A method for reducing leakage current of TOPCon solar cells after cutting

Abstract

The present invention provides a method for reducing leakage current of TOPCon solar cells after cutting, and relates to the technical field of TOPCon solar cells. The method for reducing leakage current of TOPCon solar cells after cutting of the present invention comprises the following steps: cutting the cell piece by laser cutting; laminating and pressing the cut cell strips; passivating the edges of the laminated and pressed cell strips by atomic deposition; and annealing and thermally repairing the passivated cell strips to obtain repaired cell strips. The present invention adopts the ALD double process to plate AlO on the cut surface of the Topcon solar cell. x The passivation layer ensures process efficiency while passivating exposed dangling bonds, increasing the parallel resistance of the battery and thus reducing edge leakage current.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of TOPCon solar cells, and in particular to a method for reducing leakage current of a TOPCon solar cell after cutting. Background Art

[0002] The current of a solar cell is proportional to the cell area. Large-sized cells are inevitably accompanied by large currents. After the cells are packaged in series to form a module, the power loss is proportional to the square of the current. In order to reduce the power loss caused by the current, the finished cell (the whole cell) can be divided into at least two slices. At present, Topcon solar cells need to be laser cut in the process of preparing them into modules. The cut cell strips are then connected to the positive and negative poles of the welding ribbon to form a cell string. The cell string is processed to form a battery module. During the laser cutting process, a certain degree of thermal shock damage will be caused to the cell, and the cracking process after dicing will cause additional mechanical damage, which will lead to an increase in leakage current. In addition, the cross-section of the laser-cut cell has no surface passivation and serious edge recombination, resulting in a serious loss of conversion efficiency.

[0003] In the existing technology, after laser non-destructive cutting of Topcon solar cells, the cut edges are not subjected to any passivation process, and the cut cell strips are directly processed in series. Although the non-destructive cutting process is significantly optimized compared to the previous lossy cutting process, it still produces a large number of dangling bonds, which inevitably lead to the existence of leakage current. The leakage current at the edges of the cell is relatively high. For Topcon solar cells, the leakage current damage caused by non-destructive cutting reaches 0.02A to 0.04A per cut, affecting the overall power generation performance of the subsequent components. In other words, the existing Topcon solar cells experience leakage current at the cut edges after laser non-destructive cutting. The leakage current at the cell edges is relatively high, and the existing process does not protect the cut edges, resulting in a large leakage current.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The present invention aims to provide a method for reducing leakage current of TOPCon solar cells after cutting. The present invention adopts the method of depositing an AlOx passivation layer on the cut surface of the TopCon solar cell using an ALD double process to reduce leakage current at the cut edge of the cell.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0007] In a first aspect, the present invention provides a method for reducing leakage current of a TOPCon solar cell after cutting, the method comprising the following steps:

[0008] The battery cells are cut by laser cutting;

[0009] The cut battery strips are stacked and pressurized;

[0010] The edges of the stacked and pressed battery strips are passivated using atomic deposition.

[0011] The passivated battery bar is subjected to annealing and thermal repair treatment to obtain a repaired battery bar.

[0012] In the present invention, first, the whole cell is cut by laser non-destructive cutting to obtain a cell strip with smooth cutting edges, which reduces the thermal effect and ensures that the cutting seam is smooth and without thermal damage, thereby further ensuring the subsequent atomic deposition (ALD) AlO plating. x Secondly, the present invention applies pressure to the stacking process of the cut battery strips. This is because the ALD deposition method has serious winding plating. The stacking and pressurizing process before coating can avoid the formation of negatively charged AlO on the N side of the Topcon solar cell. x The passivation layer, on the one hand, allows electrons to be smoothly extracted from the negative electrode, and on the other hand, ensures the welding tension between the component end welding ribbon and the pad point. Third, the present invention adopts the atomic deposition (ALD) method to passivate the edges of the laminated battery strips, ensuring process efficiency while passivating the exposed dangling bonds, thereby reducing edge leakage current. Fourth, the present invention anneals the coated battery cells. High-temperature annealing can increase the overall lattice thermal motion of the silicon crystal, repair the interface defects between the coating and the silicon crystal, and reduce edge leakage current.

[0013] Preferably, the laser cutting uses infrared laser.

