A sintering method of an N-type TOPCon cell and a sintering furnace for sintering of an N-type TOPCon cell

Abstract

The present application relates to the technical field of N-type TOPCon cell, and particularly relates to a sintering method of N-type TOPCon cell and a sintering furnace for N-type TOPCon cell. The present application provides a sintering method of N-type TOPCon cell, comprising the following steps: conveying the N-type TOPCon cell to a sintering area, and performing lamp tube heating on the cell while performing laser scanning heating treatment on the front surface of the cell; the temperature of the front surface of the cell is 50-80 DEG C higher than that of the back surface; the front surface and the back surface of the N-type TOPCon cell are both coated with silver paste. The sintering method can make the front surface and the back surface of the N-type TOPCon cell have good sintering effect, and finally make the prepared N-type TOPCon cell have good cell efficiency.

Description

Technical Field

[0001] This invention relates to the field of N-type TOPCon battery technology, and more particularly to a sintering method for N-type TOPCon batteries and a sintering furnace for sintering N-type TOPCon batteries. Background Technology

[0002] Currently, N-type TOPCon cells (tunnel-oxide-passivated-contact cells) are highly favored due to their excellent power generation performance. Compared with traditional PERC cells, they have an ultra-thin tunnel oxide layer and a polycrystalline silicon layer added to the back.

[0003] During the metallization process, both the front and back electrodes of TOPCon require silver paste. Considering factors such as reducing ohmic contact resistance, the silver paste used on the emitter side (front) of N-type cells is usually doped with aluminum. Therefore, the front side requires a higher sintering temperature than the back side. The existing sintering process involves slowly heating both sides with a heating lamp. As a result, the sintering temperature of the front and back sides is the same, which can easily lead to poor contact performance between the silver-aluminum paste on the front side and silicon, and the silver paste on the back side puncturing the polycrystalline silicon, thus affecting the cell efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a sintering method for N-type TOPCon batteries and a sintering furnace for N-type TOPCon batteries. The sintering method enables good sintering results on both sides of the N-type TOPCon battery, ultimately resulting in N-type TOPCon batteries with good efficiency.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a sintering method for N-type TOPCon batteries, comprising the following steps:

[0007] While the N-type TOPCon solar cell is being heated by lamps in the sintering zone, laser scanning is applied to the front side of the solar cell.

[0008] The front temperature of the battery cell is 50-80°C higher than the back temperature;

[0009] The N-type TOPCon solar cell is coated with silver paste on both the front and back sides.

[0010] Preferably, the temperature of the back side of the battery cell is 700–730°C.

[0011] Preferably, the front surface temperature of the battery cell is 750–800°C.

[0012] Preferably, the conveying speed of the battery cells is 250 mm / s.

[0013] Preferably, the laser scanning process involves scanning back and forth at a speed of 10–20 m / s;

[0014] The laser scanning process has a spot diameter of 2–10 mm and a wavelength of 300–1100 nm.

[0015] The present invention provides a sintering furnace for N-type TOPCon cells, including a cell transfer device, a sintering furnace, a photoelectric detector, a transparent window, and a laser scanner;

[0016] The transparent window is located at the top of the sintering furnace;

[0017] The laser scanner is positioned to illuminate the transparent window.

[0018] Preferably, the battery cell conveying device is a transmission roller.

[0019] Preferably, the photoelectric detector is located next to the laser scanner.

[0020] Preferably, the heating device for the sintering furnace is a heating lamp tube;

[0021] The heating lamps are located on the upper and lower sides of the battery cells and are distributed inside the sintering furnace.

[0022] This invention provides a sintering method for N-type TOPCon solar cells, comprising the following steps: simultaneously heating the N-type TOPCon solar cell in a sintering zone using lamps and applying laser scanning to the front side of the solar cell; the front temperature of the solar cell being 50-80°C higher than the back temperature; and both the front and back sides of the N-type TOPCon solar cell being coated with silver paste. In conventional sintering, while higher sintering temperatures result in better sintering of the front silver paste and better contact with silicon, the back silver paste is prone to burning through the tunneling oxide layer, leading to poor passivation. Lower sintering temperatures result in better sintering of the back silver paste without burning through the oxide layer, but incomplete sintering of the front silver paste, resulting in a poorer effect. Therefore, conventional sintering processes struggle to achieve optimal sintering temperatures while simultaneously maximizing the sintering effect of the paste on both the front and back sides. The laser scanning process can quickly bring the front side of the solar cell to a higher temperature (50-80°C higher than the back side) to help the silver paste on the front side burn through the passivation layer in the N-type TOPCon cell, ensuring contact performance with silicon. At the same time, the laser scanning process reaches the highest temperature, which can reduce the irradiation temperature of the heating lamp and save energy. Attached Figure Description

