Efficient and uniform perovskite passivation layer processing method and solar cell

Abstract

The invention discloses an efficient and uniform perovskite passivation layer processing method and a solar cell, in particular to a perovskite passivation layer processing method combining physical vapor deposition, solvent-assisted induction and an air knife drying technology, and the method combines the physical vapor deposition, the solvent-assisted induction and the air knife drying technology. The problems that in an existing perovskite passivation layer preparation method, control over the thickness of a passivation layer is not accurate, a passivation solvent possibly causes damage to a perovskite interface, and the passivation layer is not uniform due to the coffee ring effect in large-area preparation are solved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, specifically a method for treating a highly efficient and uniform perovskite passivation layer and a solar cell. Background Technology

[0002] In the large-scale production of perovskite solar cells, interface passivation is crucial for improving efficiency. Traditional solution-coating methods suffer from the following problems when preparing nanoscale ultrathin passivation layers:

[0003] 1. Difficulty in controlling the thickness and uniformity of the passivation layer: When it is necessary to prepare an ultrathin passivation layer of a few nanometers, the solution coating technology is difficult to precisely control the film thickness and is prone to forming uneven areas on the film surface.

[0004] 2. Damage to the perovskite layer interface caused by solvents: Passivating agents are usually dissolved in organic solvents. During solution coating, the solvent directly contacts the underlying perovskite film. This may cause a certain degree of dissolution, reconstruction, or side reactions in the perovskite crystal structure, thereby introducing new defects or destroying the integrity of the original interface, affecting carrier transport.

[0005] 3. The "coffee ring effect" leads to macroscopic non-uniformity: In large-area solution coating processes, during solvent evaporation, due to surface tension gradients and capillary action, solute molecules (i.e., passivators) migrate and accumulate towards the droplet edges, forming the so-called "coffee ring effect." This effect manifests as a macroscopic non-uniform distribution of the passivation layer on large-area perovskite films, resulting in regional differences in battery performance. This negative impact is particularly pronounced for passivation layers with extremely high uniformity requirements.

[0006] Therefore, the industry urgently needs a method for preparing perovskite passivation layers that can overcome the above-mentioned technical bottlenecks in order to achieve perovskite solar cells with high efficiency, high stability and excellent large-area uniformity. Summary of the Invention

[0007] The purpose of this invention is to provide a highly efficient and uniform perovskite passivation layer treatment method and a solar cell, so as to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for treating a highly efficient and uniform perovskite passivation layer and a solar cell. The method for treating a highly efficient and uniform perovskite passivation layer includes the following steps:

[0010] S1. Physical vapor deposition of ammonium salt passivation pre-deposition layer: First, an organic amine halide compound is precisely deposited on the surface of the perovskite absorber layer by vacuum evaporation to form a passivation pre-deposition layer with controllable thickness and high uniformity. This step is a dry process, avoiding direct contact between the solvent and the perovskite absorber layer;

[0011] S2. Solvent-assisted bonding and activation: Next, a solvent is coated on the surface of the pre-deposited layer. The solvent acts as an activator, wetting and slightly dissolving the evaporated ammonium salt molecules without dissolving the underlying perovskite, promoting their chemical bonding with the defect sites in the perovskite lattice, thereby achieving interface passivation.

[0012] S3. Air knife enhanced uniform drying: While or immediately after coating with alcohol solvent, the film surface is dried quickly and uniformly using an air knife process. The high-speed controlled airflow generated by the air knife forces the solvent to evaporate quickly, effectively suppressing the occurrence of the "coffee ring effect" and ensuring that the passivation molecules are highly uniformly distributed across the entire large-area substrate.

[0013] Furthermore, the organic amine halide compound is one of 1,3-propanediamine dihydroiodate (PDAI2), phenylethyl ammonium iodide (PEAI), or other organic amine halide compounds.

[0014] Furthermore, the solvent is one of isopropanol (IPA), a mixed solvent of isopropanol and N-methylpyrrolidone (IPA+NMP), or a mixed solvent of isopropanol and chlorobenzene (IPA+CB).