[0014] Preferably, the power of the infrared laser is 5 to 50 W, for example, it can be 5 W, 6 W, 8 W, 10 W, 12 W, 14 W, 16 W, 18 W, 20 W, 25 W, 30 W, 35 W, 40 W, 45 W, 50 W, etc.

[0015] Preferably, the temperature of the laser cutting is 150-250°C, for example, it can be 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, etc.

[0016] In the present invention, the whole cell is cut by laser non-destructive cutting. A low-power (5-50W) infrared laser is used and the laser cutting is completed at 150-250°C to reduce the thermal effect, ensure the kerf is smooth and without thermal damage, ensure the uniformity of the ALD coating, better passivate the dangling bonds, and reduce the occurrence of leakage current. The coolant used is deionized water, which can avoid the charged particles from combining with the dangling bonds at the cutting edge and affecting the subsequent AlO x Passivation effect of the passivation layer.

[0017] Preferably, the laser cutting groove length at both ends of the battery cell is 0 to 3 mm, for example, it can be 0.001 mm, 0.005 mm, 0.01 mm, 0.05 mm, 0.1 mm, 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm, etc.

[0018] Preferably, in the lamination and pressurization process, the number of stacked battery strips is ≥2, for example, it can be 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.

[0019] Preferably, in the lamination pressurization treatment, the pressurization pressure is ≥1N, for example, it can be 1N, 1.2N, 1.5N, 1.8N, 2N, 2.2N, 2.5N, 3N, 3.5N, 4N, 4.5N, 5N, etc.

[0020] Preferably, the atomic deposition is specifically to deposit AlO on the edge of the battery strip. x passivation layer.

[0021] Preferably, the AlO x The thickness of the passivation layer is 4 to 60 nm, for example, it can be 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, 52 nm, 54 nm, 56 nm, 58 nm, 60 nm, etc.

[0022] Preferably, the AlO x The passivation layer is prepared by the following steps:

[0023] (a) After the laminated and pressurized battery strips are placed in an atomic deposition device, the chamber is evacuated, and ozone and trimethylaluminum are alternately introduced for deposition, followed by nitrogen purge.

[0024] (b) The chamber is evacuated, water vapor and trimethylaluminum are alternately introduced for deposition, and then purged with nitrogen.

[0025] In the present invention, ALD is used to perform a dual-process coating treatment on the cut edge. First, a film is formed using ozone and TMA. This film has the characteristics of strong adhesion and scratch resistance, which can ensure the mechanical properties of the film. Then, a film is formed using water and TMA. This film has a fast formation rate, which can ensure process efficiency while passivating the exposed dangling bonds, increasing the parallel resistance of the battery, and thus reducing edge leakage current.

[0026] Preferably, in step (a), the introduction ratio of ozone and trimethylaluminum is 1:(15-35), for example, 1:15, 1:16, 1:18, 1:20, 1:22, 1:24, 1:26, 1:28, 1:30, 1:32, 1:34, 1:35, etc.

[0027] Preferably, in step (a), the flow rate of ozone is 200 to 600 sccm, for example, 200 sccm, 250 sccm, 300 sccm, 350 sccm, 400 sccm, 450 sccm, 500 sccm, 550 sccm, 600 sccm, etc.

[0028] Preferably, in step (a), the flow rate of trimethylaluminum is 5000-15000sccm, for example, it can be 5000sccm, 6000sccm, 6500sccm, 7000sccm, 7500sccm, 8000sccm, 8500sccm, 9000sccm, 9500sccm, 10000sccm, 11000sccm, 12000sccm, 13000sccm, 14000sccm, 15000sccm, etc.

[0029] Preferably, in step (a), the deposition temperature is 150-200°C, for example, it can be 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, etc., and the deposition pressure is 400-800Torr, for example, it can be 400Torr, 450Torr, 500Torr, 550Torr, 600Torr, 650Torr, 700Torr, 750Torr, 800Torr, etc.

[0030] Preferably, in step (a), the alternating cycle number is 20 to 300 times, for example, it can be 20 times, 40 times, 60 times, 80 times, 100 times, 120 times, 140 times, 160 times, 180 times, 200 times, 220 times, 240 times, 260 times, 280 times, 300 times, etc.

