Preparation method of solar cell

Abstract

The embodiment of the invention provides a preparation method of a solar cell, and relates to the field of photovoltaic technology. The preparation method comprises the steps of firstly forming a plurality of filling structures on the surface of a battery substrate, then forming a mask layer on the surface of the battery substrate, then removing the plurality of filling structures to form a plurality of cavities in the mask layer, forming a plurality of grid lines in the plurality of cavities, and electrically connecting the plurality of grid lines with the battery substrate. Through the method, the filling structure can be utilized to form the mask layer with the specific morphology, and then the grid line is formed, namely, the morphology of the grid line can be adjusted by controlling the morphology of the filling structure. As the width of the second part, far away from the cell substrate, of the filling structure in the second direction is smaller than the width of the first part, close to the cell substrate, of the filling structure in the second direction, the formed grid line also has the characteristic of narrow upper part and wide lower part, the efficient secondary reflection and utilization of incident light can be realized, the short-circuit current and the conversion efficiency can be improved, and the conversion efficiency can be improved. And the single-watt cost is further reduced.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and particularly to a method for manufacturing a solar cell. Background Art

[0002] Currently, the grid line material of a solar cell usually includes photovoltaic silver paste. In order to reduce the silver consumption, low-cost conductive materials such as silver-coated copper paste, copper paste, electroplated copper, and copper wire technology are all under research and mass verification. How to improve the photoelectric conversion efficiency of the solar cell and reduce the cost per watt has become an important topic for researchers. Summary of the Invention

[0003] This application provides a method for manufacturing a solar cell, aiming to improve the photoelectric conversion efficiency of the solar cell and reduce the cost per watt.

[0004] The manufacturing method includes the following steps S01 to S04:

[0005] Step S01: Form a plurality of filling structures on the surface of the cell substrate. The filling structures extend along a first direction parallel to the surface of the cell substrate. The filling structure includes a first part close to the cell substrate and a second part far from the cell substrate. The width of the second part along a second direction is smaller than the width of the first part along the second direction. The second direction is parallel to the surface of the cell substrate and intersects with the first direction.

[0006] Step S02: Form a mask layer on the surface of the cell substrate. At least a part of the filling structure is located within the mask layer.

[0007] Step S03: Remove the plurality of filling structures to form a plurality of cavities within the mask layer.

[0008] Step S04: Form a plurality of grid lines within the plurality of cavities. The plurality of grid lines are electrically connected to the cell substrate.

[0009] In some embodiments, the cross-sectional shape of the above-mentioned filling structure along the second direction is a regular trapezoid.

[0010] In some embodiments, the first part and the second part of the above-mentioned filling structure are connected. The cross-sectional shape of the first part along the second direction is a rectangle, and the cross-sectional shape of the second part along the second direction is a regular trapezoid. Alternatively, the cross-sectional shape of the first part along the second direction is a regular trapezoid, and the cross-sectional shape of the second part along the second direction is a rectangle. Alternatively, the filling structure further includes a third part disposed on the side of the second part away from the first part. The first part, the second part, and the third part are connected in sequence. The cross-sectional shape of the first part along the second direction is a rectangle, the cross-sectional shape of the second part along the second direction is a regular trapezoid, and the cross-sectional shape of the third part along the second direction is a rectangle.

[0011] In some embodiments, the above-mentioned plurality of filling structures are formed on the surface of the battery substrate by using a laser transfer process.

[0012] In some embodiments, the material of the filling structure includes polyethylene glycol, ethylene glycol, hydrophobic silica, polyvinylpyrrolidone, and water. Removing the plurality of filling structures includes: removing the plurality of filling structures by means of water washing.

[0013] In some embodiments, the cavity includes a first opening close to the battery substrate and a second opening far from the battery substrate, and the width of the second opening in the second direction is smaller than the width of the first opening in the second direction.

[0014] In some embodiments, a plurality of grid lines are formed in the plurality of cavities by using an electroplating process.

[0015] In some embodiments, before forming the plurality of grid lines, the preparation method further includes: forming a seed layer on the surface of the battery substrate.

[0016] In some embodiments, after forming the plurality of grid lines, the preparation method further includes: removing the mask layer to expose the plurality of grid lines; forming a protective layer that covers the plurality of grid lines.

[0017] In some embodiments, a mask layer is formed on the surface of the battery substrate by using an inkjet printing process or a screen printing process.

