Solar cell cutting method and application thereof

Abstract

The invention discloses a solar cell cutting method and application thereof. The passivation layer is formed after the silicon wafer is doped, so that a PN junction is not damaged, a good passivation effect on the silicon wafer is achieved, and the conversion efficiency is obviously improved; when the passivation layer and the silicon substrate are cut, the cutting is completed in two steps, so that the surface damage and heat loss of the silicon body in the cutting process of the passivation layer are reduced, and the conversion efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell cutting, and in particular to a solar cell cutting method and application thereof. Background Art

[0002] As the conversion efficiency of solar cells becomes higher and higher, reducing the efficiency loss of high-efficiency cell cutting has become a focus of attention. At present, solar cells are generally cut and split by laser ablation once or multiple times in combination with mechanical breaking technology, or laser processing induced grooves followed by direct cold and hot stress splitting technology. The treatment method of laser ablation once or multiple times will cause a certain area of ​​heat-affected zone to appear on the surface of the cell, and the surface cutting damage layer reaches 40% to 45% (relative depth); while the cold and hot stress splitting treatment method after laser processing induced grooves can solve the above problems to a certain extent, but for HJT temperature-sensitive cells, its thermal cracking temperature of about 200°C still has a certain negative impact on the damage to the battery's electrical performance. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] To this end, an embodiment of the present invention provides a solar cell cutting method and application thereof.

[0005] In a first aspect, the present invention provides a solar cell cutting method, comprising the following steps:

[0006] (a) forming a doping layer on a surface of a silicon wafer to obtain a first silicon wafer;

[0007] (b) using a first laser to cut a first groove at a set position of the first silicon wafer to obtain a second silicon wafer;

[0008] (c) providing a passivation layer and an electrode on the second silicon wafer to obtain a semi-finished crystalline silicon solar cell;

[0009] (d) using a second laser to ablate the passivation layer on the surface of the semi-finished crystalline silicon solar cell to form a second groove;

[0010] (e) Cutting the crystalline silicon layer in the second cutting groove region by using a third laser.

[0011] Furthermore, the solar cell is an N-type solar cell or a P-type solar cell.

[0012] Furthermore, the cutting is a laser scribing plus breaking method, or a laser processing induced groove followed by hot and cold stress breaking method.

[0013] Furthermore, the depth of the first groove is 1% to 15% of the thickness of the first silicon wafer.

[0014] Furthermore, the power of the first laser is 5-20W, and the wavelength is 532-1064nm.

[0015] Furthermore, the passivation layer includes a silicon oxide layer and a silicon nitride layer.

[0016] Furthermore, the depth of the second groove is not less than the thickness of the passivation layer.

[0017] Furthermore, the wavelength range of the second laser is 266-1064 nm, and the laser pulse width is femtosecond, picosecond or nanosecond.

[0018] Furthermore, the wavelength range of the third laser is 266-1064 nm, and the laser pulse width is picosecond, nanosecond, quasi-continuous, or continuous.

[0019] In a second aspect, the present invention proposes application of the method proposed in the first aspect in a solar cell.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] The present invention forms a passivation layer after doping the silicon wafer, so that the PN junction is not damaged, has a good passivation effect on the silicon wafer, and significantly improves the conversion efficiency.

[0022] The present invention divides the cutting into two steps when cutting the passivation layer and the silicon substrate, thereby reducing the damage to the silicon body surface and the heat loss during the passivation layer cutting process and improving the conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0024] Figure 1 The figure is a flow chart of the solar cell cutting method of the present invention. DETAILED DESCRIPTION

[0025] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0026] Combined with Figure 1 The present invention is specifically described. The test materials and reagents used in the following examples, unless otherwise specified, can be obtained from commercial sources.

[0027] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0028] Example 1

[0029] S1: forming a doping layer on the surface of a silicon wafer to obtain a first silicon wafer.

[0030] The silicon wafer is P-type single crystal silicon with a thickness of 200 μm and a surface doping layer of N + layer; after this step, the square resistance of the silicon wafer is 95~110Ω / sq.

[0031] S2: Use a laser with a power of 10W and a wavelength of 532nm to form a heavily doped area on the doped layer and make four laser MARK points.