[0031] Preferably, in step (a), the nitrogen purge gas flow rate is 5000-15000sccm, for example, it can be 5000sccm, 6000sccm, 6500sccm, 7000sccm, 7500sccm, 8000sccm, 8500sccm, 9000sccm, 9500sccm, 10000sccm, 11000sccm, 12000sccm, 13000sccm, 14000sccm, 15000sccm, etc.

[0032] Preferably, in step (b), the introduction ratio of water vapor and trimethylaluminum is (1-2):(2-1), for example, it can be 1:2, 1.1:1.9, 1.2:1.8, 1.3:1.7, 1.4:1.6, 1:1, 1.6:1.4, 1.7:1.3, 1.8:1.2, 1.9:1.1, 2:1, etc.

[0033] Preferably, in step (b), the flow rate of the water vapor is 5000-15000 sccm, for example, it can be 5000 sccm, 6000 sccm, 6500 sccm, 7000 sccm, 7500 sccm, 8000 sccm, 8500 sccm, 9000 sccm, 9500 sccm, 10000 sccm, 11000 sccm, 12000 sccm, 13000 sccm, 14000 sccm, 15000 sccm, etc.

[0034] Preferably, in step (b), the flow rate of trimethylaluminum is 5000-15000 sccm, for example, it can be 5000 sccm, 6000 sccm, 6500 sccm, 7000 sccm, 7500 sccm, 8000 sccm, 8500 sccm, 9000 sccm, 9500 sccm, 10000 sccm, 11000 sccm, 12000 sccm, 13000 sccm, 14000 sccm, 15000 sccm, etc.

[0035] Preferably, in step (b), the deposition temperature is 150-200°C, for example, it can be 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, etc., and the deposition pressure is 400-800Torr, for example, it can be 400Torr, 450Torr, 500Torr, 550Torr, 600Torr, 650Torr, 700Torr, 750Torr, 800Torr, etc.

[0036] Preferably, in step (b), the alternating cycle number is 20 to 300 times, for example, it can be 20 times, 40 times, 60 times, 80 times, 100 times, 120 times, 140 times, 160 times, 180 times, 200 times, 220 times, 240 times, 260 times, 280 times, 300 times, etc.

[0037] Preferably, in step (b), the nitrogen purge gas flow rate is 5000-15000sccm, for example, it can be 5000sccm, 6000sccm, 6500sccm, 7000sccm, 7500sccm, 8000sccm, 8500sccm, 9000sccm, 9500sccm, 10000sccm, 11000sccm, 12000sccm, 13000sccm, 14000sccm, 15000sccm, etc.

[0038] Preferably, the temperature of the annealing thermal repair treatment is 200-300°C, for example, it can be 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, etc., and the time of the annealing thermal repair treatment is 60-120s, for example, it can be 60s, 70s, 80s, 90s, 100s, 110s, 120s, etc.

[0039] Preferably, the annealing and thermal repairing treatment is performed in a nitrogen atmosphere.

[0040] Preferably, the flow rate of the nitrogen gas is 10 to 15 L / min, for example, 10 L / min, 11 L / min, 12 L / min, 13 L / min, 14 L / min, 15 L / min, etc.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The present invention uses laser non-destructive cutting to cut the entire cell sheet, using low-power infrared laser to reduce thermal effects, ensuring smooth cuts without thermal damage, ensuring the uniformity of ALD coating, better passivating dangling bonds, and reducing the occurrence of leakage current. The coolant used is deionized water, which can avoid charged particles from combining with dangling bonds at the cutting edge and affecting the subsequent AlO x Passivation effect of the passivation layer.

[0043] (2) The present invention performs a stacking and pressurizing treatment on the cut cell strips before the ALD coating treatment. Since the ALD deposition method has serious winding plating, the stacking and pressurizing treatment before coating can avoid the formation of a negatively charged AlOx passivation layer on the N side of the Topcon solar cell. On the one hand, it can allow electrons to be smoothly extracted from the negative electrode, and on the other hand, it can ensure the welding tension between the component end welding ribbon and the Pad point.

