Preparation method of solar cell, solar cell and electric equipment

Abstract

The invention provides a preparation method of a solar cell, the solar cell and electric equipment. The method comprises the following steps: carrying out laser grooving treatment on an electrode printing area in a first surface of a target silicon wafer to obtain a first groove; determining at least two straight lines intersecting with the first groove; the at least two straight lines intersect with the first groove and have a common intersection point; according to the at least two straight lines, determining a secondary laser grooving pattern corresponding to the target silicon wafer; according to the secondary laser grooving pattern, secondary laser grooving treatment is conducted on the electrode printing area, and a second groove is obtained; the second groove is only intersected with one first groove; and preparing a target solar cell based on the target silicon wafer subjected to the secondary laser grooving treatment. According to the embodiment of the invention, the ohmic contact between the heavily doped region and the electrode of the target silicon wafer under the condition of printing offset can be improved, and the photoelectric conversion efficiency of the target solar cell is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy, and particularly to a method for preparing a solar cell, a solar cell, and an electrical device. Background Art

[0002] A selective emitter (SE) solar cell is a cell in which heavy doping is performed at the contact part between the electrode and the silicon wafer, and light doping is performed between the electrodes. The doping method of the selective emitter solar cell can reduce the recombination of the diffusion layer, reduce the contact resistance between the electrode and the silicon wafer, and improve the photoelectric conversion efficiency of the cell.

[0003] Currently, the method for preparing a selective emitter solar cell is mainly to perform laser grooving on the basis of a first light diffusion, so that a heavily doped region is formed in the laser grooving region, and a lightly doped region is formed in the remaining regions. Finally, electrode fine grids are printed in the laser grooving region, so that an ohmic contact is formed between the electrode fine grids and the heavily doped region.

[0004] However, in the related art, there is a one-to-one correspondence between the laser grooving and the electrode fine grids. During the process of printing the electrode fine grids, it is necessary to ensure that the printed electrode fine grids completely fall into the laser grooving region to ensure a good ohmic contact between the electrode fine grids and the heavily doped region. In the actual production process, due to the accuracy problems of the printing camera and the printing machine itself, printing alignment deviation will occur, and the printed fine grid lines do not all fall into the laser grooving during the printing process, resulting in a poor ohmic contact between the heavily doped region and the electrode, and further reducing the photoelectric conversion efficiency of the solar cell prepared based on the silicon wafer. Summary of the Invention

[0005] The present invention provides a method for preparing a solar cell, a solar cell, and an electrical device to solve the problems in the related art that during the preparation of a selective emitter solar cell, due to electrode printing deviation, the ohmic contact between the heavily doped region and the electrode is poor, and the photoelectric conversion efficiency of the solar cell is reduced.

[0006] To solve the above problems, the technical solution of the present invention is realized as follows:

[0007] An embodiment of the present invention provides a method for preparing a solar cell, the method including:

[0008] Obtaining a target silicon wafer, where the target silicon wafer is a silicon wafer after a first boron diffusion treatment;

[0009] Performing laser grooving treatment on an electrode printing region in a first surface of the target silicon wafer to obtain a first groove; the first surface is the surface of the target silicon wafer after the first boron diffusion treatment; the electrode printing region corresponds to the electrode to be printed one by one;

[0010] Determine at least two lines that intersect the first groove; the at least two lines intersect the first groove and have a common intersection point;

[0011] Determine the secondary laser grooving pattern corresponding to the target silicon wafer according to the at least two lines;

[0012] Perform secondary laser grooving on the electrode printing area according to the secondary laser grooving pattern to obtain a second groove; the second groove intersects only one of the first grooves;

[0013] Fabricate a target solar cell based on the target silicon wafer that has undergone secondary laser grooving.

[0014] Optionally, the performing secondary laser grooving on the electrode printing area according to the secondary laser grooving pattern to obtain a second groove includes:

[0015] Perform secondary laser grooving on at least two electrode printing areas in the first surface of the target silicon wafer that are close to the first edge of the target silicon wafer according to the secondary laser grooving pattern to obtain a second groove;

[0016] Wherein, the first edge is the edge of the target silicon wafer that is parallel to the first groove.

[0017] Optionally, a first line formed by the intersection point and the center point of the target silicon wafer is perpendicular to a second line that is parallel to the first groove.

[0018] Optionally, when the secondary laser grooving pattern includes two lines, the minimum included angle between the second groove and the first groove is 1.5° to 2.5°.

[0019] Optionally, when the number of lines in the secondary laser grooving pattern is greater than 2, the minimum included angle between the second groove and the first groove is 0.5° to 1.5°.

