Preparation method of solar cell and solar cell

Abstract

The invention provides a preparation method of a solar cell and the solar cell. The preparation method of the solar cell comprises the following steps: providing a solar cell intermediate; a mold is placed on the solar cell intermediate, the mold is provided with channels distributed at intervals, each channel is provided with an opening allowing the electroplating liquid to flow through, and the mold is insulated; electroplating an electroplating layer in the channel; and after electroplating is finished, the mold is removed for repeated use. According to the technical scheme of preparing the metal electrode by means of the mold, the steps of photoresist coating, exposure, development and the like are not needed, the process steps of electroplating the metal electrode are greatly simplified, in addition, the mold can be repeatedly used, and the cost of preparing the metal electrode is reduced.

Description

Technical Field

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

[0002] In the preparation process of solar cells, screen printing is often used to prepare metal electrodes. The width of the metal electrodes prepared by screen printing is between 20 and 30 μm, and it is difficult to further reduce the width of the metal electrodes. Electroplating technology can reduce the width of the metal electrode, but electroplating technology requires the use of a mask, and the process of preparing the mask is complicated and costly. In addition, the cross-section of the metal electrode prepared by electroplating technology is formed into a semicircular or semi-elliptical shape, which causes the light irradiated on the metal electrode to be reflected into the air. Therefore, how to reduce the manufacturing cost of metal electrodes and prepare metal electrodes that can reflect light to the active area is one of the important 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 a solar cell and a solar cell. The method for preparing a solar cell and the solar cell have the advantages of simple process steps and low cost, and the metal electrode can reflect incident light to the active area.

[0004] To solve the above technical problems, the present application provides a method for preparing a solar cell, comprising: providing a solar cell intermediate; placing a mold on the solar cell intermediate, the mold having spaced-apart channels, the channels having openings for allowing electroplating solution to flow, and the mold being insulated; electroplating a plating layer in the channels; and after the electroplating is completed, removing the mold for reuse.

[0005] In one embodiment of the present application, before placing the mold on the solar cell intermediate, the method further includes: performing a groove process on the solar cell intermediate to expose a portion of the doping layer, wherein the electroplating layer is in contact with the doping layer.

[0006] In one embodiment of the present application, the cross-section of the channel is triangular.

[0007] In one embodiment of the present application, the step of electroplating the electroplating layer in the channel includes: placing the solar cell intermediate with the mold placed thereon into a first electroplating solution containing copper ions; and electroplating the copper-containing electroplating layer in the channel.

[0008] In one embodiment of the present application, the step of electroplating the electroplating layer in the channel includes: placing the solar cell intermediate with the mold placed thereon into the first electroplating solution; electroplating the copper-containing electroplating layer in the channel; transferring the solar cell intermediate from the first electroplating solution to a second electroplating solution, wherein the second electroplating solution contains silver ions;

[0009] The silver-containing electroplating layer is electroplated to cover at least a portion of the copper-containing electroplating layer.

[0010] In one embodiment of the present application, the mold further has a connecting portion connecting adjacent channels, and the channel protrudes from the connecting portion, wherein the connecting portion and the channel are made of a plate-like material.

[0011] In one embodiment of the present application, the opening is located at the top of the channel, and / or the opening is located at the side wall of the channel.

[0012] In one embodiment of the present application, the angle between the two side walls of the channel is equal to or less than 120°.

[0013] In one embodiment of the present application, the material of the mold includes acrylic and / or polypropylene.

[0014] On the other hand, the present application further proposes a solar cell, comprising: a plurality of metal electrodes arranged at intervals, wherein a method for preparing the metal electrodes comprises the step of electroplating using a mold.

[0015] In an embodiment of the present application, the metal electrode includes a first layer and a second layer, the second layer covers at least a portion of the first layer, wherein the first layer includes metal copper, and the second layer includes metal silver.

[0016] In one embodiment of the present application, the cross-section of the metal electrode is in the shape of a triangle.

[0017] In one embodiment of the present application, the angle between the two side surfaces of the metal electrode is equal to or less than 120°.

[0018] Compared with the prior art, this application has the following advantages:

[0019] (1) The technical solution of preparing metal electrodes with the help of molds in the present application does not require steps such as coating photoresist, exposure and development, which greatly simplifies the process steps of electroplating metal electrodes.

