CN114927599A - Solar cell, preparation method thereof and laser annealing device - Google Patents

Abstract

The application relates to the technical field of photovoltaics, and relates to a solar cell, a preparation method thereof and a laser annealing device. The preparation method comprises the following steps: carrying out first local heating on the silicon wafer after back electrode printing; performing back field printing and performing second local heating; printing a positive electrode, and carrying out third local heating; the first local heating, the second local heating and the third local heating are all performed by only irradiating the grid line with laser. The first time local heating, the second time local heating and the third time local heating adopt laser to only irradiate the grid line for heating, but not heat the whole silicon wafer, so that good ohmic contact can be formed, and the amorphous silicon film layer can not be damaged. Because can realize good ohmic contact at high temperature, therefore adopt this application scheme can reduce silver thick liquid content, reduce solar cell manufacturing cost. And for silver-copper slurry and copper electroplating technologies, the effects of reducing contact resistance and improving battery efficiency can be achieved.

Description

A kind of solar cell and its preparation method and laser annealing device

technical field

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

Background technique

As a high-efficiency technology route that has attracted great attention in the industry in recent years, solar cell technology has become the industry's recognized next-generation commercial photovoltaic industry technology because of its high photoelectric conversion efficiency, excellent performance, large cost reduction space, and good prospects for affordable Internet access.

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

For high-efficiency heterojunction cells, one of the current technical difficulties lies in 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 in the entire production process is generally below 200 °C. , In order to maintain good contact between the grid line and the TCO film layer in the printing process, only low-temperature silver paste can be used, and the drying and curing temperature is generally maintained at about 200 °C.

The existing heating method of drying and curing is to heat the entire furnace body through a resistance wire, and heat the entire cell by means of heat conduction, so as to form an ohmic contact between the slurry and the TCO layer and reduce the contact resistance.

Referring to FIG. 1 , a tower-type drying furnace is currently used for drying, and the drying reaction is carried out in a closed space. There is a heating resistance wire 2 inside the drying furnace to provide the drying temperature required for the silver paste. After the silicon wafer 1 is printed with paste (back pole, back field, positive electrode), there is silver paste on the surface, which needs to be dried and shaped in time. The internal temperature of the tower drying furnace is kept at 200°C, and the silicon wafer is supported by a pallet, and the pallet is controlled by hinge 3 to move up and down. The whole drying process requires the silicon wafer 1 to be kept at a high temperature of 200° C. for about 10 minutes in the drying furnace cavity 4 . Through the air heat conduction in the furnace, the heat of the resistance wire is conducted to the silicon wafer. After the overall temperature of the silicon wafer is heated, the slurry will also heat up, forming a basic grid line shaping process.

After the basic shaping, the silicon wafer needs to be transported to the curing furnace for curing. Referring to FIG. 2 , the curing furnace still uses the resistance wire 2 to heat the silicon wafer 1 as a whole.

This method must heat the entire silicon wafer. The amorphous silicon layer limits the upper limit of the thermal process temperature to 200°C, which leads to a long drying and curing time. It must be dried in a tower first, and then cured in a curing furnace. To a certain extent It also makes the equipment structure more complex and increases the risk of mass production equipment downtime.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present application is to provide a solar cell, a preparation method thereof, and a laser annealing device.

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

The first local heating of the back electrode printed silicon wafer;

Back-field printing is performed, and a second local heating is performed;

Perform positive electrode printing, and perform a third local heating;

The first partial heating, the second partial heating and the third partial heating are all heated by irradiating only the grid lines with a laser.

By setting the first local heating, the second local heating and the third local heating, the laser is only used to irradiate the grid line for heating; the grid line can be heated centrally, that is, only the local area of the grid line is subjected to high-temperature annealing treatment. rather than heating the entire silicon wafer. The method of the present application can obtain good ohmic contact only by heating the gate line. The method of the present application does not need to use a tower drying oven for drying and curing oven curing twice. Drying and curing can be carried out at the same time, the time is shorter, the equipment structure is simpler, and the risk of mass production equipment downtime is reduced.

The method of the present application is especially suitable for heterojunction cells, which can not only form a good ohmic contact, but also can reduce the usage of silver paste and reduce the manufacturing cost of solar cells.