[0020] Optionally, before performing laser grooving on the electrode printing area in the first surface of the target silicon wafer to obtain the first groove, the method further includes:

[0021] Determine at least one electrode printing area in the first surface of the target silicon wafer according to the printing position corresponding to the electrode to be printed.

[0022] Optionally, the width of the first groove and / or the second groove is 70μm to 90μm.

[0023] Optionally, the width of the electrode to be printed is 35μm to 45μm.

[0024] An embodiment of the present invention further provides a solar cell, which is prepared by using the preparation method of the solar cell described in any one of the above.

[0025] An embodiment of the present invention further provides an electrical device, which includes the solar cell described above, and the solar cell serves as a power supply of the electrical device.

[0026] In the preparation method of the solar cell provided by the embodiment of the present invention, a first groove corresponding to each electrode to be printed is obtained by performing laser grooving on the electrode printing area in the first surface of the target silicon wafer after a first boron diffusion treatment, and a secondary laser grooving pattern corresponding to the target silicon wafer is determined according to at least two straight lines that intersect the first groove and have a common intersection point; then, the electrode printing area in the first surface is subjected to secondary laser grooving according to the secondary laser grooving pattern to obtain a second groove, so that the first surface of the target silicon wafer after the secondary laser grooving treatment includes the first groove and the second groove intersecting the first groove; during the process of printing the electrode, in the case where the printed electrode paste cannot completely fall into the first groove due to the accuracy of the printing camera and the accuracy of the printing machine table, some or all of the electrode paste that does not fall into the first groove will fall into the second groove and form an ohmic contact with the second groove, reducing the electrode loss caused by printing deviation, improving the ohmic contact between the heavily doped area of the target silicon wafer and the electrode in the case of printing deviation, and improving the photoelectric conversion efficiency of the target solar cell prepared based on the target silicon wafer after the secondary laser grooving treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings without creative efforts based on these drawings.

[0028] Figure 1 Shows a flowchart of the steps of a preparation method of a solar cell according to an embodiment of the present invention;

[0029] Figure 2 Shows a schematic diagram of printing deviation according to an embodiment of the present invention;

[0030] Figure 3 Shows a schematic diagram of the relationship between a first groove and at least two straight lines intersecting the first groove according to an embodiment of the present invention;

[0031] Figure 4 Shows a schematic diagram of a target silicon wafer after secondary laser grooving treatment according to an embodiment of the present invention. Detailed implementation manners

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0033] Refer to Figure 1 , which shows a step flow chart of a preparation method of a solar cell provided by an embodiment of the present invention. The method includes steps S110 to S160:

[0034] Step S110: Obtain a target silicon wafer, and the target silicon wafer is a silicon wafer after one-time boron diffusion treatment.

[0035] Among them, the target silicon wafer can be an N-type silicon wafer, and the N-type silicon wafer includes a first surface and a second surface. Specifically, before performing boron diffusion treatment on the N-type silicon wafer, first perform double-sided texturing on the N-type silicon wafer, and perform boron diffusion treatment on the textured first surface of the N-type silicon wafer to obtain the target silicon wafer.

[0036] In the embodiment of the present invention, a trough texturing method can be adopted to perform texturing treatment on the first surface and the second surface of the N-type silicon wafer by using a texturing solution. Among them, the texturing solution can be a sodium hydroxide solution or a potassium hydroxide solution. In the texturing solution, the proportion of the sodium hydroxide solution or the potassium hydroxide solution is 1% to 3%, and the proportion of the texturing additive is 0.45% to 0.65%. The texturing additive includes deionized water, a surfactant, sodium polystyrene sulfonate, a defoaming agent, and other chemical components. Among them, the proportion of deionized water in the texturing additive is 84%, the proportion of the surfactant in the texturing additive is 4%, the proportion of sodium polystyrene sulfonate in the texturing additive is 5%, the proportion of the defoaming agent in the texturing additive is 2%, and the proportion of other chemical components in the texturing additive is 5%. It should be noted that the proportion in the embodiment of the present invention can be a mass proportion or a volume proportion, and the embodiment of the present invention does not make a specific limitation on this.

[0037] After performing double-sided texturing on the N-type silicon wafer, boron diffusion treatment can be performed on the textured first surface of the N-type silicon wafer in a diffusion furnace. The diffusion furnace cavity is in a vacuum environment. By introducing a boron source into the diffusion furnace cavity, the boron (B) element in the boron source enters the surface layer of the first surface as a doping element to form a P-type lightly doped emitter layer, and the target silicon wafer is obtained. It should be noted that when boron diffusion treatment is performed on the first surface to obtain the emitter layer, the boron source will also diffuse around to the second surface of the target silicon wafer and form a diffusion-around emitter layer on the second surface. The diffusion-around emitter layer can be removed by polishing treatment, which will not be elaborated here.

