A solar cell and its preparation method and laser annealing device

Abstract

The present application relates to the field of photovoltaic technology, and to a solar cell and a method for preparing the same, as well as a laser annealing device. The preparation method comprises: performing a first local heating on a silicon wafer after back electrode printing; performing back field printing, and performing a second local heating; performing positive electrode printing, and performing a third local heating; the first local heating, the second local heating, and the third local heating are all performed by heating only by laser irradiation of the grid lines. The first local heating, the second local heating, and the third local heating are performed by heating only by laser irradiation of the grid lines, rather than heating the entire silicon wafer, which can not only form a good ohmic contact, but also will not damage the amorphous silicon film layer. Since good ohmic contact can be achieved at high temperature, the use of the present application solution can reduce the silver paste content and reduce the production cost of solar cells. Moreover, for silver-copper paste and electroplating copper technology, the contact resistance can be reduced and the battery efficiency can be improved.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to a solar cell and a preparation method thereof, and a laser annealing device. Background Art

[0002] As an efficient technology route that has attracted great attention from the industry in recent years, solar cell technology has become the industry-recognized next-generation commercial photovoltaic industry technology due to its high photoelectric conversion efficiency, excellent performance, large cost reduction space, and good prospects for grid parity.

[0003] However, there are still technical difficulties in solar cell technology.

[0004] For high-efficiency heterojunction cells, one of the current technical difficulties is the high cost of low-temperature silver paste. In order to ensure the passivation effect of the hydrogenated amorphous silicon layer of the heterojunction cell, the temperature is generally below 200°C throughout the entire production process. In order to maintain good contact between the gate line and the TCO film layer, the printing process can only use low-temperature silver paste, and the drying and curing temperature is generally maintained at around 200°C.

[0005] The existing heating method for drying and curing is to heat the entire furnace body through a resistance wire, and heat the entire battery cell by heat conduction, so as to form an ohmic contact between the slurry and the TCO layer, thereby reducing the contact resistance.

[0006] Reference Figure 1 At present, a tower drying furnace is used for drying. The drying reaction is carried out in a closed space. There is a heating resistor wire 2 inside the drying furnace to provide the drying temperature required for the silver paste. After the silicon wafer 1 is printed with slurry (back electrode, back field, positive electrode), silver paste exists on the surface and needs to be dried and shaped in time. The temperature inside the tower drying furnace is maintained at 200°C. The silicon wafer is supported by a pallet, and the pallet is raised and lowered by a hinge 3. The entire drying process requires the silicon wafer 1 to maintain a high temperature of 200°C for about 10 minutes in the drying furnace cavity 4. The heat of the resistor wire is transferred to the silicon wafer by heat conduction of the air in the furnace. After the silicon wafer is heated as a whole, the slurry will also heat up, forming a basic gate line shaping process.

[0007] After basic shaping, the silicon wafer needs to be transported to the curing furnace for curing. Figure 2 The curing furnace still uses the resistance wire 2 to heat the silicon wafer 1 as a whole.

[0008] This method requires heating the entire silicon wafer. The amorphous silicon layer limits the upper temperature of the thermal process to no more than 200°C, resulting in a long drying and curing time. Tower drying must be used first, and then the wafer must be cured in a curing furnace. This also makes the equipment structure more complicated to a certain extent, increasing the risk of downtime of mass production equipment. Summary of the invention

[0009] The purpose of the embodiments of the present application is to provide a solar cell and a method for preparing the same, as well as a laser annealing device.

[0010] In a first aspect, the present application provides a method for preparing a solar cell, comprising:

[0011] Perform the first local heating on the silicon wafer after back electrode printing;

[0012] Perform back field printing and perform a second local heating;

[0013] Printing the positive electrode and performing a third local heating;

[0014] The first local heating, the second local heating and the third local heating all use laser to irradiate only the grid lines for heating.

[0015] By setting the first local heating, the second local heating and the third local heating to heat only the gate lines with laser irradiation, it is possible to achieve concentrated heating of the gate lines, that is, only the local area of ​​the gate lines is subjected to high-temperature annealing treatment, rather than heating the entire silicon wafer. The present application method only heats the gate lines to obtain good ohmic contact. The present application method does not require drying in a tower drying furnace and curing in a curing furnace twice. Drying and curing can be carried out simultaneously, which takes less time and makes the equipment structure simpler, reducing the risk of downtime of mass production equipment.

