Method and system for processing N-type TOPCon bad battery piece

Abstract

The invention discloses a processing method and system for an N-type TOPCon bad battery piece, and relates to the technical field of battery processing. By performing electric injection and laser sintering combined treatment on the battery piece or the cloud piece with the star-shaped subfissure, the defective battery piece is repaired, so that the production cost of the N-type TOPCon battery is reduced. By means of the system, industrialized screening and repairing of the N-type TOPCon bad battery pieces can be achieved, and the production efficiency of the N-type TOPCon is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery processing, and in particular to a method and system for processing an N-type TOPCon defective battery cell. Background Art

[0002] Solar cells are devices that directly convert light energy into electrical energy through the photoelectric effect or photochemical effect. They are mainly divided into crystalline silicon solar cells, thin-film solar cells and new solar cells. Currently, crystalline silicon solar cells are the most widely used. In the early stages of the industry, crystalline silicon solar cells mainly used Al-BSF cell technology (conventional aluminum back long cell technology). BSF cell technology is low-cost, has low cell conversion efficiency, and has inherent technical defects. With the maturity of PERC technology (rear local contact passivation) in 2017 and the decline in the cost of single crystals, PERC technology batteries have replaced BSF technology on a large scale.

[0003] In recent years, many companies in the photovoltaic field have focused on researching and developing high-efficiency crystalline silicon cells to improve the company's technical level and enhance the competitiveness of their products. The semiconductors of solar cells are divided into P-type and N-type due to their different doping elements. N-type crystalline silicon solar cells are more conducive to breakthroughs in battery conversion efficiency due to their excellent characteristics such as low light-induced attenuation, good stability, double-sided power generation, production line compatibility, and high limit efficiency. They have become the first choice for PERC cell upgrades. In terms of industrial upgrading, N-type TOPCon cells have become the best choice for RERC cell upgrades because they retain and utilize PERC cell equipment and technology to the greatest extent.

[0004] However, with the improvement of the efficiency of N-type solar cells, it is difficult to improve the yield of manufacturing cells. N-type solar cells have limitations in the technical process route. For example, the preparation of N-type TOPCon cells requires high temperature. When manufacturing cells, excessive pressure and unstable temperature will cause pressure inside the cell, which will cause star-shaped cracks. For the purpose of cost reduction, poor quality silicon materials are often used to make cell silicon wafers, which will also cause star-shaped cracks in the cell during processing. The introduction of laser sintering in the process has led to a gradual increase in the number of cloud sheets in the cell; after doping diffusion, the local square resistance of the cell silicon wafer is too large, and impurities introduced due to lax process hygiene control will also produce cloud sheets. These are all defective sheets. The current yield of TOPCon mass production is 93%-95%, which is lower than the yield of PERC. Therefore, while ensuring the high conversion rate of N-type TOPCon solar cells, seeking a method to improve their yield is a problem that needs to be solved in the field of solar cells. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for processing N-type TOPCon defective cells, which improves the yield rate of N-type TOPCon while ensuring the high conversion rate of N-type TOPCon by repairing the cells.

[0006] In order to achieve the above objectives, the present invention is implemented by the following technical solutions:

[0007] A method for processing an N-type TOPCon defective cell comprises the following steps:

[0008] (1) Electrical injection of N-type TOPCon defective cells;

[0009] (2) Laser sintering the N-type TOPCon defective cell after processing in step (1).

[0010] When the charging current is too large or the charging time is too long, plasma sputtering may occur inside the battery, resulting in electrode damage, further affecting the life and performance of the battery. Preferably, the current intensity of the electrical injection treatment in step (1) is 6A-10A. For example, it is 6A, 7A, 8A, 9A or 10A, but it is not limited to the listed numbers. Other listed values ​​within the numerical range are also applicable.

[0011] Preferably, the duration of the electrical injection treatment in step (1) is 500s-900s. For example, 500s, 550s, 600s, 650s,

[0012] 700s, 750s, 800s, 850s or 900s, but not limited to the listed numbers, other listed values ​​within the numerical range are also applicable.