[0038] Step S120: Perform laser grooving on the electrode printing area in the first surface of the target silicon wafer to obtain a first groove.

[0039] Wherein, the first surface is the surface of the target silicon wafer after one-time boron diffusion treatment; the electrode printing areas correspond one-to-one to the electrodes to be printed.

[0040] The electrode printing area is the area in the first surface corresponding to the electrode to be printed. For a selective emitter solar cell, before printing the electrode in the electrode printing area, it is necessary to first perform laser grooving on the electrode printing area to form a P-type heavily doped region in the electrode printing area, that is, the first groove. The other areas in the first surface outside the first groove are P-type lightly doped regions. In the existing preparation method of selective emitter solar cells, the electrode paste corresponding to the electrode to be printed can be printed into the first groove and through a sintering process, an ohmic contact is formed between the electrode and the P-type heavily doped region.

[0041] Wherein, during the process of performing laser grooving on the electrode printing area, the grooved area formed by laser melting is the first groove, and the grooving depth of the first groove can be 1.4 μm.

[0042] It can be understood that the number of electrode printing areas is the same as the number of electrodes to be printed, and the electrode printing areas and the electrodes to be printed correspond one-to-one.

[0043] Step S130: Determine at least two straight lines intersecting with the first groove; the at least two straight lines intersect with the first groove and have a common intersection point.

[0044] Step S140: Determine the secondary laser grooving pattern corresponding to the target silicon wafer according to the at least two straight lines.

[0045] Step S150: Perform secondary laser grooving on the electrode printing area according to the secondary laser grooving pattern to obtain a second groove; the second groove intersects with only one of the first grooves.

[0046] In the embodiment of the present invention, considering that in the actual production process, due to the problems of the printing camera accuracy and the accuracy of the printing machine itself, printing deviation will occur during the printing process. The printing deviation is usually a clockwise rotation deviation and a counterclockwise rotation deviation centered on the center point of the target silicon wafer, resulting in that the electrode paste corresponding to the electrode to be printed cannot all fall into the first groove, causing electrode loss, and making the ohmic contact between the P-type heavily doped region and the electrode in the solar cell poor. Refer to Figure 2 , which shows a schematic diagram of printing deviation provided by the embodiment of the present invention. As shown in Figure 2As shown, during the process of printing electrodes on the electrode printing area of the target silicon wafer 10, a clockwise rotational offset centered on the center point 02 of the target silicon wafer 10 occurred, and only a small part of the printed electrode paste fell into the first groove 11, resulting in serious electrode loss.

[0047] Based on this, in the embodiment of the present invention, first, at least two straight lines that intersect the first groove and have a common intersection point are determined through step S130. It can be understood that when at least two straight lines intersect the first groove and there is only one common intersection point, each straight line is distributed on both sides of the first groove centered on this intersection point. When the first groove is rotated counterclockwise or clockwise, the first groove can coincide with any one of the at least two straight lines determined in step S130.

[0048] Among them, the first groove in step S130 can be any one of the first grooves obtained through step S120. When it is necessary to perform secondary laser grooving processing on each electrode printing area on the first surface in step S150, step S130 can be repeatedly executed to sequentially determine at least two straight lines that intersect the first groove in each electrode printing area, and a straight line group corresponding to each electrode printing area is obtained; each electrode printing area on the first surface corresponds to a group of straight lines, and the straight line group corresponding to each electrode printing area is composed of at least two straight lines that intersect the first groove in this electrode printing area and have a common intersection point. When it is only necessary to perform secondary laser grooving processing on some electrode printing areas on the first surface in step S150, the straight line group corresponding to the electrode printing area that needs to be subjected to secondary laser grooving processing in step S150 can be determined respectively by executing step S130, and the embodiment of the present invention does not make specific limitations on this.

[0049] Refer to Figure 3 , a schematic diagram showing the relationship between a first groove and at least two straight lines intersecting the first groove provided by the embodiment of the present invention is shown. As Figure 3 shown, in the target silicon wafer 10, the straight lines intersecting the first groove 11 include the first straight line 21 and the second straight line 22, and the first straight line 21, the second straight line 22 intersect the first groove 11 and there is only one intersection point 01.

[0050] As an optional implementation manner, in step S130, at least two curves intersecting the first groove can also be determined, and the at least two curves intersect the first groove and have a common intersection point. The embodiment of the present invention does not make specific limitations on the shape of the lines that intersect the first groove and have a common intersection point.

[0051] Then, through step S140, a secondary laser grooving pattern corresponding to the target silicon wafer is determined according to the at least two straight lines.

