Method for repairing edge cutting loss of solar cell and evaluation method

Abstract

The present invention relates to the field of solar cells. Disclosed are a method for repairing edge cutting loss of a solar cell and an evaluation method. Firstly, in the repair method of the present invention, ozone water is used to cool a cut surface of a silicon wafer after laser treatment; during cooling, oxygen is released upon heating, thereby forming an oxide layer on the cut surface of the silicon wafer and achieving prompt protection of the cut surface of the silicon wafer. In the present invention, a mixed solution of sulfonic acid compounds using hydrogen peroxide as a solvent is used as an organic / inorganic composite passivation solution, and the formed passivation film exhibits stronger high-temperature resistance and better passivation durability compared with conventional passivation films. In addition, the evaluation method of the present invention eliminates various environmental and testing error factors, other than experimental conditions, for the same silicon wafer during testing, reduces testing time and the number of sample wafers used, and enables accurate test results to be obtained in a short time.

Description

A method for repairing and evaluating edge cutting losses in solar cells. Technical Field

[0001] This invention relates to the field of solar cells, and in particular to a method for repairing and evaluating edge cutting losses in solar cells. Background Technology

[0002] To further reduce internal losses in solar cell modules and increase output power, laser-cut half-cell, multi-cell, and shingled module technologies have been developed. These technologies involve cutting a full-cell solar cell into 1 / 2, 1 / 3, or 1 / n cells, which are then connected in series and parallel for assembly. This reduces internal current and line resistance, thereby lowering power loss and increasing module output power and electricity generation. Therefore, half-cell and shingled module technologies have become the mainstream module technologies in the industry.

[0003] The current method for cutting solar cells is mainly non-destructive cutting. The principle is as follows: a laser is used to locally and rapidly heat the silicon substrate material. The subsequent cooling technology (usually spraying cooling water onto the laser-treated area) generates a non-uniform temperature field. This temperature field will generate a temperature gradient on the material surface, thereby inducing thermal stress. The laser spot is in a compressive stress state, while the area before and after the laser spot is in a tensile stress state. Since the compressive stiffness of brittle materials is much greater than their tensile strength, when the tensile stress reaches the material's fracture strength, the material will fracture. The fracture will stably expand along the moving trajectory of the laser and subsequent cooling.

[0004] Compared to traditional destructive cutting methods, the aforementioned non-destructive cutting method reduces the problem of excessive damage to battery performance during laser ablation. However, it is unavoidable that the silicon surface at the edge of the cut will still be directly exposed to the air, introducing a large number of dangling bonds and defect states, which become effective recombination centers for charge carriers, thus reducing battery performance. Taking current high-efficiency N-type TOPCon solar cells as an example, the absolute value of battery efficiency decreases by 0-0.3% after cutting.

[0005] To repair edge-cut damage in solar cells, current technologies commonly employ ALD (Alternating Current Deposition) to deposit an alumina dielectric film at the silicon wafer cut edges for passivation. However, this method requires substantial investment in ALD equipment, resulting in relatively low cost-effectiveness. In contrast, passivation using an organic solution-based passivation solution offers advantages such as low cost and operational flexibility, attracting widespread market attention. However, conventional passivation solutions are often composed of pure organic solutions, which undergo multiple high-temperature processes during module manufacturing (such as infrared stringing and lamination). This leads to a significant degradation in the initial passivation performance of the organic passivation solution, making it impossible to maintain the initially high passivation performance in the final module product. Therefore, finding new methods to further passivate edge-cut damage is crucial for reducing edge recombination and improving the module's CTM (Cost Per Module) value. Summary of the Invention

[0006] First, this invention provides a method for repairing edge-cutting damage in solar cells. This invention uses ozone water to cool the laser-treated silicon wafer cut surface, which releases oxygen upon heating during cooling, thereby forming an oxide layer on the cut surface and providing timely protection. This invention uses a sulfonic acid compound mixed solution with hydrogen peroxide as a solvent as an organic / inorganic composite passivation solution. The resulting passivation film exhibits stronger high-temperature resistance and better passivation durability compared to conventional organic passivation films.

[0007] Secondly, this invention provides an evaluation method for the repair effect of edge cutting loss of solar cells. This evaluation method can eliminate various environmental and test error factors other than experimental conditions on the same silicon wafer during the test process. At the same time, it can also reduce the test time and the amount of sample wafers used, and obtain more accurate test results in a shorter time.

