Perovskite precursor solution, perovskite solar cell and preparation method thereof

Abstract

The invention relates to the technical field of solar cells, and discloses a perovskite precursor solution, a perovskite solar cell and a preparation method thereof. The perovskite precursor solution comprises a perovskite active material, an additive and a solvent, the molecular structural formula of the additive is shown as a formula I, and R is selected from one of Cl, Br and I. The additive is added into the perovskite precursor solution, so that the problem of performance reduction caused by water molecule interference when a traditional perovskite solar cell is prepared in humid air is solved, and low-cost and high-humidity compatible perovskite solar cell preparation is realized.

Description

Technical Field

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

[0002] Since their first report in 2009, perovskite solar cells have garnered widespread attention due to their remarkable photoelectric conversion efficiency (certified single-junction cell efficiency approaching 27% by 2025) and low-temperature solution processability. These properties hold great potential for realizing high-efficiency photovoltaic systems. However, conventional perovskite solar cell fabrication processes rely on inert atmospheres (such as glove boxes), which not only increases production costs but also complicates the process.

[0003] In practical applications, humidity differences between different geographic regions (e.g., north and south) significantly impact the quality of perovskite films. Early attempts to directly grow perovskite films in air suffered from low photoelectric conversion efficiency and poor stability due to problems such as phase transitions, iodine oxidation, and grain boundary defects induced by airborne water and oxygen. The demand for low-cost perovskite photovoltaics is particularly urgent in high-humidity regions such as tropical and coastal areas, but traditional production methods struggle to adapt to these conditions.

[0004] Therefore, current perovskite solar cell fabrication technologies have significant limitations in high-humidity environments, making them incapable of effectively supporting large-scale industrial applications. Consequently, developing technologies suitable for fabricating high-quality perovskite thin films in high-humidity conditions has become a critical issue that needs to be addressed. Summary of the Invention

[0005] In view of the above problems, the present application provides a perovskite precursor solution, a perovskite solar cell and a preparation method thereof, aiming to provide a technology that can prepare high-quality perovskite solar cells in a high humidity environment.

[0006] The present embodiment provides a perovskite precursor solution, comprising a perovskite active material, an additive, and a solvent; the molecular structure of the additive is shown in Formula I:

[0007]

[0008] Wherein, R is selected from one of Cl, Br, and I.

[0009] In some embodiments, the additive includes at least one of 3-bromo-4-(trifluoromethyl)pyridine, 2-bromo-5-(trifluoromethyl)pyridine, 4-chloro-3-(trifluoromethyl)pyridine, 3-iodo-4-(trifluoromethyl)pyridine, and 4-bromo-3-(trifluoromethyl)pyridine.

[0010] In some embodiments, the additive includes 4-bromo-3-(trifluoromethyl)pyridine.

[0011] In some embodiments, the perovskite active material comprises an ABX3 compound, wherein A comprises at least one of a formamidinium ion, a methylamine ion, and a cesium ion; and B comprises Pb 2+ 、Sn 2+ At least one of; X includes Cl - Br - , I - At least one of; and / or, the solvent comprises dimethylformamide and N-methylpyrrolidone.

[0012] In some embodiments, the concentration of the additive in the perovskite precursor solution is 0.1-10 mg / mL; and / or the concentration of the ABX3 compound in the perovskite precursor solution is 0.6-2 mol / L; and / or the volume ratio of the dimethylformamide and the N-methylpyrrolidone is 3:1 to 10:1.

[0013] On the other hand, an embodiment of the present application provides a perovskite solar cell, comprising a transparent conductive substrate, a first transport layer, a perovskite light absorbing layer, a second transport layer and an electrode layer stacked in sequence, wherein one of the first transport layer and the second transport layer is a hole transport layer, and the other is an electron transport layer; the perovskite light absorbing layer is prepared from the above-mentioned perovskite precursor solution under a humidity environment of 10% to 60% RH.

[0014] In some embodiments, the thickness of the perovskite light absorption layer is 300 to 900 nm; and / or the thickness of the first transmission layer is 10 to 400 nm; and / or the thickness of the second transmission layer is 10 to 60 nm; and / or the thickness of the electrode layer is 30 to 300 nm.

[0015] In some embodiments, the material of the first transport layer includes at least one of nickel oxide, self-assembled monolayer, and PTAA; and / or the material of the second transport layer is at least one of carbon 60 and (6,6)-phenyl-C61-butyric acid methyl ester.

[0016] On the other hand, an embodiment of the present application provides a method for preparing a perovskite solar cell, comprising the following steps: coating the above-mentioned perovskite precursor solution on a substrate in a humidity environment of 10% to 60% RH, and then annealing.

[0017] In some embodiments, the humidity environment is 40% to 60% RH; and / or the coating method includes at least one of blade coating, slit coating, spray coating, and evaporation; and / or the annealing temperature is 100 to 150°C.

[0018] The beneficial effects of this application are:

[0019] This application solves the problem of performance degradation caused by water molecule interference when traditional perovskite solar cells are prepared in humid air by introducing an additive of molecular structure I into the perovskite precursor solution, thereby realizing the preparation of low-cost, high-humidity compatible perovskite solar cells.

[0020] In the molecule of this additive, -CF3 groups are oriented on the surface of the perovskite to form a dense hydrophobic layer, blocking the direct contact between water molecules and the perovskite lattice; halogen atoms and pyridinic nitrogen synergistically passivate the perovskite defects, and the π conjugated system maintains the charge transfer channel; bromine atoms and uncoordinated Pb 2+ The combination inhibits non-radiative recombination; the coordination effect of the pyridine ring slows the crystallization rate, resulting in a dense, pinhole-free film. Therefore, by introducing the additive of this application, the humidity tolerance of perovskite film preparation is improved, allowing the perovskite precursor solution to stably form a film in a high humidity environment (e.g., 10-60% RH).