For heterojunction cells, the current conventional method of drying and curing the whole silicon wafer, 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 ohmic The contact effect 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, resulting in decreased cell efficiency. This application creatively proposes that the first local heating, the second local heating and the third local heating are all heated by irradiating only the grid lines with laser, which can increase the heating temperature, break through this limitation, and not only can form a good ohmic contact, and will not cause damage to the amorphous silicon film. Increasing the heating temperature can greatly reduce the contact resistance between the gate line and the TCO and improve the cell efficiency. Further, since a good ohmic contact can be achieved at a high temperature, the usage amount of the low-temperature silver paste can be reduced. Therefore, the solution of the present application can reduce the content of the silver paste and reduce the production cost of the solar cell.

In other optional embodiments of the present application, the heating is performed by irradiating only the grid lines with laser light by relatively moving the laser light along the length direction of the grid lines to irradiate.

In other optional embodiments of the present application, when only the grid lines are irradiated with laser light for heating, the laser irradiation width is greater than or equal to the width of the grid lines.

In other optional embodiments of the present application, the laser irradiation width is greater than the width of the grid line and not greater than 10 microns.

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

In a second aspect, the present application provides a solar cell, which is prepared by using any one of the aforementioned methods for preparing a solar cell.

In a third aspect, the present application provides a laser annealing device, which is applied to the preparation method of any one of the foregoing solar cells;

The laser annealing device includes a cavity, a laser and a positioning device;

A transfer roller is arranged in the cavity for transferring 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 transfer roller, and is used to perform the first partial heating, the second partial heating or the third partial heating on the passing silicon wafer according to the grid line position data.

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

The detection component is a camera;

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

A grid line position mark is set on the surface of the silicon wafer, and the camera determines the position of the grid line by acquiring the mark.

In other optional embodiments of the present application, 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 sliding bar or the second sliding bar through the connecting rod; the roller is used to contact the side edge of the silicon wafer;

The first sliding rod and the second sliding rod are arranged opposite to each other; the first sliding rod and the second sliding rod are arranged on opposite sides of the silicon wafer, and the first sliding rod and the second sliding rod can move to be close to or away from each other, so that the roller contacts the fixed silicon wafer.

In other optional embodiments of the present application, the laser annealing device is provided with an exhaust system, and the exhaust system is arranged on the top of the cavity.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present application more clearly, the following drawings will briefly introduce the drawings that need to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the schematic diagram of existing drying tower furnace;

2 is a schematic diagram of an existing curing furnace;

3 is a schematic diagram of a laser irradiation area of a laser annealing device provided by an embodiment of the present application;

4 is a schematic structural diagram of a laser annealing apparatus provided by an embodiment of the present application;

FIG. 5 is a schematic diagram of camera detection of the laser annealing device provided by the embodiment of the present application;

FIG. 6 is a schematic diagram of a clamping component of a laser annealing apparatus provided in an embodiment of the present application.

Icon: 1-silicon wafer; 2-resistance wire; 3-hinge; 4-cavity; 10-silicon wafer; 11-grid line; 12-laser irradiation area; 100-laser annealing device; 110-cavity; 111- 112-top; 120-laser; 131-camera; 132-clamping assembly; 1321-roller; 1322-connecting rod; 1323-first sliding rod; 1324-second sliding rod;

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of the present application, but not all of the embodiments. The components of the embodiments of the present application generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

Thus, the following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the application as claimed, but is merely representative of selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of the embodiments of the present application, it should be understood that the orientations or positional relationships indicated by the terms "upper", "left", "right", "horizontal", "inner", "outer", etc. are based on the drawings. The orientation or positional relationship shown, or the orientation or positional relationship that the application product is usually placed in use, or the orientation or positional relationship that is commonly understood by those skilled in the art, is only for the convenience of describing the application and simplifying the description, not An indication or implication that the referred device or element must have, be constructed, and operate in a particular orientation is not to be construed as a limitation of the present application.

Furthermore, the terms "first", "second", etc. are only used to differentiate the description and should not be construed to indicate or imply relative importance.

In the description of the embodiments of the present application, it should also be noted that, unless otherwise expressly specified and limited, the terms "arrangement" and "connection" should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection , or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood in specific situations.

Referring to FIGS. 3 to 6 , some embodiments of the present application provide a method for preparing a solar cell, including:

The first local heating of the back electrode printed silicon wafer;

Back-field printing is performed, and a second local heating is performed;

Perform positive electrode printing, and perform a third local heating;

The first partial heating, the second partial heating and the third partial heating are all heated by irradiating only the grid lines with a laser.