[0008] The specific technical solution of this invention is as follows:

[0009] In a first aspect, the present invention provides a method for repairing edge cutting losses in solar cells, which specifically includes the following steps:

[0010] S1. Using ozone water as cooling water, ozone water is sprayed onto the laser-cut area on the silicon wafer immediately after laser treatment to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in a timely manner.

[0011] This invention discovers that in the gap between laser-cutting a silicon wafer and coating the cut surface with a passivation film, on the one hand, the cut surface is still briefly exposed to air, introducing a large number of dangling bonds and defect states, which become effective recombination centers for charge carriers, reducing battery performance; on the other hand, the complex composition of the local air during laser cutting also contaminates the cut surface. Therefore, this invention cleverly uses ozone water instead of conventional pure water to cool the laser-treated silicon wafer cut surface in a timely manner. Because laser treatment generates instantaneous high temperatures at the cut point, when ozone water is sprayed onto this area for cooling, it releases a suitable amount of oxygen upon heating, thus forming a thin oxide layer on the cut surface to protect it.

[0012] S2. A mixed solution of sulfonic acid compounds with hydrogen peroxide as solvent is used as an organic / inorganic composite passivation solution, which is coated on the cut surface of the silicon wafer and cured by heating in an oxygen-rich environment to form a passivation film.

[0013] In existing technologies, to repair edge cutting damage in solar cells, it has been reported to use organic solutions as passivation solutions to coat the cut surfaces of silicon wafers to form a passivation film. The drawback of this method is that the module manufacturing process involves multiple high-temperature processes (such as infrared stringing and lamination), which can significantly degrade the passivation performance of the passivation film formed by the organic solution, making it impossible to maintain the initially high passivation performance in the final module product. Therefore, this invention uses hydrogen peroxide as a solvent, with the addition of sulfonic acid compounds. The resulting passivation solution is an organic / inorganic composite passivation solution. After being coated onto the cut surface of the silicon wafer, heating accelerates the cross-linking reaction between organic molecules in the organic / inorganic composite passivation solution and promotes their bonding with the substrate surface. Specifically, during the heating process, the active functional groups in the organic molecules react with atoms or functional groups on the substrate surface to form covalent bonds.

[0014] Preferably, in S1, the concentration of ozone in the ozone water is 1 to 10 mg / L.

[0015] If the concentration of ozone water is too low, the amount of oxygen volatilized during the cell cutting process will be insufficient to form a dense oxide layer on the cut side of the silicon wafer, and airborne impurities will still contaminate the cut edges. If the concentration of ozone water is too high, it will lead to excessive oxygen volatilization during the cutting process. While this may result in a denser oxide film forming on the cut side, it will also significantly affect the grid lines on the cell surface, causing severe oxidation of the grid lines. This increases the line resistance of the grid lines, raising the series resistance of the entire cell and affecting the final electrical performance.

[0016] Preferably, in S2, the concentration of hydrogen peroxide in the organic / inorganic composite passivation solution is 5-20 wt%, and the concentration of sulfonic acid compound is 10-50 wt%.

[0017] If the concentration of sulfonic acid compounds is too low, the passivation film formed after heating and curing the corresponding passivation solution on the cut side of the solar cell will not be dense, resulting in reduced passivation performance. If the concentration is too high, it will increase the flooding area on the silicon wafer surface after coating, affecting not only the appearance of the solar cell but also causing light-shielding loss. On the other hand, excessively high concentrations will require a longer time for the passivation solution to cure during heating, and are prone to incomplete curing and defects such as internal bubbles. If the concentration of hydrogen peroxide solvent is too low, the oxidation effect of the overall composite passivation solution will be limited, failing to form a dense oxide film on the cut side of the solar cell. If the concentration is too high, the sulfonic acid compounds will be difficult to fully dissolve in the hydrogen peroxide solution, resulting in an uneven passivation solution after mixing.

[0018] Preferably, the oxygen content of the oxygen-rich environment in S2 is 30-50 vol%.

[0019] Preferably, in S2, the heating temperature is 100-150°C and the heating time is 1-10 min.

[0020] Secondly, the present invention provides a method for evaluating the repair effect of edge cutting loss of solar cells, which specifically includes the following steps:

[0021] 1) Using ozone water as cooling water, ozone water is sprayed immediately after laser treatment on the laser-cut area of ​​the silicon wafer to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in time.

[0022] 2) Select the cut silicon wafers as samples and perform the first electrical performance and / or PL test on them.

[0023] 3) Divide the cut side of the silicon wafer into at least one blank control area (non-passivated) and at least one passivated test area.

