Preparation method of heterojunction battery, heterojunction battery and battery assembly

Abstract

The invention relates to a preparation method of a heterojunction cell, the heterojunction cell and a cell assembly, and the method comprises the steps: providing a substrate, enabling a first surface of the substrate to be provided with a first epitaxial layer, and generating a first transparent oxide layer on the first epitaxial layer; generating a layer of first metal grid on the first transparent oxide layer; and depositing a second transparent oxide layer on the first metal grid. According to the technology, the first metal grid is generated on the first transparent oxide layer, and the second transparent oxide layer is deposited on the first metal grid, so that the high conductivity and high light transmission of the whole structure are maintained while the indium-containing TCO film layer is thinned. The first metal mesh provides additional conductive channels, enhancing current conduction efficiency, while reducing dependency on indium. The first metal grid is protected by the sandwich structure, the long-term stability of the electrode is ensured, the optical performance is optimized, and the TCO film still has excellent performance under the condition that the indium content is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell preparation, and specifically provides a method for preparing a heterojunction cell, a heterojunction cell and a cell assembly. Background Art

[0002] Transparent conductive oxide (TCO) films are required in the preparation of heterojunction batteries, and indium is a very important element in TCO films. However, indium is too expensive and rare, so reducing the indium content in TCO films has become an important research direction.

[0003] However, directly thinning the indium-containing TCO film layer may lead to a decrease in the conductivity and optical performance of the TCO film layer, thereby affecting the overall performance of the optoelectronic device. Therefore, how to reduce the indium content in the TCO film layer while maintaining high conductivity and high transmittance has become an urgent problem to be solved.

[0004] Accordingly, the art needs a new method for preparing heterojunction batteries to solve the above problems. Summary of the invention

[0005] In order to overcome the above defects, the present invention is proposed to provide a solution or at least partially solve the technical problem in the prior art that the TCO film layer needs to reduce the indium content while maintaining its electrical and optical properties.

[0006] In a first aspect, the present invention provides a method for preparing a heterojunction battery, the method comprising: providing a substrate, wherein a first epitaxial layer is provided on a first surface of the substrate, a first transparent oxide layer is generated on the first epitaxial layer; a first metal grid is generated on the first transparent oxide layer; and a second transparent oxide layer is deposited on the first metal grid.

[0007] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, the first metal grid is composed of metal nanowires.

[0008] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, generating a first metal grid on the first transparent oxide layer includes: generating a first metal grid on the first transparent oxide layer using at least a first template, wherein the first metal grid includes electrode veins, and the first template includes a concave area, wherein the concave area is used to obtain the shape of the electrode veins.

[0009] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the generating a layer of first metal grid on the first transparent oxide layer using at least a first template includes: providing the first template, the first template also includes a convex area, wherein the area of ​​the convex area is larger than the concave area; placing the first template on the first transparent oxide layer, and injecting a metal nano solution into the concave area, wherein the metal nano solution includes metal nanowires and a solvent; and removing the solvent and the first template to obtain the first metal grid.

[0010] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the first metal grid is obtained after removing the solvent and the first template, including: when removing the solvent, the first template is still placed on the first transparent oxide layer for limiting and shaping the metal nanowires; until the solvent is removed, the first template is removed.

[0011] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, the concave area is obtained based on a preset network structure.

[0012] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, the first template is a flexible polymer material.

[0013] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the method also includes a method for making a first template, wherein the method for making the first template includes: using a laser to etch a substrate according to the preset network structure to obtain a substrate; placing the substrate in a molding container to obtain a mold; pouring a liquid flexible polymer material into the mold and curing it to obtain the first template.

[0014] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the solvent is a first organic solvent, wherein the vapor pressure of the first organic solvent is greater than 20 mmHg at normal temperature and pressure.

[0015] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the method includes: the substrate also includes a second surface, wherein a second epitaxial layer is provided on the second surface of the substrate, and a third transparent oxide layer is generated on the second epitaxial layer; on the third transparent oxide layer, at least a second template is used to generate a second metal grid composed of interwoven metal nanowires, wherein the second metal grid includes electrode veins, and the second template includes a concave area, wherein the concave area is used to obtain the shape of the electrode veins; and a fourth transparent oxide layer is deposited on the second metal grid.

[0016] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, the depth of the concave region is 90 nm to 270 nm.

[0017] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, the concave area is in a grid shape, and the grid line width is 30 μm to 60 μm.

[0018] In a second aspect, the present invention provides a heterojunction battery, comprising: a substrate; a first epitaxial layer, a first transparent oxide layer, a first metal grid, a second transparent oxide layer and a metal electrode, which are sequentially generated on the substrate and located on a first surface of the substrate.

[0019] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, the first metal grid is composed of metal nanowires.

[0020] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, the line width of the first metal grid is 30 μm-60 μm.