[0016] The method of the present application is particularly suitable for heterojunction cells, which can not only form a good ohmic contact, but also is expected to reduce the amount of silver paste used and reduce the manufacturing cost of solar cells.

[0017] For heterojunction cells, the current conventional method of drying and curing the entire silicon wafer is that the amorphous silicon film layer in the amorphous silicon film layer cell limits the upper limit of the heating temperature, which cannot exceed 200°C, so the effect of the ohmic contact formed is not very good. If the temperature continues to be increased, the contact resistance between the gate line and the TCO will be smaller, but the high temperature will damage the amorphous silicon film layer, resulting in a decrease in battery efficiency. The present application creatively proposes that the first local heating, the second local heating, and the third local heating are all heated by laser irradiation of only the gate line, which can increase the heating temperature and break through this limitation. It can not only form a good ohmic contact, but also will not damage the amorphous silicon film layer. Increasing the heating temperature can greatly reduce the contact resistance between the gate line and the TCO and improve the battery efficiency. Furthermore, since good ohmic contact can be achieved at high temperature, the amount of low-temperature silver paste used can be reduced. Therefore, the use of the present application solution can reduce the silver paste content and reduce the production cost of solar cells.

[0018] In other optional embodiments of the present application, the laser is used to irradiate only the grid lines for heating by relatively moving the laser along the length direction of the grid lines for irradiation.

[0019] In other optional embodiments of the present application, when laser is used to irradiate only the grid lines for heating, the laser irradiation width is greater than or equal to the grid line width.

[0020] In other optional embodiments of the present application, the laser irradiation width is greater than the gate line width and is no greater than 10 microns.

[0021] In other optional embodiments of the present application, the temperatures of the first local heating, the second local heating, and the third local heating are all between 250°C and 300°C.

[0022] In a second aspect, the present application provides a solar cell, which is manufactured using any of the aforementioned methods for manufacturing a solar cell.

[0023] In a third aspect, the present application provides a laser annealing device, which is applied to any of the aforementioned methods for preparing a solar cell;

[0024] The laser annealing device includes a cavity, a laser and a positioning device;

[0025] A transmission roller is provided in the cavity for transmitting the silicon wafer;

[0026] The positioning device is used to fix the silicon wafer, locate the gate line position on the silicon wafer, and transmit the gate line position data;

[0027] The laser is placed above the transmission roller and is used to perform the first local heating, the second local heating or the third local heating on the passing silicon wafer according to the gate line position data.

[0028] In other optional embodiments of the present application, the positioning device includes a detection component;

[0029] The detection component is a camera;

[0030] The camera determines the position of the grid line by acquiring the two long sides of the grid line; or

[0031] The gate line position marks are set on the surface of the silicon wafer, and the camera determines the position of the gate line by acquiring the marks.

[0032] In other optional embodiments of the present application, the positioning device includes a clamping assembly;

[0033] The clamping assembly includes a roller, a connecting rod, a first sliding rod and a second sliding rod;

[0034] The roller is connected to the first slide bar or the second slide bar through a connecting rod; the roller is used to contact the side edge of the silicon wafer;

[0035] The first slide bar and the second slide bar are arranged opposite to each other; the first slide bar and the second slide bar are used to be arranged on opposite sides of the silicon wafer, and the first slide bar and the second slide bar can move closer to each other or away from each other so that the roller contacts the fixed silicon wafer.

[0036] In other optional embodiments of the present application, the laser annealing device is provided with an exhaust system, and the exhaust system is arranged at the top of the cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 It is a schematic diagram of an existing drying tower furnace;

[0039] Figure 2 It is a schematic diagram of an existing curing furnace;

[0040] Figure 3 A schematic diagram of the laser irradiation area of ​​the laser annealing device provided in an embodiment of the present application;

[0041] Figure 4 A schematic diagram of the structure of a laser annealing device provided in an embodiment of the present application;

[0042] Figure 5 A schematic diagram of camera detection of a laser annealing device provided in an embodiment of the present application;

[0043] Figure 6 A schematic diagram of a clamping assembly of a laser annealing device provided in an embodiment of the present application.

