Method for producing a hole transport layer, solar cell and photovoltaic module

Abstract

The application relates to the technical field of solar cells, in particular to a preparation method of a hole transport layer, a solar cell and a photovoltaic module. The preparation method of the solar cell of the application comprises the following steps: preparing a wet film comprising a single-molecule self-assembly material; applying external force to disturb the wet film, so that a shear force field is generated in the wet film, so as to promote the spreading of the single-molecule self-assembly material in the wet film; and curing the wet film to form at least a part of the hole transport layer. According to the first aspect of the application, the external force is applied to disturb the wet film, so that the shear force field is generated in the wet film, the accumulation or loss of the SAMs material can be reduced, the film uniformity is improved, and then the crystallization quality of the perovskite layer can be improved, and the device efficiency and stability are improved.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a method for preparing a hole transport layer, a solar cell, and a photovoltaic module. Background Technology

[0002] Perovskite solar cells (PSCs), as a representative of third-generation photovoltaic technology, have become a research hotspot due to their excellent photoelectric performance, high photoelectric conversion efficiency, low cost of low-temperature solution preparation, and simple process.

[0003] Currently, perovskite solar cells are mainly classified into two structures: nip and pin. The nip structure typically consists of an electron transport layer (ETL), a perovskite light-absorbing layer, a hole transport layer (HTL), and a back electrode. The pin structure generally stacks the HTL, perovskite light-absorbing layer, electron transport layer (ETL), and back electrode in that order. The pin structure has attracted much attention due to its excellent device stability, especially with the introduction of self-assembled monolayers (SAMs), which further improves the photoelectric conversion efficiency of this type of cell and makes it the mainstream technology for mass production. In the fabrication of small-area perovskite devices, spin coating provides a shear field to the precursor solution, which helps form a continuous and uniform film, resulting in a high-quality film. However, this process is difficult to apply to large-area production; currently, large-area fabrication mainly relies on slot coating technology. However, the lack of an effective shear field during slot coating can easily lead to a decrease in film quality, especially affecting the SAMs layer. In theory, SAMs need to form a uniform and dense monolayer. However, slit coating often causes local SAMs to be missing or accumulated, resulting in uneven film, which in turn affects the crystal quality of the perovskite layer, ultimately leading to a decrease in device efficiency and stability.

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

[0005] This application provides a method for preparing a hole transport layer, a solar cell, and a photovoltaic module to solve or alleviate one or more of the technical problems mentioned above.

[0006] The first aspect of this application provides a method for preparing a solar cell, comprising:

[0007] Preparation of wet films including single-molecule self-assembled materials; An external force is applied to disturb the wet film, causing a shear force field to be generated within the wet film, thereby promoting the spread of the single-molecule self-assembled material within the wet film; The wet film is cured to form at least a partial hole transport layer.

[0008] In a first aspect of this application, an external force is applied to the wet film to generate a shear force field within the wet film, which can reduce the accumulation or absence of SAMs materials, improve film uniformity, and thereby improve the crystal quality of the perovskite layer, thereby enhancing device efficiency and stability.

[0009] The second aspect of this application provides a solar cell fabricated according to the method described in this application. Thanks to the ultra-high macroscopic uniformity and highly ordered molecular arrangement of the SAMs (hole transport layers), a near-perfect interfacial contact is formed between the SAMs and the perovskite light-absorbing layer. This effectively reduces the energy barrier and defect state density at the interface, thereby significantly improving charge extraction efficiency and reducing non-radiative recombination losses. This cell not only has higher photoelectric conversion efficiency (higher Voc, FF), but also exhibits excellent performance distribution across the entire cell when fabricated over a large area, effectively avoiding overall performance loss caused by local "weaknesses." This is crucial for manufacturing high-efficiency, high-reliability photovoltaic modules.

[0010] A third aspect of this application provides a photovoltaic module, which includes the solar cell of the second aspect of this application. Thus, by integrating a solar cell with intrinsically high performance and high reliability, it not only possesses higher initial efficiency at the time of manufacture but also exhibits superior power retention and durability throughout its entire life cycle, providing core technological support for the long-term reduction of the levelized cost of electricity (LCOE) of photovoltaic power plants. Attached Figure Description

[0011] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0012] Figure 1 This is a schematic diagram of the structure of the perovskite solar cell provided in the embodiments of this application.

[0013] Explanation of reference numerals in the attached figures: 1 is glass; 2 is the front electrode layer; 3 is the first charge transport layer; 4 is the perovskite light-absorbing layer; 5 is the second charge transport layer; 6 is the back electrode layer; 7 is the first scribe line (P1 scribe line); 8 is the second scribe line (P2 scribe line); 9 is the third scribe line (P3 scribe line); 10 is the lead wire. Detailed Implementation

[0014] The embodiments of this application are described in detail below, examples of which are illustrated in the accompanying drawings. In the drawings, for clarity, the dimensions of layers, regions, and elements, as well as their relative dimensions, may be exaggerated. Throughout, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0015] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this application.

