A solar cell fine grid structure and preparation method thereof

Abstract

The present invention discloses a method for preparing a fine grid structure of a solar cell, comprising the following steps: S1 printing fine grid lines on the surface of a solar cell to obtain a first solar cell fine grid structure; S2 sending the solar cell sheet having the first solar cell fine grid structure to a sintering area for sintering, and performing electromagnetic treatment on the first solar cell fine grid structure in the rear section of the sintering area to obtain a second solar cell fine grid structure; S3 performing laser treatment on the second solar cell fine grid structure to obtain a finished product. Correspondingly, the present invention also discloses a solar cell fine grid structure prepared by the above preparation method. The preparation method provided by the present invention can narrow the fine grid width, increase the fine grid height, and improve the solar energy conversion efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of screen printing, and in particular to a solar cell fine grid structure and a preparation method thereof. Background Art

[0002] At present, screen printing is often used to print fine grids on solar cells. After the fine grids are printed, they are sintered. After sintering, the fine grid line width is generally 25-35μm. It is difficult to further reduce the line width by simply narrowing the design line width. This is because further reducing the design line width means further reducing the screen line width, which greatly increases the difficulty of printing and the risk of broken grids. At the same time, in order to save costs, the amount of silver paste used is reduced, which will also make it difficult to increase the line height. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing a thin grid structure of a solar cell, which can further reduce the thin grid width and increase the thin grid height.

[0004] The technical problem to be solved by the present invention is also to provide a solar cell fine grid structure having a suitable aspect ratio.

[0005] In order to solve the above technical problems, a method for preparing a thin grid structure of a solar cell is provided, comprising the following steps:

[0006] Printing fine grid lines on the surface of the solar cell to obtain a first solar cell fine grid structure;

[0007] Sending the solar cell sheet having the first solar cell fine grid structure to a sintering zone for sintering, and performing electromagnetic treatment on the first solar cell fine grid structure in the rear section of the sintering zone to obtain a second solar cell fine grid structure;

[0008] The second solar cell fine grid structure is laser processed to obtain a finished product.

[0009] Preferably, fine grid lines are printed on the surface of the solar cell by screen printing equipment, and the process parameters of the screen printing equipment are: screen spacing of 0.5 to 10 mm, scraper angle of 45 to 75°, and printing speed of 100 to 300 mm / s.

[0010] Preferably, the printing method of printing fine grid lines on the surface of the solar cell includes single printing or double printing.

[0011] Preferably, the temperature of the sintering zone is 100-1000° C., and the mesh belt speed is 300-600 cm / min.

[0012] Preferably, the electromagnetic treatment of the fine grid structure of the first solar cell is achieved by a planar electromagnetic device, and the planar electromagnetic device is arranged above the solar cell sheet at the end of the sintering zone.

[0013] Preferably, the vertical distance between the planar electromagnetic device and the solar cell is 20-25 cm, and the magnetic force of the planar electromagnetic device is 1-10N.

[0014] Preferably, the laser processing is completed by using a laser device, and the process parameters of the laser device are: laser power is 10 to 60 W, and laser speed is 1 to 50 m / s.

[0015] Preferably, the line width of the fine grid structure of the solar cell is ≤25 μm, and the reduction in line height shrinkage is ≥1 μm.

[0016] In order to solve the above problem, the present invention further provides a solar cell fine grid structure, which is manufactured by the above method for manufacturing the solar cell fine grid structure.

[0017] The implementation of the present invention has the following beneficial effects:

[0018] The method for preparing the fine grid structure of a solar cell described in the present invention, wherein electromagnetic treatment is added to the sintering area to reduce the shrinkage of the fine grid during solidification, thereby reducing the degree of collapse of the fine grid line height. By adding laser treatment after the electromagnetic treatment, the grid line width and the flatness of the grid line are modified to achieve the purpose of shrinking the line width. The present invention can further reduce the width of the fine grid and increase the height of the fine grid over the prior art, thereby enhancing the photocurrent and further improving the conversion efficiency of the solar cell. The line width of the fine grid structure of the solar cell prepared by the preparation method provided by the present invention is ≤25μm, and the reduction in line height shrinkage is ≥1μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a process flow chart of a method for preparing a fine grid structure of a solar cell according to the present invention. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0021] In order to solve the above technical problems, the present invention discloses a method for preparing a fine grid structure of a solar cell, such as Figure 1 As shown, the following steps are included:

