Preparation method of BC battery and BC battery

Abstract

The embodiment of the application discloses a preparation method of a BC battery and the BC battery. The preparation method comprises the following steps: firstly, forming first regions and second regions in an interdigital alternating arrangement on a first surface of a silicon substrate; wherein the doping structures in the first regions and the second regions are different; then, respectively performing silk screen printing and sintering treatment on the first regions and the second regions to form electrode structures; finally, performing a texturing treatment on a second surface of the silicon substrate, and forming an isolation layer on the second surface of the silicon substrate to obtain the BC battery; wherein the first surface and the second surface are two mutually facing away surfaces of the silicon substrate, and the isolation layer protrudes from the second surface of the silicon substrate. By using the above method, the protection of the front surface of the BC battery is realized by preparing the isolation layer, the risk of the texturing structure of the front surface of the BC battery being scratched is reduced, the loss of the electrical performance of the BC battery caused by the surface scratch is reduced, and the method is suitable for the inter-sheet isolation of the BC battery.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more particularly to a method for preparing a BC cell and the BC cell itself. Background Technology

[0002] Back-contact (BC) cells, also known as fully back-electrode contact (or fully reverse-electrode contact) crystalline silicon photovoltaic cells, are solar cells where the PN junction and electrodes are located on the back of the cell; that is, both the emitter and base electrodes are located on the back. BC cells have no grid lines obstructing the front, meaning the front is fully exposed to sunlight. This significantly improves the photoelectric conversion performance and light absorption efficiency of BC cells, resulting in high efficiency, great development potential, and reduced current transmission paths, lower resistance, and further improved performance.

[0003] However, because the front of the BC battery has no grid lines to shield it, the front film layer comes into direct contact with other BC batteries during the production process. This makes the front of the BC battery prone to scratches during the unloading process, affecting its appearance. Currently, existing BC batteries use separator paper to separate adjacent cells, but separator paper is expensive, and cell collection is cumbersome. Furthermore, the separator paper needs to be manually placed on the loading / unloading platform inside the machine, requiring operators to frequently check and handle alarms, wasting manpower. Additionally, the separator paper is not recyclable, resulting in a high overall production cost for BC batteries. Summary of the Invention

[0004] This invention provides a method for preparing a BC battery and a BC battery. The method utilizes an insulating layer to protect the front side of the BC battery, reducing the risk of scratches on the front side of the BC battery, minimizing the loss of electrical performance caused by scratches, and effectively reducing production costs.

[0005] In a first aspect, embodiments of the present invention provide a method for preparing a BC battery, comprising:

[0006] A first region and a second region are formed on a first surface of a silicon substrate in an alternating interdigitated pattern; wherein the doping structures in the first region and the second region are different.

[0007] The first region and the second region are respectively screen-printed and sintered to form an electrode structure;

[0008] The second surface of the silicon substrate is texturized, and an isolation layer is formed on the second surface of the silicon substrate to obtain the BC battery; wherein the first surface and the second surface are two mutually opposite surfaces of the silicon substrate, and the isolation layer protrudes from the second surface of the silicon substrate.

[0009] Optionally, the material of the insulating layer includes one or any combination of ink, insulating adhesive, hot melt adhesive, PP, PET, EVA or POE.

[0010] Optionally, the isolation layer occupies 10%-80% of the area of ​​the second surface.

[0011] Optionally, the isolation layer includes a plurality of protrusion structures.

[0012] Optionally, a plurality of the protrusions are uniformly distributed on one side of the second surface of the silicon substrate.

[0013] Optionally, the spacing between any two adjacent protrusions is in the range of 0.5mm-1.5mm.

[0014] Optionally, the height of the protrusion structure ranges from 0.1mm to 0.5mm.

[0015] Optionally, the isolation layer is transparent.

[0016] Optionally, an isolation layer is formed on the second surface of the silicon substrate, comprising:

[0017] An isolation material is printed on the second surface of the silicon substrate, and the isolation material is cured to form the isolation layer.

[0018] Secondly, embodiments of the present invention also provide a BC battery, which is prepared using the BC battery preparation method described in any one of the first aspects.