[0021] The present invention selects the additive and directly adds it to the perovskite precursor solution, which does not require additional process flow and is conducive to the industrialized large-scale production of perovskite solar cells.

[0022] The additive not only resists water erosion but also forms a passivation layer on the surface of the perovskite film, passivating surface defects and reducing non-radiative recombination. The additive not only increases the short-circuit current of perovskite solar cells, but also increases the open-circuit voltage. The perovskite film prepared at 60% relative humidity achieved a device photoelectric conversion efficiency of 20.35%.

[0023] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0025] Figure 1 Schematic diagram of the structure of a perovskite solar cell according to some embodiments of the present application;

[0026] Figure 2This is a process flow chart of manufacturing perovskite solar cells according to some embodiments of the present application;

[0027] Figure 3 Graphs showing the current density (J)-voltage (V) of the perovskite solar cells of Example 1 and Comparative Example 1 of the present application;

[0028] Figure 4 XRD patterns of the perovskite films of Example 1 and Comparative Example 1 of the present application;

[0029] Figure 5 2 is a graph showing the current density (J)-voltage (V) curves of the perovskite solar cells of Example 2 and Comparative Example 2 of the present application.

[0030] The accompanying drawings in the specific implementation manner are as follows:

[0031] 1-transparent conductive substrate; 2-first transmission layer; 3-perovskite light absorption layer; 4-second transmission layer; 5-electrode layer. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0033] In this application, the term "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0034] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0035] It should be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution. Some or all steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0036] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0037] The weights of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the mass described in the examples of this application may be a mass unit known in the chemical industry, such as μg, mg, g, kg, etc.

[0038] The development of air preparation technology aims to eliminate the reliance on inert atmospheres, thereby directly reducing energy consumption and plant equipment investment costs, which is in line with the core advantage of perovskite materials being "low-cost." However, existing technologies still face several challenges: First, water molecules can trigger uncontrollable phase transitions in perovskite precursors (such as FAPbI3), from a photoactive black phase (α phase) to an inactive yellow phase (δ phase), significantly reducing device performance. Second, moisture penetration accelerates the formation of the PbI2 phase at perovskite grain boundaries, resulting in increased interface defects and inhibiting carrier transport.

[0039] Based on this, the embodiment of the present application proposes a perovskite precursor solution, including a perovskite active material, an additive and a solvent; the molecular structure of the additive is shown in Formula I:

[0040]

[0041] Wherein, R is selected from one of Cl, Br, and I.

[0042] A perovskite precursor solution refers to the chemical solution used to prepare perovskite thin films. This solution is one of the key materials in the manufacture of perovskite solar cells. In perovskite solar cells, the precursor solution typically contains the perovskite active material and solvent required to form the perovskite structure. The perovskite active material serves as the photoactive core, providing light absorption and carrier generation functions; the solvent dissolves the active material to form the precursor solution required for processing.

[0043] In order to optimize the performance of the perovskite film, an additive can be added to the precursor solution. The molecular structure of the additive in the embodiment of the present application contains a pyridine ring, a trifluoromethyl group and a halogen (-R). The single bond connected to the substituent runs through the corresponding ring, indicating that the substituent can be connected to any position of the ring, for example, -CF3 can be connected to any substitutable site of the pyridine ring; -R can be connected to any substitutable site of the pyridine ring.

[0044] This additive regulates the film formation process of the perovskite precursor solution in a high humidity environment through the synergistic effect of multiple functional groups within the molecule, constructing a synergistic mechanism to inhibit water penetration, regulate the crystallization process and passivate defects.

[0045] The trifluoromethylpyridine group in the additive forms a physical barrier on the perovskite surface through a strong hydrophobic effect, blocking water molecules from contacting the crystal lattice. The halogen atoms work synergistically with the nitrogen atoms of the pyridine ring to passivate uncoordinated lead defects in the perovskite through coordination bonding, reducing non-radiative recombination. The π-conjugated structure of the pyridine ring not only passivates defects but also maintains the continuity of the charge transfer channel, preventing carrier transport obstruction. The molecular design of the halogenated trifluoromethylpyridine enables it to combine hydrophobic protection, defect passivation, and crystallization regulation, thus enabling the preparation of highly crystalline, low-defect-density perovskite films in high-humidity environments.

[0046] In some embodiments, the additive includes at least one of 3-bromo-4-(trifluoromethyl)pyridine, 2-bromo-5-(trifluoromethyl)pyridine, 4-chloro-3-(trifluoromethyl)pyridine, 3-iodo-4-(trifluoromethyl)pyridine, and 4-bromo-3-(trifluoromethyl)pyridine.

[0047] The hydrophobic trifluoromethyl (-CF3) groups in these additive molecules tend to form a directional arrangement on the perovskite surface, thereby constructing a water-resistant barrier and reducing direct contact between water molecules and the perovskite lattice. At the same time, the halogen atoms and nitrogen atoms in these additive molecules can synergistically passivate defects in the perovskite film and inhibit non-radiative recombination, while the π-conjugated system helps maintain the smooth flow of charge transfer channels. Furthermore, the pyridine ring structure has a regulatory effect on the crystallization process, slowing the crystallization rate of the perovskite film and helping to form a dense, pinhole-free film.

[0048] The common feature of these compounds is the presence of halogen atoms and trifluoromethyl substituents on the pyridine ring: the strong hydrophobicity of the trifluoromethyl group can form a water-resistant layer at the perovskite grain boundary; the halogen atoms and the nitrogen atoms of the pyridine ring synergistically passivate the uncoordinated Pb 2+ defects, inhibiting non-radiative recombination. Among them, the differences between the three halogens, bromine, chlorine and iodine, are reflected in atomic size and electronegativity: bromine atoms have both moderate atomic radius and coordination ability, which is conducive to binding with the perovskite lattice; the large size of iodine atoms may enhance the steric effect, while the high electronegativity of chlorine atoms can enhance the electron capture ability. The design of different substitution sites (such as 3-bromine and 2-bromine) regulates the dipole moment distribution of the molecule and affects its directional arrangement on the perovskite surface. Selecting a combination of at least one compound can not only ensure the core functions of hydrophobic protection and defect passivation, but also provide flexibility for adjusting process parameters.

