Solar cell and preparation method thereof

Abstract

The invention discloses a solar cell and a preparation method thereof, and relates to the technical field of solar cell manufacturing, and the method specifically comprises the steps: preparing a first photosensitive layer on a cell main body provided with a metal seed layer, and forming a first groove in the first photosensitive layer; wherein the first groove is filled with a filling material; preparing a second photosensitive layer on the first photosensitive layer in a laminating manner, forming a second groove in the second photosensitive layer, and removing part of the filling material filled in the first groove; wherein the second groove corresponds to the first groove, and the projection of the side wall of the second groove is located in the first groove; growing metal fine grids in the first groove and the second groove by using an electroplating method; and removing the first photosensitive layer and the second photosensitive layer. According to the embodiment, the first groove and the second groove which are arranged in a stacked mode can be obtained, the height of the fine grid is guaranteed, and meanwhile the metal fine grid with the narrower width is obtained. And meanwhile, the obtained grid line is higher in strength, more solar rays can be refracted to the cell main body, and the photoelectric conversion efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell manufacturing, and in particular to a solar cell and a preparation method thereof. Background Art

[0002] At present, it has become a consensus that the use of copper electroplating to grow metal fine grids to replace the production method of sintering fine grids by silver paste printing process can greatly reduce the cost of silver paste. In the prior art, photosensitive materials are usually used to make grooves for growing metal fine grids. However, since the grooves on the photosensitive material are prepared by photolithography and development process, the thicker the photosensitive material, the thicker the width and height of the corresponding grooves will be. Although the metal fine grid can meet the higher grid line height, the corresponding metal fine grid will also be wider, which is easy to cause serious shading problems. The photosensitive material is thinner, and although a thinner metal fine grid can be obtained, the grid line height cannot meet the preparation requirements. Therefore, it is urgent to provide a method for preparing a solar cell that can prepare a tall and thin metal fine grid. Summary of the invention

[0003] In view of this, an embodiment of the present invention provides a solar cell and a method for preparing the same. By sequentially preparing a first photosensitive layer and a second photosensitive layer, a first groove and a second groove arranged in a stacked manner can be obtained. In this way, after growing a metal fine grid, a metal fine grid with a narrower width can be obtained while ensuring the height of the fine grid. At the same time, since the projection of the side wall of the second groove is located in the first groove, a metal fine grid with a cross-section approximately in the shape of a trapezoid can be obtained. Compared with a vertical metal fine grid, the grid line strength is higher, and more sunlight can be refracted to the battery body, thereby improving the photoelectric conversion efficiency.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention provides a method for preparing a solar cell, comprising: step 1, preparing a first photosensitive layer on a battery body provided with a metal seed layer, and forming a first groove on the first photosensitive layer; wherein the first groove is filled with a filling material; step 2, preparing a second photosensitive layer by stacking on the first photosensitive layer, and forming a second groove in the second photosensitive layer, and removing part of the filling material filled in the first groove; wherein the second groove corresponds to the first groove, and the projection of the side wall of the second groove is located in the first groove; step 3, growing metal fine grids in the first groove and the second groove by electroplating; step 4, removing the first photosensitive layer and the second photosensitive layer.

[0006] Optionally, step 1 includes: step 11, coating a first photosensitive material on a battery body provided with a metal seed layer, and drying the first photosensitive material; step 12, performing interval exposure on the dried first photosensitive material to obtain a first photosensitive layer; step 13, cleaning the first photosensitive layer with a developer to obtain the first groove; step 14, filling the first groove with a filling material.

[0007] Optionally, the step 2 includes: step 21, coating a second photosensitive material on the first photosensitive layer and the filling material, and drying the second photosensitive material; step 22, performing interval exposure on the dried second photosensitive material to obtain a second photosensitive layer; step 23, using a developer to clean the second photosensitive layer and the first groove to obtain the second groove, and removing part of the filling material filled in the first groove to form a bevel connection between the first groove and the second groove.

[0008] Optionally, the width of the first groove is 5 μm to 8 μm; and / or the width of the second groove is 4 μm to 6 μm.

[0009] Optionally, the thickness of the first photosensitive layer is 5 μm to 8 μm; and / or the thickness of the second photosensitive layer is 4 μm to 6 μm.