[0019] This invention provides a method for fabricating a BC battery and the BC battery itself. The method first forms an interdigitated alternating first region and a second region on a first surface of a silicon substrate. The first and second regions have different doping structures. Then, the first and second regions are screen-printed and sintered respectively to form electrode structures. Finally, the second surface of the silicon substrate is texturized, and an isolation layer is formed on the second surface of the silicon substrate to obtain the BC battery. The first and second surfaces are two opposing surfaces of the silicon substrate, and the isolation layer protrudes from the second surface of the silicon substrate. Using the above method, the isolation layer protrudes from the second surface of the silicon substrate, meaning the isolation layer has a certain thickness. By fabricating the isolation layer, the front side of the BC battery is protected, reducing the risk of scratches on the textured surface of the BC battery and minimizing the loss of electrical performance caused by surface scratches. This method is suitable for inter-cell isolation of BC batteries, avoiding direct contact between the surface of the BC battery and the surfaces of adjacent BC batteries on other feeding platforms. It eliminates the need for isolation paper and effectively reduces the total production cost of the BC battery. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic flowchart of a method for preparing a BC battery according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of a BC battery provided in an embodiment of the present invention. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0024] The terminology used in the embodiments of this invention is for the purpose of describing specific embodiments only and is not intended to limit the invention. It should be noted that directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this invention. Furthermore, in the context, it should be understood that when referring to an element being formed "on" or "below" another element, it can be formed not only directly on or below the other element, but also indirectly on or below it through intermediate elements. The terms "first," "second," etc., are used for descriptive purposes only and do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] The term "comprising" and its variations as used in this invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment".

[0026] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish the corresponding contents and are not used to limit the order or interdependence.

[0027] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0028] Figure 1 This is a schematic flowchart illustrating a method for preparing a BC battery according to an embodiment of the present invention. This method is applicable to the preparation of BC batteries and can be used to prepare BC batteries. Figure 1 As shown, the preparation method includes:

[0029] S110, A first region and a second region are formed on a first surface of a silicon substrate in an alternating interdigitated pattern; wherein the doping structures in the first region and the second region are different.

[0030] First, it should be noted that the silicon substrate provided in this embodiment is not limited to a specific type of silicon substrate. For example, the silicon substrate can be a P-type monocrystalline silicon wafer or an N-type monocrystalline silicon wafer. The silicon substrate includes a first surface and a second surface that are opposite to each other. Exemplarily, the first surface can be understood as the back surface of the silicon substrate (the back surface of the silicon substrate can also be understood as the surface on which gate lines are subsequently disposed), and the second surface can be understood as the front surface of the silicon substrate (the front surface of the silicon substrate can also be understood as the surface on which gate lines are not subsequently disposed). Exemplarily, the first and second surfaces of the silicon substrate can be rectangular in shape, with the long side of the rectangle being 183.75 mm and the short side being 182.2 mm.

[0031] The first surface of the silicon substrate can be a polished surface. Exemplarily, the first surface of the silicon substrate can be subjected to alkaline polishing to ensure it is polished, thereby forming a highly reflective polished surface. This improves the flatness of the battery surface and increases the reflection of long-wavelength light, promoting secondary light absorption, increasing short-circuit current, and reducing leakage current. Exemplarily, the alkaline polishing treatment can use a mixed solution of 38 L of concentrated potassium hydroxide (KOH) solution, 10 L of additive (BP55), and 460 L of pure water. The alkaline polishing treatment time can be 280 s, and the alkaline polishing treatment temperature can be 75°C. Exemplarily, the size of the cubes whose morphology is tested under a microscope is 8-12 micrometers. Subsequently, interdigitated alternating first and second regions can be formed on the first surface of the silicon substrate.

[0032] Specifically, a first region and a second region are formed on the first surface of the silicon substrate in an alternating interdigitated pattern. For example, the first region can be a P-region and the second region can be an N-region. This embodiment does not impose specific limitations or special requirements on the specific implementation of forming the P-region and N-region on the first surface of the silicon substrate. The specific method of forming the P-region and N-region on the back side of the silicon substrate can be determined according to the specific type of silicon substrate and the type of BC battery to be fabricated.