[0016] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0017] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0018] In this application, when numerical intervals (i.e., numerical ranges) are involved, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0019] To address the aforementioned issues, this application proposes an improved fabrication method to meet the shear force field requirements during the slot coating process of SAMs layers. After the wet SAMs film is coated in the slots, a soft-blade process is added to apply a controllable shear force field, thereby improving the uniformity and coverage of the wet film. This method is simple and particularly suitable for the fabrication of large-area perovskite solar cells. It improves device efficiency and stability while facilitating their commercial mass production.

[0020] The following provides a definition of the terminology used in this application.

[0021] The embodiments of this application can employ specific external process methods (e.g., applying contact pressure) to achieve the active application and precise control of this internal shear force field.

[0022] This application provides a method for fabricating a hole transport layer, as well as a technical solution for solar cells and photovoltaic modules. Based on this, the formation of SAMs layers over large areas becomes more uniform. See below for details.

[0023] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. It should be understood that these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0024] This application provides a method for fabricating a hole transport layer. The method for fabricating the hole transport layer may include the following steps: S1. Preparation of a wet film comprising single-molecule self-assembled materials; Alternatively, the wet film can be prepared by slot coating, blade coating, or spray coating. All of these methods can form a wet film.

[0025] Optionally, the concentration of the self-assembled monomolecule material in the solution used to form the wet film can be from 0.1 mg / mL to 10 mg / mL. This is beneficial for forming a complete and dense monolayer. For example, the concentrations can be 0.1 mg / mL, 1 mg / mL, 2 mg / mL, 4 mg / mL, 6 mg / mL, 8 mg / mL, 10 mg / mL, etc.

[0026] Optionally, the initial thickness can range from 1 μm to 100 μm. The initial thickness refers to the initial wet film thickness after coating and before any processing. This thickness range ensures that the wet film has sufficient flowability to respond to shear forces, while avoiding defects in the film layer after drying due to excessive thickness.

[0027] Currently, large-area fabrication of SAMs layers relies on slot coating technology. Theoretically, SAMs should form a uniform and dense monolayer, but slot coating technology often causes localized SAMs deficiency or accumulation, resulting in uneven SAMs layers and consequently affecting the crystal quality of the perovskite light-absorbing layer.

[0028] S2. Apply external force to disturb the wet film, so as to promote the spread of monomolecular self-assembled materials within the wet film.

[0029] Therefore, in step S2, applying an external force to disturb the wet film generates a shear force field within the wet film, which can reduce the accumulation or absence of SAMs materials and improve the uniformity of film formation.

[0030] It is worth noting that the "shear force field" in the embodiments of this application refers to a shear force field formed and maintained inside the wet film of the single-molecule self-assembled material. This shear force field acts directly on the single-molecule self-assembled material in the wet film, and its core physical effects are: (1) inducing the molecules of the single-molecule self-assembled material to oriented and form a more ordered monolayer structure; (2) promoting the uniform spreading of the wet film as a whole, eliminating local accumulation or missing parts, and improving the continuity of the film layer; (3) driving the solution to fill the micro-depression structure on the surface of the substrate (such as grooves formed by laser scribing).

[0031] In the embodiments of this application, the external force can be electric field force, magnetic force, contact mechanical force, or any force that can generate a shear force field within the wet film to promote the uniform spreading of single-molecule self-assembled materials within the wet film.

[0032] In the embodiments of this application, the disturbed wet film is in a state where the solvent has not significantly evaporated and has sufficient fluidity.

[0033] In some embodiments, this application employs a doctor blade to coat the wet film; the doctor blade has a Shore hardness of 20A to 90A. Thus, by moving the relatively soft doctor blade within the wet film, the doctor blade can generate contact pressure with the substrate supporting the wet film, thereby compressing and shearing the wet film, generating a shear force field within the wet film, which promotes the oriented alignment and uniform spreading of the single-molecule self-assembled materials, and prevents mechanical damage. This method is a controllable contact perturbation to precisely regulate the film formation process of SAMs.

[0034] Furthermore, the scraper is made of an elastomeric material with corresponding hardness. For example, the scraper material can be at least one of polyurethane, silicone rubber, and fluororubber.

[0035] Furthermore, the contact pressure generated can be controlled by controlling the cutting depth of the scraper, thereby controlling the formation and maintenance of the shear force field within the wet film.