[0015] A perovskite solar cell containing a rising passivation layer is prepared by vapor deposition on the perovskite passivation layer prepared by the above method; subsequently, an electron transport layer is prepared by atomic layer deposition; and finally, a metal electrode layer is prepared by vapor deposition or magnetron sputtering to obtain the final perovskite solar cell structure.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. Precise control of passivation layer thickness and uniformity: A uniform passivation molecular film was prepared by vacuum evaporation technology.

[0018] 2. Effective protection of the perovskite interface: The molecules are first passivated by dry evaporation, and then solvent-assisted activation is performed. This avoids the high-concentration passivation solution from directly contacting the perovskite layer for a long time, thereby minimizing the damage and side reactions that the solvent may cause to the perovskite crystal structure.

[0019] 3. Completely eliminate the "coffee ring effect": The air knife process effectively suppresses the edge enrichment of solute during solvent evaporation through forced and uniform airflow drying, fundamentally solving the "coffee ring effect" in large-area coating and ensuring that the chemical composition and physical thickness of the passivation layer are highly uniform over a large area.

[0020] 4. Significantly Improved Device Performance and Stability: Due to the high uniformity of the passivation layer and the minimization of interface damage, the perovskite solar cells prepared by this method exhibit higher open-circuit voltage, fill factor, and photoelectric conversion efficiency. Simultaneously, the environmental barrier effect of the passivation layer and its effective defect repair also significantly enhance the long-term operational stability of the device.

[0021] 5. Suitable for large-area preparation: This composite process is easy to integrate into roll-to-roll or other large-area production lines, and has good prospects for industrial application. Attached Figure Description

[0022] Figure 1 This is a perovskite solar cell structure.

[0023] Figure 2 Comparison of PL mapping for perovskite layer surface scraping and vapor deposition + air knife PDAI2 layer.

[0024] Figure 3 SEM comparison images of two perovskite layer layers: one coated by scraping and the other by vapor deposition plus air knife.

[0025] Figure 4 XRD comparison images of two perovskite layer layers: one coated by scraping and the other by vapor deposition plus air knife.

[0026] Figure 5 JV diagram of a large-area perovskite module prepared by scraping and vapor deposition with an air knife passivation layer.

[0027] Figure 6 MPPT (Multiple-Phase Transformation) of a large-area perovskite module prepared by scraping and vapor deposition with an air knife passivation layer (illumination provided by an LED solar simulator, test temperature 25 ℃, humidity 30%).

[0028] Figure 7 Comparison of JV diagrams for perovskite devices fabricated with airflow pressures of 0.1 MPa, 0.3 MPa, and 0.5 MPa.

[0029] Figure 8 JV diagrams of perovskite devices fabricated with the distance between the air knife edge and the substrate surface set to 0.5 mm, 1 mm, and 2 mm are compared.

[0030] Figure 9JV diagram comparison of perovskite devices fabricated by moving the substrate at a constant speed of 50 mm / s, 100 mm / s, and 200 mm / s below the air knife. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0032] An example of a method for preparing a highly efficient and uniform perovskite passivation layer includes the following steps:

[0033] S1. Preparation of the perovskite absorber layer:

[0034] First, on a clean substrate (such as a glass substrate coated with a transparent conductive oxide, such as ITO or FTO), a hole transport layer (e.g., NIO, Me-4PACz, MeO-2PACz, PTAA, Poly-4PACz) and a perovskite absorber layer are sequentially prepared by methods such as spin coating, blade coating, or slot coating; the perovskite absorber layer is composed of FA. 0.9 Cs 0.1 The thickness of PbI3 is preferably 300 nm to 800 nm.

[0035] In this scheme, the perovskite absorber layer can also be prepared by coating and flash evaporation, followed by annealing at 100°C for 30 minutes to complete crystallization.

