Solar cell and method of manufacturing the same

Abstract

This application provides a solar cell and its fabrication method. The solar cell includes: a substrate layer having opposing front and back surfaces; a front electrode located on the front surface, comprising multiple parallel sub-grids and multiple parallel main grids, wherein any main grid intersects any sub-grid, and any sub-grid is disconnected between at least two adjacent main grids, forming a front gap; and a back electrode located on the back surface, comprising at least two back electric fields and multiple back electrodes, wherein the back electric fields are connected to the back electrodes, any two back electrodes are not connected to each other, and each back electrode corresponds one-to-one with a main grid. Adjacent back electric fields are not connected, forming a back gap, and the projection of the back gap onto the front surface covers the front gap between two corresponding adjacent main grids. This solar cell solves the problem of low conversion efficiency in existing solar cells.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and more specifically, to a solar cell and a method for its fabrication. Background Technology

[0002] Solar cells are an important way for people to generate electricity in the future. Printed electrodes are a key step in the manufacturing of solar cells. Generally, screen printing is used to form electrode structures on the front and back of the silicon wafer. The grid pattern on the front side and the shape of the back surface determine the size of the effective light-receiving area of ​​the solar cell and the current transmission, thus determining the cell's conversion efficiency.

[0003] Generally, in solar cell printing patterns, the main grids are connected through sub-grids, and the printed aluminum back field on the back electrode is interconnected, with each main grid connected in parallel for output. Because the main grids are connected through sub-grids, the potentials of each main grid are slightly different, resulting in internal current in the solar cell printing pattern. This causes losses in open-circuit voltage and short-circuit current, leading to low conversion efficiency of the solar cell.

[0004] The information disclosed above in the background section is only intended to enhance the understanding of the background art of the art described herein. Therefore, the background art may contain certain information that does not constitute prior art known to those skilled in the art in this country. Summary of the Invention

[0005] The main objective of this application is to provide a solar cell and a method for its fabrication, in order to solve the problem of low conversion efficiency in existing solar cells.

[0006] According to one aspect of the present invention, a solar cell is provided, comprising: a substrate layer having opposing front and back surfaces; a front electrode located on the front surface, the front electrode comprising a plurality of parallel sub-grids and a plurality of parallel main grids, wherein any one of the main grids intersects any one of the sub-grids, and any one of the sub-grids is disconnected between at least two adjacent main grids to form a front gap; and a back electrode located on the back surface, the back electrode comprising at least two back electric fields and a plurality of back electrodes, wherein the back electric fields are connected to the back electrodes, any two back electrodes are not connected to each other, and the back electrodes correspond one-to-one with the main grids, and adjacent two back electric fields are not connected to form a back gap, wherein the projection of the back gap on the front surface covers the front gap between corresponding adjacent two main grids.

[0007] Optionally, any one of the sub-gates is disconnected between any two adjacent main gates.

[0008] Optionally, any one of the main gates and any one of the sub-gates are perpendicular.

[0009] Optionally, the front gap has a length of 1mm to 5mm in the length direction of the sub-gate, and the back gap has a length of 1mm to 5mm in the length direction of the sub-gate.

[0010] Optionally, the main grid can be a straight structure, a hollow structure, or a segmented structure. In the hollow structure, the main grid includes multiple hollow points. In the segmented structure, the main grid includes multiple grid lines with a gap between adjacent grid lines.

[0011] According to another aspect of the present invention, a method for fabricating a solar cell is provided, the method comprising: forming an antireflection passivation film on the back surface of a substrate; opening a window in the antireflection passivation film to expose a portion of the back surface of the substrate, wherein the remaining antireflection passivation film forms a plurality of first reserved portions and second reserved portions, the plurality of first reserved portions being parallel to each other, and the second reserved portions being located between two adjacent first reserved portions; forming a back electrode on the surface of the first reserved portions corresponding to each other; forming a back electric field at the window location on the back surface; forming a plurality of parallel sub-gates and a plurality of parallel main gates on the front surface of the substrate, such that any one of the main gates intersects with any one of the sub-gates, the main gates corresponding to the back electrodes, and any one of the sub-gates being disconnected between at least two adjacent main gates to form a front gap, wherein the projection of the second reserved portion on the front surface covers the front gap between two corresponding adjacent main gates, and the front surface is opposite to the back surface.

