Electrode preparation method of solar cell and solar cell

Abstract

The invention provides an electrode preparation method of a solar cell and the solar cell, and the method comprises the steps: providing a to-be-metalized solar cell which is provided with an electrode region and a non-electrode region which are adjacent to each other; forming a seed layer on the electrode region and the non-electrode region; forming a first mask on the seed layer; a second mask is formed on the first mask, the second mask covers the electrode area and part of the non-electrode area, and the width of the second mask ranges from 10 micrometers to 20 micrometers; performing graphical processing on the first mask and the second mask to form an opening for exposing the seed layer in the electrode region; electroplating an electrode on the seed layer exposed from the opening, wherein the height of the electrode is equal to or smaller than the depth of the opening; and removing the first mask and the second mask. The cost of the mask can be reduced by forming the mask with the uneven thickness, in addition, the height of the electrode is equal to or smaller than the depth of the opening, in the electroplating process, the appearance of the electrode is limited by the side wall of the opening all the time, and an electrode structure with the large upper portion and the small lower portion cannot be formed, so that the shielding of the incident light by the electrode can be reduced.

Description

Technical Field

[0001] The present application mainly relates to the field of photovoltaic technology, and in particular to a method for preparing an electrode of a solar cell and a solar cell. Background Art

[0002] The electrode preparation method of solar cells includes screen printing process and electroplating process. The shading area of ​​the screen-printed electrode is relatively high, and due to the limitation of the screen printing process itself, it is difficult to further reduce the shading area of ​​the electrode. In addition, the silver particles in the electrode prepared by screen printing are not in sufficient contact with the silicon substrate, resulting in a high contact resistance. In the current electroplating process, electroplating is performed after preparing the mask and exposing and developing, and the width of the formed electrode is still relatively large. Therefore, how to reduce the electrode width is one of the research directions in this field. Summary of the invention

[0003] The technical problem to be solved by the present application is to provide a method for preparing an electrode of a solar cell and a solar cell. The method for preparing an electrode of a solar cell and the solar cell can reduce the width of the electrode, which can reduce the shielding of the incident light by the electrode.

[0004] To solve the above technical problems, the present application provides a method for preparing an electrode of a solar cell, comprising: providing a solar cell to be metallized, the solar cell to be metallized having adjacent electrode areas and non-electrode areas; forming a seed layer on the electrode area and the non-electrode area; forming a first mask on the seed layer; forming a second mask on the first mask, the second mask covering the electrode area and part of the non-electrode area, the width of the second mask being 10 μm to 20 μm; patterning the first mask and the second mask to form an opening exposing the seed layer located in the electrode area; electroplating an electrode on the seed layer exposed by the opening, the height of the electrode being equal to or less than the depth of the opening; and removing the first mask and the second mask.

[0005] In one embodiment of the present application, the area of ​​the non-electrode region covered by the second mask is smaller than the area of ​​the electrode region covered by the second mask.

[0006] In one embodiment of the present application, the method for forming the first mask and the second mask includes: forming a first mask on the seed layer by a printing or spraying process, and the first mask is a wet film mask; forming a second mask on the first mask by a printing or spraying process, and the second mask is a wet film mask.

[0007] In one embodiment of the present application, a method for patterning the first mask and the second mask includes: drying the first mask and the second mask; and exposing and developing the first mask and the second mask.

[0008] In one embodiment of the present application, the rate and duration of electroplating the electrode are controlled according to the depth of the opening so that the height of the electrode is equal to or less than the depth of the opening.

[0009] In an embodiment of the present application, the thickness of the first mask is 5 μm to 15 μm, and the thickness of the second mask is 10 μm to 20 μm.

[0010] In one embodiment of the present application, the aspect ratio of the electrode is 1 to 1.5:1.

[0011] In an embodiment of the present application, materials of the seed layer and the electrode include copper, copper-nickel alloy or copper-tin alloy.

[0012] On the other hand, the present application further provides a solar cell, wherein the electrode of the solar cell is prepared by the method for preparing the electrode of the solar cell as described above.

[0013] In an embodiment of the present application, the width of the electrode is 10 μm to 20 μm, and the height of the electrode is 10 μm to 20 μm.

[0014] In one embodiment of the present application, the solar cell further includes a transparent conductive layer and an anti-reflection layer, which are sequentially stacked on at least one side of the solar cell, the thickness of the transparent conductive layer is 5nm to 20nm, and the thickness of the anti-reflection layer is 30nm to 60nm.