[0023] Figure 1This is a schematic diagram of the sintering furnace of the present invention, wherein 1-N-type TOPCon battery, 2-battery cell transfer device, 3-top of sintering furnace, 4-laser scanner, 5-photoelectric detector head, 6-side wall of sintering furnace, 7-transparent window, and 8-heating lamp tube. Detailed Implementation

[0024] This invention provides a sintering method for N-type TOPCon batteries, comprising the following steps:

[0025] While the N-type TOPCon solar cell is being heated by lamps in the sintering zone, laser scanning is applied to the front side of the solar cell.

[0026] The front temperature of the battery cell is 50-80°C higher than the back temperature;

[0027] The N-type TOPCon solar cell is coated with silver paste on both the front and back sides.

[0028] In this invention, unless otherwise specified, all materials or equipment are commercially available products well known to those skilled in the art.

[0029] In this invention, the front side of the N-type TOPCon solar cell is preferably coated with aluminum-doped silver paste, and the aluminum content in the aluminum-doped silver paste is preferably 5 wt%; the back side of the N-type TOPCon solar cell is preferably coated with undoped silver paste.

[0030] This invention does not impose any special limitations on the structure of the N-type TOPCon solar cell; any structure well-known to those skilled in the art can be used. In the embodiments of this invention, the structure of the N-type TOPCon solar cell includes a passivation / antireflection film, a passivation layer, a p-type emitter, an n-type silicon substrate, an ultrathin tunneling layer, an n-type polycrystalline silicon thin film, and an antireflection film, which are sequentially stacked.

[0031] In this invention, the front temperature of the battery cell is 50-80°C higher than the back temperature, preferably 55-75°C, and more preferably 60-70°C.

[0032] In this invention, the temperature of the back side of the battery cell is preferably 700-730°C, more preferably 705-725°C, and most preferably 710-720°C.

[0033] In this invention, the front surface temperature of the battery cell is preferably 750-800°C, more preferably 760-790°C, and most preferably 770-780°C.

[0034] In this invention, the preferred conveying speed of the battery cells is 250 mm / s.

[0035] In this invention, the laser scanning process is preferably performed by scanning back and forth at a speed of 10 to 20 m / s; the laser spot diameter is preferably 2 to 10 mm, more preferably 4 to 8 mm, and most preferably 5 to 6 mm; the wavelength is preferably 300 to 1100 nm, more preferably 500 to 1000 nm, and most preferably 600 to 950 nm.

[0036] This invention provides a sintering furnace for sintering N-type TOPCon cells, including a cell transfer device, a sintering furnace, a photoelectric detector, a transparent window, and a laser scanner;

[0037] The transparent window is located at the top of the sintering furnace;

[0038] The laser scanner is positioned to illuminate the transparent window.

[0039] In one embodiment of the present invention, the transparent window has dimensions of 100mm * 50mm. The material of the transparent window is high-temperature resistant quartz glass; preferably, the high-temperature resistant quartz glass is polished and coated sequentially; the present invention does not impose any special limitations on the polishing and coating processes, and adopts processes well known to those skilled in the art to ensure that the transmittance of the transparent window exceeds 97%.

[0040] In one embodiment of the present invention, the battery cell conveying device is a transmission roller.

[0041] In one embodiment of the present invention, the photoelectric detector is located next to the laser scanner.

[0042] In one embodiment of the present invention, the heating device of the sintering furnace is a heating lamp tube;

[0043] The heating lamps are located on the upper and lower sides of the battery cells and are distributed inside the sintering furnace.

[0044] In this invention, the preferred method of using the sintering furnace is as follows: the N-type TOPCon solar cell is placed on the solar cell transport device, with the front side of the N-type TOPCon solar cell facing upwards, and is transported into the sintering furnace until it reaches directly below the photoelectric detector head to obtain the position of the solar cell. The N-type TOPCon solar cell continues to be transported at a constant speed, and the laser scanner is turned on to scan the front side of the N-type TOPCon solar cell so that the front side of the N-type TOPCon solar cell is scanned evenly.