[0012] Optionally, opening a window in the antireflection passivation film includes: laser etching the antireflection passivation film, wherein the ratio of the pulse duration to the interruption time of the laser is 1.0 to 2.0.

[0013] Optionally, there is a second reserved part between any two adjacent first reserved parts.

[0014] Optionally, any one of the main gates and any one of the sub-gates are perpendicular.

[0015] Optionally, the second reserved portion has a length of 1mm to 5mm in the length direction of the sub-gate, and the front gap has a length of 1mm to 5mm in the length direction of the sub-gate.

[0016] In this embodiment of the invention, the solar cell includes a semiconductor substrate, a front electrode, and a back electrode. The substrate layer has opposing front and back surfaces. The front electrode is located on the front surface and includes multiple parallel sub-gates and multiple parallel main gates. Any one of the main gates intersects with any one of the sub-gates, and any one of the sub-gates is disconnected between at least two adjacent main gates, forming a front gap. The back electrode is located on the back surface and includes at least two back electric fields and multiple back electrodes. The back electric fields are connected to the back electrodes, and any two back electrodes are not connected to each other. The back electrodes correspond one-to-one with the main gates, and adjacent back electric fields are not connected, forming a back gap. The projection of the back gap onto the front surface covers the front gap between the corresponding two adjacent main gates. Each of the aforementioned sub-grids of the solar cell is disconnected between at least one set of two adjacent main grids, and the two adjacent back electric fields are not connected to form a back gap, that is, the corresponding back electrodes are not connected, so that at least two independent small cells are formed on the semiconductor substrate. The main grids of the two independent small cells are not connected, and the back electrodes are not connected, which reduces the internal current of the printed pattern of the solar cell, reduces the loss of open circuit voltage and short circuit current, thereby improving the conversion efficiency of the solar cell and solving the problem of low conversion efficiency of solar cells in the prior art. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 A schematic diagram of the front electrode according to an embodiment of this application is shown;

[0019] Figure 2 A schematic diagram of a back electrode according to an embodiment of this application is shown;

[0020] Figure 3 A flowchart illustrating a method for fabricating a solar cell according to an embodiment of this application is shown;

[0021] Figure 4 A schematic diagram of the back surface of the substrate after laser windowing according to an embodiment of this application is shown;

[0022] Figure 5 An embodiment according to this application is shown. Figure 4 A magnified view of the circled area.

[0023] The above figures include the following reference numerals:

[0024] 10. Substrate; 20. Front electrode; 21. Main gate; 22. Sub gate; 30. Back electrode; 31. Back electric field; 32. Back electrode; 40. Front gap; 50. Back gap; 60. First reserved portion; 70. Second reserved portion. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0029] As mentioned in the background section, existing solar cells suffer from low conversion efficiency. To address this issue, in a typical embodiment of this application, a solar cell and its fabrication method are provided.

[0030] According to embodiments of this application, a solar cell is provided, such as... Figure 1 and Figure 2 As shown, the aforementioned solar cell includes:

[0031] The base layer 10 has a front surface and a back surface with opposite sides;

[0032] The front electrode 20 is located on the front surface. The front electrode 20 includes multiple parallel sub-gates 22 and multiple parallel main gates 21. Any one of the main gates 21 intersects with any one of the sub-gates 22. Any one of the sub-gates 22 is broken between at least two adjacent main gates 21 to form a front gap 40.