[0044] Icons: 1-silicon wafer; 2-resistance wire; 3-hinge; 4-cavity; 10-silicon wafer; 11-gate line; 12-laser irradiation area; 100-laser annealing device; 110-cavity; 111-transmission device; 112-top; 120-laser; 131-camera; 132-clamping assembly; 1321-roller; 1322-connecting rod; 1323-first slide bar; 1324-second slide bar; 140-exhaust system. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0047] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0048] In the description of the embodiments of the present application, it should be understood that the terms "up", "left", "right", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of the application are conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0049] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0050] In the description of the embodiments of the present application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a connection between the two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0051] Please refer to Figure 3 to Figure 6 Some embodiments of the present application provide a method for preparing a solar cell, comprising:

[0052] Perform the first local heating on the silicon wafer after back electrode printing;

[0053] Perform back field printing and perform a second local heating;

[0054] Printing the positive electrode and performing a third local heating;

[0055] The first local heating, the second local heating and the third local heating all use laser to irradiate only the grid lines for heating.

[0056] By setting the first local heating, the second local heating and the third local heating to heat only the gate line with laser, it is possible to achieve concentrated heating of the gate line, that is, only the local area of ​​the gate line is subjected to high temperature annealing treatment without heating the entire silicon wafer. In addition, drying and curing can be performed simultaneously, greatly improving production efficiency.

[0057] For heterojunction cells, a more important advantage of the method of the present application is that it can reduce the slurry cost.

[0058] Paste accounts for a large part of the cost in solar cell manufacturing. In traditional PERC cells, the paste cost accounts for more than 30% of the non-silicon cost. Heterojunction cells consume more low-temperature silver paste, and the cost of low-temperature silver paste accounts for more than 50% of the non-silicon cost of heterojunction cells, which seriously limits the large-scale expansion of heterojunction cells. This is because heterojunction cells need to maintain a low contact resistance, which requires a higher Ag content in the silver paste (relative to the higher Ag content in the paste used in conventional PERC).

[0059] However, the amorphous silicon film layer of the heterojunction battery limits the upper temperature limit of solidification. The conventional method of heating the entire silicon wafer cannot exceed 200°C (there may be slight fluctuations), so the effect of the formed ohmic contact is not very good. If the temperature continues to increase, the contact resistance between the gate line and the TCO will be smaller, but the high temperature will damage the amorphous silicon film layer, resulting in a decrease in battery efficiency. The present application creatively proposes that the first local heating, the second local heating, and the third local heating are all performed by laser irradiation of only the gate line for heating, which breaks through this limitation. It can not only form a good ohmic contact, but also will not damage the amorphous silicon film layer.

[0060] Furthermore, in some embodiments of the present application, the temperatures of the first local heating, the second local heating, and the third local heating are all between 250°C and 300°C.

[0061] The inventors found that by setting the temperature of the first local heating, the second local heating, and the third local heating to 250°C to 300°C, the contact resistance between the gate line and the TCO can be greatly reduced, and the efficiency is the highest, the amorphous silicon film layer will not be damaged, and the defects in the amorphous silicon film can be repaired to a certain extent. Since the method of the present application can locally heat the gate line at a higher temperature to achieve low contact resistance, it is expected to reduce the Ag content in the slurry and reduce the slurry cost.

[0062] Further optionally, the temperatures of the first local heating, the second local heating, and the third local heating are all between 255°C and 295°C. Further optionally, the temperatures of the first local heating, the second local heating, and the third local heating are all between 260°C and 290°C. Further optionally, the temperatures of the first local heating, the second local heating, and the third local heating are all between 265°C and 285°C. Further optionally, the temperatures of the first local heating, the second local heating, and the third local heating are all between 270°C and 280°C.

[0063] Further, in some embodiments of the present application, the temperatures of the first local heating, the second local heating, and the third local heating may be the same or different. For example, the temperatures of the first local heating, the second local heating, and the third local heating are all 258°C, 268°C, 275°C, or 278°C. Or the temperatures of the first local heating, the second local heating, and the third local heating are 256°C, 266°C, or 276°C, respectively.

[0064] Furthermore, the present application solution only requires the addition of a laser annealing device without the need to add any other additional process steps, and thus has good compatibility with current production lines and a wider range of applications.

[0065] Furthermore, in the present application, the laser annealing device only needs one wavelength, and does not involve the treatment of the TCO layer or the amorphous silicon layer, and hardly affects the TCO layer and the amorphous silicon. Furthermore, in the present application, only the gate line is annealed, and the specific wavelength parameters can be determined according to different slurries and front-end processes.

