Solar cell
By introducing a stepped surface structure and a multi-layer passivation layer design into solar cells, the problems of dangling bonds affecting conversion efficiency and high cost of passivation layers are solved, achieving a more efficient passivation effect and reduced cost.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- CHINT NEW ENERGY TECH CO LTD
- Filing Date
- 2025-08-13
- Publication Date
- 2026-07-30
AI Technical Summary
Existing solar cells have dangling bonds on the cut surface, which affects conversion efficiency, and the existing passivation layer is thick, resulting in high cost.
By adopting a stepped surface structure and combining the design of a first passivation layer and a second passivation layer, the first passivation layer covers the emitter side, and the second passivation layer covers the first passivation layer on both the substrate side and the emitter side, forming a multi-layer passivation layer, which optimizes the passivation effect and reduces costs.
The passivation effect was enhanced, the thickness requirement of the passivation layer was reduced, thereby reducing costs, while the emitter side was given special protection.
Smart Images
Figure CN2025114383_30072026_PF_FP_ABST
Abstract
Description
A solar cell
[0001] This application claims priority to Chinese Patent Application No. 202520156369.5, filed on January 22, 2025, entitled "A Solar Cell", the entire contents of which are incorporated herein by reference. Technical Field
[0002] This application relates to the field of photovoltaic technology, and in particular to a solar cell. Background Technology
[0003] During the fabrication of solar cells, the cells need to be cut into two-piece, four-piece, or similar shapes depending on their size and specifications. However, this cutting process leaves the cells with cut surfaces. Since these cut surfaces contain numerous dangling bonds, they can affect the cell's conversion efficiency; therefore, strong passivation is required to protect these surfaces.
[0004] To address the aforementioned issues, ASP (Advanced Surface Passivation Technology) was proposed. This technology first uses a laser to slice the entire solar cell, creating cut surfaces on the sides. Then, a passivation film is applied to passivate these cut surfaces. Because it effectively repairs microscopic damage, it can reduce passivation losses, thereby improving the conversion efficiency of the cell and module. Among these technologies, TOPCon (Tunnel Oxide Passivating Contact) primarily repairs and protects against cut damage to the emitter (PN junction). Currently, the mainstream thickness of the side passivation layer is 50nm–100nm, resulting in high costs. Therefore, how to enhance passivation effectiveness while reducing costs is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention
[0005] In view of this, the purpose of this application is to provide a solar cell that enhances passivation while reducing cost.
[0006] To address the aforementioned technical problems, this application provides a solar cell, comprising: a substrate; an emitter disposed on the surface of the substrate; a stepped surface at least partially formed on the side surface of the substrate; the side surface of the stepped surface at least includes the side surface of the emitter; the ratio of the height H of the side surface of the stepped surface to the sum of the thicknesses of the emitter and the substrate is 1:1.5 to 1:300, including the values at both ends;
[0007] A first passivation layer is disposed on the surface of the emitter away from the substrate; the first passivation layer extends to the step surface;
[0008] A second passivation layer is provided on the surface of the first passivation layer covering the side of the emitter and on the side of the substrate not covered by the first passivation layer.
[0009] Optionally, the thickness of the second passivation layer is 5 nm to 50 nm, including the values at both ends; and / or,
[0010] The ratio of the height H of the side of the stepped surface to the sum of the thicknesses of the emitter and the substrate is 1:2 to 1:80, including the values at both ends.
[0011] Optionally, the thickness of the first passivation layer is less than 10 nm; and / or,
[0012] The width of the emitter is smaller than the width of the substrate; and / or,
[0013] The first passivation layer extends to the bottom surface of the stepped surface.
[0014] Optionally, the height H of the side surface of the stepped surface is greater than the thickness of the emitter.
[0015] Optionally, the height H of the side surface of the step is 0.5μm to 100μm, including the values at both ends;
[0016] And / or, the width D of the bottom surface of the step surface is 0.05μm to 50μm, including the values at both ends;
[0017] And / or, the thickness of the emitter is 1 μm to 2 μm, including the values at both ends.
[0018] Optionally, one end of the second passivation layer extends to the surface of the first passivation layer away from the emitter and covers a portion of the surface of the first passivation layer; the other end of the second passivation layer extends to the surface of the substrate away from the emitter and covers a portion of the surface of the substrate.
[0019] Optionally, the first passivation layer includes AlO. x layer;
[0020] And / or, the second passivation layer comprises AlO x At least one of the following: a silicon nitride layer, a silicon oxynitride layer, an aluminum nitride layer, and an aluminum oxynitride layer.
