Solar cell, preparation method thereof and photovoltaic equipment

Abstract

The invention provides a solar cell, a preparation method thereof and photovoltaic equipment. The method for preparing the solar cell comprises the following steps: forming a patterned conductive seed layer on a light-facing surface and / or a backlight surface of a cell main body; a conductive wire is fixed on one side, far away from the battery main body, of the patterned conductive seed layer, and a preset gap is formed between the conductive wire and the patterned conductive seed layer; and electroplating at the predetermined gap to form a conductive connection layer, wherein the conductive connection layer is in contact connection with the patterned conductive seed layer and the conductive wire. Therefore, in the method for preparing the solar cell, the conductive connecting layer is formed between the conductive wire and the patterned conductive seed layer through electroplating, so that the conductive wire and the conductive connecting layer as well as the conductive connecting layer and the patterned conductive seed layer are electrically connected through contact, and a low-temperature electroplating process is adopted to replace a high-temperature welding process; and negative effects on the battery caused by high temperature in the welding process can be effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more specifically, to solar cells, their fabrication methods, and photovoltaic devices. Background Technology

[0002] To reduce power generation losses in solar cells, a current collection path can be designed using tandem grid technology. Tandem grid cells innovatively combine the grid lines and solder strips into one. Specifically, a seed layer is first printed on the cell surface, and then fine conductive filaments are soldered to the seed layer. Connecting the fine conductive filaments of two cells allows current to be transferred between them. Therefore, the current transmission path of a tandem grid solar cell is as follows: current is transmitted through the semiconductor of the solar cell to the seed layer, then directly from the seed layer to the fine conductive filaments, and then along the fine conductive filaments. Tandem grid technology shortens the current transmission path, reduces current transmission losses, and improves the conversion efficiency of photovoltaic modules. However, tandem grid technology uses high-temperature welding to connect the fine conductive filaments to the seed layer. This high-temperature welding process can bring some negative effects to solar cells, such as residual thermal stress and the risk of solder joint breakage. Summary of the Invention

[0003] This invention aims to at least partially address one of the technical problems in related technologies. Therefore, one object of this invention is to provide a method for fabricating solar cells, in which the connection between conductive wires and a conductive seed layer achieved through a low-temperature electroplating process helps to improve the performance of the solar cell.

[0004] In one aspect of the invention, a method for fabricating the aforementioned solar cell is provided. According to an embodiment of the invention, the method for fabricating a solar cell includes: forming a patterned conductive seed layer on the light-facing and / or back-facing side of a cell body; fixing a conductive wire to the patterned conductive seed layer on a side away from the cell body, with a predetermined gap between the conductive wire and the patterned conductive seed layer; and electroplating a conductive connection layer at the predetermined gap, wherein the conductive connection layer is in contact with both the patterned conductive seed layer and the conductive wire. Thus, in this method for fabricating a solar cell, a conductive connection layer is formed between the conductive wire and the patterned conductive seed layer through electroplating, thereby achieving electrical connection between the conductive wire and the conductive connection layer, and between the conductive connection layer and the patterned conductive seed layer, through contact. Furthermore, the use of a low-temperature electroplating process instead of a high-temperature welding process effectively avoids the negative impact of high temperatures during welding on the cell.

[0005] According to an embodiment of the present invention, a method for fixing the conductive wire includes: providing a mold having a recessed region, the bottom of the recessed region having at least one groove, disposing the conductive wire in the groove, wherein there is a height difference between the surface of the conductive wire facing the battery body and the bottom of the recessed region, and the surface of the conductive wire does not extend beyond the bottom surface of the recessed region, the battery body is disposed in the recessed region and conforms to the bottom plane of the recessed region, and the predetermined gap exists between the conductive wire and the patterned conductive seed layer.

[0006] According to an embodiment of the present invention, the conductive filament serves as the cathode, and the conductive connection layer is grown from the conductive filament toward the conductive seed layer until the conductive connection layer is connected to the patterned conductive seed layer.

[0007] According to an embodiment of the present invention, the patterned conductive seed layer serves as a cathode, and the conductive connection layer is grown from the patterned conductive seed layer toward the conductive filament until the conductive connection layer is connected to the conductive filament.

[0008] According to an embodiment of the present invention, the conductive connection layer covers the surface of the conductive wire near the battery body.

[0009] According to an embodiment of the present invention, the orthographic projection of the conductive connection layer on the battery body lies within the orthographic projection of the patterned conductive seed layer on the battery body.