[0010] Optionally, the first photosensitive material and / or the second photosensitive material is ink or photoresist containing a photoinitiator; and / or the filling material is ink or photoresist not containing a photoinitiator.

[0011] Optionally, the step 4 includes: removing the first photosensitive layer, the second photosensitive layer and the metal seed layer not covered by the metal fine grid by using an alkaline solution.

[0012] In a second aspect, the present invention provides a solar cell prepared by the above-mentioned preparation method, comprising: a battery body; and a plurality of metal fine grids arranged at intervals on the battery body; wherein the metal fine grids include a first fine grid and a second fine grid stacked together; and the width of the first fine grid is greater than the width of the second fine grid.

[0013] The technical solution of the first aspect of the above invention has the following advantages or beneficial effects: by sequentially preparing the first photosensitive layer and the second photosensitive layer, a first groove and a second groove arranged in a stacked manner can be obtained, so that after growing the metal fine grid, a metal fine grid with a narrower width can be obtained while ensuring the height of the fine grid. At the same time, since the projection of the side wall of the second groove is located in the first groove, a metal fine grid with a cross-section approximately in the shape of a trapezoid can be obtained, and compared with a vertical metal fine grid, the grid line strength is higher, and more sunlight can be refracted to the battery body, thereby improving the photoelectric conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to better understand the present invention and do not constitute an improper limitation of the present invention.

[0015] Figure 1 is a schematic flow chart of a method for preparing a solar cell according to an embodiment of the present invention;

[0016] Figure 2 is a cross-sectional structural diagram of a battery corresponding to step S101 according to an embodiment of the present invention;

[0017] Figure 3 is a cross-sectional structural diagram of a battery corresponding to step S102 according to an embodiment of the present invention;

[0018] Figure 4 is a cross-sectional structural diagram of a battery corresponding to step S103 according to an embodiment of the present invention;

[0019] Figure 5 is a cross-sectional structural diagram of a battery corresponding to step S104 according to an embodiment of the present invention;

[0020] Figure 6 is a schematic flow chart of a specific preparation process of step S101 according to an embodiment of the present invention;

[0021] Figure 7 is a cross-sectional structural diagram of a battery corresponding to step S601 according to an embodiment of the present invention;

[0022] Figure 8 is the exposure position of the first photosensitive material in step S602 of the embodiment of the present invention;

[0023] Fig. 9 is the position of the first photosensitive layer obtained after the first photosensitive material undergoes polymerization reaction after exposure in step S602 according to an embodiment of the present invention;

[0024] Fig.10 is a cross-sectional structural diagram of a battery corresponding to step S603 according to an embodiment of the present invention;

[0025] Fig.11 is a schematic flow chart of a specific preparation process of step S102 according to an embodiment of the present invention;

[0026] Fig.12 is a cross-sectional structural diagram of a battery obtained in step S1101 according to an embodiment of the present invention;

[0027] Fig.13 is the position where the second photosensitive material is exposed in step S1102 according to an embodiment of the present invention;

[0028] Fig.14is a schematic structural diagram of the second photosensitive layer obtained after exposure in step S1102 according to an embodiment of the present invention.

[0029] The reference numerals are as follows:

[0030] 1-battery body; 2-first photosensitive layer; 21-first groove; 3-second photosensitive layer; 31-second groove; 4-metal fine grid; 41-first fine grid; 42-second fine grid. DETAILED DESCRIPTION

[0031] A solar cell is a photoelectric semiconductor wafer that uses sunlight to generate electricity directly. It is also called a "solar chip" or "photovoltaic cell". As long as it is illuminated by light that meets certain illumination conditions, it can instantly output voltage and generate current in the presence of a circuit. In physics, it is called solar photovoltaic (PV), or photovoltaic for short. In order to conveniently and clearly describe the method for preparing a solar cell and the solar cell of the present invention, the following exemplary embodiments of the present invention are described in conjunction with the accompanying drawings, which include various details of the embodiments of the present invention to facilitate understanding, and they should be considered to be merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted in the following description.

