Solar cell, solar cell module, and electric device

Abstract

The application relates to the technical field of solar cells, in particular to a solar cell, a solar cell module and an electric device, the solar cell comprising a metal electrode, the metal electrode comprising a plurality of electrically connected patterned grid line units, the patterned grid line unit comprising: a first polygonal border grid line; a first bridge grid line located inside the first polygonal border grid line and connected between the geometric center of the first polygonal border grid line and the vertex of the first polygonal border grid line; and an internal filling grid line located inside the first polygonal border grid line and electrically connected to at least one of the first bridge grid line and the first polygonal border grid line. In the solar cell, the carrier transport path is short, the current collection efficiency is high, the resistance loss is small, and the cost is relatively low.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, specifically to solar cells, solar cell modules, and electrical devices. Background Technology

[0002] Currently, conductive grid lines in solar cells are generally prepared using screen-printed silver paste, which has relatively poor long-term stability and makes it difficult to achieve fine grid line patterning smaller than 20μm. Wider grid lines result in greater shading loss, lower photoelectric conversion efficiency, and higher cost. Furthermore, the grid line design in related technologies is primarily orthogonal main grid and fine grid, but ohmic losses occur during long-distance current transmission, reducing cell performance. Therefore, solar cell technologies still require improvement. Utility Model Content

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a solar cell, solar cell module, and electrical device that feature a short carrier transport path, high current collection efficiency, low resistance loss, or low cost.

[0004] In a first aspect, this application provides a solar cell. According to an embodiment of this application, the solar cell includes a metal electrode comprising a plurality of electrically connected patterned grid line units. Each patterned grid line unit includes: a first polygonal border grid line; a first bridging grid line located inside the first polygonal border grid line and connected between the geometric center and a vertex of the first polygonal border grid line; and an internal filling grid line located inside the first polygonal border grid line and electrically connected to at least one of the first bridging grid line and the first polygonal border grid line. The patterned grid line units allow for non-orthogonal angles between the grid lines, shortening the carrier transport path, improving current collection efficiency, reducing resistance loss, and thus enhancing the photoelectric conversion efficiency of the solar cell. Furthermore, this patterned design eliminates the need to distinguish between main grids and fine grids, resulting in narrower grid line widths, thereby saving raw materials and reducing costs.

[0005] According to embodiments of this application, the included angle between any two electrically connected gate lines is not equal to 90°.

[0006] According to an embodiment of this application, two adjacent patterned grid line units share a side of the first polygonal border grid line.

[0007] According to an embodiment of this application, at least one vertex of the first polygonal border grid line is recessed inward.

[0008] According to an embodiment of this application, the shape of the first polygonal border grid line is hexagonal, and the three spaced vertices of the hexagon are recessed inward.

[0009] According to an embodiment of this application, in adjacent patterned grid cells, the inwardly recessed vertices are arranged close to each other to form a solder joint space.

[0010] According to an embodiment of this application, the internal filling grid line includes: a second polygonal border grid line, the shape of which is similar to that of the first polygonal border grid line and their geometric centers coincide; and a second bridging grid line, which is located inside the second polygonal border grid line and connects the geometric center of the second polygonal border grid line to the vertex of the second polygonal border grid line, and the second bridging grid line and the first bridging grid line are alternately arranged around the geometric center of the second polygonal border grid line.

[0011] According to an embodiment of this application, at least a portion of the gate lines in the patterned gate line unit include a plurality of parallel sub-gate lines.

[0012] According to an embodiment of this application, a connecting sub-grid line is provided between two adjacent sub-grid lines, and the connecting sub-grid line is electrically connected to the two adjacent sub-grid lines.

[0013] According to an embodiment of this application, the width of the gate line in the patterned gate line unit is 10μm to 15μm; the aspect ratio of the gate line in the patterned gate line unit is not less than 50%.

[0014] In a second aspect, this application provides a solar cell module. According to embodiments of this application, the solar cell module includes the solar cell described above. This solar cell module has low cost and high conversion efficiency.

[0015] A third aspect of this application provides an electrical device. According to embodiments of this application, it includes the aforementioned solar cell or the aforementioned solar cell module. This electrical device possesses all the features and advantages described above, which will not be repeated here. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a patterned grid line unit according to an embodiment of this application.

