Solar cell and preparation method therefor

Abstract

A solar cell and a preparation method therefor. The solar cell comprises: a battery matrix (100), and a first transparent conductive thin film (105) and first gate lines (107), which are arranged in sequence on a first surface of the battery matrix, wherein the first transparent conductive film (105) has a plurality of first regions (1051) and a second region (1052); the first gate lines (107) are disposed in the first regions (105); and in the direction of thickness of the first transparent conductive thin film (105), the thickness of each first region (1051) is greater than the thickness of each second region (1052).

Description

A solar cell and preparation method

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on June 27, 2023, with application number CN202310768657.1 and public name “A Solar Cell and Preparation Method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of photovoltaic technology, and in particular to a solar cell and a preparation method thereof. Background Art

[0003] SHJ (Silicon Heterojunction) cells, also known as HIT (Heterojunction with intrinsic thin layer) cells, offer high efficiency and high Voc. SHJ cells are typically based on N-type silicon wafers. The typical manufacturing process includes texturing, amorphous silicon, transparent conductive film (TCO), screen printing, and testing.

[0004] TCO typically uses ITO as a target material and is deposited onto the silicon wafer surface via PVD. Regarding screen printing, heterojunction currently primarily uses low-temperature paste for printing both the front and back sides of the cell. Compared to PERC, which only prints silver paste on the front side, the silver paste consumption per unit for heterojunction is currently 2-3 times that of PERC. Furthermore, the price of low-temperature paste is relatively higher than that of high-temperature paste. Therefore, the paste cost for heterojunction is much higher, and the cost pressure for heterojunction is relatively high.

[0005] The cost of heterojunction is much higher than that of PERC, so it is necessary to continuously improve the efficiency advantages of heterojunction batteries in order to improve the competitiveness of heterojunction batteries themselves.

[0006] Summary of the Invention

[0007] According to some embodiments of the present disclosure, a solar cell is provided, comprising: a cell substrate, a first transparent conductive film and a first grid line sequentially disposed on a first surface of the cell substrate; the first transparent conductive film having a plurality of first regions for arranging the first grid lines on a side facing away from the cell substrate, and a second region located outside the first region; the first grid lines are disposed on the first regions;

[0008] Along the thickness direction of the transparent conductive film, a first thickness of the first region is greater than a second thickness of the second region.

[0009] In some embodiments of the present disclosure, the ratio of the first thickness to the second thickness does not exceed 10.

[0010] In some embodiments of the present disclosure, a ratio of the first thickness to the second thickness does not exceed 7.

[0011] In some embodiments of the present disclosure, the first thickness is 100 nm-630 nm, and the second thickness is 90 nm-130 nm.

[0012] In some embodiments of the present disclosure, the cell substrate has a second surface disposed opposite to the first surface, and the solar cell further includes a second transparent conductive film and a second grid line sequentially disposed on the second surface;

[0013] The second transparent conductive film has a third region for arranging the second gate lines on a side facing away from the battery substrate, and a fourth region outside the third region; the second gate lines are arranged in the third region;

[0014] Along the thickness direction of the second transparent conductive film, the third thickness of the third region is greater than the fourth thickness of the fourth region.

[0015] In some embodiments of the present disclosure, the battery substrate includes a silicon substrate, an intrinsic amorphous silicon layer disposed on both surfaces of the silicon substrate, and a doped amorphous silicon layer disposed on a surface of the intrinsic amorphous silicon layer.

[0016] In some embodiments of the present disclosure, the material of the first region is selected from at least one of ITO, IWO, and IZO.

[0017] In some embodiments of the present disclosure, the material of the second region is selected from at least one of ITO, IWO, and IZO.

[0018] According to some embodiments of the present disclosure, a method for preparing a solar cell is further provided. The solar cell includes a cell substrate, a first transparent conductive film, and a first grid line. The method includes:

[0019] Preparation of a first transparent conductive film: depositing a first transparent conductive film on a first surface of the battery substrate, wherein the first transparent conductive film has a plurality of first regions spaced apart and a second region outside the first regions; a first thickness of the first region is greater than a second thickness of the second region;

[0020] Preparation of the first gate line: forming the first gate line on the first region.

[0021] In some embodiments of the present disclosure, the ratio of the first thickness to the second thickness does not exceed 10.

[0022] In some embodiments of the present disclosure, a ratio of the first thickness to the second thickness does not exceed 7.