[0032] The existing metal fine grid preparation process generally includes: coating photosensitive material → exposing the photosensitive material to form a photosensitive layer → using a developer to clean the photosensitive layer to obtain a groove → growing the metal fine grid in the groove. Since the formation of the groove is actually a morphological change after the photosensitive material undergoes a polymerization reaction, the photosensitive layer converted into a solid state due to the polymerization reaction can be retained during the cleaning with the developer to obtain a groove for the growth of the metal fine grid. Therefore, the actual coating thickness of the photosensitive material should not be too thick, which will cause the part of the photosensitive material close to the battery body to be insufficiently exposed and unable to fully undergo a polymerization reaction, thereby causing the outline of the groove to be unclear, and affecting the width and height of the grown metal fine grid. Therefore, the present invention prepares the photosensitive layer twice to form different parts of the metal fine grid respectively, thereby ensuring the height of the fine grid and reducing the width of the fine grid, thereby improving the overall performance of the solar cell.

[0033] In one embodiment of the present invention, Figure 1 As shown, this embodiment provides a method for preparing a solar cell, and the preparation method may include the following steps:

[0034] Step S101, preparing a first photosensitive layer 2 on a battery body 1 provided with a metal seed layer, and forming a first groove 21 on the first photosensitive layer 2; wherein the first groove 21 is filled with a filling material;

[0035] Step S102, preparing a second photosensitive layer 3 by stacking on the first photosensitive layer 2, and forming a second groove 31 in the second photosensitive layer 3, and removing part of the filling material filled in the first groove 21; wherein the second groove 31 corresponds to the first groove 21, and the projection of the side wall of the second groove 31 is located in the first groove 21;

[0036] Step S103, growing a metal fine gate 4 in the first groove 21 and the second groove 31 by electroplating;

[0037] Step S104, removing the first photosensitive layer 2 and the second photosensitive layer 3.

[0038] The metal seed layer refers to a layer used to provide a metal source for growing metal fine gates. Different metal fine gates can be grown based on different metal seed layers. For example, when the metal seed layer is a copper seed layer, the grown metal fine gate is a copper gate line.

[0039] For example, Figures 2 to 5 The battery cross-sectional structure obtained from the above steps S101 to S104 is described in detail. Figure 2 Corresponding to step S101, a cross-sectional structure diagram of a battery is shown in which a first groove 21 is prepared in the first photosensitive layer 2 and a filling material is filled in the first groove 21; Figure 3 Corresponding to step S102, a schematic diagram of a cross-sectional structure of a battery is shown in which a second photosensitive layer 3 is prepared outside the first photosensitive layer 2 and a second groove 31 is provided on the second photosensitive layer 3; Figure 4 Corresponding to step S103, a schematic diagram of the cross-sectional structure of the battery after the metal fine grid 4 is grown in the first groove 21 and the second groove 31 is shown. Figure 5 Corresponding to step S104, a schematic diagram of the cross-sectional structure of the battery is shown in which only the metal fine grid 4 is retained after the first photosensitive layer 2 and the second photosensitive layer 3 are removed.

[0040] In order to ensure that the filling material in the first groove 21 is in a filled state, so as to avoid uneven coating of the second photosensitive layer 3 during the coating process, according to Figure 2 It can be seen from the cross-sectional structure that in an optional embodiment of the present invention, when the filling material is applied, the filling material can overflow the first groove 21 and form a filling layer on the first photosensitive layer 2 to ensure that a smooth surface can still be obtained after the first groove 21 is filled, and the second photosensitive layer 3 is subsequently prepared on the smooth surface.

[0041] In an optional embodiment, the specific preparation process of step S101 can be as follows: Figure 6 As shown, including:

[0042] Step S601, coating a first photosensitive material on the battery body 1 provided with a metal seed layer, and drying the first photosensitive material;

[0043] Step S602, performing interval exposure on the dried first photosensitive material to obtain a first photosensitive layer 2;

[0044] Step S603, washing the first photosensitive layer 2 with a developer to obtain a first groove 21;

[0045] Step S604 , filling the first groove 21 with a filling material.

[0046] Among them, the specific drying temperature for drying the first photosensitive material in step S601 is 80℃~90℃, and the drying time is 5min~10min. For the developer in step S603, in an optional embodiment, it can be a Na2CO3 solution with a mass percentage of 0.8~1.3wt%, for example, a 1.0wt% Na2CO3 solution, and the cleaning temperature is 25℃~35℃, preferably 30℃±2.