[0017] Figure 2 This is a schematic diagram of the structure of a metal electrode according to an embodiment of this application.

[0018] Figure 3 This is a partial structural schematic diagram of a metal electrode according to an embodiment of this application.

[0019] Figure 4 This is a schematic diagram of the structure of a metal electrode according to another embodiment of this application.

[0020] Figure 5 This is a schematic flowchart of a method for preparing a metal electrode according to an embodiment of this application.

[0021] Figure 6 This is a schematic diagram of the structure of a heterojunction solar cell according to an embodiment of this application.

[0022] Figure 7 This is a schematic flowchart of a method for preparing a heterojunction solar cell according to an embodiment of this application. Detailed Implementation

[0023] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] In a first aspect, this application provides a solar cell. According to an embodiment of this application, referring to... Figure 1 and Figure 2 The solar cell includes a metal electrode 100, which includes a plurality of electrically connected patterned grid units 10. The patterned grid unit 10 includes: a first polygonal border grid 11; a first bridging grid 12 located inside the first polygonal border grid 11 and connected between the geometric center A of the first polygonal border grid 11 and a vertex C of the first polygonal border grid 11; and an internal filling grid 13 located inside the first polygonal border grid 11 and electrically connected to at least one of the first bridging grid 12 and the first polygonal border grid 11. In the aforementioned patterned grid unit 10, the first polygonal frame grid lines allow the grid lines to form non-orthogonal angles. Combined with the design of the first bridging grid lines and the internally filled grid lines, the distance from any point on the cell surface to the grid lines can be shortened, reducing the probability of carriers being lost due to recombination before reaching the grid lines. This achieves more uniform and efficient current collection, thereby shortening the carrier transport path, improving current collection efficiency, reducing resistance loss, and ultimately improving the photoelectric conversion efficiency of the solar cell. Moreover, this patterned design eliminates the need to distinguish between the main grid and the fine grid; the current path is grid line-solder strip. Compared to the grid structure where the current path is fine grid-main grid-solder strip, the current in the patterned grid unit of this application does not need to travel a long distance, reducing resistance loss in the grid network. Furthermore, the grid lines can all be formed with a narrower width, thus saving raw materials and reducing costs.

[0025] Specifically, the patterned grid unit is polygonal, containing various line structures as internal filler grids to assist in current collection. This design, while ensuring aesthetic appeal, also offers multiple advantages in practical applications, such as excellent structural stability, resistance to deformation, effective stress distribution, and improved overall load-bearing capacity. The dense distribution of internal grids, with non-orthogonal angles between them, effectively assists in carrier collection and current transmission, shortening the carrier transmission path, improving current collection efficiency, and reducing resistance losses.

[0026] In this article, a polygon refers to a closed figure composed of five or more line segments, that is, a polygon with at least five sides. It can be understood that a metal electrode can simultaneously include multiple first polygonal border lines of different shapes, such as pentagonal, hexagonal, heptagonal, and octagonal border lines. As an example, multiple first polygonal border lines can completely cover the surface on which the metal electrode is located. Figure 2 The illustration shows a scenario where a hexagonal border grid completely covers the surface where the metal electrodes are located. It can be understood that the surface where the metal electrodes are located can also be completely covered by polygonal border grids of different shapes.

[0027] According to embodiments of this application, the shape of the first polygonal border grid line 11 can be a regular polygon, an irregular polygon, etc., which can be selected according to actual needs. As an example, the shape of the first polygonal border grid line 11 can be a regular hexagon.

[0028] According to embodiments of this application, the electrical connection method between multiple patterned gate line units 10 is not particularly limited; they can be directly electrically connected (e.g., through vertex connection, edge connection, etc.) or indirectly electrically connected (e.g., through separate connecting lines). As an example, see... Figure 3 Two adjacent patterned grid units 10 share a side 110 of the first polygonal border grid line. This connection method further reduces shading losses and electrode ohmic losses in the solar cell, thereby further improving conversion efficiency.

