Solar cell, manufacturing method thereof and photovoltaic module

Abstract

The invention discloses a solar cell and a manufacturing method thereof, and a photovoltaic module, relates to the technical field of photovoltaic, and aims to increase the contact area between an electrode structure and an interconnection piece, increase the interconnection adhesive force, further improve the connection strength between the interconnection piece and the electrode structure, and facilitate the improvement of the structural stability of the photovoltaic module comprising the solar cell. The solar cell comprises a cell substrate and an electrode structure formed on the cell substrate. Wherein the surface on which the electrode structure is formed on the battery substrate is a first surface, and the surface of one side, deviating from the battery substrate, of the electrode structure is a second surface. The first surface and the second surface are suede surfaces, the height of each position of the second surface is increased along with the increase of the height of the corresponding position of the first surface, and the height of each position of the second surface is reduced along with the reduction of the height of the corresponding position of the first surface. The solar cell is applied to a photovoltaic module. The manufacturing method of the solar cell is used for manufacturing the solar cell.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a solar cell and a manufacturing method thereof, and a photovoltaic module. Background Art

[0002] Photovoltaic solar cells are devices that directly convert light energy into electrical energy through the photoelectric effect. In the actual process of manufacturing solar cells, the semiconductor substrate used to manufacture solar cells is textured to form a velvet surface with light-trapping effect on the surface of the semiconductor substrate, thereby reducing the reflection of light by the solar cell, allowing more light to be refracted into the solar cell, which is beneficial to improving the utilization rate of light energy by the solar cell.

[0003] However, in the case where the existing solar cell includes an electrode structure formed on the velvet surface, the connection strength between the interconnection member such as the welding ribbon and the electrode structure is low, resulting in poor structural stability of the photovoltaic module including the solar cell. Summary of the invention

[0004] The object of the present invention is to provide a solar cell and a method for manufacturing the same, and a photovoltaic module, which are used to increase the contact area between the electrode structure included in the solar cell and the interconnection part, increase the interconnection adhesion, and further improve the connection strength between the interconnection part and the electrode structure, which is beneficial to improving the structural stability of the photovoltaic module including the solar cell.

[0005] In order to achieve the above-mentioned object, in the first aspect, the present invention provides a solar cell, which comprises: a cell substrate, and an electrode structure formed on the cell substrate. The surface on which the electrode structure is formed on the cell substrate is the first surface, and the surface on the side of the electrode structure facing away from the cell substrate is the second surface. Both the first surface and the second surface are velvet surfaces. The height of each position of the second surface increases as the height of the corresponding position of the first surface increases, and the height of each position of the second surface decreases as the height of the corresponding position of the first surface decreases.

[0006] In the case of adopting the above technical solution, the surface on which the electrode structure is formed on the battery substrate in the solar cell is the first surface, and the first surface is a velvet surface. Based on this, compared with a plane, the velvet surface has a good light trapping effect. Therefore, when the first surface is a velvet surface, more light can be refracted into the interior of the solar cell through the side of the battery substrate on which the electrode structure is formed, which is beneficial to improve the utilization rate of light by the solar cell. In addition, when the size of the battery substrate is the same, compared with the first surface being a plane, when the first surface is a velvet surface, the surface area of ​​the first surface is larger, which can increase the contact area between the electrode structure and the battery substrate, which is beneficial to reduce the contact resistance between the electrode structure and the battery substrate, and is beneficial to improve the electrical performance of the solar cell. At the same time, it can also increase the bonding tension between the electrode structure and the battery substrate, reduce the risk of the electrode structure detaching from the battery substrate when the interconnection circuit is connected, and improve the structural reliability of the solar cell.

[0007] Secondly, in the actual application process, it is necessary to connect multiple solar cells in series through interconnectors such as welding strips to form a solar cell string so that the output voltage of the photovoltaic module meets the actual working requirements. And it can be understood that the interconnector is usually in contact with the surface of the electrode structure on the side away from the battery substrate. In this case, the electrode structure formed on the first surface above, the surface of the side away from the battery substrate (i.e., the second surface) is also velvet. At this time, from a microscopic point of view, the velvet is a surface with an uneven micro-velvet structure, so compared with the second surface of the electrode structure being a plane, the surface roughness of the second surface of the electrode structure in the present invention is greater, so that its surface area is larger, thereby increasing the contact area between the electrode structure and the interconnector, increasing the connection adhesion between the interconnector and the electrode structure, and improving the connection strength of the two, and finally improving the structural stability of the photovoltaic module including the solar cell. From a macroscopic point of view, the velvet is an overall flat and long-range consistent surface, that is, the second surface is a macroscopically flat surface, which is conducive to making the connection tension between the various parts of the electrode structure and the interconnector uniform. At the same time, when the contact surface between the interconnection member and the electrode structure is a relatively flat surface, it is also advantageous for at least most areas of the interconnection member to be in contact with the electrode structure, so that there is good contact between the two.

[0008] Furthermore, the height of each position of the second surface increases as the height of the corresponding position of the first surface increases, and the height of each position of the second surface decreases as the height of the corresponding position of the first surface decreases. Based on this, in the actual manufacturing process, while manufacturing the first surface with a light trapping function, an electrode structure with corresponding undulating characteristics can be manufactured based on the first surface with a velvet surface. In order to obtain an electrode structure with a velvet surface on the second surface, it is not necessary to perform additional velveting treatment on the conductive material for manufacturing the electrode structure after depositing it, thereby reducing the manufacturing difficulty of the electrode structure with a velvet surface on the second surface and simplifying the manufacturing process of the electrode structure.

[0009] As a possible implementation scheme, when the thickness of the electrode structure is greater than or equal to 0.5 μm and less than or equal to 15 μm, the height variation amplitude of each position of the second surface and the corresponding position of the first surface is substantially the same. In this case, the second surface of the electrode structure has substantially the same surface undulation characteristics as the first surface of the battery substrate, thereby ensuring that the second surface of the electrode structure has a larger specific surface area, so that the connection adhesion between the interconnector and the electrode structure is increased while ensuring that the second surface of the electrode structure is a macroscopically flat surface, which is conducive to making the connection tension between each part of the electrode structure and the interconnector uniform. In other words, while being able to make the electrode structure and the interconnector have a larger connection adhesion, the two also have a higher connection tension uniformity.

[0010] As a possible implementation, when the thickness of the electrode structure is greater than or equal to 0.5 μm and less than or equal to 15 μm, the thickness of the electrode structure at various positions is the same. The beneficial effect in this case can be analyzed with reference to the beneficial effect of the above-mentioned case where the thickness of the electrode structure is greater than or equal to 0.5 μm and less than or equal to 15 μm, that the height variation amplitudes of various positions on the second surface and the corresponding positions on the first surface are substantially the same.

[0011] As a possible implementation method, when the thickness of the electrode structure is greater than 15 μm and less than or equal to 50 μm, the thickness of the electrode structure at the recessed position is greater than the thickness of the electrode structure at the raised position. In this case, the thickness of the electrode structure is relatively large, and the width of the electrode structure can be appropriately reduced while ensuring that the resistivity of the electrode structure remains unchanged, thereby ensuring that the electrode structure has good conductivity and current collection capabilities, while being conducive to reducing the shading area of ​​the electrode structure when the resistance of the electrode structure is constant, thereby improving the photoelectric conversion efficiency of the solar cell.

[0012] As a possible implementation solution, the suede surface is a pyramid-shaped suede surface.

[0013] When the above technical solution is adopted, since the pyramid-shaped velvet surface has a pentahedral velvet structure, compared with a velvet structure with a small number of surfaces such as V-shaped grooves, the pyramid-shaped velvet structure is conducive to increasing the specific surface area of ​​the velvet surface, thereby reducing the reflectivity of the first surface; at the same time, it can also increase the contact area between the electrode structure and the first surface, and reduce the contact resistance. In addition, when the second surface is a pyramid-shaped velvet surface, the connection tension between the electrode structure and the interconnection member can be increased, and the connection strength between the electrode structure and the interconnection member can be further improved.

[0014] As a possible implementation scheme, the average base size of the pyramid-shaped protrusion structure on both the first surface and the second surface is greater than or equal to 0.5 μm and less than or equal to 10 μm.

