Method for treating leakage at edge of solar cell after electroplating and depositing metal electrode, and solar cell

Abstract

The present invention provides a method for processing leakage at the edge of a solar cell after electroplating and depositing a metal electrode, and a solar cell, and relates to the technical field of photovoltaic cells. The above-mentioned processing method sequentially performs thermal annealing and plasma bombardment treatment on the side of the crystalline silicon substrate of the solar cell after electroplating and depositing the metal electrode, so that the metal coating grown on the side of the crystalline silicon substrate during electroplating falls off, thereby avoiding the problem of leakage at the edge of the battery. Therefore, the processing method of the present application can remove the metal coating grown on the side of the crystalline silicon substrate after electroplating and depositing metal without consuming any chemical products during the processing process, effectively alleviating the technical problem of leakage at the edge of the existing solar cell, and compared with the existing chemical corrosion and side masking methods, it has the advantages of strong economy and environmental friendliness.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, and in particular to a method for processing leakage at the edge of a solar cell after electroplating and depositing a metal electrode, and a solar cell. Background Art

[0002] In recent years, with the continuous expansion of photovoltaic production capacity, the demand for silver will increase in the future. Since the solar metallization method using nickel, copper and other metal electroplating or light-induced electroplating to replace silver paste screen printing can greatly reduce the demand for silver in solar cell manufacturing, the electroplating metallization scheme based on nickel, copper and other metals has great potential.

[0003] However, currently when metal is electroplated on crystalline silicon cells, a metal coating will grow on the edge sides of the silicon substrate due to the presence of a conductive layer or the thinning or loss of the passivation film layer after corrosion, causing battery leakage. The existing technology generally uses chemical corrosion methods to remove the metal coating on the edge sides, or applies a mask to the sides for protection to avoid the growth of the metal coating. However, such methods require the consumption of a large amount of chemicals, generate various types of chemical waste, and increase production costs.

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

[0005] The first purpose of the present invention is to provide a method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode. The method can remove the metal coating grown on the side of a crystalline silicon substrate after electroplating and depositing metal without consuming any chemical products during the treatment process, thereby alleviating the technical problem of leakage at the edge of the cell.

[0006] The second object of the present invention is to provide a solar cell, which is obtained by using the above-mentioned solar cell edge leakage treatment method after electroplating and depositing metal electrodes.

[0007] A third object of the present invention is to provide a solar cell module.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] The present invention provides a method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode, the method comprising:

[0010] A solar cell crystalline silicon substrate after electroplating metal electrodes is provided, and then the side of the crystalline silicon substrate is subjected to thermal annealing and plasma bombardment in sequence to cause the metal coating grown on the side of the crystalline silicon substrate during electroplating to fall off.

[0011] Furthermore, the thermal annealing is performed by irradiating an infrared heating lamp.

[0012] Furthermore, the thermal annealing temperature is 80-150° C., the annealing time is 30-120 s, and the annealing heating rate is 10-25° C. / s.

[0013] Furthermore, the plasma bombardment is a purge treatment using low-temperature plasma.

[0014] Furthermore, the plasma temperature of the low-temperature plasma sweep is 20-50°C.

[0015] Furthermore, the plasma gas source of the low-temperature plasma sweep includes at least one of nitrogen and argon.

[0016] Furthermore, the low-temperature plasma sweeping speed is 0.5-2 m / min.

[0017] Furthermore, the processing method includes:

[0018] (A) After electroplating and depositing metal electrodes, the crystalline silicon substrates of solar cells are neatly stacked up and down, and the sides are completely aligned to form plane A;

[0019] Using infrared heating lamps to irradiate plane A for thermal annealing;

[0020] The thermal annealing temperature is 80-150°C, the annealing time is 30-120s, and the annealing heating rate is 10-25°C / s;

[0021] (B) using low temperature plasma to purge the plane A after being treated in step (A);

[0022] The temperature of the low-temperature plasma is 20-50° C., the sweeping speed of the low-temperature plasma is 0.5-2 m / min, and the plasma gas source of the low-temperature plasma sweeping includes at least one of nitrogen and argon.