[0044] (3) The present invention utilizes ALD to perform a dual-process coating treatment on the cutting edge. First, a film is formed by ozone and TMA. This film has the characteristics of strong adhesion and scratch resistance, which can ensure the mechanical properties of the film. Then, a film is formed by water and TMA. This film has a fast formation rate, which can ensure process efficiency while passivating the exposed dangling bonds, increasing the parallel resistance of the battery, and thus reducing the edge leakage current.

[0045] (4) The present invention performs annealing on the cell after coating. High temperature annealing can increase the overall lattice thermal motion of the silicon crystal, repair the interface defects between the coating and the silicon crystal, and reduce edge leakage current.

[0046] (5) After the present invention performs ALD and annealing processes on the Topcon solar cells after cutting, the edge leakage current is reduced to 0.015~0.03A. DETAILED DESCRIPTION

[0047] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear; however, in the event of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, the use of "or" means "and / or" unless otherwise stated. In addition, the use of the term "including" and other forms is non-limiting.

[0048] It should be noted that the following description sets forth specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in a variety of other ways than those described herein, and those skilled in the art may make similar generalizations without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0049] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples were prepared according to existing methods or directly purchased from the market.

[0051] Example 1

[0052] This embodiment provides a method for reducing leakage current of a TOPCon solar cell after cutting, the method specifically comprising the following steps:

[0053] S1. Infrared laser cutting:

[0054] The whole cell is cut by laser non-destructive cutting to obtain smooth cutting edges;

[0055] The power of the infrared laser is 5W, the cutting temperature is 150° C., and the length of the grooves opened by the laser cutting at both ends of the battery cell is 0.5 mm.

[0056] S2. Lamination pressure treatment:

[0057] The cut cell strips are laminated and pressed to avoid the formation of negatively charged AlO on the N side of the Topcon solar cell. x Passivation layer;

[0058] The number of stacked battery strips is 2, and the pressurized pressure is 1N.

[0059] S3, deposition of AlO x Passivation layer:

[0060] The ALD passivation treatment for the cut edge is to plate AlO in the ALD equipment after cutting the battery strip. x Passivation layer, AlO x The thickness of the passivation layer is 10 nm;

[0061] (a) After the laminated and pressurized battery strips are placed in an atomic deposition device, the chamber is evacuated, and ozone and trimethylaluminum are alternately introduced for deposition, followed by nitrogen purge.

[0062] The ratio of ozone to trimethylaluminum was 1:25; the ozone flow rate was 200 sccm; the trimethylaluminum flow rate was 5000 sccm; the alternating cycles were 50 times; the deposition temperature was 160° C., the deposition pressure was 500 Torr; and the nitrogen purge gas flow rate was 5000 sccm.

[0063] (b) evacuating the chamber, alternately introducing water vapor and trimethylaluminum for deposition, and then purging with nitrogen;

[0064] The introduction ratio of water vapor and trimethylaluminum is 1:1; the flow rate of water vapor is 10,000 sccm; the flow rate of trimethylaluminum is 10,000 sccm; the number of alternating cycles is 50 times; the deposition temperature is 160°C, the deposition pressure is 500 Torr; and the nitrogen purge gas flow rate is 5,000 sccm.

[0065] S4, annealing thermal repair treatment

[0066] Performing annealing and thermal repair on the coated battery strip to obtain a repaired battery strip;

[0067] The temperature of the annealing and thermal repair treatment is 200° C., the time of the annealing and thermal repair treatment is 120 s, and the flow rate of nitrogen is 10 L / min.

[0068] Example 2

[0069] This embodiment provides a method for reducing leakage current of a TOPCon solar cell after cutting, the method specifically comprising the following steps:

[0070] S1. Infrared laser cutting:

[0071] The whole cell is cut by laser non-destructive cutting to obtain smooth cutting edges;

[0072] The power of the infrared laser is 25W, the cutting temperature is 200°C, and the length of the slots opened by the laser cutting at both ends of the battery cell is 2mm.

[0073] S2. Lamination pressure treatment:

[0074] The cut cell strips are laminated and pressed to avoid the formation of negatively charged AlO on the N side of the Topcon solar cell. x Passivation layer;

[0075] Among them, the number of stacked battery strips is 5, and the pressing pressure is 2N.