[0015] In the case of adopting the above technical solution, the average tower base size of the pyramid-shaped convex structure on the first surface and the second surface is within the above range, which can prevent the surface area of ​​the first surface and the second surface from being small due to the small average tower base size of the pyramid-shaped convex structure, and ensure that the first surface has a good light trapping effect while ensuring that the electrode structure has a large contact area with the battery substrate, preventing the electrode structure from being separated from the battery substrate in the interconnection access circuit or during the manufacturing process, and improving the stability of the electrode structure. In addition, it can also ensure that there is a large contact area between the second surface of the electrode structure and the interconnector, ensuring that there is a strong connection strength between the two. In addition, it can also prevent the macroscopic flatness of the second surface from being reduced due to the large average tower base size of the pyramid-shaped convex structure, and ensure that most areas of the electrode structure can contact with the interconnector with a flat contact surface. At the same time, the larger the size of the pyramid-shaped convex structure, the larger the surface area of ​​the velvet, and when the lateral width and length of the electrode structure are the same, the larger the size of the pyramid-shaped convex structure may cause the shading area of ​​the electrode structure to be larger. Based on this, when the average base size of the pyramid-shaped protrusion structure is within the above range, the size of the pyramid protrusion structure is appropriate, which is also beneficial to reduce the shading area of ​​the electrode structure, ensuring that more light can be refracted into the battery base through the first side.

[0016] As a possible implementation, the roughness within every 10 μm of the second surface is greater than or equal to 170 nm and less than or equal to 900 nm; the roughness within every 100 μm of the second surface is greater than or equal to 200 nm and less than or equal to 900 nm.

[0017] In the case of adopting the above technical solution, when other factors are the same, the roughness of the surface is proportional to the surface area of ​​the surface. Based on this, from a microscopic perspective, the roughness within every 10μm range and the roughness within every 100μm range of the second surface of the electrode structure are within the above range, which can prevent the surface area of ​​the second surface from being small due to the above roughness, ensure that there is a high connection adhesion between the electrode structure and the interconnection, and further reduce the risk of the interconnection being detached from the electrode structure when the interconnection is connected to the circuit. At the same time, it can also prevent the partial area of ​​the interconnection with a relatively flat contact surface from being difficult to fully contact with the corresponding area of ​​the second surface of the electrode structure due to the high degree of unevenness of the second surface due to the above roughness, increase the actual contact area between the two, and ensure that there is good interface electrical contact between the two.

[0018] As a possible implementation scheme, the second surface is composed of granular conductive protrusions, and there is no gap between adjacent conductive protrusions.

[0019] When the above technical solution is adopted, the granular conductive protrusions are conductive structures that protrude outward relative to the main surface of the second surface. Therefore, when the second surface is composed of granular conductive protrusions and there is no gap between adjacent conductive protrusions, the second surface can have a larger surface area, further increasing the connection adhesion between the electrode structure and the interconnection, and reducing the risk of the interconnection being detached from the electrode structure when the interconnection is connected to the circuit.

[0020] As a possible implementation solution, the size of the conductive protrusion is greater than or equal to 100 nm and less than or equal to 2000 nm.

[0021] In the case of adopting the above technical solution, the size of the conductive protrusion is within the above range, which can prevent the surface area of ​​the second surface from increasing insignificantly due to the small size of the conductive protrusion, ensure that the electrode structure and the interconnection have a high connection adhesion, and further improve the connection strength between the electrode structure and the interconnection. At the same time, it can also prevent the conductive protrusion from being too large, which will cause the macroscopic surface flatness of the second surface to be affected by the conductive protrusion and reduce, ensure that the connection tension between each part of the electrode structure and the interconnection is high and uniform, and ensure that the interconnection and the electrode structure have good contact.

[0022] As a possible implementation scheme, the electrode structure includes a plurality of electrodes, each electrode having a main body and continuous transition portions located on both sides of the main body along the width direction. The average height of the main body is greater than the average height of the continuous transition portions.

[0023] In the case of adopting the above technical solution, compared with the existing electrode structure manufactured by screen printing process, which has a plurality of discretely distributed conductive residues formed by part of the conductive paste entering the gap between the screen printing screen and the battery substrate due to the poor sealing between the screen printing screen and the battery substrate, the two sides of each electrode in the present invention along the width direction are continuous transition parts, and the continuous transition part is a transition part without interruption, and the continuous transition part is continuous and uninterrupted along the width direction and the length direction of the electrode. Based on this, the carriers generated after the battery substrate absorbs photons collected in the continuous transition part can be conducted to the main body connected to itself, and the collected carriers will not be unable to be extracted due to its own discreteness, thereby improving the carrier collection capacity of the electrode structure.

[0024] As a possible implementation scheme, the boundary of the continuous transition portion away from the main body is roughly parallel to the boundary of the main body. In this case, along the length extension direction of each electrode, the width of each part of the continuous transition portion is roughly the same, so that the degree of improvement of the adhesion of each part of the electrode along the length direction on the surface of the electrode base of the continuous transition portion is roughly the same, ensuring the structural stability of each part of the electrode along the length direction; at the same time, it can also make the degree of improvement of the conductivity of each part of the electrode in the continuous transition part roughly the same, so that each part of the electrode has roughly the same carrier collection ability, which is conducive to making each part of the battery base of the solar cell have a balanced number of carriers in the working state, reducing the probability of recombination due to uneven carrier distribution, and thus helping to improve the photoelectric conversion efficiency of the solar cell.

[0025] As a possible implementation scheme, the angle between the surface of the continuous transition portion away from the main body and the horizontal plane is greater than or equal to 45° and less than 90°.

[0026] When the above technical solution is adopted, the angle between the surface of the continuous transition portion away from the main body and the horizontal plane is within the above range, which can prevent the steepness of the transition of the two sides of the electrode along the width direction relative to the second surface due to the large angle, thereby ensuring that the electrode has a high mechanical strength. In addition, it can also prevent the continuous transition portion from extending too wide along the width direction of the main body due to the small angle, thereby reducing the shading area of ​​the continuous transition portion on the first surface, which is conducive to allowing more light to be refracted into the battery base through the first surface, further improving the photoelectric conversion efficiency of the solar cell.

[0027] As a possible implementation scheme, the width of the above-mentioned continuous transition portion is greater than or equal to 1 μm and less than or equal to 15 μm. The beneficial effects in this case can be analyzed with reference to the beneficial effects of the angle between the surface of the continuous transition portion away from the main body and the horizontal plane being greater than or equal to 45° and less than 90° as mentioned above, which will not be repeated here.

[0028] As a possible implementation scheme, the height of each position of the continuous transition portion gradually decreases along the width direction of the main body and away from the main body. In this case, the continuous transition portion has a higher structural stability, further improving the adhesion of each electrode on the surface of the battery substrate and improving the structural reliability of the solar cell.

[0029] As a possible implementation scheme, the thickness of the main body is greater than or equal to 500nm and less than or equal to 30μm. In this case, the thickness of the main body included in each electrode is within the above range, which can prevent the transmission resistance of the electrode from being high due to the small thickness of the main body included in the electrode, and ensure that the electrode structure has good conductivity. At the same time, it can also prevent the large amount of consumables used in the electrode structure and the long process cycle due to the large thickness of the main body included in the electrode, which is conducive to controlling the manufacturing cost of solar cells and improving the process efficiency of solar cells.

[0030] As a possible implementation scheme, the width of the main body is greater than or equal to 10 μm and less than or equal to 500 μm. In this case, the width of the main body included in each electrode is within the above range, which can prevent the electrode from easily collapsing during manufacturing or interconnection due to the large thickness-to-width ratio of the electrode without increasing the resistance due to the small width of the main body, thereby improving the structural stability of the electrode. At the same time, it can also prevent the large shading area of ​​the electrode due to the large width, ensuring that the solar cell has a high photoelectric conversion efficiency.

[0031] As a possible implementation scheme, the electrode structure includes a collector electrode and a bus electrode that are integrally formed and cross-arranged.

[0032] In the case of adopting the above technical solution, the collector electrode is used to collect the carriers generated by the battery substrate after absorbing photons, and conduct them to the bus electrode, and then lead out by the bus electrode. In addition, because the temperature when manufacturing the electrode structure is high, and the manufacturing environment of the electrode structure in the prior art is mostly non-vacuum state, an insulating layer of materials including metal oxides and the like is often formed on the surface of the formed electrode structure. Based on this, in the prior art, when the collector electrode and the bus electrode are manufactured step by step, there will be a certain interface resistance between the collector electrode and the bus electrode due to the existence of the insulating layer, which affects the conduction of carriers. In the present invention, the cross-arranged collector electrode and the bus electrode included in the electrode structure are integrally formed. At this time, the collector electrode and the bus electrode are formed at the same time in the actual manufacturing process, which simplifies the manufacturing process of the electrode structure, so that there will be no insulating layer byproducts generated by step-by-step manufacturing between the collector electrode and the bus electrode, and the interface resistance between the collector electrode and the bus electrode is eliminated, which is beneficial to the conduction of carriers between the two, and then it is beneficial to improve the electrical performance of solar cells.