[0022] S1, printing fine grid lines on the surface of a solar cell to obtain a first solar cell fine grid structure;

[0023] S2, sending the solar cell sheet having the first solar cell fine grid structure to a sintering zone for sintering, and performing electromagnetic treatment on the first solar cell fine grid structure in the rear section of the sintering zone to obtain a second solar cell fine grid structure;

[0024] S3, performing laser processing on the fine grid structure of the second solar cell to obtain a finished product.

[0025] The method for preparing the fine grid structure of a solar cell described in the present invention, wherein electromagnetic treatment is added to the sintering area to reduce the shrinkage of the fine grid during solidification, thereby reducing the degree of collapse of the fine grid line height. Laser treatment is added after the electromagnetic treatment to modify the grid line width and the flatness of the grid line to achieve the purpose of shrinking the line width. The present invention can further reduce the width of the fine grid and increase the height of the fine grid over the prior art, thereby enhancing the photocurrent and further improving the conversion efficiency of the solar cell.

[0026] The detailed description of each step in the above preparation method is as follows.

[0027] In the step S1, preferably, fine grid lines are printed on the surface of the solar cell by screen printing equipment.

[0028] The screen printing process requires relatively high quality of operators, requiring operators to have proficient experience in equipment use, especially in the printing process, the setting and adjustment of the print head are required to be high. Preferably, the process parameters of the screen printing equipment are: screen spacing of 0.5-10mm, scraper angle of 45-75°, and printing speed of 100-300mm / s.

[0029] It should be noted that there is a certain mutual influence between the printing speed and the viscosity of the ink. If the printing speed is greater than 300 mm / s, the deformation of the screen will increase, thereby reducing the size accuracy and position accuracy of the printed graphics; if the printing speed is less than 100 mm / s, the slurry will penetrate the edge of the printed graphics, causing the printed graphics to be too large or even jagged, seriously reducing the production quality.

[0030] In addition, during the screen printing process, since the screen printing plate itself has a certain surface tension, when the scraper returns ink, this tension will push the printing plate back, separating the printing plate from the ink, completing the ink leakage process. If the screen spacing is less than 0.5mm, the distance between the printing plate and the substrate surface is too small. After the scraper returns ink, the ink will not completely separate from the printing plate, causing graphic pollution, affecting the image quality and clarity, and in severe cases may cause damage to the printed product; if the screen spacing is greater than 10mm, a larger scraper pressure must be applied to complete printing, which may exceed the tolerable range of the screen surface tension, causing damage to the printing plate and seriously shortening the service life of the screen printing plate.

[0031] In order to meet the purpose of improving the aspect ratio of the grid lines and saving costs to the greatest extent, preferably, the printing method of printing fine grid lines on the surface of the solar cell includes single printing or secondary printing. The secondary printing and single printing each have advantages and disadvantages. Due to the two superpositions of the fine grid, the risk of grid breakage is smaller in the secondary printing, and the excellent aspect ratio of the fine grid lines after printing is easier to achieve, but it has high requirements on equipment and production line personnel, and the investment cost is high. The cost of a single printing is lower, but the height of the fine grid obtained is insufficient. The appropriate printing method can be selected according to the performance requirements of the solar cell.

[0032] Preferably, in step S2, the temperature of the sintering zone is 100-1000°C, and the mesh belt speed is 300-600 cm / min. The sintering zone can be set to multiple temperature intervals according to sintering requirements to form an ohmic contact of the metal semiconductor.

[0033] Preferably, the electromagnetic treatment of the first solar cell fine grid structure is achieved by a planar electromagnetic device, and the planar electromagnetic device is arranged above the solar cell sheet at the end of the sintering zone. The planar electromagnetic device applies an upward force to the molten silver, so that the fine grid shrinks less when solidifying, and reduces the collapse of the fine grid line height.

[0034] More preferably, the vertical distance between the planar electromagnetic device and the solar cell is 20-25 cm, and the magnetic force of the planar electromagnetic device is 1-10N.

