Solar cell and cell module

Abstract

The utility model is suitable for the field of photovoltaic technology, and provides a solar cell and a cell module. The pyramid structure is arranged on the surface of the silicon substrate; the passivation layer is arranged on the surface of the pyramid structure, the thickness of the passivation layer on the inclined plane of the pyramid structure is a first thickness, the thickness of the passivation layer on the top end of the pyramid structure is a second thickness, and the second thickness is greater than the first thickness. According to the manufacturing method, the sharp defects at the top end of the pyramid structure are eliminated, the situation that cracks are likely to occur at the sharp defects when the photovoltaic cell is subjected to mechanical impact and vibration is avoided, the mechanical load bending strength of the manufactured photovoltaic cell is improved, and the risk that the photovoltaic cell cracks is reduced.

Description

Technical Field

[0001] This application belongs to the field of photovoltaic technology, and in particular relates to a solar cell and a battery module. Background Technology

[0002] A solar cell is a device that converts sunlight into electrical energy. Solar cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thus facilitating the efficient use of electrical energy. Fabricating a textured surface on the solar cell helps to reflect sunlight or other light rays onto the cell surface a second time before absorption and utilization, thereby improving the solar cell's light conversion efficiency. However, after texturing, the pyramidal texture grows in different directions, often forming sharp apex structures at the top of the pyramid. These sharp apex structures are prone to cracking under mechanical impact and vibration, causing damage to the cell surface. Utility Model Content

[0003] This application provides a solar cell designed to address the problem that the cell surface is easily damaged when subjected to mechanical shock and vibration at these sharp, tower-like structures.

[0004] This application is implemented as follows: a solar cell includes: a silicon substrate; a pyramid structure disposed on the surface of the silicon substrate; and a passivation layer disposed on the surface of the pyramid structure, wherein the thickness of the passivation layer on the inclined surface of the pyramid structure is a first thickness, and the thickness of the passivation layer on the top of the pyramid structure is a second thickness, wherein the second thickness is greater than the first thickness.

[0005] Optionally, the ratio of the second thickness to the first thickness is greater than 1 and less than or equal to 5.

[0006] Optionally, the height of the pyramid structure is greater than the second thickness.

[0007] Optionally, the passivation layer has a first protrusion on the slope of the pyramid structure, and / or the passivation layer has a second protrusion at the top of the pyramid structure.

[0008] Optionally, the first protrusion structure is randomly distributed on the passivation layer.

[0009] Optionally, the projected area of ​​the second protrusion along the thickness direction is greater than the projected area of ​​the first protrusion along the thickness direction.

[0010] Optionally, the first protrusion structure and the second protrusion structure are arc-shaped protrusion structures.

[0011] Optionally, the pyramid structure is frustum-shaped or pyramidal.

[0012] Optionally, the angle between the inclined surface of the pyramid structure and the base of the pyramid structure is 20° to 70°.

[0013] Optionally, the inclined surface of the pyramid structure is the surface formed between the apex of the pyramid structure and the bottom edge of the pyramid structure.

[0014] Optionally, the passivation layer between the bottoms of adjacent pyramid structures is a smooth structure.

[0015] Optionally, the height of the pyramid structure is less than 1.5 micrometers.

[0016] This application provides a passivation layer on the surface of a pyramid structure. The passivation layer has a first thickness on the inclined side of the pyramid structure and a second thickness at the top of the pyramid structure, with the second thickness being greater than the first thickness. This enhances the passivation effect at the top of the pyramid structure, eliminates sharp defects at the top of the pyramid structure, and prevents breakage at these sharp defects when subjected to mechanical impact and vibration. This improves the mechanical load bending strength of the manufactured photovoltaic cells and reduces the risk of breakage.

[0017] A battery assembly comprising the aforementioned solar cell. Attached Figure Description

[0018] Figure 1 This is an exemplary cross-sectional schematic diagram of the first type of solar cell provided in this application;

[0019] Figure 2 This is an exemplary cross-sectional schematic diagram of the second type of solar cell provided in this application;

[0020] Figure 3 This is an exemplary cross-sectional schematic diagram of the third type of solar cell provided in this application;

[0021] Figure 4 This is an exemplary top view of the fourth type of solar cell provided in this application.