[0036] S2, Vacuum evaporation of ammonium salt passivation pre-deposited layer:

[0037] The substrate with the prepared perovskite absorber layer is transferred to a high-vacuum evaporation chamber; the vacuum level of the chamber is preferably controlled at 6*10. -4 Below Pa;

[0038] Ammonium salt passivation material is loaded into the evaporation source. By heating the evaporation source, the ammonium salt passivation material sublimates and deposits onto the surface of the perovskite absorber layer.

[0039] During the vapor deposition process in this step, the evaporation source temperature, substrate temperature, and vapor deposition rate are precisely controlled, with the preferred vapor deposition rate being 0.05 Å / s to 0.3 Å / s, in order to form a uniform thin layer with a thickness precisely controlled between 1 nm and 10 nm.

[0040] The ammonium salt passivation material is one of 1,3-propanediamine dihydroiodate (PDAI2), phenylethyl ammonium iodide (PEAI), or a certain organic amine halide.

[0041] The advantage of this step is that it is a dry deposition process, which avoids direct contact between any solvent and the perovskite absorber layer, thus protecting the integrity of the perovskite surface and laying a damage-free foundation for the subsequent passivation reaction; at the same time, vacuum evaporation ensures a highly uniform distribution of passivation molecules at the nanoscale.

[0042] S3, Solvent-assisted activation and binding:

[0043] After the vacuum evaporation of the ammonium salt passivation material is completed, the substrate is removed from the evaporation chamber. Subsequently, a solvent layer is applied to the perovskite surface with the pre-deposited passivation layer by a specific coating method, such as blade coating, slot coating, or spray coating.

[0044] The solvent is one of isopropanol (IPA), a mixed solvent of isopropanol and N-methylpyrrolidone (IPA+NMP), or a mixed solvent of isopropanol and chlorobenzene (IPA+CB), and its purity is preferably 99.9% or higher, anhydrous.

[0045] In this step, the solvent acts as a mild activator and medium; it does not significantly dissolve or damage the underlying perovskite, but it can slightly dissolve and wet the evaporated ammonium salt molecules. With the assistance of the solvent, the solid ammonium salt molecules can acquire a certain degree of migration ability and engage in effective chemical interactions with exposed defect sites (such as uncoordinated Pb2+ and halogen vacancies) on the perovskite crystal surface, for example, forming coordination bonds, ionic bonds, or inducing the formation of a two-dimensional perovskite structure, thereby achieving effective passivation of defects.

[0046] This step involves selecting a suitable solvent to ensure the effective activation of the passivation molecules while avoiding excessive erosion of the perovskite layer.

[0047] S4, air knife enhances uniform drying

[0048] While the solvent coating is being applied in the above steps, the air knife device is immediately activated to dry the surface of the wet film.

[0049] Air knife unit: An air knife unit typically consists of a high-pressure air source (e.g., nitrogen or compressed air), a precisely designed slit nozzle, and a control system. It is installed on the conveyor line of the coating process that carries out the steps described above.

[0050] In this scheme, the process parameters are as follows: the airflow pressure of the air knife is preferably controlled between 0.1 MPa and 0.5 MPa, the distance between the air knife nozzle and the substrate surface is preferably between 0.5 mm and 2 mm, the air outlet angle of the nozzle is preferably perpendicular to the substrate or inclined at 15 degrees, and the substrate moves uniformly below the air knife at a speed of (50 mm / s to 200 mm / s).

[0051] like Figure 7-9 As shown, the efficiencies of perovskite devices fabricated with air knife distances of 0.5 mm, 1 mm, and 2 mm from the substrate surface were 10.74%, 16.31%, and 12.38%, respectively. The efficiencies of perovskite devices fabricated with air knife distances of 0.5 mm, 1 mm, and 2 mm from the substrate surface were 12.23%, 16.31%, and 13.89%, respectively. The efficiencies of perovskite devices fabricated with the substrate moving uniformly below the air knife at speeds of 50 mm / s, 100 mm / s, and 200 mm / s were 11.91%, 16.31%, and 14.15%, respectively.