[0013] When the power of laser sintering is too large, the damage to the silicon substrate is greater, so the composite current is larger, the contact resistance will also be larger, and the efficiency of the repaired battery cell will be affected. Preferably, the laser power in the laser sintering process in step (2) is 10%-30%. For example, it is 10%, 12%, 15%, 18%, 20%, 25%, 28% or 30%, but it is not limited to the listed numbers. Other listed values ​​within the numerical range are also applicable. The laser power in the present invention refers to the percentage of the laser output power to the maximum output power.

[0014] If the bias voltage of laser sintering is too high, it will cause reverse breakdown of solar cells, making both the illuminated area and the non-illuminated area conductive. Due to the current shunting effect, the local conductive current density in the illuminated area will be greatly reduced, and the Joule heat generated will also be reduced accordingly, resulting in an increase in the contact resistance between metal and silicon, and ultimately reducing the efficiency of the solar cell. Too high a bias voltage will lead to poor filling effect and affect the conversion efficiency of the battery cell. Preferably, in the step 2), the bias voltage in the laser sintering process is 36V-50V. For example, 36V, 37V, 38V, 39V, 40V, 42V, 45V, 47V, 49V or 50V, but not limited to the listed numbers, and other listed values ​​within the numerical range are also applicable.

[0015] Preferably, the electric injection is performed using an electric injection device, a plurality of TOPCon cells are stacked to form a cell stack or placed in sequence, and a forward bias voltage is applied to the cell stack to form carrier injection.

[0016] Preferably, the N-type TOPCon defective battery is an N-type TOPCon battery having star-shaped cracks and / or cloud sheet defects.

[0017] Preferably, after step (3), a performance test is performed on the TOP battery.

[0018] Preferably, the performance test includes an electrical performance test and an EL test.

[0019] The present invention also provides a system for processing N-type TOPCon defective battery cells, the system comprising an electric injection system, a laser sintering system, a support transmission system and a central control system, the support transmission system, the electric injection system and the support transmission system are arranged in sequence, an electric injection device is arranged in the electric injection system, a laser emitting device is arranged in the laser sintering system, and the central control system controls the operation of the transmission system, the electric injection system and the laser sintering system.

[0020] Preferably, the system can repair multiple defective battery cells at the same time.

[0021] Preferably, the transmission system can support one or more defective battery cells and transmit them between the electrical injection system and the laser sintering system.

[0022] Preferably, a plurality of electric injection points are provided in the electric injection system, so that electric injection processing can be performed on a plurality of defective batteries at one time.

[0023] Preferably, a plurality of laser emitters are provided in the laser sintering system, and the laser emitters can automatically adjust the power and bias voltage of the laser beam within a corresponding range according to the defect type of the defective battery.

[0024] Preferably, the control work of the central control system is that the central control system detects the N-type TOPCon battery cells to determine whether they are good cells or bad cells; if they are good cells, they are output as good cells and subsequent work is not started; if they are bad cells, the types of star-shaped cracks or cloud-shaped cells or both are determined, and the electric injection parameters and laser sintering parameter ranges are set according to the three different types; the central control system controls the transmission system to select the N-type TOPCon battery cells to be transported to different channels and to transmit them between the electric injection system and the transmission system.

[0025] Only laser sintering can repair the cloud defects of the cell to a certain extent, but the repair effect on the star-shaped hidden cracks of the cell is not obvious; for the defects caused by the crystal structure of the N-type TOPCon cell such as star-shaped hidden cracks, targeted repair can be carried out through the combined repair process of electric injection and laser sintering. During the electric injection process, the current will activate the carriers inside the battery, making it easier to flow, thereby improving the conductivity and photoelectric conversion efficiency of the battery. At the same time, electric injection can also promote the rearrangement of the lattice structure inside the battery, and this rearrangement helps to repair some tiny cracks and defects, including star-shaped hidden cracks. The principle of laser sintering to repair cloud sheets is mainly to irradiate the cell with high-intensity laser, excite charge carriers, and induce mutual diffusion of silver paste and silicon, thereby reducing the contact resistance between metal and semiconductor and improving the performance of the cell. It can be seen that the defective cell processing method of the present invention can not only carry out targeted repair of star-shaped hidden crack defective cells, but also can achieve the simultaneous repair of star-shaped hidden cracks and cloud defects at one time.