[0033] The back electrode 30 is located on the back surface. The back electrode 30 includes at least two back electric fields 31 and a plurality of back electrodes 32. The back electric fields 31 are connected to the back electrodes 32. Any two back electrodes 32 are not connected to each other. The back electrodes 32 correspond one-to-one with the main gate 21. Adjacent back electric fields 31 are not connected to form a back gap 50. The projection of the back gap 50 on the front surface covers the front gap 40 between the corresponding two adjacent main gates 21.

[0034] The aforementioned solar cell includes a semiconductor substrate, a front electrode, and a back electrode. The substrate layer has opposing front and back surfaces. The front electrode is located on the front surface and includes multiple parallel sub-gates and multiple parallel main gates. Any one of the main gates intersects with any one of the sub-gates, and any one of the sub-gates is disconnected between at least two adjacent main gates, forming a front gap. The back electrode is located on the back surface and includes at least two back electric fields and multiple back electrodes. The back electric fields are connected to the back electrodes, and any two back electrodes are not connected to each other. The back electrodes correspond one-to-one with the main gates, and adjacent back electric fields are not connected, forming a back gap. The projection of the back gap onto the front surface covers the front gap between the corresponding two adjacent main gates. Each of the aforementioned sub-grids of the solar cell is disconnected between at least one set of two adjacent main grids, and the two adjacent back electric fields are not connected to form a back gap, that is, the corresponding back electrodes are not connected, so that at least two independent small cells are formed on the semiconductor substrate. The main grids of the two independent small cells are not connected, and the back electrodes are not connected, which reduces the internal current of the printed pattern of the solar cell, reduces the loss of open circuit voltage and short circuit current, thereby improving the conversion efficiency of the solar cell and solving the problem of low conversion efficiency of solar cells in the prior art.

[0035] It should be noted that the above-mentioned substrate layer is a material layer that can generate photovoltaic effect, and preferably, the above-mentioned substrate layer is a monocrystalline silicon layer.

[0036] In one embodiment of this application, such as Figure 1As shown, each of the aforementioned sub-grids 22 is disconnected between any two adjacent primary grids 21. Specifically, the disconnection between any of the aforementioned sub-grids and any two adjacent primary grids ensures that each primary grid corresponds to an independent small cell, further reducing the internal current of the solar cell printed pattern, further reducing open-circuit voltage and short-circuit current losses, and thus further improving the conversion efficiency of the solar cell.

[0037] In one embodiment of this application, such as Figure 1 As shown, each of the aforementioned main grids 21 and each of the aforementioned sub-grids 22 are perpendicular. Specifically, the perpendicularity between each of the aforementioned main grids and each of the aforementioned sub-grids allows for the formation of a sufficient number of sub-grids on the substrate, resulting in a compact positive electrode pattern structure and further improving the conversion efficiency of the solar cell.

[0038] In one embodiment of this application, the length of the front gap in the sub-gate length direction is 1mm to 5mm, and the length of the back gap in the sub-gate length direction is 1mm to 5mm. Specifically, setting the lengths of the front gap and the back gap in the sub-gate length direction within the above range can reduce the blank area of ​​the substrate layer and further improve the conversion efficiency of the solar cell. In addition, the lengths of different front gaps in the sub-gate length direction can be the same or different, so that the breaks of each sub-gate are aligned or serrated.

[0039] In one embodiment of this application, the main grid is a straight structure, a hollow structure, or a segmented structure. In the hollow structure, the main grid includes multiple hollow points. In the segmented structure, the main grid includes multiple grid lines with a gap between adjacent grid lines. Specifically, in the straight structure, the main grid forms a continuous straight line without hollow points. In the hollow structure, the hollow structure has multiple hollow points, which can save the slurry used to form the main grid and reduce production costs. In the segmented structure, the main grid includes multiple grid lines to further improve conversion efficiency and reduce production costs. Of course, the main grid can also be a complete grid line, and those skilled in the art can choose a suitable main grid structure as needed.

