Low-consumption silver solar cell and preparation method thereof

Abstract

The application relates to the technical field of solar cells, and discloses a preparation method of a low-silver-consumption solar cell piece, which comprises the following steps: S1, manufacturing a solar cell piece to be formed with grid lines; S2, after a mask plate is covered on the back light surface of the cell piece, a back metal fine grid line and an anti-oxidation conductive layer are deposited on the back light surface by adopting a physical vapor deposition mode; S3, a back main grid line is printed on the back light surface of the cell piece by using silver paste, and is solidified and shaped; S4, conductive paste is printed on the back metal fine grid line of the cell piece, and is solidified and shaped; and S5, a light-receiving surface grid line is arranged on the light-receiving surface of the cell piece. The application further discloses a low-silver-consumption solar cell piece which is manufactured by adopting the above preparation method. The application forms metal grid lines on the back of the cell by using a mask plate and combines with cheap conductive paste to replace low-temperature silver paste to print grid lines, so that the purpose of reducing silver consumption is achieved; and the method does not need to go through an etching process, so that the process flow can be shortened.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a low-silver-consumption solar cell and its preparation method. Background Technology

[0002] With the development of new energy sources, the photovoltaic industry, as a major force in new energy development, considers improving solar cell products a crucial research and development project. Currently, the grid lines of most high-efficiency solar cells are manufactured using silver paste printing. Silver, a major component of silver paste and a precious metal, contributes to the high cost of the grid lines. The silver paste consumption of heterojunction solar cells exceeds 200 mg / cell, accounting for over 60% of the non-silicon cost of solar cells. Furthermore, grid line uniformity is affected by various factors, such as temperature, humidity, and paste viscosity, all of which influence the grid line shape, and the desired grid line aspect ratio cannot be achieved in a single printing step. Therefore, reducing the amount of silver paste used or using other pastes or processes to replace silver paste is one of the main research directions for reducing the manufacturing cost of high-efficiency solar cells.

[0003] like Figure 6 As shown, to reduce the amount of silver paste used, the market typically employs a method of sequentially depositing a copper layer 2 and an anti-oxidation conductive layer 3 on the solar cell, followed by etching to remove the metal conductive film layer not covered by the back main grid lines and back fine grid lines. However, in actual production, the etching process takes a long time, and the back metal grid lines are formed during the etching process. Therefore, the printed conductive paste 4 cannot protect the sides of the metal grid lines, leading to excessive side corrosion; furthermore, etching has a negative impact on the solar cell. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-silver-consumption solar cell and its preparation method. The method utilizes a mask to form metal grid lines on the back of the cell and combines it with an inexpensive conductive paste to replace the low-temperature silver paste for printing the grid lines, thereby reducing silver consumption. Furthermore, the cell does not require an etching process, which can shorten the process flow and has the advantages of saving costs, improving efficiency, and protecting the environment.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention discloses a method for preparing a low-silver-consumption solar cell, comprising the following steps:

[0007] S1. Manufacturing solar cells to form grid lines, forming the first state of the solar cell.

[0008] S2. A mask is placed on the back surface of the first state body of the battery cell, and then a back metal grid line and an anti-oxidation conductive layer are deposited sequentially on the back surface of the first state body of the battery cell using physical vapor deposition in conjunction with the mask, to form the second state body of the battery cell.

[0009] S3, printing back main grid lines on the back of the second state body of the battery piece using silver paste, and curing and shaping to form a third state body of the battery piece.

[0010] S4, printing conductive paste on the back metal fine grid lines of the second state body or the third state body of the battery piece, and curing and shaping to form a fourth state body of the battery piece.

[0011] S5, setting light-receiving surface grid lines on the light-receiving surface of the first state body, the second state body, the third state body or the fourth state body of the battery piece.

[0012] Further, in the step S2, the back metal fine grid lines are copper grid lines, the height of the copper grid lines is between 50-500nm, the width is between 60-250μm, and the line spacing is between 120-800μm.

[0013] Further, in the step S2, the anti-oxidation conductive layer is a transparent conductive film, an oxide conductive film, a nickel film, a titanium film or an aluminum film, and the thickness is 5-50nm.

[0014] Further, in the step S3, the back main grid lines are provided with several lines with a thickness of 15-20μm and a spacing of 45-50mm, and after printing, the surface is dried at 170-190℃ for 10-12 minutes.

[0015] Further, in the step S4, the conductive paste is conductive aluminum paste, conductive carbon paste or conductive nickel paste; the width of the plurality of back fine grid lines printed on the back using conductive paste is 90-110μm, the thickness is 10-20μm, the spacing is 150-250μm, and the curing is performed at 150-180℃ for 40-50 minutes.