[0021] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, the ratio of the area of ​​the electrode veins in the first metal grid to the area of ​​the first transparent oxide layer is 18% to 25%.

[0022] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, the thickness of the first metal grid is 90 nm-270 nm.

[0023] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, the number density of the metal nanowires in the first metal grid electrode vein is: 2×10 5 -2×10 6 / mm 2 , wherein the length of the metal nanowire is 10 μm-30 μm.

[0024] In a third aspect, the present invention provides a battery assembly, comprising a plurality of heterojunction batteries as described in the second aspect.

[0025] The above one or more technical solutions of the present invention have at least one or more of the following Beneficial effects:

[0026] In the technical solution of the present invention, by generating a first metal grid on the first transparent oxide layer and depositing a second transparent oxide layer thereon, the present technology achieves the maintenance of high conductivity and high light transmittance of the overall structure while thinning the indium-containing TCO film layer. The first metal grid provides an additional conductive channel, enhances the current conduction efficiency, and reduces the dependence on indium. This sandwich structure protects the first metal grid, ensures the long-term stability of the electrode, and optimizes the optical properties, so that the TCO film still has excellent performance while reducing the indium content. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In addition, similar numbers in the figures are used to represent similar components, among which:

[0028] Figure 1 is a schematic flow chart of main steps of a method for preparing a heterojunction battery according to an embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of the main structure of a substrate according to an embodiment of the present invention;

[0030] Figure 3 is a schematic diagram of the main structure of a substrate and epitaxial layers on both sides thereof according to an embodiment of the present invention;

[0031] Figure 4 is a partial structural schematic diagram of a heterojunction battery according to an embodiment of the present invention;

[0032] Figure 5 is a schematic diagram of the main structure of a heterojunction battery according to an embodiment of the present invention;

[0033] Figure 6 It is a schematic flow chart of the steps of obtaining a first metal grid in a method for preparing a heterojunction battery according to an embodiment of the present invention;

[0034] Figure 7 is a schematic diagram of a process for obtaining a first template in a method for preparing a heterojunction battery according to an embodiment of the present invention;

[0035] Figure 8 Schematic diagram of a partial structure of a metal grid according to an embodiment of the present invention.

[0036] List of reference numerals:

[0037] 1. substrate; 101. second surface; 102. first surface; 2. first transparent oxide layer; 3. first metal grid; 4. second transparent oxide layer; 5. metal electrode; 6. third transparent oxide layer; 7. second metal grid; 8. fourth transparent oxide layer; 9. electrode veins; 10. through-hole area; 11. first epitaxial layer; 1101. first intrinsic amorphous silicon film; 1102. p-type silicon film; 12. second epitaxial layer; 1201. n-type silicon film; 1202. second intrinsic amorphous silicon film. DETAILED DESCRIPTION

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0039] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0040] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0041] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0042] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0043] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0044] Embodiment 1:

[0045] See attached Figure 1 , Figure 1 FIG. 1 is a schematic flow chart of the main steps of a method for preparing a heterojunction battery according to an embodiment of the present invention. Figure 1 and Figure 5 As shown, the method for preparing a heterojunction battery in the embodiment of the present invention mainly includes the following steps S10 to S30.

[0046] Step S10 : providing a substrate 1 , wherein a first epitaxial layer 11 is formed on a first surface 102 of the substrate 1 , and a first transparent oxide layer 2 is formed on the first epitaxial layer 11 .

[0047] like Figure 2 As shown, Figure 2 Schematic diagram of the structure of substrate 1. In one embodiment, substrate 1 includes a first surface 102 and a second surface 101.

[0048] like Figure 3 As shown, Figure 3 It is a structural diagram of the epitaxial layers on both sides of the substrate. A first epitaxial layer 11 is provided on the first side 102 of the substrate 1. A second epitaxial layer 12 is provided on the second side 101 of the substrate 1. The first epitaxial layer 11 and the second epitaxial layer 12 are both composite structures. In the direction from the first side 102 to the second side 101, the second epitaxial layer 12 includes an n-type silicon film 1201 and a second intrinsic amorphous silicon film 1202. In the same direction, the first epitaxial layer includes a first intrinsic amorphous silicon film 1101 and a p-type silicon film 1102. The n-type crystalline silicon substrate has been cleaned and textured on both sides.

[0049] In this embodiment, the substrate 1 is an n-type crystalline silicon substrate.

[0050] like Figure 4 As shown, Figure 4 Only the structure of the heterojunction cell along the first surface 102 from the substrate 1 is shown, that is, part of the results of the heterojunction cell. After the structural preparation of the multilayer substrate 1 is completed, the first transparent oxide layer 2 is deposited on the first surface 102 of the substrate 1. The first transparent oxide layer 2 can be made of a transparent conductive oxide (TCO), including but not limited to ITO (indium tin oxide), IWO (indium tungsten oxide), ICO (indium copper oxide), VTTO (vanadium titanium tin oxide) or a stack thereof. These materials not only have excellent electrical conductivity, but also can effectively transmit light, thereby reducing optical losses and improving the photoelectric conversion efficiency of the heterojunction cell.