[0023] The present invention provides a solar cell, which is obtained by electroplating and depositing a metal electrode and then using the above-mentioned solar cell edge leakage treatment method.

[0024] The present invention provides a solar cell assembly, which comprises the above-mentioned solar cell.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present application provides a method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode. The method sequentially performs thermal annealing and plasma bombardment on the side of a crystalline silicon substrate of a solar cell after electroplating and depositing a metal electrode, thereby causing the metal coating grown on the side of the crystalline silicon substrate during electroplating to fall off.

[0027] Compared with the existing methods of solving the leakage problem of solar cell edges after electroplating and depositing metal electrodes, such as chemical etching and side masking. The present application provides a completely different solution. First, the hydrogen in the metal coating grown on the side of the substrate is released by heat treatment, and the metal coating tends to shrink, thereby generating tensile stress on its surface, which destroys the reliability of the contact between the metal coating and the silicon substrate. Then, plasma is used to bombard the metal coating grown on the side of the substrate. Since the plasma energy is much higher than that of ordinary gas molecules, it will bombard and etch the metal coating, thereby separating the metal coating from the side of the silicon substrate, solving the problem of solar cell leakage. Therefore, the present application does not use any chemical products in the processing process to remove the metal coating grown on the side of the crystalline silicon substrate during electroplating, which has the advantages of strong economy and environmental friendliness.

[0028] The solar cell provided by the present invention is obtained by using the above-mentioned solar cell edge leakage treatment method after electroplating and depositing metal electrodes. Determined by the above-mentioned treatment method, the solar cell effectively alleviates the edge leakage problem of the battery and improves the conversion efficiency of the battery.

[0029] The solar cell assembly provided by the present invention comprises the above-mentioned solar cell and has the technical advantage of high cell conversion efficiency. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0031] According to one aspect of the present invention, a method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode comprises:

[0032] A solar cell crystalline silicon substrate after electroplating metal electrodes is provided, and then the side of the crystalline silicon substrate is subjected to thermal annealing and plasma bombardment in sequence to cause the metal coating grown on the side of the crystalline silicon substrate during electroplating to fall off.

[0033] The present application provides a method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode. The method sequentially performs thermal annealing and plasma bombardment on the side of a crystalline silicon substrate of a solar cell after electroplating and depositing a metal electrode, thereby causing the metal coating grown on the side of the crystalline silicon substrate during electroplating to fall off.

[0034] Compared with the existing methods for solving the leakage problem at the edge of solar cells after electroplating and depositing metal electrodes, such as chemical corrosion and side masking. The present application provides a completely different solution. First, the hydrogen in the metal coating grown on the side of the substrate is released by heat treatment, and the metal coating tends to shrink, thereby generating tensile stress on its surface, destroying the reliability of the contact between the metal coating and the silicon substrate; then, plasma is used to bombard the metal coating grown on the side of the substrate. Since the plasma energy is much higher than that of ordinary gas molecules, it will bombard and etch the metal coating, thereby separating the metal coating from the side of the silicon substrate, solving the problem of leakage of solar cells. Therefore, the present application does not use any chemical products in the processing process, and has the advantages of strong economy and environmental friendliness.

[0035] In a preferred embodiment of the present invention, the thermal annealing is performed by irradiating an infrared heating lamp.

[0036] As a preferred embodiment, the infrared heating lamp heats the object through infrared radiation. The metal has a higher infrared absorption rate than the silicon substrate, and the heating rate is higher than the silicon substrate. The temperature difference and expansion coefficient difference between the metal and the silicon substrate further destroy the reliability of the edge bonding between the copper and the silicon substrate.

[0037] In a preferred embodiment of the present invention, the thermal annealing temperature is 80-150° C., the annealing time is 30-120 s, and the annealing heating rate is 10-25° C. / s.

[0038] As a preferred embodiment, the thermal annealing temperature is higher than 150°C or the time exceeds 120s, and the heat is transferred from the edge to the center of the silicon wafer, affecting the performance of the metal electrode in the center area; the temperature is lower than 80°C or the time is less than 30s, and the overall heat is low, which is not enough to completely destroy the reliability of the bonding between copper and the edge of the silicon substrate.