[0049] In some embodiments, the additive includes 4-bromo-3-(trifluoromethyl)pyridine.

[0050] This technical solution solves the problem of spatial coordination between the halogen substituent and the trifluoromethyl group on the pyridine ring by selecting a specific isomer of 4-bromo-3-(trifluoromethyl)pyridine as the additive. Specifically, the bromine atom is substituted at position 4 of the pyridine ring, forming an adjacent arrangement with the trifluoromethyl group at position 3. This spatial configuration allows the bromine atom to directly bind to the uncoordinated Pb in the perovskite lattice. 2+ The bromine substitution at position 4 can maximize the synergistic effect of the halogen passivation effect and the trifluoromethyl hydrophobic effect, while the trifluoromethyl substitution at position 3 ensures the stability of the directional arrangement of the molecules on the perovskite surface, thereby achieving stable film formation and further improvement of the performance of the perovskite film under high humidity conditions.

[0051] In some embodiments, the perovskite active material comprises an ABX3 compound, wherein A comprises at least one of a formamidinium ion, a methylamine ion, and a cesium ion; and B comprises Pb. 2+ 、Sn 2+ At least one of; X includes Cl - Br - , I - At least one of .

[0052] ABX3 compounds in perovskite active materials refer to a class of materials with a specific crystal structure known as the perovskite structure. In this chemical formula, A typically represents a larger organic or inorganic cation, located at the corners of the cubic unit cell; B typically represents a smaller metal cation, located at the body center of the cubic unit cell; and X represents an anion that forms a chemical bond with both A and B, typically oxygen (O), a halogen (such as chlorine Cl, bromine Br, or iodine I), and is located at the face center of the cubic unit cell.

[0053] This technical solution improves the stability and film quality of the precursor solution in high humidity environments from the perspective of material chemistry by limiting the composition of the perovskite active material. For the A-site ion selection of ABX3 compounds, formamidinium ion, methylamine ion and cesium ion have different ionic radii and coordination abilities, which can adjust the perovskite lattice stress and inhibit the phase transition induced by water molecules; Pb is selected for the B-site. 2+ or Sn 2+, using its strong bonding with halogens to reduce grain boundary defects caused by uncoordinated metal ions; the type of halogen at the X position directly affects the perovskite band gap and crystallization dynamics, through Cl - Br - , I - The combination can optimize the crystallization rate and avoid pinhole formation.

[0054] In some embodiments, the solvent includes dimethylformamide and N-methylpyrrolidone.

[0055] Regarding the limitation of solvents, compared with traditional solvents (such as DMF and DMSO) whose hygroscopicity causes the precursor solution to be easily deteriorated and the thin film crystallization to be uneven, the specific combination of dimethylformamide (DMF) and N-methylpyrrolidone (NMP) can synergistically regulate the viscosity and volatilization rate of the precursor solution, delay the film formation process, and promote orderly grain growth. At the same time, its polar characteristics help to uniformly disperse the additive molecules in the solution, thereby enhancing the hydrophobic protective layer and defect passivation effect.

[0056] In some embodiments, the concentration of the additive in the perovskite precursor solution is 0.1-10 mg / mL.

[0057] By limiting the concentration range of the additive, the stability of the solution system under high humidity conditions is further improved. The concentration range of the additive of 0.1 to 10 mg / mL enables it to form a hydrophobic protective layer in the solution while avoiding the obstruction of charge transfer caused by excessive addition. As an example, the concentration of the additive in the perovskite precursor solution can be 0.1 mg / mL, 1 mg / mL, 2 mg / mL, 4 mg / mL, 6 mg / mL, 8 mg / mL, 10 mg / mL and other typical but non-limiting values.

[0058] In some embodiments, the concentration of the ABX3 compound in the perovskite precursor solution is 0.6-2 mol / L.

[0059] This technical solution achieves the coordinated optimization of the quality stability of the film and the performance of the device in a high humidity environment by adjusting the composition parameters of the perovskite precursor solution. The concentration control of the ABX3 compound at 0.6-2 mol / L enables the precursor solution to have an appropriate viscosity, which not only allows for uniform spreading during film deposition, but also prevents grain boundary defects caused by excessively high concentrations that result in rapid crystallization. As an example, the concentration of the ABX3 compound in the perovskite precursor solution can be typical but non-limiting values ​​such as 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, and 2 mol / L.

[0060] In some embodiments, the volume ratio of dimethylformamide to N-methylpyrrolidone is 3:1 to 10:1.

[0061] This technical solution further constructs a stable solution system under high humidity conditions by limiting the solvent ratio range. The volume ratio of the solvent system of 3:1 to 10:1 is adjusted to balance the high solubility of dimethylformamide with the volatility of N-methylpyrrolidone, allowing the solution to achieve a controllable solvent evaporation process in humid air, thereby obtaining a dense perovskite film with an appropriate grain size. As an example, the volume ratio of dimethylformamide to N-methylpyrrolidone can be 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, and other typical but non-limiting values.

[0062] In summary, the coordinated limitation of the three parameters, additive concentration, ABX3 concentration, and solvent ratio, forms the key control window for the solution-to-film conversion process under a humidity environment, solving the problems of phase separation and defect proliferation caused by humidity sensitivity in traditional methods.

[0063] On the other hand, an embodiment of the present application provides a perovskite solar cell, comprising a transparent conductive substrate 1, a first transmission layer 2, a perovskite light absorption layer 3, a second transmission layer 4 and an electrode layer 5 stacked in sequence, wherein one of the first transmission layer 2 and the second transmission layer 4 is a hole transport layer, and the other is an electron transport layer; the perovskite light absorption layer 3 is prepared from the above-mentioned perovskite precursor solution under a humidity environment of 10% to 60% RH.