[0023] In some embodiments of the present disclosure, the first thickness is 100 nm-630 nm, and the second thickness is 90 nm-130 nm.

[0024] In some embodiments of the present disclosure, the preparation method further comprises:

[0025] Preparation of a second transparent conductive film: depositing a second transparent conductive film on the second surface of the battery substrate, wherein the second transparent conductive film has a plurality of third regions for arranging the second grid lines and a fourth region outside the third regions on a side facing away from the battery substrate, and a third thickness of the third region is greater than a fourth thickness of the fourth region;

[0026] Preparation of the second gate line: the second gate line is disposed on the third area.

[0027] In some embodiments of the present disclosure, the battery substrate includes a silicon substrate, an intrinsic amorphous silicon layer disposed on both surfaces of the silicon substrate, and a doped amorphous silicon layer disposed on a surface of the intrinsic amorphous silicon layer.

[0028] In some embodiments of the present disclosure, the method of depositing a first transparent conductive film on the first surface of the battery substrate includes:

[0029] A first deposition is performed on the first surface of the battery substrate to form a first prefabricated film of the second thickness; a mask is covered on the surface of the first prefabricated film at a position corresponding to the second area, and then a second deposition is performed to form a second prefabricated film of a preset thickness at a position on the surface of the first prefabricated film not covered by the mask; the first prefabricated film and the second prefabricated film together form the first transparent conductive film.

[0030] In some embodiments of the present disclosure, the method of depositing a first transparent conductive film on the first surface of the battery substrate includes:

[0031] A mask is covered on the position of the first surface of the battery substrate corresponding to the second area, and a first deposition is performed to form a first prefabricated film; then the mask is removed, and a second deposition is performed to form a second prefabricated film; the first prefabricated film and the second prefabricated film together form the first transparent conductive film.

[0032] In some embodiments of the present disclosure, the materials of the first prefabricated film and the second prefabricated film are independently selected from at least one of ITO, IWO, and IZO.

[0033] In some embodiments of the present disclosure, the method of covering the mask includes: placing a hollow plate on the surface to be deposited, and aligning the hollow portion of the hollow plate with the first area.

[0034] In some embodiments of the present disclosure, preparing the first gate line includes: forming the first gate line in the first area by printing or electroplating.

[0035] In some embodiments of the present disclosure, the first gate line is formed in the first region by electroplating.

[0036] In some embodiments of the present disclosure, copper grid lines are formed in the first region by electroplating.

[0037] In some embodiments of the present disclosure, the method of forming copper grid lines in the first region by electroplating includes:

[0038] A first deposition is performed on the first surface of the battery substrate to form a first prefabricated film of the second thickness; a photosensitive resin is covered on the surface of the first prefabricated film, and the photosensitive resin is exposed and developed to form a groove exposing the surface of the first prefabricated film corresponding to the first area; a second deposition is performed in the groove to form a second prefabricated film of a preset thickness at a position on the surface of the first prefabricated film corresponding to the groove; the first prefabricated film and the second prefabricated film together form the first transparent conductive film; and copper grid lines are electroplated in the groove.

[0039] In some embodiments of the present disclosure, before electroplating the copper grid lines in the grooves, a copper seed layer is deposited on the surface of the second prefabricated film in the grooves, and the copper grid lines are electroplated on the copper seed layer.

[0040] The details of one or more embodiments of the present disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the present disclosure will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] 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 use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0042] FIG1 is a schematic cross-sectional view of a solar cell in the prior art;

[0043] FIG2 is a cross-sectional schematic diagram of a first solar cell provided in an example of this application;

[0044] FIG3 is a schematic diagram of the preparation process of a solar cell provided in an example of this application;

[0045] FIG4 is a schematic diagram of a first method of preparing a solar cell provided in an example of this application;

[0046] FIG5 is a schematic diagram of a second method of preparing a solar cell provided in an example of this application;

[0047] FIG6 is a cross-sectional schematic diagram of the second solar cell provided in the example of this application.