[0066] It should also be noted that the method for preparing a solar cell provided in the present application can be applied not only to the production of HIT cells, but also to the printing lines of PERC cells and TOPCON cells, and can achieve almost the same effect.

[0067] In addition to applying different types of battery printing lines, this application solution can also be used to reduce costs. For HIT batteries, this solution can be used to reduce the Ag content in the slurry. Even for Cu electroplating technology, this solution can also achieve the effect of reducing contact resistance and improving battery efficiency. And for the currently popular silver-copper slurry and laser transfer, this solution can also be applied. The difference is that the setting of laser parameters and accuracy requirements can be adjusted according to actual conditions.

[0068] Furthermore, in some embodiments of the present application, the method for preparing the solar cell comprises the following steps:

[0069] Step S1, performing the first local heating on the silicon wafer after the back electrode is printed.

[0070] The silicon wafer after the back electrode printing can be obtained by using the current conventional process. It is obtained by printing the back electrode on the silicon wafer.

[0071] Furthermore, the first local heating of the silicon wafer after the back electrode printing is performed by using laser to irradiate only the gate line for heating.

[0072] Furthermore, the use of laser to irradiate only the grid lines for heating is to relatively move the laser along the length direction of the grid lines for irradiation.

[0073] Furthermore, when laser is used to irradiate only the grid lines for heating, the laser irradiation width is greater than or equal to the grid line width.

[0074] Furthermore, in some embodiments of the present application, the laser irradiation width is greater than the gate line width and is no greater than 10 microns.

[0075] For example, refer to Figure 3 ,exist Figure 3 In the illustrated embodiment, a plurality of gate lines 11 are sequentially arranged on a silicon wafer 10, and the dotted frame in the figure exemplarily shows a laser irradiation area 12. It can be seen that the laser irradiation direction is consistent with the length direction of the gate line 11. The laser irradiation width is slightly wider than the gate line width. In this case, the laser can completely irradiate the gate line, heat, solidify and anneal the gate line. Through the inventor's long-term research, the laser irradiation width is set to be greater than the gate line width, and not more than 10 microns, which can not only effectively ensure that the temperature of the laser-heated gate line is increased to 250°C to 300°C. Centralized heating of the gate line can achieve high-temperature annealing of a local area of ​​the gate line. Within a certain range, high temperature is conducive to forming a good ohmic contact between the gate line and the TCO, reducing the contact resistance and improving the battery efficiency. And it will not cause damage to the TCO layer on the silicon wafer.

[0076] Exemplarily, the laser irradiation width is greater than the grid line width: 1 micron, 2 microns, 3 microns, 4 microns, 5 microns, 6 microns, 7 microns, 8 microns, 9 microns or 10 microns.

[0077] Furthermore, the laser annealing device 100 is used to perform the first local heating by irradiating only the gate lines with laser.

[0078] Further, refer to Figure 5 The laser annealing device 100 includes a cavity 110, a laser 120 and a positioning device.

[0079] Furthermore, a transmission device 111 is provided in the cavity 110 for transmitting the silicon wafer 10 .

[0080] Optionally, in some embodiments of the present application, the above-mentioned transmission device 111 is a crawler, which can stably and quickly transmit the silicon wafer to the position to be heated, providing favorable guarantee for the subsequent laser to locally heat the gate lines on the silicon wafer.

[0081] Furthermore, the positioning device is used to fix the silicon wafer 10, locate the gate line position on the silicon wafer 10, and transmit the gate line position data.

[0082] Furthermore, the laser 120 is placed above the transmission device 111 and is used to perform a first local heating on the passing silicon wafer 10 according to the gate line position data.

[0083] Furthermore, the positioning device includes a detection component.

[0084] In some embodiments of the present application, reference Figure 5 , the above-mentioned detection component is a camera 131.

[0085] In some embodiments of the present application, the camera 131 determines the position of the grid line by acquiring the two long sides of the grid line.

[0086] The camera 131 takes a picture of the silicon wafer to obtain the positions of the two long sides of the gate line on the silicon wafer, thereby realizing the positioning of the gate line.

