as described in claim 7 or 8.

12. The perovskite solar cell according to claim 11, characterized in that, The perovskite solar cell comprises, in sequence, a transparent glass, a conductive electrode, a hole transport layer, a self-assembled monolayer as described in claim 7, a perovskite photoactive layer, an electron transport layer, a buffer layer, a transparent electrode, and a top electrode.

13. The perovskite solar cell according to claim 12, characterized in that, The perovskite solar cell has one or more of the following characteristics: The material of the conductive electrode is ITO; The hole transport layer is made of NiOx; The active material of the perovskite photoactive layer is an ABX3 compound containing a three-dimensional structure; A is a monovalent cation, including but not limited to one or a mixture of several monovalent cations selected from cesium, rubidium, methylamino, and formamidinium; B is a divalent cation, including but not limited to one or a mixture of several divalent cations selected from lead, copper, zinc, gallium, tin, and calcium; X is a monovalent anion, including but not limited to one or a mixture of several monovalent anions selected from iodine, bromine, chloride, fluorine, and thiocyanate ions; for example, A is Cs and FA, B is Pb, and C is I and Br; The electron transport layer is made of C60. The material of the buffer layer is SnO2.

14. Selected from the following applications: Application of the compound of formula A as described in any one of claims 1-6 in improving the wettability of self-assembled monolayers and promoting the formation of 2D / 3D perovskite heterojunctions at the contact interface between the self-assembled monolayer and the perovskite, thereby enhancing carrier transport and extraction capabilities. Application of compound A as described in any one of claims 1-6 in the preparation of perovskite solar cells with improved photovoltaic performance; The application of the self-assembled monolayer as described in any one of claims 1-6 in the fabrication of perovskite solar cells with enhanced photovoltaic performance.

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