[0045] The sintering method and sintering furnace of the N-type TOPCon battery provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] The structure of the sintering furnace (e.g.) Figure 1 (As shown): Includes a solar cell transport device, a sintering furnace, a photoelectric detector, a transparent window, and a laser scanner; the transparent window is located at the top of the sintering furnace; the laser scanner is positioned at the transparent window. The transparent window has dimensions of 100mm * 50mm. The transparent window has a transmittance of 97% and is made of high-temperature resistant quartz glass; the solar cell transport device is a drive roller; the photoelectric detector is located next to the laser scanner; the heating device for the sintering furnace is a heating lamp; the heating lamps are located on the upper and lower sides of the solar cells and are distributed inside the sintering furnace.

[0048] The structure of the N-type TOPCon solar cell is as follows: from the front to the back, a passivation / antireflection film, a passivation layer, a p-type emitter, an n-type silicon substrate, an ultrathin tunneling layer, an n-type polycrystalline silicon thin film, and an antireflection film are stacked sequentially. The front of the N-type TOPCon solar cell is coated with aluminum-doped silver paste, and the aluminum doping content in the aluminum-doped silver paste is 5wt%. The back of the N-type TOPCon solar cell is coated with silver paste.

[0049] N-type TOPCon solar cells (182mm x 182mm) are placed on a cell transport device with their front side facing up and transported into the sintering furnace until they reach directly below a photodetector to obtain the cell's position. The N-type TOPCon solar cells continue to be transported at a uniform speed (250mm / s). The ambient temperature is controlled at 700℃ by the heating lamps. The laser scanner is activated to scan the front side of the N-type TOPCon solar cells (scanning back and forth at a speed of 20m / s; the laser scanning spot diameter is 2mm and the wavelength is 915nm), ensuring that the front side of the N-type TOPCon solar cells is uniformly scanned and that the front temperature of the N-type TOPCon solar cells reaches 780℃. During this process, the back side of the N-type TOPCon solar cells is heated to 705℃ by the heating lamps in the sintering furnace. The scanning time for each solar cell is 1 second, resulting in sintered N-type TOPCon solar cells.

[0050] Example 2

[0051] The structure of the sintering furnace (e.g.) Figure 1(As shown): Includes a solar cell transport device, a sintering furnace, a photoelectric detector, a transparent window, and a laser scanner; the transparent window is located at the top of the sintering furnace; the laser scanner is positioned at the transparent window. The transparent window has dimensions of 100mm * 50mm. The transparent window has a transmittance of 97% and is made of high-temperature resistant quartz glass; the solar cell transport device is a drive roller; the photoelectric detector is located next to the laser scanner; the heating device for the sintering furnace is a heating lamp; the heating lamps are located on the upper and lower sides of the solar cells and are distributed inside the sintering furnace.

[0052] The structure of the N-type TOPCon solar cell is as follows: from the front to the back, a passivation / antireflection film, a passivation layer, a p-type emitter, an n-type silicon substrate, an ultrathin tunneling layer, an n-type polycrystalline silicon thin film, and an antireflection film are stacked sequentially. The front of the N-type TOPCon solar cell is coated with aluminum-doped silver paste, and the aluminum doping content in the aluminum-doped silver paste is 5wt%. The back of the N-type TOPCon solar cell is coated with silver paste.

[0053] N-type TOPCon solar cells (182mm x 182mm) are placed on a cell transport device with their front side facing up and transported into the sintering furnace until they reach directly below a photodetector to obtain the cell's position. The N-type TOPCon solar cells continue to be transported at a constant speed (250mm / s). The laser scanner is activated to scan the front side of the N-type TOPCon solar cells (scanning back and forth at a speed of 20m / s; the laser scanning spot diameter is 4mm and the wavelength is 915nm), ensuring that the front side of the N-type TOPCon solar cells is uniformly scanned and that the front temperature of the N-type TOPCon solar cells reaches 775℃. During this process, the back side of the N-type TOPCon solar cells is heated to 725℃ by heating lamps in the sintering furnace. The scanning time for each solar cell is 0.5 seconds, resulting in sintered N-type TOPCon solar cells.

[0054] Example 3

[0055] The structure of the sintering furnace (e.g.) Figure 1 (As shown): Includes a solar cell transport device, a sintering furnace, a photoelectric detector, a transparent window, and a laser scanner; the transparent window is located at the top of the sintering furnace; the laser scanner is positioned at the transparent window. The transparent window has dimensions of 100mm * 50mm. The transparent window has a transmittance of 97% and is made of high-temperature resistant quartz glass; the solar cell transport device is a drive roller; the photoelectric detector is located next to the laser scanner; the heating device for the sintering furnace is a heating lamp; the heating lamps are located on the upper and lower sides of the solar cells and are distributed inside the sintering furnace.