[0048] icon:

[0049] 100-battery substrate; 101-n-type monocrystalline silicon; 102-intrinsic amorphous silicon; 103-n-type amorphous silicon; 104-p-type amorphous silicon; 105-first transparent conductive film; 1051-first region; 1052-second region; 1053-first prefabricated film; 1054-second prefabricated film; 106-second transparent conductive film; 1061-third region; 1062-fourth region; 1063-third prefabricated film; 1064-fourth prefabricated film; 107-first gate line; 108-second gate line; 109-mask; 110-first surface; 120-second surface; L1-first thickness; L2-second thickness. DETAILED DESCRIPTION

[0050] 1 , a silicon heterojunction solar cell generally includes a silicon substrate, which is generally n-type single crystal silicon 101, intrinsic amorphous silicon 102 disposed on both sides of the n-type single crystal silicon 101, n-type amorphous silicon 103 and p-type amorphous silicon 104 disposed on the side of the intrinsic amorphous silicon 102 facing away from the n-type single crystal silicon 101, a first transparent conductive film 105 disposed on the n-type amorphous silicon 103, a second transparent conductive film 106 disposed on the side of the p-type amorphous silicon 104 facing away from the intrinsic amorphous silicon 102, a plurality of first gate lines 107 spaced apart on the first transparent conductive film 105, and a plurality of second gate lines 108 spaced apart on the side of the second transparent conductive film 106 facing away from the p-type amorphous silicon 104.

[0051] Silicon heterojunction solar cells boast high efficiency and high Voc. However, their lateral current transfer is poor, requiring the use of a transparent conductive film. Furthermore, the film must be able to collect incident light and reduce light reflectivity.

[0052] Currently, the common method for preparing the first transparent conductive film 105 and the second transparent conductive film 106 is to use an ITO target and deposit it onto the surface of a silicon wafer via PVD. PVD typically employs a plate-type deposition method, where a silicon wafer is placed on a carrier. Ar and O₂ are then introduced under low pressure. Accelerated by a magnetic field, the Ar gas molecules bombard the TCO target, sputtering the target molecules onto the surface of the silicon wafer, where they form a uniform film. In existing solar cells, the overall thickness of the transparent conductive film is generally uniform.

[0053] However, the current transmission performance of solar cells prepared by existing technologies is still poor, and the efficiency of solar cells needs to be further improved.

[0054] Therefore, the present application further improves the method for preparing solar cells, thereby improving the efficiency of solar cells to a certain extent. To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application.

[0055] The present application example provides a method for preparing a solar cell, wherein, referring to FIG. 2 , the solar cell includes a cell substrate 100 , a first transparent conductive film 105 and a first gate line 107 .

[0056] 2 , the cell substrate 100 includes n-type single crystal silicon 101 , intrinsic amorphous silicon 102 disposed on both sides of the n-type single crystal silicon 101 , and n-type amorphous silicon 103 and p-type amorphous silicon 104 disposed on the side of the intrinsic amorphous silicon 102 facing away from the n-type single crystal silicon 101 .

[0057] Continuing to refer to FIG3 , the method for preparing a solar cell includes:

[0058] S1. Preparation of the first transparent conductive film 105:

[0059] A first transparent conductive film 105 is deposited on the first surface 110 of the battery substrate 100 . The first transparent conductive film 105 has a plurality of first regions 1051 spaced apart from each other, and a second region 1052 outside the first region 1051 . A first thickness L1 of the first region 1051 is greater than a second thickness L2 of the second region 1052 .

[0060] A first transparent conductive film 105 having a first region 1051 and a second region 1052 is prepared, wherein the first thickness L1 of the first region 1051 is greater than the second thickness L2 of the second region 1052. Compared to conventional transparent conductive films having a total thickness of the second thickness L2, the transparent conductive film provided in the examples of this application has better conductivity. A transparent conductive film with better conductivity reduces the square resistance and improves the current collection efficiency of the solar cell.

[0061] The present application does not limit how to prepare the first transparent conductive film 105 having the first region 1051 and the second region 1052. In a possible embodiment, please continue to refer to FIG. 3 , a method for preparing a solar cell includes:

[0062] S101, preparation of the first transparent conductive film 105:

[0063] Referring to FIG. 4 , a first deposition is performed on the first surface 110 of the battery substrate 100 to form a first prefabricated film 1053 having a second thickness L2. A mask 109 is then applied to the surface of the first prefabricated film 1053 at a position corresponding to the second region 1052. A second deposition is then performed to form a second prefabricated film 1054 having a predetermined thickness at a position on the surface of the first prefabricated film 1053 not covered by the mask 109. The first prefabricated film 1053 and the second prefabricated film 1054 together form the first transparent conductive film 105.

[0064] The first transparent conductive film 105 prepared according to the preparation method of S101 is shown in FIG. 2 .