[0021] Optionally, an anti-reflection layer is provided on the surface of the first passivation layer away from the emitter.
[0022] Optionally, the antireflective layer includes at least one of a silicon nitride layer and a silicon oxynitride layer;
[0023] And / or, the thickness of the antireflective layer is 80nm to 90nm, including the values at both ends;
[0024] And / or, the antireflection layer is sandwiched between the first passivation layer and the second passivation layer.
[0025] Optionally, the side surface of the stepped surface includes the side surface of the emitter and a portion of the side surface of the substrate.
[0026] As can be seen, the solar cell provided in this application includes: a substrate; an emitter disposed on the surface of the substrate; a stepped surface formed on the side of the substrate; the side of the stepped surface at least includes the side of the emitter; the ratio of the height H of the side of the stepped surface to the sum of the thicknesses of the emitter and the substrate is 1:1.5 to 1:300, including both ends; a first passivation layer disposed on the surface of the emitter away from the substrate; the first passivation layer extending to the stepped surface; a second passivation layer disposed on the surface of the first passivation layer covering the side of the emitter and on the side of the substrate not covered by the first passivation layer.
[0027] The height of the side of the stepped surface in this application has a suitable ratio to the sum of the thicknesses of the emitter and the substrate to ensure the coverage of the passivation layer. A first passivation layer is provided on the surface of the emitter, extending to cover the side of the emitter. A second passivation layer is provided on the side of the substrate, covering both the first passivation layer on the side of the substrate and the side of the emitter. This forms a multi-layer passivation layer on the side of the emitter, providing key protection for the emitter side. Since the first passivation layer is already provided on the side of the emitter, the second passivation layer does not need to be thick, thus enhancing the passivation effect and reducing costs. Attached Figure Description
[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0029] Figure 1 is a schematic diagram of a solar cell provided in an embodiment of this application;
[0030] Figures 2 to 4 are schematic diagrams of the fabrication process of a solar cell provided in the embodiments of this application.
[0031] The reference numerals in the attached figures are explained as follows: 1-Substrate; 2-Emitter; 3-Initial trench; 4-First passivation layer; 5-Cut groove; 6-Second passivation layer. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0033] Please refer to Figure 1, which is a schematic diagram of a solar cell structure provided in an embodiment of this application. The solar cell may include: a substrate 1; an emitter 2 disposed on the surface of the substrate 1; a stepped surface at least partially formed on the side of the substrate 1; the side of the stepped surface at least includes the side of the emitter 2; the ratio of the height H of the side of the stepped surface to the sum of the thicknesses of the emitter 2 and the substrate 1 is 1:1.5 to 1:300, including the values at both ends;
[0034] A first passivation layer 4 is disposed on the surface of the emitter 2 away from the substrate 1; the first passivation layer 4 extends to the step surface;
[0035] A second passivation layer 6 is provided on the surface of the first passivation layer 4 covering the side of the emitter 2 and on the side of the substrate 1 not covered by the first passivation layer 4.
[0036] Preferably, in this embodiment, the ratio of the height H of the side surface of the step surface to the total thickness of the emitter and the substrate can be 1:2 to 1:80, including both ends. It should be noted that by using the above-mentioned range for the ratio of the height H of the side surface of the step surface to the total thickness of the emitter 2 and the substrate 1, it can be ensured that the height H of the side surface of the step surface is not less than the thickness of the emitter 2, so that when the first passivation layer 4 extends to the bottom surface of the step surface, it can completely cover the side surface of the emitter 2. Furthermore, it should be noted that in this embodiment, the length direction of the step surface is parallel to the length of the cut surface. However, since the step surface is formed by etching, the etching rate of different materials will be different during the etching process, resulting in differences in the etching morphology of different parts and different materials. Due to the influence of the process, the step surface may be irregular. Preferably, in this embodiment, the height H of the side surface of the step surface is in a direction perpendicular to the length of the cut surface, that is, the height H of the side surface of the step surface is parallel to the height of the cut surface; and the height H of the side surface of the step surface is the average value of the distances from various positions on the bottom surface of the step surface to the side surface of the emitter 2 facing away from the substrate 1.
[0037] This embodiment does not limit the specific type of substrate 1. Substrate 1 can be, but is not limited to, a silicon substrate. It should be noted that silicon is a common material in the prior art. This embodiment does not limit the internal composition of substrate 1, but directly uses a silicon substrate made of existing materials.