[0036] Optionally, in this embodiment, the contact pressure is controlled between 0.1 kPa and 10 kPa. Below this range, it is difficult to effectively improve film uniformity; above this range, it may damage the film on the substrate.

[0037] For example, the contact pressure can be 0.1 kPa, 1 kPa, 2 kPa, 4 kPa, 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa, 10 kPa, etc.

[0038] It should be noted that "contact pressure" refers to the normal force exerted by the squeegee perpendicularly on a unit area of ​​the wet film. It determines the tightness of the adhesion between the squeegee and the substrate / wet film. In the embodiments of this application, the contact pressure of the squeegee can be indirectly controlled by the calibrated squeegee cutting depth.

[0039] Furthermore, the testing and calibration of contact pressure can be performed as follows: Using a laser displacement sensor or a high-precision vision system, the displacement (i.e., cutting depth) of the blade relative to the substrate reference plane is measured in real time during static pressing and movement. A precision force gauge is used to measure the normal force exerted by the blade on the substrate at different cutting depths. Simultaneously, the contact area between the blade and the substrate is measured (estimated through the imprint method or theoretical calculation based on blade deformation). Using the formula pressure = normal force / contact area, the contact pressure corresponding to different cutting depths is calculated, thus establishing a "cutting depth - contact pressure" calibration curve.

[0040] Optionally, the angle between the blade of the scraper and the surface of the wet film is 10° to 60°. This angle range ensures that the shear force field can be effectively applied, and avoids problems such as the wet film being scraped or the substrate being scratched due to an angle that is too large (>60°), or insufficient disturbance and weak treatment effect due to an angle that is too small (<10°).

[0041] In some embodiments, when preparing a wet film using slit coating, a doctor blade is positioned behind the coating head that forms the wet film comprising a self-assembled monomolecular material in the coating direction. The distance between the doctor blade and the coating head can be 1 cm to 20 cm. At this distance, the wet film treated by the doctor blade is in a "liquid-dominated period"—a stage where the solvent has not yet largely evaporated and the viscosity has not changed significantly. Applying shear force to the wet film at this time maximizes the driving of molecular rearrangement and solution flow with minimal energy consumption, thereby most effectively improving film uniformity. For example, the distance between the doctor blade and the coating head can be 1 cm, 5 cm, 8 cm, 15 cm, 18 cm, 20 cm, etc.

[0042] Furthermore, the doctor blade's movement speed can be kept consistent with that of the coating head. This allows for simultaneous homogenization during coating completion.

[0043] In other embodiments, the method for preparing the hole transport layer involves preparing a wet film on a substrate; wherein the substrate includes a transparent conductive layer, or the substrate includes a transparent conductive layer and a first hole transport layer located on the transparent conductive layer; and the transparent conductive layer is provided with a P1 scribe line.

[0044] In the fabrication of perovskite modules (or sub-cell series modules), P1 scribing is the first laser scribing step. Its purpose is to etch mutually insulating trenches into a transparent conductive oxide layer (such as ITO or FTO), thereby dividing the large-area conductive substrate into multiple series-connected sub-cell regions. SAMs (self-assembled monolayers) are typically deposited on the substrate after P1 scribing using extremely dilute ethanol solutions through methods such as slot coating. Accumulation mainly stems from the following two physical effects: "Trench effect": The P1 scribing is a micro-trench (typically 20-50 micrometers wide and several hundred nanometers deep). When the SAM solution is coated on it, the hydrodynamic behavior of the wet film differs between flat areas and trenches. The trench acts like a tiny "reservoir," where the solution easily flows in and is retained due to capillary action. "Coffee ring effect": During the drying process of the wet film, the solvent evaporates faster from the edges. Because the edge of the P1 trench (i.e., the trench wall) has a large curvature, it will intensify the local evaporation of the solvent, driving the dissolved SAMs molecules to migrate and deposit towards the trench edge, resulting in an excessively high local concentration of SAMs at the trench edge, forming an accumulation. In summary, the accumulation of molecules towards the trench edge when the solution flows into the trench and during drying will lead to excessive accumulation of SAMs material at the P1 scribe line.

[0045] In some embodiments, applying external force includes: using a doctor blade to coat the wet film to generate a shear force field within the wet film, thereby promoting the uniform spreading of monomolecular self-assembled materials within the wet film; simultaneously, using the doctor blade to coat the monomolecular self-assembled material in the area marked with the first scribing and on both sides to achieve uniform distribution. This achieves the following functions: inducing a shear force field within the wet film to promote the directional arrangement of monomolecular self-assembled material molecules and the uniform spreading of the wet film as a whole; simultaneously, the elastic deformation and shearing action of the doctor blade can intervene in the monomolecular self-assembled material accumulated in the P1 scribing area and on both sides to eliminate localized excessive accumulation and ensure the continuity of the film layer in this area.