[0015] Compared with the prior art, this application has the following advantages:

[0016] (1) Compared with forming a mask with uniform thickness, the present application can reduce the cost of the mask by forming a mask with non-uniform thickness (the mask at the electrode area is thicker);

[0017] (2) The height of the electrode of the present application is equal to or less than the depth of the opening. During the electroplating process, the shape of the electrode is always restricted by the side wall of the opening, and an electrode structure with a larger top and a smaller bottom will not be formed. In this way, the electrode can reduce the shielding of incident light. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the present application. They are included and constitute a part of the present application. The accompanying drawings illustrate embodiments of the present application and together with the present specification serve to explain the principles of the present application. In the accompanying drawings:

[0019] Figure 1 It is a schematic flow chart of a method for preparing an electrode of a solar cell in one embodiment of the present application;

[0020] Figures 2 to 9is a schematic cross-sectional view of a solar cell in different steps in an embodiment of the present application;

[0021] Fig.10 It is a cross-sectional schematic diagram of a solar cell in one embodiment of the present application.

[0022] Reference numerals: solar cell to be metallized 210 , electrode region 211 , non-electrode region 212 , seed layer 220 , first mask 230 , second mask 240 , opening 250 , electrode 260 , transparent conductive layer 270 , anti-reflection layer 280 . DETAILED DESCRIPTION

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0024] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0025] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so that once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0026] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0027] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0028] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0029] Flowcharts are used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed accurately in order. On the contrary, various steps may be processed in reverse order or simultaneously. At the same time, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0030] Next, the method for preparing the electrode of the solar cell and the solar cell of the present application are described through examples.

[0031] refer to Figure 1 As shown, Figure 1 The method for preparing the electrode of the solar cell in the embodiment comprises the following steps:

[0032] S110: providing a solar cell to be metallized, wherein the solar cell to be metallized has adjacent electrode regions and non-electrode regions;

[0033] S120: forming a seed layer on the electrode region and the non-electrode region;

[0034] S130: forming a first mask on the seed layer;

[0035] S140: forming a second mask on the first mask, the second mask covering the electrode area and part of the non-electrode area, and the width of the second mask is 10 μm to 20 μm;

[0036] S150: performing patterning on the first mask and the second mask to form an opening exposing the seed layer located in the electrode region;

[0037] S160: electroplating an electrode on the seed layer exposed by the opening, wherein the height of the electrode is equal to or less than the depth of the opening;

[0038] S170: removing the first mask and the second mask.

[0039] Next, steps S110 to S170 are described in detail.

[0040] refer to Figure 2 As described above, in step S110, a solar cell 210 to be metallized is provided. The solar cell 210 to be metallized refers to a solar cell that has the basic film layers necessary for operation but has not yet formed electrodes. The solar cell 210 to be metallized has adjacent electrode areas 211 and non-electrode areas 212. Figure 2 and Fig. 9 As shown, the electrode region 211 refers to the region where the electrode 260 is located in the solar cell 210 to be metallized, and the width of the electrode region 211 is substantially equal to the width of the electrode 260. The non-electrode region 212 refers to the region where no electrode is provided in the solar cell 210 to be metallized.

[0041] The solar cell 210 to be metallized may have a velvet structure to reduce reflection of incident light. The solar cell 210 to be metallized may be an intrinsic thin film heterojunction cell (Heterojunction with Intrinsic Thin-film, HJT) or a tunnel oxide passivated contact cell (Tunnel Oxide Passivated Contact, TOPCon).

[0042] refer to Figure 2 and Figure 3 As shown, in step S120, a seed layer 220 is formed on the electrode area 211 and the non-electrode area 212, and the seed layer 220 covers the electrode area 211 and the non-electrode area 212. The seed layer 220 may include copper, copper-nickel alloy or copper-tin alloy, and the seed layer 220 may be formed using a physical vapor deposition process (e.g., a magnetron sputtering process in physical vapor deposition), an electron beam evaporation process or a thermal evaporation process. The thickness of the seed layer 220 may be any value within the range of 5nm to 20nm, for example, the thickness of the seed layer 220 is 5nm, 10nm, 15nm or 20nm.

[0043] refer to Figure 3 As shown, in S130, a first mask 230 is formed on the seed layer 220, and the first mask 230 covers the seed layer 220. Figure 3 and Figure 4 As shown, a second mask 240 is formed on the first mask 230, and the second mask 240 covers the electrode area 211 and part of the non-electrode area 212. In detail, the projection of the second mask 240 in the vertical direction covers the electrode area 211 and part of the non-electrode area 212, and the width of the second mask 240 should be as small as possible under the premise of meeting the requirements of the subsequent electroplating electrode, so as to reduce the cost of the second mask 240. For example, in one embodiment, the area of ​​the non-electrode area 212 covered by the second mask 240 is smaller than the area of ​​the electrode area 211 covered by the second mask 240; for another example, in another embodiment, the width of the second mask 240 is any value in the range of 10μm to 20μm, such as a width of 10μm, 15μm or 20μm.

