Solar cell, solar cell grabbing method and solar cell preparation method

Abstract

The invention discloses a solar cell, a solar cell grabbing method and a solar cell preparation method. The solar cell grabbing method comprises the following steps: S1, manufacturing a position identification pattern: engraving the position identification pattern in an area outside a main grid and an auxiliary grid on the back surface of the cell; s2, manufacturing a laser pattern: engraving the laser pattern in an area on the outer side of the main and auxiliary grids on the back surface of the battery, wherein a blank area exists between the laser pattern and the position identification pattern; and S3, grabbing point positioning: photographing the back surface of the battery by using a screen camera, and judging the position identification pattern through color difference caused by a blank area between the position identification pattern and the laser pattern. The method has the advantages that the problem of small color difference between the conventional position identification pattern and the laser processing area on the back of the battery is solved, the position identification pattern identification degree is improved through color difference comparison between the position identification pattern and the blank area, and the shooting capture success rate of the screen camera on the position identification pattern is improved, so that the error reporting probability of a printer is reduced; and the production efficiency is effectively improved.

Description

Technical Field

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

[0002] Topcon cells are generally considered to be the next generation of mainstream cell routes based on N-type silicon wafers. They have the advantages of ultra-high theoretical power generation efficiency and low upgrade cost compatible with PECR production lines, and have quickly replaced P-type cells. The current mainstream Topcon cell efficiency has reached 26.5%, and there is still a lot of room for improvement from the theoretical limit efficiency. How to quickly approach the theoretical efficiency is the primary research and development goal of major photovoltaic companies. Whoever can approach the theoretical limit can quickly grasp the N-type Topcon cell market and voice. To approach the theoretical limit, we must first analyze the efficiency loss of existing process cells. The efficiency loss of mass-produced Topcon cells mainly consists of three parts: composite loss / electrical loss / optical loss, and special optimization is carried out for different types of efficiency loss models. In response to the efficiency loss caused by the parasitic absorption of the back poly, a polyfinger cell has been developed, that is, poly only exists at the grid line position, and the poly is removed in the non-grid line area. This not only retains the passivation contact on the back of the Topcon cell, but also greatly reduces the parasitic absorption caused by the back poly. The process flow of polyfinger battery preparation is: 1 cleaning and texturing -- 2 boron doping -- 3 oxidation -- 4 alkaline polishing -- 5LP -- 6 phosphorus diffusion -- 7 laser -- 8 RCA cleaning -- 9 ALD -- 10 front and back film -- 11 metallization.

[0003] like Figure 3 As shown, the Topcon battery with polyfinger on the back has a difference between the grid line / non-grid line structure with poly and without poly, which leads to obvious color difference on the back of the battery after the silicon nitride film is prepared. Therefore, there is a problem in the battery manufacturing process: the color difference between the position identification pattern and the back substrate of the battery and the color difference between the position identification pattern and the grid line / non-grid line are close, which will interfere with the screen camera's grasping point and cause errors, resulting in failure to print. The working mechanism of the screen camera is to rely on the difference in contrast between the laser-processed and the surrounding non-laser-processed areas at the position identification pattern, and rely on pixel acquisition to determine the specific pattern for positioning. However, the color of the position identification pattern is close to the laser processing area. Under the same light source, it is difficult for the screen camera to identify the cross position mark. In the screen grasping point mode, if the position mark cannot be identified, the printer will report an error, thereby affecting production efficiency.

[0004] In view of this, it is necessary to provide a solar cell, a solar cell grasping method and a solar cell preparation method. Summary of the invention

[0005] The solar cell, solar cell grasping method and solar cell preparation method provided by the present invention effectively solve the problem that the back of the cell in the existing Polyfinger preparation route has significant color difference, resulting in a poor success rate of camera photography grasping.

[0006] The technical solution adopted by the present invention is: A solar cell point grasping method comprises the following steps: S1. Making position identification graphics: engraving position identification graphics on the area outside the main and auxiliary grids on the back of the battery.

[0007] S2, making a laser pattern: engraving a laser pattern on the area outside the main and auxiliary grids on the back side of the battery, and there is a blank area between the laser pattern and the position identification pattern.

[0008] S3, grasping point positioning: Use a screen camera to take a picture of the back of the battery, and judge the position recognition pattern to realize grasping point through the color difference caused by the blank area between the position recognition pattern and the laser pattern.