[0047] Below, Figures 7 to 10 As an example, the process from step S601 to step S604 is described in detail. Figure 7 Corresponding to step S601, a schematic diagram of a cross-sectional structure of a battery obtained after the first photosensitive material is coated on one main surface of the battery body 1 and dried is shown; Figure 8 and Fig. 9 Corresponding to step S602, the position where the first photosensitive material is exposed and the position of the first photosensitive layer 2 obtained after the first photosensitive material undergoes polymerization reaction after exposure are shown; Fig.10 Corresponding to step S603, the position of the first groove 21 obtained after cleaning the first photosensitive layer 2 is shown. Figures 7 to 10 The negative photosensitive material is used as the first photosensitive material for preparation, so the exposed area will undergo polymerization reaction to form the first photosensitive layer 2, and the unexposed area will be washed by the developer to obtain the first groove 21. As for the positive photosensitive material, the photosensitive characteristics of the negative photosensitive material are exactly opposite, the unexposed part will undergo polymerization reaction, and the exposed part will undergo physical changes and can be washed by the developer, so the interval exposure in step S602 is for different types of first photosensitive materials. In view of the different characteristics of the positive photosensitive material and the negative photosensitive material, the exposure position is also different, but the position of the first groove 21 to be obtained in the end is the same, so the specific exposure position matches the photosensitive characteristics of the first photosensitive material.

[0048] In a further optional embodiment, step S102 also includes a plurality of specific preparation steps, such as Fig.11 As shown, including:

[0049] Step S1101, coating a second photosensitive material on the first photosensitive layer 2 and the filling material, and drying the second photosensitive material;

[0050] Step S1102, performing interval exposure on the dried second photosensitive material to obtain a second photosensitive layer 3;

[0051] Step S1103 , using a developer to clean the second photosensitive layer 3 and the first groove 21 , to obtain the second groove 31 , and to remove a portion of the filling material filled in the first groove 21 , so as to form an inclined connection between the first groove 21 and the second groove 31 .

[0052] Among them, similar to step S601 and step S603, the specific drying temperature for drying the second photosensitive material in step S1101 is 80℃~90℃, and the drying time is 5min~10min. For the developer in step 1103, in an optional embodiment, it can be a Na2CO3 solution with a mass percentage of 0.8~1.3wt%, such as a 1.0wt% Na2CO3 solution, and the cleaning temperature is 25℃~35℃, preferably 30℃±2.

[0053] For example, Figure 12 to Figure 14 The schematic diagrams of the cross-sectional structures of the batteries obtained in step S1101 and step S1102 are shown respectively. Specifically, Fig.12 Corresponding to step S1101, a schematic diagram of the cross-sectional structure of the battery after coating the second photosensitive material on the first photosensitive layer 2 and the filling material is shown; Fig.13 and Fig.14 Corresponding to step S1102, the position where the second photosensitive material is exposed and the second photosensitive layer 3 obtained after exposure are respectively shown. Figure 12 to Figure 14 Exposure is also performed using a negative photosensitive material as an example. In an optional embodiment, in order to avoid the influence of exposure on the stacked photosensitive materials, the first photosensitive material and the second photosensitive material have the same photosensitive properties, that is, they are both negative photosensitive materials or both positive photosensitive materials.

[0054] In a further optional embodiment, the first photosensitive material and / or the second photosensitive material is an ink or photoresist containing a photoinitiator, and the filling material is an ink or photoresist that does not contain a photoinitiator. It is understandable that in the process of exposing the second photosensitive material, the filling material is also filled inside the first groove 21, and it is necessary to ensure that the filling material does not physically react due to exposure, so the filling material cannot contain a photoinitiator. It is understandable that the higher the photoinitiator content, the faster the polymerization reaction occurs. In an optional embodiment, the photoinitiator content of the negative photosensitive material of the present invention is 5% to 10%, which is similar to the photoinitiator content of inks and photoresists commonly sold on the market.

[0055] In addition, according to Figure 3 , Figure 4 as well as Fig.14 It can be seen that since the side wall projection of the second groove 31 is located inside the left and right side walls of the first groove 21, that is, the opening of the second groove 31 will be smaller than the opening of the first groove 21, therefore, when the second photosensitive layer 3 and the first groove 21 are cleaned with the developer in step S1103, the side wall of the second groove 31 formed will partially block the developer, making it impossible for the developer to completely clean the inside of the first groove 21, and therefore only part of the filling material can be cleaned, that is, part of the filling material between the side wall of the second groove 31 and the side wall of the first groove 21 is retained, so that after cleaning, a bevel connection is formed between the first groove 21 and the second groove 31.