[0020] (2) The mold of the present application can be reused, which reduces the manufacturing cost of the metal electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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:

[0022] Figure 1 is a schematic flow chart of a method for preparing a solar cell in one embodiment of the present application;

[0023] Figures 2 to 5 is a schematic cross-sectional view of a solar cell during the process of preparing the solar cell in one embodiment of the present application;

[0024] Figure 6 is a cross-sectional schematic diagram of a solar cell in one embodiment of the present application;

[0025] Figure 7 Schematic diagram of the cross section of a metal electrode in one embodiment of the present application.

[0026] Reference numerals

[0027] Solar cell intermediate body 110 Second tunneling layer 117 Electroplating layer 140

[0028] Silicon substrate 111 Mold 120 Solar cell 210

[0029] First doping layer 112 Channel 121 Body 211

[0030] Anti-reflection layer 113 Opening 122 Metal electrode 212

[0031] Second doping layer 114 Connecting portion 123 Side surface 212a

[0032] Passivation layer 115 Sidewall 124 First layer 212b

[0033] First tunneling layer 116 Groove 130 Second layer 212c DETAILED DESCRIPTION

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] Next, the preparation method of the solar cell and the solar cell of the present application are described through examples.

[0042] refer to Figure 1 As shown, in one embodiment, the method for preparing a solar cell includes the following steps S110 to S140.

[0043] Step S110: providing a solar cell intermediate;

[0044] Step S120: placing a mold on the solar cell intermediate, the mold having channels distributed at intervals, the channels having openings for the flow of the electroplating solution, and the mold being insulated;

[0045] Step S140: After the electroplating is completed, the mold is removed for reuse.

[0046] Next, steps S110 to S140 are described in detail.

[0047] refer to Figure 2 As shown, in step S110, a solar cell intermediate 110 is provided, and the solar cell intermediate 110 has a first doping layer 112 and an anti-reflection layer 113 stacked on the front side of a silicon substrate 111, and a second doping layer 114 and a passivation layer 115 stacked on the back side of the silicon substrate 111. The first doping layer 112 can be an N-type or P-type doped polysilicon layer, and the second doping layer 114 can be an N-type or P-type doped polysilicon layer, and the doping type of the first doping layer 112 is opposite to the doping type of the second doping layer 114. It can be understood that film layers can be added or reduced on the basis of the above-mentioned film layers according to needs, for example, a first tunneling layer 116 and / or a second tunneling layer 117 can be added. The solar cell intermediate 110 refers to a solar cell that has not been metallized (i.e., a metal electrode has not been formed).

[0048] refer to Figure 2 and Figure 3 As shown, in step S120, the mold 120 is placed on the solar cell intermediate 110. Figure 3 The dotted lines in the figure illustrate the schematic diagram of the structure before the mold 120 is placed on the solar cell intermediate 110. The mold 120 has channels 121 distributed at intervals, and the channels 121 have openings 122 for the flow of the electroplating solution. Figure 3 The middle opening 122 is located at the top of the channel 121 . In other embodiments, the opening 122 may be disposed on the side wall 124 of the channel 121 . The opening 122 may also be disposed on both the side wall 124 and the top of the channel 121 .

[0049] The mold 120 is insulated, and the material of the mold 120 may include acrylic and / or polypropylene. Figure 3 In the embodiment, the mold 120 has a connection portion 123 connecting adjacent channels 121, the channels 121 protrude from the connection portion 123, and the connection portion 123 and the channels 121 are made of a plate-like material. Specifically, the mold 120 is processed from an insulating plate, the plate at the connection portion 123 maintains the shape of the insulating plate before processing, and the insulating plate at the channel 121 protrudes after processing, thereby forming the channel 121.

[0050] refer to Figure 3As shown, in one embodiment, the angle α between the two side walls 124 is equal to or less than 120°, for example, the angle α between the two side walls 124 is 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110° or 120°. The angle α being equal to or less than 120° is conducive to the subsequently prepared metal electrode reflecting the incident light to the active area of ​​the solar cell.