[0026] The present invention provides a method and system for processing N-type TOPCon defective cells, which has the following advantages compared with the prior art:

[0027] Beneficial effects:

[0028] The present invention aims at the problems of star-shaped hidden cracks and cloud sheets generated in the process of producing N-type TOPCon cells. The present invention adopts a combined treatment of electric injection and laser sintering, which can effectively repair the defects of star-shaped hidden cracks and cloud sheets of N-type TOPCon cells, greatly improving the product qualification rate, that is, ensuring the high conversion rate of solar cells, reducing production costs, and reducing waste loss.

[0029] At the same time, the system for processing N-type TOPCon defective cells adopted by the present invention realizes selective and targeted repair of cell defects, and improves the repair efficiency of defective cells. Moreover, the system is simple to operate and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 : This is the star-shaped hidden crack EL image of the N-type TOPCon defective cell before the repair process in Example 1;

[0031] Figure 2 : This is an EL image of an N-type TOPCon defective cell with a star-shaped hidden crack defect after being repaired by Example 1 of the present invention;

[0032] Figure 3 : EL image of the cloud sheet of the N-type TOPCon defective cell before the repair process in Example 2;

[0033] Figure 4 : EL image of an N-type TOPCon defective cell with clouded film after being repaired by Example 2 of the present invention;

[0034] Figure 5 : This is the EL image of an N-type TOPCon defective cell with both star-shaped hidden cracks and cloud-like pieces before repair in Example 3;

[0035] Figure 6 : This is an EL image of an N-type TOPCon defective cell with both star-shaped hidden cracks and cloud-like pieces after being repaired by the method of Example 3;

[0036] Figure 7 : This is an EL image of an N-type TOPCon defective cell with a star-shaped hidden crack defect after being repaired by the method of Example 4;

[0037] Figure 8 : This is an EL image of an N-type TOPCon defective cell with a star-shaped hidden crack defect after being repaired by the method of Example 5;

[0038] Fig. 9 : This is an EL image of an N-type TOPCon defective cell with a clouded film after being repaired by Example 4 of the present invention;

[0039] Fig.10 : EL image of an N-type TOPCon defective cell with clouded film after being repaired by Example 5 of the present invention;

[0040] Fig.11 : This is an EL image of an N-type TOPCon defective cell with a star-shaped hidden crack defect after being repaired by the method of Example 6;

[0041] Fig.12 : This is an EL image of an N-type TOPCon defective cell with a star-shaped hidden crack defect after being repaired by the method of Example 7;

[0042] Fig.13 : EL image of an N-type TOPCon defective cell with clouded film after being repaired by the method of Example 7;

[0043] Fig.14: This is an EL image of an N-type TOPCon defective cell with both star-shaped hidden cracks and cloud-like pieces after being repaired by the method of Example 7;

[0044] Fig.15 : This is an EL image of an N-type TOPCon defective cell with both star-shaped hidden cracks and cloud-like pieces after being repaired by the method of Example 4;

[0045] Fig.16 : This is an EL image of an N-type TOPCon defective cell with both star-shaped hidden cracks and cloud-like pieces after being repaired by the method of Example 5;

[0046] Fig.17 : EL image of an N-type TOPCon defective cell with both star-shaped hidden cracks and cloud-like pieces after being repaired by the method of comparative example 1;

[0047] Fig.18 : EL image of an N-type TOPCon defective cell with both star-shaped hidden cracks and cloud-like pieces after being repaired by the method of comparative example 2;

[0048] Fig.19 This is an EL image of an N-type TOPCon defective cell with clouded film after being repaired by the method of Comparative Example 3;

[0049] Fig. 20 : This is the EL image of an N-type TOPCon defective cell with a star-shaped hidden crack defect after being repaired by the method of comparative example 3. DETAILED DESCRIPTION

[0050] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0051] The embodiment of the present invention solves the problems of high defective rate of N-type TOPCon battery cells and high battery cost by providing a method and system for processing N-type TOPCon defective battery cells.

[0052] A method for processing an N-type TOPCon defective cell comprises the following steps:

[0053] (1) Performing electrical injection on the N-type TOPCon defective battery cell, the electrical injection treatment current intensity is 6A-10A, and the electrical injection treatment time is 500s-900s; (2) Performing laser sintering on the N-type TOPCon defective battery cell treated in step (1), the laser power in the laser sintering process is 10%-30%, and the bias voltage is 36V-50V.