[0052] It is understandable that both the first groove and the second groove obtained in step S150 are grooves with a certain width. To increase the probability that the electrode paste corresponding to the electrode to be printed falls into the groove, the widths of the first groove and the second groove can be made greater than the width of the electrode to be printed.

[0053] Specifically, according to the preset width of the second groove, the secondary laser grooving pattern corresponding to the first groove can be determined with the part of the straight line intersecting the first groove that falls into the target silicon wafer as the center line. Among them, the first groove in step S140 can be any one of the first grooves obtained in step S120. The straight lines intersecting the first groove are at least two straight lines determined by step S130 to intersect with the first groove. In the embodiment of the present invention, according to the preset width of the second groove and the straight line group corresponding to each electrode printing area, the secondary laser grooving pattern corresponding to each electrode printing area can be determined respectively through step S140, and based on the secondary laser grooving pattern corresponding to each electrode printing area, the electrode printing area can be subjected to secondary laser grooving treatment through step S150 to obtain the second groove.

[0054] As Figure 3 shown, the part of the first straight line 21 that falls into the target silicon wafer 10 is 21-1, and the part of the second straight line 22 that falls into the target silicon wafer 10 is 22-1. During the execution of step S150, the first part in the secondary laser grooving pattern can be determined with the part of the first straight line 21 that falls into the target silicon wafer 10, i.e., 21-1, as the center line according to the preset width of the second groove, and the second part in the secondary laser grooving pattern can be determined with the part of the second straight line 22 that falls into the target silicon wafer 10, i.e., 22-1, as the center line according to the preset width of the second groove, and the figure formed by the first part and the second part is determined as the secondary laser grooving pattern.

[0055] Finally, through step S150, the electrode printing area is subjected to secondary laser grooving treatment according to the secondary laser grooving pattern to obtain the second groove, and the second groove only intersects with one first groove.

[0056] In the embodiment of the present invention, the laser grooving process parameters of step S120 and step S150 can adopt the process parameters of existing laser grooving, which are not elaborated in the embodiment of the present invention.

[0057] During the actual production process, even if printing deviation occurs, when the deviation degree is small, since the width of the first groove is greater than the width of the electrode to be printed, the electrode paste corresponding to the electrode to be printed will still fall into the first groove and form an ohmic contact with the first groove; when the deviation degree is large, the part of the electrode paste corresponding to the electrode to be printed that does not fall into the first groove will fall into the second groove and form an ohmic contact with the second groove. Thus, the electrode loss caused by printing deviation can be reduced, thereby improving the ohmic contact between the heavily doped region and the electrode of the target silicon wafer in the case of printing deviation.

[0058] Step S160: Prepare a target solar cell based on the target silicon wafer that has undergone secondary laser grooving treatment.

[0059] In an embodiment of the present invention, the target solar cell is a selective emitter solar cell including the target silicon wafer that has undergone secondary laser grooving treatment.

[0060] In step S160, based on the target silicon wafer that has undergone secondary laser grooving treatment, the target solar cell can be prepared by using the preparation method of the existing selective emitter solar cell, and the embodiments of the present invention do not make specific limitations thereto.

[0061] In the related art, due to problems with the accuracy of the printing camera and the accuracy of the printing machine itself, printing deviation occurs. Only a small part of the printed electrode paste falls into the first groove obtained by laser grooving treatment, resulting in serious electrode loss, poor ohmic contact between the printed electrode and the heavily doped region, and further leading to problems such as low open-circuit voltage and low photoelectric conversion efficiency in the solar cell prepared based on this silicon wafer. In the actual production process, solar cells with the above problems are usually degraded into low-efficiency cell wafers, thereby increasing the cost of cell manufacturing. The solar cell preparation method provided by the embodiments of the present invention, even in the case of printing deviation, the part or all of the electrode paste that does not fall into the first groove will fall into the second groove and form a good ohmic contact with the second groove, reducing the electrode loss caused by printing deviation, improving the ohmic contact between the heavily doped region and the electrode of the target silicon wafer in the case of printing deviation, and improving the photoelectric conversion efficiency of the solar cell prepared based on the target silicon wafer that has undergone secondary laser grooving treatment. In addition, in the case of printing deviation, the solar cell prepared based on the target silicon wafer that has undergone secondary laser grooving treatment does not need to be degraded into a low-efficiency cell wafer, reducing the cost of cell manufacturing.

[0062] Optionally, in one implementation manner, step S150 of performing secondary laser grooving treatment on the electrode printing area according to the secondary laser grooving pattern to obtain the second groove includes:

[0063] S151. According to the secondary laser grooving pattern, perform secondary laser grooving on at least two electrode printing areas in the first surface close to the first edge of the target silicon wafer to obtain a second groove.