[0051] In this embodiment, a first transparent oxide layer 2 with a thickness of 10-20 nm can be uniformly deposited on the first surface 102 of the substrate 1 by a physical vapor deposition (PVD) process such as magnetron sputtering or reactive plasma deposition (RPD). During the deposition process, process parameters such as target power, gas pressure, substrate temperature and deposition time need to be precisely controlled to ensure uniformity and adhesion of the transparent oxide layer.

[0052] The main function of the first transparent oxide layer 2 is to provide a low-impedance electrode contact interface, and at the same time, through its excellent optical transmittance, maximize the utilization of light, thereby improving the photoelectric conversion efficiency of the battery. In this step, by depositing the first transparent oxide layer 2 on the substrate 1, the preliminary construction of the battery electrode is achieved, which provides the necessary foundation for the subsequent formation of the first metal grid 3 structure.

[0053] In summary, through the meticulous structural design of the substrate 1 and the high-precision deposition of the first transparent oxide layer 2, this step ensures good interface bonding between the key functional layers of the heterojunction battery, effectively improving the overall performance and long-term stability of the battery.

[0054] Step S20 : ​​forming a first metal grid 3 on the first transparent oxide layer 2 .

[0055] In this embodiment, the first metal grid 3 is composed of metal nanowires.

[0056] In one embodiment, the first metal grid 3 is composed of metal nanowires. The reason for using metal nanowires is that metal nanowires have excellent conductivity and can provide an efficient current collection path for heterojunction batteries. At the same time, the first metal grid 3 composed of metal nanowires can maintain high light transmittance.

[0057] In this embodiment, the metal nanowire is a silver (Ag) nanowire, because the silver nanowire has excellent electrical conductivity, chemical stability and optical transparency. In this embodiment, the diameter of the silver nanowire is usually controlled between 50-100nm, and the length is between 10-30μm. Such size selection can maximize the light transmittance while ensuring good electrical conductivity, and reduce the impact on the efficiency of the photovoltaic device. At the same time, the silver nanowire of such length and diameter also facilitates the subsequent preparation of the first metal grid 3, as follows.

[0058] In one embodiment, in order to generate the first metal grid 3 on the first transparent oxide layer 2, a first template-assisted method is adopted. First, a graphical first template is prepared, and the first template has a concave area and a convex area. The convex area of ​​the first template is used to fit with the first transparent oxide layer 2, and the concave area of ​​the first template divides the convex area of ​​the first template, dividing the convex area into several blocks. The concave area of ​​the first template is a key part of forming the first metal grid 3.

[0059] like Figure 8 As shown, Figure 8 It is a partial schematic diagram of the first metal grid 3, wherein the first metal grid 3 can be divided into electrode veins 9 and through-hole areas 10, wherein the electrode veins 9 are the metal nanowire aggregation areas, and the through-hole areas 10 are mostly hollow areas surrounded by the electrode veins 9. The concave area of ​​the first template is used to assist in the production and acquisition of the electrode veins 9 of the first metal grid 3.

[0060] In this embodiment, a metal nano-solution may be prepared or purchased, and then a metal grid is generated based on the metal nano-solution and a template.

[0061] In one embodiment, the first metal grid 3 is obtained through steps S201-S203, such as Figure 6 As shown, the details are as follows:

[0062] Step S201: providing a first template, wherein the first template further comprises a convex region, wherein the area of ​​the convex region is larger than that of the concave region.

[0063] In one embodiment, the first template is made of a flexible polymer material to ensure that it can be closely attached to the surface of the first transparent oxide layer 2 during the deposition process. The flexible polymer material has excellent deformation ability, and under pressure, its protruding portion can be completely in contact with the surface of the first transparent oxide layer 2, thereby avoiding uneven deposition of nanowires caused by the air gap between the first template and the first transparent oxide layer 2.

[0064] In this embodiment, in order to ensure that the structure of the first metal grid 3 can be accurately controlled during the nanowire deposition process, the convex area of ​​the first template is designed to be larger than the concave area, and the area ratio of the convex area to the concave area is between 4 and 4.56: 1. The selection of this ratio is based on the optimization of the final electrical properties and light transmittance of the first metal grid 3, which can ensure that efficient current collection is achieved while maintaining the optical performance to the maximum extent.

[0065] Further, in one embodiment, the depth of the concave area of ​​the first template is between 90nm and 270nm, and this depth range corresponds to the thickness of the finally formed first metal grid 3. In this embodiment, this range is selected to ensure that the first metal grid 3 has sufficient conductivity while avoiding excessive light blocking, thereby affecting the photoelectric conversion efficiency.