[0054] A processing system for N-type TOPCon defective battery cells is provided, the system comprising an electric injection system, a laser sintering system, a support transmission system and a central control system. The electric injection system is provided with an electric injection device, the laser sintering system is provided with a laser emitting device, the support transmission system can support one or more defective battery cells and transmit between the electric injection system and the laser sintering system, the central control system controls the transmission of the support transmission system, identifies the defect type of the defective battery cell, and selects specific electric injection parameters and laser parameter ranges according to different defect types.

[0055] Specifically, the N-type TOPCon cell is placed in the processing system of the N-type TOPCon defective cell of the present invention, and the central control system detects the placed cell to determine whether it is a defective cell. If it is a defective cell, it is further divided into a star-shaped hidden crack defective cell, a cloud-fog defective cell, or a defective cell with both star-shaped hidden cracks and cloud-fog. According to different types, the appropriate parameter range of electric injection and laser sintering is set; then the central control system controls the supporting transmission system to transport the screened good cell to the A exit, and the bad cell is sequentially transported to the electric injection system and the laser sintering system for repair processing. Finally, the central control system performs a secondary inspection on the treated cell, specifically, electrical performance and EL tests, detects the repair effect, and outputs good cells.

[0056] Example 1

[0057] A method for processing a defective N-type TOPCon cell comprises the following steps:

[0058] (1) Providing a finished TOPCon battery; (2) Performing an electric injection treatment on the TOPCon battery to obtain an electric injection treated TOPCon battery, wherein the current is 6A and the time is 500s; (3) Performing a laser sintering treatment on the electric injection treated TOPCon battery to obtain a laser sintered TOPCon battery, wherein the laser power is 10% and the bias voltage is 36V; (4) Performing an electrical performance test and an EL test on the laser sintered TOPCon battery.

[0059] Specifically, a piece of N-type TOPCon cell is placed in the processing system of the N-type TOPCon defective cell of the present invention, and the central control system detects the placed cell and determines it as a defective cell, and further determines that the defective cell is a star-shaped hidden crack defective cell; the appropriate parameters of electric injection are set to 6A current and 500s time, and the appropriate parameters of laser sintering are 10% laser power and 36V bias voltage; the defective cell is sequentially transmitted to the electric injection system and the laser sintering system for repair processing. Finally, the central control system performs a secondary inspection on the processed cell to detect the repair effect and output the good cell.

[0060] Example 2

[0061] A method for processing a defective N-type TOPCon cell comprises the following steps:

[0062] (1) Providing a finished TOPCon battery; (2) Performing an electric injection treatment on the TOPCon battery to obtain an electric injection treated TOPCon battery, wherein the current is 6.5A and the time is 550s; (3) Performing a laser sintering treatment on the electric injection treated TOPCon battery to obtain a laser sintered TOPCon battery, wherein the laser power is 10% and the bias voltage is 36V; (4) Performing an electrical performance test and an EL test on the laser sintered TOPCon battery.

[0063] Specifically, a piece of N-type TOPCon cell is placed in the processing system of the N-type TOPCon defective cell of the present invention, and the central control system detects the placed cell, determines it as a defective cloud cell, sets the appropriate parameters of electric injection to 6.5A current and 550s time, and the appropriate parameters of laser sintering to 10% laser power and 36V bias voltage; the defective cell is sequentially transmitted to the electric injection system and the laser sintering system for repair processing. Finally, the central control system performs a secondary inspection on the processed cell to detect the repair effect and outputs the good cell.

[0064] Example 3

[0065] A method for processing a defective N-type TOPCon cell comprises the following steps:

[0066] (1) Providing a finished TOPCon battery; (2) Performing an electric injection treatment on the TOPCon battery to obtain an electric injection treated TOPCon battery, wherein the current is 8A and the time is 600s; (3) Performing a laser sintering treatment on the electric injection treated TOPCon battery to obtain a laser sintered TOPCon battery, wherein the laser power is 20% and the bias voltage is 40V; (4) Performing an electrical performance test and an EL test on the laser sintered TOPCon battery.