[0051] exist Figure 3 In the embodiment, the cross section of the channel 121 is substantially triangular, and it can be understood that the triangle is incomplete due to the presence of the opening 122. In some other embodiments, the cross section of the channel 121 can also be other shapes, such as a trapezoid, and the angle between the two side walls of the trapezoid is equal to or less than 120°.

[0052] refer to Figure 3 and Figure 4 As shown, in step S130, the electroplating layer 140 is electroplated in the channel 121. During the electroplating of the electroplating layer 140, the channel 121 has a limiting effect on the shape of the electroplating layer, so the cross-sectional shape of the electroplating layer in the channel 121 is the same as the cross-sectional shape of the channel 121.

[0053] because Figure 2 The solar cell intermediate 110 is covered with an anti-reflection layer 113, and before placing the mold 120 on the solar cell intermediate 11, the process also includes: slotting the solar cell intermediate 110, wherein the slots 130 formed by the slotting process expose part of the first doping layer 112, and the electroplating layer 140 contacts the first doping layer 112 and forms an electrical connection. For heterojunction cells, the slotting process step can be omitted, and the metal electrode can be directly prepared on the transparent conductive layer.

[0054] In the above embodiments, the preparation of the metal electrode on one side of the solar intermediate is taken as an example for description. It should be understood that the metal electrode can also be prepared on the other side of the solar intermediate.

[0055] Here is an example to illustrate the process of slotting and electroplating. The example includes the following steps:

[0056] Step 1: Laser groove the solar cell intermediate, where the groove is located in the metal grid electrode area.

[0057] Step 2: Remove oil stains from the surface of the solar intermediate. Specifically, first use ultrasonic cleaning; then rinse with deionized water; finally use alkali solution cleaning, put the grooved side of the solar intermediate into the alkali solution to remove the thermal damage layer at the groove; take the solar intermediate out of the alkali solution and rinse with deionized water. The alkali solution includes 5% to 10% (weight percentage) sodium hydroxide or potassium hydroxide, and the rest is deionized water. The immersion time in the alkali solution is 20s to 40s.

[0058] Step 3: Remove the oxide film at the laser grooved area. Specifically, soak the grooved side of the solar intermediate in acid solution, take out the solar cell from the acid solution, rinse it with deionized water, and dry it.

[0059] Step 4: Place the molds on the front and back of the solar cell intermediate and fix the molds with clamps.

[0060] Step 5: Place the solar intermediate from step 4 in the electroplating bath and start electroplating.

[0061] Step 6: Remove the mold.

[0062] Step 7: Rinse the solar intermediate from step 6 with deionized water.

[0063] Step 8: Drying the solar intermediate in step 7.

[0064] In one embodiment, the step of electroplating the electroplating layer in the channel includes: placing the solar cell intermediate with the mold placed in the first electroplating solution, the first electroplating solution contains copper ions; electroplating the copper-containing electroplating layer in the channel, and the electroplated electroplating layer in this embodiment includes metallic copper. In another embodiment, the step of electroplating the electroplating layer in the channel includes: placing the solar cell intermediate with the mold placed in the first electroplating solution; electroplating the copper-containing electroplating layer in the channel; transferring the solar cell intermediate from the first electroplating solution to the second electroplating solution, the second electroplating solution contains silver ions; electroplating the silver-containing electroplating layer covering at least part of the copper-containing electroplating layer, in this embodiment, a copper-containing electroplating layer is first electroplated, and then a silver-containing electroplating layer is electroplated on the copper-containing electroplating layer. The electroplating layer finally formed includes the copper-containing electroplating layer and the silver-containing electroplating layer located on the outer layer. The reflectivity of silver is higher than that of copper. By utilizing the advantage of the high reflectivity of silver, more light can be reflected to the active area.

[0065] refer to Figure 4 and Figure 5As shown, in step S140, after the electroplating is completed, the mold 120 is removed for reuse. Different from the technical solution of forming a mask by an exposure and development process, on the one hand, the technical solution of preparing a metal electrode by means of a mold in the present application does not require the steps of coating photoresist, exposure and development, etc., which greatly simplifies the process steps of electroplating metal electrodes; on the other hand, the mask formed by the exposure and development process cannot be reused, while the mold 120 of the present application can be reused, which reduces the cost of preparing metal electrodes.