[0032] S3: Using a first laser to cut a first groove at a set position of the first silicon wafer to obtain a second silicon wafer, etching to remove edge junctions, cleaning to remove PSG, and then annealing.

[0033] The power of the first laser is 10W, the wavelength is 532nm, the width of the first groove is 120μm, the depth is 12μm, the annealing temperature is 800°C, and the annealing time is 1.5h.

[0034] S4: A silicon oxide layer and a silicon nitride layer are sequentially formed on the back side of the second silicon wafer, with a total thickness of 60 nm. A silicon oxide layer and a silicon nitride layer are sequentially formed on the front side of the second silicon wafer, with a total thickness of 60 nm. Front electrodes and back electrodes are printed, and the crystalline silicon solar cell semi-finished product is obtained by firing.

[0035] S5: The surface passivation layer is ablated using a second laser (ultraviolet laser), with an ablation depth of 65 nm and a width of 50 μm.

[0036] S6: Use a third laser (green light or infrared laser) to perform laser scribing and cutting. Specifically, perform multiple scanning scribing and cutting on the silicon substrate, wherein the cutting depth is 50% of the total thickness of the silicon substrate and the width is 40 μm, and then mechanically break the wafers.

[0037] Example 2

[0038] S1: forming a doping layer on the surface of a silicon wafer to obtain a first silicon wafer.

[0039] The silicon wafer is P-type single crystal silicon with a thickness of 200 μm and a surface doping layer of N + layer; after this step, the square resistance of the silicon wafer is 95~110Ω / sq.

[0040] S2: Use a laser with a power of 10W and a wavelength of 532nm to form a heavily doped area on the doped layer and make four laser MARK points.

[0041] S3: Using a first laser to cut a first groove at a set position of the first silicon wafer to obtain a second silicon wafer, etching to remove edge junctions, cleaning to remove PSG, and then annealing.

[0042] The power of the first laser is 8W, the wavelength is 532nm, the width of the first groove is 100μm, the depth is 10μm, the annealing temperature is 800°C, and the annealing time is 1.5h.

[0043] S4: A silicon oxide layer and a silicon nitride layer are sequentially formed on the back side of the second silicon wafer, with a total thickness of 70 nm. A silicon oxide layer and a silicon nitride layer are sequentially formed on the front side of the second silicon wafer, with a total thickness of 70 nm. Front electrodes and back electrodes are printed, and the crystalline silicon solar cell semi-finished product is obtained by firing.

[0044] S5: Use the second laser (ultraviolet laser) to ablate the surface passivation layer, with an ablation depth of 80 nm and a width of 50 μm.

[0045] S6: Use a third laser (green light or infrared laser) to perform laser scribing and cutting. Specifically, perform multiple scanning scribing and cutting on the silicon substrate, wherein the cutting depth is 50% of the total thickness of the silicon substrate and the width is 40 μm, and then mechanically break the wafers.

[0046] Example 3

[0047] S1: forming a doping layer on the surface of a silicon wafer to obtain a first silicon wafer.

[0048] The silicon wafer is P-type single crystal silicon with a thickness of 200 μm and a surface doping layer of N + layer; after this step, the square resistance of the silicon wafer is 95~110Ω / sq.

[0049] S2: Use a laser with a power of 10W and a wavelength of 532nm to form a heavily doped area on the doped layer and make four laser MARK points.

[0050] S3: Using a first laser to cut a first groove at a set position of the first silicon wafer to obtain a second silicon wafer, etching to remove edge junctions, cleaning to remove PSG, and then annealing.

[0051] The power of the first laser is 10W, the wavelength is 532nm, the width of the first groove is 120μm, the depth is 12μm, the annealing temperature is 800°C, and the annealing time is 1.5h.

[0052] S4: A silicon oxide layer and a silicon nitride layer are sequentially formed on the back side of the second silicon wafer, with a total thickness of 60 nm. A silicon oxide layer and a silicon nitride layer are sequentially formed on the front side of the second silicon wafer, with a total thickness of 60 nm. Front electrodes and back electrodes are printed, and the crystalline silicon solar cell semi-finished product is obtained by firing.

[0053] S5: The surface passivation layer is ablated using a second laser (ultraviolet laser), with an ablation depth of 65 nm and a width of 50 μm.