[0067] Specifically, a piece of N-type TOPCon cell is placed in the processing system of the N-type TOPCon defective cell of the present invention, and the central control system detects the placed cell, determines that it is a defective cell with both star-shaped hidden cracks and cloud-fog pieces, sets the appropriate parameters of electric injection to 8A current and 600s, and the appropriate parameters of laser sintering to 20% laser power and 40V bias voltage; the defective cell is sequentially transmitted to the electric injection system and the laser sintering system for repair processing. Finally, the central control system performs a secondary inspection on the processed cell to detect the repair effect and outputs the good cell.

[0068] Example 4

[0069] A method for processing a defective N-type TOPCon cell comprises the following steps:

[0070] (1) Take a plurality of TOPCon batteries that have been produced; (2) Perform an electric injection treatment on the TOPCon batteries to obtain TOPCon batteries after the electric injection treatment, with a current of 10A and a time of 900s; (3) Perform a laser sintering treatment on the TOPCon batteries after the electric injection treatment to obtain a TOPCon battery after the laser sintering treatment, wherein the laser power is 30% and the bias voltage is 50V; (4) Perform an electrical performance test and an EL test on the TOPCon batteries after the laser sintering treatment.

[0071] Specifically, multiple N-type TOPCon cells are stacked and placed in the processing system of the N-type TOPCon defective cells of the present invention. The central control system detects the placed cells, sets the appropriate parameters for electric injection to be 10A current and 900s time, and the appropriate parameters for laser sintering to be 30% laser power and 50V bias voltage; then the central control system controls the transmission system to transport the screened good cells to exit A, and transports the defective cells to the electric injection system and the laser sintering system in turn for repair. Finally, the central control system performs secondary inspection on the treated cells, specifically electrical performance and EL tests, detects the repair effect, and outputs good cells.

[0072] Example 5

[0073] A method for processing a defective N-type TOPCon cell comprises the following steps:

[0074] (1) Take a plurality of TOPCon batteries that have been produced; (2) Perform an electric injection treatment on the TOPCon batteries to obtain a TOPCon battery after the electric injection treatment, with a current of 9A and a time of 800s; (3) Perform a laser sintering treatment on the TOPCon batteries after the electric injection treatment to obtain a TOPCon battery after the laser sintering treatment, wherein the laser power is 25% and the bias voltage is 45V; (4) Perform an electrical performance test and an EL test on the TOPCon batteries after the laser sintering treatment.

[0075] Specifically, multiple N-type TOPCon cells are sequentially placed on the support conveyor in the processing system of the N-type TOPCon defective cells of the present invention, and the central control system simultaneously detects the placed cells, sets the appropriate parameters for electric injection to 9A current and 800s time, and the appropriate parameters for laser sintering to 25% laser power and 45V bias voltage; then the central control system controls the transmission system to transport the screened good cells to exit A, and sequentially transports the defective cells to the electric injection system and the laser sintering system for repair. Finally, the central control system performs secondary inspection on the processed cells, specifically electrical performance, EL test and electrical conversion rate test, detects the repair effect, and outputs the good cells.

[0076] Example 6

[0077] A TOPCon battery sheet with a star-shaped hidden crack defect is provided; the TOPCon battery is subjected to an electric injection treatment to obtain a TOPCon battery after the electric injection treatment; wherein the current and time are 5A and the time is 500s respectively; the TOPCon battery after the electric injection treatment is subjected to a laser sintering treatment to obtain a TOPCon battery after the laser sintering treatment; wherein the laser power is 10% and the bias voltage is 36V; and the TOPCon battery after the laser sintering treatment is subjected to an electrical performance test and an EL test.

[0078] Example 7

[0079] A TOPCon cell sheet with a star-shaped hidden crack defect is provided; (2) the TOPCon cell is subjected to an electric injection treatment to obtain a TOPCon cell after the electric injection treatment; wherein the current is 6A and the time is 1200s; (3) the TOPCon cell after the electric injection treatment is subjected to a laser sintering treatment to obtain a TOPCon cell after the laser sintering treatment; wherein the laser power is 10% and the bias voltage is 36V; (4) the TOPCon cell after the laser sintering treatment is subjected to an electrical performance test and an EL test.