[0033] For example, when the BC cell to be prepared is an N-type BC cell, the process of forming P-regions and N-regions on the back side of the N-type silicon substrate may include the following: First, a tunneling oxide layer and an intrinsic poly layer can be grown on the first surface (back side) of the N-type silicon substrate. Then, the first surface of the N-type silicon substrate is subjected to boron diffusion doping treatment to obtain a P-poly layer and a BSG layer. An etching paste is printed on the second region (N-region) on the first surface of the N-type silicon substrate to etch the BSG layer, P-poly layer and tunneling oxide layer, and then dried. Finally, the etching paste is cleaned and the surface is cleaned. Subsequently, a tunneling oxide layer and an intrinsic poly layer are grown on the cleaned first surface of the N-type silicon substrate. Then, phosphorus diffusion doping is performed on the first surface of the N-type silicon substrate to obtain an N-poly layer and a PSG layer. Etching paste is printed onto the first region (P-region) and gap region on the first surface of the N-type silicon substrate, the PSG layer is etched, and the layer is dried to isolate the P / N regions. Then, the etching paste is cleaned and the surface is cleaned, resulting in a P / N intersecting BC structure on the first surface of the N-type silicon substrate. Thus, P-regions and N-regions are fabricated on the back side of the N-type silicon substrate. Furthermore, on one side of the cleaned N-type silicon substrate, atomic layer deposition (ALD), low-pressure chemical vapor deposition (LPCVD), plasma-enhanced chemical vapor deposition (PECVD), and coating processes can be used to form a passivation layer (which can be an aluminum oxide layer) and an anti-reflection layer (which can be a silicon nitride layer) on the first surface of the N-type silicon substrate to achieve passivation and anti-reflection effects. Moreover, the specific processes for forming P-regions and N-regions on the back side of the silicon substrate in N-type BC cells, as well as the specific processes for forming P-regions and N-regions on the back side of the silicon substrate in other types of BC cells, can refer to existing technologies, and will not be described in detail in this embodiment.

[0034] S120. Screen printing and sintering are performed on the first and second regions respectively to form an electrode structure.

[0035] Specifically, screen printing is one of the core processes in the manufacturing of BC batteries, primarily used for electrode forming. This process utilizes the basic principle that the paste passes through the mesh openings of the screen in the patterned areas, while the paste does not pass through the mesh openings in the non-patterned areas. During the printing process, the paste is precisely extruded onto the silicon substrate through the mesh openings of the screen, and the paste is evenly distributed on the surface of the BC battery in the form of conductive lines, forming the desired electrode pattern. Typically, the paste used for screen printing can include, but is not limited to, silver paste. The pattern formed by screen printing includes metal grid lines. High-temperature sintering is used to process the electrode material screen-printed onto the surface of the battery cell at high temperatures, drying the paste on the silicon substrate, burning off the organic components of the paste, and allowing the paste to etch through the passivation film layer and connect with the PN junction. This allows the metal grid lines to form a good ohmic contact with the silicon substrate, achieving the purpose of collecting and discharging current.

[0036] Furthermore, the BC battery after screen printing is sintered at a temperature of 742 degrees Celsius, and then undergoes a light injection process. For example, the light injection temperature can be 538 degrees Celsius, and the light intensity can be 5500 W / m². 2 Laser-induced processing following light injection can induce silver-silicon interdiffusion, thereby significantly reducing contact resistance, increasing the fill factor of the cell, and effectively improving cell efficiency. For example, the laser power in the laser-induced process can be 18W, and the reverse voltage applied to the cell terminal can be 28V.

[0037] The first surface of the silicon substrate has interdigitated alternating first and second regions. Exemplarily, the first region can be a P-region and the second region can be an N-region. Based on this, screen printing and sintering are performed on the first region to form an electrode structure. This can be understood as printing and forming a main gate and fine gate lines in the P-region. Screen printing and sintering are performed on the second region to form an electrode structure. This can be understood as printing and forming a main gate and fine gate lines in the N-region. Exemplarily, the electrode structure formed in the first region can be a negative electrode, and the electrode structure formed in the second region can be a positive electrode. This embodiment is merely an example and is not intended to be limiting.