[0016] Further, in the step S5, the light-receiving surface grid lines are set on the light-receiving surface by printing several main grid lines with a width of 1.2-1.7mm, a thickness of 12-17μm and a spacing of 45-55mm, and several fine grid lines with a width of 45-55μm, a thickness of 8-12μm and a spacing of 0.8-1.2mm on the light-receiving surface using silver paste, and drying the surface at 175-180℃ for 10-15 minutes.

[0017] Further, in the S2 step, the mask material is stainless steel or other material with lower expansion coefficient and stable properties. The mask includes a flat plate with a smooth surface and closely adheres to the battery sheet, so that the grid line is more accurate in the sputtering process. The thickness of the flat plate is 1±0.1 mm, and a plurality of hollow grooves are arranged on the flat plate, the grooves correspond to the positions of the metal conductive fine grid lines; the edges of the flat plate are provided with a frame supporting the flat plate, and a chamfer is arranged at the frame, the width of the frame is 0.5-0.7 mm, and the chamfer is 1-3 mm.

[0018] The mask is detachably arranged on the battery sheet carrier. The mask is a separate individual, which is directly laid on the hollow part of the carrier during use, and does not need to be re-made. The separate individual is also more convenient to clean.

[0019] Further, the cross section of the groove is an inverted trapezoid, the top opening of the groove is between 120-500 μm, the bottom opening of the groove is between 60-250 μm, and the interval between adjacent grooves is between 120-800 μm. The groove adopts an inverted isosceles trapezoidal opening design to reduce the influence of edge effect.

[0020] Further, it further includes the step S6 of cleaning the mask: the mask should be cleaned after being plated for 150-250 times, and can be cleaned by using a sulfuric acid system or an ammonia water system to remove the copper layer and the protective layer on the surface of the mask.

[0021] The application also discloses a low-silver-consumption solar battery sheet prepared by the preparation method of the low-silver-consumption solar battery sheet. The battery sheet includes a battery sheet first state body to be formed with a grid line, a silver paste main grid line and a silver paste fine grid line are arranged on the light-receiving surface of the battery sheet first state body; a copper fine grid line and a silver paste main grid line are arranged on the back light-receiving surface; the copper fine grid line is provided with an anti-oxidation conductive layer; and the copper fine grid line and the anti-oxidation conductive layer are covered with conductive paste.

[0022] The application has the following advantages:

[0023] 1. The application forms a metal grid line on the back of the battery by physical vapor deposition using a mask, and replaces the low-temperature silver paste printed grid line with cheap conductive paste to reduce the consumption of silver; and the battery does not need to be etched, which not only saves manpower and material resources, but also prevents excessive corrosion of the grid line side, thereby reducing the series resistance of the solar battery sheet, improving the conversion efficiency, shortening the process flow, saving cost, improving efficiency and protecting the environment.

[0024] 2. The application forms a metal fine grid before the metal grid forming process, so that the metal fine grid can be completely wrapped up during printing and does not contact with air, thereby reducing the unqualified rate of the battery sheet caused by metal oxidation.

[0025] 3、The mask plate of the present application is a single individual, when used, directly laid on the hollow part of the carrier plate, used as installed, no need to re-produce the carrier plate, the single individual is also more convenient to clean. Meanwhile, the groove on the mask plate adopts the opening design of inverted isosceles trapezoid, reduces the influence of edge effect, and is convenient for deposition.

[0026] 4、The back fine grid line of the present application adopts the widened copper grid line, so that the series resistance of the battery piece is reduced, and the conversion efficiency of the battery piece is increased. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the preparation process flow chart of the present embodiment.

[0028] Figure 2 is the top view of the mask plate installed on the carrier plate in the present embodiment.

[0029] Figure 3 is the top view of the mask plate in the present embodiment.

[0030] Figure 4 is the combined schematic diagram of the mask plate and the solar cell piece in the present embodiment.

[0031] Figure 5 is the schematic diagram of the cross section of the grid line of the battery piece in the present embodiment.

[0032] Figure 6 is the cross section diagram of the grid line adopting the etching process in the background art.

[0033] Main component symbol explanation:

[0034] 1、The first state body of the battery piece;

[0035] 2、The copper layer;

[0036] 3、The anti-oxidation conductive layer;

[0037] 4、The conductive paste;

[0038] 5、The back metal fine grid line;

[0039] 6、The mask plate, 61、The groove;

[0040] 7、The carrier plate;

[0041] 8、The light-receiving surface grid line. DETAILED DESCRIPTION

[0042] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0043] As Figures 1 to 5As shown, the application discloses a preparation method of a low-consumption silver solar cell sheet, which comprises the following steps:

[0044] S1, manufacturing a solar cell sheet to be formed with a grid line, forming a first state body 1 of the cell sheet.