[0080] Example 8

[0081] A TOPCon battery sheet with a star-shaped hidden crack defect is provided; the TOPCon battery is subjected to an electric injection treatment to obtain a TOPCon battery after the electric injection treatment; wherein the current and time are 6A and the time is 500s respectively; the TOPCon battery after the electric injection treatment is subjected to a laser sintering treatment to obtain a TOPCon battery after the laser sintering treatment; wherein the laser power is 35% and the bias voltage is 36V; and the TOPCon battery after the laser sintering treatment is subjected to an electrical performance test and an EL test.

[0082] Example 9

[0083] A TOPCon battery sheet with a star-shaped hidden crack defect is provided; the TOPCon battery is subjected to an electric injection treatment to obtain a TOPCon battery after the electric injection treatment; wherein the current and time are 6A and the time is 500s respectively; the TOPCon battery after the electric injection treatment is subjected to a laser sintering treatment to obtain a TOPCon battery after the laser sintering treatment; wherein the laser power is 10% and the bias voltage is 40V; and the TOPCon battery after the laser sintering treatment is subjected to an electrical performance test and an EL test.

[0084] Comparative Example 1

[0085] A defective TOPCon battery cell having both star-shaped hidden cracks and cloud flakes is provided; the TOPCon battery cell is subjected to an electric injection treatment to obtain a TOPCon battery cell after the electric injection treatment; wherein the current and time are the same as those in Example 3; and the TOPCon battery cell after the electric injection treatment is subjected to an electrical performance test and an EL test.

[0086] Comparative Example 2

[0087] A defective TOPCon cell having both star-shaped hidden cracks and cloud flakes is provided; the TOPCon cell is subjected to laser sintering treatment to obtain a TOPCon cell after laser sintering treatment; wherein the laser power and the bias voltage are the same as those in Example 3; and the TOPCon cell after laser sintering treatment is subjected to electrical performance test and EL test.

[0088] Comparative Example 3

[0089] Providing a single defective TOPCon cell with star-shaped hidden cracks; performing light injection treatment on the TOPCon cell (normal process of the production line) to obtain a TOPCon cell after light injection treatment; (3) performing laser sintering treatment on the TOPCon cell after light injection treatment to obtain a TOPCon cell after laser sintering treatment; wherein the laser power is 25% and the bias voltage is 45V; (4) performing electrical performance test and EL test on the TOPCon cell after laser sintering treatment.

[0090] Comparative Example 4

[0091] Provide a plurality of defective TOPCon battery sheets; (2) perform electrical injection treatment on the TOPCon battery to obtain a TOPCon battery after electrical injection treatment; wherein the current and time are 12A and 1200s respectively; (3) perform laser sintering treatment on the TOPCon battery after electrical injection treatment to obtain a TOPCon battery after laser sintering treatment; wherein the laser power is 35% and the bias voltage is 55V; (4) perform electrical performance test and EL test on the TOPCon battery after laser sintering treatment.

[0092] The repaired N-type TOPCon cells obtained by the methods provided in Examples 1-9 and Comparative Examples 1-4 were subjected to electrical performance tests, EL tests and photoelectric conversion efficiency tests, and the electrical performance data and photoelectric conversion efficiency obtained are shown in Table 1.

[0093] Table 1

[0094]

[0095]

[0096] From the data in Table 1 we can see that:

[0097] By comparing Examples 1-9 with Comparative Examples 1-4 and the attached specification Figure 1-20 It can be seen from the comparison that the combined process of electric injection and laser sintering of the present invention can repair star-shaped hidden crack defective sheets, cloud defective sheets and defective sheets with both defects, and can repair multiple defective sheets at the same time.

[0098] (1) From the comparison between Example 3 and Comparative Example 1, it can be seen that for a single N-type TOPCon defective wafer with both star-shaped cracks and cloud-shaped defects, only a single electrical injection cannot be performed to completely repair the defects (due to Fig.17 It can be seen that the electrical properties of the defective sheet after repair are significantly improved after the defective sheet is repaired in Example 3. The cloud sheet is caused by the poor contact between the slurry and the silicon substrate. The opening voltage, FF and contact of Example 3 will be improved, so its electrical properties will also be improved.