[0009] Furthermore, the laser scanning power of the position identification pattern is consistent with the laser scanning power of the laser pattern.

[0010] Furthermore, the laser scanning speed of the position identification pattern is equal to half of the laser scanning speed of the laser pattern.

[0011] Furthermore, the position identification pattern is a regular pattern or an irregular pattern.

[0012] Furthermore, the position identification graphic is in the shape of a cross.

[0013] Furthermore, the blank area is a regular shape or an irregular shape.

[0014] Furthermore, the position identification pattern and the blank area are both regular patterns, and the geometric center of the position identification pattern coincides with the geometric center of the blank area.

[0015] Furthermore, the ratio of the area of ​​the blank area to the area of ​​the position identification graphic is greater than 5.

[0016] Furthermore, the depth of the position identification pattern is greater than the depth of the laser pattern.

[0017] Furthermore, the area of ​​the blank area does not exceed one tenth of the back side of the battery.

[0018] A method for preparing a solar cell comprises the following steps: S1. Cleaning and velveting: remove various impurities on the surface of the substrate and prepare a pyramid velvet structure on the front side of the substrate.

[0019] S2. Boron doping: Boron doping is performed on the front side of the substrate.

[0020] S3, Oxidation: Boron atoms propel and grow BSG on the front side of the substrate.

[0021] S4, alkali polishing: alkaline cleaning and polishing of silicon wafers.

[0022] S5, LPVCD: Deposition of oxide layer and poly on the back side of the substrate.

[0023] S6, Phosphorus diffusion: Phosphorus doping is performed in the poly on the back side of the substrate.

[0024] S7, laser: making position identification pattern: engraving the position identification pattern on the area outside the main and auxiliary grids on the back of the battery; Making laser patterns: engraving laser patterns on the areas outside the main and auxiliary grids on the back of the battery, with a blank area between the laser patterns and the position identification patterns.

[0025] S8, RCA cleaning: remove the substrate front side plating and BPSG.

[0026] S9, ALD: depositing a layer of aluminum oxide on the surface of the substrate through the ALD process.

[0027] S10, front and back film: Silicon nitride film is coated on the front and back of the substrate.

[0028] S11. Metallization: Double-sided metallization forms a front metal grid line to collect current.

[0029] A solar cell is prepared by using the solar cell preparation method.

[0030] Compared with the prior art, the present invention has the following beneficial effects: By setting a blank area around the position identification pattern on the back of the battery, the problem of small color difference between the position identification pattern and the laser processing area on the back of the battery is changed. The recognition of the position identification pattern is improved by contrasting the color difference between the position identification pattern and the blank area, and the success rate of the screen camera capturing the position identification pattern is increased, thereby reducing the probability of error reporting by the printing machine and effectively improving production efficiency.

[0031] Both the position identification pattern and the blank area are regular patterns, and the geometric center of the position identification pattern coincides with the geometric center of the blank area, ensuring that the color difference of the position identification pattern in all directions is consistent when the silk screen camera captures the image, making it easy to quickly take pictures of the position identification pattern and improve the success rate of the position identification pattern being positioned by the silk screen camera.

[0032] The method of the present application does not require additional equipment or training models, but only requires changing the path of the laser in the original laser processing steps, which can significantly save costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A design diagram of the back side of a cell used in the solar cell gripping method provided in an embodiment of the present application.

[0034] Figure 2 A design diagram of the back side of a cell used in the prior art solar cell grasping method.

[0035] Figure 3 Schematic diagram of the back side of a solar cell after the silicon nitride film is prepared, as used in the prior art solar cell grasping method.

[0036] Figure 4 A schematic diagram of the back side of a cell after the silicon nitride film is prepared, which is applied to the solar cell gripping method provided in an embodiment of the present application.

[0037] The marks in the figure are: 1. Position identification graphic; 2. Blank area; 3. Laser graphic. DETAILED DESCRIPTION

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0039] like Figure 1 As shown, the first embodiment provided by the present application is a solar cell grasping method, comprising the following steps: S1. Making a position identification pattern: engraving a position identification pattern 1 on the area outside the main and auxiliary grids on the back of the battery.

[0040] S2, making a laser pattern: engraving a laser pattern 3 on the area outside the main and auxiliary grids on the back side of the battery, and there is a blank area 2 between the laser pattern 3 and the position identification pattern 1.