[0040] According to embodiments of this application, a method for preparing a solar cell is also provided, such as... Figure 3 As shown, the method includes the following steps:

[0041] Step S101: An anti-reflection passivation film is formed on the back surface of the substrate layer;

[0042] Step S102: A window is made in the antireflection passivation film, exposing a portion of the back surface of the substrate layer. The remaining antireflection passivation film forms a plurality of first reserved portions 60 and second reserved portions 70. The plurality of first reserved portions 60 are parallel to each other, and the second reserved portions 70 are located between two adjacent first reserved portions 60. Figure 4 As shown;

[0043] Step S103: Form back electrodes one by one on the surface of the first reserved portion;

[0044] Step S104: A back electric field is formed at the window position on the back surface.

[0045] Step S105: Multiple parallel sub-gates and multiple parallel main gates are formed on the front surface of the substrate layer, such that any one of the main gates intersects with any one of the sub-gates, and the main gates correspond one-to-one with the back electrode. Any one of the sub-gates is disconnected between at least two adjacent main gates to form a front gap. The projection of the second reserved portion on the front surface covers the front gap between the corresponding two adjacent main gates. The front surface is opposite to the back surface.

[0046] In the above-described method for fabricating a solar cell, firstly, an anti-reflection passivation film is formed on the back surface of a substrate layer; then, windows are made in the anti-reflection passivation film to expose a portion of the back surface of the substrate layer, and the remaining anti-reflection passivation film forms multiple first and second reserved portions, the multiple first reserved portions being parallel to each other, and the second reserved portions being located between two adjacent first reserved portions; subsequently, back electrodes are formed one-to-one on the surfaces of the first reserved portions; then, a back electric field is formed at the window positions on the back surface; finally, multiple parallel sub-gates and multiple parallel main gates are formed on the front surface of the substrate layer, such that any one of the main gates intersects with any one of the sub-gates, the main gates correspond one-to-one with the back electrodes, any one of the sub-gates is disconnected between at least two adjacent main gates to form a front gap, the projection of the second reserved portion on the front surface covers the front gap between the corresponding two adjacent main gates, and the front surface is opposite to the back surface. This fabrication method forms a main grid and a sub-grid, such that any one of the sub-grids is disconnected between at least one set of two adjacent main grids. The second reserved portion ensures that two adjacent back electric fields are not connected, forming a gap, that is, the corresponding back electrodes are not connected. This results in at least two independent small cells being formed on the semiconductor substrate. The main grids of the two independent small cells are not connected, and the back electrodes are not connected. This reduces the internal current of the printed pattern of the solar cell, lowers the losses of open-circuit voltage and short-circuit current, thereby improving the conversion efficiency of the solar cell and solving the problem of low conversion efficiency of solar cells in the prior art.

[0047] In one embodiment of this application, creating a window in the antireflection passivation film includes: laser etching of the antireflection passivation film, wherein the ratio of the pulse duration to the interruption time of the laser is 1.0 to 2.0. Specifically, Figure 5 for Figure 4 A magnified view of the circled area, as shown below. Figure 5 As shown, laser etching section A and non-laser etching section B are shown. From the lengths of A and B, it can be seen that the ratio of the pulse duration to the interruption time of the laser is approximately 1:1.

[0048] In one embodiment of this application, each of the aforementioned sub-gates is disconnected between any two adjacent primary gates. Specifically, since each of the aforementioned sub-gates is disconnected between any two adjacent primary gates, one primary gate corresponds to an independent small cell, further reducing the internal current of the solar cell printed pattern, further reducing open-circuit voltage and short-circuit current losses, thereby further improving the conversion efficiency of the solar cell.

[0049] In one embodiment of this application, any one of the aforementioned main grids is perpendicular to any one of the aforementioned sub-grids. Specifically, the perpendicularity of any one of the aforementioned main grids to any one of the aforementioned sub-grids allows for the formation of a sufficient number of sub-grids on the substrate layer, resulting in a compact positive electrode pattern structure and further improving the conversion efficiency of the solar cell.