[0099] (2) From the comparison between Comparative Example 2 and Example 3, it can be seen that for a single N-type TOPCon defective sheet with both star-shaped microcracks and cloud-fog defects, only laser sintering repair cannot achieve complete repair of the defects, especially for the star-shaped microcrack type defect. The repair effect is particularly poor (as shown in the attached Fig.18As can be seen). In terms of the electrical performance and photoelectric conversion efficiency of the repaired defective sheet, it is obvious that the repaired cell of Example 3 has been significantly improved in all aspects. Since only laser sintering was performed, the star-shaped cracks of the cell were not well repaired. The efficiency of the cell that was only laser sintered would be slightly lower, because the small star-shaped cracks have little effect on the efficiency of the cell. Star-shaped cracks will cause the current collection capacity of the cell to decrease, and the output power of the cell to decrease; due to the decrease in current collection capacity, the overall efficiency of the cell will be affected, and it will also affect the life and reliability of the cell; therefore, the efficiency and power of the cell will be improved, and the life and reliability will be better.

[0100] (3) Comparison between Comparative Example 3 and Example 1 shows that the electric injection and laser sintering process can be used to repair a single star-shaped crack defect in the cell. The performance of the cell repaired by the electric injection and laser sintering combined repair process within the parameter range of the present invention is superior. However, the continued use of light injection and laser sintering has no effect on the repair of a single star-shaped crack defect (see the attached Fig. 20 can be seen).

[0101] (4) From the comparison of Examples 4-5, it can be seen that multiple defective sheets can be repaired simultaneously. The combined repair of electric injection and laser sintering within the parameter range of the present invention can completely repair multiple defective sheets at the same time, and the performance and photoelectric conversion rate of the repaired battery are higher. However, when the charging current is too large or the charging time is too long, it may cause plasma sputtering inside the battery, causing damage to the electrode, further affecting the life and performance of the battery. When the power of laser sintering is too large, the damage to the silicon substrate is greater, so the composite current is larger, the contact resistance will also be larger, and the efficiency of the repaired battery sheet will be affected.

[0102] (5) By comparing Examples 4-5, it can be seen that multiple defective sheets can be repaired simultaneously. The combined process of electric injection and laser sintering of the present invention can completely repair multiple defective sheets at the same time, and the repaired battery has higher electrical performance and photoelectric conversion efficiency. However, the star-shaped hidden cracks in Comparative Example 2 are still difficult to repair. For a detailed analysis, please refer to (2).

[0103] (6) From the comparison of Examples 6-9, it can be seen that within the parameter range of this patent, both defective sheets can be processed well.

[0104] (7) By comparing Comparative Example 4 with Examples 4-5, it can be seen that the star-shaped hidden crack defects of the cell can be repaired by the electric injection and laser sintering process, but the performance of the cell repaired by the electric injection and laser sintering combined repair process within the parameter range of the present invention is superior. When the cell is electrically injected at an excessively high voltage, the aging process of the battery will be accelerated, resulting in a shortened battery life; when the charging current is too large or the charging time is too long, it may cause plasma sputtering inside the battery, resulting in electrode damage, further affecting the life and performance of the battery. Electric injection injects carriers through electricity. When the voltage is too low, the number of carriers decreases. Since multiple cells are stacked together, all cells cannot be uniformly injected with carriers, and the passivation of defects by hydrogen will be reduced, so the life and performance of the battery will be reduced. However, if the bias voltage of laser sintering is too high, the solar cell will undergo reverse breakdown, making both the illuminated area and the non-illuminated area conductive. Due to the current shunting effect, the local conductive current density in the illuminated area will be greatly reduced, and the resulting Joule heat will also be reduced accordingly, resulting in an increase in the contact resistance between metal and silicon, ultimately reducing the efficiency of the solar cell. Too low a bias voltage will result in poor filling and affect the conversion efficiency of the cell.

[0105] (8) By comparing the examples and the comparative examples before and after repair, it can be found that the cloud film has the greatest impact on the efficiency of the battery cell. This is because the cloud film is mostly caused by poor sintering, so the filling will be relatively low and the contact is not good, which directly affects the opening voltage, current and filling of the battery cell. The star-shaped hidden cracked film actually has little effect on the efficiency, and mainly affects the EL of the battery cell. Therefore, the star-shaped hidden cracked battery cell can only be a Class B film.