[0065] Alternatively, please continue to refer to FIG3 , the method for preparing a solar cell includes:

[0066] S102, preparation of the first transparent conductive film 105:

[0067] Referring to FIG. 5 , a mask 109 is applied to the first surface 110 of the battery substrate 100 at a location corresponding to the second region 1052 , and a first deposition is performed to form a first prefabricated thin film 1053 . Mask 109 is then removed, and a second deposition is performed to form a second prefabricated thin film 1054 . The first prefabricated thin film 1053 and the second prefabricated thin film 1054 together form the first transparent conductive film 105 .

[0068] The first transparent conductive film 105 prepared according to the preparation method of S101 is shown in FIG6 .

[0069] Furthermore, when depositing the first pre-film 1053 and the second pre-film 1054 , their target materials can be independently selected from at least one of ITO, IWO, and IZO.

[0070] For example, the target material for forming the first pre-film 1053 may be selected from ITO, and the target material for forming the second pre-film 1054 may be selected from IZO.

[0071] For example, the target material for forming the first pre-film 1053 may be selected from IZO, and the target material for forming the second pre-film 1054 may be selected from IWO.

[0072] Furthermore, the target material of the second region 1052 can be selected from a material with better light transmittance, and the target material of the first region 1051 can be selected from a material with better electrical conductivity.

[0073] Furthermore, the present application does not limit specific deposition parameters and specific values ​​of the first thickness L1 and the second thickness L2, and relevant personnel may make corresponding adjustments as needed.

[0074] For example, the first transparent conductive film 105 may be deposited under conditions of a power of 13.3-13.5 kW, an argon flow rate of 1200-1400 sccm, and an oxygen flow rate of 34 slm.

[0075] Exemplarily, the first transparent conductive film 105 includes a first region 1051 having a first thickness L1 of 100-630 nm, and a second region 1052 having a second thickness L2 of 90-130 nm.

[0076] For example, the first thickness L1 is 100 nm, and the second thickness L2 is 90 nm.

[0077] For example, the first thickness L1 is 300 nm, and the second thickness L2 is 100 nm.

[0078] For example, the first thickness L1 is 200 nm, and the second thickness L2 is 150 nm.

[0079] Furthermore, the present application does not limit the specific configuration of the mask 109 , and relevant personnel may make corresponding selections as needed.

[0080] In a possible embodiment, the mask 109 may be a hollow plate, wherein the hollow portion of the hollow plate is aligned with the thickened area to be exposed.

[0081] Alternatively, the mask 109 may be a photoresist. When preparing the first transparent conductive film 105 in accordance with S101, the photoresist may be applied to the surface of the first prefabricated film 1053, and then developed and exposed to form a groove corresponding to the first region 1051. Deposition is then continued within the groove to increase the thickness.

[0082] Alternatively, when preparing the first transparent conductive film 105 in the manner of S101, a photosensitive resin may be applied to the surface of the battery substrate 100, and then exposed and developed to form a groove corresponding to the first area 1051. A first deposition is performed in the groove to form the first prefabricated film 1053. The photosensitive resin is then removed, and a second deposition is performed on the surface of the first prefabricated film 1053 to form the second prefabricated film 1054.

[0083] Furthermore, the method for preparing the solar cell also includes preparing the second transparent conductive film 106 . The method for preparing the second transparent conductive film 106 can refer to the method for preparing the first transparent conductive film 105 .

[0084] Continuing to refer to FIG3 , the method for preparing a solar cell further includes:

[0085] S2. Preparation of the first gate line 107:

[0086] A first gate line 107 is formed in the first region 1051 .

[0087] The transparent conductive film has the characteristics that the thicker the film, the better the conductivity and the worse the light transmittance. Therefore, in the preparation method provided in the example of this application, the first gate line 107 is formed in the thickened first area 1051. On the first hand, thickening the first area 1051 can improve the conductivity of the first transparent conductive film 105 and improve the current transmission efficiency of the solar cell; on the second hand, thickening the first area 1051 will form the first gate line 107 above the first area 1051, and the first gate line 107 will block light. Therefore, even if the light transmittance of the thickened first area 1051 will deteriorate, it will not affect the light reception of the entire solar cell.

[0088] Furthermore, the present application does not limit how the first gate line 107 is formed, and relevant personnel may make corresponding choices as needed.

