Method for passivating a solar cell, solar cell and photovoltaic module

Abstract

The application provides a passivation method of a solar cell, a solar cell and a photovoltaic module, which can be widely applied to the technical field of solar cells. The passivation method of the solar cell comprises the following steps: performing light treatment and electric treatment on a silicon substrate to form a cell piece; depositing a preset material on the surface of the cell piece to form a hydrogen supplement layer; wherein the preset material is different from the film layer material on the surface of the cell piece; the preset material contains hydrogen; performing annealing treatment on the cell piece containing the hydrogen supplement layer to passivate defect areas in the hydrogen in the preset material; and etching the hydrogen supplement layer by using a preset chemical agent to obtain a cell piece after hydrogen passivation. Before testing the cell piece, the hydrogen supplement layer is arranged on the surface of the cell piece, and the defect areas of the cell piece are passivated by annealing, which is beneficial to preventing carrier recombination and improving cell conversion efficiency.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and more specifically, to a passivation method for solar cells, solar cells, and photovoltaic modules. Background Technology

[0002] As a next-generation high-efficiency crystalline silicon solar cell technology, TOPCon's core advantage lies in significantly reducing carrier recombination losses at the cell surface. With the efficiency of traditional PERC cells approaching their theoretical limit (approximately 24.5%), TOPCon introduces an ultrathin SiO2 tunneling layer and doped polycrystalline silicon (n... + The polySi layer forms a passivation contact structure, improving laboratory efficiency to over 26% and mass production efficiency to over 25.5%, making it the absolute mainstream in the industry. TOPCon's passivation performance relies on a two-layer structure: a SiO2 tunneling layer (1–2nm): the quantum tunneling effect allows charge carriers to pass through while blocking hole recombination. + - The polySi layer provides field-effect passivation and enables selective charge collection. However, the polysilicon / c-Si interface exhibits a high density of interface state defects (up to 10¹² cm⁻¹). - ²eV - ¹), which leads to carrier recombination and affects battery performance. Summary of the Invention

[0003] The main objective of this application is to provide a passivation method for solar cells, a solar cell, and a photovoltaic module, so as to at least solve the problem of carrier recombination affecting cell performance in the prior art.

[0004] To achieve the above objectives, according to one aspect of this application, a passivation method for a solar cell is provided. The method includes: performing photo-treatment and electro-treatment on a silicon substrate to form a solar cell; depositing a predetermined material on the surface of the solar cell to form a hydrogen replenishment layer; wherein the predetermined material is different from the film material on the surface of the solar cell; the predetermined material contains hydrogen; annealing the solar cell containing the hydrogen replenishment layer to passivate the hydrogen-bearing defect regions in the predetermined material; wherein the defect regions include at least one of film defect regions, interface defect regions, and silicon substrate defect regions; etching the hydrogen replenishment layer with a predetermined chemical agent to obtain a hydrogen-bearing solar cell, and testing the hydrogen-bearing solar cell; wherein the predetermined chemical agent is determined by the film material and / or the predetermined material. This application, by setting a hydrogen replenishment layer on the surface of the solar cell and passivating the defect regions of the solar cell through annealing before testing, helps to prevent carrier recombination and improve the cell conversion efficiency.

[0005] Optionally, the solar cell includes a tunneling oxide passivated contact solar cell, and the deposition of a predetermined material on the surface of the solar cell to form a hydrogen replenishment layer includes:

[0006] A hydrogenated amorphous silicon layer with a thickness of 2 to 35 nm is deposited on the first surface of the tunneling oxide passivated contact cell to form a hydrogen replenishment layer; wherein the deposition power density is 30 mW / cm2 to 70 mW / cm2, the deposition dilution is 1:10 to 1:100, the deposition pressure is 100 Pa to 400 Pa, and the deposition temperature is 150 °C to 250 °C; the first surface is one or both surfaces of the tunneling oxide passivated contact cell.

[0007] Optionally, the annealing treatment of the battery cell containing the hydrogen replenishment layer to reduce the hydrogen passivation defect region in the preset material includes:

[0008] The battery cell containing the hydrogen replenishment layer is annealed at a temperature of 200 to 500 degrees Celsius for a first preset time, so as to remove the hydrogen passivation defect area in the preset material.