[0038] S130. The second surface of the silicon substrate is texturized and an isolation layer is formed on the second surface of the silicon substrate to obtain a BC cell; wherein the first surface and the second surface are two mutually opposite surfaces of the silicon substrate, and the isolation layer protrudes from the second surface of the silicon substrate.

[0039] Specifically, the second surface of the silicon substrate is texturized to create a textured surface. For example, the textured surface exhibits a pyramidal structure under a microscope. Texturing removes organic contaminants and metallic impurities from the silicon substrate surface, eliminates the mechanical damage layer generated during the silicon substrate wire cutting process, reduces recombination centers, and creates an uneven textured surface. This facilitates the use of the light-trapping effect, increasing the silicon substrate's absorption rate of sunlight, reducing reflectivity, and simultaneously increasing the surface area of ​​the silicon substrate, thereby increasing the area of ​​the PN junction formed on the surface. For example, the texturing process can use a mixed solution of 36 L of concentrated potassium hydroxide (KOH) solution, 8 L of texturing additive, and 440 L of pure water, with a texturing time of 480 s and a texturing temperature of 75°C.

[0040] After the second surface of the silicon substrate is textured, an insulating layer protruding from the second surface of the silicon substrate needs to be formed to obtain the desired BC cell. This insulating layer can be used to achieve inter-cell isolation of the BC cell, providing protection for the front side of the BC cell, reducing the risk of scratches on the textured structure of the front side of the BC cell, and reducing the loss of electrical performance caused by surface scratches. The insulating layer protrudes from the second surface of the silicon substrate, separating the surface of the BC cell from the surfaces of adjacent BC cells on the unloading platform, forming a gap, and preventing the surface of the BC cell from directly contacting the surfaces of other adjacent BC cells on the unloading platform. In other words, the insulating layer is attached to the second surface of the silicon substrate without changing the original structure and manufacturing process of the BC cell. It only needs to be formed in the last step of the manufacturing process, which can effectively reduce production costs.

[0041] Furthermore, after the second surface of the silicon substrate is textured, and before an isolation layer protruding from the second surface of the silicon substrate is formed, atomic layer deposition (ALD), low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), and coating processes can be used to form a passivation layer (which can be an aluminum oxide layer) and an antireflection layer (which can be a silicon nitride layer) on one side of the second surface of the silicon substrate to achieve passivation and antireflection effects.

[0042] It should also be noted that Table 1 is a performance table of the BC battery prepared by the method of preparing a BC battery according to an embodiment of the present invention. As shown in Table 1, the BC battery prepared in this embodiment has been tested and found to be effective. Compared with the scheme of using separator paper to achieve inter-cell isolation of the BC battery, the BC battery in this embodiment uses a separator layer to achieve inter-cell isolation of the BC battery. This method does not have an adverse effect on the performance parameters of the BC battery, such as photoelectric conversion efficiency Eta, open circuit voltage Voc, short circuit current Isc, fill factor FF, series resistance Rs, parallel resistance Rsh, and reverse leakage current Irev. Moreover, the preparation steps of this separator layer are simpler than those of separator paper, which is conducive to further reducing the total production cost of the BC battery.

[0043] Table 1

[0044]

[0045] The technical solution in this embodiment of the invention involves first forming an interdigitated alternating first region and a second region on a first surface of a silicon substrate. The first and second regions have different doping structures. Then, the first and second regions are screen-printed and sintered respectively to form electrode structures. Finally, the second surface of the silicon substrate is texturized, and an isolation layer is formed on the second surface to obtain a BC battery. The first and second surfaces are two opposing surfaces of the silicon substrate, and the isolation layer protrudes from the second surface. Using this method, the isolation layer protrudes from the second surface of the silicon substrate, meaning it has a certain thickness. This isolation layer protects the front side of the BC battery, reducing the risk of scratches on the textured surface and minimizing electrical performance loss due to surface scratches. It is suitable for inter-cell isolation of BC batteries, preventing direct contact between the surface of the BC battery and the surfaces of adjacent BC batteries on other feeding platforms. It eliminates the need for isolation paper, effectively reducing the total production cost of BC batteries.