[0010] According to an embodiment of the present invention, the spacing of the predetermined gap is equal to the thickness of the conductive connection layer.

[0011] According to an embodiment of the present invention, the thickness of the conductive connection layer is 20 to 200 micrometers, and / or the material of the conductive connection layer includes at least one of copper and silver.

[0012] In another aspect, the present invention provides a solar cell prepared by the method described above. This solar cell exhibits good performance and excellent stability. Those skilled in the art will understand that this solar cell possesses all the features and advantages of the methods described above for preparing solar cells, which will not be elaborated upon further here.

[0013] In another aspect, the present invention provides a photovoltaic device. According to an embodiment of the invention, the photovoltaic device includes the solar cell described above, or includes a solar cell prepared by the methods described above. Therefore, the photovoltaic device has better cell efficiency and better circuit stability. Those skilled in the art will understand that the photovoltaic device possesses all the features and advantages of the solar cell described above, which will not be elaborated further here.

[0014] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0015] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart of the fabrication of a solar cell in one embodiment of the present invention; Figure 2 This is a partial flowchart of the fabrication of a solar cell in another embodiment of the present invention; Figure 3 This is a schematic diagram of the mold structure in another embodiment of the present invention; Figure 4 This is a schematic diagram of a conductive wire being placed in a mold in another embodiment of the present invention; Figure 5 yes Figure 4 Cross-sectional view along AA'. Detailed Implementation

[0016] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.

[0017] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0018] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0019] Current stacked grid technology typically uses high-temperature welding to attach conductive wires to the seed layer on the surface of solar cells. This high-temperature process results in significant thermal stress between the conductive wires, electrodes, and cells due to thermal deformation, posing a substantial risk of failure during subsequent use. Conductive wire detachment or breakage can lead to a significant drop in output power. Furthermore, the high-temperature process primarily relies on solder to form an alloy with the electrode metal for circuit connections. However, the tensile and yield strength of this alloy layer is far lower than that of the conductive wire itself, making the welded area relatively weak in resisting stress and prone to solder joint breakage, resulting in reduced cell power. Additionally, the solder alloy has poor conductivity, leading to significant current loss through the solder joint area.

[0020] In one aspect of the invention, a method for preparing the aforementioned solar cell is provided. According to an embodiment of the invention, referring to... Figure 1 and Figure 2 Methods for preparing solar cells include: S100: A patterned conductive seed layer 200 is formed on the light-facing surface 110 and / or the back-facing surface 120 of the battery body 100 (the example shown is that it is set on the surface of the light-facing surface 110).

[0021] According to some embodiments of the present invention, the type of battery body is not limited, and those skilled in the art can make flexible selections according to actual needs. In some embodiments, the battery body can be a TOPCon (tunneling oxide passivated contact) battery, a BC (back contact) battery, an HJT (heterojunction) battery, or a crystalline silicon-perovskite tandem battery containing the above-mentioned crystalline silicon battery, etc.

[0022] According to some embodiments of the present invention, there are no specific limitations on the method for preparing the patterned conductive seed layer 200, and those skilled in the art can flexibly design and select methods based on existing technology and actual needs. In some embodiments, inkjet printing, screen printing, photoresist patterning, and other processes can be used for preparation.

[0023] When fabricating the patterned conductive seed layer 200 using a photoresist patterning process, the method may include: preparing a complete conductive seed layer by deposition (e.g., chemical vapor deposition, physical vapor deposition (compared to magnetron sputtering)); coating a complete negative photoresist layer on the surface of the complete conductive seed layer; exposing the negative photoresist layer at the corresponding locations where the patterned conductive seed layer needs to be formed; then developing the unexposed areas to expose the surface of the complete conductive seed layer corresponding to those areas; finally etching away the exposed seed layer portion using a strong alkali or strong acid to obtain the patterned conductive seed layer 200; and finally removing the photoresist. In other embodiments, a positive photoresist may be used to prepare the patterned conductive seed layer.

[0024] According to some embodiments of the present invention, the material of the patterned conductive seed layer includes at least one of copper, nickel, silver, and tin. Therefore, the above materials have good conductivity, enabling efficient current transmission and reducing energy loss. In some embodiments, the thickness of the patterned conductive seed layer is less than 500 nm, which can reduce recombination loss and optical loss, while also lowering costs.

[0025] S200: A conductive wire 400 is fixed on the side of the patterned conductive seed layer 200 away from the battery body 100, and there is a predetermined gap between the conductive wire 400 and the patterned conductive seed layer 200.