[0038] This embodiment does not limit the specific thickness of the first passivation layer 4. For example, the thickness of the first passivation layer 4 can be less than 10 nm. To achieve the best passivation effect, the preferred thickness of the first passivation layer 4 in this embodiment can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, or 9 nm. This embodiment does not limit the specific type of the first passivation layer 4, as long as the passivation effect is achieved. For example, the first passivation layer 4 may include AlO2. x Layer. It should be noted that AlO x The layer is a common material in the prior art. In this embodiment, the internal composition of the first passivation layer 4 is not limited, but a film layer made of existing materials is directly used as the first passivation layer 4.
[0039] To achieve the best passivation effect, the preferred first passivation layer 4 in this embodiment can extend to the bottom surface of the step surface.
[0040] Furthermore, to reduce light reflection, an anti-reflection layer can be provided on the surface of the first passivation layer 4 away from the emitter 2 in this embodiment. When one end of the second passivation layer 6 extends to the surface of the first passivation layer 4 away from the emitter 2, the anti-reflection layer in this embodiment can be sandwiched between the first passivation layer 4 and the second passivation layer 6. This embodiment does not limit the specific thickness of the anti-reflection layer; for example, the thickness of the anti-reflection layer can be 80nm to 90nm, including both ends. To achieve the best anti-reflection effect, the preferred thickness of the anti-reflection layer in this embodiment can be 80nm, 81nm, 82nm, 83nm, 84nm, 85nm, 86nm, 87nm, 88nm, 89nm, or 90nm. This embodiment does not limit the specific type of anti-reflection layer, as long as it can reduce light reflection. For example, the anti-reflection layer can include at least one of silicon nitride layer and silicon oxynitride layer. It should be noted that silicon nitride layer and silicon oxynitride layer are common materials in the prior art. This embodiment does not limit the internal composition of the anti-reflection layer, but directly uses a film layer made of existing materials as the anti-reflection layer.
[0041] This embodiment does not limit the specific thickness of the second passivation layer 6. For example, the thickness of the second passivation layer 6 can be 5nm to 50nm, including the values at both ends. To achieve the best passivation effect, the preferred thickness of the second passivation layer 6 in this embodiment can be 5nm, 6nm, 7nm, 8nm, 9nm...48nm, 49nm or 50nm. It should be noted that the thickness of the passivation layer on the cut surface in traditional solar cells is 50nm to 100nm. However, in this embodiment, since the first passivation layer 4 is already provided on the side of the emitter 2, the second passivation layer 6 does not need to be thick. Here, "not needing to be thick" is relative to the passivation layer thickness of traditional solar cells.
[0042] This embodiment does not limit the specific type of the second passivation layer 6, as long as the passivation effect can be achieved. For example, the second passivation layer 6 may include AlO. x At least one of the following: AlO layer, silicon nitride layer, silicon oxynitride layer, aluminum nitride layer, and aluminum oxynitride layer. It should be noted that AlO x The layers, silicon nitride layer, silicon oxynitride layer, aluminum nitride layer and aluminum oxynitride layer are common materials in the prior art. This embodiment does not limit the internal composition of the second passivation layer 6, but directly uses a film layer made of existing materials as the second passivation layer 6.
[0043] Furthermore, in order to enhance the passivation effect, in this embodiment, one end of the second passivation layer 6 can extend to the surface of the first passivation layer 4 away from the emitter 2 and cover part of the surface of the first passivation layer 4; the other end of the second passivation layer 6 can extend to the surface of the substrate 1 away from the emitter 2 and cover part of the surface of the substrate 1.
[0044] It should be noted that, in this embodiment, to ensure that the extended portion of the first passivation layer 4 completely covers the side surface of the emitter 2, the height H of the side surface of the step surface must not be less than the thickness of the emitter 2. Specifically, when the height H of the side surface of the step surface is equal to the thickness of the emitter 2, in this embodiment, the side surface of the step surface only includes the side surface of the emitter 2, and the extended portion of the first passivation layer 4 only covers the side surface of the emitter 2; when the height H of the side surface of the step surface is greater than the thickness of the emitter 2, in this embodiment, the side surface of the step surface may include the side surface of the emitter 2 and part of the side surface of the substrate 1, and in this embodiment, the extended portion of the first passivation layer 4 can cover both the side surface of the emitter 2 and part of the side surface of the substrate 1. It should be noted that, in this embodiment, when the height H of the side surface of the step surface is greater than the thickness of the emitter 2, the protection effect of the extended portion of the first passivation layer 4 on the side surface of the emitter 2 is optimal.