[0089] In a possible embodiment, the first gate line 107 may be formed on the first region 1051 by screen printing.

[0090] Exemplarily, silver paste is printed on the first area 1051 by screen printing, and then the silver paste is dried to form silver grid lines.

[0091] When the silver grid lines are formed by screen printing, the first transparent conductive film 105 can be prepared by the method of S102 .

[0092] Alternatively, in another possible embodiment, the first gate line 107 may be formed on the first region 1051 by electroplating.

[0093] For example, copper may be electroplated on the first region 1051 to form a copper grid line.

[0094] When copper gate lines are formed by copper electroplating, the first transparent conductive film 105 can be prepared in the manner of S101 , which can simplify the subsequent copper gate line preparation process.

[0095] Illustratively, a first deposition is performed on the first surface 110 of the battery substrate 100 to form a first prefabricated film 1053 of a second thickness L2; ​​a photosensitive resin is covered on the surface of the first prefabricated film 1053, and the photosensitive resin is exposed and developed to form a groove exposing the surface of the first prefabricated film 1053 corresponding to the first area 1051; a second deposition is performed in the groove to form a second prefabricated film 1054 of a preset thickness at a position on the surface of the first prefabricated film 1053 corresponding to the groove; the first prefabricated film 1053 and the second prefabricated film 1054 together form a first transparent conductive film 105; and then, copper grid lines are electroplated in the groove.

[0096] Furthermore, in order to improve the electroplating effect, a copper seed layer may be deposited on the surface of the second prefabricated film 1054 in the groove, and then copper gate lines may be electroplated on the copper seed layer in the groove.

[0097] Furthermore, the preparation method of the second grid line 108 of the solar cell can refer to the preparation method of the first grid line 107 .

[0098] The solar cell prepared by the above method is shown in Figures 2 and 6. The area corresponding to the grid line in the transparent conductive film is a thickened area, which can have good current transmission efficiency without reducing the light reception, thereby improving the efficiency of the solar cell.

[0099] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0100] Example 1

[0101] Example 1 provides a solar cell, the preparation method of which is as follows:

[0102] (1) Preparation of transparent conductive films

[0103] Using ITO as the target, a 90nm thick first pre-film 1053 was deposited on the first surface 110 of the battery substrate 100 at a power of 13.3 kW, an Ar flow rate of 1400 sccm, and an O2 flow rate of 34 slm. A mask was then placed over the first pre-film 1053. The mask had a hollow plate structure, and the hollowed portion of the hollow plate was aligned with the first region. Then, under the same deposition conditions, a 200nm thick second pre-film 1054 was deposited on the first pre-film 1053 at a position corresponding to the first region, forming a first transparent conductive film 105 with a thickness of 290nm in the first region 1051 and a thickness of 90nm in the second region 1052.

[0104] The refractive index of the first region 1051 is 2.0, and the refractive index of the second region 1052 is 1.95. The cell substrate 100 includes n-type monocrystalline silicon 101, intrinsic amorphous silicon 102 disposed on both sides of the n-type monocrystalline silicon 101, and n-type amorphous silicon 103 and p-type amorphous silicon 104 disposed on the sides of the two layers of intrinsic amorphous silicon 102 facing away from the n-type monocrystalline silicon 101.

[0105] Using ITO as a target, a 100 nm thick third pre-film 1063 was deposited on the second surface 120 of the battery substrate 100 at a power of 13.3 kW, an Ar flow rate of 1400 sccm, and an O2 flow rate of 34 slm. A mask was then placed over the third pre-film 1063. The mask had a hollow plate structure, and the hollowed portion of the hollow plate was aligned with the third region 1061. Then, under the same deposition conditions, a 200 nm thick fourth pre-film 1064 was deposited at the position of the third pre-film 1063 corresponding to the third region 1061, forming a second transparent conductive film 106 with a thickness of 300 nm in the third region 1061 and a thickness of 100 nm in the fourth region 1062.

[0106] The refractive index of the third region 1061 is 2.0, and the refractive index of the fourth region 1062 is 1.95.

[0107] (2) Preparation of gate lines

[0108] Silver grid lines are printed on the first region 1051 of the first transparent conductive film 105 and on the third region 1061 of the second transparent conductive film 106 , respectively.