[0018] In the embodiments of the present application, first, a plurality of filling structures are formed on the surface of the battery substrate, and on this basis, a mask layer is formed such that at least a part of the filling structure is located within the mask layer. Then, the plurality of filling structures are removed to form a plurality of cavities within the mask layer. Through the above process, a mask layer with a specific morphology can be formed, and the morphology of the cavities within the mask layer is the same as a part of the morphology of the filling structure. On this basis, a plurality of grid lines are formed within the plurality of cavities, and grid lines corresponding to the morphology of the cavities can be formed, that is, the grid line morphology can be adjusted by controlling the morphology of the filling structure. Since the filling structure includes a first part close to the battery substrate and a second part far from the battery substrate, and the width of the second part in the second direction is smaller than the width of the first part in the second direction, that is, the filling structure has the characteristic of being narrow at the top and wide at the bottom. Based on this, the formed grid lines also have the characteristic of being narrow at the top and wide at the bottom, which is beneficial to realizing the efficient secondary reflection utilization of incident light, thereby realizing the improvement of the short-circuit current and conversion efficiency, and further reducing the cost per watt. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in this application, the following will briefly introduce the drawings required for use in some embodiments of this application. Obviously, the drawings in the following description are only the drawings of some embodiments of this application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams and do not represent the actual sizes of the products or the actual processes of the methods involved in the embodiments of this application.

[0020] Figure 1 Schematic flow chart of a method for preparing a solar cell provided by an embodiment of this application;

[0021] Figures 2 to 5 For Figure 1 Each step diagram of the shown preparation method;

[0022] Figure 6 Schematic structural diagram of a filling structure provided by an embodiment of this application;

[0023] Figure 7 Schematic structural diagram of another filling structure provided by an embodiment of this application;

[0024] Figure 8 Schematic structural diagram of yet another filling structure provided by an embodiment of this application;

[0025] Figure 9 Step diagram of preparing a seed layer provided by an embodiment of this application;

[0026] Figure 10 Step diagram of removing a mask layer provided by an embodiment of this application;

[0027] Figure 11 Step diagram of forming a protective layer provided by an embodiment of this application.

[0028] Reference numerals:

[0029] 10. Battery substrate; 11. Filling structure; 111. First part; 112. Second part; K0. Cavity; K1. First opening; K2. Second opening; L0. Grid line; 12. Mask layer; 13. Seed layer; 14. Protective layer. Detailed implementation manners

[0030] The following will clearly and completely describe the technical solutions in some embodiments of this application with reference to the drawings. Obviously, the described embodiments are only some embodiments of this application, rather than all embodiments. Based on the embodiments provided by this application, all other embodiments obtained by those of ordinary skill in the art belong to the scope protected by this application.

[0031] Unless the context requires otherwise, throughout the specification and claims, the term "comprising" is to be construed in an open, inclusive sense, i.e., "including, but not limited to".

[0032] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0033] When describing some embodiments, the expression "connected" and its derivatives may be used. The term "connected" should be understood in a broad sense. For example, "connected" may be a fixed connection, a detachable connection, or an integral one; it may be directly connected or indirectly connected through an intermediate medium. For example, when describing some embodiments, the term "connected" may be used to indicate that two or more components have direct physical contact or electrical contact with each other.

[0034] In addition, the use of "based on" means open and inclusive because a process, step, calculation, or other action "based on" one or more of the stated conditions or values may, in practice, be based on additional conditions or values beyond those stated.

[0035] Exemplary embodiments are described herein with reference to cross-sectional views that are idealized exemplary drawings. In the drawings, the thickness of layers and the area of regions are exaggerated for clarity. Thus, variations in the shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are contemplated. Accordingly, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein but include shape deviations caused, for example, by manufacturing. For example, an etched region shown as rectangular will typically have curved features. Thus, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shape of the regions of the device and are not intended to limit the scope of the exemplary embodiments.

[0036] In the conventional production of grid lines, since the paste is compounded of materials such as metal particles and organic resins, the surface of the cured grid lines is relatively rough and has holes, seriously affecting the secondary utilization of light. In the copper electroplating technology, the cross-section of the formed grid lines is usually in a rectangular morphology. In related research, the optical improvement can be achieved by optimizing the grid line morphology design, improving the light utilization rate, thereby enhancing the photoelectric conversion efficiency of the solar cell and reducing the cost per watt. However, the grid line morphology design will bring difficulties in the preparation process. For example, the stacked grid process has particularly high requirements for the accuracy of equipment and process.

[0037] Based on this, the present application proposes a method for preparing a solar cell, aiming to improve the photoelectric conversion efficiency of the solar cell and reduce the cost per watt. As Figure 1 shown, Figure 1 FIG. is a schematic flow chart of a method for preparing a solar cell provided by an embodiment of the present application, Figures 2 to 5 and Figure 1 FIG. is a diagram of each step of the preparation method shown.