[0046] S3. Curing the wet film to form at least a partial hole transport layer.

[0047] Optionally, the SAMs layer can function as a hole transport layer on its own, or it can be combined with other hole transport material functional layers to form a hole transport layer.

[0048] For example, SAMs layers can be combined with NiO. x These layers together form the hole transport layer.

[0049] Optionally, the SAMs material can be at least one of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACZ), (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid (MeO-2PACZ), (4-(3,6-dimethyl-9H-carbazole-9-yl)ethyl)phosphonic acid (Me-4PACZ), (2-(4-(bis(4-methoxyphenyl)amino)phenyl)-1-cyanotitanium)phosphonic acid (MPA-CPA), (4-(2,7-dibromo-9,9-dimethylacridin-10(9H)yl)butyl)phosphonic acid (DMAcPA), and [4-(3,6-diphenyl-9H-carbazole-9-yl)butyl]phosphonic acid (Ph-4PACZ).

[0050] The second aspect of this application provides a solar cell fabricated according to the method described in this application. Thanks to the ultra-high uniformity of SAMs (hole transport layers) on a macroscopic scale and the highly ordered molecular arrangement on a microscopic scale, it forms a near-perfect interfacial contact with the perovskite light-absorbing layer. This effectively reduces the energy barrier and defect state density at the interface, thereby significantly improving charge extraction efficiency and reducing non-radiative recombination losses. The method eliminates "weak points" and "abnormal crystallization regions" caused by SAM accumulation or absence in key areas such as P1 laser scribing during solar cell fabrication. This results in a highly consistent, defect-free layered structure throughout the entire cell, especially in the isolation region of the tandem sub-cells, fundamentally suppressing the chain degradation reaction caused by local defects under working stress (light, heat, electricity), and significantly improving the long-term operational stability and lifespan of the device. This cell not only has higher photoelectric conversion efficiency (higher Voc, FF), but also exhibits excellent performance distribution across the entire cell during large-area fabrication, effectively avoiding overall performance loss caused by local "shortcomings," which is crucial for manufacturing high-efficiency, high-reliability photovoltaic modules.

[0051] In some embodiments, the solar cell is a perovskite solar cell, which may consist of multiple sub-cells, such as 55, connected in series. (See reference...) Figure 1 The perovskite solar cell shown in the figure is fabricated using the following steps: S1. Base preparation and graphical representation: A glass substrate 1 is provided, on which an FTO thin film is deposited as a front electrode layer 2. A first laser scribing is performed on the front electrode layer 2 to form equally spaced P1 scribing lines 7, dividing the front electrode layer into multiple electrically insulated strip electrodes.

[0052] S2. Fabrication of the first charge transport layer 3: On the FTO front electrode layer 2 with P1 markings, NiO was first deposited using magnetron sputtering. xLayer. Subsequently, a self-assembled monolayer was prepared using the homogenization method of this application. x The layer and the SAMs layer together constitute the first charge transport layer 3, which specifically includes: S201, Wet film coating: The slit coating method is used to coat the NiO film as described above. x A SAMs solution is coated onto the layer to form a continuous wet film with an initial thickness of approximately 1 μm to 100 μm; the concentration of the SAMs solution is 0.1 mg / mL to 10 mg / mL.

[0053] S202, Homogenization Treatment: A doctor blade made of silicone rubber is placed approximately 1 cm to 20 cm behind the coating head. The doctor blade's movement speed is controlled to match the linear velocity of the slot coating. By adjusting the doctor blade's cutting depth and maintaining an angle of approximately 10° to 60° between its blade and the wet film surface, a contact pressure of approximately 0.1 kPa to 10 kPa is generated between the doctor blade and the substrate carrying the wet film.

[0054] The scraping operation of the doctor blade creates a controllable shear force field inside the wet film, which effectively promotes the directional arrangement of SAMs molecules and the uniform spread of the solution, thereby obtaining a highly uniform and continuous first charge transport layer 3.

[0055] S203, film formation: Subsequently, heat treatment is performed to solidify the SAMs layer.

[0056] Preparation of S3 and perovskite light-absorbing layer 4: A perovskite precursor solution is deposited on the first charge transport layer 3 using a slit coating method, and then crystallized to form a perovskite light-absorbing layer 4.

[0057] S4. Fabrication of the second charge transport layer 5: C was sequentially deposited on the perovskite light-absorbing layer 4 by evaporation. 60 The first layer, along with a SnO2 layer deposited by atomic layer deposition, together constitute the second charge transport layer 5.