[0054] S6: Use a third laser (green light or infrared laser) to perform laser scribing and cutting. Specifically, perform multiple scanning scribing and cutting on the silicon substrate, wherein the cutting depth is 30% of the total thickness of the silicon substrate and the width is 30 μm, and then mechanically break the wafers.

[0055] Comparative Example 1

[0056] S1: forming a doping layer on the surface of a silicon wafer to obtain a first silicon wafer.

[0057] The silicon wafer is P-type single crystal silicon with a thickness of 200 μm and a surface doping layer of N + layer; after this step, the square resistance of the silicon wafer is 95~110Ω / sq.

[0058] S2: Use a laser with a power of 10W and a wavelength of 532nm to form a heavily doped area on the doped layer and make four laser MARK points.

[0059] S3: Using a first laser to cut a first groove at a set position of the first silicon wafer to obtain a second silicon wafer, etching to remove edge junctions, cleaning to remove PSG, and then annealing.

[0060] The power of the first laser is 10W, the wavelength is 532nm, the width of the first groove is 120μm, the depth is 12μm, the annealing temperature is 800°C, and the annealing time is 1.5h.

[0061] S4: A silicon oxide layer and a silicon nitride layer are sequentially formed on the back side of the second silicon wafer, with a total thickness of 60 nm. A silicon oxide layer and a silicon nitride layer are sequentially formed on the front side of the second silicon wafer, with a total thickness of 60 nm. Front electrodes and back electrodes are printed, and the crystalline silicon solar cell semi-finished product is obtained by firing.

[0062] S5: Use a third laser (green light or infrared laser) to perform laser scribing and cutting. Specifically, perform multiple scanning scribing and cutting on the silicon substrate, wherein the cutting depth is 50% of the total thickness of the silicon substrate and the width is 40 μm, and then mechanically break the wafers.

[0063] The efficiency of the solar cell slices of Examples 1 to 3 and Comparative Example 1 was measured, and the test results are shown in Table 1.

[0064] Example 1 Example 2 Example 3 Comparative Example 1 Conversion efficiency 23.56％ 23.36％ 23.13％ 22.37％

[0065] It can be seen from Table 1 that, compared with the comparative example, the efficiency of the solar cell slices prepared in Examples 1 to 3 of the present invention is greater than that in Comparative Example 1. It can be seen that, in the process of cutting the passivation layer and the silicon body, the present invention uses a two-step cutting method and adopts appropriate laser parameters for the passivation layer, thereby reducing the surface damage and heat loss of the silicon body during the passivation layer cutting process and improving the conversion efficiency.

[0066] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms may be for different embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0067] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0068] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for cutting a solar cell, characterized in that: The following steps are involved: (a) forming a doping layer on a surface of a silicon wafer to obtain a first silicon wafer; (b) using a first laser to cut a first groove at a set position of the first silicon wafer to obtain a second silicon wafer; (c) providing a passivation layer and an electrode on the second silicon wafer to obtain a semi-finished crystalline silicon solar cell; (d) using a second laser to ablate the passivation layer on the surface of the semi-finished crystalline silicon solar cell to form a second groove; (e) Cutting the crystalline silicon layer in the second cutting groove region by using a third laser.

2. The method according to claim 1, characterized in that The solar cell is an N-type solar cell or a P-type solar cell.

3. The method according to claim 1, characterized in that The cutting is performed by laser scribing and breaking, or by laser processing to induce grooves followed by cold or hot stress breaking.

4. The method according to claim 1, characterized in that The depth of the first groove is 1% to 15% of the thickness of the first silicon wafer.

5. The method according to claim 1, characterized in that The power of the first laser is 5-20W, and the wavelength is 532-1064nm.

6. The method according to claim 1, characterized in that The passivation layer includes a silicon oxide layer and a silicon nitride layer.

7. The method according to claim 1, characterized in that The depth of the second groove is not less than the thickness of the passivation layer.

8. The method according to claim 1, characterized in that The wavelength range of the second laser is 266-1064 nm, and the laser pulse width is femtosecond, picosecond or nanosecond.

9. The method according to claim 1, characterized in that The wavelength range of the third laser is 266-1064 nm, and the laser pulse width is picosecond, nanosecond, quasi-continuous, or continuous.

10. Use of the method according to any one of claims 1 to 9 in solar cells.

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