[0064] Figure 1 A schematic structural diagram of a perovskite solar cell according to an embodiment of the present application is shown, wherein the specific layers from bottom to top are: a transparent conductive substrate 1, a first transmission layer 2, a perovskite light absorption layer 3, a second transmission layer 4 and an electrode layer 5.

[0065] The present embodiment of the present invention achieves stable film formation by constructing a stacked structure including a perovskite light-absorbing layer and limiting the preparation of the light-absorbing layer to a relative humidity range of 10% to 60%. The transparent conductive substrate serves as the light incidence and charge collection interface, while the first and second transport layers are respectively selected from hole or electron transport materials to form a directional carrier transport path. The core of this method lies in controlling the humidity range during the preparation of the perovskite light-absorbing layer: in an environment of 10% to 60% RH, by adding halogenated trifluoromethylpyridine compounds to the precursor solution, the hydrophobic groups contained in them can form a water-resistant barrier on the perovskite surface; bromine atoms bind to uncoordinated lead ions, helping to reduce defects; and pyridine rings regulate crystallization dynamics through their coordination effect. The selection of this humidity range not only avoids the problem of uneven film layers caused by excessively rapid solvent volatilization under ultra-low humidity conditions, but also overcomes the limitation of traditional processes operating at humidity above 60% RH. This allows the light-absorbing layer to maintain its dense, pinhole-free properties even in higher humidity environments, thereby supporting efficient carrier transport and improving device stability. In this way, the present invention provides a new approach for fabricating high-performance perovskite solar cells under different humidity conditions, especially in high-humidity areas.

[0066] In some embodiments, the thickness of the perovskite light absorbing layer is 300-900 nm.

[0067] The thickness of the perovskite light-absorbing layer is controlled between 300 and 900 nanometers. This setting provides sufficient light-absorbing thickness to maintain a high short-circuit current while avoiding the lattice expansion and cracking problems caused by moisture penetration due to excessively thick layers. By precisely controlling the thickness within this range, the light absorption efficiency can be maximized while reducing the risk of material degradation due to moisture intrusion. This thickness selection helps maintain the structural stability and functional integrity of the perovskite layer, thereby supporting solar cells to achieve better photoelectric conversion performance. By adjusting the thickness within this range, the performance of the light-absorbing layer can be optimized according to specific application requirements, taking into account both light absorption and environmental tolerance. As an example, the thickness of the perovskite light-absorbing layer can be typical but non-limiting values ​​such as 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, and 900nm.

[0068] In some embodiments, the thickness of the first transmission layer is 10-400 nm.

[0069] The thickness of the first transport layer is set between 10 and 400 nanometers to balance the requirements of hole transport efficiency and interface recombination suppression. A thinner transport layer helps reduce series resistance and improve charge transfer rate; while an appropriately increased thickness enhances coverage and protection of the perovskite layer, reducing the impact of surface defects and the external environment on the internal material. By adjusting the thickness of this layer, the hole transport path can be optimized and the stability of the perovskite layer can be improved without sacrificing device performance, thereby supporting the overall performance of the solar cell. This design takes into account subtle variations in the function of the transport layer at different thicknesses, aiming to achieve optimal overall performance. As examples, the thickness of the first transport layer can be 10nm, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, etc., which are typical but non-limiting values.

[0070] In some embodiments, the second transmission layer has a thickness of 10 to 60 nm.

[0071] The thickness of the second transport layer is limited to between 10 and 60 nanometers. This design is intended to optimize the electron extraction process while avoiding the aggravation of carrier recombination caused by increased layer thickness. This thickness range is particularly suitable for the interface characteristics of perovskite films formed in high humidity environments, which helps to maintain good charge separation and transport performance without affecting the overall performance of the device due to excessive thickness of the transport layer. By fine-tuning the thickness of this layer, the properties of the perovskite light-absorbing layer can be better matched, thereby playing a positive role in improving the conversion efficiency of solar cells. As an example, the thickness of the second transport layer can be typical but non-limiting values ​​such as 10nm, 20nm, 30nm, 40nm, 50nm, and 60nm.

[0072] In some embodiments, the thickness of the electrode layer is 30-300 nm.

[0073] The thickness of the electrode layer is set between 30 and 300 nanometers. Such a thickness not only provides the necessary conductivity and mechanical strength, but also helps to control material consumption and cost. Within this range, the thickness parameters of the electrode layer are coordinated with the thermal expansion coefficient of the film under a humidity environment, reducing the risk of electrode peeling due to stress mismatch. By fine-tuning the thickness of this layer, the long-term stability of the device can be enhanced while maintaining good electrical performance, avoiding unnecessary material waste. This design takes into account the balance between conductivity, mechanical stability and cost, and aims to optimize the functional performance of the electrode layer and extend its service life in different working environments. As an example, the thickness of the electrode layer can be typical but non-limiting values ​​such as 30nm, 100nm, 150nm, 200nm, 250nm, 300nm, etc.

[0074] This application constructs a device structure system that is adapted to high-humidity film-forming conditions by precisely defining the coordinated range of thickness parameters of each functional layer.

[0075] In some embodiments, the material of the first transmission layer includes at least one of nickel oxide, a self-assembled monolayer, and PTAA.

[0076] Among them, nickel oxide refers to an inorganic hole transport material, which can be achieved by using a metal oxide layer prepared by magnetron sputtering or solution method. Its high conductivity forms a gradient match with the perovskite valence band energy level, reducing the hole extraction barrier. A self-assembled monolayer refers to a molecular layer that is formed by chemical bonding on the surface of a substrate. It can be achieved by using thiol or silane molecules to self-assemble on the surface of indium tin oxide, and the interface energy level arrangement is regulated by the molecular dipole effect. PTAA refers to a polytriarylamine organic polymer material, which can be prepared into a thin film by spin coating. Its high hole mobility and hydrophobic properties synergistically enhance the hole transport efficiency.