[0033] As a possible implementation scheme, the electrode structure is a solid structure without pores. In this case, each part of the electrode structure can effectively conduct carriers, which is conducive to improving the conductivity of each part of the electrode structure. At the same time, the mechanical strength of the electrode structure can also be improved, reducing the risk of problems such as breakage or bending during the interconnection process between the electrode structure and the interconnection part or during actual use.

[0034] As a possible implementation scheme, the absolute value of the difference between the roughness of the first surface and the roughness of the second surface is greater than or equal to 0.5 μm and less than or equal to 5 μm. At this time, the absolute value of the difference between the roughness of the first surface and the roughness of the second surface is small, that is, the difference in surface morphology between the two is small. In other words, the second surface of the electrode structure has an undulating feature that is basically consistent with the first surface, which is conducive to the second surface of the electrode structure also having a high macroscopic surface flatness, and can further improve the uniformity of the connection tension between the various parts of the electrode structure and the interconnection. At the same time, it is conducive to the second surface of the electrode structure also having a certain microscopic surface roughness, ensuring that the electrode structure and the interconnection have a high connection strength, reducing the risk of the interconnection being detached from the electrode structure when the interconnection is connected to the circuit, and improving the structural reliability of the photovoltaic module including the solar cell.

[0035] In a second aspect, the present invention further provides a photovoltaic module, which includes the solar cell provided by the first aspect and various implementations thereof.

[0036] The beneficial effects of the second aspect of the present invention can be analyzed by referring to the beneficial effects of the first aspect and its various implementations, and will not be repeated here.

[0037] In a third aspect, the present invention also provides a method for manufacturing a solar cell, the method comprising: first, forming a polymer mask provided with an electrode pattern. Next, transferring and fixing the polymer mask on a first surface of a battery substrate. Next, under the protection of the polymer mask, forming an electrode structure on the first surface by vacuum coating. The surface of the electrode structure facing away from the battery substrate is the second surface. Both the first surface and the second surface are velvet, and the height of each position of the second surface increases as the height of the corresponding position of the first surface increases, and the height of each position of the second surface decreases as the height of the corresponding position of the first surface decreases.

[0038] The beneficial effects of the third aspect of the present invention can be analyzed by referring to the beneficial effects of the first aspect and its various implementations, and will not be repeated here.

[0039] As a possible implementation scheme, the deposition rate of forming the electrode structure on the first surface by vacuum coating is greater than 0 and less than or equal to 1 nm / s.

[0040] When the above technical solution is adopted, in the actual manufacturing process, within a certain range, the deposition rate is proportional to the deposition defects. Therefore, when the deposition rate of the electrode structure on the first surface of the battery substrate is within the above range, the deposition rate of the electrode structure on the first surface is relatively small, which is beneficial to reducing the defects in the manufactured electrode structure and to making the second surface of the electrode structure maintain substantially the same morphological features as the first surface, thereby ensuring that the second surface of the manufactured electrode structure has substantially the same surface roughness as the first surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0042] Figure 1 A longitudinal cross-sectional schematic diagram of a partial structure of a solar cell in an embodiment of the present invention;

[0043] Figure 2 An enlarged schematic diagram of the structure of the second surface of the electrode structure with a thickness of 2 μm when the velvet surface is a pyramid-shaped velvet surface in an embodiment of the present invention;

[0044] Figure 3 It is a schematic diagram of the structure enlargement of the second surface of the electrode structure with a thickness of 5 μm when the velvet surface is a pyramid-shaped velvet surface in an embodiment of the present invention;

[0045] Figure 4 It is a schematic diagram of the structure enlargement of the second surface of the electrode structure with a thickness of 10 μm when the velvet surface is a pyramid-shaped velvet surface in an embodiment of the present invention;

[0046] Figure 5 It is an enlarged schematic longitudinal cross-sectional view of the structure at the junction of the collector electrode and the bus electrode in an embodiment of the present invention;

[0047] Figure 6 It is an enlarged schematic longitudinal cross-sectional view of the structure at the junction of the collector electrode and the bus electrode in the related art;

[0048] Figure 7 It is an enlarged schematic top view of the electrode structure in an embodiment of the present invention;

[0049] Figure 8 It is an enlarged schematic longitudinal cross-sectional view of an electrode structure in an embodiment of the present invention;

[0050] Fig. 9 It is an enlarged longitudinal cross-sectional schematic diagram of another structure of the electrode structure in an embodiment of the present invention;

[0051] Fig.10 It is a top view enlarged schematic diagram of an electrode structure in the related art;

[0052] Fig.11 It is an enlarged longitudinal cross-sectional schematic diagram of another structure of the electrode structure in the embodiment of the present invention;

[0053] Fig.12 It is an enlarged schematic diagram of a longitudinal cross-section of an electrode structure in the related art;

[0054] Fig.13 It is a schematic diagram of a structure of a solar cell having an electrode structure formed on one side when the velvet surface is a pyramid-shaped velvet surface in an embodiment of the present invention, which is magnified 1000 times;

[0055] Fig.14 is a schematic diagram of a structure at the second surface of the electrode structure magnified 5000 times when the velvet surface is a pyramid-shaped velvet surface in an embodiment of the present invention;

[0056] Fig.15 It is a schematic diagram of a structure of a solar cell formed with an electrode structure when the velvet surface is a pyramid-shaped velvet surface and is magnified 1000 times in the related art;

[0057] Fig.16 It is a schematic diagram of a structure at the second surface of an electrode structure magnified 5000 times when the structure is manufactured by screen printing process in the related art and the velvet surface is a pyramid-shaped velvet surface;

[0058] Fig.17 It is a schematic diagram of a structure of a solar cell formed with an electrode structure when the electroplating process is used in the related art and the velvet surface is a pyramid-shaped velvet surface, which is magnified 1000 times;

[0059] Fig.18 It is a schematic diagram of the structure at the second surface of the electrode structure magnified 5000 times when the electroplating process is adopted in the related art and the velvet surface is a pyramid-shaped velvet surface.

[0060] Figure numerals: 11 is a battery substrate, 12 is a first surface, 13 is an electrode structure, 14 is a second surface, 15 is a conductive protrusion, 16 is a collecting electrode, 17 is a bus electrode, 18 is a main body, 19 is a continuous transition portion, and 20 is a pore. DETAILED DESCRIPTION

[0061] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0062] Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may further design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0063] In the context of the present disclosure, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. In addition, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "under" the other layer / element. In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0064] 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. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0065] In the description of the present invention, 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 or an electrical connection; 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 the present invention can be understood according to specific circumstances.

[0066] Photovoltaic solar cells are devices that directly convert light energy into electrical energy through the photoelectric effect. How to improve the photoelectric conversion efficiency of the above solar cells has always been a top priority in solar cell design and optimization. Specifically, in the actual process of manufacturing solar cells, the semiconductor substrate of the solar cell to be manufactured is generally first subjected to a velvet treatment to form a velvet structure at least on the light-facing surface of the semiconductor substrate. The velvet structure on the light-facing surface can trap light to reduce the reflection of light by the solar cell, so that more light can be refracted into the solar cell, thereby improving the utilization rate of light energy by the solar cell.

[0067] However, in the actual manufacturing process, the roughness of the upper surface of the electrode structure formed on the uneven velvet surface by the existing electrode manufacturing method is relatively small. When the lateral width and length are fixed, the surface area of ​​the electrode structure with a smaller surface roughness is also smaller, so that when different solar cells are interconnected to form a photovoltaic module, the contact area between the interconnection parts such as the welding ribbon and the electrode structure for interconnection is small, resulting in a small interconnection adhesion between the two, and then in the subsequent lamination packaging and use process, there is a risk of falling off, resulting in poor structural stability of the photovoltaic module.

[0068] In order to solve the above technical problems, in the first aspect, an embodiment of the present invention provides a solar cell. In terms of the type of battery, the solar cell provided by the embodiment of the present invention can be any type of solar cell such as a PERC (Passivated Emitter and Rear Cell) battery, an HJT (Heterojunction Technology) battery, an SE (selective emitter) battery, a TOPcon (Tunnel Oxide Passivated Contact) battery, etc. In terms of the formation position of the positive and negative electrodes of the battery, the solar cell provided by the embodiment of the present invention can be a double-sided contact solar cell in which the positive and negative electrodes are located on different surfaces, or it can be a back contact battery in which the positive and negative electrodes are both located on the backlight side.