[0022] Explanation of reference numerals in the attached figures:

[0023] 10. Silicon substrate; 20. Pyramid structure; 30. Passivation layer; 40. First bump structure; 50. Second bump structure. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0025] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0030] like Figure 1 As shown, a solar cell includes a silicon substrate 10 and a pyramid structure 20 disposed on the surface of the silicon substrate 10. A passivation layer is disposed on the surface of the pyramid structure. The thickness of the passivation layer on the inclined surface of the pyramid structure is a first thickness, and the thickness of the passivation layer at the top of the pyramid structure is a second thickness, the second thickness being greater than the first thickness. In this embodiment, the thickness of the passivation layer on the inclined surface of the pyramid structure is the distance between the outer surface of the passivation layer and the inclined surface in a direction perpendicular to the inclined surface of the pyramid structure. The thickness of the passivation layer at the top of the pyramid structure is the distance from the top of the pyramid structure to the top of the passivation layer at the top of the pyramid structure in a direction perpendicular to the base of the pyramid structure. Of course, in actual passivation layer generation, there may be uneven thickness. In this case, the average or maximum value within a unit area can be taken, flexibly selected according to actual measurement needs. This application does not impose any restrictions on this.

[0031] In this embodiment, the pyramid structure 20 can be fabricated by using an alkaline etching solution or anisotropic etching on the silicon substrate 10. The alkaline etching solution comprises a mixed solution of a surfactant, an inhibitor, and at least one of sodium hydroxide, potassium hydroxide, and ammonia. In other embodiments, an acidic etching solution can also be used to etch the surface of the silicon substrate 10. The acidic etching solution comprises a mixed solution of at least one of hydrofluoric acid and nitric acid. It should be noted that the specific type of etching solution used in this application is not particularly limited, and those skilled in the art can choose it arbitrarily according to actual needs, as long as it can meet the etching function.

[0032] In this application, one or more thin films, such as SiNx films, SiO2 films, SiO2 / SiNx stacked films, or Al2O3 films, are deposited on the surface of the pyramid structure 20 using PECVD, thermal oxidation, atomic layer deposition (ALD), etc., for passivation. A passivation layer 30 is formed on the inclined surface and at the top of the pyramid structure 20. This passivation layer effectively reduces defects and impurities on the surface of the solar cell, thereby reducing recombination centers and improving photoelectric conversion efficiency. Furthermore, the second thickness is greater than the first thickness. This approach enhances the passivation effect at the top of the pyramid structure 20, eliminates sharp defects at the top, and prevents breakage at these sharp defects when subjected to mechanical impact and vibration. This improves the mechanical load bending strength of the manufactured photovoltaic cell and reduces the risk of breakage. On the other hand, the top of the pyramid structure 20 is usually a sharp area where passivation treatment is less effective, easily forming passivation defects and recombination centers, which affect carrier transport. This application improves the passivation effect of the sharp part at the top of the pyramid structure 20 by setting a thicker passivation film layer, thus preventing leakage current.

[0033] Specifically, the slope of the pyramid structure 20 is the surface formed between the apex and the base of the pyramid structure 20. Understandably, the pyramid structure 20 has multiple slopes, each with a passivation layer 30. Since the slopes of the pyramid structure 20 are relatively flat, a thick passivation layer is sufficient to achieve a good passivation effect; the thickness of the passivation layer 30 can be between 50-100 nm. The apex of the pyramid structure 20 is a sharp portion. Preferably, the ratio of the second thickness to the first thickness is greater than 1 and less than or equal to 5. The thickness of the passivation layer at the pyramid apex is several times greater than the thickness on the slopes of the pyramid, greatly enhancing the passivation of the apex of the pyramid structure 20. This ensures the passivation quality of the apex of the pyramid structure 20, making the apexes of multiple pyramid structures 20 more consistent and smooth, thus improving the light-trapping effect on the surface of the solar cell.