[0087] In some embodiments of the present application, a gate line position mark is set on the surface of the silicon wafer 10, and the camera 131 determines the position of the gate line by acquiring the mark.

[0088] The camera 131 takes a picture of the silicon wafer to obtain the position of the mark on the silicon wafer, thereby realizing the positioning of the gate line.

[0089] Furthermore, the positioning device includes a clamping assembly 132 .

[0090] Further, refer to Figure 6 In some embodiments of the present application, the clamping assembly 132 includes a roller 1321 , a connecting rod 1322 , a first sliding rod 1323 and a second sliding rod 1324 .

[0091] Furthermore, the roller 1321 is connected to the first sliding bar 1323 or the second sliding bar 1324 through a connecting rod 1322 ; the roller 1321 is used to contact the side edge of the silicon wafer 10 .

[0092] Furthermore, the first slide bar 1323 and the second slide bar 1324 are arranged opposite to each other; the first slide bar 1323 and the second slide bar 1324 are used to be arranged on opposite sides of the silicon wafer 10, and the first slide bar 1323 and the second slide bar 1324 can move closer to each other or away from each other so that the roller 1321 contacts and fixes the silicon wafer 10.

[0093] Furthermore, the roller 1321 can rotate freely, so as to facilitate contacting and fixing the silicon wafer.

[0094] The clamping assembly 132 clamps and fixes the silicon wafer, and the camera takes a picture. After confirming the position of the gate line on the silicon wafer, the data is sent to the laser, and the laser locally heats the gate line.

[0095] Furthermore, the laser annealing device 100 is provided with an exhaust system 140 , and the exhaust system 140 is disposed at the top 112 of the cavity 110 .

[0096] By providing the exhaust system 140 , harmful gases inside the cavity 110 can be discharged in time, thereby ensuring the working environment inside the cavity 110 .

[0097] In the laser annealing device 100 of the present application, there is no resistance wire in the cavity 110, so heating of the resistance wire is avoided and damage to the TCO layer is avoided.

[0098] For example, refer to Figures 4 to 6 When the laser annealing device 100 of the present application is used for local laser heating, the silicon wafer 10 passes through the laser 120 in the cavity 110 at a certain speed through the crawler drive. The laser 120 can heat the local area of ​​the gate line, and an exhaust system 140 is provided on the top to remove harmful gases. Since the laser 120 only heats the gate line on the surface of the silicon wafer 10 and does not heat the silicon wafer 10 as a whole, the temperature can be set to more than 200°C and will not damage the amorphous silicon layer. The temperature is set at 250°C to 300°C, which can greatly improve the contact resistance between the gate line and the TCO and achieve the best battery efficiency.

[0099] Step S2, performing back field printing and performing a second local heating.

[0100] The back-field printing can be performed by conventional methods in the art, which will not be described in detail here.

[0101] Furthermore, the second local heating also uses laser to irradiate only the grid lines for heating; the temperature of the second local heating is 250°C to 300°C.

[0102] Further optionally, the temperature of the second local heating is between 255°C and 295°C. Further optionally, the temperature of the second local heating is between 260°C and 290°C. Further optionally, the temperature of the second local heating is between 265°C and 285°C. Further optionally, the temperature of the second local heating is between 270°C and 280°C. Exemplarily, the temperature of the second local heating is 258°C, 268°C, 275°C or 278°C.

[0103] Furthermore, the second local heating is also performed by relatively moving the laser along the length direction of the grid line for irradiation.

[0104] Furthermore, the second local heating is also to irradiate the laser along the length direction of the grid line, and the laser irradiation width is greater than or equal to the grid line width.

[0105] Furthermore, in some embodiments of the present application, the laser irradiation width is greater than the gate line width and is no greater than 10 microns.

[0106] Exemplarily, the laser irradiation width is greater than the grid line width: 1 micron, 2 microns, 3 microns, 4 microns, 5 microns, 6 microns, 7 microns, 8 microns, 9 microns or 10 microns.

[0107] The effect of the second local heating can be referred to Figure 3 The laser irradiation direction is consistent with the length direction of the grid line 11. The laser irradiation width is slightly wider than the grid line width.

[0108] Furthermore, the second local heating may be performed by the laser annealing device 100 in step S1.

[0109] Step S3, printing the positive electrode and performing a third local heating;

[0110] The positive electrode printing can be performed by conventional methods in the art, which will not be described in detail here.