[0024] 4) Apply different passivation solutions to the surface of the corresponding passivation test area to form a passivation film.

[0025] 5) Conduct a second electrical performance and / or PL test on the solar cells in different regions and compare the results with the first test results.

[0026] In the prior art, the general steps for evaluating conventional edge passivated solar cells are: (1) performing corresponding electrical performance or PL tests after conventional silicon wafer cutting; (2) applying passivation solution; and (3) performing electrical performance or PL tests again. Since the silicon wafer is inevitably exposed to air for a period of time between cutting and passivation solution application, the cut side is inevitably affected by the natural oxide layer, which can lead to errors between the test results and the actual situation, thus increasing the risk of misjudgment. Therefore, this invention provides the above-mentioned evaluation method. According to this method, various environmental and test error factors other than experimental conditions can be eliminated during the testing process for the same silicon wafer. At the same time, the testing time and sample quantity can be reduced, and more accurate test results can be obtained in a shorter time.

[0027] Preferably, in step 1), the concentration of ozone in the ozone water is 1 to 10 mg / L.

[0028] Preferably, in 3), each region has the same size.

[0029] Preferably, in 4), one of the passivation solutions is an organic / inorganic composite passivation solution, which is a mixed solution of sulfonic acid compounds with hydrogen peroxide as a solvent; wherein the concentration of hydrogen peroxide is 5-20 wt% and the concentration of sulfonic acid compounds is 10-50 wt%.

[0030] As a preferred embodiment, in step 4), a passivation film is formed by heating and curing in an oxygen-rich environment.

[0031] More preferably, the oxygen content of the oxygen-rich environment is 30-50 vol%.

[0032] More preferably, the heating and curing temperature is 100-150°C and the time is 1-10 min.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] (1) This invention cleverly uses ozone water instead of conventional pure water to cool the cut surface of a silicon wafer after laser treatment. Ozone water can release a suitable amount of oxygen when heated while cooling, thereby forming a thin oxide layer on the cut surface of the silicon wafer in a timely manner, thus achieving timely protection of the cut surface of the silicon wafer.

[0035] (2) In this invention, an aqueous solution of hydrogen peroxide containing poly-4-styrene sulfonic acid is used as an organic / inorganic composite passivation solution. After being coated onto the cut surface of a silicon wafer, it can be heated in an oxygen-rich environment to form a passivation film. Compared with conventional passivation films, this passivation film has stronger high-temperature resistance and better passivation durability.

[0036] (3) The present invention provides an evaluation method for the repair effect of edge cutting loss of solar cells. According to the evaluation method of the present invention, various environmental and test error factors other than experimental conditions can be eliminated during the test process. At the same time, the test time and sample wafer usage can be reduced, and more accurate test results can be obtained in a shorter time. Attached Figure Description

[0037] Figure 1 shows the PL test results of the finished whole solar cell before cutting (a) and the PL test results of the solar cell after cutting in half (b).

[0038] Figure 2 shows the appearance of the side of the battery cell after cutting (a) without coating and after coating with organic / inorganic composite passivation liquid (b) in Embodiment 1 of the present invention.

[0039] Figure 3 shows the PL test results after the battery cell is cut (a), the PL test results after coating with organic / inorganic composite passivation liquid (b), and the PL test results after simulating infrared stringing high temperature (c) in Example 1 of the present invention.

[0040] Figure 4 is a photograph of the appearance of the small assembly after the battery cells are laminated according to Embodiment 1 of the present invention.

[0041] Figure 5 shows the PL test results after the battery cell is cut (a), the PL test results after coating with organic / inorganic composite passivation liquid (b), and the PL test results of the laminated small component (c) in Embodiment 1 of the present invention.

[0042] Figure 6 shows the PL test results after the battery cell was cut in Comparative Example 1 (a), the PL test results after coating with conventional organic passivation solution (b), and the PL test results after simulating infrared stringing at high temperature (c).

[0043] Figure 7 shows the PL test results after the battery cell was cut in Comparative Example 1 (a), the PL test results after coating with conventional organic passivation liquid (b), and the PL test results of the laminated small assembly (c).

[0044] Figure 8 shows the PL test results after the battery cell was cut in Comparative Example 2 (a), the PL test results after coating with conventional organic passivation liquid (b), and the PL test results after simulating infrared stringing high temperature (c).