[0058] S5, P2 lines A second laser scribing is performed to form a P2 scribing line 8 that penetrates the first charge transport layer 3, the perovskite light-absorbing layer 4, and the second charge transport layer 5. The P2 scribing line 8 is used to expose the underlying FTO front electrode, preparing for the series connection of sub-cells.

[0059] Preparation of S6 and back electrode 6 On the structure with P2 scribing completed, a metal or transparent conductive oxide layer is deposited by magnetron sputtering to form the back electrode layer 6.

[0060] S7, P3 marking and edge clearing: A third laser scribing process is used to form a P3 scribing line 9 that penetrates the first charge transport layer 3, the perovskite light-absorbing layer 4, the second charge transport layer 5, and the back electrode layer 6, thereby realizing the electrical series connection between the sub-cells. Subsequently, a laser edge cleaning process is performed to remove excess film layers in the edge areas to facilitate subsequent encapsulation and connection of external leads 10.

[0061] A third aspect of this application provides a photovoltaic module, which includes the solar cell of the second aspect of this application. Thus, by integrating a solar cell with intrinsically high performance and high reliability, it not only possesses higher initial efficiency at the time of manufacture but also exhibits superior power retention and durability throughout its entire life cycle, providing core technological support for the long-term reduction of the levelized cost of electricity (LCOE) of photovoltaic power plants.

[0062] The following section will present performance tests on the fabrication method of the perovskite solar cell provided in the embodiments of this application, as well as related comparative examples.

[0063]

Example 1

[0064] Step 202, Homogenization: Place a doctor blade made of silicone rubber approximately 5 cm behind the coating head. Control the doctor blade's movement speed to match the linear speed of the slot coating. By adjusting the doctor blade's cutting depth and maintaining an angle of approximately 30° between its blade and the wet film surface, a contact pressure of approximately 0.1 kPa to 1 kPa is generated between the doctor blade and the substrate supporting the wet film.

[0065] The scraping operation of the doctor blade creates a controllable shear force field inside the wet film, which effectively promotes the directional arrangement of SAMs molecules and the uniform spread of the solution, thereby obtaining a highly uniform and continuous first charge transport layer 3.

[0066] Step 203, film formation: Subsequently, heat treatment is performed to solidify the SAMs layer.

[0067] Step 3: Preparation of perovskite light-absorbing layer 4 FAI, PbI2, MACl, MAI, and CsI were mixed in a specific molar ratio and dissolved in 1 mL of solvent (DMF:NMP = 5:1) to obtain CsI. 0.05 FA 0.9 MA 0.05 PbI3 perovskite precursor solution; A perovskite precursor solution is coated on the first charge transport layer 3 using a slit coating method, and then crystallized to form a perovskite light-absorbing layer 4.

[0068] Step 4: Fabrication of the second charge transport layer 5 On the perovskite light-absorbing layer 4, 20 nm of C was sequentially deposited by vapor deposition. 60 The first layer, along with a 20 nm SnO2 layer deposited by atomic layer deposition, together constitute the second charge transport layer 5.

[0069] Step 5, draw a line on P2 A second laser scribing is performed to form a P2 scribing line 8 that penetrates the first charge transport layer 3, the perovskite light-absorbing layer 4, and the second charge transport layer 5. The width of the P2 scribing line 8 is 50 μm, and the distance between the P2 scribing line 8 and the P1 scribing line is 20 μm. The P2 scribing line 8 is used to expose the underlying FTO front electrode to prepare for the series connection of sub-cells.

[0070] Step 6: Preparation of back electrode 6 On the structure with P2 scribing 8 completed, ITO / Cu / ITO composite layers of 30nm / 100nm / 50nm were sequentially prepared as back electrode layer 6 by magnetron sputtering.

[0071] Step 7: Marking and cleaning edges on P3 A third laser scribing process is used to form a P3 scribing line 9 that penetrates the first charge transport layer 3, the perovskite light-absorbing layer 4, the second charge transport layer 5, and the back electrode layer 6. The width of the P3 scribing line 9 is 150 μm, and the distance between the P3 scribing line 9 and the P2 scribing line 8 is 50 μm, thereby realizing the electrical series connection between the sub-cells. Subsequently, a laser edge cleaning process is performed to remove excess film layers in the edge areas to facilitate subsequent encapsulation and connection of external leads 10.

[0072]

Example 2

[0073] Step 202, Homogenization: Place a doctor blade made of silicone rubber approximately 5 cm behind the coating head. Control the doctor blade's movement speed to match the linear velocity of the slot coating. By adjusting the doctor blade's cutting depth and maintaining an angle of approximately 30° between its blade and the wet film surface, a contact pressure of approximately 0.1 kPa to 10 kPa is generated between the doctor blade and the substrate supporting the wet film.