[0039] In a preferred embodiment of the present invention, the plasma bombardment is a purge treatment using low-temperature plasma.

[0040] In the above preferred embodiment, the plasma temperature of the low-temperature plasma sweep is 20-50°C.

[0041] As a preferred implementation, the electrons in the low-temperature plasma have the high energy characteristic of plasma, while the positive ion radicals have low energy and bombard the silicon substrate without causing damage to the silicon substrate.

[0042] In the above preferred embodiment, the plasma gas source of the low-temperature plasma sweep includes at least one of nitrogen and argon.

[0043] In the above preferred embodiment, the speed of the low-temperature plasma sweep is 0.5-2 m / min.

[0044] In a preferred embodiment of the present invention, the processing method comprises:

[0045] (A) After electroplating and depositing metal electrodes, the crystalline silicon substrates of solar cells are neatly stacked up and down, and the sides are completely aligned to form plane A;

[0046] Using infrared heating lamps to irradiate plane A for thermal annealing;

[0047] The thermal annealing temperature is 80-150°C, the annealing time is 30-120s, and the annealing heating rate is 10-25°C / s;

[0048] (B) using low temperature plasma to purge the plane A after being treated in step (A);

[0049] The temperature of the low-temperature plasma is 20-50° C., the sweeping speed of the low-temperature plasma is 0.5-2 m / min, and the plasma gas source of the low-temperature plasma sweeping includes at least one of nitrogen and argon.

[0050] According to one aspect of the present invention, a solar cell is provided, wherein the solar cell is processed by the above-mentioned method for processing edge leakage of a solar cell after a metal electrode is deposited by electroplating.

[0051] The solar cell provided by the present invention is obtained by using the above-mentioned solar cell edge leakage treatment method after electroplating and depositing metal electrodes. Determined by the above-mentioned treatment method, the solar cell effectively solves the edge leakage problem and improves the conversion efficiency of the cell.

[0052] According to one aspect of the present invention, a solar cell module comprises the above-mentioned solar cell.

[0053] The solar cell assembly provided by the present invention comprises the above-mentioned solar cell and has the technical advantage of high cell conversion efficiency.

[0054] The technical solution of the present invention will be further described below in conjunction with embodiments.

[0055] Note: The following examples and comparative examples of this application all use the same batch of solar cell crystalline silicon substrates after electroplating and depositing metal electrodes. Their raw materials, specifications and performance parameters are at the same level. Their pre-treatment processes can be referred to as follows:

[0056] (1) laser opening is performed on a designated area of ​​the passivation anti-reflection film on the surface of the silicon substrate to form a patterned area of ​​exposed silicon;

[0057] (2) Pre-cleaning the patterned silicon substrate to remove the passivation anti-reflection film residue and the oxide layer remaining on the surface of the patterned area;

[0058] (3) immersing the cleaned silicon substrate in a nickel electroplating solution for electroplating to deposit a nickel metal layer in the patterned area;

[0059] (4) placing the silicon substrate after the nickel metal layer is deposited into a copper electroplating solution to deposit a copper metal layer on the nickel metal layer;

[0060] Meanwhile, it should be noted that, unless otherwise specified in the embodiments and comparative examples of the present invention, the parameters conventionally used in the art may be used, and the parameters not otherwise specified in the embodiments and comparative examples are at the same level.

[0061] Example 1

[0062] A method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode, comprising the following steps:

[0063] (1) Providing solar cell crystalline silicon substrates after electroplating and depositing metal electrodes, and then neatly stacking the solar cell crystalline silicon substrates up and down, and completely aligning the sides to form a plane A;

[0064] (2) Using an infrared heating lamp to irradiate plane A for thermal annealing;

[0065] The thermal annealing temperature is 100°C, the annealing time is 80s, and the annealing heating rate is 20°C / s;

[0066] (3) Use low-temperature plasma to purge the plane A after annealing in step (2) for 15s to 25s to make the metal coating fall off from the side of the silicon substrate.

[0067] The temperature of the low-temperature plasma is 35° C., the sweep speed of the low-temperature plasma is 1 m / min, and the plasma gas source of the low-temperature plasma sweep includes at least one of nitrogen and argon.