[0045] Figure 9 shows the PL test results after the battery cell was cut (a), the PL test results after coating with conventional organic passivation liquid (b), and the PL test results of the laminated small component (c) in Comparative Example 2.

[0046] Figure 10 is a flowchart illustrating the evaluation method of Embodiment 2 of the present invention.

[0047] Figure 11 shows the PL test results after coating the cut side of the battery cell with organic / inorganic passivation liquid in Example 2 of the present invention.

[0048] Figure 12 shows the battery PL test results in the blank control area and the two passivation test areas after coating with passivation liquid in Example 3 of the present invention.

[0049] Figure 13 shows the battery PL test results in the blank control area and the two passivation test areas after coating with passivation liquid in Example 4 of the present invention. Detailed Implementation

[0050] The present invention will be further described below with reference to embodiments.

[0051] General Implementation Examples

[0052] First, a method for repairing edge cutting damage in solar cells specifically includes the following steps:

[0053] S1. Using ozone water as cooling water, ozone water is sprayed onto the laser-cut area on the silicon wafer immediately after laser treatment to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in a timely manner.

[0054] This invention discovers that in the gap between laser-cutting a silicon wafer and coating the cut surface with a passivation film, on the one hand, the cut surface is still briefly exposed to air, introducing a large number of dangling bonds and defect states, which become effective recombination centers for charge carriers, reducing battery performance; on the other hand, the complex composition of the local air during laser cutting also contaminates the cut surface. Therefore, this invention cleverly uses ozone water instead of conventional pure water to cool the laser-treated silicon wafer cut surface in a timely manner. Because laser treatment generates instantaneous high temperatures at the cut point, when ozone water is sprayed onto this area for cooling, it releases a suitable amount of oxygen upon heating, thus forming a thin oxide layer on the cut surface to protect it.

[0055] In some preferred embodiments, in S1, the concentration of ozone in the ozone water is 1–10 mg / L. If the concentration of ozone water is too low, the amount of oxygen volatilized during the cell cutting process is insufficient to form a dense oxide layer on the cut side of the silicon wafer, and airborne impurities will still contaminate the cutting edge. If the concentration of ozone water is too high, it will lead to excessive oxygen volatilization during the cutting process. While this may result in a denser oxide film forming on the cut side, it will also significantly affect the grid lines on the cell surface, causing severe oxidation of the grid lines. This increases the line resistance of the grid lines, raising the series resistance of the entire cell and affecting the final electrical performance.

[0056] S2. A mixed solution of sulfonic acid compounds with hydrogen peroxide as solvent is used as an organic / inorganic composite passivation solution, which is coated on the cut surface of a silicon wafer and heated in an oxygen-rich environment to form a passivation film.

[0057] In existing technologies, to repair edge cutting damage in solar cells, it has been reported to use organic solutions as passivation solutions to coat the cut surfaces of silicon wafers to form passivation films. The drawback of this method is that the module manufacturing process involves multiple high-temperature processes (such as infrared stringing and lamination), which can significantly degrade the passivation performance of the passivation film formed by the organic solution, making it impossible to maintain the initially high passivation performance in the final module product. Therefore, this invention uses hydrogen peroxide as a solvent, with the addition of sulfonic acid compounds. The resulting passivation solution is an organic / inorganic composite passivation solution. The passivation film formed after coating the cut surface of the silicon wafer exhibits stronger high-temperature resistance and better passivation durability compared to conventional passivation films.

[0058] In some preferred embodiments, in S2, the concentration of hydrogen peroxide in the organic / inorganic composite passivation solution is 5-20 wt%, and the concentration of sulfonic acid compound is 10-50 wt%. If the concentration of sulfonic acid compound is too low, the passivation film formed after heating and curing on the cut side of the battery cell after coating with the corresponding passivation solution will not be dense, resulting in reduced passivation performance. If the concentration is too high, it will increase the flooding area on the silicon wafer surface after coating, affecting not only the appearance of the front of the battery cell but also causing light-shielding loss. On the other hand, excessively high concentrations will require a longer time for the passivation solution to cure during heating, and are prone to incomplete curing and defects such as internal bubbles. If the concentration of the solvent hydrogen peroxide is too low, the oxidation effect of the overall composite passivation solution will be limited, and a dense oxide film cannot be formed on the cut side of the battery cell. If the concentration is too high, the sulfonic acid compound will be difficult to fully dissolve in the hydrogen peroxide solution, resulting in an uneven passivation solution after mixing.

[0059] In some preferred embodiments, the oxygen content of the oxygen-enriched environment in S2 is 30–50 vol%.