[0077] In some embodiments, the material of the second transmission layer is at least one of carbon 60 and (6,6)-phenyl-C61-butyric acid methyl ester.

[0078] Carbon-60 refers to a fullerene derivative with a three-dimensional conjugated structure, which can be formed using vacuum evaporation. It exhibits high electron mobility and an energy level that matches the perovskite conduction band. Methyl (6,6)-phenyl-C61-butyrate refers to a fullerene derivative with a phenyl side chain, which can be formed using solution spin coating. Its phenyl groups enhance intermolecular π-π stacking, forming an ordered electron transport network.

[0079] Specifically, when nickel oxide serves as an inorganic hole transport layer, its valence band position forms a stepped arrangement with the highest occupied molecular orbital energy level of the perovskite active layer. This energy difference drives the rapid migration of holes to the electrode, while the high stability of the metal oxide inhibits interfacial ion diffusion. The self-assembled monolayer, through the bonding of terminal functional groups with uncoordinated lead ions on the perovskite surface, passivates interfacial defects and reduces interfacial resistance. The PTAA polymer forms a dense structure during film formation, and its hydrophobic properties prevent the penetration of ambient water molecules into the perovskite layer. The three-dimensional conjugated structure of carbon 60 provides multidirectional electron transport pathways, and its lowest unoccupied molecular orbital energy level aligns with the perovskite conduction band energy level, promoting the rapid extraction of photogenerated electrons. The phenyl side chain of (6,6)-phenyl-C61-butyric acid methyl ester enhances film order through intermolecular π-π interactions, reducing electron scattering losses at grain boundaries.

[0080] Compared with existing technologies, traditional methods struggle to simultaneously meet energy level matching and interface stability requirements using a single transport layer material. For example, nickel oxide alone easily forms a Schottky barrier with the perovskite layer, while purely organic hole transport materials suffer from insufficient mobility. This approach achieves a balance between interface energy level control and carrier transport dynamics through a combination of inorganic and organic materials and structural optimization of fullerene derivatives.

[0081] Through the above technical solution, this application solves the interface recombination problem caused by the energy level mismatch between the transport layer material and the perovskite layer in an air preparation environment. The high conductivity of the inorganic material and the interface adaptability of the organic material synergistically reduce the carrier transport barrier. The ordered stacking structure of the fullerene derivative improves the electron mobility. The self-assembled monolayer passivates the interface defects, ultimately achieving efficient separation and transmission of electrons and holes.

[0082] On the other hand, an embodiment of the present application provides a method for preparing a perovskite solar cell, comprising the following steps: coating the above-mentioned perovskite precursor solution on a substrate in a humidity environment of 10% to 60% RH, and then annealing.

[0083] Among them, the perovskite precursor solution refers to a mixed solution containing a halogenated trifluoromethylpyridine additive (structure as shown in Chemical Formula I), which can be specifically achieved by a formula containing 4-bromo-3-(trifluoromethyl)pyridine. The additive inhibits the damage of water molecules to the perovskite lattice through hydrophobic groups and defect passivation mechanisms. Among them, the coating process refers to the film-forming operation carried out in an open environment, which can be specifically achieved by blade coating or slit coating. This step controls the uniformity of the film through the fluidity of the solution and adjusts the crystallization dynamics in conjunction with the humidity environment. Among them, annealing treatment refers to the process of promoting crystal growth by heating, which can be specifically implemented in the temperature range of 100 to 150°C. This process prompts the perovskite precursor to complete the phase transition and form a stable crystal structure.

[0084] Specifically, within the humidity control range, trifluoromethyl groups in the precursor solution preferentially adsorb at the grain boundaries, forming a hydrophobic barrier that blocks water penetration. At the same time, the binding of bromine atoms to uncoordinated lead ions reduces the surface defect state density. During the coating process, the coordination effect of the pyridine ring slows the rate of crystal nucleation, promoting the formation of a dense film. The thermal energy input during the annealing stage promotes complete evaporation of the solvent and repairs microcracks within the film, ultimately obtaining a photoactive layer with continuous grain boundaries.

[0085] In some specific embodiments, the coating operation can be performed using automatic spraying equipment in a ventilated environment, and a humidity sensor monitors environmental parameters in real time and feeds back to the control system.

[0086] Compared to existing methods, which rely on inert gas protection and strictly control humidity below 30% RH, this solution, through the synergistic effect of additives and process parameters, expands the film-forming humidity window to the range of conventional air environments. While passivating agents such as octadecyltrichlorosilane used in existing technologies require post-treatment, this solution integrates the additive directly into the precursor solution, streamlining the production process.

[0087] Through the above technical solution, this application achieves the direct preparation of high-quality perovskite light-absorbing layers in a conventional air environment, effectively suppressing moisture-induced phase separation and reducing the number of non-radiative recombination centers at grain boundaries. The film crystallinity is enhanced, and carrier mobility is significantly improved, thereby ensuring the stability of the photovoltaic performance of solar cells in non-humidity-controlled environments.

[0088] In some embodiments, the humidity environment is 40% to 60% RH.

[0089] Unlike existing technologies, where performance significantly degrades when humidity exceeds 40% RH, this solution breaks through the preparation limitations under high humidity conditions, enabling excellent device performance to be achieved in tropical and coastal areas (where the typical humidity range is 50%-60%). This adjustment not only overcomes the challenges encountered by traditional processes in high humidity environments, but also greatly enhances the industrial applicability of the technology. By preparing in this relatively high humidity environment, the need for expensive inert atmosphere protection can be reduced, production costs are reduced, and a more practical and economical option is provided for large-scale industrial production. In addition, this method also adapts to the needs of a wider range of geographical areas, especially in places with naturally high humidity, further expanding its application potential.