[0109] Example 2

[0110] Example 2 provides a solar cell, which differs from Example 1 in that:

[0111] In step (1), a mask is formed on the first prefabricated film 1053. The mask is a photosensitive resin. The photosensitive resin is exposed and developed to form a first groove that exposes the surface of the first prefabricated film 1053 and corresponds to the first area 1051. Then, a second prefabricated film 1054 is deposited in the first groove.

[0112] A mask is formed on the third prefabricated film 1063. The mask is a photoresist. The photoresist is exposed and developed to form a second groove that exposes the surface of the third prefabricated film 1063 corresponding to the third area 1061. Then, a fourth prefabricated film 1064 is deposited in the second groove.

[0113] In step (2), copper grid lines are electroplated on the first region 1051 of the first transparent conductive film 105 in the first groove and on the third region 1061 of the second transparent conductive film 106 in the second groove.

[0114] Comparative Example 1

[0115] Comparative Example 1 provides a solar cell, which differs from Example 1 in that: in step (1), using ITO as a target material, at a power of 13.3 kw, an Ar flow rate of 1400 sccm and an O2 flow rate of 34 slm, a 90 nm first transparent conductive film 105 is deposited on the first surface 110 of the battery substrate 100; using ITO as a target material, at a power of 13.3 kw, an Ar flow rate of 1400 sccm and an O2 flow rate of 34 slm, a 100 nm second transparent conductive film 106 is deposited on the second surface 120 of the battery substrate 100.

[0116] Comparative Example 2

[0117] Comparative Example 2 provides a solar cell, which differs from Example 2 in that: in step (1), a 90nm first transparent conductive film 105 is deposited on the first surface 110 of the battery substrate 100; and a 100nm second transparent conductive film 106 is deposited on the second surface 120 of the battery substrate 100.

[0118] In step (2), a first copper seed layer is deposited on the first transparent conductive film 105, a photosensitive resin is covered on the first copper seed layer, and the photosensitive resin is exposed and developed to form a third groove on the surface of the first copper seed layer corresponding to the gate line, and a copper gate line is electroplated in the third groove.

[0119] A second copper seed layer is deposited on the second transparent conductive film 106, and a photosensitive resin is covered on the second copper seed layer. The photosensitive resin is exposed and developed to form a fourth groove that exposes the surface of the second copper seed layer corresponding to the gate line, and a copper gate line is electroplated in the fourth groove.

[0120] Test Case

[0121] The efficiency of the solar cells provided by Example 1, Example 2, Comparative Example 1 and Comparative Example 2 was tested, and the test results are shown in Table 1.

[0122] Table 1

[0123] Analysis of results: It can be seen from Table 1 that compared with Comparative Examples 1 and 2, the efficiency of the solar cells provided by Examples 1 and 2 of the present application is improved by 0.05%. The improvement in efficiency is mainly reflected in FF (fill factor), and the improvement in FF mainly comes from the reduction in Rs. That is, the TCO block is reduced at the grid line contact position, which is more conducive to the improvement of the overall Rs of the cell. At the same time, in terms of Isc (short-circuit current), the solar cells provided by the examples of the present application are not significantly affected, and the light collection rate is basically not significantly affected. The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A solar cell comprising: A battery substrate, a first transparent conductive film and a first grid line sequentially arranged on a first surface of the battery substrate; The first transparent conductive film has a plurality of first regions for arranging the first gate lines on a side facing away from the battery substrate, and a second region outside the first region; the first gate lines are arranged on the first regions; Along the thickness direction of the transparent conductive film, a first thickness of the first region is greater than a second thickness of the second region. 2 . The solar cell according to claim 1 , wherein the ratio of the first thickness to the second thickness does not exceed 10. 3 . 3 . The solar cell according to claim 2 , wherein the ratio of the first thickness to the second thickness does not exceed 7. 4 . The solar cell according to claim 2 , wherein the first thickness is 100 nm-630 nm, and the second thickness is 90 nm-130 nm.

5. The solar cell according to any one of claims 1 to 4, wherein the cell substrate has a second surface disposed opposite to the first surface, and the solar cell further comprises a second transparent conductive film and a second grid line disposed sequentially on the second surface; The second transparent conductive film has a third region for arranging the second gate lines on a side away from the battery substrate, and a fourth region outside the third region; the second gate lines are arranged in the third region; Along the thickness direction of the second transparent conductive film, the third thickness of the third region is greater than the fourth thickness of the fourth region. 6 . The solar cell according to claim 1 , wherein the cell substrate comprises a silicon substrate, an intrinsic amorphous silicon layer disposed on both surfaces of the silicon substrate, and a doped amorphous silicon layer disposed on the surface of the intrinsic amorphous silicon layer. 7 . The solar cell according to claim 1 , wherein a material of the first region is at least one selected from the group consisting of ITO, IWO and IZO. 8 . The solar cell according to claim 1 , wherein a material of the second region is at least one selected from the group consisting of ITO, IWO and IZO.