[0009] Optionally, the step of etching the hydrogen replenishment layer with a preset chemical agent to obtain a hydrogen passivated battery cell includes:

[0010] The hydrogen replenishment layer is removed by applying an alkali solution with a mass fraction of 0.075-0.2% at a first preset temperature to obtain a hydrogen passivated battery cell.

[0011] Optionally, the solar cell includes a heterojunction solar cell, wherein the deposition of a predetermined material on the surface of the solar cell to form a hydrogen replenishment layer includes:

[0012] A hydrogenated aluminum oxide layer with a thickness of 8 to 12 nm is deposited on the first surface of the heterojunction solar cell to form a hydrogen replenishment layer; wherein, the first surface is one or both surfaces of the heterojunction solar cell.

[0013] Optionally, the annealing treatment of the battery cell containing the hydrogen replenishment layer to reduce the hydrogen passivation defect region in the preset material includes:

[0014] The battery cell containing the hydrogen replenishment layer is annealed at a temperature of 200 to 250 degrees Celsius for a second preset time, so as to remove the hydrogen passivation defect area in the preset material.

[0015] Optionally, the hydrogen replenishment layer is etched using a preset chemical agent to obtain a hydrogen passivated battery cell, comprising:

[0016] The hydrogen replenishment layer is etched at a rate of 2 to 3 nm / min at a second preset temperature using a buffered oxide etchant to obtain a hydrogen passivated battery cell.

[0017] Optionally, the step of etching the hydrogen replenishment layer with a preset chemical agent to obtain a hydrogen passivated battery cell includes:

[0018] In the case where the film layer on the surface of the battery cell includes a high-temperature silicon nitride film and a high-temperature slurry, and a hydrogen replenishment layer is formed by depositing hydrogenated amorphous silicon, the hydrogen replenishment layer is subjected to alkaline washing to obtain a hydrogen passivated battery cell; wherein, the high temperature is used to characterize a temperature greater than a third preset temperature;

[0019] Alternatively, if the film layer on the surface of the battery cell includes a low-temperature transparent conductive oxide and a low-temperature slurry, and a hydrogen replenishment layer is formed by hydrogenated aluminum oxide, the hydrogen replenishment layer is etched by a buffer oxide etchant to obtain a hydrogen passivated battery cell; wherein, the low temperature is used to characterize a temperature lower than a fourth preset temperature, and the fourth preset temperature is lower than a third preset temperature.

[0020] To achieve the above objectives, according to another aspect of this application, a solar cell is provided, which is passivated by the above-described passivation method for solar cells.

[0021] According to another aspect of this application, a photovoltaic module is provided, comprising a solar cell prepared by the passivation method of the solar cell described above.

[0022] By applying the technical solution of this application, before testing the battery cell, a hydrogen replenishment layer is set on the surface of the battery cell, and the defective areas of the battery cell are passivated by annealing, which helps to prevent carrier recombination and improve the battery conversion efficiency. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0024] Figure 1 A schematic diagram of the structure of a solar cell provided in an embodiment of this application is shown;

[0025] Figure 2 A schematic flowchart of a passivation method for a solar cell provided in an embodiment of this application is shown.

[0026] The above figures include the following reference numerals:

[0027] 10. Silicon substrate; 11. P+ emitter; 12. Front antireflective coating; 13. Metal gate line; 14. Tunneling oxide layer; 15. Polycrystalline silicon layer; 16. Back antireflective coating; 17. Back metal electrode; 18. Passivation glass film. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application.

[0030] 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 data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover 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.

[0031] As described in the background section, in related technologies:

[0032] TOPCon (Tunnel Oxide Passivated Contact) is gaining popularity due to its high efficiency and low cost. This type of cell typically uses N-type silicon wafers as the substrate. The general manufacturing process includes: texturing, boronizing, alkaline polishing, polylution, annealing, RCA (Rich Carbon Adhesive), ALD (Alternating Layer Deposition), front and back films, screen printing, and testing. Figure 1 The diagram shown is a general structural diagram of a TOPCon battery.