[0066] In this embodiment, the concave area is designed as a grid, and the grid line width is between 30 μm and 60 μm. The grid line width is related to the principle of preparing the first metal grid 3, and the reason why it is designed between 30 μm and 60 μm will be described in detail later.

[0067] In this embodiment, the flexible polymer material may include one of silicone, PDMS (polydimethylsiloxane), and PU (polyurethane), which have good deformation ability and chemical stability and can maintain their structural integrity and functionality during multiple uses.

[0068] In this embodiment, by providing a first template with a specific geometric structure and flexible characteristics, precise shaping of the first metal grid 3 structure is achieved, providing a reliable process basis for subsequent nanowire deposition.

[0069] Step S202: placing the first template on the first transparent oxide layer 2 and injecting a metal nano-solution into the concave area.

[0070] In this embodiment, the metal nano-solution includes metal nano-wires and a solvent.

[0071] In one embodiment, the first template is precisely placed on the surface of the first transparent oxide layer 2. Since the first template is made of a flexible polymer material, the convex area of ​​the first template can completely fit the surface of the first transparent oxide layer 2 under moderate pressure, avoiding the generation of air gaps and ensuring that the metal nano solution can be precisely formed after being injected into the concave area.

[0072] Next, a metal nano solution is injected into the concave area of ​​the first template. The metal nano solution is composed of metal nanowires and a solvent. In this embodiment, the solvent not only helps the uniform dispersion of the metal nanowires in the solution, but also optimizes the subsequent solvent removal process. In one embodiment, the solvent is a first organic solvent, specifically, the solvent includes one of ethanol, methanol, propanol or acetone.

[0073] The solvent selection of ethanol, methanol, propanol or acetone is mainly based on three aspects: dispersibility, capillary action and ease of removal, as follows:

[0074] Dispersibility: These four organic solvents all have excellent dispersibility, which can make the silver nanowires disperse evenly in the solvent and reduce agglomeration, ensuring that after being injected into the concave area of ​​the first template, the silver nanowires can be evenly distributed to form a dense first metal grid 3 structure.

[0075] Capillary action: The capillary action of these four organic solvents is large, so that when the metal nano solution is injected into the concave area of ​​the template, it can quickly and evenly fill the concave area. Especially when the concave area is designed as a grid and the grid line width is between 30μm and 60μm, this capillary phenomenon is significantly enhanced, which helps to improve the molding accuracy and uniformity of the first metal grid 3. At the same time, the design is between 30μm and 60μm, which can make the final grid finer and ultimately achieve better results.

[0076] Easy to remove: These four solvents are highly volatile and can evaporate quickly after injection, leaving evenly distributed metal nanowires. This feature speeds up the forming of the first metal grid 3 and reduces interface contamination or unevenness that may be caused by solvent residue.

[0077] In this embodiment, the vapor pressures of the four solvents are shown in the following table: Table 1 shows the vapor pressures of the four solvents, wherein the vapor pressure of the first organic solvent is greater than 20 mmHg at normal temperature and pressure. Solvent Noun Vapor Pressure acetone 180 mmHg Methanol 90 mmHg Ethanol 44 mmHg Propanol 20 mmHg Table 1: Vapor pressure of various solvents

[0078] In this embodiment, the metal nano solution is uniformly injected into the concave area of ​​the first template, and a micro syringe can be used to ensure that the solution enters the concave area accurately and uniformly. The injected metal nano solution will then quickly fill every corner of the concave area under the action of capillary phenomenon. Since the metal nanowires are uniformly in the metal nano solution, as the metal nano solution fills every corner of the concave area, the metal nanowires are also filled into every corner of the concave area.

[0079] In this embodiment, the purpose of forming a high-precision first metal grid 3 on the surface of the transparent oxide layer is achieved by injecting the metal nano solution into the concave area of ​​the first template. The selection and control of the solvent ensures the uniform distribution and rapid molding of the metal nanowires, and thus the distribution of the metal nanowires is more uniform. Since the first template is obtained according to the preset grid structure, a first metal grid 3 with the same preset structure and uniform distribution of metal nanowires can be finally obtained in this way.

[0080] Step S203: After removing the solvent and the first template, a first metal grid 3 is obtained.

[0081] In one embodiment, the first metal grid 3 is formed by removing the solvent injected into the concave area of ​​the first template and the first template. The removal of the solvent is to ensure that the metal nanowires form a stable and uniform grid structure on the transparent oxide layer. To this end, a drying method can be used to remove the solvent by volatilizing the solvent.