[0060] In some preferred embodiments, in S2, the heating temperature is 100-150°C and the time is 1-10 minutes.

[0061] Secondly, an evaluation method for the repair effect of edge cutting loss of solar cells specifically includes the following steps:

[0062] 1) Using ozone water as cooling water, ozone water is sprayed immediately after laser treatment on the laser-cut area of ​​the silicon wafer to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in time.

[0063] In some preferred embodiments, in 1), the concentration of ozone in the ozone water is 1 to 10 mg / L.

[0064] 2) Select the cut silicon wafers as samples and perform the first electrical performance and / or PL test on them.

[0065] 3) Divide the cut side of the silicon wafer into at least one blank control area (non-passivated) and at least one passivated test area.

[0066] In some preferred implementations, in 3), each region has the same size.

[0067] 4) Apply different passivation solutions to the surface of the corresponding passivation test area to form a passivation film.

[0068] 5) Conduct a second electrical performance and / or PL test on the solar cells in different regions and compare the results with the first test results.

[0069] In the prior art, the general steps for evaluating conventional edge passivated solar cells are: (1) performing corresponding electrical performance or PL tests after conventional silicon wafer cutting; (2) applying passivation solution; and (3) performing electrical performance or PL tests again. Since the silicon wafer is inevitably exposed to air for a period of time between cutting and passivation solution application, the cut side is inevitably affected by the natural oxide layer, which can lead to errors between the test results and the actual situation, thus increasing the risk of misjudgment. Therefore, this invention provides the above-mentioned evaluation method. According to this method, various environmental and test error factors other than experimental conditions can be eliminated during the testing process for the same silicon wafer. At the same time, the testing time and sample quantity can be reduced, and more accurate test results can be obtained in a shorter time.

[0070] In some preferred embodiments, in 4), one of the passivation solutions is an organic / inorganic composite passivation solution, which is a mixed solution of sulfonic acid compounds with hydrogen peroxide as a solvent; wherein the concentration of the hydrogen peroxide solution is 5-20 wt%; and the concentration of the sulfonic acid compound is 10-50 wt%.

[0071] In some preferred embodiments, in 4), a passivation film is formed by heating and curing in an oxygen-rich environment.

[0072] In some more preferred embodiments, in 4), the oxygen content of the oxygen-enriched environment is 30-50 vol%.

[0073] In some more preferred embodiments, in 4), the temperature for heating and curing is 100-150°C and the time is 1-10 min.

[0074] Specific embodiments and comparative examples

[0075] (a) Repair methods for edge cutting damage of solar cells.

[0076] Example 1

[0077] A method for repairing edge cutting damage in solar cells, specifically including the following steps:

[0078] S1. Using ozone water with an ozone concentration of approximately 4 mg / L as cooling water, ozone water is sprayed onto the laser-cut area on the silicon wafer immediately after laser treatment to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in a timely manner.

[0079] S2. Using a hydrogen peroxide solution containing poly-4-styrene sulfonic acid as the organic / inorganic composite passivation solution, the concentration of the hydrogen peroxide solution in the organic / inorganic composite passivation solution is approximately 10 wt%, and the concentration of poly-4-styrene sulfonic acid is approximately 15 wt%. The organic / inorganic composite passivation solution is coated onto the diced surface of a silicon wafer and heated at 140°C for 3 min in an oxygen-rich environment with an oxygen content of approximately 35 vol% to form a passivation film.

[0080] Figure 1 shows the PL test results of the finished whole solar cell before cutting using the conventional cutting method (Figure 1(a)) and the PL test results of the solar cell after being cut in half (Figure 1(b)). The results show that the edge of the solar cell wafer in Figure 1(b) is obviously red after cutting, indicating that if passivation protection measures are not taken, the performance of the edge of the solar cell wafer will change significantly after cutting.

[0081] Figure 2 shows the appearance of the battery cell after cutting in Example 1 of the present invention, before and after coating with organic / inorganic composite passivation liquid (Figure 2(a)). Figure 3 shows the PL test results of the battery cell after cutting in Example 1 of the present invention (Figure 3(a)), after coating with organic / inorganic composite passivation liquid (Figure 3(b)), and after simulating infrared stringing high temperature (Figure 3(c)). The results show that the passivation film formed by coating the battery cell with organic / inorganic composite passivation liquid in Example 1 of the present invention can effectively passivate the cutting edge, and its passivation performance did not decrease significantly after the subsequent simulated infrared stringing process (the color of the battery cell cutting position did not turn significantly red after infrared stringing).