[0069] Specifically, the solar cell includes: Figures 1 to 4 As shown, a battery substrate 11 and an electrode structure 13 formed on the battery substrate 11. The surface of the battery substrate 11 on which the electrode structure 13 is formed is the first surface 12, and the surface of the electrode structure 13 on the side away from the battery substrate 11 is the second surface 14. The first surface 12 and the second surface 14 are both velvet. The height of each position of the second surface 14 increases as the height of the corresponding position of the first surface 12 increases, and the height of each position of the second surface 14 decreases as the height of the corresponding position of the first surface 12 decreases.

[0070] Specifically, in the embodiment of the present invention, Figure 1 As shown, the height of each position of the first surface 12 in the battery substrate 11 and the height of each position in the electrode structure 13 are obtained by taking the same horizontal plane as a reference standard. In addition, the corresponding position of the first surface corresponding to each position of the second surface mentioned above refers to: the position of the first surface directly below each position of the second surface along the vertical direction.

[0071] When the above technical solution is adopted, Figures 1 to 4 As shown, the surface on which the electrode structure 13 is formed on the battery substrate 11 of the solar cell is the first surface 12, and the first surface 12 is a velvet surface. Based on this, compared with a plane, the velvet surface has a good light trapping effect. Therefore, when the first surface 12 is a velvet surface, more light can be refracted into the interior of the solar cell through the side of the battery substrate 11 where the electrode structure 13 is formed, which is beneficial to improve the utilization rate of light by the solar cell. In addition, when the size of the battery substrate 11 is the same, compared with the first surface being a plane, when the first surface 12 is a velvet surface, the surface area of ​​the first surface 12 is larger, which can increase the contact area between the electrode structure 13 and the battery substrate 11, which is beneficial to reduce the contact resistance between the electrode structure 13 and the battery substrate 11, and is beneficial to improve the electrical performance of the solar cell. At the same time, the bonding tension between the electrode structure 13 and the battery substrate 11 can also be increased, reducing the risk of the electrode structure 13 being detached from the battery substrate 11 when the interconnection circuit is connected, and improving the structural reliability of the solar cell. Secondly, in the actual application process, multiple solar cells need to be connected in series through interconnectors such as welding strips to form a solar cell string so that the output voltage of the photovoltaic module meets the actual working requirements. It can be understood that the interconnector is usually in contact with the surface of the electrode structure 13 facing away from the battery substrate 11. In this case, the surface of the electrode structure 13 formed on the first surface 12 facing away from the battery substrate 11 (i.e., the second surface 14) is also a velvet surface. Figures 1 to 4As shown, the velvet surface is a surface with an uneven micro-velvet structure. Therefore, compared with the second surface of the electrode structure being a plane, the surface roughness of the second surface 14 of the electrode structure 13 in the embodiment of the present invention is greater, so that its surface area is larger, thereby increasing the contact area between the electrode structure 13 and the interconnection part, increasing the connection adhesion between the interconnection part and the electrode structure 13, and improving the connection strength between the two, and finally improving the structural stability of the photovoltaic module including the solar cell. From a macroscopic perspective, the velvet surface is an overall flat and long-range consistent surface, that is, the second surface 14 is a macroscopically flat surface, which is conducive to making the connection tension between each part of the electrode structure 13 and the interconnection part uniform. At the same time, when the contact surface between the interconnection part and the electrode structure 13 is a relatively flat surface, it is also conducive to making at least most areas of the interconnection part contact with the electrode structure 13, so that there is good contact between the two. Furthermore, the height of each position of the second surface 14 increases as the height of the corresponding position of the first surface 12 increases, and the height of each position of the second surface 14 decreases as the height of the corresponding position of the first surface 12 decreases, that is, the second surface 14 rises and falls along with the rise and fall of the first surface 12. Based on this, in the actual manufacturing process, while manufacturing the first surface 12 with a light trapping function, an electrode structure 13 with corresponding undulating characteristics can be manufactured based on the first surface 12 with a velvet surface. In order to obtain the electrode structure 13 with a velvet surface on the second surface 14, it is not necessary to perform additional velveting treatment on the conductive material for manufacturing the electrode structure 13 after depositing it, thereby reducing the manufacturing difficulty of the electrode structure 13 with a velvet surface on the second surface 14 and simplifying the manufacturing process of the electrode structure 13.

[0072] In actual application, the specific structure of the above-mentioned battery substrate can be determined according to the type of solar cell, and is not specifically limited here. For example, in the case where the solar cell is a heterojunction cell, the battery substrate can at least include a silicon substrate, and an intrinsic amorphous silicon layer and an impurity-doped amorphous silicon layer stacked in sequence on one side of the silicon substrate along the thickness direction of the silicon substrate. The conductivity type of the impurities in the impurity-doped amorphous silicon layer is opposite to the conductivity type of the silicon substrate.

[0073] In addition, at least one of the light-facing surface and the backlight surface of the battery substrate is a velvet surface. Specifically, only the light-facing side of the battery substrate may be a velvet surface, or only the backlight side of the battery substrate may be a velvet surface, or both the light-facing side and the backlight side of the battery substrate may be velvet surfaces. Specifically, the surface morphology of the light-facing side and the backlight side of the battery substrate may be determined according to the actual application scenario, and is not specifically limited here.

[0074] In the above case, the surface on which the electrode structure is formed on the battery substrate is the first surface, and the first surface is the light-facing surface and / or the backlight surface of the battery substrate that is a velvet surface.

[0075] For example, when the light-facing surface of the battery substrate is a velvet surface and the backlight surface is a plane, the first surface of the battery substrate is the light-facing surface, and the electrode structure is formed on the light-facing side of the battery substrate.

[0076] For another example, when the light-facing surface of the battery substrate is a flat surface and the backlight surface is a velvet surface, the first surface of the battery substrate is the backlight surface, and the electrode structure is formed on the backlight side of the battery substrate.

[0077] For another example: when both the light-facing surface and the backlight surface of the cell substrate are velvet surfaces, the first surface of the cell substrate is at least one of the light-facing surface and the backlight surface. In this case, it can be determined according to the type of solar cell. When the solar cell is a double-sided contact solar cell, the first surface of the cell substrate is at least one of the light-facing surface and the backlight surface. When the solar cell is a back-contact cell, the first surface of the cell substrate is the backlight surface of the cell substrate.

[0078] As for the type and size of the velvet structure on the first surface, since the electrode structure is formed on the first surface of the battery substrate, and the height of each position of the second surface increases with the increase of the height of the corresponding position of the first surface, and the height of each position of the second surface decreases with the decrease of the height of the corresponding position of the first surface, the type and size of the velvet structure on the first surface will not only affect its own light trapping characteristics and the bonding strength between the electrode structure and itself, but also affect the morphology of the second surface of the electrode structure formed on the battery substrate. Therefore, the type and size of the velvet structure on the first surface can be set according to the requirements of the light trapping characteristics of the first surface, the bonding strength between the battery substrate and the electrode structure, and the morphology of the second surface in the actual application scenario, as long as it can be applied to the solar cell provided in the embodiment of the present invention.

[0079] For example, the suede structure of the first surface may be a pyramid-shaped convex structure, a V-shaped groove concave structure, an inverted pyramid-shaped concave structure, a nano-hole structure, a goose eye structure or a lotus leaf structure.

[0080] It is worth noting that when the velvet structure is a pyramid-shaped protruding structure, the above-mentioned first surface is a pyramid-shaped velvet. Based on this, since the height of each position of the second surface increases with the increase of the height of the corresponding position of the first surface, and the height of each position of the second surface decreases with the decrease of the height of the corresponding position of the first surface, the second surface is also a pyramid-shaped velvet. In this case, since the velvet structure of the pyramid-shaped velvet is a pentahedral structure, compared with the velvet structure with a smaller number of surfaces such as V-shaped grooves, the pyramid-shaped velvet structure is conducive to increasing the specific surface area of ​​the velvet, and then helping to reduce the reflectivity of the first surface; at the same time, it can also increase the contact area between the electrode structure and the first surface, and reduce the contact resistance. In addition, when the second surface is a pyramid-shaped velvet, the connection tension between the electrode structure and the interconnection can be increased, and the connection strength between the electrode structure and the interconnection can be further improved.