[0082] Solvent removal is usually performed by drying by controlling the ambient temperature and pressure. In one embodiment, the drying methods that can be used include: vacuum drying, hot air drying, inert gas drying, etc. In vacuum drying, by reducing the ambient pressure, the volatilization of the solvent can be accelerated, while reducing the effect of the surface tension effect generated during the solvent volatilization process on the arrangement of the nanowires. This method helps to avoid agglomeration or displacement of the metal nanowires during the drying process, thereby ensuring that the formed grid structure is uniform and continuous.

[0083] Then, hot air drying uses heating and airflow to accelerate the volatilization of the solvent. In the hot air drying, the temperature is set between 40°C and 60°C, and the appropriate temperature is selected according to the volatility of the solvent. The advantage of using hot air drying is that it is easy to operate, and the solvent can be quickly and evenly removed by controlling the temperature and airflow speed. In one embodiment, the uniform deposition of metal nanowires in the concave area of ​​the template can be achieved by precisely controlling the drying conditions, and a first metal grid 3 with ideal thickness and uniformity can be formed.

[0084] In this embodiment, the solvent is removed through a precise drying process to achieve stable forming of the first metal grid 3. By controlling the drying conditions, such as temperature, pressure and airflow, it is ensured that the metal nanowires are evenly distributed in the concave area of ​​the first template, and a complete first metal grid 3 is formed after the solvent is removed.

[0085] Furthermore, when removing the solvent, the first template is still placed on the first transparent oxide layer to limit and shape the metal nanowires; until the solvent is removed, the first template is removed. When removing the solvent, if there is no restriction on the concave area of ​​the first template, the metal nanowires may be removed along with the first model, so that the original shape of the metal nano solution deviates from the design of the concave area of ​​the first model. As a result, after the solvent is removed, the first metal grid 3 is not a preset shape. Therefore, when removing the solvent, the first template needs to be still placed on the first transparent oxide layer 3 to limit and shape the metal nanowires to form a preset shape.

[0086] In summary, the first metal grid 3 obtained by this embodiment has a high degree of uniformity and precise geometric shape, and the metal nanowires are evenly distributed in the grid, ensuring the continuity and stability of the conductive path. Due to the use of the first template and the appropriate solvent, the size and shape of the grid can be precisely controlled, avoiding uneven line width or agglomeration, and ensuring the consistency of electrical performance. At the same time, the optical transparency of the grid structure is optimized, minimizing the obstruction to light transmission.

[0087] Furthermore, a transparent oxide layer film with a sandwich structure including the first metal grid 3 is finally obtained, and the transparent oxide layer film with the sandwich structure has excellent conductivity and optical transparency. The first metal grid 3 provides a low-impedance current collection channel, and the presence of the transparent oxide layer film ensures the optical transparency and mechanical stability of the overall structure. This combination enables the composite film layer to achieve efficient photoelectric conversion in photovoltaic devices while maintaining good durability and flexibility, and is suitable for high-performance heterojunction solar cells and other photovoltaic applications.

[0088] Furthermore, the preparation method of the heterojunction battery also includes a method for preparing a first template, wherein the method for preparing the first template includes steps AC, such as Figure 7 As shown, the details are as follows:

[0089] Step A: Use laser to etch the substrate according to a preset network structure to obtain a substrate.

[0090] In one embodiment, a substrate suitable for laser etching is selected, such as copper or aluminum, and then the substrate surface is pretreated, including cleaning and surface flatness adjustment, to ensure that no etching errors or irregular morphologies due to surface unevenness occur during the laser etching process.

[0091] After that, the substrate is etched using high-precision laser etching equipment. Laser etching technology removes material from the substrate surface through a focused laser beam to form a preset micro-nano structure. For example, ultraviolet lasers with a laser wavelength of 355nm are used to achieve higher etching accuracy.

[0092] During the etching process, the surface of the substrate is patterned according to a preset network structure. The network structure is usually pre-designed and imported into the control system of the laser etching device. The laser beam moves along a preset path on the surface of the substrate, and finally forms a desired grid-like or other complex-shaped structure through multiple scans and layer-by-layer material removal. In this embodiment, the shape of the smallest unit of the preset network structure can be a square, triangle, circle or other irregular shape.

[0093] In this embodiment, the substrate is used to subsequently generate a template.

[0094] Step B: placing the substrate in a molding container to obtain a mold.

[0095] In one embodiment, the substrate formed by etching in step A is placed in a molding container to prepare a mold for a flexible polymer template.

[0096] In this embodiment, the molding container material includes stainless steel, glass and high hardness polymer.

[0097] During the operation, the substrate is carefully placed at the bottom of the molding container with the etched structure on its surface facing upward. In order to prevent the substrate from moving or tilting in the molding container, the substrate is positioned and fixed to ensure that the substrate is in close contact with the bottom of the container.

[0098] After the substrate is successfully placed and fixed, the liquid flexible polymer material is poured into the molding container. At this time, the concave and convex structure on the substrate will serve as the negative mold of the mold, and the micro-nano structure on the surface of the substrate will be accurately replicated through the fluidity of the liquid polymer material.