[0074] The scraping operation of the doctor blade creates a controllable shear force field inside the wet film, which effectively promotes the directional arrangement of SAMs molecules and the uniform spread of the solution, thereby obtaining a highly uniform and continuous first charge transport layer 3.

[0075] Step 203, film formation: Subsequently, heat treatment is performed to solidify the SAMs layer.

[0076]

Example 3

[0077] Step 202, Homogenization: Place a doctor blade made of silicone rubber approximately 5 cm behind the coating head. Control the doctor blade's movement speed to match the linear speed of the slot coating. By adjusting the doctor blade's cutting depth and maintaining an angle of approximately 30° between its blade and the wet film surface, a contact pressure of approximately 1 kPa to 5 kPa is generated between the doctor blade and the substrate supporting the wet film.

[0078] The scraping operation of the doctor blade creates a controllable shear force field inside the wet film, which effectively promotes the directional arrangement of SAMs molecules and the uniform spread of the solution, thereby obtaining a highly uniform and continuous first charge transport layer 3.

[0079] Step 203, film formation: Subsequently, heat treatment is performed to solidify the SAMs layer.

[0080]

Example 4

[0081] Step 202, Homogenization: Place a doctor blade made of silicone rubber approximately 5 cm behind the coating head. Control the doctor blade's movement speed to match the linear speed of the slot coating. By adjusting the doctor blade's cutting depth and maintaining an angle of approximately 30° between its blade and the wet film surface, a contact pressure of approximately 5 kPa to 10 kPa is generated between the doctor blade and the substrate supporting the wet film.

[0082] The scraping operation of the doctor blade creates a controllable shear force field inside the wet film, which effectively promotes the directional arrangement of SAMs molecules and the uniform spread of the solution, thereby obtaining a highly uniform and continuous first charge transport layer 3.

[0083] Step 203, film formation: Subsequently, heat treatment is performed to solidify the SAMs layer.

[0084]

Example 5

[0085] Step 202, Homogenization: Place a doctor blade made of silicone rubber approximately 5 cm behind the coating head. Control the doctor blade's movement speed to match the linear speed of the slot coating. By adjusting the doctor blade's cutting depth and maintaining an angle of approximately 30° between its blade and the wet film surface, a contact pressure of less than 0.1 kPa is generated between the doctor blade and the substrate supporting the wet film.

[0086] The scraping operation of the doctor blade creates a controllable shear force field inside the wet film, which effectively promotes the directional arrangement of SAMs molecules and the uniform spread of the solution, thereby obtaining a highly uniform and continuous first charge transport layer 3.

[0087] Step 203, film formation: Subsequently, heat treatment is performed to solidify the SAMs layer.

[0088]

Example 6

[0089] Step 202, Homogenization: Place a doctor blade made of silicone rubber approximately 5 cm behind the coating head. Control the doctor blade's movement speed to match the linear velocity of the slot coating. By adjusting the doctor blade's cutting depth and maintaining an angle of approximately 30° between its blade and the wet film surface, a contact pressure of approximately 11 kPa to 15 kPa is generated between the doctor blade and the substrate supporting the wet film.

[0090] The scraping operation of the doctor blade creates a controllable shear force field inside the wet film, which effectively promotes the directional arrangement of SAMs molecules and the uniform spread of the solution, thereby obtaining a highly uniform and continuous first charge transport layer 3.

[0091] Step 203, film formation: Subsequently, heat treatment is performed to solidify the SAMs layer.

[0092] Comparative Example 1 Everything else is the same as in Example 1, except that there is no homogenization process, specifically: Step 2: Fabrication of the first charge transport layer 3 On the FTO front electrode layer 2 with P1 markings, a 20 nm thick NiO layer was first deposited using magnetron sputtering. x Layer. Subsequently, a self-assembled monolayer was prepared using the homogenization method of this application. x The layer and the SAMs layer together constitute the first charge transport layer 3, which specifically includes: Step 201, Wet film coating: Using the slit coating method, wet film is applied to the aforementioned NiO film. x A SAMs solution, which is a Me-4PACZ ethanol solution with a concentration of 0.7 mg / mL, is coated onto the layer to form a continuous wet film with an initial thickness of approximately 5 μm.

[0093] Step 202, film formation: Subsequently, heat treatment is performed to solidify the SAMs layer.

[0094] Comparative Example 2 Everything else is the same as in Example 2, except that there is no homogenization process. Specifically: Step 201, Wet film coating: Using the slit coating method, wet film is applied to the aforementioned NiO film. x A SAMs solution, which is a Ph-4PACZ ethanol solution with a concentration of 0.9 mg / mL, is coated onto the layer to form a continuous wet film with an initial thickness of approximately 5 μm.