[0064] Wherein, the first edge is the edge of the target silicon wafer parallel to the first groove.

[0065] Since printing offset is usually clockwise rotation offset and counterclockwise rotation offset centered on the center point of the target silicon wafer, the offset degree between the first groove close to the center point of the target silicon wafer and the printed electrode is relatively small. As the distance between the first groove and the center point increases, the offset degree between the first groove and the printed electrode gradually increases. Further, in the case of a relatively small offset degree, since the width of the first groove is greater than the width of the electrode to be printed, the electrode paste corresponding to the electrode to be printed will still fall into the first groove and form an ohmic contact with the first groove; while in the case of a relatively large offset degree, there is a risk that the electrode paste corresponding to the electrode to be printed does not fall into the first groove.

[0066] Based on this, in the process of performing secondary laser grooving on the electrode printing area according to the secondary laser grooving pattern, it is possible to only perform secondary laser grooving on the electrode printing area where the first groove with a relatively large offset degree is located, that is, only perform secondary laser grooving on at least two electrode printing areas close to the first edge of the target silicon wafer. For the electrode printing area close to the center point of the target silicon wafer, no secondary laser grooving is required. Thus, while reducing the electrode loss caused by printing offset and improving the ohmic contact between the heavily doped area and the electrode of the target silicon wafer, the range of secondary laser grooving on the first surface is also reduced, and the cost of laser grooving the target silicon wafer is lowered. Exemplarily, it is possible to only perform secondary laser grooving on two electrode printing areas close to the first edge of the target silicon wafer, or only perform secondary laser grooving on four electrode printing areas close to the first edge of the target silicon wafer.

[0067] Wherein, the first edge is the edge of the target silicon wafer parallel to the first groove. Refer to Figure 4 , which shows a schematic diagram of a target silicon wafer after secondary laser grooving provided by an embodiment of the present invention. As Figure 4 shown, the first edge 12 of the target silicon wafer 10 is the edge of the target silicon wafer 10 parallel to the first groove 11.

[0068] As an example, refer to Figure 4 , perform secondary laser grooving on four electrode printing areas in the first surface close to the first edge 12 of the target silicon wafer 10 according to the secondary laser grooving pattern to obtain a second groove 13.

[0069] Optionally, in one embodiment, a first straight line formed by the intersection point and the center point of the target silicon wafer is perpendicular to a second straight line parallel to the first groove.

[0070] Refer to Figure 4 , a straight line formed by the intersection point 01 of the first groove 11 and the second groove 13 and the center point 02 of the target silicon wafer 10 is the first straight line 23; a straight line parallel to the first groove 11 is the second straight line 24; in the embodiment of the present invention, the first straight line 23 and the second straight line 24 are perpendicular.

[0071] In the method for manufacturing a solar cell provided by the embodiment of the present invention, a first straight line formed by the intersection point of the first groove and the second groove and the center point of the target silicon wafer is perpendicular to a second straight line parallel to the first groove. In the case of rotational offset centered on the center point of the target silicon wafer, it can make as much electrode paste that does not fall into the first groove fall into the second groove as possible, reduce the electrode loss caused by printing offset, and improve the ohmic contact between the heavily doped region and the electrode in the target silicon wafer.

[0072] Optionally, in one embodiment, when the secondary laser grooving pattern includes two straight lines, the minimum angle between the second groove and the first groove is 1.5° to 2.5°.

[0073] As Figure 4 shown, when the secondary laser grooving pattern includes two straight lines, the minimum angle θ between the second groove 13 and the first groove 11 can be one of 1.5°, 1.8°, 2.0°, 2.3°, 2.5° or a range value between any two of them.

[0074] Optionally, in one embodiment, when the number of straight lines in the secondary laser grooving pattern is greater than 2, the minimum angle between the second groove and the first groove is 0.5° to 1.5°, for example, it can be one of 0.5°, 0.8°, 1.0°, 1.3°, 1.5° or a range value between any two of them.

[0075] In the method for manufacturing a solar cell provided by the embodiment of the present invention, when the secondary laser grooving pattern includes two straight lines, the minimum angle between the second groove and the first groove is 1.5° to 2.5°; when the number of straight lines in the secondary laser grooving pattern is greater than 2, the minimum angle between the second groove and the first groove is 0.5° to 1.5°. It can avoid the intersection of the second groove and other first grooves outside the first groove in the electrode printing area where the second groove is located, improve the utilization rate of the second groove, and while reducing the electrode loss caused by printing offset, reduce the production cost of the target solar cell.