[0082] Figure 4 is a photograph of the appearance of the small component obtained after laminating the battery cells processed according to Embodiment 1 of the present invention.

[0083] Figure 5 shows the PL test results of the battery cell after cutting in Example 1 of the present invention (Figure 5(a)), the PL test results after coating with organic / inorganic composite passivation liquid (Figure 5(b)), and the PL test results of the laminated small module (Figure 5(c)). The results show that the passivation film formed by coating the battery cell with organic / inorganic composite passivation liquid in Example 1 of the present invention on the cutting side can not only effectively passivate the cutting edge, but also the passivation performance does not show a significant decrease after the subsequent module end lamination process (the color of the cutting position of the battery cell does not turn obviously red after lamination).

[0084] Comparative Example 1 (The only difference from Example 1 is that a conventional organic passivation solution was used in S2)

[0085] A method for repairing edge cutting damage in solar cells, specifically including the following steps:

[0086] S1. Using ozone water with an ozone concentration of approximately 4 mg / L as cooling water, ozone water is sprayed onto the laser-cut area on the silicon wafer immediately after laser treatment to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in a timely manner.

[0087] S2. An ethanol solution containing (2-(9H-carbazole-9-yl)ethyl)phosphonic acid was used as a conventional organic passivation solution. The concentration of (2-(9H-carbazole-9-yl)ethyl)phosphonic acid in the conventional organic passivation solution was about 10 wt%. The conventional organic passivation solution was then coated onto the silicon wafer dicing surface and heated to 100°C in air for 3 min to form a passivation film.

[0088] Figure 6 shows the PL test results of the battery cells in Comparative Example 1 after cutting (Figure 6(a)), the PL test results after coating with conventional organic passivation solution (Figure 6(b)), and the PL test results after simulating infrared stringing at high temperature (Figure 6(c)). The results show that although the conventional organic passivation solution in Comparative Example 1 can effectively passivate the cut edges of the battery cells after coating with the cut side to form a passivation film, its passivation performance will decrease significantly after the subsequent simulated infrared stringing process (the cut position of the battery cell turns significantly red after infrared stringing).

[0089] Figure 7 shows the PL test results of the cells after cutting in Comparative Example 1 (Figure 7(a)), the PL test results after coating with conventional organic passivation solution (Figure 7(b)), and the PL test results of the laminated module (Figure 7(c)). The results show that although the passivation film formed by coating the cut side of the cell with conventional organic passivation solution in Comparative Example 1 can effectively passivate the cut edge, the passivation performance will decrease significantly after the subsequent module end lamination process (the color of the cut position of the cell will turn obviously red after lamination).

[0090] Comparative Example 2 (The only difference from Example 1 is that a conventional organic passivation solution was used in S2)

[0091] A method for repairing edge cutting damage in solar cells, specifically including the following steps:

[0092] S1. Using ozone water with an ozone concentration of approximately 4 mg / L as cooling water, ozone water is sprayed onto the laser-cut area on the silicon wafer immediately after laser treatment to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in a timely manner.

[0093] S2. An ethanol solution containing perfluorosulfonic acid resin is used as a conventional organic passivation solution. The concentration of perfluorosulfonic acid resin in the conventional organic passivation solution is about 12 wt%. The conventional organic passivation solution is then coated onto the silicon wafer cutting surface and heated at 110°C for 3 min in an air environment to form a passivation film.

[0094] Figure 8 shows the PL test results of the battery cells in Comparative Example 2 after cutting (Figure 8(a)), the PL test results after coating with conventional organic passivation solution (Figure 8(b)), and the PL test results after simulating infrared stringing at high temperature (Figure 8(c)). The results show that although the conventional organic passivation solution in Comparative Example 2 can effectively passivate the cut edges of the battery cells after coating with the cut side to form a passivation film, its passivation performance will significantly decrease after the subsequent simulated infrared stringing process (the cut position of the battery cell turns significantly red after infrared stringing).

[0095] Figure 9 shows the PL test results of the cells after cutting in Comparative Example 2 (Figure 9(a)), the PL test results after coating with conventional organic passivation solution (Figure 9(b)), and the PL test results of the laminated module (Figure 7(c)). The results show that although the passivation film formed by coating the cut side of the cell with conventional organic passivation solution in Comparative Example 2 can effectively passivate the cut edge, the passivation performance will decrease significantly after the subsequent module end lamination process (the color of the cut position of the cell becomes obviously red after lamination).