[0035] It should be noted that in the prior art, no electromagnetic device is set in the sintering area of ​​the fine grid. The fine grid line width after sintering is generally 25-35μm. If you want to further reduce the fine grid width, you often use the method of narrowing the design line width. However, reducing the design line width means continuing to reduce the screen line width, which increases the difficulty of printing and also increases the risk of broken grids. Therefore, the present invention proposes to set a planar electromagnetic device at the end of the sintering area to give an upward force to the silver paste of the fine grid, so that the fine grid reduces the inertial contraction amount when solidifying and reduces the collapse of the fine grid line height.

[0036] The magnetic force of the planar electromagnetic device affects the final morphology of the fine grid. If the magnetic force of the planar electromagnetic device is too small, there will be almost no upward attraction to the molten silver paste, and it will not be able to prevent the line height from collapsing. On the contrary, if the magnetic force of the planar electromagnetic device is too large, the silver paste will be severely deformed and present a sharp triangular shape. In the subsequent processing, it will take a considerable amount of time to polish the shape. Moreover, the vertical distance between the planar electromagnetic device and the solar cell also determines the attraction of the planar electromagnetic device to the molten silver paste. Therefore, it is necessary to control the magnetic force of the planar electromagnetic device and the vertical distance between the planar electromagnetic device and the solar cell.

[0037] In step S3, the sintered fine grid lines are laser processed to modify the grid line width and the flatness of the grid line by laser to achieve the purpose of shrinking the line width. Preferably, the process parameters of the laser processing are: laser power of 10-60W, laser speed of 1-50m / s.

[0038] In addition, the laser processing process requires the laser equipment to have a strong dust removal capability, which can quickly remove the silver dust or other material dust generated during the processing. The laser equipment is equipped with a high-definition camera, which can determine the position coordinates of each fine grid and accurately take pictures of the fine grid edge for laser operation. The laser can adjust the power and focus to remove some edge fine grids.

[0039] Finally, by adding planar electromagnetic equipment and subsequent laser equipment to the rear section of the sintering zone of the sintering furnace, a solar cell fine grid structure with an excellent aspect ratio is obtained. Preferably, the line width of the solar cell fine grid structure is ≤25μm, and the reduction in line height shrinkage is ≥1μm.

[0040] Example 1

[0041] A method for preparing a thin grid structure of a solar cell

[0042] S1: printing fine grid lines on the surface of a solar cell to obtain a first solar cell fine grid structure.

[0043] Fine grid lines are printed on the surface of the solar cell by screen printing equipment, and the process parameters of the screen printing equipment are: screen spacing of 5 mm, scraper angle of 60°, and printing speed of 200 mm / s.

[0044] S2: sending the solar cell sheet having the first solar cell fine grid structure to a sintering zone for sintering, and performing electromagnetic treatment on the first solar cell fine grid structure in the rear section of the sintering zone to obtain a second solar cell fine grid structure;

[0045] The electromagnetic treatment of the fine grid structure of the first solar cell is achieved by a planar electromagnetic device, the planar electromagnetic device is arranged above the solar cell at the end of the sintering zone, the vertical distance between the planar electromagnetic device and the solar cell is 20cm, and the magnetic force of the planar electromagnetic device is 10N.

[0046] S3: performing laser processing on the fine grid structure of the second solar cell to obtain a finished product.

[0047] The process parameters of the laser treatment are: laser power is 40W, and laser speed is 30m / s.

[0048] Example 2

[0049] A method for preparing a thin grid structure of a solar cell

[0050] S1: printing fine grid lines on the surface of a solar cell to obtain a first solar cell fine grid structure.

[0051] Fine grid lines are printed on the surface of the solar cell by screen printing equipment, and the process parameters of the screen printing equipment are: screen spacing of 6 mm, scraper angle of 50°, and printing speed of 250 mm / s.

[0052] S2: sending the solar cell sheet having the first solar cell fine grid structure to a sintering zone for sintering, and performing electromagnetic treatment on the first solar cell fine grid structure in the rear section of the sintering zone to obtain a second solar cell fine grid structure;

[0053] The electromagnetic treatment of the fine grid structure of the first solar cell is achieved by a planar electromagnetic device, the planar electromagnetic device is arranged above the solar cell at the end of the sintering zone, the vertical distance between the planar electromagnetic device and the solar cell is 25 cm, and the magnetic force of the planar electromagnetic device is 7N.