[0033] As a next-generation high-efficiency crystalline silicon solar cell technology, TOPCon's core advantage lies in significantly reducing carrier recombination losses at the cell surface. With the efficiency of traditional PERC cells approaching their theoretical limit (approximately 24.5%), TOPCon introduces an ultrathin SiO2 tunneling layer and doped polycrystalline silicon (n... +The polySi layer forms a passivation contact structure, improving laboratory efficiency to over 26% and mass production efficiency to over 25.5%, making it the absolute mainstream in the industry. TOPCon's passivation performance relies on a two-layer structure: a SiO2 tunneling layer (1–2nm): the quantum tunneling effect allows charge carriers to pass through while blocking hole recombination. + - The polySi layer provides field-effect passivation and enables selective charge collection. However, the polysilicon / c-Si interface exhibits a high density of interface state defects (up to 10¹² cm⁻¹). - ²eV - ¹), leading to carrier recombination. At this point, hydrogen passivation becomes a key process for improving interface quality.

[0034] Hydrogen diffuses to the SiO2 / c-Si interface and combines with dangling bonds to form Si-H bonds, reducing the interface state density to 10¹. 0 cm - ²eV - ¹ On the order of magnitude. Experiments show that the minority carrier lifetime of unpassivated TOPCon cells is only 1–2 ms, while that after hydrogen treatment can reach over 5 ms. Hydrogen atom implantation can neutralize defect states at the grain boundaries of polycrystalline silicon, improve the conductivity of the polycrystalline silicon layer, and reduce the series resistance (R0). s However, Si-H bonds are prone to breakage above 400℃, requiring matching with subsequent metallization processes (such as laser sintering) to prevent hydrogen escape and passivation failure. In the TOPCon process, H passivation mainly occurs during the coating process (ALD, front and back films), while subsequent processes such as screen printing, photoinjection, and laser sintering all consume H. How to further improve H passivation capability is a problem we need to consider.

[0035] To address the aforementioned issues, embodiments of this application provide a passivation method for solar cells. Before testing the solar cells, a hydrogen replenishment layer is formed on the surface of the cells, and the defective areas of the cells are passivated by annealing. This helps to prevent carrier recombination and improve the cell conversion efficiency.

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0037] Figure 2 This is a schematic flowchart of a passivation method for a solar cell according to an embodiment of this application. The passivation method for the solar cell includes:

[0038] Step S100: The silicon substrate is subjected to photo-processing and electrical processing to form a solar cell;

[0039] Step S200: A preset material is deposited on the surface of the solar cell to form a hydrogen replenishment layer; wherein the preset material is different from the film material on the surface of the solar cell; the preset material contains hydrogen.

[0040] Step S300: Anneal the battery cell containing the hydrogen replenishment layer to passivate the hydrogen defect areas in the preset material, and test the hydrogen passivated battery cell; wherein, the defect areas include at least one of the film layer defect areas, interface defect areas, and silicon substrate defect areas.

[0041] Step S400: The hydrogen replenishment layer is etched using a preset chemical agent to obtain a hydrogen passivated battery cell; wherein the preset chemical agent is determined by the film material and / or a preset material.