[0095] Step 202, film formation: Subsequently, heat treatment is performed to solidify the SAMs layer.

[0096] Comparative Example 3 Everything else is the same as in Example 1, except that there is no homogenization process, specifically: Step 2: Fabrication of the first charge transport layer 3 On the FTO front electrode layer 2 with P1 markings, a 20 nm thick NiO layer was first deposited using magnetron sputtering. x Layer. Subsequently, a self-assembled monolayer was prepared using the homogenization method of this application. x The layer and the SAMs layer together constitute the first charge transport layer 3, which specifically includes: Step 201, Wet film coating: Using the slit coating method, wet film is applied to the aforementioned NiO film. x A SAMs solution, which is a Me-4PACZ ethanol solution with a concentration of 0.7 mg / mL, is coated onto the layer to form a continuous wet film with an initial thickness of approximately 5 μm.

[0097] Step 202, Homogenization: Place a stainless steel doctor blade approximately 5 cm behind the coating head. Control the doctor blade's movement speed to match the linear velocity of the slot coating. By adjusting the doctor blade's cutting depth and maintaining an angle of approximately 30° between its blade and the wet film surface, a contact pressure of approximately 0.1 kPa to 1 kPa is generated between the doctor blade and the substrate supporting the wet film.

[0098] The scraping operation of the doctor blade creates a controllable shear force field inside the wet film, which effectively promotes the directional arrangement of SAMs molecules and the uniform spread of the solution, thereby obtaining a highly uniform and continuous first charge transport layer 3.

[0099] Step 203, film formation: Subsequently, heat treatment is performed to solidify the SAMs layer.

[0100] [Test Example] The variable factors for Examples 1-6 and Comparative Examples 1-3 are shown in Table 1. The solar cells of Examples 1-6 and Comparative Examples 1-3 were subjected to IV tests, and the test results are shown in Table 2.

[0101] The fill factor (FF) used in this article refers to the ratio of the actual maximum obtainable power (Pm or Vmp × Jmp) to the theoretical (not actually obtainable) power (Jsc × Voc). Therefore, FF can be determined by the following formula: FF = (Vmp × Jmp) / (Jsc × Voc), where Jmp and Vmp represent the current density and voltage at the maximum power point (Pm), respectively, which is obtained by changing the resistance in the circuit until J × V reaches its maximum value; Jsc and Voc represent the short-circuit current and open-circuit voltage, respectively. The fill factor is a key parameter for evaluating solar cells. Commercial solar cells typically have a fill factor of approximately 60% or higher.

[0102] The open-circuit voltage (Voc) used in this paper is the potential difference between the anode and cathode of the device under conditions of no external load connection.

[0103] The short-circuit current (Isc) used in this article is the maximum current flowing through the output terminal of a photovoltaic cell or module when it is short-circuited (voltage V=0) under STC conditions.

[0104] The power conversion efficiency (PCE) of solar cells used in this article refers to the percentage of power converted from absorbed light into electrical energy. The PCE of a solar cell can be measured under standard test conditions (STC) based on incident light irradiance (E: W / m²). 2 ) and the surface area of ​​solar cells (Ac:m 2 The STC is calculated by dividing by the point of maximum power (Pm). STC typically refers to the value at a temperature of 25°C and an irradiance of 1000 W / m². 2 The spectrum of air quality 1.5 (AM1.5).

[0105] Accelerated aging tests of MPPT100h@85℃ were conducted on the batteries of Examples 1-6 and Comparative Examples 1-3. The tests were conducted based on the IEC 62804 standard to obtain the conversion efficiency after aging, and then the conversion efficiency decay rate was obtained. The conversion efficiency decay rate = (initial conversion efficiency - conversion efficiency after aging) / initial conversion efficiency × 100%.

[0106] Table 1

[0107] Table 2:

[0108] As shown in Tables 1 and 2, the stability of perovskite devices fabricated using the method described in this application is also improved. The main reason is that the improved uniformity of the SAMs layer also improves the uniformity of the perovskite layer, thereby enhancing the photothermal stability of the device. Furthermore, the depth at the P1 location is approximately 500-600 nm. In conventional slot coating processes (comparative example), SAMs material easily accumulates, leading to abnormal perovskite crystallization. During photothermal aging, the perovskite decomposes first at the abnormally crystallized areas at P1, causing device instability. The coating method used in this application, which fills P1 with a soft scraper, avoids the accumulation of SAMs in the P1 trench, thus preventing abnormal perovskite crystallization at the P1 location and improving device stability.