[0096] (II) Evaluation of the repair effect of different passivation solutions on edge cutting loss of solar cells.

[0097] Example 2

[0098] An evaluation method for the repair effect of edge cutting loss of solar cells, which specifically includes the following steps:

[0099] 1) Using ozone water with an ozone concentration of 4 mg / L as cooling water, ozone water is sprayed immediately after laser treatment on the laser-cut area of ​​the silicon wafer to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in time.

[0100] 2) Select the cut silicon wafers as samples and perform the first PL test on them.

[0101] 3) Divide the cut side of the silicon wafer into a blank control area (non-passivated) and a passivation test area.

[0102] 4) The blank control area is not coated with passivation solution. The organic / inorganic composite passivation solution in Example 1 is coated on the surface of the passivation test area and heated at 140°C for 3 minutes in an oxygen-rich environment with an oxygen content of about 35 vol% to form a passivation film.

[0103] 5) Perform a second PL test on the blank control area and passivation test area of ​​the solar cell and compare the results with the first test.

[0104] Figure 10 is a schematic flowchart of the evaluation method in Embodiment 2 of the present invention. In this embodiment, since the blank control group and the passivation test group are both conducted on the same cut edge of the battery cell, any error influences outside the experimental conditions can be eliminated during the corresponding experiment, and the performance difference between the coated composite passivation solution and the uncoated passivation solution can be clearly compared.

[0105] Figure 11 shows the PL test results after coating the cut side of the battery cell with organic / inorganic passivation liquid in Example 2 of the present invention. As can be seen from Figure 11, the edge of the battery after coating with organic / inorganic passivation liquid becomes significantly brighter, while the uncoated area (blank control area) remains red. This test result directly proves that the passivation film formed by the organic / inorganic passivation liquid in Example 1 has a significant passivation effect.

[0106] Example 3 (The difference from Example 2 is that there are two passivation test areas. One passivation test area is coated with the conventional organic passivation solution in Comparative Example 1, and the other passivation test area is coated with the organic / inorganic composite passivation solution in Example 1.)

[0107] An evaluation method for the repair effect of edge cutting loss of solar cells, which specifically includes the following steps:

[0108] 1) Using ozone water with an ozone concentration of 4 mg / L as cooling water, ozone water is sprayed immediately after laser treatment on the laser-cut area of ​​the silicon wafer to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in time.

[0109] 2) Select the cut silicon wafers as samples and perform the first PL test on them.

[0110] 3) Divide the cut side of the silicon wafer into one blank control area (non-passivated) and two passivation test areas.

[0111] 4) The blank control area is not coated with passivation liquid. The organic / inorganic composite passivation liquid in Example 1 is coated on the surface of one passivation test area, and the conventional organic passivation liquid in Comparative Example 1 is coated on the surface of the other passivation test area. The reaction is carried out in an oxygen-rich environment with an oxygen content of about 35 vol% at 140°C for 3 min, and passivation films are formed in the two passivation test areas respectively.

[0112] 5) Perform a second PL test on the blank control area and two passivation test areas of the solar cell, and compare the results with the first test results.

[0113] Figure 12 shows the PL test results of the battery in Example 3 of this invention, including the blank control area and two passivation test areas after coating with passivation solution. In Example 3, the cut side of the battery cell is divided into three equal areas: the middle area is the blank control area, the upper area is the area after coating with the conventional organic passivation solution of Comparative Example 1, and the lower area is the area after coating with the organic / inorganic composite passivation solution of Example 1 of this invention. After PL testing, it can be clearly observed that the cut area coated with passivation solution is significantly brighter, while the blank control area remains reddish. Furthermore, the brightness of the area coated with the organic / inorganic composite passivation solution of Example 1 is slightly higher than that of the area covered by the conventional organic passivation solution of Comparative Example 1. This test result indicates that the organic / inorganic composite passivation solution of Example 1 has a better passivation effect than the conventional organic passivation solution of Comparative Example 1.

[0114] Example 4 (The difference from Example 2 is that there are two passivation test areas. One passivation test area is coated with the conventional organic passivation solution in Comparative Example 2, and the other passivation test area is coated with the organic / inorganic composite passivation solution in Example 1.)

[0115] An evaluation method for the repair effect of edge cutting loss of solar cells, which specifically includes the following steps:

[0116] 1) Using ozone water with an ozone concentration of 4 mg / L as cooling water, ozone water is sprayed immediately after laser treatment on the laser-cut area of ​​the silicon wafer to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in time.