9. A method for preparing a solar cell, the solar cell comprising a cell substrate, a first transparent conductive film and a first grid line, the method comprising: Preparation of a first transparent conductive film: depositing a first transparent conductive film on a first surface of the battery substrate, wherein the first transparent conductive film has a plurality of first regions arranged at intervals, and a second region outside the first region; a first thickness of the first region is greater than a second thickness of the second region; Preparation of the first gate line: forming the first gate line on the first region. 10 . The preparation method according to claim 9 , wherein the ratio of the first thickness to the second thickness is no more than 10. The preparation method according to claim 10 , wherein the ratio of the first thickness to the second thickness is no more than 7. 12 . The preparation method according to claim 10 , wherein the first thickness is 100 nm-630 nm, and the second thickness is 90 nm-130 nm.

13. The preparation method according to any one of claims 9 to 12, further comprising: Preparation of the second transparent conductive film: depositing the second transparent conductive film on the second surface of the battery substrate, wherein the second transparent conductive film has a plurality of third regions for arranging the second grid lines and a fourth region outside the third region on a side away from the battery substrate, and a third thickness of the third region is greater than a fourth thickness of the fourth region; Preparation of the second gate line: the second gate line is arranged on the third area.

14. The preparation method according to any one of claims 9 to 13, wherein the battery substrate comprises a silicon substrate, an intrinsic amorphous silicon layer disposed on both surfaces of the silicon substrate, and a doped amorphous silicon layer disposed on the surface of the intrinsic amorphous silicon layer.

15. The preparation method according to any one of claims 9 to 14, wherein the method of depositing the first transparent conductive film on the first surface of the battery substrate comprises: A first deposition is performed on the first surface of the battery substrate to form a first Prefabricated films; A mask is covered at a position on the surface of the first prefabricated film corresponding to the second area, and then a second deposition is performed to form a second prefabricated film of a preset thickness at a position on the surface of the first prefabricated film not covered by the mask; the first prefabricated film and the second prefabricated film together form the first transparent conductive film.

16. The preparation method according to any one of claims 9 to 15, wherein the method of depositing the first transparent conductive film on the first surface of the battery substrate comprises: Covering a mask at a position corresponding to the second area on the first surface of the battery substrate, performing a first deposition, and forming a first prefabricated thin film; Then, the mask is removed and a second deposition is performed to form a second prefabricated film; the first prefabricated film and the second prefabricated film together form the first transparent conductive film. 17 . The preparation method according to claim 9 , wherein the material of the first prefabricated film and the second prefabricated film are independently selected from at least one of ITO, IWO, and IZO.

18. The preparation method according to any one of claims 9 to 17, wherein the method of covering the mask comprises: The hollow plate is placed on the surface to be deposited, and the hollow portion of the hollow plate is aligned with the first area.

19. The preparation method according to any one of claims 9 to 18, wherein the preparation of the first gate line comprises: The first gate line is formed in the first area by printing or electroplating. 20 . The manufacturing method according to claim 19 , wherein the first gate line is formed in the first region by electroplating. 21 . The preparation method according to claim 20 , wherein copper gate lines are formed in the first region by electroplating.

22. The preparation method according to claim 21, wherein the method of electroplating to form copper grid lines in the first region comprises: Performing a first deposition on the first surface of the battery substrate to form a first prefabricated thin film of the second thickness; Covering the surface of the first prefabricated film with a photosensitive adhesive, exposing and developing the photosensitive adhesive to form a groove exposing the surface of the first prefabricated film corresponding to the first area; A second deposition is performed in the groove to form a second prefabricated film of a preset thickness on the surface of the first prefabricated film corresponding to the position of the groove; the first prefabricated film and the second prefabricated film together form the first transparent conductive film; and copper grid lines are electroplated in the groove.

23. The preparation method according to claim 22, before electroplating the copper gate line in the groove, depositing a copper seed layer on the surface of the second prefabricated film in the groove, and electroplating the copper gate line on the copper seed layer.

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