[0052] The air knife process employed in this invention, by introducing a forced convection mechanism, fundamentally alters the solvent evaporation kinetics, thereby effectively suppressing the "coffee ring effect."

[0053] Uniform and accelerated solvent evaporation: The high-speed, laminar airflow generated by the air knife uniformly blows across the entire wet film surface. This significantly improves and makes the evaporation rate of solvent molecules more uniform across the entire surface. Compared to natural evaporation, the forced convection of the air knife greatly reduces the boundary layer effect, ensuring that the solvent vapor diffusion resistance at the center and edges of the film tends to be consistent.

[0054] Suppressing capillary flow: Because the solvent is forced to evaporate uniformly and rapidly across the entire surface, solvent loss is no longer confined to the edges. This means that a strong capillary flow from the center to the edge is no longer needed inside the droplet to compensate for edge evaporation losses. The strong external airflow field provided by the air knife has sufficient momentum to overcome and suppress the internal capillary flow driven by the surface tension gradient.

[0055] Promoting uniform contraction or overall drying of the contact line: Under strong forced convection, the contact line of the liquid film is no longer "pinned" to a specific position, but can contract inward at a faster speed and in a more uniform manner, or the entire liquid film dries uniformly in a very short time, forming a uniform solid film. This avoids the accumulation of solute at the contact line for a long time.

[0056] Reduced concentration gradient formation: Due to the rapid and uniform removal of solvent, it is difficult for solute concentration gradients to form or be maintained within the film. Solute molecules do not have sufficient time and driving force to undergo large-scale directional migration before the solvent has completely evaporated, thus ensuring that their initial uniform distribution during evaporation is preserved.

[0057] This step is the core of achieving uniformity in a large-area passivation layer. First, uniform and dense passivation molecules of several nanometers are obtained through vapor deposition. Then, by precisely controlling the air knife parameters (such as air pressure, air speed, air knife distance and angle), the solvent evaporation kinetics can be precisely controlled, thereby obtaining a macroscopically highly uniform passivation layer. This ensures that the passivation molecules are fixed in situ and uniformly distributed on the entire large-area substrate, avoiding regional differences in the performance of the passivation layer.

[0058] A perovskite solar cell comprising a rising passivation layer is prepared by depositing an electron transport layer (fullerene, C60) on top of the perovskite passivation layer prepared by the above method; subsequently, a buffer layer (tin oxide, SnOx) is prepared by atomic layer deposition; and finally, a metal electrode layer is prepared by methods such as evaporation or magnetron sputtering. The resulting perovskite solar cell structure is as follows. Figure 1 As shown.

[0059] Performance Testing and Comparison

[0060] To investigate the differences in passivation effects of different passivation methods on perovskite surfaces, two passivation methods were employed: one involving blade coating of a passivation layer, and the other involving vapor deposition of a passivation layer followed by blade coating and air knife purging of the solvent. The perovskite film surfaces were then subjected to PL mappling tests. Figure 2 Scanning electron microscopy (SEM) test ( Figure 3 ) and X-ray diffraction (XRD) testing ( Figure 4The photoelectric properties, morphology, and crystallinity of perovskite thin films passivated by different methods were characterized. PL mapping tests showed that perovskite passivation by blade coating resulted in a significant spatial variation in the maximum value of the perovskite photoluminescence (PL) peak. The perovskite layer passivated by vapor deposition followed by air knife exhibited a narrower PL peak distribution, while a wider distribution was observed after blade coating passivation. This indicates that the perovskite film passivated by vapor deposition followed by air knife passivation is more uniform, avoiding ion separation or defect phase formation within the perovskite. Scanning electron microscopy (SEM) images showed that, compared to the control group, the perovskite grain size of the main sample was larger and the degree of crystallinity was higher. Furthermore, we found that the perovskite film surface treated by blade coating passivation had obvious pores, while the perovskite film passivated by vapor deposition followed by air knife passivation did not show obvious pinholes. This indicates that the traditional blade coating method has limited ability to passivate perovskite surface defects, while this method can effectively passivate surface defects. This also helps reduce carrier recombination at the interface. X-ray diffraction (XRD) analysis further confirmed that no additional diffraction peaks appeared in the sample after passivation with vapor deposition and air knife, indicating that no 2D perovskite impurity phase was induced. In addition, compared with the control sample, the perovskite diffraction peaks of the battery device after passivation with vapor deposition and air knife were significantly enhanced, which is consistent with the SEM results. This indicates that the perovskite film after passivation with vapor deposition and air knife has a larger grain size, higher crystallinity and no pinholes, which can help the film spread, reduce interfacial carrier recombination, and thus improve the photoelectric conversion efficiency of the device.