[0041] S3, grasping point positioning: Use a screen camera to take a picture of the back of the battery, and judge the position recognition pattern 1 to achieve the grasping point through the color difference caused by the blank area 2 between the position recognition pattern 1 and the laser pattern 3.

[0042] For ease of understanding, the blank area 2 refers to the area on the back of the battery that exists between the laser pattern 3 and the position identification pattern 1 and has not been laser processed. The capture point in this application is the capture of the position identification pattern 1 by an external camera.

[0043] In the above design, Figure 1 and Figure 2 By comparison, it can be seen that by leaving the area around the position identification pattern 1 blank without laser, a blank area 2 is formed on the substrate on the back of the battery, thereby increasing the color difference between the position identification pattern 1 and the extension of the substrate ( Figure 3and Figure 4 By comparison, it can be seen that the success rate of the screen camera in recognizing the position recognition pattern 1 is improved, thereby improving production efficiency.

[0044] Specifically, the laser scanning power of the position identification pattern 1 is consistent with the laser scanning power of the laser pattern 3 .

[0045] In the above design, the position identification pattern 1 and the laser pattern 3 are engraved by the same laser device, and the same power is used to ensure the consistency of the quality of the back of the battery.

[0046] Specifically: the laser scanning speed of the position identification pattern 1 is equal to half of the laser scanning speed of the laser pattern 3 .

[0047] In the above design, when the laser scanning speed of the position identification pattern 1 is half of the laser scanning speed of the laser pattern 3 , the laser scanning energy of the position identification pattern 1 is twice that of the laser pattern 3 , which can increase the engraving depth of the position identification pattern 1 .

[0048] Specifically: Figure 1 As shown, the position identification pattern 1 is a regular pattern or an irregular pattern. Regular patterns include rectangles, diamonds, triangles, ellipses, etc. For example, the position identification pattern is a cross.

[0049] In the above design, the position identification pattern 1 is set to a cross shape, and the cross-intersection feature can be used to facilitate the screen camera to capture points.

[0050] Specifically: Figure 1 As shown, the blank area 2 is a regular shape or an irregular shape. It can be a circle, a triangle, a rectangle or other shapes. For example, the blank area 2 is a square.

[0051] In the above design, the square blank area 2 is designed to facilitate setting of the laser path.

[0052] Specifically, the position identification pattern 1 and the blank area 2 are both regular patterns, and the geometric center of the position identification pattern 1 coincides with the geometric center of the blank area 2 .

[0053] In the above design, by setting the position identification pattern 1 at the geometric center of the blank area 2, it is ensured that the color difference of the position identification pattern 1 in all directions is consistent when the screen camera captures the image, so that the position identification pattern 1 can be quickly photographed and fixed.

[0054] Specifically: the ratio of the area of ​​the blank area 2 to the area of ​​the position identification pattern 1 is greater than 5.

[0055] In the above design, the ratio between the position identification pattern 1 and the blank area 2 is large enough to ensure that the color contrast between the position identification pattern 1 and the surrounding area is obvious, which makes it easier for the screen camera to effectively capture the position identification pattern 1.

[0056] Specifically: the depth of the position identification pattern 1 is greater than the depth of the laser pattern 3, which means that the distance that the position identification pattern 1 is recessed relative to the back side of the battery before step S1 is greater than the distance that the laser pattern 3 is recessed relative to the back side of the battery before step S1.

[0057] In the above design, the depth of the position identification pattern 1 is greater than the depth of the laser pattern 3, which can make the position identification pattern 1 more recognizable and more conducive to the positioning of the screen camera.

[0058] Specifically: the area of ​​the blank area 2 does not exceed one tenth of the back side of the battery.

[0059] In the above design, controlling the size of the blank area 2 can ensure that the recognition of the position identification pattern 1 is improved while ensuring normal processing of the back of the battery.