[0090] In some embodiments, the coating method includes at least one of blade coating, slit coating, spray coating, and evaporation.

[0091] Coating refers to the process of transferring the perovskite precursor solution to the substrate surface. Specifically, this can be achieved by controlling the wet film thickness through blade speed and gap adjustment using a doctor blade, or by uniformly spreading the solution through a precision pumping system using a slot coating method. These methods maintain a directional distribution of the additive during film formation. When using doctor blade or slot coating, the shear force of the solution promotes coordination between the pyridine ring and the perovskite precursor, thereby slowing the crystallization kinetics and forming a dense film free of pinhole defects.

[0092] In some embodiments, the annealing temperature is 100-150°C.

[0093] The annealing temperature refers to the heat treatment range during the film drying and crystallization phase. Specifically, a gradient temperature ramp can be used to heat the substrate to 100-150°C. This temperature range promotes the orderly growth of perovskite grains while preventing thermal decomposition of additive molecules that could lead to passivation layer failure. When the annealing stage is performed within the 100-150°C range, the solvent molecules can fully evaporate while maintaining the bond strength between the additive and the perovskite crystal surface, thus achieving structural stability in the passivation layer at high temperatures.

[0094] like Figure 2 As shown, the preparation of perovskite solar cells mainly includes the following steps:

[0095] S1: Pretreatment of transparent conductive substrate:

[0096] FTO (fluorine-doped tin oxide) or ITO (indium tin oxide) conductive glass can be used as the substrate. Ultrasonic cleaning is performed using detergents and / or organic solvents, followed by nitrogen drying and UV or ozone treatment to remove organic residues.

[0097] S2: Depositing the first transport layer (taking the hole transport layer as an example):

[0098] The nickel oxide precursor solution is spin-coated on the substrate and annealed to form a dense layer; the SAMs material (self-assembled monolayer material) is prepared into an ethanol solution (concentration 0.8-1 mg / mL); the solution is spin-coated and annealed to form a hole transport layer;

[0099] S3: Deposition of perovskite light absorbing layer:

[0100] In a humidity environment of 10-60% RH, the aforementioned perovskite precursor solution is applied to the first transport layer and annealed;

[0101] S4: Depositing the second transport layer (taking the electron transport layer as an example):

[0102] Using vacuum evaporation process, C 60 layer; can be in C 60 A BCP (bathocuproin) layer is deposited on the layer;

[0103] S5: Preparation of electrode layer: silver electrode deposition.

[0104] The following describes the details in conjunction with specific embodiments.

[0105] Example 1

[0106] Cs based on glass / FTO / nickel oxide / Me-4PACz / doped 4-bromo-3-(trifluoromethyl)pyridine 0.1 FA 0.9 PbI3 perovskite / C 60The preparation process of perovskite solar cells with a / BCP / Ag device structure is as follows:

[0107] Step 1: Immerse FTO conductive glass (15Ω / sq) in detergent, deionized water, ethanol, and isopropanol, sequentially, and ultrasonically clean for 15 minutes each. After cleaning, dry the surface under nitrogen and treat with UV / ozone for 25 minutes to remove organic residues.

[0108] Step 2: The nickel oxide precursor solution was spin-coated on the pretreated FTO substrate at 3000 rpm for 30 seconds, and then annealed on a hot plate at 150° C. for half an hour to form a dense nickel oxide layer with a thickness of about 30 nm.

[0109] Step 3: Prepare the SAMs material Me-4PACz ([4-(9H-carbazol-9-yl)butyl]phosphonic acid methyl derivative) into a 1 mg / mL ethanol solution and spin-coat it on the nickel oxide layer at 5000 rpm for 30 seconds. Then anneal it on a hot plate at 100°C for ten minutes to form a self-assembled monolayer with a thickness of about 3 nm.

[0110] Step 4: PbI2, FAI, CsI and 4-bromo-3-(trifluoromethyl)pyridine (concentration of 2.0 mg / mL) were dissolved in a DMF / NMP mixed solvent (volume ratio 7:1) and stirred for 2 hours to obtain 1.5 mol / L CsI. 0.1 FA 0.9 PbI3 precursor solution.

[0111] Step 5: Take 15 μL of the perovskite precursor solution obtained in step 4 and prepare a perovskite film by blade coating at an air humidity of 60% at a blade coating speed of 6 mm / s, followed by annealing on a hot plate at 130° C. for 30 minutes.

[0112] Step 6: C with purity >99% 60 The powder is deposited on the surface of the perovskite layer by vacuum evaporation process with a thickness of 20nm and a deposition rate of Vacuum degree ≤5×10 -4 Pa.

[0113] Step 7: BCP (bathocuproine) is deposited on C by vacuum evaporation process. 60 layer surface, thickness is 8nm, deposition rate Vacuum degree ≤5×10 -4 Pa.

[0114] Step 8: Deposit a 100nm silver electrode on the BCP layer using vacuum evaporation at a rate of The patterned mask defines an effective area of ​​0.6 cm 2.

[0115] Example 2

[0116] Cs based on glass / FTO / nickel oxide / 2PACz / doped 4-bromo-3-(trifluoromethyl)pyridine 0.05 FA 0.95 PbI3 perovskite / C 60 The preparation process of perovskite solar cells with a / BCP / Ag device structure is as follows:

[0117] Step 1: Immerse FTO conductive glass (15Ω / sq) in detergent, deionized water, ethanol, and isopropanol, sequentially, and ultrasonically clean for 15 minutes each. After cleaning, dry the surface under nitrogen and treat with UV / ozone for 25 minutes to remove organic residues.

[0118] Step 2: The nickel oxide precursor solution was spin-coated on the pretreated FTO substrate at 3000 rpm for 30 seconds, and then annealed on a hot plate at 150° C. for half an hour to form a dense nickel oxide layer with a thickness of about 30 nm.