[0099] This step provides an accurate mold foundation for the molding of flexible polymer materials by placing the substrate in the molding container. The selection of the molding container and the precise placement of the substrate ensure the high precision and high repeatability of the mold making process, laying a solid foundation for the subsequent template formation.

[0100] Step C: Pour the liquid flexible polymer material into the mold and solidify it to obtain a first template.

[0101] In this embodiment, the concave area in the first template is obtained based on a preset network structure.

[0102] In one embodiment, a liquid flexible polymer material is injected into a molding container in which a substrate has been placed, and forms a first template having a micro-nano structure through a curing process.

[0103] First, the prepared liquid flexible polymer material is evenly poured into the molding container to ensure that it completely covers the micro-nanostructure on the substrate surface. To avoid the generation of bubbles and uneven filling, vacuum-assisted injection or low-pressure injection technology can be further used to inject the liquid flexible polymer material into the mold. Vacuum-assisted injection applies a vacuum to the molding container during the injection process to exclude air and ensure that the material can fully penetrate and fill the microstructure on the substrate.

[0104] After the material is injected, the next step is to cure it. The curing method can be selected according to the type of liquid flexible polymer material used. For example, natural curing or heating curing at room temperature can be used, or ultraviolet light (UV) curing technology can be used to quickly crosslink and cure the material by irradiating ultraviolet light.

[0105] After curing, the mold is removed from the molding container and the template is carefully peeled off from the substrate. Since the flexible polymer material has good elasticity and toughness, the peeling process can be completed without damaging the micro-nano structure. The final first template accurately replicates the surface structure of the substrate and has a certain mechanical strength and flexibility to meet subsequent use requirements.

[0106] Step S30 : depositing a second transparent oxide layer 4 on the first metal grid 3 .

[0107] In this embodiment, the thickness of the first transparent oxide layer 2 or the second transparent oxide layer 4 is 10-20 nm.

[0108] In one embodiment, the process is similar to depositing the first transparent oxide layer 2 in step S10, and will not be described in detail herein.

[0109] Step S40 : preparing a metal electrode 5 on the second transparent oxide layer 4 .

[0110] In one embodiment, a metal electrode 5 is formed on the formed second transparent oxide layer 4. The function of the metal electrode 5 is to collect and conduct current while maintaining good electrical contact and mechanical bonding with the transparent oxide layer.

[0111] The material of the metal electrode 5 is usually selected from metals with high conductivity and chemical stability, such as silver, silver-clad copper or electroplated copper. The preparation of the metal electrode 5 usually adopts physical vapor deposition (PVD) or electroplating process. The PVD process includes magnetron sputtering and electron beam evaporation, which forms a uniform and highly adhesive metal film by vaporizing the metal target in a vacuum environment and depositing it on the surface of the transparent oxide layer. The parameter settings of the magnetron sputtering process include target power, gas pressure, deposition time and substrate temperature. Electron beam evaporation uses an electron beam to directly heat the metal target, so that it vaporizes in a vacuum and deposits on the substrate, which is suitable for preparing high-purity and low-stress metal films.

[0112] In this embodiment, by preparing the metal electrode 5 on the second transparent oxide layer 4, efficient collection and extraction of current is achieved, while ensuring the stable combination of the electrode and the transparent oxide layer, providing a reliable electrical interface for the efficient operation of the heterojunction battery. Through precise material selection and process control, the final metal electrode 5 has excellent conductivity, chemical stability and environmental adaptability, ensuring the long-term performance and stability of the photovoltaic device.

[0113] Furthermore, there is a third transparent oxide layer 6 on the second surface 101 of the substrate 1; the method for preparing the heterojunction battery also includes: using at least a second template to generate a second metal grid 7 composed of interwoven metal nanowires on the third transparent oxide layer 6, wherein the second metal grid 7 includes electrode veins 9, and the second template includes a concave area, wherein the concave area corresponds to the electrode veins 9; and precipitating a fourth transparent oxide layer 8 on the second metal grid 7.

[0114] Furthermore, another metal electrode 5 is prepared on the fourth transparent oxide layer 8 .

[0115] However, these steps correspond to steps S10-S30, and the technical means used therein are almost the same, so they will not be repeated here.