[0060] The second embodiment provided by the present application is a method for grasping points of solar cells, comprising the following steps: S1, engraving a position identification figure 1 on the remaining part after removing the main and auxiliary grids from the back of the battery; S2, engraving a laser figure 3 on the remaining part after removing the main and auxiliary grids from the back of the battery, and there is a blank area 2 between the laser figure 3 and the position identification figure 1; S3, grasping and locating the position identification figure 1 using a screen camera. The laser scanning power of the position identification figure 1 is consistent with the laser scanning power of the laser figure 3. The laser scanning speed of the position identification figure 1 is equal to half of the laser scanning speed of the laser figure 3. The position identification figure 1 is a cross. The blank area 2 is a square. The position identification figure 1 and the blank area 2 are both regular figures, and the geometric center of the position identification figure 1 coincides with the geometric center of the blank area 2. The ratio of the area of ​​the blank area 2 to the area of ​​the position identification figure 1 is greater than 5. The depth of the position identification figure 1 is greater than the depth of the laser figure 3. The area of ​​the blank area 2 does not exceed one tenth of the back of the battery.

[0061] In the above design, the area around the position identification pattern 1 is left blank by not lasering, thereby forming a blank area 2, thereby increasing the color difference between the position identification pattern 1 and the extension of the substrate, improving the success rate of the screen camera to recognize the position identification pattern 1, and thus improving production efficiency. The same power is used to ensure the consistency of the quality of the back of the battery. When the laser scanning speed of the position identification pattern 1 is half of the laser scanning speed of the laser pattern 3, the laser scanning energy of the position identification pattern 1 is twice that of the laser pattern 3, which can increase the depth of the engraving of the position identification pattern 1. The position identification pattern 1 is set to a cross shape, and the cross intersection feature can be used to facilitate the screen camera to capture points. The square blank area 2 design can facilitate the setting of the laser path. By coinciding the geometric center of the regular pattern position identification pattern 1 with the geometric center of the regular pattern blank area 2, it can be ensured that the color difference of the position identification pattern 1 in all directions is consistent when the screen camera captures, which is convenient for quickly taking pictures of the position identification pattern 1. The ratio between the position identification pattern 1 and the blank area 2 is large enough to ensure that the color contrast between the position identification pattern 1 and the surrounding is obvious, which is convenient for the screen camera to effectively capture the position identification pattern 1. Controlling the size of the blank area 2 can ensure that the recognition of the position identification pattern 1 is improved while ensuring normal processing of the back of the battery.

[0062] The third embodiment provided by the present application is a method for grasping points of solar cells, comprising the following steps: S1, engraving a position identification figure 1 on the remaining part after removing the main and auxiliary grids from the back of the battery; S2, engraving a laser figure 3 on the remaining part after removing the main and auxiliary grids from the back of the battery, and there is a blank area 2 between the laser figure 3 and the position identification figure 1; S3, grasping and locating the position identification figure 1 using a silk screen camera. The laser scanning power of the position identification figure 1 is consistent with the laser scanning power of the laser figure 3. The laser scanning speed of the position identification figure 1 is equal to half of the laser scanning speed of the laser figure 3. The blank area 2 is a square with a side length of 5 mm. The geometric center of the position identification figure 1 coincides with the geometric center of the blank area 2.

[0063] The fourth embodiment provided in the present application is a method for grasping points of solar cells, comprising the following steps: S1, engraving a position identification graphic 1 on the remaining portion after removing the main and auxiliary grids from the back of the battery; S2, engraving a laser graphic 3 on the remaining portion after removing the main and auxiliary grids from the back of the battery, and there is a blank area 2 between the laser graphic 3 and the position identification graphic 1; S3, grasping and locating the position identification graphic 1 using a silk screen camera. The laser scanning power of the position identification graphic 1 is consistent with the laser scanning power of the laser graphic 3. The laser scanning speed of the position identification graphic 1 is equal to half of the laser scanning speed of the laser graphic 3. The blank area 2 is a square with a side length of 7 mm. The position identification graphic 1 is located at the center of the blank area 2. This application has been subjected to a control test, and the control test uses the third embodiment, the fourth embodiment and the comparative example. The success rate of grasping points by taking pictures with a silk screen camera is shown in Table 1 below.

[0064] Table 1

[0065] The data source of the grasping point success rate of the third embodiment in Table 1 is: 10,000 batteries with a 5 mm square blank area were photographed and positioned using a screen camera, of which 9,512 batteries were successfully captured and positioned by the screen camera. The grasping point success rate of the third embodiment is .

[0066] The data source of the grasping point success rate of the fourth embodiment in Table 1 is: 10,000 batteries with a 7mm square blank area were photographed and positioned using a screen camera, of which 9,574 batteries were successfully captured and positioned by the screen camera. The grasping point success rate of the fourth embodiment is .