[0081] In addition, the specific size of the velvet structure can be determined according to the type of velvet structure and the requirements for the light trapping characteristics of the velvet in the actual application scenario. Exemplarily, the average base size of the pyramid-shaped raised structure on the first and second surfaces is greater than or equal to 0.5 μm and less than or equal to 10 μm. For example: the average base size of the pyramid-shaped raised structure on the first and second surfaces can be 0.5 μm, 1 μm, 3 μm, 6 μm, 9 μm or 10 μm, etc. In this case, the average base size of the pyramid-shaped raised structure on the first and second surfaces is within the above range, which can prevent the surface area of ​​the first and second surfaces from being smaller due to the smaller average base size of the pyramid-shaped raised structure. While ensuring that the first surface has a good light trapping effect, it ensures that the electrode structure has a larger contact area with the battery substrate, prevents the electrode structure from being separated from the battery substrate in the interconnection circuit or during the manufacturing process, and improves the stability of the electrode structure. In addition, it can also ensure that there is a larger contact area between the second surface of the electrode structure and the interconnector, ensuring that there is a stronger connection strength between the two. In addition, it is also possible to prevent the macroscopic flatness of the second surface from being reduced due to the large average tower base size of the pyramid-shaped protrusion structure, ensuring that most areas of the electrode structure can contact the interconnection member with a flat contact surface. At the same time, the larger the size of the pyramid-shaped protrusion structure, the larger the surface area of ​​the velvet surface. Therefore, when the lateral width and length of the electrode structure are the same, the larger the size of the pyramid-shaped protrusion structure, the larger the shading area of ​​the electrode structure. Based on this, the average tower base size of the pyramid-shaped protrusion structure is within the above range, and it is also possible to prevent the shading area of ​​the electrode structure from being affected by the large average tower base size of the pyramid-shaped protrusion structure, ensuring that more light can be refracted into the battery substrate through one side of the first surface.

[0082] For the above electrode structure, from the aspect of morphology, the height of each position of the second surface in the electrode structure increases as the height of the corresponding position of the first surface in the battery substrate increases, and the height of each position of the second surface in the electrode structure decreases as the height of the corresponding position of the first surface in the battery substrate decreases. In other words, the second surface in the electrode structure rises and falls with the rise and fall of the first surface in the battery substrate. In addition, Figures 1 to 4 As shown, the relationship between the height variation amplitude at each position of the second surface 14 of the electrode structure 13 and the height variation amplitude at the corresponding position of the first surface 12 of the battery substrate 11 is related to the thickness of the electrode structure 13. Within a certain range, the smaller the thickness of the electrode structure 13, the closer the height variation amplitude at each position of the second surface 14 of the electrode structure 13 and the height variation amplitude at the corresponding position of the first surface 12 of the battery substrate 11 are; accordingly, the roughness of the two velvet surfaces are roughly the same. When the thickness of the electrode structure 13 is larger, there is a certain difference between the height variation amplitude at each position of the second surface 14 of the electrode structure 13 and the height variation amplitude at the corresponding position of the first surface 12 of the battery substrate 11; accordingly, the roughness of the two velvet surfaces is also different, but the difference is small. Among them, Figures 2 to 4 They are respectively schematic diagrams of the second surface structures of a 2 μm thick electrode structure, a 5 μm thick electrode structure, and a 10 μm thick electrode structure when the velvet surface is a pyramid-shaped velvet surface in an embodiment of the present invention. Figures 2 to 4 It can be seen that when the surface morphology of the first surface of the battery substrate is the same, the surface morphology of the second surface of the electrode structures with different thicknesses is different.

[0083] Exemplarily, when the thickness of the electrode structure is greater than or equal to 0.5 μm and less than or equal to 15 μm, the thickness of the electrode structure is the same at various positions. For example: when the thickness of the electrode structure is 0.5 μm, 1 μm, 5 μm, 10 μm or 15 μm, the thickness of the electrode structure is the same at various positions. In this case, the second surface of the electrode structure has substantially the same surface undulation characteristics as the first surface of the battery substrate, thereby ensuring that the second surface of the electrode structure has a larger specific surface area, so that the connection adhesion between the interconnection and the electrode structure is increased while ensuring that the second surface of the electrode structure is a macroscopically flat surface, which is conducive to making the connection tension between various parts of the electrode structure and the interconnection uniform. In other words, while being able to have a larger connection adhesion between the electrode structure and the interconnection, the two also have a higher connection tension uniformity.

[0084] Exemplarily, when the thickness of the electrode structure is greater than 15 μm and less than or equal to 50 μm, the thickness of the electrode structure at the recessed position is greater than the thickness of the electrode structure at the raised position. For example: when the thickness of the electrode structure is 16 μm, 20 μm, 30 μm, 40 μm or 50 μm, the thickness of the electrode structure at the recessed position is greater than the thickness of the electrode structure at the raised position. In this case, the thickness of the electrode structure is relatively large, and the width of the electrode structure can be appropriately reduced while ensuring that the resistivity of the electrode structure remains unchanged, thereby ensuring that the electrode structure has good conductivity and current collection capabilities, while helping to reduce the shading area of ​​the electrode structure and improve the photoelectric conversion efficiency of the solar cell.

[0085] Specifically, the morphological features such as the roughness difference between the first surface of the battery substrate and the second surface of the electrode structure, the roughness of the second surface, and the thickness of the electrode structure can be determined based on the requirements for the similarity of the undulations between the first surface of the battery substrate and the second surface of the electrode structure in the actual application scenario, as well as the morphology of the velvet surface, and are not specifically limited here.

[0086] Exemplarily, the absolute value of the difference between the roughness of the first surface and the roughness of the second surface can be greater than or equal to 0.5 μm and less than or equal to 5 μm. For example: the absolute value of the difference between the roughness of the first surface and the roughness of the second surface is 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, etc. In this case, the absolute value of the difference between the roughness of the first surface and the roughness of the second surface is small, that is, the difference in surface morphology between the two is small. In other words, the first surface is a conventional velvet surface of the battery substrate. Although the conventional velvet surface is microscopically convex, it is roughly flat from a macroscopic point of view, and the second surface of the electrode structure has an undulating feature that is substantially consistent with the first surface, which is conducive to making the second surface of the electrode structure also have a higher macroscopic surface flatness, which can further improve the uniformity of the connection tension between the various parts of the electrode structure and the interconnection. At the same time, it is conducive to making the second surface of the electrode structure also have a certain microscopic surface roughness, ensuring that the electrode structure and the interconnection have a higher connection strength, reducing the risk of the interconnection being detached from the electrode structure when the interconnection is connected to the circuit, and improving the structural reliability of the photovoltaic module including the solar cell.

[0087] Exemplarily, the roughness within every 10 μm range of the second surface may be greater than or equal to 170 nm and less than or equal to 900 nm, and the roughness within every 100 μm range of the second surface may be greater than or equal to 200 nm and less than or equal to 900 nm. For example: the roughness within every 10 μm range of the second surface may be 180 nm, 190 nm, 200 nm, 400 nm, 500 nm, 700 nm or 900 nm, etc., and the roughness within every 100 microns range of the second surface may be 200 nm, 400 nm, 500 nm, 700 nm or 900 nm, etc. In this case, when other factors are the same, the roughness of the surface is proportional to the surface area of ​​the surface. Based on this, from a microscopic perspective, the roughness of the second surface of the electrode structure is within the above range, which can prevent the surface area of ​​the second surface from being smaller due to the smaller roughness of the second surface of the electrode structure, ensure that the electrode structure and the interconnect have a higher connection adhesion, and further reduce the risk of the interconnect being detached from the electrode structure when the interconnect is connected to the circuit. At the same time, it can also prevent the second surface from being more uneven due to the greater roughness of the second surface, which would cause some areas of the interconnection member with a relatively flat contact surface to be difficult to fully contact with the corresponding areas of the second surface of the electrode structure, thereby increasing the actual contact area between the two and ensuring good interface electrical contact between the two.

[0088] Alternatively, the second side of the electrode structure may be a velvet surface having substantially the same surface characteristics as the first side of the battery substrate. Figures 2 to 4 As shown, the second surface 14 is composed of granular conductive protrusions 15, and there is no gap between adjacent conductive protrusions 15. In this case, the granular conductive protrusions 15 are conductive structures that protrude outward relative to the main surface of the second surface 14. Therefore, when the second surface 14 is composed of granular conductive protrusions 15 and there is no gap between adjacent conductive protrusions 15, the second surface 14 can have a larger surface area, further increasing the connection adhesion between the electrode structure and the interconnection part, and reducing the risk of the interconnection part being separated from the electrode structure when the interconnection is connected to the circuit.