[0061] The perovskite solar cells fabricated using the method described in this application demonstrate excellent uniformity in large-area device testing (10 cm x 10 cm), exhibiting significant advantages, particularly in fill factor and open-circuit voltage. Figure 5 As shown, compared with the traditional scraping passivation process, this method increases the opening voltage from 11.57 V to 11.96 V, the fill factor from 73% to 75%, and the photoelectric conversion efficiency from 16.65% to 18.08%.

[0062] Long-term stability of the device is crucial for evaluating its commercial potential. We conducted maximum power point tracking tests on the module under continuous white LED illumination (≈100 mW / cm²) in a mild environment of 35±5% relative humidity and 25±5°C. Figure 6 As shown, the module exhibits excellent operational stability. The traditional scraping passivation process resulted in a photoelectric conversion efficiency dropping to 90% of its initial efficiency after 600 hours of operation. In contrast, the battery prepared using this method maintained its efficiency without reduction and even showed a 10% improvement after 800 hours of continuous aging testing. This result fully validates that the large-area perovskite module prepared using this method possesses a good working life.

[0063] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. These terms are used only for the convenience of describing this invention and for 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. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, terms such as "set" and "connect" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

Claims

1. A method for treating a highly efficient and uniform perovskite passivation layer and a solar cell, characterized in that, Includes the following steps: S1. Physical vapor deposition of ammonium salt passivation pre-deposition layer: First, an organic amine halide compound is precisely deposited on the surface of the perovskite absorber layer by vacuum evaporation to form a passivation pre-deposition layer with controllable thickness and high uniformity. This step is a dry process, avoiding direct contact between the solvent and the perovskite absorber layer; S2. Solvent-assisted bonding and activation: Next, a solvent is coated on the surface of the pre-deposited layer. The solvent acts as an activator, wetting and slightly dissolving the evaporated ammonium salt molecules without dissolving the underlying perovskite, promoting their chemical bonding with the defect sites in the perovskite lattice, thereby achieving interface passivation. S3. Air knife enhanced uniform drying: While or immediately after coating with alcohol solvent, the film surface is dried quickly and uniformly using an air knife process; the high-speed controlled airflow generated by the air knife forces the solvent to evaporate quickly, effectively suppressing the occurrence of the "coffee ring effect" and ensuring that the passivation molecules are highly uniformly distributed across the entire large-area substrate.

2. The method for treating a highly efficient and uniform perovskite passivation layer according to claim 1, characterized in that, The organic amine halide compound is one of 1,3-propanediamine dihydroiodate (PDAI2), phenylethyl ammonium iodide (PEAI), or other organic amine halide compounds.

3. The method for treating a highly efficient and uniform perovskite passivation layer according to claim 1, characterized in that, The solvent is one of isopropanol (IPA), a mixed solvent of isopropanol and N-methylpyrrolidone (IPA+NMP), or a mixed solvent of isopropanol and chlorobenzene (IPA+CB).

4. A method for treating a highly efficient and uniform perovskite passivation layer according to any one of claims 1-3, characterized in that, An electron transport layer is prepared on top of the perovskite passivation layer prepared by the above method by vapor deposition; Subsequently, an electron transport layer is prepared by atomic layer deposition, and finally, a metal electrode layer is prepared by methods such as evaporation or magnetron sputtering to obtain the final perovskite solar cell structure.

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