[0106] From Table 1, it can be seen that in Examples 1, 2, 3, 4 and 5, compared with Example 1, it can be seen that the short-circuit current of Example 2 will become lower and the recombination current will become higher; electric injection injects carriers through electricity. When the voltage is too low, the number of carriers decreases. Since multiple battery cells are stacked together, all battery cells cannot be uniformly injected with carriers, and the passivation of hydrogen to defects will be reduced, so the life and performance of the battery will be reduced. Compared with Example 1, it can be seen that the series resistance and recombination current of Example 3 will increase. When the battery cell is electrically injected at an excessively high voltage, the aging process of the battery will be accelerated, resulting in a shortened battery life; when the charging current is too large or the charging time is too long, it may cause plasma sputtering inside the battery, resulting in electrode damage, further affecting the life and performance of the battery. Compared with Example 1, it can be found that the system can not only process a single defective sheet, but also process battery cells with star-shaped cracks and cloud defects at the same time, and under the same processing parameters, the efficiency is basically unchanged.

[0107] Comparative Example 1 and Example 3 are compared, and the power and bias of the battery cell are increased. When the power and bias of the laser sintering reach the critical value, it can be found that the composite current of the battery cell becomes larger, indicating that the battery may be overburned. When the bias and power exceed this critical value, the gate line will burn out.

[0108] Comparative Example 2 is compared with Example 2. The power and bias of the cell are reduced. When the power and bias of the laser sintering reach the critical value, it can be found that the opening voltage will become higher and the FF will become lower. This is because the bias is too low and the contact becomes worse; the efficiency will also decrease.

[0109] In summary, it can be found that the system has the best processing effect when the electric injection parameters are 8A and the time is 700s; the laser sintering parameters are 25% laser power and 45V bias voltage; and the electric injection parameters are 6-10A and the time is 500-900s; the laser sintering parameters are 10-30% laser power and 36-50V bias voltage, which can all process defective films well.

[0110] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for processing N-type TOPCon defective cells, characterized in that: The following steps are involved: (1) Electrical injection of N-type TOPCon defective cells; (2) Laser sintering the N-type TOPCon defective cell after processing in step (1).

2. The method for processing a defective N-type TOPCon cell according to claim 1, characterized in that: In the step (1), the current intensity of the electric injection treatment is 6A-10A, and the duration of the electric injection treatment is 500s-900s.

3. The method for processing a defective N-type TOPCon cell according to claim 1, characterized in that: In the laser sintering process in step (2), the laser power is 10%-30%, and the bias voltage is 36V-50V.

4. The method for processing a defective N-type TOPCon cell according to claim 1, characterized in that: The electrical injection step performs electrical injection on one or more TOPCon cells at the same time, and the laser sintering step performs laser sintering on one or more TOPCon cells at the same time.

5. The method for processing a defective N-type TOPCon cell according to claim 4, characterized in that: When the electrical injection step performs electrical injection on a plurality of TOPCon cells simultaneously, the plurality of TOPCon cells are stacked to form a cell stack, and a forward bias voltage is applied to the cell stack to form carrier injection.

6. The method for processing a defective N-type TOPCon cell according to claim 1, characterized in that: The N-type TOPCon defective cell is an N-type TOPCon cell with star-shaped hidden cracks and / or cloud defects.

7. A system using a method for processing N-type TOPCon defective cells according to any one of claims 1 to 6, characterized in that: The system includes an electric injection system, a laser sintering system, a support transmission system and a central control system. The support transmission system, the electric injection system and the laser sintering system are arranged in sequence, and the central control system controls the operation of the support transmission system, the electric injection system and the laser sintering system.

8. The system for processing N-type TOPCon defective cells according to claim 7, characterized in that: The control work of the central control system is that the central control system detects the N-type TOPCon battery cells to determine whether they are good or bad cells; if they are good cells, they are output as good cells and subsequent work is not started; if they are bad cells, they are determined to be star-shaped cracked cells or cloud-shaped cells or both, and the electric injection parameters and laser sintering parameters are set according to the type; the central control system controls the supporting transmission system to select and transport the N-type TOPCon battery cells to different channels and transmit them between the electric injection system and the supporting transmission system.

Images