[0050] In one embodiment of this application, the length of the front gap in the sub-gate length direction is 1mm to 5mm, and the length of the back gap in the sub-gate length direction is 1mm to 5mm. Specifically, setting the lengths of the front gap and the back gap in the sub-gate length direction within the above range can reduce the blank area of ​​the substrate layer and further improve the conversion efficiency of the solar cell. In addition, the lengths of different front gaps in the sub-gate length direction can be the same or different, so that the breaks of each sub-gate are aligned or serrated.

[0051] In order to enable those skilled in the art to better understand the technical solution of this application, the technical solution of this application will be described below in conjunction with specific embodiments.

[0052] Example 1

[0053] The front electrode of the solar cell in this embodiment includes 5 parallel main grids and 116 parallel sub-grids. Each of the main grids and sub-grids is perpendicular to each other. Each sub-grid is disconnected between any two adjacent main grids, forming a front gap. The back laser window of the solar cell has 170 lines, and the ratio of pulse duration to interruption time is 0.5mm:0.5mm. The back electrode includes 5 back electric fields and 5 back electrodes. The back electric fields are connected to the back electrodes. Any two back electrodes are not connected to each other, and each back electrode corresponds to one of the main grids. Any two adjacent back electric fields are not connected, forming a back gap. The projection of the back gap onto the front surface covers the front gap between the corresponding two adjacent main grids.

[0054] Comparative Example 1

[0055] The only difference between the solar cell of Comparative Example 1 and the solar cell of Example 1 is that:

[0056] None of the aforementioned sub-grids are disconnected. The back electrode of the solar cell includes one back electric field and five back electrodes, and the five back electric fields are all connected to the aforementioned back electrodes.

[0057] The solar cells of Example 1 and Comparative Example 1 were tested, and the test results are shown in Table 1.

[0058] Table 1

[0059]

[0060] As shown in Table 1, the open-circuit voltage and short-circuit current of Example 1 are higher than those of Comparative Example 1, but the series resistance and fill factor are slightly worse, and the battery conversion efficiency can be improved by more than 0.07%.

[0061] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0062] 1) The solar cell of this application includes a semiconductor substrate, a front electrode, and a back electrode. The substrate layer has opposing front and back surfaces. The front electrode is located on the front surface and includes multiple parallel sub-gates and multiple parallel main gates. Any one of the main gates intersects with any one of the sub-gates, and any one of the sub-gates is disconnected between at least two adjacent main gates to form a front gap. The back electrode is located on the back surface and includes at least two back electric fields and multiple back electrodes. The back electric fields are connected to the back electrodes. Any two back electrodes are not connected to each other, and the back electrodes correspond one-to-one with the main gates. Adjacent back electric fields are not connected to each other to form a back gap. The projection of the back gap onto the front surface covers the front gap between the corresponding two adjacent main gates. Each of the aforementioned sub-grids of the solar cell is disconnected between at least one set of two adjacent main grids, and the two adjacent back electric fields are not connected to form a back gap, that is, the corresponding back electrodes are not connected, so that at least two independent small cells are formed on the semiconductor substrate. The main grids of the two independent small cells are not connected, and the back electrodes are not connected, which reduces the internal current of the printed pattern of the solar cell, reduces the loss of open circuit voltage and short circuit current, thereby improving the conversion efficiency of the solar cell and solving the problem of low conversion efficiency of solar cells in the prior art.