[0076] Optionally, in one embodiment, before performing laser grooving on the electrode printing area in the first surface of the target silicon wafer in step S120 to obtain the first groove, the method further includes:

[0077] S121. Determine at least one electrode printing area in the first surface of the target silicon wafer according to the printing positions corresponding to the electrodes to be printed.

[0078] Wherein, the printing positions corresponding to the electrodes to be printed are the printing positions of each electrode to be printed in the first surface.

[0079] In the embodiments of the present invention, considering the printing offset problem, the range of the electrode printing area determined according to the printing positions can be larger than the range indicated by the printing positions. Thus, after obtaining the first groove by performing laser grooving on the electrode printing area in step S120, a second groove can be obtained by performing secondary laser grooving on the electrode printing area in step S150.

[0080] It can be understood that the number of electrode printing areas in the first surface can be determined according to the number of electrodes to be printed in the target solar cell. Among them, the number of electrode printing areas is the same as the number of electrodes to be printed, and the electrode printing areas and the electrodes to be printed correspond one by one. Exemplarily, for a Tunnel Oxide Passivated Contact solar cell (TOPCon), the number of electrodes to be printed is 148, and the number of electrode printing areas determined by step S121 is also 148.

[0081] Optionally, in one embodiment, the width of the first groove and / or the second groove is 70 μm to 90 μm. For example, the width of the first groove can be one of 70 μm, 75 μm, 80 μm, 85 μm, 90 μm or any range value between any two of them; the width of the second groove can be one of 70 μm, 75 μm, 80 μm, 85 μm, 90 μm or any range value between any two of them.

[0082] It should be noted that the width of the second groove can be the same as or different from the width of the first groove. The embodiments of the present invention do not specifically limit the size relationship between the width of the first groove and the width of the second groove.

[0083] Optionally, in one embodiment, the width of the electrode to be printed is 35 μm to 45 μm. Exemplarily, the width of the electrode to be printed can be one of 35 μm, 37 μm, 39 μm, 41 μm, 43 μm and 45 μm or any range value between any two of them.

[0084] An embodiment of the present invention also provides a solar cell, which is prepared by using the preparation method of the solar cell described in any one of the above.

[0085] An embodiment of the present invention also provides an electrical device, which includes the solar cell described above, and the solar cell serves as the power supply of the electrical device.

[0086] The present invention will be described in detail below through embodiments.

[0087] Embodiment 1

[0088] (1) Take an N-type silicon wafer with dimensions of 182 mm × 183.75 mm, and simultaneously perform trough texturing on the first surface and the second surface of the N-type silicon wafer by using a texturing solution; the texturing solution includes sodium hydroxide with a volume ratio of 1.9%, a texturing additive with a volume ratio of 0.58%, and deionized water; the conditions for texturing are: the texturing temperature is 82 °C, and the texturing duration is 420 s.

[0089] (2) Perform boron diffusion treatment on the first surface of the textured N-type silicon wafer, and determine the N-type silicon wafer after boron diffusion treatment as the target silicon wafer; among them, the conditions for boron diffusion treatment are: the temperature is 900 °C, the diffusion duration of boron diffusion treatment is 740 s, and the gas flow rate of the boron source is 600 sccm.

[0090] (3) Perform laser grooving treatment on the electrode printing area in the first surface of the target silicon wafer to obtain a first groove; among them, the groove depth of the laser grooving treatment is 1.4 μm, and the groove width of the laser grooving treatment is 70 μm.

[0091] (4) Determine a first straight line and a second straight line that intersect the first groove and have a common intersection point, and the first straight line and the second straight line intersect the first groove and have a common intersection point.

[0092] (5) Determine the secondary laser grooving pattern corresponding to the target silicon wafer according to the first straight line and the second straight line.

[0093] (6) According to the secondary laser grooving pattern, perform secondary laser grooving treatment on the four electrode printing areas in the first surface close to the first edge of the target silicon wafer to obtain a second groove; among them, the groove depth of the secondary laser grooving treatment is 1.4 μm, and the groove width of the secondary laser grooving treatment is 70 μm; the second groove only intersects with one first groove, and the first straight line formed by the intersection point of the second groove and the first groove and the center point of the target silicon wafer is perpendicular to the second straight line parallel to the first groove; the minimum included angle between the second groove and the first groove is 1.5°.

[0094] (7) Take the target silicon wafer that has undergone secondary laser grooving treatment and perform secondary boron diffusion treatment to form a boron-silicate glass layer (BSG) of about 100 nm on the first surface and the second surface of the target silicon wafer.