[0026] According to some embodiments of the present invention, with reference to Figure 1 and Figure 2 The method for fixing the conductive wire includes fixing the conductive wire 400 in the mold 410 and exposing the surface of the conductive wire 400 near the battery body 100. This results in a better fixing effect without adversely affecting the conductive wire or the subsequent formation of the conductive connection layer.

[0027] In some embodiments, refer to Figure 3 , Figure 4 and Figure 5 The method for fixing the conductive wire includes: providing a mold 410, the mold 410 having a recessed region 411, the bottom 413 of the recessed region 411 having at least one groove 412, and placing the conductive wire 400 in the groove 412. A height difference h exists between the surface of the conductive wire 400 facing the battery body 100 and the bottom 413 of the recessed region 411, and the surface of the conductive wire 400 does not extend beyond the bottom surface 413 of the recessed region 411. The battery body 100 is placed in the recessed region 411 and conforms to the plane of the bottom 413 of the recessed region 411. A predetermined gap exists between the conductive wire 400 and the patterned conductive seed layer 200. This effectively fixes the conductive wire and the battery body, ensuring the stability of the subsequent electroplating process and thus improving the yield of the conductive connection layer.

[0028] According to some embodiments of the present invention, with reference to Figure 1 and Figure 2 The spacing h of the predetermined gap is equal to the thickness of the conductive connection layer to be formed. This improves the fabrication precision and yield of the conductive connection layer, and ensures good contact between the conductive connection layer and the conductive wire and patterned conductive seed layer, thereby improving the contact yield between layer structures and enhancing the current transmission efficiency in the circuit.

[0029] According to some embodiments of the present invention, the mold is made of an insulating material, thereby preventing the mold from being energized with the conductive wire and preventing the electroplated conductive bonding layer material from forming on the mold. In some specific embodiments, the mold material can be insulating materials such as ceramics or glass.

[0030] According to some embodiments of the present invention, the conductive wire is made of at least one of copper, nickel, silver, and tin. Conductive wires made of the above materials have good conductivity, which can improve current transmission efficiency and reduce energy loss; moreover, they have good corrosion resistance and good mechanical properties such as tensile strength and bending resistance.

[0031] According to some embodiments of the present invention, there are no limitations on the corresponding placement of the conductive wire, and those skilled in the art can flexibly design the position of the conductive wire according to actual needs.

[0032] S300: A conductive connection layer 300 is formed by electroplating at a predetermined gap. The conductive connection layer 300 is in contact with the patterned conductive seed layer 200 and the conductive wire 400.

[0033] In the above steps, the use of electroplating, a low-temperature process, to form a conductive connection layer can avoid the thermal stress caused by high-temperature processes (such as high-temperature welding), thereby helping to improve the quality and output power of solar cells. The conductive connection layer formed by electroplating has better strength and good and stable contact with conductive wires and patterned conductive seed layers, which can effectively reduce functional losses.

[0034] According to some embodiments of the present invention, a specific method for electroplating to form a conductive connection layer can be implemented by one of the following methods: According to some embodiments of the present invention, with reference to Figure 1 A patterned conductive seed layer 200 is energized, serving as the cathode. A conductive connection layer is grown on the exposed surface of the seed layer near the conductive wire using electroplating. When the conductive connection layer grows to the point of just contacting the conductive wire 400, the conductive wire 400 also connects to the cathode. Further electroplating allows the reduced metal to fill the micro-gaps between the conductive connection layer and the conductive wire 400, thus forming a strong mechanical and stable electrical connection between the conductive connection layer 300 and the conductive wire 400.

[0035] In some embodiments, refer to Figure 1 When the patterned conductive seed layer 200 is energized, the orthographic projection of the formed conductive connection layer 300 on the battery body 100 lies within the orthographic projection of the patterned conductive seed layer 200 on the battery body 100. Specifically, the orthographic projection of the conductive connection layer 300 on the battery body 100 may overlap with the orthographic projection of the patterned conductive seed layer 200 on the battery body 100, meaning the pattern of the conductive connection layer and the patterned conductive seed layer is consistent. Alternatively, the orthographic projection of the conductive connection layer 300 on the battery body 100 may lie within the orthographic projection of the patterned conductive seed layer 200 on the battery body 100, and the area of ​​the orthographic projection of the conductive connection layer 300 on the battery body 100 may be smaller than the area of ​​the orthographic projection of the patterned conductive seed layer 200 on the battery body 100. Therefore, the conductive connection layer 300 and the patterned conductive seed layer 200 have a better contact area, which can improve the contact effect between the layer structures, improve current transmission efficiency, reduce energy loss, and reduce the risk of circuit malfunctions. The aforementioned “overlap” includes the case where the orthographic projections of the conductive connection layer 300 and the patterned conductive seed layer 200 completely overlap, as well as the case where complete overlap is impossible due to unavoidable operational errors in the process, but overall the orthographic projections of the two basically overlap.