[0038] The preparation method includes the following steps S01 to S04:

[0039] Step S01: As Figure 2 shown, a plurality of filling structures 11 are formed on the surface P1 of the cell substrate 10, and the filling structures 11 extend along a first direction Y parallel to the surface P1 of the cell substrate 10. The filling structure 11 includes a first part 111 close to the cell substrate 10 and a second part 112 far from the cell substrate 10, and the width of the second part 112 in the second direction X is smaller than the width of the first part 111 in the second direction X. The second direction X is parallel to the surface P1 of the cell substrate 10 and intersects the first direction Y.

[0040] Exemplarily, the cell substrate 10 here can be a cell substrate 10 of any one type of cell such as a heterojunction cell, a tunnel oxide passivated contact cell, or a back contact photovoltaic cell.

[0041] Step S02: As Figure 3 shown, a mask layer 12 is formed on the surface P1 of the cell substrate 10, and at least part of the filling structure 11 is located within the mask layer 12.

[0042] Step S03: As Figure 4 shown, the plurality of filling structures 11 are removed, so that a plurality of cavities K0 are formed within the mask layer 12.

[0043] Step S04: As Figure 5 shown, a plurality of grid lines L0 are formed within the plurality of cavities K0, and the plurality of grid lines L0 are electrically connected to the cell substrate 10.

[0044] In the embodiment of the present application, first, a plurality of filling structures 11 are formed on the surface P1 of the cell substrate 10, and on this basis, a mask layer 12 is formed, so that at least part of the filling structure 11 is located within the mask layer 12. Then, the plurality of filling structures 11 are removed, so that a plurality of cavities K0 are formed within the mask layer 12. Through the above process, as Figure 4As shown, a mask layer 12 capable of forming a specific morphology can be formed. The morphology of the cavity K0 in the mask layer 12 is the same as part of the morphology of the filling structure 11. On this basis, by forming multiple grid lines L0 in the multiple cavities K0, grid lines L0 corresponding to the morphology of the cavity K0 can be formed, that is, the morphology of the grid lines L0 can be adjusted by controlling the morphology of the filling structure 11.

[0045] Since the filling structure 11 includes a first part 111 close to the battery substrate 10 and a second part 112 far from the battery substrate 10, and the width of the second part 112 in the second direction X is smaller than the width of the first part 111 in the second direction X, that is, the filling structure 11 has the characteristic of being narrow at the top and wide at the bottom. Based on this, the formed grid lines L0 also have the characteristic of being narrow at the top and wide at the bottom, which is beneficial to realizing the efficient secondary reflection and utilization of incident light, thereby realizing the improvement of the short-circuit current and conversion efficiency, that is, the output power per unit area of the solar cell is increased, and further the cost per watt is reduced.

[0046] In some embodiments, as Figure 2 shown, the cross-sectional shape of the above-mentioned filling structure 11 in the second direction X is a regular trapezoid.

[0047] Based on the preparation method mentioned above, the morphology of the grid lines L0 can be adjusted by controlling the morphology of the filling structure 11. In the embodiments of the present application, by setting the cross-sectional shape of the filling structure 11 in the second direction X to be a regular trapezoid, the finally prepared grid lines L0 can also have a regular trapezoid morphology.

[0048] It can be understood that due to certain errors in the preparation process, the morphology of the actually prepared grid lines L0 may not be an ideal completely regular shape. In other words, within a certain error range, the cross-sectional shapes of the filling structure 11 and the finally prepared grid lines L0 in the second direction X are regular trapezoids.

[0049] When the solar cell is working, the regular trapezoidal grid lines L0 can greatly reduce the loss of incident light on the grid lines L0, improve the short-circuit current and photoelectric conversion efficiency of the battery, that is, the output power per unit area of the solar cell is increased, and further the cost per watt is reduced.

[0050] In some embodiments, as Figure 6 shown, Figure 6 is a schematic structural diagram of a filling structure provided by an embodiment of the present application. The first part 111 and the second part 112 of the above-mentioned filling structure 11 are connected. The cross-sectional shape of the first part 111 in the second direction X is a rectangle, and the cross-sectional shape of the second part 112 in the second direction X is a regular trapezoid.

[0051] Or, as Figure 7 shown, Figure 7It is a schematic structural diagram of another filling structure provided by an embodiment of the present application. The cross-sectional shape of the first part 111 along the second direction X is a regular trapezoid, and the cross-sectional shape of the second part 112 along the second direction is a rectangle.