[0042] like Figure 1 As shown, in this application, the silicon substrate 10 undergoes photo-processing and electrical processing to form a solar cell. Specifically, the silicon substrate can be an N-type substrate (n-type Si). In this application, texturing is mainly used to form a light-trapping structure, such as the pyramidal textured surface structure on the front side of the silicon substrate; boron diffusion is used to form a PN junction, such as the P+ emitter 11 disposed on the front side of the silicon substrate; alkaline polishing is used to polish the back side, preparing a smooth passivated contact interface for the back side of the silicon substrate; such as Figure 1 A passivation glass film 18 is disposed on the emitter. A tunneling oxide layer 14 is disposed on the back side of the silicon substrate. POLY is used to deposit a polycrystalline silicon layer, forming a polycrystalline silicon layer 15, i.e., n+poly, on the back side of the silicon substrate. Annealing is used for activation doping, crystallization, and hydrogen passivation to crystallize the polycrystalline silicon layer; RCA is used to clean the surface and remove contaminants; ALD is used to deposit a passivation film; the back / front film is used to deposit a silicon nitride film to form an anti-reflection film, such as... Figure 1 The device includes a front antireflective film 12 and a back antireflective film 16. Screen printing is used to form current-collecting electrodes and grid electrodes, such as the front metal grid line 13 and the back metal electrode 17. Optical processing can include texturing and antireflection treatment, while electrical processing can include junction formation, passivation, and contact formation. This application slows carrier recombination in the solar cell through hydrogen passivation before high-temperature sintering and testing / sorting. Pre-existing materials include alumina, silicon nitride, or amorphous silicon, and contain a large amount of hydrogen. This application removes the hydrogen replenishment layer by etching. Pre-existing chemical agents are determined based on the properties of the film material and the pre-existing materials. This application solves the problem of insufficient hydrogen passivation caused by drying and high-temperature sintering in the screen printing process by applying a hydrogen replenishment layer. Appropriate hydrogen replenishment layer materials, annealing temperatures, and etching agents are selected based on the type of solar cell film and electrode slurry, eliminating the need for additional masks or protective layers, reducing process steps, and improving cell efficiency while minimizing production costs and increasing production efficiency.

[0043] Optionally, the solar cell includes a tunneling oxide passivation contact cell, and a predetermined material is deposited on the surface of the solar cell to form a hydrogen replenishment layer, including:

[0044] A hydrogenated amorphous silicon layer with a thickness of 2 to 35 nm is deposited on the first surface of the passivated contact cell in the tunneling oxide layer to form a hydrogen replenishment layer; wherein the deposited power density is 30 mW / cm². 2 Up to 70mW / cm 2 The deposition dilution is 1:10 to 1:100, the deposition pressure is 100Pa to 400Pa, and the deposition temperature is 150℃ to 250℃; the first surface is one or both of the two surfaces of the tunneling oxide layer passivated contact cell.

[0045] In this application, the preset material can be amorphous silicon, and the deposition parameters during the amorphous silicon deposition process are set to meet the conditions of the battery cell fabrication process. The silane concentration or dilution is the flow ratio of silane (SiH4) gas to hydrogen (H2) gas. Of course, the deposition parameters in this application are illustrative examples, and those skilled in the art can adjust them according to their needs. The annealing temperature and the first preset annealing time can also be adjusted as needed. This embodiment removes the hydrogen replenishment layer by alkaline etching. For example, sodium hydroxide (NaOH) (i.e., caustic soda, lye, or sodium hydroxide) can be used. It is understood that different battery substrate films require different preset materials and matching chemicals for etching. For example, silicon nitride films can be etched with low-concentration alkali and buffered hydrofluoric acid solutions, but not with strong acids like hydrochloric acid and hydrofluoric acid, as this would corrode the silicon nitride film and grid lines. On the other hand, if the grid lines or outer film layer are not resistant to acid, amorphous silicon can be deposited, then annealed, and finally etched away with a low-concentration alkali.

[0046] Optionally, the battery cell containing the hydrogen replenishment layer is annealed to passivate hydrogen-defect regions in the pre-defined material, including:

[0047] The battery cell containing the hydrogen replenishment layer is annealed at a temperature of 200 to 500 degrees Celsius for a first preset time to passivate the hydrogen-defect areas in the preset material.

[0048] Optionally, the hydrogen replenishment layer is etched using a preset chemical agent to obtain a hydrogen passivated battery cell, including:

[0049] The hydrogen replenishment layer is removed by applying an alkali with a mass fraction of 0.075-0.2% at a first preset temperature to obtain a hydrogen passivated battery cell.

[0050] Optionally, the solar cell includes a heterojunction solar cell, on which a predetermined material is deposited to form a hydrogen replenishment layer, including:

[0051] A hydrogenated aluminum oxide layer with a thickness of 8 to 12 nm is deposited on the first surface of the heterojunction solar cell to form a hydrogen replenishment layer; wherein, the first surface is one or both surfaces of the heterojunction solar cell.