[0054] S3: performing laser processing on the fine grid structure of the second solar cell to obtain a finished product.

[0055] The process parameters of the laser treatment are: laser power is 50W, and laser speed is 20m / s.

[0056] Comparative Example 1

[0057] A method for preparing a thin grid structure of a solar cell

[0058] S1: printing fine grid lines on the surface of a solar cell to obtain a first solar cell fine grid structure.

[0059] Fine grid lines are printed on the surface of the solar cell by screen printing equipment, and the process parameters of the screen printing equipment are: screen spacing of 5 mm, scraper angle of 60°, and printing speed of 200 mm / s.

[0060] S2: sending the solar cell sheet having the first solar cell fine grid structure to a sintering area for sintering.

[0061] Comparative Example 2

[0062] A method for preparing a thin grid structure of a solar cell

[0063] The difference from Example 1 is that the vertical distance between the planar electromagnetic device and the solar cell is 10 cm; and the magnetic force of the planar electromagnetic device is 20N.

[0064] The rest are the same as in Example 1.

[0065] Comparative Example 3

[0066] A method for preparing a thin grid structure of a solar cell

[0067] The difference from Example 1 is that the vertical distance between the planar electromagnetic device and the solar cell is 30 cm; and the magnetic force of the planar electromagnetic device is 0.9N.

[0068] The rest are the same as in Example 1.

[0069] The solar cell fine grid structures obtained in Examples 1 to 2 and Comparative Examples 1 to 3 were subjected to size tests, and the test results are shown in Table 1. From the data in Table 1, it can be seen that the solar cell fine grid structure prepared by the present invention has a narrow width, a high fine grid height, and a better aspect ratio.

[0070] Table 1 shows the test results of the fine grid structure of solar cells obtained in Examples 1 to 2 and Comparative Examples 1 to 3

[0071]

[0072]

[0073] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a thin grid structure of a solar cell, characterized in that: The following steps are involved: Printing fine grid lines on the surface of the solar cell to obtain a first solar cell fine grid structure; Sending the solar cell sheet having the first solar cell fine grid structure to a sintering zone for sintering, and performing electromagnetic treatment on the first solar cell fine grid structure in the rear section of the sintering zone to obtain a second solar cell fine grid structure; The second solar cell fine grid structure is laser processed to obtain a finished product.

2. The method for preparing a thin grid structure of a solar cell according to claim 1, characterized in that: Fine grid lines are printed on the surface of the solar cell by screen printing equipment, and the process parameters of the screen printing equipment are: screen spacing of 0.5-10 mm, scraper angle of 45-75 degrees, and printing speed of 100-300 mm / s.

3. The method for preparing a thin grid structure of a solar cell according to claim 2, characterized in that: The printing method for printing fine grid lines on the surface of the solar cell includes single printing or double printing.

4. The method for preparing a thin grid structure of a solar cell according to claim 1, characterized in that: The temperature of the sintering zone is 100-1000° C., and the mesh belt speed is 300-600 cm / min.

5. The method for preparing a thin grid structure of a solar cell according to claim 1, characterized in that: The electromagnetic treatment of the fine grid structure of the first solar cell is achieved by a planar electromagnetic device, and the planar electromagnetic device is arranged above the solar cell sheet at the end of the sintering zone.

6. The method for preparing a thin grid structure of a solar cell according to claim 5, characterized in that: The vertical distance between the planar electromagnetic device and the solar cell is 20-25 cm, and the magnetic force of the planar electromagnetic device is 1-10N.

7. The method for preparing a thin grid structure of a solar cell according to claim 1, characterized in that: The laser processing is completed by using a laser device, and the process parameters of the laser device are: laser power is 10~60 W, and laser speed is 1~50m / s.

8. The method for preparing a thin grid structure of a solar cell according to claim 1, characterized in that: The line width of the fine grid structure of the solar cell is ≤25 μm, and the reduction amount of line height shrinkage is ≥1 μm.

9. A solar cell fine grid structure, characterized in that: The solar cell fine grid structure is prepared by the preparation method of any one of claims 1 to 8.

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