[0076] S3, deposition of AlO x Passivation layer:

[0077] The ALD passivation treatment for the cut edge is to plate AlO in the ALD equipment after cutting the battery strip. x Passivation layer, AlO x The thickness of the passivation layer is 20 nm;

[0078] (a) After the laminated and pressurized battery strips are placed in an atomic deposition device, the chamber is evacuated, and ozone and trimethylaluminum are alternately introduced for deposition, followed by nitrogen purge.

[0079] The ratio of ozone to trimethylaluminum was 1:15; the ozone flow rate was 400 sccm; the trimethylaluminum flow rate was 6000 sccm; the alternating cycles were 100 times; the deposition temperature was 180° C., the deposition pressure was 600 Torr; and the nitrogen purge gas flow rate was 10000 sccm.

[0080] (b) evacuating the chamber, alternately introducing water vapor and trimethylaluminum for deposition, and then purging with nitrogen;

[0081] The ratio of water vapor to trimethylaluminum is 1:2; the flow rate of water vapor is 5000 sccm; the flow rate of trimethylaluminum is 10000 sccm; the number of alternating cycles is 100 times; the deposition temperature is 180°C, the deposition pressure is 600 Torr; and the nitrogen purge gas flow rate is 10000 sccm.

[0082] S4, annealing thermal repair treatment

[0083] Performing annealing and thermal repair on the coated battery strip to obtain a repaired battery strip;

[0084] The temperature of the annealing and thermal repair treatment is 250° C., the time of the annealing and thermal repair treatment is 90 seconds, and the flow rate of nitrogen is 12 L / min.

[0085] Example 3

[0086] This embodiment provides a method for reducing leakage current of a TOPCon solar cell after cutting, the method specifically comprising the following steps:

[0087] S1. Infrared laser cutting:

[0088] The whole cell is cut by laser non-destructive cutting to obtain smooth cutting edges;

[0089] The power of the infrared laser is 50W, the cutting temperature is 250°C, and the length of the grooves cut by laser cutting at both ends of the battery cell is 3mm.

[0090] S2. Lamination pressure treatment:

[0091] The cut cell strips are laminated and pressed to avoid the formation of negatively charged AlO on the N side of the Topcon solar cell. x Passivation layer;

[0092] Among them, the number of stacked battery strips is 10, and the pressing pressure is 3N.

[0093] S3, deposition of AlO x Passivation layer:

[0094] The ALD passivation treatment for the cut edge is to plate AlO in the ALD equipment after cutting the battery strip. x Passivation layer, AlO x The thickness of the passivation layer is 40 nm;

[0095] (a) After the laminated and pressurized battery strips are placed in an atomic deposition device, the chamber is evacuated, and ozone and trimethylaluminum are alternately introduced for deposition, followed by nitrogen purge.

[0096] The ratio of ozone to trimethylaluminum was 1:35; the ozone flow rate was 300 sccm; the trimethylaluminum flow rate was 10,500 sccm; the alternating cycles were 200 times; the deposition temperature was 200° C., the deposition pressure was 700 Torr; and the nitrogen purge gas flow rate was 15,000 sccm.

[0097] (b) evacuating the chamber, alternately introducing water vapor and trimethylaluminum for deposition, and then purging with nitrogen;

[0098] The introduction ratio of water vapor and trimethylaluminum is 2:1; the flow rate of water vapor is 10,000 sccm; the flow rate of trimethylaluminum is 5,000 sccm; the number of alternating cycles is 100 times; the deposition temperature is 200°C, the deposition pressure is 700 Torr; and the nitrogen purge gas flow rate is 15,000 sccm.

[0099] S4, annealing thermal repair treatment

[0100] Performing annealing and thermal repair on the coated battery strip to obtain a repaired battery strip;

[0101] The temperature of the annealing and thermal repair treatment is 300° C., the time of the annealing and thermal repair treatment is 60 seconds, and the flow rate of nitrogen is 15 L / min.

[0102] Example 4

[0103] This embodiment provides a method for reducing leakage current of TOPCon solar cells after cutting. The only difference from Example 1 is that in S1, the power of the infrared laser is 4W and the laser cutting temperature is 120°C; the other steps are exactly the same as Example 1.