[0068] Example 2

[0069] A method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode, comprising the following steps:

[0070] (1) Same as in Example 1;

[0071] (2) Using an infrared heating lamp to irradiate plane A for thermal annealing;

[0072] The thermal annealing temperature is 150°C, the annealing time is 120s, and the annealing heating rate is 10°C / s;

[0073] (3) Same as Example 1.

[0074] Example 3

[0075] A method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode, comprising the following steps:

[0076] (1) Same as in Example 1;

[0077] (2) Using an infrared heating lamp to irradiate plane A for thermal annealing;

[0078] The thermal annealing temperature is 80°C, the annealing time is 30s, and the annealing heating rate is 25°C / s;

[0079] (3) Same as Example 1.

[0080] Example 4

[0081] A method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode, comprising the following steps:

[0082] (1) Same as in Example 1;

[0083] (2) Same as in Example 1;

[0084] (3) Use low-temperature plasma to purge the plane A after annealing in step (2) for 15s to 25s, so that the metal coating falls off from the side of the silicon substrate.

[0085] The temperature of the low-temperature plasma is 20°C, and the sweeping speed of the low-temperature plasma is 0.5 m / min;

[0086] The plasma gas source of the low-temperature plasma sweep is nitrogen.

[0087] Example 5

[0088] A method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode, comprising the following steps:

[0089] (1) Same as in Example 1;

[0090] (2) Same as in Example 1;

[0091] (3) Use low-temperature plasma to purge the plane A after annealing in step (2) for 15s to 25s to make the metal coating fall off from the side of the silicon substrate.

[0092] The temperature of the low-temperature plasma is 50°C, and the sweeping speed of the low-temperature plasma is 2m / min;

[0093] The plasma gas source of the low-temperature plasma sweep is nitrogen.

[0094] Example 6

[0095] This embodiment is the same as Embodiment 1 except that the thermal annealing temperature in step (2) is 180°C.

[0096] Example 7

[0097] This embodiment is the same as Embodiment 1 except that the thermal annealing temperature in step (2) is 70°C.

[0098] Example 8

[0099] This embodiment is the same as Embodiment 1 except that the thermal annealing time in step (2) is 150 seconds.

[0100] Example 9

[0101] This embodiment is the same as Embodiment 1 except that the thermal annealing time in step (2) is 20 seconds.

[0102] Example 10

[0103] This embodiment is the same as Embodiment 1 except that the plasma temperature in step (3) is 80°C.

[0104] Embodiment 11

[0105] This embodiment is the same as Embodiment 1 except that the plasma temperature in step (3) is 60°C.

[0106] Example 12

[0107] This embodiment is the same as Embodiment 1 except that the speed of the low-temperature plasma sweep in step (3) is 2.5 m / min.

[0108] Comparative Example 1

[0109] A method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode, comprising the following steps:

[0110] (1) Providing solar cell crystalline silicon substrates after electroplating and depositing metal electrodes, and then neatly stacking the solar cell crystalline silicon substrates up and down, and completely aligning the sides to form a plane A;

[0111] (2) Use infrared heating lamps to irradiate plane A for thermal annealing to complete the treatment.

[0112] The thermal annealing temperature is 100° C., the annealing time is 80 seconds, and the annealing heating rate is 20° C. / s.

[0113] The difference between this comparative example and Example 1 is that this comparative example does not include the step of low-temperature plasma.

[0114] Comparative Example 2

[0115] A method for treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode, comprising the following steps:

[0116] (1) Providing solar cell crystalline silicon substrates after electroplating and depositing metal electrodes, and then neatly stacking the solar cell crystalline silicon substrates up and down, and completely aligning the sides to form a plane A;

[0117] (2) Use low-temperature plasma to purge and process plane A.

[0118] The temperature of the low-temperature plasma is 35° C., the sweep speed of the low-temperature plasma is 1 m / min, and the plasma gas source of the low-temperature plasma sweep includes at least one of nitrogen and argon.