[0117] 2) Select the cut silicon wafers as samples and perform the first PL test on them.

[0118] 3) Divide the cut side of the silicon wafer into one blank control area (non-passivated) and two passivation test areas.

[0119] 4) No passivation solution was applied to the blank control area. The organic / inorganic composite passivation solution from Example 1 was applied to the surface of one of the passivation test areas, and the conventional organic passivation solution from Comparative Example 2 was applied to the surface of the other passivation test area. The reaction was carried out at 140°C for 3 minutes in an oxygen-rich environment with an oxygen content of about 35 vol%. Passivation films were formed in the two passivation test areas.

[0120] 5) Perform a second PL test on the blank control area and two passivation test areas of the solar cell, and compare the results with the first test results.

[0121] Figure 13 shows the PL test results of the battery in Example 3 of this invention, specifically the blank control area and two passivation test areas after coating with passivation solution. In Example 3, the cut side of the battery cell was divided into three equal areas: the middle area was the blank control area, the upper area was the area after coating with the conventional organic passivation solution of Comparative Example 2, and the lower area was the area after coating with the organic / inorganic composite passivation solution of Example 1 of this invention. After PL testing, it was clearly observed that the cut area coated with passivation solution became significantly brighter, while the blank control area remained reddish. Furthermore, the brightness of the area coated with the organic / inorganic composite passivation solution of Example 1 was slightly higher than that of the area covered by the conventional organic passivation solution of Comparative Example 2. This test result indicates that the organic / inorganic composite passivation solution of Example 1 has a better passivation effect than the conventional organic passivation solution of Comparative Example 2. In summary, the testing method of this invention can not only accurately compare the differences between the control group and each experimental group, but also reduce the number of experimental cells and reduce costs.

[0122] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0123] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for repairing edge cutting damage of solar cells, characterized in that... include: S1. Using ozone water as cooling water, ozone water is sprayed immediately after laser treatment on the laser-cut area of ​​the silicon wafer to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in time. S2. A mixed solution of sulfonic acid compounds using hydrogen peroxide as a solvent is applied to the cut surface of a silicon wafer as an organic / inorganic composite passivation solution and cured by heating in an oxygen-rich environment to form a passivation film; the sulfonic acid compound is poly-4-styrene sulfonic acid.

2. The repair method according to claim 1, characterized in that: In S1, the concentration of ozone in the ozone water is 1 to 10 mg / L.

3. The repair method according to claim 1, characterized in that: In S2, the concentration of hydrogen peroxide in the organic / inorganic composite passivation solution is 5-20 wt%, and the concentration of sulfonic acid compound is 10-50 wt%.

4. The repair method according to claim 1, characterized in that: The oxygen content of the oxygen-rich environment in S2 is 30-50 vol%.

5. The repair method according to claim 1 or 4, characterized in that: In S2, the heating temperature is 100-150°C and the heating time is 1-10 minutes.

6. A method for evaluating the repair effect of edge cutting loss of solar cells, characterized in that... include: 1) Using ozone water as cooling water, ozone water is sprayed immediately after laser treatment on the laser-cut area of ​​the silicon wafer to cool it and create a local oxygen-rich environment, so that an oxide layer can be formed on the cut surface of the silicon wafer in time. 2) Perform the first electrical performance and / or PL test on the cut silicon wafer; 3) Divide the diced side of the silicon wafer into at least one blank control area and at least one passivation test area; 4) Different passivation solutions are coated onto the surface of the corresponding passivation test area to form a passivation film; one of the passivation solutions is an organic / inorganic composite passivation solution, which is a mixed solution of sulfonic acid compounds with hydrogen peroxide as solvent; the sulfonic acid compound is poly-4-styrene sulfonic acid; 5) Conduct a second electrical performance and / or PL test on the solar cells in different regions and compare the results with the first test results.

7. The evaluation method according to claim 6, characterized in that: In 1), the concentration of ozone in the ozone water is 1 to 10 mg / L.

8. The evaluation method according to claim 6, characterized in that: In 3), each region has the same size.

9. The evaluation method according to claim 6, characterized in that: In step 4), the concentration of hydrogen peroxide in the organic / inorganic composite passivation solution is 5–20 wt%, and the concentration of sulfonic acid compound is 10–50 wt%.

10. The evaluation method according to claim 9, characterized in that: 4) In the process, a passivation film is formed by heating and curing in an oxygen-rich environment.

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