Solar cell and cell module

Abstract

The invention 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] The present application belongs to the field of photovoltaic technology, and in particular to a solar cell and a battery assembly. Background Art

[0002] Solar cells are devices that convert sunlight into electrical energy. Solar cells use the photovoltaic principle to generate carriers, and then use electrodes to lead out the carriers, which is conducive to the effective use of electrical energy. Preparing a velvet structure on the surface of a solar cell helps to absorb and utilize sunlight or other light that hits the surface of the cell after secondary reflection, thereby improving the light conversion efficiency of the solar cell. After velveting, the growth direction of the pyramid velvet varies, and it is easy to form a sharp spire structure at the top of the pyramid. When subjected to mechanical shock and vibration, these sharp spire structures are prone to rupture, causing damage to the surface of the cell.

[0003] Application Contents

[0004] The present application provides a solar cell, aiming to solve the problem that these sharp spire structures are prone to breakage when subjected to mechanical shock and vibration, causing damage to the surface of the solar cell.

[0005] The present application is implemented as follows: a solar cell includes: a silicon substrate; a pyramid structure arranged on the surface of the silicon substrate; a passivation layer arranged 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, the thickness of the passivation layer on the top of the pyramid structure is a second thickness, and the second thickness is greater than the first thickness.

[0006] Optionally, a ratio of the second thickness to the first thickness is greater than 1 and less than or equal to 5.

[0007] Optionally, the tower height of the pyramid structure is greater than the second thickness.

[0008] Optionally, the passivation layer has a first protruding structure on the inclined surface of the pyramid structure, and / or the passivation layer has a second protruding structure on the top of the pyramid structure.

[0009] Optionally, the first protrusion structures are randomly distributed on the passivation layer.

[0010] Optionally, a projection area of ​​the second protruding structure along the thickness direction is larger than a projection area of ​​the first protruding structure along the thickness direction.

[0011] Optionally, the first protruding structure and the second protruding structure are arc-shaped protruding structures.

[0012] Optionally, the pyramid structure is in the shape of a prism or a pyramid.

[0013] Optionally, an angle between the inclined surface of the pyramid structure and the base of the pyramid structure is 20° to 70°.

[0014] Optionally, the inclined surface of the pyramid structure is a surface formed between the top of the pyramid structure and the bottom edge of the bottom of the pyramid structure.

[0015] Optionally, the passivation layer between the bottoms of adjacent pyramid structures is a smooth structure.

[0016] Optionally, the height of the pyramid structure is less than 1.5 microns.

[0017] The present application sets a passivation layer 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, and the second thickness is greater than the first thickness, thereby strengthening the passivation effect of the top of the pyramid structure, eliminating the sharp defects at the top of the pyramid structure, and avoiding the occurrence of rupture at these sharp defects when subjected to mechanical shock and vibration, thereby improving the mechanical load bending strength of the prepared photovoltaic cell and reducing the risk of rupture of the photovoltaic cell.

[0018] A battery assembly comprises the above-mentioned solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is an exemplary cross-sectional schematic diagram of the first solar cell provided in the present application;

[0020] Figure 2 is an exemplary cross-sectional schematic diagram of the second solar cell provided in the present application;

[0021] Figure 3 is an exemplary cross-sectional schematic diagram of a third solar cell provided in the present application;

[0022] Figure 4 1 is an exemplary top view schematic diagram of the fourth solar cell provided in the present application.

[0023] Description of reference numerals:

[0024] 10. Silicon substrate; 20. Pyramid structure; 30. Passivation layer; 40. First protruding structure; 50. Second protruding structure. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below 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 throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0026] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0029] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0030] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0031] like Figure 1 As shown, a solar cell includes a silicon substrate 10 and a pyramid structure 20 arranged on the surface of the silicon substrate 10, a passivation layer arranged 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 on the top of the pyramid structure is a second thickness, and the second thickness is greater than the first thickness. In the embodiment of the present application, 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 the 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 the direction perpendicular to the base of the pyramid structure. Of course, in the actual generation of the passivation layer, there is a situation where the thickness is uneven. At this time, the average value or maximum value within the unit area can be taken, and it can be flexibly selected according to the actual measurement needs, and the present application does not limit this.

[0032] In the embodiment of the present application, for example, the silicon substrate 10 can be etched with an alkaline etching solution or anisotropically to form the pyramid structure 20, and the alkaline etching solution includes a mixed solution formed by a surfactant and an inhibitor and at least one of sodium hydroxide, potassium hydroxide, and ammonia water. In other embodiments, an acidic etching solution can also be used to etch the surface of the silicon substrate 10, and the acidic etching solution includes a mixed solution of at least one of hydrofluoric acid and nitric acid. It should be noted that the specific type of etching solution of the present application is not particularly limited, and those skilled in the art can choose it at will according to actual needs, as long as it can meet the etching function.