By setting the first local heating, the second local heating and the third local heating, the laser is only used to irradiate the grid line for heating; the grid line can be heated centrally, that is, only the local area of the grid line is subjected to high-temperature annealing treatment. Instead of heating the entire silicon wafer. And the drying and curing can be carried out at the same time, which greatly improves the production efficiency.

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

Pastes account for a significant cost in solar cell fabrication. In conventional PERC cells, the cost of slurry accounts for more than 30% of the cost of non-silicon. 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 the heterojunction cell needs to maintain a low contact resistance, which requires more Ag content in the silver paste to achieve (relative to the higher Ag content in the paste used in conventional PERC).

However, the amorphous silicon film layer of the heterojunction cell limits the upper limit of the curing temperature, and the conventional method of heating the whole silicon wafer cannot exceed 200 °C (there may be small 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, resulting in decreased cell efficiency. This application creatively proposes that the first local heating, the second local heating and the third local heating are all heated by irradiating only the grid lines with laser, which breaks through this limitation and can not only form a good ohmic contact, but also does not Damage to the amorphous silicon film.

Further, in some embodiments of the present application, the temperatures of the first partial heating, the second partial heating, and the third partial heating are all between 250°C and 300°C.

The inventor found that the contact resistance between the gate line and the TCO can be greatly reduced by setting the temperature of the first local heating, the second local heating and the third local heating at 250°C to 300°C, and the efficiency is the highest. The amorphous silicon film will not cause damage, and can repair the defects in the amorphous silicon film to a certain extent. Since the method of the present application can locally heat the gate line at a relatively high temperature to achieve low contact resistance, it is expected to reduce the Ag content in the paste and to reduce the cost of the paste.

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

Further, in some embodiments of the present application, the temperatures of the first partial heating, the second partial heating, and the third partial heating may be the same or different. Exemplarily, the temperatures of the first partial heating, the second partial heating, and the third partial heating are all 258°C, 268°C, 275°C or 278°C. Alternatively, the temperatures of the first partial heating, the second partial heating, and the third partial heating are respectively 256°C, 266°C or 276°C.

Further, the solution of the present application only needs to add a laser annealing device, and does not need to add other additional processes. It has good matching with the current production line and has a wider range of applications.

Further, according to the solution of the present application, the laser of the laser annealing device only needs one wavelength, which does not involve the processing of the TCO layer or the amorphous silicon layer, and hardly affects the TCO layer and the amorphous silicon. Further, in the solution of the present application, only the gate lines are annealed individually, and the specific wavelength parameters can be determined according to different slurries and previous processes.

It should also be noted that the preparation method of a solar cell provided in this 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.

In addition to applying different types of battery printing lines, the solution of this application can also be applied to reduce costs. For HIT batteries, using this solution can reduce the Ag content in the paste, and even for Cu electroplating technology, using this solution can also The effect of reducing contact resistance and improving battery efficiency can be achieved. And for the more popular silver-copper paste and laser transfer printing, this solution can also be applied, the difference is that the setting of the laser parameters and the accuracy requirements can be adjusted according to the actual situation.

Further, in some embodiments of the present application, the preparation method of the above-mentioned solar cell comprises the following steps:

Step S1 , performing local heating on the silicon wafer after the back electrode printing for the first time.

The above-mentioned back electrode printed silicon wafer can be obtained by using the current conventional process. Made by printing the back electrode on a silicon wafer.

Further, the first local heating of the back electrode printed silicon wafer is to use laser light only to irradiate the grid lines for heating.

Further, using the laser to irradiate only the grating lines for heating is to irradiate the laser while relatively moving along the length direction of the grating lines.

Further, when only the grid lines are irradiated with laser light for heating, the laser irradiation width is greater than or equal to the width of the grid lines.

Further, in some embodiments of the present application, the laser irradiation width is greater than the gate line width, and not greater than 10 microns.

Exemplarily, referring to FIG. 3 , in the embodiment shown in FIG. 3 , a plurality of gate lines 11 are sequentially arranged on the silicon wafer 10 , and the dashed box in the figure exemplarily shows the laser irradiation area 12 . It can be seen that the laser irradiation direction is consistent with the length direction of the grid lines 11 . The laser irradiation width is slightly wider than the gate line width. In this case, the laser light can completely irradiate the grid lines, heat curing and annealing the grid lines. Through long-term research by the inventor, setting the laser irradiation width to be greater than the width of the grid line and not greater than 10 microns can not only effectively ensure that the temperature of the laser-heated grid line is increased to 250°C to 300°C. Concentrated heating of the grid line can realize high-temperature annealing treatment on the local area of the grid line. Within a certain range, high temperature is conducive to forming a good ohmic contact between the grid line and the TCO, reducing contact resistance and improving battery efficiency. And will not cause damage to the TCO layer on the silicon wafer.