[0034] In some embodiments, the height of the pyramid structure is greater than the second thickness. A greater pyramid height implies a deeper light-trapping structure, enabling more efficient capture and utilization of incident light, reducing light reflection and scattering losses. Furthermore, the passivation layer helps reduce surface recombination, and its thickness, when small relative to the pyramid height, does not significantly affect the pyramid's light-trapping effect. When the pyramid height is greater than the passivation layer thickness, the passivation layer can more effectively cover the top and sides of the pyramid, creating a more uniform passivation effect, thereby reducing the number of surface recombination centers.

[0035] In this embodiment, preferably, the height of the pyramid structure 20 is less than 1.5 micrometers. No specific limitation is imposed here. A pyramidal textured surface formed by the height of the pyramid structure 20 within this range can generate a passivation layer with good film quality, resulting in better passivation of the cell surface and reducing the possibility of leakage current.

[0036] like Figure 2 and Figure 3 As shown, in some embodiments, the pyramid structure 20 is frustum-shaped or pyramidal (illustrated by lines in the figure). Different etching methods form pyramid structures 20 with different structures, and this application does not impose any limitations on the comparison. Specifically, when the pyramid structure 20 is frustum-shaped, the top of the pyramid is a planar structure; when the pyramid is pyramidal, the top of the pyramid is a pointed structure.

[0037] like Figure 4 As shown, in some embodiments, the angle between the inclined surface of the pyramid structure 20 and the base of the pyramid structure 20 is 20° to 70°. In this application, the angle between the inclined surface of the pyramid structure 20 and the base of the pyramid structure 20 is the angle between the side surface of the frustum and the bottom surface of the frustum, and the angle between the inclined surface of the pyramid structure 20 and the base of the pyramid structure 20 is the angle between the side surface of the pyramid and the base of the pyramid. Specifically, with the preferred angle between the inclined surface and the base, on the one hand, the surface of the solar cell has a lower reflectivity, further improving the light conversion efficiency of the solar cell; on the other hand, the transition between multiple pyramid structures 20 can be smooth, forming a better passivation layer. Preferably, the passivation layer between the bases of adjacent pyramid structures 20 is a smooth structure, thereby forming a relatively smooth pyramid textured structure on the surface of the solar cell, which facilitates the subsequent formation of a high-quality anti-reflection film on the surface of the solar cell.

[0038] Furthermore, the passivation layer 30 may include at least one or a combination of multiple of the following: an aluminum oxide film layer, a silicon oxide film layer, a silicon nitride film layer, a silicon carbide film layer, and a silicon oxynitride film layer. For example, in some embodiments, the passivation layer 30 may include an aluminum oxide film layer and a silicon nitride film layer stacked sequentially, and the specific details are not limited herein.

[0039] In this embodiment, the passivation layer has a first protrusion structure 40 on the inclined surface of the pyramid structure, and / or a second protrusion structure 50 at the top of the pyramid structure. The first protrusion structure 40 is randomly distributed on the passivation layer 30, and optionally, the second protrusion structure 50 is also randomly distributed on the passivation layer 30. This increases the specific surface area of ​​the passivation layer 30, enhances the light-trapping effect on the surface of the solar cell, and thus improves the power generation efficiency of the solar cell.

[0040] Furthermore, the projected area of ​​the second protrusion 50 along the thickness direction is larger than that of the first protrusion 40 along the thickness direction. This further increases the specific surface area at the top of the pyramid structure, thereby enhancing the light-trapping effect on the surface of the solar cell. Preferably, the first protrusion 40 and the second protrusion 50 are arc-shaped protrusion structures. Compared with planar structures, arc-shaped protrusion structures can better match the angle of incident light, reduce direct reflection of light at the interface, improve light utilization, and guide light through multiple reflections and scatterings within the material through their geometric characteristics, thereby extending the optical path and improving light absorption efficiency. In addition, in the existing pyramid structure 20, there are fine cracks on the inclined surface of the pyramid structure 20. These cracks are essentially recessed on the inclined surface of the pyramid structure 20. These recessed cracks easily hide debris and are inconvenient for subsequent cleaning of the solar cell. In this application, the passivation layer 30 on the slope of the pyramid structure 20 has a first protrusion structure 40 and the passivation layer at the top of the pyramid has a second protrusion structure 50. That is, the first protrusion structure 40 protrudes from the surface of the passivation layer 30 on the slope, and the second protrusion structure 50 protrudes from the surface of the passivation layer 30 at the top of the pyramid structure. While ensuring the pyramid textured surface structure with low reflectivity, it is also beneficial for subsequent cleaning of the solar cells.