[0033] In the present application, one or more thin films, such as SiNx film, SiO2 film, SiO2 / SiNx laminated film or Al2O3 film, are deposited on the surface of the pyramid structure 20 by PECVD, thermal oxidation, atomic layer deposition (ALD) or the like for passivation, and a passivation layer 30 is formed on the inclined surface of the pyramid structure 20 and on the top of the pyramid structure 20. The passivation layer can effectively reduce defects and impurities on the surface of the cell, thereby reducing recombination centers, thereby improving the photoelectric conversion efficiency. In addition, the second thickness is greater than the first thickness. On the one hand, this can enhance the passivation effect of the top of the pyramid structure 20, eliminate the sharp defects at the top of the pyramid structure 20, and avoid rupture at these sharp defects when subjected to mechanical shock and vibration, thereby improving the mechanical load bending strength of the prepared photovoltaic cell and reducing the risk of rupture of the photovoltaic cell. On the other hand, the top of the pyramid structure 20 is usually a sharp area, so the passivation treatment effect is poor, and it is easy to form passivation defects and form recombination centers, which affect the transmission of carriers. The present application can improve the passivation effect of the sharp part of the top of the pyramid structure 20 by setting a thicker passivation film layer at the top of the pyramid structure 20, thereby avoiding the generation of leakage current.

[0034] Specifically, the inclined surface of the pyramid structure 20 is a surface formed between the top of the pyramid structure 20 and the bottom edge of the bottom of the pyramid structure 20. It can be understood that there are multiple inclined surfaces of the pyramid structure 20, and a passivation layer 30 is set on each inclined surface. Since the inclined surface of the pyramid structure 20 is relatively flat, a better passivation effect can be formed without setting a thicker passivation layer. The thickness of the passivation layer 30 can be between 50-100nm. The top of the pyramid structure 20 is a sharp part. 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 top of the pyramid is increased by multiples of the thickness of the passivation layer at the inclined surface of the pyramid, which greatly enhances the passivation of the top of the pyramid structure 20, thereby ensuring the passivation quality of the top of the pyramid structure 20, and can make the tops of multiple pyramid structures 20 tend to be consistent and smooth, thereby improving the light trapping effect on the surface of the battery cell.

[0035] In some embodiments, the height of the pyramid structure is greater than the second thickness. A larger height of the pyramid structure means a deeper light-trapping structure, which can more effectively capture and utilize incident light, reduce light reflection and scattering losses, and in addition, the passivation layer helps reduce surface recombination, and when its thickness is relatively small relative to the height of the pyramid, it will not significantly affect the light-trapping effect of the pyramid. When the height of the pyramid structure is greater than the thickness of the passivation layer, the passivation layer can more effectively cover the top and sides of the pyramid, forming a more uniform passivation effect, thereby reducing the number of surface recombination centers.

[0036] In this embodiment, preferably, the height of the pyramid structure 20 is less than 1.5 microns. No specific limitation is made here. The pyramid velvet structure formed by the height of the pyramid structure 20 within this range can generate a passivation layer with good film quality, so that the surface of the battery cell is better passivated and the possibility of leakage current is reduced.

[0037] like Figure 2 and Figure 3 As shown, in some embodiments, the pyramid structure 20 is in a prism shape or a pyramid shape (indicated by lines in the figure), and different etching methods form pyramid structures 20 with different structures, which are not limited by the present application. Specifically, when the pyramid structure 20 is in a prism shape, the top of the pyramid is a planar structure, and when the pyramid is in a pyramid shape, the top of the pyramid is a pointed structure.

[0038] like Figure 4 As shown, in some embodiments, the angle between the inclined surface of the pyramid structure 20 and the bottom of the pyramid structure 20 is 20° to 70°. In the present application, the angle between the inclined surface of the pyramid structure 20 and the bottom of the pyramid structure 20 is the angle between the side of the prism and the lower bottom of the prism, and the angle between the inclined surface of the pyramid structure 20 and the bottom of the pyramid structure 20 is the angle between the side of the pyramid and the bottom of the pyramid. Specifically, under this preferred angle between the inclined surface and the bottom, on the one hand, the surface of the battery cell has a lower reflectivity, and the light conversion efficiency of the solar cell is further improved. On the other hand, the transition between the multiple pyramid structures 20 can be smooth, and a good passivation layer can be formed. Preferably, the passivation layer between the bottoms of adjacent pyramid structures 20 is a smooth structure, so that a relatively smooth pyramid velvet structure is formed on the surface of the battery cell, which is convenient for the subsequent generation of an anti-reflection film layer with good film quality on the surface of the battery cell.

[0039] Furthermore, the passivation layer 30 may include at least one or a combination of 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 in sequence, which is not specifically limited here.