[0046] Optionally, forming an isolation layer on the second surface of a silicon substrate includes: printing an isolation material on the second surface of the silicon substrate and curing the isolation material to form the isolation layer.

[0047] For example, the isolation material can be ink, that is, the material of the isolation layer formed can be ink. Specifically, the isolation material can be printed on the second surface of the silicon substrate by screen printing, and then cured. At this time, either thermosetting or photocuring can be used simultaneously to achieve the effect of curing ink dots. For example, Table 2 shows the preparation parameters of screen printing corresponding to ink dots provided in the embodiments of the present invention. The screen printing parameters corresponding to ink dot printing can be referred to Table 2.

[0048] Table 2

[0049]

[0050] Optionally, the material of the insulating layer includes one or any combination of ink, insulating adhesive, hot melt adhesive, PP, PET, EVA or POE.

[0051] Specifically, these materials can form good adhesion on the second surface of the silicon substrate, avoiding the risk of scratches on the textured surface of the fabricated BC battery, and thus serving as inter-cell isolation. For example, the material of this isolation layer can be ink, the main component of which is resin, which is inexpensive and can reduce the overall production cost.

[0052] Optionally, the isolation layer accounts for 10%-80% of the area of ​​the second surface.

[0053] Specifically, the isolation layer covers a portion of the second surface of the silicon substrate, which helps reduce the absorption of incident light and the impact on its own photoelectric conversion efficiency caused by the isolation layer. The isolation layer occupies 10%-80% of the area of ​​the second surface. Within this range, the isolation layer can effectively and reliably protect the front side of the BC cell while ensuring a sufficiently high transmittance, thereby improving the solar energy conversion efficiency. Furthermore, exemplarily, when the isolation layer occupies less than 10% of the area of ​​the second surface, the area of ​​the isolation layer is too small. Due to factors such as unevenness of the transmission platform, potential curvature of the front side of the BC cell, and vibration or jitter during transmission, the isolation layer cannot effectively protect the front side of the BC cell, and there is still a possibility that a local area of ​​the front side of the BC cell may come into contact with adjacent BC cells on other unloading platforms. Exemplarily, when the isolation layer occupies more than 80% of the area of ​​the second surface, the area of ​​the isolation layer is too large, resulting in significant light loss when incident light passes through the isolation layer, leading to a low transmittance, which is detrimental to achieving a high photoelectric conversion efficiency for the BC cell.

[0054] Furthermore, on the second surface of the silicon substrate, the isolation layer can be configured as a continuous structure or as a discrete structure.

[0055] In one specific embodiment, when the isolation layer is configured as a continuous structure, it can be configured as any suitable shape such as rectangular, circular, annular, zigzag, curved, or irregular. For example, the isolation layer can be disposed in the central region of the second surface of the silicon substrate, with a uniform gap between the edge of the isolation layer and the edge of the second surface of the silicon substrate, thereby enabling the isolation layer to provide uniform and stable support to the front side of the BC cell.

[0056] In another specific embodiment, when the isolation layer is configured as a discrete structure, it can be configured to include multiple spaced-apart isolation units, each of which protrudes from the second surface of the silicon substrate, and the multiple isolation units together form the isolation layer. The multiple isolation units can be uniformly distributed on the second surface of the silicon substrate in a rectangular array, ring array, W-shaped array, X-shaped array, etc. Of course, the multiple isolation units can also be randomly and non-uniformly distributed on the second surface of the silicon substrate; this embodiment is merely an example and not a limitation. Furthermore, it is understood that each isolation unit can be configured as any suitable shape, such as rectangular, circular, ring-shaped, polygonal, curved, or irregular, and the shape of each isolation unit can be determined according to actual needs.

[0057] Optionally, the isolation layer includes multiple protrusions.