[0119] The difference between this comparative example and Example 1 is that this comparative example does not include a heat treatment step before the low-temperature plasma is purged on the plane A. It has been verified that after purging for 10 minutes, it is found that the metal coating cannot be peeled off from the side of the silicon substrate.

[0120] Test Example 1

[0121] The solar cells prepared by the treatment methods of the above-mentioned Examples 1 to 12 and Comparative Examples 1 and 2 were subjected to IV testing to detect the conversion efficiency of the solar cells and the leakage current under a reverse voltage of -12V; at the same time, the solar cell crystalline silicon substrate after the electroplating deposition of the metal electrode without treatment in Example 1 was provided as a control group 1;

[0122] A crystalline silicon substrate for solar cells prepared by the existing scheme of "applying a mask on the side for protection to avoid the growth of a metal coating" is provided as a control group 2;

[0123] A conventional solution of chemically etching the "crystalline silicon substrate of a solar cell after electroplating and depositing a metal electrode" to remove the metal coating on the edge side is provided as a control group 3 and compared with the technical solution of the present application.

[0124] The specific detection methods are as follows:

[0125] At a temperature of 25°C and a light intensity of 1000W / m 2 , the spectrum meets the AM1.5 condition, and the solar cell IV tester is used to test the cell conversion efficiency Eta and the leakage current Irev2 under the reverse voltage of -12V;

[0126] The specific test results are as follows:

[0127]

[0128]

[0129] From the above results, it can be seen that after being treated by the method for treating edge leakage of solar cells after electroplating and depositing metal electrodes according to the present application, the problem of edge leakage is alleviated. Compared with the untreated crystalline silicon substrate of the solar cell after electroplating and depositing metal electrodes in the control group 1, the output power of the battery can be effectively improved, thereby obtaining a solar cell with higher conversion efficiency.

[0130] However, the silicon wafers prepared in Comparative Example 1 that do not include the low-temperature plasma step and the silicon wafers prepared in Comparative Example 2 that do not include the heat treatment step have a higher leakage current Irev2, indicating that there is still a serious battery cell leakage problem.

[0131] In addition, compared with the solar cell crystalline silicon substrates prepared by the existing methods of control group 2 and control group 3, the present application can achieve the corresponding equivalent level of cell conversion efficiency, indicating that the present application can remove the metal coating grown on the side of the crystalline silicon substrate during electroplating without using any chemical products in the processing process, which has the advantages of strong economy and environmental friendliness compared to the existing technology.

[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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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 treating leakage at the edge of a solar cell after electroplating and depositing a metal electrode, characterized in that: The processing method comprises: Providing a solar cell crystalline silicon substrate after electroplating metal electrodes, and then sequentially performing thermal annealing and plasma bombardment on the side of the crystalline silicon substrate to cause the metal coating grown on the side of the crystalline silicon substrate during electroplating to fall off; The thermal annealing temperature is 80-150° C., and the thermal annealing time is 30-120 seconds; The plasma bombardment is a sweeping treatment using low-temperature plasma, the plasma temperature of the low-temperature plasma sweeping is 20-50° C., and the speed of the low-temperature plasma sweeping is 0.5-2 m / min.

2. The processing method according to claim 1, characterized in that: The thermal annealing is performed by irradiating an infrared heating lamp.

3. The processing method according to claim 1, characterized in that: The heating rate of the thermal annealing is 10-25°C / s.

4. The processing method according to claim 1, characterized in that: The plasma gas source of the low-temperature plasma purge includes at least one of nitrogen and argon.

5. The processing method according to claim 1, characterized in that: The processing method comprises: (A) The solar cell crystalline silicon substrates after electroplating and depositing metal electrodes are neatly stacked up and down, and the sides are completely aligned to form plane A; Using infrared heating lamps to irradiate plane A for thermal annealing; The thermal annealing temperature is 80-150°C, the thermal annealing time is 30-120s, and the thermal annealing heating rate is 10-25°C / s; (B) Using low-temperature plasma to purge the plane A after being treated in step (A); The temperature of the low-temperature plasma is 20-50° C., the sweeping speed of the low-temperature plasma is 0.5-2 m / min, and the plasma gas source of the low-temperature plasma sweeping includes at least one of nitrogen and argon.

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