[0067] The data source of the grasping point success rate of the comparative example in Table 1 is: 10,000 batteries without blank areas were photographed and positioned using a screen camera, of which 7,680 batteries were successfully captured and positioned by the screen camera. The grasping point success rate of the comparative example is .

[0068] It can be seen from Table 1 above that the capture success rates of the third embodiment and the fourth embodiment are both greater than those of the comparative example, wherein the success rate of the third embodiment is increased by 18.32% on the basis of the comparative example, and the success rate of the fourth embodiment is increased by 18.94% on the basis of the comparative example, which can greatly improve the success rate of the screen camera in capturing the position recognition pattern 1, thereby reducing the number of errors reported by the printing press and effectively improving work efficiency.

[0069] The present application has been subjected to a control test, and the electrical performance of the third embodiment, the fourth embodiment and the comparative example are compared as shown in Table 2 below.

[0070] Table 2 Uoc Isc FF Eta Third embodiment 0.07319 14.0755 84.2418 25.9279 Fourth embodiment 0.07323 14.0632 84.2604 25.9271 Comparative Example 0.07321 14.0715 84.2475 25.9296

[0071] In Table 2, Uoc represents the voltage across the solar cell without external load. Isc represents the current flowing through the solar cell when the two ends of the solar cell are short-circuited. FF represents the difference between the maximum power point of the solar cell and the maximum power point under ideal conditions. The higher the FF, the better the electrical performance of the solar cell. Eta represents the battery conversion rate.

[0072] The test method of the test data of the third embodiment in Table 2 is: under dark room conditions, the battery with a square blank area 2 with a side length of 5 mm obtained in the third embodiment is tested by an IV tester, so that the battery is pressed into contact with the probe of the IV tester, and the battery is irradiated with standard sunlight, and the Uoc value, Isc value, FF value and Eta value of the battery are measured by the IV tester.

[0073] The test method of the test data of the fourth embodiment in Table 2 is: under dark room conditions, the battery with the square blank area 2 with a side length of 7 mm obtained in the third embodiment is tested by an IV tester, so that the battery is pressed into contact with the probe of the IV tester, and the battery is irradiated with standard sunlight, and the Uoc value, Isc value, FF value and Eta value of the battery are measured by the IV tester.

[0074] The test method for the comparative test data in Table 2 is: under dark room conditions, the battery without the blank area 2 obtained in the third embodiment is tested by an IV tester, so that the battery is pressed into contact with the probe of the IV tester, and the battery is irradiated with standard sunlight, and the Uoc value, Isc value, FF value and Eta value of the battery are measured by the IV tester.

[0075] It can be seen from Table 2 above that after the present application sets a blank area 2 around the position identification graphic 1, the difference between the third embodiment Uoc and the fourth embodiment relative to the comparison ratio is -0.0002 and 0.0002, respectively. The difference between the third embodiment Isc and the fourth embodiment Isc relative to the comparison ratio is 0.0040 and -0.0083, respectively. The difference between the third embodiment FF and the fourth embodiment FF relative to the comparison ratio is -0.0057 and 0.0129, respectively. The difference between the second embodiment Eta and the fourth embodiment Eta relative to the comparison ratio is -0.0017 and -0.0025, respectively. The influence of the data differences on the actual battery parameters is negligible.

[0076] Based on Table 1 and Table 2, it can be concluded that the adverse effect of the third embodiment on the battery electrical performance is negligible compared with the fourth embodiment. However, the success rate of the battery processed by the third embodiment in the comparative example is significantly improved compared with the fourth embodiment. The success rate of the third embodiment is increased by 18.32% on the basis of the comparative example, and the success rate of the fourth embodiment is increased by 18.94% on the basis of the comparative example. The success rate of the screen camera in capturing the position recognition pattern 1 can be greatly improved, thereby reducing the number of errors reported by the printing press and effectively improving work efficiency.

[0077] The present application also provides a fifth embodiment, which is a method for preparing a solar cell, comprising the following steps: S1. Cleaning and velveting: remove various impurities on the surface of the substrate and prepare a pyramid velvet structure on the front side of the substrate.

[0078] S2. Boron doping: Boron doping is performed on the front side of the substrate.

[0079] S3, Oxidation: Boron atoms propel and grow BSG on the front side of the substrate.

[0080] S4, alkali polishing: alkaline cleaning and polishing of silicon wafers.