[0095] (8) Use the first alkaline polishing solution to polish the second surface of the target silicon wafer that has undergone secondary boron diffusion treatment to remove the BSG layer; the first alkaline polishing solution includes potassium sodium hydroxide, alkaline polishing additive, and deionized water. Among them, the proportion of potassium sodium hydroxide in the first alkaline polishing solution is 5.6%, the proportion of the alkaline polishing additive in the first alkaline polishing solution is 1.2%, and deionized water; the polishing conditions are: the polishing temperature is 70 °C, and the polishing duration is 420 s; the square size of the morphology of the polished second surface tested under a microscope is 6 μm to 8 μm.

[0096] (9) Stack a polysilicon oxide layer and a doped amorphous silicon layer on the polished second surface in sequence.

[0097] (10) Perform phosphorus diffusion treatment on the doped amorphous silicon layer to obtain a phosphorus-doped amorphous silicon layer; the sheet resistance of the phosphorus-doped amorphous silicon layer is 50 Ω / sq, and the surface concentration is about 7×10 20 cm -3 ; the conditions for phosphorus diffusion treatment are: the temperature of phosphorus diffusion treatment is 850 °C, and the duration of phosphorus diffusion treatment is 7 min.

[0098] (11) Take the target silicon wafer that has undergone phosphorus diffusion treatment and perform BOE (Buffered Oxide Etch) cleaning to obtain the cleaned target silicon wafer. The cleaned target silicon wafer includes the cleaned phosphorus-doped amorphous silicon layer and the cleaned first surface; the BOE cleaning solution includes potassium hydroxide, cleaning additive, and deionized water. Among them, the proportion of potassium sodium hydroxide in the cleaning solution is 4.1%, the proportion of the alkaline polishing additive in the cleaning solution is 0.45%, and deionized water; the BOE cleaning conditions are: the cleaning temperature is 80 °C, and the cleaning duration is 280 s.

[0099] (12) Perform atomic layer deposition (ALD) coating treatment on the cleaned first surface to obtain the target silicon wafer after coating treatment. The target silicon wafer after coating treatment includes an aluminum oxide thin film covering the cleaned first surface; among them, the thickness of the aluminum oxide thin film is 2 nm to 3 nm, and the aluminum oxide thin film can provide surface field passivation of negative charges, increasing the photoelectric conversion efficiency of the solar cell by about 0.3%.

[0100] (13) Perform silicon nitride coating on the target silicon wafer after coating treatment to obtain the target silicon wafer after silicon nitride coating. The target silicon wafer after silicon nitride coating includes a first silicon nitride film covering the surface of the alumina film and a second silicon nitride film covering the surface of the cleaned phosphorus-doped amorphous silicon layer. Among them, the thickness of the first silicon nitride film is 70 nm, the refractive index is 2.09, the thickness of the second silicon nitride film is 80 nm, and the refractive index is 2.12.

[0101] (14) Take the target silicon wafer after silicon nitride coating and perform screen printing to print silver electrodes on the first surface and the second surface. The width of the printed electrode is 35 μm.

[0102] (15) Sinter the target silicon wafer after printing the electrodes to obtain the target solar cell. Among them, the peak temperature of sintering is 820 °C.

[0103] Example 2

[0104] The difference between Example 2 and Example 1 is that in step (6), the minimum angle between the second groove and the first groove is 2.0°.

[0105] Example 3

[0106] The difference between Example 3 and Example 1 is that in step (6), the minimum angle between the second groove and the first groove is 2.5°.

[0107] Example 4

[0108] The difference between Example 4 and Example 1 is that in step (3), the groove width of the laser grooving treatment is 80 μm.

[0109] Example 5

[0110] The difference between Example 5 and Example 1 is that in step (3), the groove width of the laser grooving treatment is 90 μm.

[0111] Example 6

[0112] The difference between Example 6 and Example 1 is that in step (6), the groove width of the secondary laser grooving treatment is 80 μm.

[0113] Example 7

[0114] The difference between Example 7 and Example 1 is that in step (6), the groove width of the secondary laser grooving treatment is 90 μm.

[0115] Example 8

[0116] Example 8 is different from Example 1 in that in step (6), all electrode printing areas in the first surface are subjected to secondary laser grooving according to the secondary laser grooving pattern to obtain a second groove.

[0117] Example 9

[0118] Example 9 is different from Example 1 in that in step (14), the width of the printed electrode is 40 μm.

[0119] Example 10

[0120] Example 10 is different from Example 1 in that in step (14), the width of the printed electrode is 45 μm.

[0121] Example 11

[0122] Example 11 is different from Example 1 in that:

[0123] In step (4), a first straight line, a second straight line, a third straight line, and a fourth straight line that intersect the first groove and have a common intersection point are determined, and the first straight line, the second straight line, the third straight line, and the fourth straight line intersect the first groove and have a common intersection point;

[0124] In step (6), the minimum angle between the second groove and the first groove is 0.5°.