[0052] Optionally, the battery cell containing the hydrogen replenishment layer is annealed to passivate hydrogen-defect regions in the pre-defined material, including:

[0053] The battery cell containing the hydrogen replenishment layer is annealed at a temperature of 200 to 250 degrees Celsius for a second preset time to passivate the hydrogen-defect areas in the preset material.

[0054] Optionally, the hydrogen replenishment layer is etched using a preset chemical agent to obtain a hydrogen passivated battery cell, including:

[0055] The hydrogen replenishment layer is etched at a rate of 2 to 3 nm / min at a second preset temperature using a buffered oxide etchant to obtain a hydrogen passivated battery cell.

[0056] In other embodiments, such as for heterojunction solar cells, the preset material can be alumina, and the annealing temperature and the second preset time can also be adjusted as needed. Buffered oxide etchant (BOE) is a wet chemical etching and cleaning agent, a buffer solution of hydrofluoric acid (HF) and ammonium fluoride (NH4F) mixed in a certain proportion, where the proportion refers to the molar concentration ratio of NH4F to HF. Using an alumina multi-hydrogen film layer, hydrogen diffuses into the cell interior during annealing to passivate defects, thereby improving the cell's conversion efficiency. Finally, excess film is removed without negatively impacting cell efficiency optically, while simultaneously cleaning the cell surface.

[0057] Optionally, the hydrogen replenishment layer is etched using a preset chemical agent to obtain a hydrogen passivated battery cell, including:

[0058] In the case where the film layer on the surface of the solar cell includes a high-temperature silicon nitride film and a high-temperature slurry, and a hydrogen replenishment layer is formed by depositing hydrogenated amorphous silicon, the hydrogen replenishment layer is alkali washed to obtain a hydrogen passivated solar cell; wherein, the high temperature is used to characterize a temperature greater than a third preset temperature;

[0059] Alternatively, if the film layer on the surface of the solar cell includes a low-temperature transparent conductive oxide and a low-temperature slurry, and a hydrogen replenishment layer is formed by hydrogenated aluminum oxide, the hydrogen replenishment layer is etched by a buffer oxide etchant to obtain a hydrogen passivated solar cell; wherein, low temperature is used to characterize a temperature lower than a fourth preset temperature, and the fourth preset temperature is lower than a third preset temperature.

[0060] In some embodiments, the high-temperature silicon nitride film mainly refers to the silicon nitride film's ability to withstand the high-temperature process (peak temperature approximately 750-800°C) of subsequent electrode sintering without performance degradation. The high-temperature paste is a front-side silver conductive paste designed to match the high-temperature silicon nitride film. Different etching chemicals and etching processes are set for different properties of preset materials and the characteristics of the cell film materials.

[0061] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the passivation method for solar cells of this application will be described in detail below with reference to specific embodiments.

[0062] TOPCon process flow: texturing, boron diffusion, alkaline polishing, POLY, annealing, RCA, ALD, front and back films, screen printing & testing. After ALD and front and back films are applied to the solar cell, hydrogen passivation is achieved. However, the drying and high-temperature sintering in the subsequent printing process inevitably cause hydrogen overflow in the front and back films of the solar cell and at the interface between the film and the silicon wafer, resulting in insufficient hydrogen passivation. Therefore, a hydrogen replenishment process is added after screen printing and before testing.

[0063] Hydrogen replenishment process:

[0064] Step 1: Deposit aluminum oxide, silicon nitride, or amorphous silicon hydrogen replenishment layer using PECVD or ALD coating (preferably choose a material for the hydrogen replenishment layer that is different from the outermost film of the solar cell to minimize the impact on the outermost film of the solar cell when removing the hydrogen replenishment layer later).

[0065] Step 2: Then anneal at 200-250℃ to activate the free hydrogen and passivate defect areas in the film layer, interface defect areas, and internal defect areas of the silicon substrate.

[0066] Step 3: After annealing, the deposited hydrogen replenishment layer is etched away (using a weakly acidic buffer oxide to remove aluminum oxide, hydrochloric acid to remove excess silicon nitride, and a low-concentration alkali to remove amorphous silicon), ensuring that the thickness of the film layer on the front side of the solar cell is within the normal optical path design. Finally, normal testing and sorting are performed.