[0089] Specifically, the granular conductive protrusions are protrusions formed on the main part of the electrode structure during the manufacturing process of the electrode structure; and the size of the conductive protrusions is proportional to the thickness of the electrode structure. Based on this, the distribution and size of the granular conductive protrusions on the second surface can be determined according to the manufacturing process and thickness of the electrode structure, as well as the actual application scenario, and are not specifically limited here.

[0090] Exemplarily, the size of the conductive protrusion may be greater than or equal to 100nm and less than or equal to 2000nm. For example, the size of the conductive protrusion may be 100nm, 400nm, 800nm, 1200nm, 1600nm or 2000nm, etc. In this case, the size of the conductive protrusion is within the above range, which can prevent the surface area of ​​the second surface from increasing significantly due to the small size of the conductive protrusion, ensure that the electrode structure and the interconnect have a high connection adhesion, and further improve the connection strength between the electrode structure and the interconnect. At the same time, it can also prevent the conductive protrusion from being too large, which causes the macroscopic surface flatness of the second surface to be affected by the conductive protrusion and reduced, ensure that the parts of the electrode structure and the interconnect have a high connection tension uniformity, and ensure that the interconnect and the electrode structure have good contact.

[0091] For example, Figures 2 to 4 As shown, the conductive protrusions 15 are randomly distributed on the second surface 14. In this case, the distribution positions of the conductive protrusions 15 on the second surface 14 are random, which can reduce the manufacturing accuracy of the electrode structure with the conductive protrusions 15.

[0092] From a structural perspective, the electrode structure may only include a plurality of collector electrodes extending along a first direction and spaced apart along a second direction. The first direction and the second direction may be any two different directions parallel to the main direction of the first surface. The collector electrode may be in a straight line, a wavy line, or an arc-shaped curve.

[0093] Or, if Figure 5 As shown, the electrode structure may also include a collector electrode 16 and a bus electrode 17 that are integrally formed and cross-arranged. The collector electrode 16 and the bus electrode 17 are integrally formed, which means that the collector electrode 16 and the bus electrode 17 are manufactured and formed at the same time, that is, the collector electrode 16 and the bus electrode 17 can be formed at the same time through a single manufacturing process. In this case, the collector electrode 16 is used to collect the carriers generated by the battery substrate 11 after absorbing photons, and conduct them to the bus electrode 17, and then the bus electrode 17 is led out. In addition, as Figure 6 As shown, because the temperature during the manufacture of the electrode structure is high, and the manufacturing environment of the electrode structure in the prior art is mostly non-vacuum, an insulating layer of materials including metal oxides is often formed on the surface of the formed electrode structure. Based on this, in the prior art, when the collector electrode 16 and the bus electrode 17 are manufactured step by step, there will be a certain interface resistance between the collector electrode 16 and the bus electrode 17 due to the existence of the insulating layer, which affects the conduction of carriers. Figure 5As shown, the cross-arranged collecting electrode 16 and bus electrode 17 included in the electrode structure in the embodiment of the present invention are integrally formed. In this case, the collecting electrode 16 and the bus electrode 17 are formed simultaneously during the actual manufacturing process, which simplifies the manufacturing process of the electrode structure. There is no insulating layer by-product generated by step-by-step manufacturing between the collecting electrode 16 and the bus electrode 17, and the interface resistance between the collecting electrode 16 and the bus electrode 17 is eliminated, which is beneficial to the carrier conduction between the two, and further helps to improve the electrical performance of the solar cell.

[0094] Specifically, the different collector electrodes included in the electrode structure can extend along the first direction and be arranged at intervals along the second direction. The different bus electrodes included in the electrode structure can extend along the second direction and be arranged at intervals along the first direction. Among them, the number of collector electrodes and bus electrodes included in the electrode structure, the spacing between two adjacent collector electrodes and the spacing between two adjacent bus electrodes, and the specific directions of the first direction and the second direction can be set according to the actual application scenario and are not specifically limited here.

[0095] In addition, in actual application, the electrode structure includes multiple electrodes. Specifically, when the electrode structure includes only a collector electrode, the multiple electrodes are multiple collector electrodes. When the electrode structure includes a collector electrode and a bus electrode, the multiple electrodes include multiple collector electrodes and multiple bus electrodes, and each electrode is a collector electrode or a bus electrode. In the above case, Figures 7 to 9 As shown in FIG. 1 , each electrode may also have a main body 18 and continuous transition portions 19 located on both sides of the main body 18 along the width direction. The average height of the main body 18 is greater than the average height of the continuous transition portions 19. In this case, Fig.10 As shown, compared with the existing electrode structure manufactured by screen printing process, due to the poor sealing between the screen printing screen and the battery substrate, there are some discrete conductive residues formed by part of the conductive paste entering the gap between the two, such as Figure 7 As shown, each electrode in the embodiment of the present invention has continuous transition portions 19 on both sides along the width direction, and the continuous transition portion 19 is a transition portion without interruption, and the continuous transition portion 19 is continuous and uninterrupted along the width direction and the length direction of the electrode. Based on this, the continuous transition portion 19 collects the carriers generated after the battery substrate 11 absorbs photons, and can conduct them to the main body 18 connected to itself, without the collected carriers being unable to be extracted due to its own discreteness, thereby improving the carrier collection capacity of the electrode structure.

[0096] Specifically, Figure 7As shown, the boundary of the continuous transition portion 19 away from the main body 18 can be roughly parallel to the boundary of the main body 18. When the angle between the boundary of the continuous transition portion 19 away from the main body 18 and the boundary of the main body 18 is greater than 0 and less than or equal to A° (A° can be 5°, for example), it can be considered that the boundary of the continuous transition portion 19 away from the main body 18 is roughly parallel to the boundary of the main body 18. In this case, along the length extension direction of each electrode, the width of each part of the continuous transition portion 19 is roughly the same, so that the continuous transition portion 19 is the electrode. The degree of improvement in the adhesion of each part of the electrode along the length direction on the surface of the electrode substrate is roughly the same, ensuring the structural stability of each part of the electrode along the length direction; at the same time, it can also make the degree of improvement in the conductivity of each part of the continuous transition portion 19 to the electrode be roughly the same, so that each part of the electrode has roughly the same carrier collection ability, which is conducive to making each part of the battery substrate 11 of the solar cell have a balanced number of carriers in the working state, reducing the probability of recombination due to uneven carrier distribution, and thus helping to improve the photoelectric conversion efficiency of the solar cell.

[0097] Of course, the boundary of the continuous transition portion away from the main body may not be substantially parallel to the boundary of the main body. In this case, the angle between the boundary of the continuous transition portion away from the main body and the boundary of the main body can be determined according to the actual application scenario, and is not specifically limited here.

[0098] In addition, the surface of the continuous transition portion facing away from the main body portion may be arranged vertically relative to the horizontal plane. Figure 8 and Fig. 9 As shown, the surface of the continuous transition portion 19 away from the main body 18 can also be inclined relative to the horizontal plane. In this case, the height of the electrode on both sides along the width direction gradually decreases, so that the transition of the electrode with a certain height on both sides along the width direction relative to the first surface 12 is smoother, which can improve the mechanical strength of the electrode and reduce the risk of electrode breakage. In addition, the surface of the continuous transition portion 19 away from the main body 18 is inclined relative to the horizontal plane, which can make the surface of the continuous transition portion 19 away from the main body 18 have a certain reflection effect on the light on the side of the first surface 12, and part of the light reflected by it is refracted into the second surface, which is beneficial to improve the utilization rate of light by solar cells.

[0099] Wherein, along the width direction of the main body and in the direction away from the main body, the height of each position of the continuous transition portion gradually decreases, which can be: the rate of change of the height gradually decreases is approximately the same. Alternatively, along the width direction of the main body and in the direction away from the main body, the rate of change of the height of some areas of the continuous transition portion is approximately the same, while the height of the remaining areas decreases significantly. For example: the rate of change of the height of the area adjacent to the main body of the continuous transition portion is approximately the same, while the height of the part that is more than a preset distance away from the main body decreases significantly.

[0100] Specifically, when the surface of the continuous transition portion away from the main body is inclined relative to the horizontal plane, the angle between the surface of the continuous transition portion away from the main body and the horizontal plane can be determined according to the actual manufacturing process and actual application scenario, and is not specifically limited here.