[0045] This embodiment does not limit the specific number of stepped surfaces. The specific number of cut surfaces can be determined according to the actual cutting method. For example, when the solar cell is obtained by one cut, a stepped surface can be formed on one side of the substrate 1. At this time, one side of the substrate 1 is aligned with the emitter 2, and the other side extends beyond the emitter 2. When the solar cell is obtained by two cuts, stepped surfaces can be formed on opposite sides of the substrate 1. This application does not limit the cutting method of the solar cell.
[0046] This application provides an embodiment of a cutting method in which the battery cell is laser-cut on opposite sides, forming two cutting grooves on opposite sides of the battery cell surface. The two cutting grooves are located on the same straight line L1, and thermal stress cleaving is performed along line L1 to divide the battery cell into two pieces. The cleaved side of the battery cell is the cut surface of the divided battery cell. After thermal stress cleaving, a stepped surface is formed at the location of the cutting grooves. In this embodiment, the cut surface of the battery cell has a partially stepped surface.
[0047] In another embodiment of the cutting method provided in this application, laser cutting is performed along a straight line L2 on the surface of the battery cell to form a cutting groove. Thermal stress splitting is then performed along the cutting groove to divide the battery cell into two pieces. The split side of the battery cell forms the cut surface of the divided battery cell. After thermal stress splitting at the cutting groove location, a stepped surface is formed. In this embodiment, the stepped surface of the battery cell extends along the length of the cut surface and from one end of the cut surface to the other.
[0048] In the embodiments of this application, at least one side is a cut surface, that is, at least one side of the battery cell of this application has a stepped surface, and the side may have a partial stepped surface. The stepped surface may also extend along the length direction of the side and extend from one end of the side to the other end.
[0049] This embodiment does not limit the specific height of the side surface of the step surface, as long as the height H of the side surface of the step surface is greater than the thickness of the emitter 2. For example, the height H of the side surface of the step surface can be 0.5μm to 100μm, including the values at both ends. To achieve the best protection effect, the preferred side surface height H of the step surface in this embodiment can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm…99.8μm, 99.9μm or 100μm. This embodiment does not limit the specific width of the bottom surface of the step surface. For example, the width D of the bottom surface of the step surface can be 0.05μm to 50μm, including the values at both ends. To achieve the best protection effect, the preferred bottom surface width D of the step surface in this embodiment can be 0.05μm, 0.06μm, 0.07μm, 0.08μm, 0.09μm…49.98μm, 49.99μm or 50μm. It should be noted that after the first passivation layer 4 is provided on the side of the step surface, it can be flush with the side of the substrate 1 or not exceed the side of the substrate 1. This can be determined according to the specific width of the bottom surface of the step surface, the specific thickness of the first passivation layer 4, and the specific thickness of the anti-reflection layer.
[0050] To achieve optimal passivation, the width of the emitter 2 in this embodiment is preferably smaller than the width of the substrate 1. It should be noted that when the stepped surface is located on the cut surface, the width directions of the emitter 2 and the substrate 1 in this embodiment should be perpendicular to the height of the cut surface. This embodiment does not limit the specific thickness of the emitter 2, as long as the thickness of the emitter 2 is less than the height H of the side of the stepped surface. For example, the thickness of the emitter 2 can be 1μm to 2μm, including the values at both ends. In this embodiment, the preferred thickness of the emitter 2 can be 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, or 2μm.
[0051] In addition to the substrate 1, emitter 2, first passivation layer 4, and second passivation layer 6, this embodiment may include other structures, which can be determined according to the specific type of solar cell. This embodiment does not limit the specific type of solar cell; for example, the solar cell may be a TOPCon cell. This embodiment does not limit the specific structure of the TOPCon cell; specific details can be found in existing TOPCon cells, which will not be elaborated here. This embodiment does not limit the specific surface on which the emitter is disposed; the specific surface can be determined according to the specific type of solar cell. For example, when the solar cell is a TOPCon cell, the emitter 2 can be disposed on the front side of the substrate 1.
[0052] Based on the above embodiments, the height of the side surface of the stepped surface in this application has a suitable ratio to the sum of the thicknesses of the emitter and the substrate to ensure the coverage of the passivation layer. A first passivation layer is provided on the surface of the emitter, extending to cover the side surface of the emitter. A second passivation layer is provided on the side surface of the substrate, covering both the first passivation layer on the side surface of the substrate and the side surface of the emitter. This forms a multi-layer passivation layer on the side surface of the emitter, providing key protection for the emitter side surface. Since a first passivation layer has already been provided on the side surface of the emitter, the second passivation layer does not need to be thick, thus enhancing the passivation effect and reducing costs.