[0104] Example 5

[0105] This embodiment provides a method for reducing leakage current of TOPCon solar cells after cutting. The only difference from Example 1 is that in S1, the power of the infrared laser is 60W and the laser cutting temperature is 300°C; the other steps are exactly the same as Example 1.

[0106] Example 6

[0107] This embodiment provides a method for reducing leakage current of a TOPCon solar cell after cutting. The only difference from the embodiment 1 is that in S2, the pressing pressure is 0.5N; the other steps are completely consistent with the embodiment 1.

[0108] Example 7

[0109] This embodiment provides a method for reducing leakage current of a TOPCon solar cell after cutting. The only difference from Example 1 is that in step (a) of S3, the introduction ratio of ozone and trimethylaluminum is 1:10; the flow rate of ozone is 1000 sccm; the flow rate of trimethylaluminum is 10000 sccm; and the other steps are exactly the same as in Example 1.

[0110] Example 8

[0111] This embodiment provides a method for reducing leakage current of a TOPCon solar cell after cutting. The only difference from Example 1 is that in step (a) of S3, the ratio of ozone to trimethylaluminum is 1:40; the flow rate of ozone is 150 sccm; and the flow rate of trimethylaluminum is 6000 sccm. The other steps are exactly the same as in Example 1.

[0112] Example 9

[0113] This embodiment provides a method for reducing leakage current of a TOPCon solar cell after cutting. The only difference from Example 1 is that in step (b) of S3, the introduction ratio of water vapor and trimethylaluminum is 1:3; the flow rate of the water vapor is 5000 sccm; the flow rate of the trimethylaluminum is 15000 sccm; and the other steps are exactly the same as in Example 1.

[0114] Example 10

[0115] This embodiment provides a method for reducing leakage current of a TOPCon solar cell after cutting. The only difference from Example 1 is that in step (b) of S3, the ratio of water vapor and trimethylaluminum introduced is 3:1; the flow rate of the water vapor is 15000 sccm; the flow rate of the trimethylaluminum is 5000 sccm; and the other steps are exactly the same as in Example 1.

[0116] Comparative Example 1

[0117] This comparative example provides a method for reducing leakage current of TOPCon solar cells after cutting. The only difference from Example 1 is that in S1, a fiber laser is used for cutting with a laser power of 600 W; the other steps are exactly the same as Example 1.

[0118] Comparative Example 2

[0119] This comparative example provides a method for reducing leakage current of TOPCon solar cells after cutting. The only difference from Example 1 is that in S2, no pressure treatment is performed during the stacking process; the other steps are exactly the same as Example 1.

[0120] Comparative Example 3

[0121] This comparative example provides a method for reducing leakage current of a TOPCon solar cell after cutting. The only difference from Example 1 is that in S3, the steps of alternately introducing water vapor and depositing trimethylaluminum are no longer performed. The other steps are exactly the same as those in Example 1.

[0122] Comparative Example 4

[0123] This comparative example provides a method for reducing leakage current of a TOPCon solar cell after cutting. The only difference from Example 1 is that the S4 annealing thermal repair treatment is no longer performed; the other steps are exactly the same as those in Example 1.

[0124] Test Case

[0125] Test samples: battery bars repaired by the methods of Examples 1 to 10, and battery bars repaired by the methods of Comparative Examples 1 to 4.

[0126] Test method:

[0127] Electrical performance test: Use solar energy simulation electrical efficiency tester to test under standard conditions (air quality AM1.5, light intensity 1000W / m 2 , test temperature 25℃).

[0128] The specific test results are shown in Table 1 below:

[0129] Table 1

[0130]