[0101] Exemplarily, the angle between the surface of the continuous transition portion away from the main body and the horizontal plane is greater than or equal to 45° and less than 90°. For example, the angle may be 45°, 50°, 60°, 70°, 80° or 85°, etc. In this case, the angle between the surface of the continuous transition portion away from the main body and the horizontal plane is within the above range, which can prevent the steepness of the transition of the two sides of the electrode along the width direction relative to the second surface due to the large angle, thereby ensuring that the electrode has a high mechanical strength. In addition, it can also prevent the continuous transition portion from extending too wide along the width direction of the main body due to the small angle, thereby reducing the shading area of ​​the continuous transition portion on the first surface, which is conducive to allowing more light to be refracted into the battery substrate through the first surface, further improving the photoelectric conversion efficiency of the solar cell.

[0102] Furthermore, the embodiment of the present invention does not specifically limit the size of the main body and the continuous transition portion, which can be determined according to the actual application scenario.

[0103] Exemplarily, the width of the continuous transition portion may be greater than or equal to 1 μm and less than or equal to 15 μm. For example, the width of the continuous transition portion may be 1 μm, 3 μm, 6 μm, 9 μm, 12 μm or 15 μm, etc. The beneficial effects in this case can be analyzed with reference to the beneficial effects of the angle between the surface of the continuous transition portion away from the main body and the horizontal plane being greater than or equal to 45° and less than 90° as described above, which will not be repeated here.

[0104] Exemplarily, the thickness of the main body may be greater than or equal to 500nm and less than or equal to 30μm. For example, the thickness of the main body may be 500nm, 1μm, 10μm, 20μm or 30μm, etc. In this case, the thickness of the main body included in each electrode is within the above range, which can prevent the transmission resistance of the electrode from being high due to the small thickness of the main body included in the electrode when the electrode width is constant, thereby ensuring that the electrode structure has good conductivity. At the same time, it can also prevent the large amount of consumables used in the electrode structure and the long process cycle due to the large thickness of the main body included in the electrode, which is beneficial to control the manufacturing cost of solar cells and improve the process efficiency of solar cells.

[0105] Exemplarily, the width of the main body may be greater than or equal to 10 μm and less than or equal to 500 μm. For example, the width of the main body may be 10 μm, 100 μm, 200 μm, 300 μm, 400 μm or 500 μm, etc. In this case, the width of the main body included in each electrode is within the above range, which can prevent the electrode from easily collapsing during manufacturing or interconnection due to the large thickness-to-width ratio of the electrode without increasing the resistance due to the small width of the main body, thereby improving the structural stability of the electrode. At the same time, it can also prevent the electrode from having a large shading area due to a large width, thereby ensuring that the solar cell has a high photoelectric conversion efficiency.

[0106] In addition, if Fig.11 As shown, the electrode structure 13 is a solid structure without pores. Of course, in some examples, in the actual electrode preparation process, there may be a small number of micro pores in the electrode structure 13. This is because there may be impurities and air leakage in the process chamber during the manufacture of the electrode structure 13. The pores are different from the pores generated by the volatilization of organic materials in the electrode slurry during the sintering process when the screen-printed electrode is manufactured.

[0107] It can be understood that when the electrode structure in the solar cell provided in the embodiment of the present invention is manufactured by vacuum coating, the materials used to manufacture the electrode structure do not include volatile organic materials used in the manufacture of silk-screen electrodes; and the chamber cleanliness of the electrode structure in the solar cell provided in the embodiment of the present invention is high and there is no air leakage, which is conducive to making the manufactured electrode structure free of pores.

[0108] In the case where the electrode structure is a solid structure without pores, such as Fig.11 and Fig.12 As shown, compared with the existing electrode structure with pores 20, each region of the electrode structure in the embodiment of the present invention can effectively conduct carriers, which is conducive to improving the conductivity of each region of the electrode structure. At the same time, the mechanical strength of the electrode structure can also be improved, reducing the risk of problems such as breakage or bending during the interconnection process between the electrode structure and the interconnection part or during actual use.

[0109] Among them, the internal characteristics of the electrode structure can be determined according to manufacturing parameters such as the deposition rate of the electrode structure, and the type of manufacturing process, etc., and are not specifically limited here.

[0110] In a second aspect, an embodiment of the present invention further provides a photovoltaic module, which includes the solar cell provided by the first aspect and various implementations thereof.

[0111] The beneficial effects of the second aspect in the embodiments of the present invention can be analyzed by referring to the beneficial effects of the first aspect and its various implementations, and will not be repeated here.

[0112] In a third aspect, an embodiment of the present invention further provides a method for manufacturing a solar cell, the method comprising: first, forming a polymer mask provided with an electrode pattern. Next, transferring and fixing the polymer mask on a first surface of a battery substrate. Next, under the protection of the polymer mask, forming an electrode structure on the first surface by vacuum coating. The surface of the electrode structure facing away from the battery substrate is the second surface. Both the first surface and the second surface are velvet, and the height of each position of the second surface increases as the height of the corresponding position of the first surface increases, and the height of each position of the second surface decreases as the height of the corresponding position of the first surface decreases.

[0113] Specifically, the polymer mask provided with the electrode pattern can be formed by laser etching or the like. Among them, because laser etching has a high etching accuracy, when the polymer mask is formed by laser etching, the accuracy of the electrode pattern provided in the polymer mask layer can be improved, thereby improving the manufacturing accuracy of the electrode structure. In addition, the material of the polymer mask can include at least one polymer material such as PET, PMMA or PDMS that can be applied to the manufacturing method provided in the embodiment of the present invention. Secondly, after the polymer mask is transferred to the first surface of the battery substrate, the polymer mask can be fixed to the battery substrate by a combination of one or more of double-sided tape, glue, a fixed card slot, and a wafer stage. Among them, the area of ​​the battery substrate exposed outside the polymer mask is the area where the electrode structure is desired to be formed.

[0114] Furthermore, the above-mentioned vacuum coating method may include processes such as evaporation, sputtering, ion plating or vacuum winding coating. Based on this, at least one coating process included in the vacuum coating method can be used to form an electrode structure on the first side of the battery substrate. Information such as the structure of the electrode structure and the morphology of the electrode structure can be referred to the previous text and will not be repeated here. As for the process parameters when forming the electrode structure, in the actual manufacturing process, the size of the coating parameters that affect the morphology of the second side of the electrode structure can be adjusted to achieve the morphology of the second side of the manufactured electrode structure according to the requirements of the actual application scenario. Specifically, the parameters that can regulate the morphology of the second side of the electrode structure include deposition rate, etc., and the size of the above-mentioned control parameters can be determined according to actual needs.

[0115] Exemplarily, the deposition rate of the electrode structure formed on the first surface by the vacuum coating method can be greater than 0 and less than or equal to 1nm / s. For example, the deposition rate can be 0.1nm / s, 0.2nm / s, 0.4nm / s, 0.6nm / s, 0.8nm / s or 1nm / s, etc. In this case, in the actual manufacturing process, within a certain range, the deposition rate is proportional to the deposition defects. Therefore, when the deposition rate of the electrode structure on the first surface of the battery substrate is within the above range, the deposition rate of the electrode structure on the first surface is relatively small, which is conducive to reducing the defects in the manufactured electrode structure, and is conducive to making the second surface of the electrode structure maintain substantially the same morphological features as the first surface, ensuring that the second surface of the manufactured electrode structure has substantially the same surface roughness as the first surface.

[0116] The beneficial effects of the third aspect of the embodiment of the present invention can refer to the beneficial effects analysis in the first aspect and its various implementation methods, and will not be repeated here. In addition, it should be noted that the manufacturing method provided by the embodiment of the present invention is to manufacture the electrode structure by vacuum coating. At this time, the electrode structure can be manufactured by metal conductive materials such as copper or aluminum whose price is lower than silver, so as to control the manufacturing cost of the electrode structure. In addition, in the process of forming the electrode structure by vacuum coating, water and other liquids will not be contacted throughout the process, so there is no need to treat wastewater. Furthermore, the polymer mask and the battery substrate are in contact through chemical bonds such as van der Waals forces or hydrogen bonds, so that the contact sealing between the two is higher, so that the situation of slurry penetration due to the loose contact between the silk screen screen and the battery substrate can be solved, and the manufacturing accuracy of the electrode structure can be improved. Moreover, after the electrode structure is formed, the polymer mask can be directly removed by mechanical means, without the need to remove the mask by chemical corrosion, which will affect the electrode structure, ensuring that the electrode structure has a high formation quality.