[0058] Specifically, the raised structure can be understood as the aforementioned isolation unit, with each raised structure spaced apart from the others, meaning they are distributed at intervals on the second surface of the silicon substrate. On one hand, the raised structures form multiple dispersed small-area shields on the second surface of the silicon substrate, thereby reducing the loss of incident light as it passes through the isolation layer. On the other hand, each raised structure forms a support point on the second surface of the silicon substrate. Multiple raised structures forming multiple dispersed support points on the second surface of the silicon substrate provide stable support for the textured surface of the silicon substrate, preventing scratches caused by contact between the front of the BC battery and adjacent BC batteries on other loading platforms. For example, the material of the isolation layer can be ink, in which case each raised structure is an ink dot. This raised structure can be obtained by adding a printing process on the second surface of the silicon substrate, printing small and dense patterns. Furthermore, this embodiment does not impose specific requirements or special limitations on the number of protrusions in the isolation layer, the arrangement of the protrusions in the isolation layer, the shape of each protrusion in the isolation layer, or the differences between adjacent protrusions. As long as the inter-cell isolation function of the BC battery can be achieved, it is within the protection scope of this embodiment.

[0059] Optionally, multiple protrusions are evenly distributed on one side of the second surface of the silicon substrate.

[0060] Specifically, the uniformly distributed protrusions can uniformly shield the textured surface of the second surface of the silicon substrate, thereby ensuring a uniform distribution of incident light on the second surface. Furthermore, the uniformly distributed protrusions can create uniform support points on the second surface, ensuring even weight distribution and preventing localized scratches due to uneven stress. Further, multiple protrusions can be uniformly distributed on one side of the second surface of the silicon substrate in a rectangular array, with the two perpendicular sides of the second surface forming the rows and columns of the rectangular array, thus adapting the arrangement of the protrusions to the shape of the second surface. For example, when multiple protrusions are evenly distributed on one side of the second surface of the silicon substrate in a rectangular array, the number of protrusions should be no less than 9. Taking 9 protrusions as an example, the 9 protrusions can be distributed in a 3×3 (3 rows and 3 columns) rectangular array. That is, each side of the second surface of the silicon substrate is provided with 3 protrusions, and the center of the second surface of the silicon substrate is provided with 1 protrusion, thereby providing support for the edge and center of the second surface of the silicon substrate, effectively avoiding local scratches on the second surface of the silicon substrate due to uneven force.

[0061] Furthermore, it is understood that the multiple protrusions may also be unevenly distributed on one side of the second surface of the silicon substrate. For example, the multiple protrusions may be unevenly distributed on one side of the second surface of the silicon substrate in a random manner. This embodiment will not provide further examples.

[0062] Optionally, the spacing between any two adjacent protrusions can range from 0.5mm to 1.5mm.

[0063] Specifically, within this range, a small gap can be maintained between two adjacent protrusions, effectively preventing localized areas of the second surface of the silicon substrate from contacting adjacent BC cells on other feeding stages. For example, the spacing between any two adjacent protrusions can be 1 mm. Furthermore, for example, when the spacing between any two adjacent protrusions is greater than 1.5 mm, the excessive spacing makes the second surface of the silicon substrate highly susceptible to contact with adjacent BC cells on other feeding stages at the location between the two protrusions, resulting in localized damage. For example, when the spacing between any two adjacent protrusions is less than 0.5 mm, the insufficient spacing hinders the absorption of incident light by the second surface of the silicon substrate and significantly increases the difficulty of the fabrication process.

[0064] Optionally, the height of the protrusion structure ranges from 0.1mm to 0.5mm.

[0065] Specifically, within this range, the protrusion structure itself can maintain high structural strength, thereby providing stable support for the textured structure of the second surface of the silicon substrate and avoiding the adverse limitation of the protrusion structure on the overall thickness of the fabricated BC cell. Furthermore, for example, when the height of the protrusion structure is greater than 0.5 mm, the height is too large, which is detrimental to the thinning and miniaturization design of the BC cell; when the height of the protrusion structure is less than 0.1 mm, the height is too small, providing insufficient support for the textured structure of the second surface of the silicon substrate, potentially leading to localized contact between the second surface of the silicon substrate and adjacent BC cells on other unloading platforms.