[0125] Example 12

[0126] Example 12 is different from Example 11 in that in step (6), the minimum angle between the second groove and the first groove is 1.5°.

[0127] Example 13

[0128] Example 13 is different from Example 11 in that in step (6), the minimum angle between the second groove and the first groove is 1.0°.

[0129] Comparative Example 1

[0130] Comparative Example 1 is different from Example 1 in that steps (4) to (6) are not included; in step (7), the target silicon wafer that has undergone the laser grooving treatment in step (3) is subjected to secondary boron diffusion treatment to form a boron-silicate glass layer of about 100 nm on the first surface and the second surface of the target silicon wafer.

[0131] In summary, in the case of printing deviation, the solar cells obtained after sintering in Examples 1 to 13 were tested, and their electrical data were: open circuit voltage of 694 mV and photoelectric conversion efficiency of 23.60%; the solar cell obtained after sintering in Comparative Example 1 was tested, and its electrical data were: open circuit voltage of 695 mV and photoelectric conversion efficiency of 23.62%. For the method for preparing a solar cell provided in the embodiments of the present invention, in the case where the printed electrode paste cannot completely fall into the first groove due to the accuracy of the printing camera and the printing machine platform, some or all of the electrode paste that does not fall into the first groove will fall into the second groove, forming an ohmic contact with the second groove, reducing the electrode loss caused by printing deviation, and improving the ohmic contact between the heavily doped region of the target silicon wafer and the electrode in the case of printing deviation, which can increase the open circuit voltage of the target solar cell prepared based on the target silicon wafer processed by secondary laser grooving by 1 mV and increase the photoelectric conversion efficiency by 0.02%.

[0132] It should be noted that in this article, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "including a..." does not exclude the presence of additional identical elements in the process, method, article or device including that element.

[0133] Through the description of the above embodiments, those skilled in the art can clearly understand that the above embodiment methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. The computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions for causing a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0134] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention. All of these are within the protection scope of the present invention.

Claims

1. A method for preparing a solar cell, characterized in that The method includes: Obtaining a target silicon wafer, where the target silicon wafer is a silicon wafer after a first boron diffusion treatment; Performing laser grooving on the electrode printing areas in the first surface of the target silicon wafer to obtain first grooves; the first surface is the surface of the target silicon wafer after the first boron diffusion treatment; the electrode printing areas correspond one-to-one to the electrodes to be printed; Determining at least two lines that intersect the first grooves; the at least two lines intersect the first grooves and have a common intersection point; Determining a secondary laser grooving pattern corresponding to the target silicon wafer according to the at least two lines; Performing secondary laser grooving on the electrode printing areas according to the secondary laser grooving pattern to obtain second grooves; each second groove intersects only one of the first grooves; Preparing a target solar cell based on the target silicon wafer after the secondary laser grooving treatment.

2. The method according to claim 1, characterized in that, The step of performing secondary laser grooving on the electrode printing areas according to the secondary laser grooving pattern to obtain second grooves includes: Performing secondary laser grooving on at least two electrode printing areas in the first surface of the target silicon wafer that are close to the first edge of the target silicon wafer according to the secondary laser grooving pattern to obtain second grooves; Wherein, the first edge is the edge of the target silicon wafer parallel to the first grooves.

3. The method according to claim 1, characterized in that, A first line formed by the intersection point and the center point of the target silicon wafer is perpendicular to a second line parallel to the first grooves.

4. The method according to claim 1, wherein When the secondary laser grooving pattern includes two lines, the minimum included angle between the second grooves and the first grooves is 1.5° to 2.5°.

5. The method according to claim 1, wherein When the number of lines in the secondary laser grooving pattern is greater than 2, the minimum included angle between the second grooves and the first grooves is 0.5° to 1.5°.

6. The method according to claim 1, wherein Before performing laser grooving on the electrode printing areas in the first surface of the target silicon wafer to obtain first grooves, the method further includes: Determining at least one electrode printing area in the first surface of the target silicon wafer according to the printing positions corresponding to the electrodes to be printed.

7. The method according to claim 1, wherein The width of the first grooves and / or the second grooves is 70 μm to 90 μm.

8. The method according to claim 1, wherein The width of the electrodes to be printed is 35 μm to 45 μm.

9. A solar cell, characterized in that, The solar cell is prepared by using the method for preparing a solar cell according to any one of claims 1 to 8.

10. An electrical device, characterized in that, The electrical device includes the solar cell according to claim 9, and the solar cell serves as the power supply of the electrical device.

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