[0067] Table 1

[0068]

[0069] Referring to Table 1, the baseline is a battery prepared using existing technology, and the experimental group consists of batteries prepared using the method provided in this application. In terms of electrical performance, the Voc increases by 1.1 mV after further passivation of the battery cells using a hydrogen supplementation process. This is mainly because H diffuses into the battery cell during annealing after alumina deposition, further passivating internal defects and thus increasing the open-circuit voltage. Simultaneously, it increases the battery's pFF, resulting in a 0.14% increase in the battery cell's FF, and ultimately a 0.1% increase in efficiency.

[0070] Understandably, the typical TOPCon battery process is as follows:

[0071] Texturing → Boron expansion → Alkali polishing → Poly → Annealing → RCA → ALD → Back film → Front film → Screening (sintering) → Sorting.

[0072] The passivation process enhanced by hydrogen supplementation is as follows:

[0073] Texturing → Boron diffusion → Alkali polishing → Poly → Annealing → RCA → ALD → Back film → Front film → Screen printing (sintering) → Hydrogen deposition → Annealing (hydrogen diffusion) → Cleaning → Sorting. Hydrogen deposition involves depositing a film layer with a high hydrogen content (alumina, silicon nitride, or amorphous silicon, etc.); annealing provides energy to the hydrogen in the high-hydrogen film layer, allowing it to move to defect locations inside the cell for passivation, achieving the effect of hydrogen replenishment passivation; cleaning removes dust from the cell surface and removes the hydrogen replenishment film layer deposited on the front side of the cell, ensuring the front side of the cell maintains a normal optical path and maximizes sunlight absorption.

[0074] Example 1: Using a 210R size silicon wafer, 182.3 210mm, respectively following the TOPCon normal production process and the hydrogen supplementation and passivation process.

[0075] A 5nm intrinsic amorphous silicon passivation layer is applied to both the front and back of the silicon wafer using a fabrication process with a power density of 30mW / cm². 2 Up to 70mW / cm 2 (Example, 50mW / cm) 2 SiH4:H2 = 1:10 to 1:100 (exemplary, optional 1:50); deposition pressure is 100 Pa to 400 Pa (exemplary, optional 200 Pa); deposition temperature is 150 °C to 250 °C (exemplary, optional 200 °C).

[0076] After amorphous silicon deposition, the cells are annealed at 200℃ for 10 minutes (the first preset time). Then, they are washed with an alkaline solution of 0.075-0.2% NaOH (mass fraction) at 5℃ (the first preset temperature), using a low concentration of alkali to react with the amorphous silicon and remove it from the cell surface. Finally, the cells are dried and tested for sorting.

[0077] Understandably, different battery base films require different passivation films and matching chemicals for etching. For example, silicon nitride films can be etched with low-concentration alkali and buffered hydrofluoric acid solutions, but not with strong acids such as hydrochloric acid and hydrofluoric acid, which would corrode the silicon nitride film and grid lines. On the other hand, if the grid lines or outer film are not resistant to acid, amorphous silicon can be deposited, then annealed, and finally etched away with a low-concentration alkali.

[0078] Example 2: The heterojunction ITO + low temperature slurry process adopts the following steps: (hydrogen deposition → annealing (hydrogen diffusion) → cleaning → sorting).

[0079] Hydrogen deposition was performed using ALD to deposit a layer of aluminum oxide approximately 10±2 nm thick at the edges of the front and back sides of the solar cell. The specific process is shown in Table 2, where TMA stands for trimethylaluminum. After aluminum oxide deposition, the cells were annealed at 200-250℃ (optionally 225℃) for 30 minutes (i.e., the second preset time). After annealing, cleaning was performed, and the cleaning process is shown in Table 3.