[0040] In the embodiment of the present application, the passivation layer has a first protruding structure 40 on the inclined surface of the pyramid structure, and / or the passivation layer has a second protruding structure 50 on the top of the pyramid structure, the first protruding structure 40 is randomly distributed on the passivation layer 30, and optionally, the second protruding structure 50 is also randomly distributed on the passivation layer 30. In this way, the specific surface area of ​​the passivation layer 30 can be increased, the light trapping effect on the surface of the solar cell can be improved, and the power generation efficiency of the solar cell can be improved.

[0041] Furthermore, the projection area of ​​the second protruding structure 50 along the thickness direction is greater than the projection area of ​​the first protruding structure 40 along the thickness direction. This further increases the specific surface area of ​​the top of the pyramid structure, thereby enhancing the light trapping effect on the surface of the cell. Preferably, the first protruding structure 40 and the second protruding structure 50 are arc-shaped protruding structures. Compared with the planar structure, the arc-shaped protruding structure can better match the angle of the incident light, reduce the direct reflection of the light on the interface, improve the utilization rate of the light, and guide the light to be reflected and scattered multiple times inside the material through its geometric characteristics, thereby extending the optical path and improving the light absorption efficiency. In addition, in the existing pyramid structure 20, there are fine cracks on the inclined surface of the pyramid structure 20, and the cracks are essentially recessed in the inclined surface of the pyramid structure 20. The recessed cracks are easy to hide debris and are not convenient for subsequent cleaning of the solar cell. In the present application, the passivation layer 30 on the inclined surface of the pyramid structure 20 has a first protruding structure 40 and the passivation layer at the top of the pyramid has a second protruding structure 50, that is, the first protruding structure 40 is protruding from the surface of the passivation layer 30 on the inclined surface, and the second protruding structure 50 is protruding from the surface of the passivation layer 30 at the top of the pyramid structure. While ensuring the pyramid velvet structure with low reflectivity, it is also beneficial to the subsequent cleaning of the solar cell.

[0042] It should be noted that when the top of the pyramid structure 20 is smoothed or modified into an arc shape in a subsequent process, the top of the pyramid structure 20 is determined by the extension line of the corresponding edge of the pyramid structure 20, and the inclined surface of the pyramid structure 20 can be determined.

[0043] 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 apex and the base of the pyramid; when the pyramid structure 20 is a prism with a protrusion, the inclined surface of the pyramid structure 20 is the surface formed by the upper base and the corresponding lower base of the prism with a protrusion.

[0044] A battery assembly includes the above-mentioned solar cell. Based on the above-mentioned solar cell, those skilled in the art know that a corresponding battery assembly can be obtained by using a plurality of the solar cells and / or other corresponding existing accessories.

[0045] In this embodiment, a plurality of solar cells in the battery assembly can be connected in series in sequence to form a battery string, thereby realizing the series bus output of the current. For example, the series connection of the battery cells can be realized by providing welding strips (bus bars, interconnecting strips), conductive backplanes, etc. It can be understood that in such an embodiment, the battery assembly may also include a metal frame, a backplane, photovoltaic glass, and an adhesive film. The adhesive film can be filled between the front and back of the back contact battery and the photovoltaic glass, adjacent battery cells, etc. As a filler, it can be a transparent colloid with good light transmittance and aging resistance. For example, the adhesive film can be an EVA adhesive film or a POE adhesive film. The specific selection can be made according to the actual situation and is not limited here.

[0046] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0047] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present 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, 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, and the second thickness is greater than the first thickness.

2. The solar cell according to claim 1, wherein: 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 according to claim 1, wherein: The tower height of the pyramid structure is greater than the second thickness.

4. The solar cell according to claim 1, wherein: The passivation layer has a first protruding structure on the inclined surface of the pyramid structure, and / or the passivation layer has a second protruding structure on the top of the pyramid structure.

5. The solar cell according to claim 4, characterized in that The first protrusion structures are randomly distributed on the passivation layer.

6. The solar cell according to claim 4, characterized in that A projection area of ​​the second protrusion structure along the thickness direction is greater than a projection area of ​​the first protrusion structure along the thickness direction.

7. The solar cell according to claim 4, characterized in that The first protruding structure and the second protruding structure are arc-shaped protruding structures.

8. The solar cell according to claim 1, wherein: The pyramid structure is in the shape of a prism or a pyramid.

9. The solar cell according to claim 1, wherein: The angle between the inclined surface of the pyramid structure and the bottom of the pyramid structure is 20° to 70°.

10. The solar cell according to claim 1, wherein: The inclined surface of the pyramid structure is a surface formed between the top of the pyramid structure and the bottom edge of the bottom of the pyramid structure.

11. The solar cell according to claim 1, wherein: The passivation layer between the bottoms of adjacent pyramid structures is a smooth structure.

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

13. A battery assembly, characterized in that: A solar cell comprising any one of claims 1 to 12.

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