[0119] Step 3: Prepare the SAMS material 2PACz into a 0.8 mg / mL ethanol solution and spin-coat it on the nickel oxide layer at 5000 rpm for 30 seconds. Then anneal it on a hot plate at 100°C for ten minutes to form a self-assembled monolayer with a thickness of about 3 nm.

[0120] Step 4: PbI2, FAI, CsI and 4-bromo-3-(trifluoromethyl)pyridine (concentration of 2.0 mg / mL) were dissolved in a DMF / NMP mixed solvent (volume ratio 6:1) and stirred for 2 hours to obtain 1.5 mol / L CsI. 0.05 FA 0.95 PbI3 precursor solution.

[0121] Step 5: Take 15 μL of the perovskite precursor solution obtained in step 4 and prepare a perovskite film by blade coating at an air humidity of 60% at a blade coating speed of 8 mm / s, followed by annealing on a hot plate at 130° C. for 30 minutes.

[0122] Step 6: C with purity >99% 60 The powder is deposited on the surface of the perovskite layer by vacuum evaporation process with a thickness of 20nm and a deposition rate of Vacuum degree ≤5×10 -4 Pa.

[0123] Step 7: BCP (bathocuproine) is deposited on C by vacuum evaporation process. 60 layer surface, thickness is 8nm, deposition rate Vacuum degree ≤5×10 -4Pa.

[0124] Step 8: Deposit a 100nm silver electrode on the BCP layer using vacuum evaporation at a rate of The patterned mask defines an effective area of ​​0.6 cm 2 .

[0125] Example 3

[0126] Cs based on glass / FTO / nickel oxide / Me-4PACz / doped 4-bromo-3-(trifluoromethyl)pyridine 0.1 FA 0.9 PbI3 perovskite / C 60 Preparation of perovskite solar cells with a / BCP / Ag device structure. The difference between Example 3 and Example 1 is that in step 4, the concentration of 4-bromo-3-(trifluoromethyl)pyridine added to the perovskite precursor solution is 0.5 mg / mL, and the other operations are the same as in Example 1.

[0127] Example 4

[0128] Cs based on glass / FTO / nickel oxide / Me-4PACz / doped 4-bromo-3-(trifluoromethyl)pyridine 0.1 FA 0.9 PbI3 perovskite / C 60 Preparation of perovskite solar cells with a / BCP / Ag device structure. The difference between Example 4 and Example 1 is that in step 4, the concentration of 4-bromo-3-(trifluoromethyl)pyridine added to the perovskite precursor solution is 1 mg / mL, and the other operations are the same as in Example 1.

[0129] Example 5

[0130] Cs based on glass / FTO / nickel oxide / Me-4PACz / doped 4-bromo-3-(trifluoromethyl)pyridine 0.1 FA 0.9 PbI3 perovskite / C 60 Preparation of perovskite solar cells with a / BCP / Ag device structure. The difference between Example 5 and Example 1 is that in step 4, the concentration of 4-bromo-3-(trifluoromethyl)pyridine added to the perovskite precursor solution is 3 mg / mL, and the other operations are the same as in Example 1.

[0131] Example 6

[0132] Cs based on glass / FTO / nickel oxide / Me-4PACz / doped 4-bromo-3-(trifluoromethyl)pyridine 0.1 FA 0.9 PbI3 perovskite / C 60Preparation of perovskite solar cells with a / BCP / Ag device structure. The difference between Example 6 and Example 1 is that in step 4, the concentration of 4-bromo-3-(trifluoromethyl)pyridine added to the perovskite precursor solution is changed to 4 mg / mL, and the other operations are the same as in Example 1.

[0133] Example 7

[0134] Cs based on glass / FTO / nickel oxide / Me-4PACz / doped 3-iodo-4-(trifluoromethyl)pyridine 0.1 FA 0.9 PbI3 perovskite / C 60 Preparation of perovskite solar cells with a / BCP / Ag device structure. The difference between Example 7 and Example 1 is that in step 4, 3-iodine-4-(trifluoromethyl)pyridine is used as the additive in the perovskite precursor solution, and the other operations are the same as in Example 1.

[0135] Example 8

[0136] Cs based on glass / FTO / nickel oxide / Me-4PACz / doped 2-bromo-5-(trifluoromethyl)pyridine 0.1 FA 0.9 PbI3 perovskite / C 60 Preparation of perovskite solar cells with a / BCP / Ag device structure. The difference between Example 8 and Example 1 is that in step 4, 2-bromo-5-(trifluoromethyl)pyridine is used as the additive in the perovskite precursor solution, and other operations are the same as in Example 1.

[0137] Example 9

[0138] Cs based on glass / FTO / nickel oxide / Me-4PACz / doped 4-chloro-3-(trifluoromethyl)pyridine 0.1 FA 0.9 PbI3 perovskite / C 60 Preparation of perovskite solar cells with a / BCP / Ag device structure. The difference between Example 9 and Example 1 is that in step 4, 4-chloro-3-(trifluoromethyl)pyridine is used as the additive in the perovskite precursor solution, and the other operations are the same as in Example 1.

[0139] Comparative Example 1

[0140] The difference between Comparative Example 1 and Example 1 is that no 4-bromo-3-(trifluoromethyl)pyridine is added to the perovskite precursor solution.

[0141] Comparative Example 2

[0142] The difference between Comparative Example 2 and Example 2 is that no 4-bromo-3-(trifluoromethyl)pyridine is added to the perovskite precursor solution.

[0143] Performance Testing

[0144] In order to verify the progress of the examples of the present application, the samples of the examples and comparative examples were tested as follows:

[0145] 1. Photoelectric performance test

[0146] The test light intensity is AM 1.5G (1000W / m 2 ) were used to test the photoelectric performance of the perovskite solar cells prepared in the examples and comparative examples using a xenon lamp solar simulator.