[0116] Furthermore, the preparation method of the heterojunction battery also includes: a preparation method of the substrate 1. As previously described, a first epitaxial layer 11 is provided on the first surface 102 of the substrate 1. A second epitaxial layer 12 is provided on the second surface 101 of the substrate 1. The first epitaxial layer 11 and the second epitaxial layer 12 are both composite structures. In the direction from the first surface 102 to the second surface 101, the second epitaxial layer 12 includes an n-type silicon film 1201 and a second intrinsic amorphous silicon film 1202. In the same direction, the first epitaxial layer includes a first intrinsic amorphous silicon film 1101 and a p-type silicon film 1102. The preparation method of substrate 1 includes: cleaning and texturing the double sides of an n-type crystalline silicon substrate; depositing a first intrinsic amorphous silicon film 1101 in the direction of the first side 102 of the n-type crystalline silicon substrate; depositing a second intrinsic amorphous silicon film 1202 in the direction of the second side 101 of the n-type crystalline silicon substrate; depositing a p-type silicon film 1102 on the first intrinsic amorphous silicon film 1101 along the direction of the first side 102; and depositing an n-type silicon film 1201 on the second intrinsic amorphous silicon film 1202 along the direction of the second side 101.

[0117] Specifically, the n-type crystalline silicon substrate is first cleaned and textured on both sides. Commonly used cleaning agents include Piranha solution (a mixture of concentrated sulfuric acid and hydrogen peroxide), hydrofluoric acid (HF) and deionized water (DI water). After cleaning, high-purity nitrogen is used for drying to avoid surface oxidation caused by residual moisture. The texturing process forms a micron-scale velvet structure on the surface of the substrate to increase the light trapping effect, reduce light reflection, and improve light absorption efficiency.

[0118] A first intrinsic amorphous silicon film 1101 is deposited on the first surface 102 of the cleaned and textured n-type crystalline silicon substrate. The film is usually deposited by a plasma enhanced chemical vapor deposition (PECVD) process. The thickness of the first intrinsic amorphous silicon film 1101 is generally controlled between 5-10 nm, and is used to passivate dangling bonds and other defects on the surface of the n-type crystalline silicon substrate, thereby reducing the surface recombination effect and increasing the life of carriers.

[0119] Similarly, a second intrinsic amorphous silicon film 1202 is deposited on the second surface 101 of the substrate, with the same thickness as the first intrinsic amorphous silicon film 1101, using the same PECVD process. The second intrinsic amorphous silicon film 1202 has a similar function to the first film, which is to passivate the crystalline silicon surface and ensure long-life carrier transmission in the substrate.

[0120] After the deposition of the intrinsic amorphous silicon film, a p-type silicon film 1102 is deposited on the first intrinsic amorphous silicon film 1101 along the first surface 102 of the substrate. The p-type silicon film 1102 is used to form the emitter layer of the solar cell, and p-type doped amorphous silicon, microcrystalline silicon or nanocrystalline silicon is usually selected. The thickness of the p-type silicon film 1102 is generally controlled between 5-15nm through PECVD deposition. The main function of the p-type silicon film 1102 is to provide selective contact and transmission paths for electrons, thereby improving the photoelectric conversion efficiency of the battery.

[0121] In the direction of the second surface 101 of the substrate, that is, on the second intrinsic amorphous silicon film 1202, an n-type silicon film 1201 is deposited. The thickness of the n-type silicon film 1201 is controlled between 10-30 nm, and is deposited using the same PECVD process as the p-type silicon film 1102. The n-type silicon film 1201 is mainly used as a hole selective contact layer, which effectively prevents the reverse transmission of photogenerated holes and reduces carrier recombination.

[0122] In this step, the light absorption capacity of the substrate is optimized by double-sided cleaning and texturing of the n-type crystalline silicon substrate; by depositing an intrinsic amorphous silicon film and a p-type / n-type silicon film 1201 on both sides, a key layer (substrate 1) in the heterojunction structure is formed, ensuring the effective separation and transmission of photogenerated carriers and improving the overall performance of the solar cell.

[0123] Furthermore, the present invention also provides a heterojunction battery, comprising:

[0124] From top to bottom, there are a substrate 1, a first transparent oxide layer 2 located on the first surface 102 of the substrate 1, a first metal grid 3, a second transparent oxide layer 4 and a metal electrode 5, wherein the first metal grid 3 is composed of metal nanowires.

[0125] Further, in one embodiment, the line width of the first metal grid 3 is 30 μm-60 μm. Further, in one embodiment, the area ratio of the electrode veins 9 in the first metal grid 3 to the area ratio of the first transparent oxide layer 2 is 18% to 25%, that is, the area ratio of the electrode veins 9 to the through-hole area 10 in the first metal grid 3 is 4 to 4.56:1. Further, in one embodiment, the thickness of the first metal grid 3 is 90 nm-270 nm.

[0126] In this embodiment, the first metal grid 3 is obtained from the first template, so the parameters thereof are the same as the concave area parameters of the first template, which will not be described in detail here.

[0127] Furthermore, the number density of the metal nanowires in the electrode veins 9 of the first metal grid 3 is: 2×10 5 -2×10 6 / mm 2, where the length of the metal nanowire is 10μm-30μm.