[0109] Furthermore, as shown in Table 2 above, different SAMs materials significantly affect the photothermal stability of perovskite devices. Devices prepared with Me-4PACz exhibit worse photothermal stability than those prepared with Ph-4PACz, which is determined by the molecular structure of the SAMs materials themselves. The perovskite device prepared in Comparative Example 2 showed a degradation of approximately 1.5% after aging at 85°C for 100 hours using MPPT. The device prepared in Example 2 not only showed improved efficiency but also, after aging under the same conditions, exhibited an efficiency increase of 1.2%. This is because the preparation method described in this application improves the uniformity of SAM film formation, thereby enhancing both device efficiency and stability.

[0110] Compared to Comparative Example 1, Examples 3, 4, and 5 provided suitable contact pressure to the liquid film of Me-4PACz, thereby forming a shear force field. This allowed Me-4PACz to form a more uniform film layer, and no material accumulation occurred in the P1 trench, improving the device's efficiency and stability. However, Example 1 provided too low a contact pressure compared to Comparative Example 1, failing to form a shear force field. Although it slightly improved the uniformity of Me-4PACz, Me-4PACz still accumulated in the P1 trench, limiting the improvement in device efficiency and stability. Example 6 provided too high a contact pressure compared to Comparative Example 1, resulting in an excessively large shear force field. This caused the Me-4PACz to fail to form a continuous film layer and damaged the NiOx film layer on the substrate, leading to a loss of device efficiency and a decrease in stability. Comparative Example 3 used a hard stainless steel scraper, which also damaged the NiOx film layer on the substrate, resulting in a loss of device efficiency and a decrease in stability.

[0111] This application embodiment can also provide a photovoltaic module (not shown), which includes the solar cell described above. The solar cell can be connected in series and / or in parallel with one or more other solar cells in a predetermined manner. Multiple cells can form a cell string, and adjacent cells can be connected together by string welding.

[0112] It should be noted that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. The directional terms "inner" and "outer" refer to the inside or outside relative to the outline of the component itself. For example, if a device in the drawings is inverted, a device described as "above" or "on top of" other devices or structures will subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0113] It should also be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this application refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0114] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0115] It should also be noted that the above are merely preferred embodiments of this application and do not limit the scope of patent protection of this application. Any equivalent structural or procedural changes made using the content of this application’s specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A method for preparing a hole transport layer, characterized in that, include: Preparation of wet films including single-molecule self-assembled materials; An external force is applied to disturb the wet film, causing a shear force field to be generated within the wet film, thereby promoting the spread of the single-molecule self-assembled material within the wet film; The wet film is cured to form at least a partial hole transport layer.

2. The method for preparing a hole transport layer according to claim 1, characterized in that, The applied external force includes: The wet film is coated using a scraper. The scraper has a Shore hardness of 20A to 90A.

3. The method for preparing a hole transport layer according to claim 2, characterized in that, The material of the scraper includes at least one of polyurethane, silicone rubber, and fluororubber.

4. The method for preparing the hole transport layer according to claim 2 or 3, characterized in that, The preparation of wet films comprising single-molecule self-assembled materials includes slit coating, blade coating, or spray coating.

5. The method for preparing a hole transport layer according to claim 4, characterized in that, When the wet film is prepared using the slit coating method, the doctor blade is positioned behind the coating head that forms the wet film comprising the monomolecular self-assembled material in the coating direction, and the distance between the doctor blade and the coating head is 1 cm to 20 cm.

6. The method for preparing a hole transport layer according to claim 4, characterized in that, When the wet film is prepared using the aforementioned blade coating method, the contact pressure generated by the blade in the blade coating method is 0.1 kPa to 10 kPa; and / or In the solution used to form the wet film, the concentration of the monomolecular self-assembled material is 0.1 mg / mL to 10 mg / mL; and / or The angle between the blade of the scraper and the surface of the wet film is 10° to 60°.

7. The method for preparing a hole transport layer according to any one of claims 1-3 and 5, characterized in that, The wet film is prepared on a substrate; The substrate includes a transparent conductive layer, or the substrate includes a transparent conductive layer and a first hole transport layer located on a surface of the transparent conductive layer; a first scribe line is provided on the transparent conductive layer.

8. The method for preparing a hole transport layer according to claim 7, characterized in that, The application of external force to disturb the wet film includes: The doctor blade is used to coat the wet film to promote the spread of the monomolecular self-assembled material within the wet film. Simultaneously, the scraper is used to scrape and coat the area marked with the first line and the single-molecule self-assembled material on both sides for distribution.

9. A solar cell, characterized in that, Includes a hole transport layer prepared by the preparation method according to any one of claims 1 to 8.

10. A photovoltaic module, characterized in that, The photovoltaic module includes the solar cell as described in claim 9.

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