[0044] In one embodiment, the method for forming the first mask 230 and the second mask 240 includes: forming the first mask 230 on the seed layer 220 by a printing or spraying process, wherein the first mask 230 is a wet film mask; forming the second mask 240 on the first mask 230 by a printing or spraying process, wherein the second mask 240 is a wet film mask. The wet film mask has the advantages of low cost and high efficiency. It is understood that the method for forming the first mask 230 and the second mask 240 in the present application is not limited to the above embodiment.

[0045] refer to Figure 4 and Figure 5As shown, in step S150, the first mask 230 and the second mask 240 are patterned to form an opening 250, and the opening 250 exposes the seed layer located in the electrode region 211. Specifically, the opening 250 is located directly above the electrode region 211, and the opening 250 exposes the seed layer located in the electrode region 211. The width of the opening 250 is substantially equal to the width of the electrode region 211. It should be noted that, due to the limitations of the patterning process itself and other reasons, the width of the opening 250 may be slightly smaller than or slightly larger than the width of the electrode region 211, and this situation is also within the protection scope of the present application.

[0046] In one embodiment, a method for patterning the first mask 230 and the second mask 240 includes: first, drying the first mask 230 and the second mask 240, both of which are wet film masks; then, exposing and developing the first mask 230 and the second mask 240, and forming an opening 250 after the exposure and development.

[0047] Considering the first mask 230 and the second mask 240 as a whole, compared with forming a mask with uniform thickness, the present application can reduce the cost of the mask by forming a mask with uneven thickness (the mask at the electrode region 211 is thicker).

[0048] refer to Figure 5 and Figure 6 As shown, in step S160, an electrode 260 is electroplated on the seed layer exposed by the opening 250, and the electrode 260 is located in the opening 250, and the height of the electrode 260 is equal to or less than the depth of the opening 250. The depth of the opening 250 is equal to the sum of the thickness of the first mask 230 and the second mask 240. In one embodiment, the thickness of the first mask 230 is any value in the range of 5μm to 15μm, such as 5μm, 10μm or 15μm, and the thickness of the second mask 240 is 10μm to 20μm, such as 10μm, 15μm or 20μm.

[0049] The height of the electrode 260 being equal to or less than the depth of the opening 250 has the following effects. During the electroplating process, the shape of the electrode 260 is always limited by the sidewalls of the opening 250, so that the width of the electrode 260 is equal to the width of the opening 250. If the height of the electrode 260 is greater than the width of the opening 250, the width of the portion of the electrode outside the opening 250 is not limited during the electroplating process, which will cause its width to be greater than the width of the opening 250, ultimately forming an electrode structure that is larger at the top and smaller at the bottom. Compared with the electrode structure that is larger at the top and smaller at the bottom, the width of the electrode 260 of the present application is consistent from top to bottom, so that the electrode 260 can reduce the shielding of the incident light.

[0050] In one embodiment, the rate and duration of the electroplating electrode can be controlled according to the depth of the opening 250, so that the height of the electrode 260 is equal to or less than the depth of the opening 250. The depth of the opening 250 of the present application is relatively deep (equal to the sum of the thickness of the first mask 230 and the second mask 240). Compared with the opening with a shallower depth, the opening 250 increases the process parameter window for regulating the height of the electrode 260, so that it is convenient to control the height of the electrode 260 by controlling the rate and duration of the electroplating electrode, thereby ensuring that the height of the electrode 260 does not exceed the depth of the opening 250.

[0051] In one embodiment, the height of the electrode 260 is equal to or greater than the width of the electrode 260, and the aspect ratio of the electrode 260 is any value in the range of 1 to 1.5:1, for example, the aspect ratio is 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1. The height of the electrode 260 is equal to or greater than the width of the electrode 260, which can reduce the resistance of the electrode 260 while reducing the shielding of incident light.

[0052] In one embodiment, the electrode 260 includes copper, copper-nickel alloy or copper-tin alloy. Compared with precious metals such as silver, using the above materials to make the electrode 260 can reduce the cost of the electrode 260.

[0053] refer to Figure 6 and Figure 7 As shown, in step S170, the first mask 230 and the second mask 240 are removed. In some embodiments, after step S170, a portion of the seed layer 220 located on the non-electrode region 212 is removed to form a Figure 8 Seed layer 220 is shown. Fig. 9 As shown, the seed layer 220 located on the non-electrode area 212 may also be completely removed, and only the seed layer 220 located on the electrode area 211 is retained.