[0128] In one embodiment, when the length of the metal nanowire is 10 μm-30 μm, the electrode veins 9 in the first metal grid 3 have 20,000 to 200,000 metal nanowires in an area of ​​1 square millimeter. It should be noted that, since the thickness of the first metal grid 3 is thin, although the expression of area density is used here, it actually refers to the sum of the number of all metal nanowires in the longitudinal space where the area is located.

[0129] The basic concepts have been described above. Obviously, for those skilled in the art, the above application disclosure is only an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0130] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0131] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more application embodiments, in the above description of the embodiments of this application, multiple features are sometimes merged into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0132] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0133] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions may be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the essential spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A method for preparing a heterojunction battery, characterized in that: include: Providing a substrate, wherein a first epitaxial layer is provided on a first surface of the substrate, and a first transparent oxide layer is generated on the first epitaxial layer; forming a first metal grid on the first transparent oxide layer; A second transparent oxide layer is deposited on the first metal grid.

2. The method for preparing a heterojunction battery according to claim 1, characterized in that: The first metal grid is composed of metal nanowires.

3. The method for preparing a heterojunction battery according to claim 1, characterized in that: The step of generating a first metal grid on the first transparent oxide layer comprises: At least one first metal grid is generated on the first transparent oxide layer using a first template, wherein the first metal grid includes electrode veins, and the first template includes a concave area, wherein the concave area is used to obtain the shape of the electrode veins.

4. The method for preparing a heterojunction battery according to claim 3, characterized in that: The step of generating a first metal grid layer on the first transparent oxide layer using at least a first template comprises: Providing the first template, the first template further comprising a convex region, wherein the convex region has a larger area than the concave region; placing the first template on the first transparent oxide layer, and injecting a metal nano-solution into the concave area, wherein the metal nano-solution includes metal nanowires and a solvent; The first metal grid is obtained after removing the solvent and the first template.

5. The method for preparing a heterojunction battery according to claim 4, characterized in that: The first metal grid is obtained after removing the solvent and the first template, include: Wherein, when the solvent is removed, the first template is still placed on the first transparent oxide layer to limit and shape the metal nanowires; After the solvent is removed, the first template is removed.

6. The method for preparing a heterojunction battery according to claim 4, characterized in that: in, The depth of the concave area is 90nn~270nm; and / or, wherein the concave area is grid-shaped, and the grid line width is 30μm~60μm; and / or, the area ratio of the convex area to the concave area is 4~4.56:

1.

7. The method for preparing a heterojunction battery according to claim 4, characterized in that: in, The solvent is a first organic solvent, wherein the vapor pressure of the first organic solvent is greater than 20 mmHg at normal temperature and pressure.

8. The method for preparing a heterojunction battery according to any one of claims 1 to 7, characterized in that: The method comprises: The substrate further comprises a second surface, wherein a second epitaxial layer is provided on the second surface of the substrate, and a third transparent oxide layer is generated on the second epitaxial layer; At least one second template is used to generate a second metal grid composed of metal nanowires interwoven on the third transparent oxide layer, wherein the second metal grid includes electrode veins, and the second template includes a concave area, wherein the concave area is used to obtain the shape of the electrode veins; A fourth transparent oxide layer is deposited on the second metal grid.

9. The method for preparing a heterojunction battery according to claim 4, characterized in that: The method further includes a method for making a first template, wherein the method for making the first template includes: Using laser to etch the substrate according to a preset network structure to obtain a substrate; placing the substrate in a molding container to obtain a mold; The liquid flexible polymer material is poured into the mold and solidified to obtain the first template.

10. The method for preparing a heterojunction battery according to claim 4, characterized in that: in, The first template is made of a flexible polymer material.

11. The method for preparing a heterojunction battery according to claim 4, characterized in that: The solvent includes at least one of acetone, methanol, ethanol or propanol.

12. A heterojunction battery, characterized in that: include: substrate; A first epitaxial layer, a first transparent oxide layer, a first metal grid, a second transparent oxide layer and a metal electrode are sequentially generated on the substrate and located on the first surface of the substrate.

13. The heterojunction battery according to claim 12, characterized in that: in, The first metal grid is composed of metal nanowires.

14. The heterojunction battery according to claim 12, characterized in that: in, The line width of the first metal grid is 30 μm-60 μm; and / or the thickness of the first metal grid is 90 nm-270 nm.

15. The heterojunction battery according to claim 12, characterized in that: in, The ratio of the area of ​​the electrode veins in the first metal grid to the area of ​​the first transparent oxide layer is 18% to 25%.

16. The heterojunction battery according to claim 13, characterized in that: in, The number density of the metal nanowires in the first metal grid electrode vein is: 2×10 5 -2×10 6 / mm 2 , wherein the length of the metal nanowire is 10μm-30μm.

17. A battery assembly comprising a plurality of heterojunction batteries as claimed in claim 12.

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