[0036] According to other embodiments of the present invention, refer to Figure 2 A conductive wire 400 is energized, serving as the cathode. A conductive connection layer is grown on the surface of the conductive wire using electroplating. The conductive connection layer grows from the conductive wire 400 towards the conductive seed layer 210 in the gap between the exposed conductive seed layer 210 and the conductive wire 400. When the conductive connection layer grows to the point of just contacting the conductive seed layer 210, the conductive seed layer 210 is electrically connected to the cathode. Further electroplating allows the reduced metal to fill the micro-gap between the conductive connection layer and the conductive seed layer 210, thereby forming a strong mechanical connection and a stable electrical connection between them.

[0037] In some embodiments, refer to Figure 2 The formed conductive connection layer 300 covers the surface of the conductive wire 400 near the battery body 100. The conductive connection layer 300 is attached to the surface of the conductive wire 400, which can improve the contact yield between the conductive wire 400 and the conductive connection layer 300, improve the contact surface between the conductive connection layer 300 and the patterned conductive seed layer 200, and thus improve the contact yield between the patterned conductive seed layer 200 and the conductive connection layer 300, thereby improving the current transmission efficiency in the circuit.

[0038] In the aforementioned example, the conductive wire 400 or the patterned conductive seed layer 200 can be connected to the cathode, while the material of the conductive connection layer serves as the anode. Specifically, when the conductive connection layer is copper, pure copper is used as the anode, and a salt solution containing copper ions is used as the electrolyte. When the conductive connection layer is silver, pure silver is used as the anode, and a salt solution containing silver ions is used as the electrolyte.

[0039] Preferably, the conductive bonding layer is copper, pure copper is the anode, and a salt solution containing copper ions is the electrolyte.

[0040] In the above embodiments, the copper salt can be copper sulfate, copper nitrate, copper chloride, or other copper salts. During electroplating, the concentration of the copper salt can be 0.5-5 mol / L, and the current density can be 0.5-5.0 A / dm².

[0041] In some embodiments, after forming the conductive connection layer 300, the conductive wire 400 is demolded to obtain a solar cell.

[0042] According to some embodiments of the present invention, the conductive connection layer is made of at least one of copper and silver. Therefore, the conductive connection layer made of the above-mentioned materials exhibits superior conductivity, is widely available, and is easier to manufacture. In some embodiments, the conductive connection layer is made of copper, which results in lower cost and better conductivity.

[0043] According to some embodiments of the present invention, the thickness of the conductive connection layer is 20-200 micrometers (i.e., the spacing of the predetermined gap is 20-200 micrometers), such as 20 micrometers, 40 micrometers, 50 micrometers, 60 micrometers, 80 micrometers, 100 micrometers, 120 micrometers, 140 micrometers, 150 micrometers, 180 micrometers, 200 micrometers, etc. Conductive connection layers of the above thicknesses are easy to fabricate and have good contact with the conductive wire and the patterned conductive seed layer, enabling efficient current transmission. Furthermore, the thinner conductive connection layer can reduce light loss; simultaneously, it facilitates control of the predetermined gap spacing.

[0044] According to an embodiment of the present invention, in this method for preparing a solar cell, a conductive connection layer is formed between the conductive wire and the patterned conductive seed layer by electroplating, thereby enabling electrical connection between the conductive wire and the conductive connection layer, and between the conductive connection layer and the patterned conductive seed layer, through contact. Moreover, the use of a low-temperature electroplating process instead of a high-temperature welding process can avoid the negative impact of high temperatures during welding on the cell. For example, using a low-temperature electroplating process to form the conductive connection layer can avoid the thermal stress caused by high-temperature processes (such as high-temperature welding), thereby helping to improve the quality and output power of the solar cell. The conductive connection layer formed by electroplating has better strength and good contact with the conductive wire and the patterned conductive seed layer, which can effectively reduce functional losses.