[0066] Optionally, the isolation layer can be transparent.

[0067] Specifically, an isolation layer is formed on the second surface of the silicon substrate. This isolation layer can be transparent, meaning it can be made of a transparent material, allowing incident light to pass through smoothly into the silicon substrate. Furthermore, the transparent isolation layer has good light transmittance and no optical gain effect. In other words, the isolation layer only has light transmittance and does not produce any optical gain effect. When incident light passes through the isolation layer and illuminates the second surface of the silicon substrate, there is no significant difference compared to incident light directly illuminating the second surface of the silicon substrate. This minimizes the influence of the isolation layer on the incident light and maintains the uniformity of the incident light distribution on the second surface of the silicon substrate. In other words, the presence of this isolation layer does not affect the light absorption and photoelectric conversion efficiency of the fabricated BC solar cell.

[0068] Based on the same inventive concept, embodiments of the present invention also provide a BC battery. Figure 2 This is a schematic diagram of the structure of a BC battery provided in an embodiment of the present invention, as shown below. Figure 2 As shown, the BC battery is prepared using the BC battery preparation method provided in any of the embodiments of the present invention. Therefore, the BC battery possesses the functional modules and beneficial effects corresponding to the BC battery preparation method.

[0069] Continue to refer to Figure 2The BC battery includes an N-type silicon substrate 10, a first region and a second region located on one side of the first surface of the N-type silicon substrate 10, and a textured structure and an isolation layer 20 located on the second surface of the N-type silicon substrate 10. The isolation layer 20 includes multiple protrusions 21. The first region can be understood as a P-region, which includes at least a P-poly layer 31 and a BSG layer 32, and an electrode structure is formed therein. The second region can be understood as an N-region, which includes at least an N-poly layer 41 and a PSG layer 42, and an electrode structure is formed therein. A first passivation layer 51 is also disposed on the side of the BSG layer 32 away from the first surface of the N-type silicon substrate 10, and a first passivation layer 51 is also disposed on the side of the PSG layer 42 away from the first surface of the N-type silicon substrate 10. A second passivation layer 52 may also be disposed between the textured structure and the isolation layer 20 on the second surface of the N-type silicon substrate 10. The schematic diagram of the BC battery structure is only an example here; other related structures will not be illustrated further.

[0070] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for preparing a BC battery, characterized in that, include: A first region and a second region are formed on a first surface of a silicon substrate in an alternating interdigitated pattern; wherein the doping structures in the first region and the second region are different. The first region and the second region are respectively screen-printed and sintered to form an electrode structure; The second surface of the silicon substrate is texturized, and an isolation layer is formed on the second surface of the silicon substrate to obtain the BC battery; wherein the first surface and the second surface are two mutually opposite surfaces of the silicon substrate, and the isolation layer protrudes from the second surface of the silicon substrate.

2. The preparation method according to claim 1, characterized in that, The material of the insulating layer includes one or any combination of ink, insulating adhesive, hot melt adhesive, PP, PET, EVA or POE.

3. The preparation method according to claim 1, characterized in that, The isolation layer occupies 10%-80% of the area of ​​the second surface.

4. The preparation method according to claim 1, characterized in that, The isolation layer includes multiple protruding structures.

5. The preparation method according to claim 4, characterized in that, Multiple of the protrusions are evenly distributed on one side of the second surface of the silicon substrate.

6. The preparation method according to claim 4, characterized in that, The spacing between any two adjacent protrusions ranges from 0.5mm to 1.5mm.

7. The preparation method according to claim 4, characterized in that, The height of the protrusion structure ranges from 0.1mm to 0.5mm.

8. The preparation method according to claim 1, characterized in that, The isolation layer is transparent.

9. The preparation method according to claim 1, characterized in that, An isolation layer is formed on the second surface of the silicon substrate, comprising: An isolation material is printed on the second surface of the silicon substrate, and the isolation material is cured to form the isolation layer.

10. A BC battery, characterized in that, The BC battery is prepared using the method described in any one of claims 1-9.

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