[0081] S5, LPVCD: Deposition of oxide layer and poly on the back side of the substrate.

[0082] S6, Phosphorus diffusion: Phosphorus doping is performed in the poly on the back side of the substrate.

[0083] S7, laser: making position identification pattern: engraving position identification pattern 1 on the area outside the main and auxiliary grids on the back of the battery; Making a laser pattern: engraving a laser pattern 3 on the area outside the main and auxiliary grids on the back of the battery, and there is a blank area 2 between the laser pattern 3 and the position identification pattern 1.

[0084] S8, RCA cleaning: remove the substrate front side plating and BPSG.

[0085] S9, ALD: depositing a layer of aluminum oxide on the surface of the substrate through the ALD process.

[0086] S10, front and back film: Silicon nitride film is coated on the front and back of the substrate.

[0087] S11. Metallization: Double-sided metallization forms a front metal grid line to collect current. Double-sided refers to the front side and the back side of the substrate.

[0088] The present application also provides a sixth embodiment. The fifth embodiment is a solar cell prepared by the method in the fifth embodiment.

[0089] To further explain in detail, it should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A solar cell point grabbing method, characterized in that: The steps include: S1. Making a position identification pattern: engraving a position identification pattern (1) on the area outside the main and auxiliary grids on the back of the battery; S2, making a laser pattern: engraving a laser pattern (3) on the area outside the main and auxiliary grids on the back of the battery, with a blank area (2) between the laser pattern (3) and the position identification pattern (1); S3, grasping point positioning: Use a screen camera to take a picture of the back of the battery, and determine the grasping point of the position identification pattern (1) based on the color difference caused by the blank area (2) between the position identification pattern (1) and the laser pattern (3).

2. The solar cell grasping method according to claim 1, characterized in that: The laser scanning power of the position identification pattern (1) is consistent with the laser scanning power of the laser pattern (3).

3. The solar cell grasping method according to claim 1, characterized in that: The laser scanning speed of the position identification pattern (1) is equal to half the laser scanning speed of the laser pattern (3).

4. The solar cell grasping method according to claim 1, characterized in that: The position identification pattern (1) is a regular pattern or an irregular pattern.

5. The solar cell grasping method according to claim 4, characterized in that: The position identification pattern (1) is in the shape of a cross.

6. The solar cell grasping method according to claim 1, characterized in that: The blank area (2) is a regular shape or an irregular shape.

7. The solar cell grasping method according to claim 1, characterized in that: The position identification pattern (1) and the blank area (2) are both regular patterns, and the geometric center of the position identification pattern (1) coincides with the geometric center of the blank area (2).

8. The solar cell grasping method according to claim 1, characterized in that: The ratio of the area of ​​the blank area (2) to the area of ​​the position identification pattern (1) is greater than 5.

9. The solar cell grasping method according to claim 1, characterized in that: The depth of the position identification pattern (1) is greater than the depth of the laser pattern (3).

10. The solar cell grasping method according to claim 1, characterized in that: The area of ​​the blank area (2) does not exceed one tenth of the back side of the battery.

11. A method for preparing a solar cell, characterized in that: The steps include: S1. Cleaning and velveting: remove various impurities on the surface of the substrate and prepare a pyramid velvet structure on the front side of the substrate; S2, Boron doping: Boron doping is performed on the front side of the substrate; S3, oxidation: Boron atoms propel forward and grow BSG on the front side of the substrate; S4, alkali polishing: alkali cleaning and polishing of silicon wafers; S5, LPVCD: deposit oxide layer and poly on the back side of the substrate; S6, Phosphorus diffusion: Phosphorus doping is performed in the poly on the back side of the substrate; S7, laser: making position identification pattern: engraving the position identification pattern (1) on the area outside the main and auxiliary grids on the back of the battery; Making a laser pattern: engraving a laser pattern (3) on the area outside the main and auxiliary grids on the back of the battery, with a blank area (2) between the laser pattern (3) and the position identification pattern (1); S8, RCA cleaning: remove the substrate front side plating and BPSG; S9, ALD: depositing a layer of aluminum oxide on the surface of the substrate by an ALD process; S10, front and back film: silicon nitride film is coated on the front and back of the substrate; S11. Metallization: Double-sided metallization forms a front metal grid line to collect current.

12. A solar cell, characterized in that: The solar cell is prepared by the method for preparing the solar cell according to claim 11.

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