[0029] According to embodiments of this application, the included angle between two gate lines in an arbitrarily electrically connected patterned gate line unit is not equal to 90°, or in other words, the included angle between two gate lines in an arbitrarily electrically connected patterned gate line unit is an acute or obtuse angle. As an example, Figure 1 The diagram shows obtuse angles α, acute angles β, and γ between different gate lines. This allows for a more effective shortening of the carrier transport path, improved current collection efficiency, and reduced resistance losses.

[0030] According to the embodiments of this application, referring to Figure 1At least one vertex C of the first polygonal border grid line 11 is recessed inward. Specifically, the polygon with the recessed vertex can be a concave polygon, thereby the recessed vertex can form a solder joint position, which facilitates welding with the solder strip connecting the solar cell to form a solar cell module.

[0031] According to the embodiments of this application, referring to Figure 3 In adjacent patterned grid units 10, the inwardly recessed vertices C are positioned close to each other to form a solder joint space 102. This solder joint space can thus define solder joint locations, facilitating welding with the solder strips connecting the solar cells to form a solar cell module.

[0032] According to the embodiments of this application, referring to Figure 1 The first polygonal border grid 11 is hexagonal in shape, with three spaced vertices C recessed inwards, and the other three vertices B being non-recessed. This results in a honeycomb-like structure for the metal electrodes, which shortens the carrier transport path, improves current collection efficiency, and reduces resistance loss.

[0033] According to embodiments of this application, the shape of the internally filled gate lines is not particularly limited, as long as they are filled inside the first polygonal border gate lines 11, which helps to shorten the carrier transport path, improve current collection efficiency, and reduce resistance loss. In some embodiments, refer to Figure 1 The internal filling grid 13 includes: a second polygonal border grid 131, the shape of which is similar to that of the first polygonal border grid 11, and their geometric centers coincide; and a second bridging grid 132, located inside the second polygonal border grid 131, connecting the geometric center of the second polygonal border grid 131 to its vertices, with the second bridging grid 132 and the first bridging grid 12 alternately arranged around the geometric center of the second polygonal border grid 131. This results in a shorter carrier transport path, higher current collection efficiency, and lower resistance loss.

[0034] According to the embodiments of this application, referring to Figure 4 At least a portion of the grid lines in the patterned grid line unit 10 include multiple parallel sub-grid lines 120. This allows for narrower sub-grid line widths, smaller shading area, less shading loss, and higher photoelectric conversion efficiency of the battery while maintaining conductivity.

[0035] It should be noted that the sub-grid lines in each grid line can include completely parallel sub-grid lines. The lengths of the sub-grid lines can be the same or different, and can be flexibly adjusted as needed.

[0036] According to an embodiment of this application, a connecting sub-gate line 121 is provided between two adjacent sub-gate lines 120, and the connecting sub-gate line 121 is electrically connected to the two adjacent sub-gate lines 120. It is understood that the number and placement of the connecting sub-gate lines 121 are not particularly required; they can be selected according to actual needs to shorten the carrier transport path. This further shortens the carrier transport path, improves current collection efficiency, and greatly reduces resistance loss.

[0037] In some embodiments, the width of the gate lines in the patterned gate line unit is 10μm to 15μm (specifically, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, etc.); the aspect ratio of the gate lines in the patterned gate line unit is not less than 50%, specifically 50%, 60%, 70%, 80%, 90%, 100%, etc. This saves raw materials and reduces costs; and it eliminates the need to distinguish between the main gate and the fine gate, further shortening the carrier transport path, improving current collection efficiency, and greatly reducing resistance losses. As an example, the width and height of the gate lines in the patterned gate line unit are the same. Therefore, there is no need to distinguish between the main gate and the fine gate, and narrower gate lines can be used, thus saving raw materials and reducing costs.

[0038] It can be understood that when the grid lines in the patterned grid line unit are composed of a single grid line, it means that the width of the single grid line is 10μm to 15μm and the aspect ratio of the single grid line is not less than 50%; while when the grid lines in the patterned grid line unit include multiple sub-grid lines, the width of the sub-grid lines can be 10μm to 15μm and the aspect ratio of the sub-grid lines can be not less than 50%.