[0117] Secondly, the embodiment of the present invention also provides a specific embodiment implemented by the manufacturing method provided by the present invention, and two comparative examples implemented by the prior art to illustrate the specific conditions of the electrode structure manufactured in the embodiment of the present invention: wherein the manufacturing method provided in embodiment 1 is to manufacture the electrode structure included in the solar cell by vacuum coating. Specifically, Fig.13 and Fig.14 As shown, the first surface of the solar cell substrate and the second surface of the electrode structure are both pyramid-shaped velvet structures. Fig.13 FIG. 1 is a schematic diagram showing a structure of a solar cell having an electrode structure formed on one side thereof when the velvet surface is a pyramid-shaped velvet surface in an embodiment of the present invention, which is magnified 1000 times. Fig.14 A schematic diagram showing a structure at the second surface of the electrode structure magnified 5000 times when the suede surface is a pyramid-shaped suede surface in an embodiment of the present invention.

[0118] Secondly, if Fig.15 and Fig.16 As shown, comparative example 1 is to use the existing screen printing process to manufacture the electrode structure. Fig.15 The schematic diagram shows a structure of a solar cell having an electrode structure formed on one side thereof when the solar cell is manufactured by screen printing and the velvet surface is a pyramid-shaped velvet surface, which is magnified 1000 times. Fig.16 A schematic diagram showing a structure at the second surface of an electrode structure magnified 5000 times when the structure is manufactured using a screen printing process and the velvet surface is a pyramid-shaped velvet surface.

[0119] In addition, if Fig.17 and Fig.18 As shown, comparative example 2 is to use the existing electroplating process to manufacture the electrode structure. Fig.17 The schematic diagram shows a structure of a solar cell with an electrode structure formed on one side thereof when the solar cell is manufactured by electroplating process and the velvet surface is a pyramid-shaped velvet surface, which is magnified 1000 times. Fig.18 A schematic diagram showing a structure at the second surface of an electrode structure magnified 5000 times when the structure is manufactured by electroplating process and the velvet surface is a pyramid-shaped velvet surface.

[0120] Except that the manufacturing method of the electrode structure is different from that of the electrode structure in Example 1, all other aspects of Comparative Examples 1 and 2 are the same.

[0121] Table 1 observes the solar cells manufactured by the above-mentioned Example 1, Comparative Example 1 and Comparative Example 2, and compares the roughness of the second surface of the electrode structure of the above-mentioned three solar cells.

[0122] Table 1: Comparison of the roughness of the second surface of the electrode structure in the solar cell manufactured in Comparative Examples 1 and 2 and Example 1

[0123]

[0124] It can be seen from the data shown in Table 1 that in the second surface of the electrode structure, within the small range of every 1 μm, every 5 μm and every 10 μm, the roughness of the second surface of the electrode structure in the solar cell manufactured in the embodiment is higher than the roughness of the second surface of the electrode structure corresponding to the solar cell manufactured by Comparative Example 1 and Comparative Example 2. And, within the large range of 100 μm, the roughness of the second surface of the electrode structure in the solar cell manufactured in the embodiment is lower than the roughness of the second surface of the electrode structure corresponding to the solar cell manufactured by Comparative Example 1. Based on this, the connection strength between the electrode structure and the interconnection of the solar cell manufactured in the embodiment is higher than the connection strength between the electrode structure and the interconnection of the solar cell manufactured in Comparative Example 1 and Comparative Example 2. And, the uniformity of the connection tension between the electrode structure and the interconnection of the solar cell manufactured in the embodiment is better than the uniformity of the connection tension between the electrode structure and the interconnection of the solar cell manufactured in Comparative Example 1.

[0125] It should be noted that surface roughness refers to the unevenness of the surface with small spacing and tiny peaks and valleys. Based on this, in the second surface of the electrode structure corresponding to the solar cell manufactured in the above embodiment, the roughness within every 1 μm range and every 5 μm range is smaller than the roughness within 10 μm range, because the velvet structure on the second surface of the electrode structure has a certain size. When determining the roughness within a small range (such as within every 1 μm range and within every 5 μm range), if the small range is defined without covering the peaks and valleys of the velvet structure, the roughness within the small range will be smaller. A large range (such as within 10 μm range) can define at least one or more velvet structures within its boundaries, so the roughness of the large range will be greater than the roughness of the small range.

[0126] In the above description, the technical details of the patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of desired shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not completely the same as the methods described above. In addition, although the various embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage.

[0127] The embodiments of the present disclosure are described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, a person skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A solar cell, characterized in that: include: A battery substrate, and an electrode structure formed on the battery substrate; wherein, The surface on which the electrode structure is formed on the battery substrate is the first surface, and the surface on the side of the electrode structure facing away from the battery substrate is the second surface; the first surface and the second surface are both velvet surfaces; the height of each position of the second surface increases as the height of the corresponding position of the first surface increases, and the height of each position of the second surface decreases as the height of the corresponding position of the first surface decreases.

2. The solar cell according to claim 1, characterized in that: When the thickness of the electrode structure is greater than or equal to 0.5 μm and less than or equal to 15 μm, the thickness of the electrode structure at each position is the same; When the thickness of the electrode structure is greater than 15 μm and less than or equal to 50 μm, the thickness of the electrode structure at the recessed position is greater than the thickness of the electrode structure at the raised position.

3. The solar cell according to claim 1, characterized in that The suede surface is a pyramid-shaped suede surface.

4. The solar cell according to claim 3, characterized in that: The average base size of the pyramid-shaped protrusion structures on the first surface and the second surface is greater than or equal to 0.5 μm and less than or equal to 10 μm.

5. The solar cell according to any one of claims 1 to 4, characterized in that: The roughness of the second surface within a range of 10 μm is greater than 170 nm and less than or equal to 900 nm; The roughness of the second surface per 100 μm is greater than or equal to 200 nm and less than or equal to 900 nm.

6. The solar cell according to any one of claims 1 to 4, characterized in that: The second surface is composed of granular conductive protrusions, and there is no gap between adjacent conductive protrusions.

7. The solar cell according to claim 6, characterized in that: The size of the conductive protrusion is greater than or equal to 100 nm and less than or equal to 2000 nm.

8. The solar cell according to any one of claims 1 to 4, characterized in that: The electrode structure includes a plurality of electrodes, each of which has a main body and continuous transition portions located on both sides of the main body along a width direction; an average height of the main body is greater than an average height of the continuous transition portions.

9. The solar cell according to claim 8, characterized in that The boundary of the continuous transition portion facing away from the main body portion is substantially parallel to the boundary of the main body portion.

10. The solar cell according to claim 8, characterized in that The width of the continuous transition portion is greater than or equal to 1 μm and less than or equal to 15 μm; and / or, The angle between the surface of the continuous transition portion away from the main body and the horizontal plane is greater than or equal to 45° and less than 90°; and / or, Along the width direction of the main body and away from the main body, the height of each position of the continuous transition portion gradually decreases; and / or, The thickness of the main body is greater than or equal to 500 nm and less than or equal to 30 μm; and / or, The width of the main body is greater than or equal to 10 μm and less than or equal to 500 μm.

11. The solar cell according to any one of claims 1 to 4, characterized in that: The electrode structure comprises a collector electrode and a bus electrode which are integrally formed and cross-arranged.

12. The solar cell according to any one of claims 1 to 4, characterized in that: An absolute value of a difference between the roughness of the first surface and the roughness of the second surface is greater than or equal to 0.5 μm and less than or equal to 5 μm.

13. A photovoltaic module, characterized in that: The invention comprises a solar cell as claimed in any one of claims 1 to 12.

14. A method for manufacturing a solar cell, characterized in that: include: forming a polymer mask provided with an electrode pattern; Transferring and fixing the polymer mask onto the first surface of the battery substrate; Under the protection of the polymer mask, an electrode structure is formed on the first surface by vacuum coating; the surface of the electrode structure facing away from the battery substrate is the second surface; the first surface and the second surface are both velvet surfaces, and the height of each position of the second surface increases as the height of the corresponding position of the first surface increases, and the height of each position of the second surface decreases as the height of the corresponding position of the first surface decreases.

15. The method for manufacturing a solar cell according to claim 14, characterized in that: The deposition rate of forming the electrode structure on the first surface by the vacuum coating method is greater than 0 and less than or equal to 1 nm / s.

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