[0041] It should be noted that when the tip of the pyramid structure 20 is ground flat or modified into an arc shape in the subsequent process, the tip of the pyramid structure 20 is determined by the extension line of the corresponding edge of the pyramid structure 20, and thus the slope of the pyramid structure 20 can be determined.

[0042] Therefore, when the pyramid structure 20 is a pyramid with a protrusion, the inclined surface of the pyramid structure 20 is the surface formed by the vertex of the pyramid and the base of the pyramid; when the pyramid structure 20 is a frustum with a protrusion, the inclined surface of the pyramid structure 20 is the surface formed by the upper base of the frustum with a protrusion and the corresponding lower base.

[0043] A battery assembly includes the aforementioned solar cell. Based on the described solar cell, those skilled in the art will understand that a corresponding battery assembly can be obtained using multiple such solar cells and / or other corresponding existing accessories.

[0044] In this embodiment, multiple solar cells in the battery module can be connected in series to form a battery string, thereby achieving series current collection and output. For example, the series connection of the cells can be achieved by setting solder strips (busbars, interconnecting strips), conductive backsheets, etc. It is understood that in such an embodiment, the battery module may also include a metal frame, a backsheet, photovoltaic glass, and an encapsulating film. The encapsulating film can be filled between the front and back of the back contact cells, the photovoltaic glass, adjacent cells, etc. As a filler, it can be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film can be EVA film or POE film, and the specific choice can be made according to the actual situation, without limitation.

[0045] In the description of this specification, the use of terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., refers to specific features, structures, materials, or characteristics described in connection with the embodiments or examples, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0046] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A solar cell, characterized in that, include: silicon substrate; A pyramid structure disposed on the surface of the silicon substrate; A passivation layer is disposed on the surface of the pyramid structure. The passivation layer has a first thickness on the inclined surface of the pyramid structure and a second thickness at the top of the pyramid structure. The second thickness is greater than the first thickness. The passivation layer includes an aluminum oxide film layer and a silicon nitride film layer stacked sequentially.

2. The solar cell as described in claim 1, characterized in that, The ratio of the second thickness to the first thickness is greater than 1 and less than or equal to 5.

3. The solar cell as described in claim 1, characterized in that, The height of the pyramid structure is greater than the second thickness.

4. The solar cell as described in claim 1, characterized in that, The passivation layer has a first protrusion on the slope of the pyramid structure, and / or the passivation layer has a second protrusion at the top of the pyramid structure.

5. The solar cell as described in claim 4, characterized in that, The first protrusion structure is randomly distributed on the passivation layer.

6. The solar cell as described in claim 4, characterized in that, The projected area of ​​the second protrusion along the thickness direction is greater than the projected area of ​​the first protrusion along the thickness direction.

7. The solar cell as claimed in claim 4, characterized in that, The first protrusion structure and the second protrusion structure are arc-shaped protrusion structures.

8. The solar cell as claimed in claim 1, characterized in that, The pyramid structure is frustum-shaped or pyramidal.

9. The solar cell according to claim 1, characterized in that, The angle between the inclined plane of the pyramid structure and the base of the pyramid structure is 20° to 70°.

10. The solar cell according to claim 1, characterized in that, The sloping surface of the pyramid structure is the surface formed between the pyramid's apex and the base of the pyramid structure.

11. The solar cell according to claim 1, characterized in that, The passivation layer between the bottoms of adjacent pyramid structures has a smooth structure.

12. The solar cell according to claim 1, characterized in that, The height of the pyramid structure is less than 1.5 micrometers.

13. A battery assembly, characterized in that, The solar cell includes any one of claims 1-12 above.

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