[0039] According to embodiments of this application, the material of the metal electrode is not particularly limited, as long as it has good conductivity. In some embodiments, the metal electrode is made of copper. Therefore, it can be prepared by electroplating. The copper grid structure prepared by electroplating copper technology is dense, has stronger conductivity, narrower grid width, smaller shading area, less shading loss, and higher photoelectric conversion efficiency of the solar cell.

[0040] Specifically, the cost of the copper grid wire is significantly lower than that of the silver grid wire. Although the resistance of copper is slightly higher than that of silver, the resistance of the grid wire after curing is higher than that of the copper grid wire because the low-temperature silver paste contains a binder phase, organic solvents and various auxiliary additives. Therefore, the electroplated copper grid wire reduces the grid wire body resistance and the electrode ohmic loss, thereby increasing the fill factor of the solar cell. This can improve the efficiency of the solar cell, reduce the amount of raw materials used, and lower the production cost.

[0041] Furthermore, the linewidth of the copper grid lines can be narrower, typically reaching 10μm to 15μm, with an aspect ratio of no less than 50%, and potentially approaching 1; while the linewidth of screen-printed grid lines is typically 30μm, with an aspect ratio of around 0.35. The battery grid lines of this application have narrower widths, better uniformity in grid morphology, less incident light obstruction area, and a superior aspect ratio, thus increasing the short-circuit current density of the solar cell and significantly improving its conversion efficiency.

[0042] In some embodiments, reference is made to Figure 5 The manufacturing process of electroplated copper grid lines can include the following steps:

[0043] (1) A seed layer 202 is deposited on the transparent electrode layer 201 to improve the adhesion between the gate line and the transparent electrode layer and to improve the contact resistance between the interface. The specific deposition method can be PVD (physical vapor deposition), and the seed layer can be silver, copper, nickel, etc. In addition to single-element seed layers, co-deposited metal elements can also be used as seed layers.

[0044] (2) Forming a patterned mask: Photosensitive ink or photoresist 203 is printed on the surface of the seed layer. After drying, ultraviolet light is used to irradiate the substrate coated with photosensitive ink or photoresist through the mask, causing the photosensitive ink or photoresist to undergo a chemical reaction. Using different patterned mask materials, openings 204 of the corresponding pattern of the patterned grid line unit can be formed on the photosensitive ink or photoresist.

[0045] (3) A copper layer 205 is deposited on a patterned photosensitive ink or photoresist by an electrochemical method. Specifically, during electrodeposition, the substrate is used as the cathode and is immersed in a bath containing acidic copper sulfate. After an electric current is applied, copper metal is deposited onto the substrate.

[0046] (4) Post-processing: After electrodeposition, the substrate surface film is removed, and the seed layer not covered by the copper grid line is removed by etching solution to expose the transparent electrode layer and form metal electrode 206.

[0047] The method of preparing copper electrodes by electroplating in this application results in finer and denser grid lines. The grid line patterning design improves current collection efficiency, reduces resistance loss, light shading loss and electrode ohmic loss, and improves battery conversion efficiency.

[0048] According to embodiments of this application, the specific type of solar cell is not particularly limited, including but not limited to heterojunction solar cells (HJT), back contact cells (BC), passivated contact cells (TOPCon), etc. Therefore, the metal electrode of this application has broad applicability.

[0049] In some embodiments, a heterojunction solar cell is used as an example, with reference to Figure 6The solar cell comprises: a crystalline silicon substrate 1, a passivation layer 2, an n-doped silicon layer 3, a transparent conductive layer 4, a copper electrode 5, and a p-doped silicon layer 6. Compared with screen-printed silver grid lines, the copper grid lines prepared using electroplating technology are finer and denser, resulting in reduced shading loss and electrode ohmic loss, and improved conversion efficiency.

[0050] In some embodiments, reference is made to Figure 7 The fabrication method of a heterojunction solar cell may include the following steps:

[0051] (1) Provide a crystalline silicon substrate. Specifically, a texturing and cleaning machine can be used to clean and texturize the silicon wafer to remove the getter layer on the surface of the silicon wafer, and a pyramidal textured surface can be prepared on the surface to obtain light trapping ability, thereby providing an n-type single crystal silicon substrate;

[0052] (2) A passivation layer is deposited on a crystalline silicon substrate. Specifically, an intrinsic amorphous silicon passivation layer can be deposited on the back side of the crystalline silicon substrate using a PECVD device, and then deposited on the front side of the crystalline silicon substrate after flipping it over.