[0111] Furthermore, the third local heating also uses laser to irradiate only the grid lines for heating; the temperature of the third local heating is between 250°C and 300°C.

[0112] Further optionally, the temperature of the third local heating is between 255°C and 295°C. Further optionally, the temperature of the third local heating is between 260°C and 290°C. Further optionally, the temperature of the third local heating is between 265°C and 285°C. Further optionally, the temperature of the third local heating is between 270°C and 280°C. Exemplarily, the temperature of the second local heating is 258°C, 268°C, 275°C or 278°C.

[0113] Furthermore, the third local heating is also performed by relatively moving the laser along the length direction of the grid line for irradiation.

[0114] Furthermore, the third local heating is also performed by relatively moving the laser along the length direction of the grid line for irradiation, and the laser irradiation width is greater than or equal to the grid line width.

[0115] Furthermore, in some embodiments of the present application, the laser irradiation width is greater than the gate line width and is no greater than 10 microns.

[0116] Exemplarily, the laser irradiation width is greater than the grid line width: 1 micron, 2 microns, 3 microns, 4 microns, 5 microns, 6 microns, 7 microns, 8 microns, 9 microns or 10 microns.

[0117] The effect of the third local heating can be referred to Figure 3 The laser irradiation direction is consistent with the length direction of the grid line 11. The laser irradiation width is slightly wider than the grid line width.

[0118] Furthermore, the third local heating may be performed by the laser annealing device 100 in step S1.

[0119] It should be noted that other preparation processes are the same as conventional processes for manufacturing solar cells and will not be described in detail here.

[0120] Some embodiments of the present application provide a solar cell, which is manufactured using the method for manufacturing a solar cell of any of the aforementioned embodiments.

[0121] Some embodiments of the present application provide a laser annealing device, which is applied to the method for preparing a solar cell of any of the aforementioned embodiments.

[0122] The laser annealing apparatus is the same as the laser annealing apparatus 100 in step S1.

[0123] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a solar cell, characterized in that: The solar cell comprises: an amorphous silicon film layer; The preparation method comprises: Perform the first local heating on the silicon wafer after back electrode printing; Perform back field printing and perform a second local heating; Printing the positive electrode and performing a third local heating; The first local heating, the second local heating and the third local heating all use laser to irradiate only the grid lines for heating, and the laser irradiation width is larger than the grid line width and not larger than 10 microns; the temperatures of the first local heating, the second local heating and the third local heating are all between 250°C and 300°C.

2. The method for preparing a solar cell according to claim 1, characterized in that: The method of using laser to irradiate only the grid lines for heating is to relatively move the laser along the length direction of the grid lines for irradiation.

3. A solar cell, characterized in that: The solar cell is prepared by the method for preparing the solar cell according to claim 1 or 2.

4. A laser annealing device, characterized in that: A method for preparing a solar cell as claimed in any one of claims 1 to 3; The laser annealing device comprises a cavity, a laser and a positioning device; The cavity is provided with a transmission roller for transmitting the silicon wafer; The positioning device is used to fix the silicon wafer, locate the gate line position on the silicon wafer, and transmit the gate line position data; The laser is placed above the transmission roller, and is used to perform the first local heating, the second local heating, or the third local heating on the silicon wafer passing through according to the gate line position data.

5. The laser annealing device according to claim 4, characterized in that: The positioning device includes a detection component; The detection component is a camera; The camera determines the position of the grid line by acquiring two long sides of the grid line; or A gate line position mark is set on the surface of the silicon wafer, and the camera determines the position of the gate line by acquiring the mark.

6. The laser annealing device according to claim 5, characterized in that: The positioning device includes a clamping assembly; The clamping assembly includes a roller, a connecting rod, a first sliding rod and a second sliding rod; The roller is connected to the first slide bar or the second slide bar through the connecting rod; the roller is used to contact the side edge of the silicon wafer; The first slide bar and the second slide bar are arranged opposite to each other; the first slide bar and the second slide bar are used to be arranged on two opposite sides of the silicon wafer, and the first slide bar and the second slide bar can be moved closer to each other or away from each other so that the roller contacts and fixes the silicon wafer.

7. The laser annealing device according to claim 4, characterized in that: The laser annealing device is provided with an exhaust system, and the exhaust system is arranged on the top of the cavity.

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