[0052] Or, as Figure 8 shown, Figure 8 It is a schematic structural diagram of yet another filling structure provided by an embodiment of the present application. The filling structure 11 further includes a third part 113 disposed on the side of the second part 112 away from the first part 111. The first part 111, the second part 112, and the third part 113 are connected in sequence. The cross-sectional shape of the first part 111 along the second direction X is a rectangle, the cross-sectional shape of the second part 112 along the second direction X is a regular trapezoid, and the cross-sectional shape of the third part 113 along the second direction X is a rectangle.

[0053] The morphologies of the above various filling structures 11 can all be summarized as a morphology of "narrow at the top and wide at the bottom". Based on this, the formed grid line L0 also has the characteristic of being narrow at the top and wide at the bottom, which is beneficial to realizing the efficient secondary reflection and utilization of incident light, thereby realizing the improvement of the short-circuit current and conversion efficiency, that is, the output power per unit area of the solar cell is increased, and further the cost per watt is reduced.

[0054] In the embodiment of the present application, since the morphology of the grid line L0 can be adjusted by controlling the morphology of the filling structure 11, and the filling structure 11 includes a plurality of parts connected in sequence by stacking, by finely adjusting the morphologies of each part, the morphology of the filling structure 11 can be finely controlled, and further the morphology of the grid line L0 has high controllability and can be adjusted according to requirements.

[0055] In some embodiments, in step S01, a laser transfer process is used to form the above-mentioned plurality of filling structures 11 on the surface P1 of the battery substrate 10.

[0056] Exemplarily, the laser transfer film is designed in a regular trapezoid, so that the cross-sectional shape of the formed filling structure 11 along the second direction X is a regular trapezoid.

[0057] In some embodiments, the material of the filling structure 11 includes polyethylene glycol, ethylene glycol, hydrophobic silica, polyvinylpyrrolidone, and water. Removing the plurality of filling structures 11 in step S03 includes: removing the plurality of filling structures 11 by means of water washing.

[0058] The materials of the above-mentioned filling structure 11 have good aqueous thixotropy, the preparation method is simple, and it is easy to wash with water. By using the water washing method, the filling structure 11 can be efficiently removed, avoiding material residue from affecting the subsequent preparation and conductive performance of the grid line L0.

[0059] In some embodiments, such as Figure 1As shown, the cavity K0 includes a first opening K1 close to the battery substrate 10 and a second opening K2 far from the battery substrate 10. The width of the second opening K2 along the second direction X is smaller than the width of the first opening K1 along the second direction X.

[0060] Exemplarily, the first opening K1 can be understood as being formed corresponding to the first part 111 of the filling structure 11, and the second opening K2 can be understood as being formed corresponding to the second part 112. The width of the second opening K2 along the second direction X being smaller than the width of the first opening K1 along the second direction X enables the formed gate line L0 to have a "narrower at the top and wider at the bottom" morphology when preparing the gate line L0 subsequently, which is beneficial for realizing efficient secondary reflection utilization of incident light, improving the short-circuit current and conversion efficiency, that is, increasing the output power per unit area of the solar cell, and thus reducing the cost per watt.

[0061] In some embodiments, in step S04, a plating process is used to form multiple gate lines L0 in the multiple cavities K0.

[0062] Exemplarily, the copper plating technology uses low-cost copper as the main conductive material, and copper has excellent conductivity close to that of pure silver. Moreover, the plating process makes the width of the formed gate line L0 along the second direction X smaller. For example, taking the heterojunction cell HJT-210 half-cell as an example, the size of the surface P1 of the battery substrate 10 is 210mm * 105mm, and the width of the multiple gate lines L0 formed by the plating process along the second direction X is 20um.

[0063] The smaller width of the gate line L0 can result in a smaller light-shielding area, which is beneficial for improving the photoelectric conversion efficiency of the solar cell, that is, increasing the output power per unit area of the solar cell, and thus reducing the cost per watt.

[0064] In some embodiments, before forming the multiple gate lines L0, the preparation method further includes: forming a seed layer 13 on the surface P1 of the battery substrate 10.

[0065] Exemplarily, as Figure 9 shown, Figure 9 is a step diagram for preparing the seed layer provided by the embodiment of the present application. That is, before forming the filling structure 11 in step S01, a seed layer 13 can be locally formed on the surface P1 of the battery substrate 10. The "local" here can be understood as the part of the surface P1 of the battery substrate 10 where the gate line L0 needs to be prepared.

[0066] Alternatively, in some other embodiments, a seed layer 13 can also be formed over the entire surface of the battery substrate 10. After forming the gate line L0 through steps S01 to S04, the seed layer 13 in the area not covered by the gate line L0 is then removed.