[0053] (3) Deposit a microcrystalline doped layer on the passivation layer. Specifically, an n-type doped layer can be deposited on the front side, and a p-type doped layer can be deposited on the back side after flipping. The deposition process can be PECVD (plasma-enhanced chemical vapor deposition).

[0054] (4) Deposit a transparent conductive layer on the microcrystalline doped layer. Specifically, a transparent conductive layer can be deposited on the doped layer on both the front and back sides using a PVD device to help collect current and reduce reflection.

[0055] (5) Electroplating copper grid lines onto the transparent conductive layer. Specifically, copper electrodes can be fabricated on the outermost layer using copper electroplating equipment to form a loop with the external circuit and conduct current.

[0056] According to the embodiments of the application, the main structure of the solar cell remains basically unchanged, except that the metal electrode has been patterned and the preparation method has been improved. The use of composite patterned metal electrodes can significantly reduce the production cost of solar cells, reduce shading loss, obtain higher short-circuit current, and improve conversion efficiency.

[0057] In a second aspect, this application provides a solar cell module. According to embodiments of this application, the solar cell module includes the solar cell described above. This solar cell module has low cost and high conversion efficiency.

[0058] A third aspect of this application provides an electrical device. According to embodiments of this application, it includes the aforementioned solar cell or the aforementioned solar cell module. This electrical device possesses all the features and advantages described above, which will not be repeated here.

[0059] In the description of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0060] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0061] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is 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.

[0062] 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 solar cell, characterized in that, The device includes a metal electrode, the metal electrode comprising a plurality of electrically connected patterned gate line units, the patterned gate line units comprising: First polygonal border grid lines; The first bridging grid line is located inside the first polygonal border grid line and connects the geometric center of the first polygonal border grid line to the vertex of the first polygonal border grid line. An internal filler grid line is located inside the first polygonal border grid line and is electrically connected to at least one of the first bridging grid line and the first polygonal border grid line.

2. The solar cell according to claim 1, characterized in that, The included angle between any two gate lines that are electrically connected is not equal to 90°.

3. The solar cell according to claim 1, characterized in that, Two adjacent patterned grid units share a side of the first polygonal border grid.

4. The solar cell according to claim 1, characterized in that, At least one vertex of the first polygonal border grid line is recessed inward.

5. The solar cell according to claim 1, characterized in that, The first polygonal border grid is hexagonal in shape, with the three spaced vertices of the hexagon being recessed inward.

6. The solar cell according to claim 4 or 5, characterized in that, In adjacent patterned grid cells, the inwardly recessed vertices are positioned close to each other to form solder joint spaces.

7. The solar cell according to claim 1, characterized in that, The internal filler grid lines include: The second polygonal border grid line has a shape similar to that of the first polygonal border grid line, and their geometric centers coincide. The second bridging grid line is located inside the second polygonal border grid line, connecting the geometric center of the second polygonal border grid line and the vertex of the second polygonal border grid line, and the second bridging grid line and the first bridging grid line are alternately arranged around the geometric center of the second polygonal border grid line.

8. The solar cell according to any one of claims 1 to 7, characterized in that, At least some of the grid lines in the patterned grid line unit include multiple parallel sub-grid lines.

9. The solar cell according to claim 8, characterized in that, A connecting subgrid line is provided between two adjacent subgrid lines, and the connecting subgrid line is electrically connected to the two adjacent subgrid lines.

10. The solar cell according to claim 1, characterized in that, The width of the grid lines in the patterned grid line unit is 10μm to 15μm; the aspect ratio of the grid lines in the patterned grid line unit is not less than 50%.

11. A solar cell module, characterized in that, The solar cell includes any one of claims 1 to 10.

12. An electrical appliance, characterized in that, Includes the solar cell according to any one of claims 1 to 10 or the solar cell module according to claim 11.

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