[0056] The structure of the N-type TOPCon solar cell is as follows: from the front to the back, a passivation / antireflection film, a passivation layer, a p-type emitter, an n-type silicon substrate, an ultrathin tunneling layer, an n-type polycrystalline silicon thin film, and an antireflection film are stacked sequentially. The front of the N-type TOPCon solar cell is coated with aluminum-doped silver paste, and the aluminum doping content in the aluminum-doped silver paste is 5wt%. The back of the N-type TOPCon solar cell is coated with silver paste.

[0057] N-type TOPCon solar cells (182mm x 182mm) are placed on a cell transport device with their front side facing up and transported into the sintering furnace until they reach directly below a photodetector to obtain the cell's position. The N-type TOPCon solar cells continue to be transported at a constant speed (250mm / s), while a laser scanner is activated to scan the front side of the N-type TOPCon solar cells (scanning back and forth at 10m / s; the laser scanning spot diameter is 2mm and the wavelength is 1080nm). This ensures that the front side of the N-type TOPCon solar cells is uniformly scanned and reaches a temperature of 780°C. During this process, the back side of the N-type TOPCon solar cells is heated to 720°C by heating lamps in the sintering furnace. The scanning time for each cell is 0.5 seconds, resulting in sintered N-type TOPCon solar cells.

[0058] Comparative Example 1

[0059] Referring to Example 1, the difference is that laser scanning is not performed.

[0060] Test case

[0061] The front contact resistance of the sintered N-type TOPCon solar cells described in Example 1 and Comparative Example 1 was tested using a TLM-SCAN+ multi-functional solar cell grid contact resistance tester. The front contact resistance of the N-type TOPCon solar cell described in Comparative Example 1 was 10 mΩcm. 2 The front contact resistance of the N-type TOPCon solar cell described in Example 1 is 1.5 mΩcm. 2 Therefore, the sintering treatment described in this invention can improve the sintering effect of the front silver paste and ensure sufficient contact with silicon.

[0062] The efficiency of the N-type TOPCon solar cells after sintering treatment as described in Example 1 and Comparative Example 1 was tested using a solar cell IV tester. The efficiency of the N-type TOPCon solar cell in Comparative Example 1 was 23.5%, and the efficiency of the N-type TOPCon solar cell in Example 1 was 24%. This shows that the sintering process described in this invention fully ensures the sintering effect of the front silver paste, and also reduces the heating temperature required for the entire furnace body, thereby reducing energy consumption.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A sintering method for an N-type TOPCon battery, characterized in that, The sintering method is carried out in a sintering furnace for sintering N-type TOPCon cells. The sintering furnace for sintering N-type TOPCon cells includes a cell transfer device, a sintering zone, a photoelectric detector, a transparent window, and a laser scanner. The heating device for the sintering zone is a heating lamp. The heating lamp is located on the upper and lower sides of the cell and is distributed within the sintering zone. The transparent window is located at the top of the sintering furnace; The laser scanner is positioned to illuminate the transparent window. The sintering method includes the following steps: The N-type TOPCon solar cell is placed on the solar cell transport device and transported to the sintering zone with the front side facing up until it reaches directly below the photoelectric detection head to obtain the position of the N-type TOPCon solar cell. The N-type TOPCon solar cell continues to be transported at a constant speed. The laser scanner is turned on to scan the front side of the N-type TOPCon solar cell so that the front side of the N-type TOPCon solar cell is scanned evenly. At the same time, the N-type TOPCon solar cell is heated by the heating lamp tube in the sintering zone. The front temperature of the N-type TOPCon solar cell is 50-80°C higher than the back temperature; the front temperature of the solar cell is 750-800°C; and the back temperature of the solar cell is 700-730°C. The N-type TOPCon solar cell is coated with silver paste on both the front and back sides; The conveying speed of the N-type TOPCon solar cell is 250 mm / s; The laser scanning process involves scanning back and forth at a speed of 10~20m / s. The laser scanning process has a spot diameter of 2-10 mm and a wavelength of 300-1100 nm.

2. The sintering method as described in claim 1, characterized in that, The battery cell transport device is a transmission roller.

3. The sintering method as described in claim 1, characterized in that, The photoelectric detector head is located next to the laser scanner.

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