[0066] On the other hand, the present application also proposes a solar cell, Figure 5 As shown, in one embodiment, the solar cell 210 includes a main body 211 and a plurality of metal electrodes 212 arranged at intervals on the main body 211. The preparation method of the metal electrode 212 includes the step of electroplating using the mold described above. The mold can be reused. For the description of the mold, please refer to the description of the mold described above, which will not be expanded here. The solar cell can be prepared using the preparation method described above. For the description, please refer to the above, which will not be expanded here.

[0067] refer to Figure 7 As shown, in one embodiment, the cross-section of the metal electrode 212 is in the shape of a triangle. It is understood that due to reasons such as the manufacturing process, the shape of the cross-section may not be a triangle in the strict sense, and this situation is also within the scope of protection of the present application. The angle between the two side surfaces 212a of the metal electrode 212 is equal to or less than 120°, for example, the angle is 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110° or 120°. For electrodes with other cross-sectional shapes, the angle between the two side surfaces may also be equal to or less than 120°. An angle equal to or less than 120° helps to reflect light to the active area.

[0068] Continue to refer Figure 7 As shown, in one embodiment, the metal electrode 212 includes a first layer 212b and a second layer 212c, the second layer 212c covers the first layer 212b, the first layer 212b includes metal copper, and the second layer 212c includes metal silver. Since silver has a higher reflectivity, the silver located in the outer layer is beneficial to improving the reflection of light by the metal electrode 212. Figure 7 In the embodiment, the second layer 212c covers all sides of the first layer 212b. In some other embodiments, the second layer 212c may cover part of the sides of the first layer 212b.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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 a solar cell, characterized in that: include: Providing solar cell intermediates; Placing a mold on the solar cell intermediate, wherein the mold has channels distributed at intervals, the channels have openings for the plating solution to flow, and the mold is insulated; electroplating a plating layer in the channel; as well as After electroplating is complete, the mold is removed for reuse.

2. The method for preparing a solar cell according to claim 1, characterized in that: Before placing the mold on the solar cell intermediate, the method further includes: performing a groove process on the solar cell intermediate to expose a portion of the doping layer, wherein the electroplating layer contacts the doping layer.

3. The method for preparing a solar cell according to claim 1, wherein: The cross section of the channel is triangular.

4. The method for preparing a solar cell according to claim 1, wherein: The step of electroplating a plating layer in the channel comprises: placing the solar cell intermediate with the mold placed thereon into a first electroplating solution, wherein the first electroplating solution contains copper ions; A copper-containing plating layer is electroplated in the via.

5. The method for preparing a solar cell according to claim 4, characterized in that: The step of electroplating a plating layer in the channel comprises: placing the solar cell intermediate having the mold placed thereon into the first electroplating solution; electroplating a copper-containing electroplating layer in the channel; Transferring the solar cell intermediate from the first plating solution to a second plating solution, wherein the second plating solution contains silver ions; The silver-containing electroplating layer is electroplated to cover at least a portion of the copper-containing electroplating layer.

6. The method for preparing a solar cell according to claim 1, wherein: The mold further comprises a connecting portion for connecting adjacent channels, wherein the channels protrude from the connecting portion, wherein the connecting portion and the channels are made of a plate-shaped material.

7. The method for preparing a solar cell according to claim 1, wherein: The opening is located at the top of the channel, and / or the opening is located at the side wall of the channel.

8. The method for preparing a solar cell according to claim 1, wherein: The angle between the two side walls of the channel is equal to or less than 120°.

9. The method for preparing a solar cell according to claim 1, wherein: The material of the mold includes acrylic and / or polypropylene.

10. A solar cell, characterized in that: include: A plurality of metal electrodes are arranged at intervals, and the preparation method of the metal electrodes comprises the step of electroplating using a mold.

11. The solar cell according to claim 10, wherein: The metal electrode includes a first layer and a second layer, wherein the second layer covers at least a portion of the first layer, wherein the first layer includes metal copper, and the second layer includes metal silver.

12. The solar cell according to claim 10, wherein: The cross section of the metal electrode is in the shape of a triangle.

13. The solar cell according to claim 10, wherein: The angle between the two side surfaces of the metal electrode is equal to or less than 120°.

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