[0045] In this embodiment, the solar cell sheet is manufactured by using polycrystalline silicon material, both surfaces are polished and textured, an amorphous layer is deposited on both surfaces by CVD to form a PN junction, and a transparent conductive layer is deposited by a PVD device.

[0046] The first state body 1 of the cell sheet can have the following structure, but is not limited thereto. The first state body comprises, from top to bottom, a front transparent conductive layer, a front N-type doped layer, a front intrinsic layer, an N-type monocrystalline silicon sheet, a back intrinsic layer, a back P-type doped layer, and a back transparent conductive layer.

[0047] S2, depositing a back metal fine grid line 5 and an anti-oxidation conductive layer 3 on the back surface of the first state body 1 of the cell sheet by using a mask 6, and forming a second state body of the cell sheet.

[0048] (1) covering the mask 6 on the back surface of the first state body 1 of the cell sheet, and laying the metal mask 6 on the hollow part of a carrier plate 7 so that the metal mask 6 is closely attached to the cell sheet without any gap.

[0049] As shown in Figure 2 , Figure 3 , wherein the mask 6 comprises a plane plate, a plurality of hollow grooves 61 are arranged on the plane plate, the hollow grooves 61 correspond to the positions of the metal conductive fine grid lines, and the shape of the hollow grooves 61 is the same as that of the metal conductive fine grid lines. The thickness of the plane plate is 2 mm, the cross section of the hollow grooves 61 is inverted trapezoidal, the opening of the top of the hollow grooves 61 is 200 μm, the opening of the bottom of the hollow grooves 61 is 100 μm, and the adjacent hollow grooves 61 are spaced apart by 200 μm. During the deposition of the metal conductive film layer, the metal particles are deposited and blocked in the openings due to the small opening of the hollow grooves 61, so that the metal particles cannot be deposited on the cell sheet. The inverted trapezoidal opening design can reduce the influence of the edge effect and improve the deposition quality and cleaning cycle.

[0050] The four edges of the plane plate are provided with a frame for supporting the plane plate, and a chamfer is arranged at the frame. The width of the frame is 0.7 mm, and the chamfer is 1-3 mm. The mask 6 is a separate individual, which is directly laid on the hollow part of the carrier plate 7 in use, and is used immediately after being installed. The mask 6 does not need to be used to make a new carrier plate 7, and the separate individual is more convenient to clean.

[0051] The material of the mask 6 can be selected from 321 stainless steel, 410 stainless steel or other materials with lower expansion coefficient and stable properties, so as to meet different requirements of heat resistance and corrosion resistance.

[0052] (2) Depositing the back metal fine grid line 5 on the metal mask 6 by physical vapor deposition. In this embodiment, the back metal fine grid line 5 is a copper grid line. Specifically, the carrier plate 7 is sent into a PVD device, and a copper film is deposited on the metal mask 6 by target sputtering in a vacuum environment. Since there is the groove 61 structure on the mask 6, the copper film can only be deposited inside the groove 61, thereby forming a fine copper grid line on the back of the cell sheet. In this embodiment, the deposited copper grid line has a height of 300 nm.

[0053] (3) Depositing a layer of anti-oxidation conductive layer 3 on the copper layer 2 to form a second state body of the cell sheet. In this embodiment, the anti-oxidation conductive layer 3 is indium tin oxide (TIO) with a thickness of 10 nm.

[0054] PVD refers to a technology of depositing a thin film with certain special functions on the surface of a substrate under vacuum conditions by using low-voltage and large-current arc discharge technology, ionizing the evaporated material and gas by gas discharge, and accelerating the evaporated material and its reaction products to the workpiece by using an electric field.

[0055] S3. After taking out the carrier plate 7 from the PVD device, the metal mask 6 is removed and cleaned and dried. The back main grid line is printed on the back light surface of the second state body of the cell sheet using silver paste, and is cured and shaped to form a third state body of the cell sheet.

[0056] In this embodiment, three main grid lines with a width of 3 mm, a thickness of 20 μm, and a pitch of 50 mm are printed on the back light surface, and are surface dried at 180°C for 10 minutes.

[0057] S4. The conductive paste 4 is printed on the back metal fine grid line 5 of the second state body or the third state body of the cell sheet, and is cured and shaped to form a fourth state body.

[0058] In this embodiment, a plurality of fine grid lines with a width of 100 μm, a thickness of 15 μm, and a pitch of 200 μm are printed on the back using conductive carbon paste, and are cured at 180°C for 40 minutes.