[0045] In another aspect, the present invention provides a solar cell prepared by the method described above. This solar cell exhibits good performance and excellent stability. Those skilled in the art will understand that this solar cell possesses all the features and advantages of the methods described above for preparing solar cells, which will not be elaborated upon further here.

[0046] In the solar cell prepared by the present invention, the grid stacking technology is used. The current is transmitted through the semiconductor of the solar cell to the patterned conductive seed layer 200, and then from the patterned conductive seed layer 200 through the conductive connection layer 300 to the conductive wire 400, and then along the conductive wire 400.

[0047] According to some embodiments of the present invention, with reference to Figure 1 The orthographic projection of the conductive connection layer 300 on the battery body 100 lies within the orthographic projection of the patterned conductive seed layer 200 on the battery body 100. Specifically, the orthographic projection of the conductive connection layer 300 on the battery body 100 may overlap with the orthographic projection of the patterned conductive seed layer 200 on the battery body 100, meaning the patterns of the conductive connection layer and the patterned conductive seed layer are consistent. Alternatively, the orthographic projection of the conductive connection layer 300 on the battery body 100 may lie within the orthographic projection of the patterned conductive seed layer 200 on the battery body 100, and the area of ​​the orthographic projection of the conductive connection layer 300 on the battery body 100 may be smaller than the area of ​​the orthographic projection of the patterned conductive seed layer 200 on the battery body 100.

[0048] According to other embodiments of the present invention, refer to Figure 2 The conductive connection layer 300 covers the surface of the conductive wire 400 near the battery body 100, which can improve the contact yield between the conductive wire 400 and the conductive connection layer 300, improve the contact surface between the conductive connection layer 300 and the patterned conductive seed layer 200, and thus improve the contact yield between the patterned conductive seed layer 200 and the conductive connection layer 300, thereby improving the current transmission efficiency in the circuit.

[0049] In another aspect, the present invention provides a photovoltaic device. According to an embodiment of the invention, the photovoltaic device includes the solar cell described above, or includes a solar cell prepared by the methods described above. Therefore, the photovoltaic device has better cell efficiency and better circuit stability. Those skilled in the art will understand that the photovoltaic device possesses all the features and advantages of the solar cell described above, which will not be elaborated further here.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0051] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a solar cell, characterized in that, include: A patterned conductive seed layer is formed on the light-facing and / or back-facing surfaces of the battery body; A conductive wire is fixed on the side of the patterned conductive seed layer away from the battery body, and there is a predetermined gap between the conductive wire and the patterned conductive seed layer; A conductive connection layer is formed by electroplating at the predetermined gap, and the conductive connection layer is in contact with the patterned conductive seed layer and the conductive wire.

2. The method according to claim 1, characterized in that, The method for fixing the conductive wire includes: A mold is provided, the mold having a recessed area, the bottom of the recessed area having at least one groove; The conductive wire is disposed in the groove, wherein there is a height difference between the surface of the conductive wire facing the battery body and the bottom of the recessed area, and the surface of the conductive wire does not extend beyond the bottom surface of the recessed area. The battery body is disposed in the recessed area and fits against the bottom plane of the recessed area. The predetermined gap exists between the conductive wire and the patterned conductive seed layer.

3. The method according to claim 1, characterized in that, The conductive filament serves as the cathode, and the conductive connection layer grows from the conductive filament into the conductive seed layer until the conductive connection layer is connected to the patterned conductive seed layer.

4. The method according to claim 1, characterized in that, The patterned conductive seed layer serves as the cathode, and the conductive connection layer grows from the patterned conductive seed layer toward the conductive filament until the conductive connection layer is connected to the conductive filament.

5. The method according to claim 2, characterized in that, The conductive connection layer covers the surface of the conductive wire near the battery body.

6. The method according to claim 3, characterized in that, The orthographic projection of the conductive connection layer on the battery body lies within the orthographic projection of the patterned conductive seed layer on the battery body.

7. The method according to any one of claims 1 to 5, characterized in that, The spacing of the predetermined gap is equal to the thickness of the conductive connection layer.

8. The method according to any one of claims 1 to 5, characterized in that, The thickness of the conductive connection layer is 20 to 200 micrometers, and / or the material of the conductive connection layer includes at least one of copper and silver.

9. A solar cell, characterized in that, It is prepared by the method described in any one of claims 1 to 8.

10. A photovoltaic device, characterized in that, Includes the solar cell as described in claim 9.

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