[0147] 2. XRD test

[0148] The perovskite light absorbing layer was tested by XRD.

[0149] Performance Results

[0150] The test light intensity is AM 1.5G (1000W / m 2 ) xenon lamp solar simulator was used to test the photoelectric performance of the perovskite solar cells prepared in Example 1 and Comparative Example 1. The JV curves and performance parameters of the devices are shown in FIG. Figure 3 The corresponding device parameters are summarized in Table 1.

[0151] Table 1 Device parameters of Example 1 and Comparative Example 1

[0152]

[0153] The power conversion efficiency (PCE) of the device in Example 1 is 20.737%, the open circuit voltage (Voc) is 1.092 V, and the short circuit current density (Jsc) is 24.590 mA / cm 2 , FF is 77.224%. In comparison, the PCE of the device in Comparative Example 1 is 19.633%, Voc is 1.051V, and Jsc is 24.236mA / cm 2 , FF is 77.082%. The photoelectric conversion efficiency of Example 1 is significantly better than that of Comparative Example 1, which shows that under 60% RH air humidity, doping with 4-bromo-3-(trifluoromethyl)pyridine can effectively improve device performance.

[0154] Figure 4 Figure 2 is the XRD spectrum of the perovskite film of Example 1 and Comparative Example 1. Compared with the XRD spectrum of the perovskite film of Comparative Example 1, the (100) peak intensity of the former is significantly enhanced, indicating that the crystallinity of the perovskite film is improved after doping with 4-bromo-3-(trifluoromethyl)pyridine.

[0155] The test light intensity is AM 1.5G (1000W / m 2) xenon lamp solar simulator was used to test the photoelectric performance of the perovskite solar cells prepared in Example 2 and Comparative Example 2. The JV curves and performance parameters of the devices are shown in FIG. Figure 5 The corresponding device parameters are summarized in Table 2.

[0156] Table 2 Device parameters of Example 2 and Comparative Example 2

[0157]

[0158] The power conversion efficiency (PCE) of the device in Example 2 is 20.351%, the open circuit voltage (Voc) is 1.042 V, and the short circuit current density (Jsc) is 24.520 mA / cm 2 , FF is 79.689%. In comparison, the PCE of the device in comparative example 2 is 18.967%, Voc is 1.045V, and Jsc is 24.960mA / cm 2 , FF is 79.036%. The photoelectric conversion efficiency of Example 2 is significantly better than that of Comparative Example 2, which shows that under 60% RH air humidity, doping with 4-bromo-3-(trifluoromethyl)pyridine can effectively improve device performance.

[0159] Table 3 is a comparison of the performance of the perovskite solar cells obtained in Examples 1 to 9 and Comparative Examples 1 to 2

[0160]

[0161] The data in Table 3 show that at 60% RH, doping with 2 mg / mL of 4-bromo-3-(trifluoromethyl)pyridine can better improve device performance.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A perovskite precursor solution, characterized in that It includes perovskite active materials, additives and solvents; the molecular structure of the additive is shown in Formula I: Wherein, R is selected from one of Cl, Br, and I.

2. The perovskite precursor solution according to claim 1, characterized in that The additive includes at least one of 3-bromo-4-(trifluoromethyl)pyridine, 2-bromo-5-(trifluoromethyl)pyridine, 4-chloro-3-(trifluoromethyl)pyridine, 3-iodo-4-(trifluoromethyl)pyridine, and 4-bromo-3-(trifluoromethyl)pyridine.

3. The perovskite precursor solution according to claim 2, characterized in that The additive includes 4-bromo-3-(trifluoromethyl)pyridine.

4. The perovskite precursor solution according to any one of claims 1 to 3, characterized in that The perovskite active material includes an ABX3 compound, wherein A includes at least one of formamidinium ions, methylamine ions, and cesium ions; B includes Pb 2 + 、Sn 2+ At least one of; X includes Cl - Br - , I - At least one of; And / or, the solvent includes dimethylformamide and N-methylpyrrolidone.

5. The perovskite precursor solution according to any one of claims 1 to 4, characterized in that The concentration of the additive in the perovskite precursor solution is 0.1 to 10 mg / mL; and / or, the concentration of the ABX3 compound in the perovskite precursor solution is 0.6-2 mol / L; And / or, the volume ratio of the dimethylformamide to the N-methylpyrrolidone is 3:1 to 10:

1.

6. A perovskite solar cell, characterized in that: It comprises a transparent conductive substrate, a first transport layer, a perovskite light-absorbing layer, a second transport layer and an electrode layer stacked in sequence, wherein one of the first transport layer and the second transport layer is a hole transport layer, and the other is an electron transport layer; the perovskite light-absorbing layer is prepared by the perovskite precursor solution according to any one of claims 1 to 5 under a humidity environment of 10% to 60% RH.

7. The perovskite solar cell according to claim 6, characterized in that The thickness of the perovskite light absorbing layer is 300 to 900 nm; and / or, the thickness of the first transmission layer is 10 to 400 nm; and / or, the thickness of the second transmission layer is 10 to 60 nm; And / or, the thickness of the electrode layer is 30 to 300 nm.

8. The perovskite solar cell according to claim 6 or 7, characterized in that The material of the first transmission layer includes at least one of nickel oxide, self-assembled monolayer, and PTAA; And / or, the material of the second transmission layer is at least one of carbon 60 and (6,6)-phenyl-C61-butyric acid methyl ester.

9. A method for preparing a perovskite solar cell, characterized in that: The following steps are involved: In a humidity environment of 10% to 60% RH, the perovskite precursor solution according to any one of claims 1 to 5 is coated on a substrate, and then annealed.

10. The method for preparing a perovskite solar cell according to claim 9, wherein: The humidity environment is 40% to 60% RH; and / or, the coating method includes at least one of blade coating, slit coating, spray coating, and vapor deposition; And / or, the annealing treatment temperature is 100-150°C.

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