[0080] Table 2

[0081]

[0082] Table 3

[0083]

[0084] NH4F buffers HF activity, with an etching rate of 2-3 nm / min (20℃, i.e., the second preset temperature). It causes almost no damage to the ITO substrate and provides good protection for the substrate film. On the other hand, the etching solution does not corrode the silver gate. The size of the silver gate is about 10 μm, while the thickness of our etching is about 10 nm, which is 1000 times, three orders of magnitude. Silver itself does not react with HF. Short-term, low-concentration buffered chemical etching has almost no damage to the gate line. Moreover, after etching, the area is immediately cleaned in a water tank and dried.

[0085] Explanation of the principle:

[0086] An alumina multihydrogen film is used to passivate defects by allowing hydrogen to diffuse into the cell during annealing, thereby improving the cell's conversion efficiency. Finally, the excess film is removed without negatively impacting the cell's efficiency or optical performance, while also cleaning the cell surface.

[0087] It is known that TCO (ITO) is resistant to low concentrations of HF and NaOH, but not to HCl; silicon nitride films are resistant to low concentrations of HF and NaOH, but not to mixed solutions of HF and HCl; high-temperature slurry grid lines are not resistant to strong acids (glass oxides), have some resistance to low-activity acids, and are more resistant to weak alkalis; low-temperature slurries do not contain glass oxides, have resistance to non-oxidizing acids, and low-temperature slurries containing resins have some resistance to weak alkalis, but are not resistant to high concentrations of alkalis.

[0088] Therefore, the following methods can be used: high-temperature silicon nitride film + high-temperature slurry, using the deposition of amorphous silicon + low-concentration alkali; or low-temperature ITO film + low-temperature slurry, low-temperature ALD + HF buffering activity HF method, followed by water washing after etching, both of which can achieve the desired result.

[0089] This application solves the problem of insufficient hydrogen passivation caused by drying and high-temperature sintering in the screen printing process by applying a hydrogen replenishment layer. By selecting appropriate hydrogen replenishment layer materials, annealing temperatures and etching agents according to the battery film layer and electrode paste type, no additional mask or protective layer is required, reducing process steps and improving battery efficiency while minimizing production costs and increasing production efficiency.

[0090] This application provides a method for enhancing the passivation of solar cells. The method involves depositing a multi-hydrogen film layer after sintering the cell mesh, followed by annealing to promote hydrogen passivation and supplementing the internal passivation of the cell. Finally, the deposited multi-hydrogen film layer is removed. Solar cells include TOPCon cells, HJT cells, BC cells, tandem cells, etc.; the materials for the multi-hydrogen film layer include alumina, silicon nitride, or amorphous silicon. The annealing and hydrogen-promoting passivation temperature must not exceed the process temperature of passivation-type cells. For example, the annealing temperature for HJT cells must be <250℃, while the temperature range for TOPCon cells can be 200-500℃, ensuring that hydrogen from the multi-hydrogen film layer enters the cell for passivation. The removal of the multi-hydrogen film layer is performed using appropriate acid or alkali solutions depending on the film properties. For example, alumina is removed using an NH4F buffered HF active solution.

[0091] To achieve the above objectives, according to another aspect of this application, a solar cell is provided, which is passivated by the above-described passivation method for solar cells, the solar cell comprising a tunnel oxide passivated contact cell and a heterojunction cell.

[0092] According to another aspect of this application, a photovoltaic module is provided, comprising a solar cell prepared by the passivation method of the solar cell described above.

[0093] It should be noted that the above are merely illustrative examples and do not specifically limit the methods and steps provided in this application.

[0094] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are 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 of this application.

[0095] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0096] 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 based on the specific circumstances.

[0097] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0098] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0099] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0101] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A passivation method for a solar cell, characterized in that, The passivation method for the solar cell includes: Silicon substrates are photo- and electro-treated to form solar cells. A predetermined material is deposited on the surface of the battery cell to form a hydrogen replenishment layer; wherein, the predetermined material is different from the film material on the surface of the battery cell; the predetermined material contains hydrogen. The battery cell containing the hydrogen replenishment layer is annealed to passivate the hydrogen-defect regions in the preset material; wherein the defect regions include at least one of film layer defect regions, interface defect regions, and silicon substrate defect regions. The hydrogen replenishment layer is etched using a preset chemical agent to obtain a hydrogen passivated battery cell, and the hydrogen passivated battery cell is then tested; wherein the preset chemical agent is determined by the film material and / or the preset material.