[0053] To facilitate understanding of this application, please refer to Figures 1 to 4. An embodiment of this application provides a fabrication process for a solar cell, which specifically includes:
[0054] 1. As shown in Figure 2, an emitter 2 is formed on the front side of the substrate 1, and the width of the emitter 2 is equal to the width of the substrate 1. After the emitter 2 is formed, a trench is created. In this embodiment, the initial trench 3 formed penetrates the emitter 2 and part of the substrate 1 along the thickness direction, or it can penetrate only the emitter 2 along the thickness direction. In this embodiment, only one initial trench 3 is formed, or at least two initial trenches 3 can be formed. The width of the initial trench 3 can be 0.1μm to 100μm, including the values at both ends. The depth of the initial trench 3 can be 0.5μm to 100μm, including the values at both ends. It should be noted that in this embodiment, the width of the initial trench 3 is greater than the width of the bottom surface of the step surface. Preferably, the width of the bottom surface of the step surface is equal to 1 / 2 the width of the initial trench 3. The height of the initial trench 3 is equal to the height of the side surface of the step surface. In this embodiment, the trench is created on the surface of the emitter 2 after the emitter 2 is formed, so the emitter 2 does not extend into the initial trench 3.
[0055] 2. As shown in Figure 3, after the initial trench 3 is formed, a first passivation layer 4 is formed on the surface of the emitter 2 away from the substrate 1. The first passivation layer 4 covers the surface of the emitter 2 away from the substrate 1 and also covers the inner surface of the initial trench 3. The new trench formed after the inner surface of the initial trench 3 is covered by the first passivation layer 4 is the dicing groove 5. In this embodiment, only one dicing groove 5 is formed, but at least two dicing grooves 5 can also be formed. After the first passivation layer 4 is formed, metallization is performed to form a gate line (not shown in the figure).
[0056] 3. As shown in Figure 4, after metallization, the substrate 1 is cut (or split) at the cutting groove 5 to obtain a single solar cell. When there is only one cutting groove 5, the substrate 1 of the obtained single solar cell has a stepped surface on only one side. When there are at least two cutting grooves 5, the obtained single solar cell has two cases: the first is a solar cell with a stepped surface on only one side of the substrate 1, and the second is a solar cell with stepped surfaces on both opposite sides of the substrate 1.
[0057] 4. As shown in Figure 1, a second passivation layer 6 is formed on the cut surface of a single solar cell, so that the second passivation layer 6 covers the surface of the first passivation layer 4 on the side of the emitter 2 and the side of the substrate 1 not covered by the first passivation layer 4. At the same time, the second passivation layer 6 is deposited around the surface of the first passivation layer 4 away from the emitter 2 and the back surface of the substrate 1, so that one end of the second passivation layer 6 covers part of the surface of the first passivation layer 4 away from the emitter 2, and the other end covers part of the back surface of the substrate 1.
[0058] Using the solar cell fabrication process provided in the embodiments of this application, the solar cell fabricated includes: a substrate 1; an emitter 2 disposed on the front side of the substrate 1; the width of the emitter 2 is smaller than the width of the substrate 1, and a stepped surface is formed on one side of the substrate 1; the side of the stepped surface includes the side of the emitter 2 and a portion of the side of the substrate 1; a first passivation layer 4 disposed on the surface of the emitter 2 away from the substrate 1; the first passivation layer 4 extends to the bottom surface of the stepped surface; a second passivation layer 6 is disposed on the surface of the first passivation layer 4 covering the side of the emitter 2 and the side of the substrate 1 not covered by the first passivation layer 4; one end of the second passivation layer 6 extends to the surface of the first passivation layer 4 away from the emitter 2 and covers a portion of the surface of the first passivation layer 4; the other end of the second passivation layer 6 extends to the back side of the substrate 1 and covers a portion of the back side of the substrate 1.
[0059] This application first sets a first passivation layer 4 on the surface of the emitter 2, extending the first passivation layer 4 to cover the side of the emitter 2, and then sets a second passivation layer 6 on the side of the substrate 1, so that the second passivation layer 6 simultaneously covers the first passivation layer 4 on both the side of the substrate 1 and the side of the emitter 2, thereby forming a multi-layer passivation layer on the side of the emitter 2, providing key protection for the side of the emitter 2. At the same time, since the first passivation layer 4 has already been set on the side of the emitter 2, the second passivation layer 6 does not need to be thick, so it can both enhance the passivation effect and reduce costs.
[0060] The above provides a detailed description of a solar cell provided in this application. For those skilled in the art, based on the ideas of the embodiments of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.