[0056] Since the thickness of the photosensitive material actually determines the width and height of the groove, in an optional embodiment, the thickness of the first photosensitive layer 2 is 5 μm to 8 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, etc., and the corresponding width and depth of the first groove 21 are also 5 μm to 8 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, etc. In another optional embodiment, the thickness of the second photosensitive layer 3 is 4 μm to 6 μm, such as 4 μm, 4.5 μm, 5.5 μm, 6 μm, etc., and the corresponding width and depth of the second groove 31 are also 4 μm to 6 μm, such as 4 μm, 4.5 μm, 5.5 μm, 6 μm, etc.

[0057] Regarding the specific process of removing the first photosensitive layer 2 and the second photosensitive layer 3 in step S104, an optional embodiment may include: using an alkaline solution to remove the first photosensitive layer 2, the second photosensitive layer 3 and the metal seed layer not covered by the metal fine grid. It is understandable that in order to achieve a better removal effect, an alkaline solution with a higher concentration is usually selected to remove the first photosensitive layer 2, the second photosensitive layer 3 and the metal seed layer. It should be noted that in the process of removing the metal seed layer, the metal fine grid will also be partially etched, but because the thickness of the metal seed layer is usually very thin, only about 100nm, the impact on the width and height of the fine grid is very small and can be ignored.

[0058] In summary, the method for preparing a solar cell provided by an embodiment of the present invention can obtain a first groove and a second groove that are stacked by sequentially preparing a first photosensitive layer and a second photosensitive layer, so that after growing a metal fine grid, a metal fine grid with a narrower width can be obtained while ensuring the height of the fine grid. At the same time, since the projection of the side wall of the second groove is located in the first groove, a metal fine grid with a cross-section approximately trapezoidal can be obtained. Compared with a vertical metal fine grid, the grid line strength is higher, and more sunlight can be refracted to the battery body, thereby improving the photoelectric conversion efficiency.

[0059] Likewise Figure 5 For example, the solar cell prepared by the above preparation method provided by the present invention is specifically described, including: a battery body 1; and a plurality of metal fine grids 4 arranged at intervals on the battery body 1; wherein the metal fine grids 4 include a first fine grid 41 and a second fine grid 42 stacked together; the width of the first fine grid 41 is greater than the width of the second fine grid 42.

[0060] Based on the description of the above preparation method, it can be known that the first fine gate 41 is obtained by growing a metal fine gate in the first groove 21, and the second fine gate 42 is obtained by growing a metal fine gate in the second groove 31. Due to the growth restrictions of the first groove 21 and the second groove 31, the metal fine gate will continue to grow in the thickness direction along the side walls of the first groove 21 and the second groove 31 under the action of electroplating. With the control of the preparation time, it is ultimately ensured that the thickness of the metal fine gate 4 will not exceed the upper surface of the second photosensitive layer 3.

[0061] In an optional embodiment, the width of the first fine grid 41 is 5μm to 8μm, such as 5μm, 6μm, 7μm, 8μm, etc.; the width of the second fine grid 42 is 4μm to 6μm, such as 4μm, 4.5μm, 5.5μm, 6μm, etc. It can be understood that since there is no technical solution for preparing the photosensitive layer in layers in the prior art, only one photosensitive layer is prepared, and if the thickness of the photosensitive layer is set to the sum of the thickness of the first photosensitive layer 2 and the second photosensitive layer 3 in the present invention (i.e., 9μm to 14μm), then the corresponding groove width and depth are also approximately 9μm to 14μm, and the width of the grown metal fine grid 4 is also 9μm to 14μm, which is much wider than the 5μm to 8μm of the first fine grid 41 and the 4μm to 6μm of the second fine grid 42 provided in the embodiment of the present invention. It can be seen that the method for preparing a solar cell and the prepared solar cell provided by the embodiment of the present invention can reduce the width of the metal fine grid by half under the condition of the same grid line height, thereby greatly reducing the light shielding problem caused by the metal fine grid.