2. The passivation method for solar cells according to claim 1, characterized in that, The solar cell includes a tunneling oxide layer passivated contact solar cell, and the deposition of a predetermined material on the surface of the solar cell to form a hydrogen replenishment layer includes: A hydrogenated amorphous silicon layer with a thickness of 2 to 35 nm is deposited on the first surface of the passivated contact cell in the tunneling oxide layer to form a hydrogen replenishment layer; wherein the deposited power density is 30 mW / cm². 2 Up to 70mW / cm 2 The deposition dilution is 1:10 to 1:100, the deposition pressure is 100Pa to 400Pa, and the deposition temperature is 150℃ to 250℃; the first surface is one or both of the two surfaces of the tunneling oxide layer passivated contact cell.

3. The passivation method for solar cells according to claim 2, characterized in that, The annealing process performed on the battery cell containing the hydrogen replenishment layer to remove the hydrogen passivation defect regions in the preset material includes: The battery cell containing the hydrogen replenishment layer is annealed at a temperature of 200 to 500 degrees Celsius for a first preset time, so as to remove the hydrogen passivation defect area in the preset material.

4. The passivation method for solar cells according to claim 2, characterized in that, The process of etching the hydrogen replenishment layer with a preset chemical agent to obtain a hydrogen passivated battery cell includes: The hydrogen replenishment layer is removed by applying an alkali solution with a mass fraction of 0.075-0.2% at a first preset temperature to obtain a hydrogen passivated battery cell.

5. The passivation method for solar cells according to claim 1, characterized in that, The solar cell includes a heterojunction solar cell, wherein a predetermined material is deposited on the surface of the solar cell to form a hydrogen replenishment layer, including: A hydrogenated aluminum oxide layer with a thickness of 8 to 12 nm is deposited on the first surface of the heterojunction solar cell to form a hydrogen replenishment layer; wherein, the first surface is one or both surfaces of the heterojunction solar cell.

6. The passivation method for solar cells according to claim 5, characterized in that, The annealing process performed on the battery cell containing the hydrogen replenishment layer to remove the hydrogen passivation defect regions in the preset material includes: The battery cell containing the hydrogen replenishment layer is annealed at a temperature of 200 to 250 degrees Celsius for a second preset time, so as to remove the hydrogen passivation defect area in the preset material.

7. The passivation method for solar cells according to claim 5, characterized in that, The hydrogen replenishment layer is etched using a preset chemical agent to obtain a hydrogen passivated battery cell, comprising: The hydrogen replenishment layer is etched at a rate of 2 to 3 nm / min at a second preset temperature using a buffered oxide etchant to obtain a hydrogen passivated battery cell.

8. The passivation method for solar cells according to claim 1, characterized in that, The process of etching the hydrogen replenishment layer with a preset chemical agent to obtain a hydrogen passivated battery cell includes: In the case where the film layer on the surface of the battery cell includes a high-temperature silicon nitride film and a high-temperature slurry, and a hydrogen replenishment layer is formed by depositing hydrogenated amorphous silicon, the hydrogen replenishment layer is subjected to alkaline washing to obtain a hydrogen passivated battery cell; wherein, the high temperature is used to characterize a temperature greater than a third preset temperature; Alternatively, if the film layer on the surface of the battery cell includes a low-temperature transparent conductive oxide and a low-temperature slurry, and a hydrogen replenishment layer is formed by hydrogenated aluminum oxide, the hydrogen replenishment layer is etched by a buffer oxide etchant to obtain a hydrogen passivated battery cell; wherein, the low temperature is used to characterize a temperature lower than a fourth preset temperature, and the fourth preset temperature is lower than a third preset temperature.

9. A solar cell, characterized in that, The solar cell is passivated by the solar cell passivation method as described in any one of claims 1 to 8.

10. A photovoltaic module, characterized in that, The photovoltaic module includes a solar cell prepared by the passivation method of a solar cell as described in any one of claims 1 to 8.

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