[0054] On the other hand, the present application also provides a solar cell, wherein the electrode in the solar cell is prepared by the electrode preparation method as described above. Figures 7 to 9 As shown, in one embodiment, the width of the electrode 260 is any value in the range of 10μm to 20μm, for example, the width is 10μm, 15μm or 20μm, and the height of the electrode 260 is any value in the range of 10μm to 20μm, for example, the height is 10μm, 15μm or 20μm.

[0055] refer to Fig.10As shown, in one embodiment, the solar cell includes a transparent conductive layer 270 and an anti-reflection layer 280, which are sequentially stacked on at least one side of the solar cell, the seed layer 220 is located on the transparent conductive layer 270, the anti-reflection layer 280 covers the transparent conductive layer 270, and the upper end of the electrode 260 is exposed from the anti-reflection layer 280. The thickness of the transparent conductive layer 270 is any value within the range of 5nm to 20nm, for example, the thickness is 5nm, 10nm, 15nm or 20nm. The thickness of the transparent conductive layer 270 is equal to or less than 20nm, which can reduce the parasitic absorption caused by the transparent conductive layer 270 and reduce the cost of the transparent conductive layer 270.

[0056] The thickness of the anti-reflection layer 280 is any value within the range of 30 nm to 60 nm, for example, the thickness is 30 nm, 40 nm, 50 nm or 60 nm.

[0057] In one embodiment, the transparent conductive layer 270 includes one or more of tin oxide, zinc oxide, titanium oxide, indium tin oxide, doped zinc oxide, and doped titanium oxide. The transparent conductive layer 270 can improve the lateral conductivity of the solar cell and make it easier to collect photogenerated carriers.

[0058] In one embodiment, the anti-reflection layer 280 includes one or more of silicon oxide, aluminum oxide, tantalum oxide, niobium oxide, silicon nitride, and silicon oxynitride. The anti-reflection layer 280 can reduce the reflection of incident light by the solar cell and block external water vapor.

[0059] The basic concepts have been described above. Obviously, for those skilled in the art, the above application disclosure is only an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0060] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0061] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more application embodiments, in the above description of the embodiments of this application, multiple features are sometimes merged into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0062] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0063] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions may be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the essential spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A method for preparing an electrode for a solar cell, characterized in that: include: Providing a solar cell to be metallized, wherein the solar cell to be metallized has adjacent electrode regions and non-electrode regions; forming a seed layer on the electrode region and the non-electrode region; forming a first mask on the seed layer; forming a second mask on the first mask, wherein the second mask covers the electrode area and part of the non-electrode area, and the width of the second mask is 10 μm to 20 μm; Performing patterning on the first mask and the second mask to form an opening exposing the seed layer located in the electrode region; Electroplating an electrode on the seed layer exposed by the opening, wherein the height of the electrode is equal to or less than the depth of the opening; as well as The first mask and the second mask are removed.

2. The method for preparing an electrode for a solar cell according to claim 1, wherein: The area of ​​the non-electrode region covered by the second mask is smaller than the area of ​​the electrode region covered by the second mask.

3. The method for preparing an electrode for a solar cell according to claim 1, wherein: The method of forming the first mask and the second mask includes: Forming a first mask on the seed layer by a printing or spraying process, wherein the first mask is a wet film mask; A second mask is formed on the first mask by a printing or spraying process, and the second mask is a wet film mask.

4. The method for preparing an electrode for a solar cell according to claim 3, characterized in that: The method for patterning the first mask and the second mask includes: drying the first mask and the second mask; The first mask and the second mask are subjected to exposure and development processing.

5. The method for preparing an electrode for a solar cell according to claim 1, wherein: The rate and duration of electroplating the electrode are controlled according to the depth of the opening so that the height of the electrode is equal to or less than the depth of the opening.

6. The method for preparing an electrode for a solar cell according to claim 1, wherein: The thickness of the first mask is 5 μm to 15 μm, and the thickness of the second mask is 10 μm to 20 μm.

7. The method for preparing an electrode for a solar cell according to claim 1, wherein: The aspect ratio of the electrode is 1 to 1.5:

1.

8. The method for preparing an electrode for a solar cell according to claim 1, wherein: The seed layer and the electrode are made of copper, copper-nickel alloy or copper-tin alloy.

9. A solar cell, characterized in that: The electrode of the solar cell is prepared by the method for preparing an electrode of a solar cell according to any one of claims 1 to 8.

10. The solar cell according to claim 9, characterized in that The width of the electrode is 10 μm to 20 μm, and the height of the electrode is 10 μm to 20 μm.

11. The solar cell according to claim 9, wherein: It also includes a transparent conductive layer and an anti-reflection layer, which are sequentially stacked on at least one side of the solar cell. The thickness of the transparent conductive layer is 5nm to 20nm, and the thickness of the anti-reflection layer is 30nm to 60nm.

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