[0059] S5. The light-receiving surface grid line 8 is arranged on the light-receiving surface of the first state body 1, the second state body, the third state body, or the fourth state body of the cell sheet.

[0060] Specifically, the main grid line and the fine grid line are printed on the light-receiving surface using silver paste, and are cured and shaped. In this embodiment, this step is arranged after forming the second state body, three main grid lines with a width of 1.5 mm, a thickness of 15 μm, and a pitch of 50 mm and a plurality of fine grid lines with a width of 50 μm, a thickness of 10 μm, and a pitch of 1 mm are printed on the light-receiving surface of the second state body, and are surface dried at 180°C for 10 minutes.

[0061] Thus, a low-consumption silver solar cell is prepared.

[0062] In order to improve the purity of the cell, the step S6 of cleaning the mask plate 6 is further added.

[0063] Specifically, the mask plate 6 should be cleaned after being plated for 150-250 times, and can be cleaned by using a sulfuric acid system or an ammonia system to remove the copper layer 2 and the protective layer on the surface of the mask plate 6.

[0064] The method of the present application can effectively form a low-cost, high-quality, high-efficiency and high-stability wide copper grid line on the back of a solar cell, and a new type of metal mask plate 6 is used to achieve precise, repeatable and clean mask effect.

[0065] In the present application, each parameter can be adjusted and optimized according to different requirements and conditions to achieve better results. For example:

[0066] The height of the copper grid line can be selected between 50-500nm to meet different conductivity and mechanical strength requirements;

[0067] The width of the copper grid line can be selected between 60-250μm to meet different light shielding and current collection efficiency requirements;

[0068] The pitch of the copper grid line can be selected between 120-800μm to meet different series resistance and fill factor requirements;

[0069] The anti-oxidation conductive layer 3 can be selected from materials such as transparent conductive film (TCO), oxide conductive film (OCO), nickel film (Ni), titanium film (Ti) or aluminum film (Al) to meet different anti-oxidation and reflection performance requirements; the thickness of the anti-oxidation conductive layer 3 can be selected between 5-50nm to meet different conductivity and reliability requirements;

[0070] The material of the metal mask plate 6 can be selected from 321 stainless steel, 410 stainless steel or other materials with lower expansion coefficient and stable properties to meet different heat resistance and corrosion resistance requirements;

[0071] The thickness of the metal mask plate 6 can be selected between 0.1-2mm to meet different stiffness and weight requirements;

[0072] The groove 61 structure of the metal mask plate 6 can be selected as an inverted isosceles trapezoidal or other shape to meet different deposition uniformity and precision requirements;

[0073] The groove 61 parameters of the metal mask plate 6 can be adjusted accordingly according to the parameters of the copper grid line to ensure that the shape and position of the copper grid line are consistent with the mask plate 6;

[0074] The conductive paste 4 can be selected from a conductive aluminum paste, a conductive carbon paste, a conductive nickel paste or other paste with conductive properties to meet different conductivity and cost requirements.

[0075] As shown in Figure 5 The application further discloses a low-silver-consumption solar cell sheet, which is prepared by the preparation method of the low-silver-consumption solar cell sheet. The cell sheet comprises a cell sheet first state body 1 to be formed into a grid line, a silver paste main grid line and a silver paste fine grid line are arranged on a light-receiving surface of the cell sheet first state body 1; a copper fine grid line and a silver paste main grid line are arranged on a back surface; an anti-oxidation conductive layer 3 is arranged on the copper fine grid line; and a conductive paste 4 is arranged on the periphery of the copper fine grid line and the anti-oxidation conductive layer 3. Compared with a market product prepared by electroplating etching, the metal fine grid line is formed before the metal grid forming process, so that the metal fine grid line can be completely wrapped when printing, and the metal fine grid line is not in contact with air, thereby reducing the unqualified rate of the cell sheet caused by metal oxidation.

[0076] In conclusion, the application forms a metal grid line on the back surface of a cell by using a mask and replaces a low-temperature silver paste to print a grid line by using a cheap conductive paste, so that the purpose of reducing silver consumption is achieved; and the method does not need to go through an etching process, so that the process flow can be shortened, and the method has the advantages of saving cost, improving efficiency, protecting the environment and the like.

[0077] The above merely describes the preferred embodiments of the application, but the protection scope of the application is not limited to this. Any changes or replacements within the technical scope disclosed by the application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the application.