[0067] Exemplarily, taking the HJT-210 half-cell of the heterojunction battery as an example, the thickness of the seed layer 13 is 100 nm, and the material includes copper. On the one hand, the seed layer 13 can increase the bonding force between the gate line L0 and the battery substrate 10, and on the other hand, it is also beneficial to improve the uniformity of the gate line L0 in the subsequent process of preparing the gate line L0.

[0068] In some embodiments, as Figures 10 to 11 shown, Figure 10 is the step diagram for removing the mask layer provided by the embodiment of the present application, Figure 11 is the step diagram for forming the protective layer provided by the embodiment of the present application.

[0069] That is, after forming multiple gate lines L0 in step S04, the above preparation method further includes:

[0070] As Figure 10 shown, removing the mask layer 12 to expose multiple gate lines L0.

[0071] As Figure 11 shown, forming a protective layer 14, and the protective layer 14 covers multiple gate lines L0.

[0072] Exemplarily, the protective layer 14 can be a metal protective layer, and its material can include tin or silver, etc. Or, the protective layer 14 can also be an inorganic protective layer, and its material can include silicon oxide or transparent conductive oxide, etc. Or, the protective layer 14 can also be an organic protective layer, and its material can include polymer resin or antioxidant, etc.

[0073] In some embodiments, in step S02, an inkjet printing process or a screen printing process is used to form a mask layer 12 on the surface of the battery substrate 10.

[0074] Exemplarily, the mask layer 12 is an organic mask layer. Both the inkjet printing process and the screen printing process have relatively mature equipment and process flows, and can achieve precise control of the film layer thickness. By controlling the thickness of the mask layer 12, the expected thickness of the gate line L0 can be formed after removing the filling structure 11.

[0075] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application, thinking of changes or substitutions, should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for preparing a solar cell, characterized in that: include: A plurality of filling structures are formed on the surface of the battery substrate, wherein the filling structures extend along a first direction parallel to the surface of the battery substrate; the filling structures include a first portion close to the battery substrate and a second portion away from the battery substrate, wherein a width of the second portion along the second direction is smaller than a width of the first portion along the second direction; The second direction is parallel to the surface of the battery substrate and intersects with the first direction; forming a mask layer on the surface of the battery substrate, wherein at least a portion of the filling structure is located within the mask layer; removing the plurality of filling structures to form a plurality of cavities in the mask layer; A plurality of grid lines are formed in the plurality of cavities, and the plurality of grid lines are electrically connected to the battery substrate.

2. The preparation method according to claim 1, characterized in that: A cross-section of the filling structure along the second direction is in the shape of a regular trapezoid.

3. The preparation method according to claim 1, characterized in that: The first portion is connected to the second portion, a cross-section of the first portion along the second direction is a rectangular shape, and a cross-section of the second portion along the second direction is a regular trapezoid shape; or, The cross-section shape of the first portion along the second direction is a regular trapezoid, and the cross-section shape of the second portion along the second direction is a rectangle; or, The filling structure also includes a third part arranged on a side of the second part away from the first part, and the first part, the second part and the third part are connected in sequence; the shape of the cross-section of the first part along the second direction is a rectangle, the shape of the cross-section of the second part along the second direction is a regular trapezoid, and the shape of the cross-section of the third part along the second direction is a rectangle.

4. The preparation method according to claim 1, characterized in that: The plurality of filling structures are formed on the surface of the battery substrate by using a laser transfer process.

5. The preparation method according to claim 1, characterized in that: The material of the filling structure includes polyethylene glycol, ethylene glycol, hydrophobic silica, polyvinyl pyrrolidone and water; Removing the plurality of filling structures comprises: The multiple filling structures are removed by water washing.

6. The preparation method according to claim 1, characterized in that: The cavity includes a first opening close to the battery substrate and a second opening far from the battery substrate, wherein a width of the second opening along the second direction is smaller than a width of the first opening along the second direction.

7. The preparation method according to claim 1, characterized in that: The plurality of gate lines are formed in the plurality of cavities by using an electroplating process.

8. The preparation method according to claim 7, characterized in that: Before forming the plurality of gate lines, the preparation method further includes: forming a seed layer on the surface of the battery substrate.

9. The preparation method according to claim 1, characterized in that: After forming the plurality of gate lines, the preparation method further comprises: removing the mask layer to expose the plurality of gate lines; A protection layer is formed, wherein the protection layer covers the plurality of gate lines.

10. The preparation method according to claim 1, characterized in that: The mask layer is formed on the surface of the battery substrate by using an inkjet printing process or a screen printing process.

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