Illustratively, the laser shot 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.

Further, the first local heating by only irradiating the grid lines with laser is the heating by using the laser annealing device 100 .

Further, referring to FIG. 5 , the laser annealing apparatus 100 includes a cavity 110 , a laser 120 and a positioning device.

Further, a transmission device 111 is provided in the cavity 110 for transmitting the silicon wafer 10 .

Optionally, in some embodiments of the present application, the above-mentioned transmission device 111 is a crawler. It can stably and quickly transfer the silicon wafer to the position to be heated, which provides a favorable guarantee for the subsequent laser to locally heat the grid lines on the silicon wafer.

Further, the positioning device is used for fixing the silicon wafer 10, positioning the gate line position on the silicon wafer 10, and transmitting the gate line position data.

Further, the laser 120 is placed above the transmission device 111, and is used to locally heat the passing silicon wafer 10 for the first time according to the grid line position data.

Further, the positioning device includes a detection component.

In some embodiments of the present application, referring to FIG. 5 , the above-mentioned detection component is the camera 131 .

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

The camera 131 takes pictures of the silicon wafer, and obtains the positions of the two long sides of the gate lines on the silicon wafer, so as to realize the positioning of the gate lines.

In some embodiments of the present application, a grid line position mark is provided on the surface of the silicon wafer 10, and the camera 131 determines the position of the grid line by acquiring the mark.

The camera 131 takes pictures of the silicon wafer to obtain the position of the mark on the silicon wafer, so as to realize the positioning of the grid lines.

Further, the positioning device includes a clamping assembly 132 .

Further, referring to FIG. 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 .

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

Further, the first sliding rod 1323 and the second sliding rod 1324 are arranged opposite to each other; the first sliding rod 1323 and the second sliding rod 1324 are arranged on opposite sides of the silicon wafer 10, and the first sliding rod 1323 and the second sliding rod 1324 The rollers 1324 can be moved close to each other or away from each other, so that the rollers 1321 contact and fix the silicon wafer 10 .

Further, the roller 1321 can rotate freely, so as to facilitate contacting and fixing the silicon wafer.

The clamping component 132 clamps and fixes the silicon wafer, the camera takes pictures, and after confirming the position of the grid lines on the silicon wafer, data is sent to the laser, and the laser locally heats the grid lines.

Further, the laser annealing apparatus 100 is provided with an exhaust system 140 , and the exhaust system 140 is arranged on the top 112 of the cavity 110 .

By arranging the exhaust system 140 , the harmful gas in the cavity 110 can be discharged in time, so as to ensure the working environment in the cavity 110 .

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

Exemplarily, referring to FIGS. 4-6 , when the laser annealing device 100 of the present application is used for local laser heating, the silicon wafer 10 is driven by the crawler belt and passes through the laser 120 in the cavity 110 at a certain speed. The laser 120 can align the grid lines. The local area is heated, and the top is provided with an exhaust system 140 to remove harmful gases. Since the laser 120 only heats the gate lines on the surface of the silicon wafer 10 and does not heat the entire silicon wafer 10, the temperature can be set to exceed 200°C without damaging the amorphous silicon layer. Setting the temperature between 250°C and 300°C can greatly improve the contact resistance between the gate line and the TCO to achieve the best cell efficiency.

In step S2, back field printing is performed, and a second local heating is performed.

The backfield printing can be performed by using a conventional method in the art, which will not be repeated here.

Further, the second local heating is also performed by irradiating only the grid lines with laser light; the temperature of the second local heating is 250°C to 300°C.

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. Illustratively, the temperature of the second localized heating is 258°C, 268°C, 275°C, or 278°C.

Further, the second local heating is also irradiated by relatively moving the laser along the length direction of the grid lines.

Further, the second local heating is also to irradiate the laser along the length direction of the grid line. The laser irradiation width is greater than or equal to the width of the grid line.

Further, in some embodiments of the present application, the laser irradiation width is greater than the gate line width, and not greater than 10 microns.