[0062] Moreover, based on the above-mentioned preparation process, the top surface of the first fine grid 41 obtained in the embodiment of the present invention is connected to the bottom surface of the second fine grid 42 through an inclined surface, so that the overall interface of the metal fine grid 4 can be a trapezoidal structure, which effectively increases the overall strength of the grid line. It should be noted that although the first photosensitive layer 2 and the second photosensitive layer 3 are prepared in layers, the first fine grid 41 and the second fine grid 42 are actually deposited at one time, and there is no risk of increased metal contact resistance and stress separation caused by layered preparation.

[0063] In summary, the solar cell provided by the embodiment of the present invention can obtain a metal fine grid with a narrower width while ensuring the height of the fine grid. At the same time, a metal fine grid with a cross-section approximately in a trapezoidal shape is obtained, which has a higher grid line strength than a vertical metal fine grid and can refract more sunlight to the battery body, thereby improving the photoelectric conversion efficiency.

[0064] The introduction provided in the above steps is only used to help understand the structure, method and core idea of ​​the present invention. For ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also belong to the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a solar cell, characterized in that: include: Step 1, preparing a first photosensitive layer (2) on a battery body (1) provided with a metal seed layer, and forming a first groove (21) on the first photosensitive layer (2); wherein a filling material is filled in the first groove (21); Step 2, preparing a second photosensitive layer (3) by stacking on the first photosensitive layer (2), and forming a second groove (31) in the second photosensitive layer (3), and removing part of the filling material filled in the first groove (21); wherein the second groove (31) corresponds to the first groove (21), and the projection of the side wall of the second groove (31) is located in the first groove (21); Step 3, growing a metal fine grid (4) in the first groove (21) and the second groove (31) by electroplating; Step 4: removing the first photosensitive layer (2) and the second photosensitive layer (3).

2. The preparation method according to claim 1, characterized in that: The step 1 comprises: Step 11, coating a first photosensitive material on the battery body (1) provided with the metal seed layer, and drying the first photosensitive material; Step 12, performing interval exposure on the dried first photosensitive material to obtain a first photosensitive layer (2); Step 13, washing the first photosensitive layer (2) with a developer to obtain the first groove (21); Step 14: Fill the first groove (21) with a filling material.

3. The preparation method according to claim 1, characterized in that: The step 2 comprises: Step 21, coating a second photosensitive material on the first photosensitive layer (2) and the filling material, and drying the second photosensitive material; Step 22, performing interval exposure on the dried second photosensitive material to obtain a second photosensitive layer (3); Step 23, using a developer to clean the second photosensitive layer (3) and the first groove (21), to obtain the second groove (31), while removing part of the filling material filled in the first groove (21), so as to form an inclined connection between the first groove (21) and the second groove (31).

4. The preparation method according to claim 1, characterized in that: The width of the first groove (21) is 5 μm to 8 μm; and / or, The width of the second groove (31) is 4 μm to 6 μm.

5. The preparation method according to claim 1, characterized in that: The thickness of the first photosensitive layer (2) is 5 μm to 8 μm; and / or, The thickness of the second photosensitive layer (3) is 4 μm to 6 μm.

6. The preparation method according to claim 2, characterized in that: The first photosensitive material and / or the second photosensitive material is ink or photoresist containing a photoinitiator; and / or, The filling material is ink or photoresist that does not contain a photoinitiator.

7. The back contact solar cell according to claim 1, characterized in that: The step 4 comprises: The first photosensitive layer (2), the second photosensitive layer (3) and the metal seed layer not covered by the metal fine grid are removed using an alkaline solution.

8. A solar cell prepared according to any one of the preparation methods of claims 1 to 7, characterized in that: include: Battery body (1); and a plurality of metal fine grids (4) arranged at intervals on the battery body (1); The metal fine grid (4) comprises a first fine grid (41) and a second fine grid (42) which are stacked; The width of the first fine grid (41) is greater than the width of the second fine grid (42).

9. The solar cell according to claim 8, characterized in that: The width of the first fine grid (41) is 5 μm to 8 μm; and / or, The width of the second fine grid (42) is 4 μm to 6 μm.

10. The solar cell according to claim 8, characterized in that The top surface of the first fine grid (41) and the bottom surface of the second fine grid (42) are connected via an inclined surface.

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