[0131] As shown in Table 1, the battery strips repaired by the method of the present invention have the advantages of high photoelectric conversion efficiency, low series resistance, and large short-circuit current. This fully illustrates that in the present invention, first, the whole battery sheet is cut by laser non-destructive cutting to obtain battery strips with smooth cutting edges, reducing thermal effects and ensuring smooth cutting seams without thermal damage, thereby further ensuring the subsequent atomic deposition (ALD) AlO plating. x Secondly, the present invention applies pressure to the stacking process of the cut battery strips. This is because the ALD deposition method has serious winding plating. The stacking and pressurizing process before coating can avoid the formation of negatively charged AlO on the N side of the Topcon solar cell. x The passivation layer, on the one hand, allows electrons to be smoothly extracted from the negative electrode, and on the other hand, ensures the welding tension between the component end welding ribbon and the pad point. Third, the present invention adopts the atomic deposition (ALD) method to passivate the edges of the laminated battery strips, ensuring process efficiency while passivating the exposed dangling bonds, thereby reducing edge leakage current. Fourth, the present invention anneals the coated battery cells. High-temperature annealing can increase the overall lattice thermal motion of the silicon crystal, repair the interface defects between the coating and the silicon crystal, and reduce edge leakage current.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for reducing leakage current of TOPCon solar cells after cutting, characterized in that: The method comprises the following steps: The solar cell is cut by laser cutting; wherein the laser cutting adopts an infrared laser, the power of the infrared laser is 5 to 50W, and the temperature of the laser cutting is 150 to 250°C; The cut battery strips are subjected to a lamination and pressurization process; wherein the pressurization pressure during the lamination and pressurization process is ≥1N; Atomic deposition is used to deposit AlO on the edge of the stacked and pressed battery strips. x Passivation layer; Wherein, the AlO x The passivation layer is prepared by the following steps: (a) placing the laminated and pressurized battery strips in an atomic deposition apparatus, evacuating the chamber, alternately introducing ozone and trimethylaluminum for deposition, and then purging with nitrogen; wherein the ratio of ozone to trimethylaluminum is 1:(15-35), the flow rate of ozone is 200-600 sccm, the flow rate of trimethylaluminum is 5000-15000 sccm; and the flow rate of trimethylaluminum is 5000-15000 sccm; (b) evacuating the chamber, alternately introducing water vapor and trimethylaluminum for deposition, and then purging with nitrogen; wherein the introduction ratio of the water vapor and trimethylaluminum is (1-2):(2-1); the flow rate of the water vapor is 5000-15000 sccm; the flow rate of the trimethylaluminum is 5000-15000 sccm; The passivated battery bar is subjected to annealing and thermal repair treatment to obtain a repaired battery bar.

2. The method for reducing leakage current of a TOPCon solar cell after cutting according to claim 1, characterized in that: The laser cutting creates grooves at both ends of the battery cell with a length of 0 to 3 mm.

3. The method for reducing leakage current of a TOPCon solar cell after cutting according to claim 1, characterized in that: During the lamination and pressurization process, the number of battery strips in the lamination is ≥2.

4. The method for reducing leakage current of a TOPCon solar cell after cutting according to claim 1, characterized in that: The AlO x The thickness of the passivation layer is 4 to 60 nm.

5. The method for reducing leakage current of TOPCon solar cells after cutting according to claim 1, characterized in that: In step (a), the deposition temperature is 150-200° C., and the deposition pressure is 400-800 Torr.

6. The method for reducing leakage current of a TOPCon solar cell after cutting according to claim 1, characterized in that: In step (a), the alternating cycles are performed 20 to 300 times.

7. The method for reducing leakage current of a TOPCon solar cell after cutting according to claim 1, characterized in that: In step (a), the nitrogen purge gas flow rate is 5000 to 15000 sccm.

8. The method for reducing leakage current of a TOPCon solar cell after cutting according to claim 1, characterized in that: In step (b), the deposition temperature is 150-200° C., and the deposition pressure is 400-800 Torr.

9. The method for reducing leakage current of a TOPCon solar cell after cutting according to claim 1, characterized in that: In step (b), the alternating cycles are performed 20 to 300 times.

10. The method for reducing leakage current of a TOPCon solar cell after cutting according to claim 1, characterized in that: In step (b), the nitrogen purge gas flow rate is 5000 to 15000 sccm.

11. The method for reducing leakage current of a TOPCon solar cell after cutting according to claim 1, characterized in that: The temperature of the annealing heat repair treatment is 200-300° C., and the time of the annealing heat repair treatment is 60-120 seconds.

12. The method for reducing leakage current of a TOPCon solar cell after cutting according to claim 1 or 11, characterized in that: The annealing and thermal repairing process is performed in a nitrogen atmosphere.

13. The method for reducing leakage current of a TOPCon solar cell after cutting according to claim 12, characterized in that: The flow rate of the nitrogen is 10-15 L / min.

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