[0063] 2) In the method for fabricating a solar cell according to this application, firstly, an anti-reflection passivation film is formed on the back surface of a substrate layer; then, a portion of the anti-reflection passivation film is removed, exposing a portion of the back surface of the substrate layer, and the remaining anti-reflection passivation film forms a plurality of first reserved portions and second reserved portions, the plurality of first reserved portions being parallel to each other, and the second reserved portions being located between two adjacent first reserved portions; then, back electrodes are formed one-to-one on the surfaces of the first reserved portions; then, a back electric field is formed at the opening positions on the back surface; finally, a plurality of parallel sub-grids and a plurality of parallel main grids are formed on the front surface of the substrate layer, such that any one of the main grids intersects with any one of the sub-grids, the main grids correspond one-to-one with the back electrodes, any one of the sub-grids is disconnected between at least two adjacent main grids, forming a front gap, the projection of the second reserved portion on the front surface covers the front gap between the corresponding two adjacent main grids, and the front surface is opposite to the back surface. This fabrication method forms a main grid and a sub-grid, such that any one of the sub-grids is disconnected between at least one set of two adjacent main grids. The second reserved portion ensures that two adjacent back electric fields are not connected, forming a gap, that is, the corresponding back electrodes are not connected. This results in at least two independent small cells being formed on the semiconductor substrate. The main grids of the two independent small cells are not connected, and the back electrodes are not connected. This reduces the internal current of the printed pattern of the solar cell, lowers the losses of open-circuit voltage and short-circuit current, thereby improving the conversion efficiency of the solar cell and solving the problem of low conversion efficiency of solar cells in the prior art.

[0064] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A solar cell, characterized by, include: The base layer has a front surface and a back surface; A front electrode is located on the front surface. The front electrode includes multiple parallel sub-gates and multiple parallel main gates. Any main gate intersects with any sub-gate. Any sub-gate is broken between at least two adjacent main gates. The breaks between the multiple sub-gates are serrated, forming the serrated front gap. A back electrode is located on the back surface. The back electrode includes at least two back electric fields and multiple back electrodes. The back electric fields are connected to the back electrodes. Any two back electrodes are not connected to each other. The back electrodes correspond one-to-one with the main gate. Adjacent back electric fields are not connected to form a back gap. The projection of the back gap on the front surface covers the front gap between two adjacent main gates. Each of the sub-gates is disconnected between any two adjacent main gates; The front gap has a length of 1mm to 5mm in the direction of the sub-gate length, and the back gap has a length of 1mm to 5mm in the direction of the sub-gate length. The main grid can be a straight structure, a hollow structure, or a segmented structure. In the hollow structure, the main grid includes multiple hollow points. In the segmented structure, the main grid includes multiple grid lines with a gap between adjacent grid lines.

2. The battery of claim 1, wherein, Each of the main gates and each of the sub-gates are perpendicular.

3. A method for preparing a solar cell, characterized in that, The method includes: An anti-reflection passivation film is formed on the back surface of the substrate layer; A window is made in the antireflection passivation film, exposing part of the back surface of the substrate layer. The remaining antireflection passivation film forms a plurality of first reserved portions and second reserved portions. The plurality of first reserved portions are parallel to each other, and the second reserved portions are located between two adjacent first reserved portions. Back electrodes are formed one-to-one on the surface of the first reserved portion; A back electric field is formed at the window location on the back surface; Multiple parallel sub-gates and multiple parallel main gates are formed on the front surface of the substrate layer, such that any one of the main gates intersects with any one of the sub-gates. Each main gate corresponds to a back electrode. Each sub-gate is broken between at least two adjacent main gates. The breaks between the multiple sub-gates are serrated, forming a serrated front gap. The projection of the second reserved portion on the front surface covers the front gap between two adjacent main gates. The front surface is opposite to the back surface. The second reserved portion has a length of 1mm to 5mm in the length direction of the sub-gate, and the front gap has a length of 1mm to 5mm in the length direction of the sub-gate.

4. The method according to claim 3, characterized in that, Creating a window in the antireflective passivation film includes: The antireflection passivation film is etched using laser, and the ratio of the laser pulse duration to the interruption time is 1.0 to 2.

0.

5. The method according to claim 3, characterized in that, There is a second reserved part between any two adjacent first reserved parts.

6. The method according to claim 3, characterized in that, Each of the main gates and each of the sub-gates are perpendicular.

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