Claims

1. A method for preparing a low-consumption silver solar cell, characterized in that: The method comprises the following steps: ​ S1, manufacturing a solar cell to be formed with a grid line, forming a first state body of the cell; S2, covering a mask on the back light surface of the first state body of the cell, then using physical vapor deposition method to deposit a back metal fine grid line and an anti-oxidation conductive layer on the back light surface of the first state body of the cell in sequence, forming a second state body of the cell, the back metal fine grid line is a copper grid line, and the anti-oxidation conductive layer is a transparent conductive film, an oxide conductive film, a nickel film, a titanium film or an aluminum film; S3, printing a back main grid line on the back light surface of the second state body of the cell using silver paste, and curing and shaping to form a third state body of the cell; S4, printing conductive paste on the back metal fine grid line of the second state body or the third state body of the cell, and curing and shaping to form a fourth state body of the cell, the conductive paste is conductive aluminum paste, conductive carbon paste or conductive nickel paste, the back metal fine grid line and the anti-oxidation conductive layer are covered with conductive paste, and the conductive paste completely wraps the back metal fine grid line; S5, setting a light receiving surface grid line on the light receiving surface of the first state body, the second state body, the third state body or the fourth state body of the cell.

2. The method for preparing a low-consumption silver solar cell sheet according to claim 1, characterized in that: In the step S2, the height of the copper grid line is between 50-500nm, the width is between 60-250μm, and the line spacing is between 120-800μm.

3. The method of claim 1, wherein the method further comprises: depositing a silver layer on the surface of the low-cost solar cell sheet; and annealing the silver layer at a temperature of 200-300°C for 10-30 minutes in a reducing atmosphere. In the step S2, the thickness of the anti-oxidation conductive layer is 5-50nm.

4. The method of claim 1, wherein the method further comprises: depositing a silver layer on the back surface of the thin film solar cell; and annealing the silver layer at a temperature of 200-300°C for 10-30 minutes in a reducing atmosphere. In the step S3, the back main grid line is provided with a plurality of lines with a thickness of 15-20μm and a spacing of 45-50mm, and after printing, the surface is dried at 170-190℃ for 10-12 minutes.

5. The method of claim 1, wherein the method further comprises: depositing a silver layer on the back surface of the solar cell; and annealing the silver layer at a temperature of 200-300°C for 10-30 minutes in a reducing atmosphere. In the step S4, the plurality of back fine grid lines printed on the back using conductive paste have a width of 90-110μm, a thickness of 10-20μm, and a spacing of 150-250μm, and are cured at 150-180℃ for 40-50 minutes.

6. The method of claim 1, wherein the method further comprises: depositing a silver layer on the back surface of the thin film solar cell; and annealing the silver layer at a temperature of 200-300°C for 10-30 minutes in a reducing atmosphere. In the step S5, the light receiving surface grid line is printed on the light receiving surface by silver paste, and has a width of 1.2-1.7mm, a thickness of 12-17μm, and a spacing of 45-55mm, and is surface dried at 175-180℃ for 10-15 minutes.

7. The method of claim 1, wherein the method further comprises: depositing a silver layer on the surface of the low-cost solar cell sheet. In the step S2, the mask material is stainless steel; the mask comprises a flat plate, the surface of the flat plate is flat and closely adheres to the cell; the thickness of the flat plate is 0.1-2mm, a plurality of hollow grooves are provided on the flat plate, the grooves correspond to the positions of the back metal fine grid lines, and the mask is detachably arranged on the cell carrier plate.

8. The method of claim 7, wherein the method further comprises: The cross section of the groove is an inverted trapezoid, the top opening of the groove is between 120-500μm, the bottom opening of the groove is between 60-250μm, and the spacing between adjacent grooves is between 120-800μm.

9. The method of claim 1, wherein the method further comprises: depositing a silver layer on the back surface of the thin film solar cell; and annealing the silver layer at a temperature of 200-300°C for 10-30 minutes in a reducing atmosphere. The method further comprises a step S6 of cleaning the mask plate: after 150-250 times of plating, the mask plate is cleaned by using a sulfuric acid system or an ammonia water system to remove the copper layer and the protective layer on the surface of the mask plate.

10. A low-loss silver solar cell, characterized in that: The low-consumption silver solar cell piece is prepared by using the preparation method of the low-consumption silver solar cell piece according to any one of claims 1 to 9; the cell piece comprises a cell piece first state body to be formed with a grid line, a silver paste main grid line and a silver paste fine grid line are arranged on a light-receiving surface of the cell piece first state body; a copper fine grid line and a silver paste main grid line are arranged on a back light-receiving surface; an anti-oxidation conductive layer is arranged on the copper fine grid line; and a conductive paste is arranged on the periphery of the copper fine grid line and the anti-oxidation conductive layer.

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