Illustratively, the laser shot 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.

The effect of the second local heating can be referred to FIG. 3 . The laser irradiation direction is consistent with the longitudinal direction of the grid lines 11 . The laser irradiation width is slightly wider than the gate line width.

Further, the second local heating may be performed by using the laser annealing apparatus 100 in step S1.

Step S3, performing positive electrode printing, and performing local heating for the third time;

The printing of the positive electrode can be performed by using a conventional method in the art, which will not be repeated here.

Further, the third local heating is also performed by irradiating only the grid lines with laser light; the temperature of the third local heating is 250°C to 300°C.

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. Illustratively, the temperature of the second localized heating is 258°C, 268°C, 275°C, or 278°C.

Further, the third local heating is also irradiated by relatively moving the laser along the length of the grid line.

Further, the third local heating is also performed by relatively moving the laser along the length direction of the grid line to irradiate the laser irradiation width greater than or equal to the width of the grid line.

Further, in some embodiments of the present application, the laser irradiation width is greater than the gate line width, and not greater than 10 microns.

Illustratively, the laser shot 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.

The effect of the third local heating can be referred to FIG. 3 . The laser irradiation direction is consistent with the longitudinal direction of the grid lines 11 . The laser irradiation width is slightly wider than the gate line width.

Further, the third local heating may be performed by using the laser annealing apparatus 100 in step S1.

It should be noted that the other preparation processes are the same as the conventional solar cell manufacturing processes, and will not be repeated here.

Some embodiments of the present application provide a solar cell, which is prepared by using the method for preparing a solar cell in any of the foregoing embodiments.

Some embodiments of the present application provide a laser annealing device, which is applied to the method for preparing a solar cell according to any of the foregoing embodiments.

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

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims (10)

1. A method for manufacturing a solar cell, comprising:

carrying out first local heating on the silicon wafer after back electrode printing;

carrying out back surface field printing and carrying out second local heating;

performing positive electrode printing and performing third local heating;

the first local heating, the second local heating and the third local heating are all heating by only irradiating the grid lines with laser.

2. The method for manufacturing a solar cell according to claim 1,

the laser is used for irradiating the grid line only, and the laser is moved relatively along the length direction of the grid line for irradiation.

3. The method for manufacturing a solar cell according to claim 1,

when the grid line is only irradiated by laser for heating, the laser irradiation width is larger than or equal to the width of the grid line.

4. The method for manufacturing a solar cell according to claim 3,

the laser irradiation width is larger than the width of the grid line and not larger than 10 microns.

5. The method for manufacturing a solar cell according to claim 1,

the temperatures of the first local heating, the second local heating and the third local heating are all between 250 and 300 ℃.

6. A solar cell, characterized in that it is produced by the method for producing a solar cell according to any one of claims 1 to 5.

7. A laser annealing device is characterized by being applied to the preparation method of the solar cell of any one of claims 1 to 5;

the laser annealing device comprises a cavity, a laser and a positioning device;

a transmission roller is arranged in the cavity and used for transmitting the silicon wafer;

the positioning device is used for fixing a silicon wafer, positioning the position of a grid line on the silicon wafer and transmitting data of the position of the grid line;

the laser is arranged above the transmission roller and used for carrying out the first local heating, the second local heating or the third local heating on the passing silicon wafer according to the grid line position data.

8. The laser annealing device according to claim 7,

the positioning device comprises a detection component;

the detection component is a camera;

the camera determines the position of the grid line by acquiring two long edges of the grid line; or

And arranging a grid line position mark on the surface of the silicon wafer, and determining the position of the grid line by the camera through acquiring the mark.

9. The laser annealing device according to claim 7,

the positioning device comprises a clamping assembly;

the clamping assembly comprises a roller, a connecting rod, a first sliding rod and a second sliding rod;

the roller is connected to the first sliding rod or the second sliding rod through the connecting rod; the roller is used for contacting the side edge of the silicon wafer;

the first slide bar and the second slide bar are oppositely arranged; the first sliding rod and the second sliding rod are used for being arranged on two opposite sides of the silicon wafer, and the first sliding rod and the second sliding rod can move to be close to each other or be away from each other, so that the rollers can contact and fix the silicon wafer.

10. The laser annealing device according to claim 7,

the laser annealing device is provided with an air exhaust system, and the air exhaust system is arranged at the top of the cavity.

Images