Solar cell, photovoltaic module and preparation method thereof

Abstract

The invention discloses a solar cell, a photovoltaic module and a preparation method thereof. The solar cell may include: a silicon substrate having a textured first main surface; an emitter, a passivation layer and a front antireflection layer are laminated on the first main surface from inside to outside; a first silver-aluminum gate line arranged on the front antireflection layer, wherein the first silver-aluminum gate line is in ohmic contact with the emitter; in the textured structure, a metalized area and a non-metalized area corresponding to the first silver-aluminum gate line meet at least one of the following conditions: a first projection coefficient of the metalized area is greater than a second projection coefficient of the non-metalized area except the metalized area; the roughness of the metalized region is greater than that of the non-metalized region; the top of the suede area corresponding to the metalized area is of a plane structure or a cambered surface structure, and the top of the suede area corresponding to the non-metalized area is of a pointed structure; the metalized region is of a planar structure, and the non-metalized region is of a pyramid structure. The structure can improve the reliability of the solar cell.

Description

Technical Field

[0001] The invention relates to a solar cell, a photovoltaic module and a preparation method thereof. Background Art

[0002] For the front of TOPCon (Tunnel Oxide Passivating Contact) cells, silver-aluminum paste is generally used because silver-aluminum paste has relatively good burn-through properties. During the process of sintering silver-aluminum paste to form grid lines, silver-aluminum paste can pass through the anti-reflection layer and the passivation layer to form electrical contact with the front emitter. However, since a large number of silver-aluminum spikes will be generated during the sintering process of silver-aluminum paste, the silver-aluminum spikes are easily damaged by water vapor or acid, resulting in the destruction of the contact between the grid lines formed by the silver-aluminum paste and the emitter. Then, once the grid lines formed by the silver-aluminum paste come into contact with water vapor or acid (the acid is generally produced by the hydrolysis of the encapsulation film of the photovoltaic module during the aging process or the acidic material of the film additive in the encapsulation film), the conductivity of the entire grid line will be destroyed, resulting in a relatively large corrosion risk for TOPCon cells, and low reliability and stability. Summary of the invention

[0003] In view of this, the present invention provides a solar cell, a photovoltaic module and a preparation method thereof. The solar cell increases the silver-silicon alloy points formed by the first silver-aluminum grid line and the metallized area by changing the structure of the metallized area corresponding to the first silver-aluminum grid line in the velvet structure, thereby improving the corrosion resistance of the first silver-aluminum grid line and improving the reliability of the solar cell.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

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

[0006] The first main surface is a silicon substrate with a suede structure;

[0007] An emitter, a passivation layer and a front anti-reflection layer are stacked from inside to outside on the first main surface of the silicon substrate and matched with the velvet structure, wherein the emitter, the passivation layer and the front anti-reflection layer correspond to the front side of the solar cell;

[0008] and first silver-aluminum grid lines arranged at intervals on the front anti-reflection layer, wherein the first silver-aluminum grid lines are in ohmic contact with the emitter;

[0009] In the velvet structure, the metallized area corresponding to the first silver-aluminum grid line and the non-metallized area outside the metallized area meet at least one of the following conditions:

[0010] Condition 1: The first projection coefficient of the metallized area is greater than the second projection coefficient of the non-metallized area outside the metallized area, wherein the first projection coefficient is obtained by dividing the surface area of ​​the metallized area by the projection area of ​​the metallized area on the horizontal plane, and the second projection coefficient is obtained by dividing the surface area of ​​the non-metallized area by the projection area of ​​the non-metallized area on the horizontal plane;

[0011] Condition 2: The roughness of the metallized area is greater than the roughness of the non-metallized area;

[0012] Condition 3: the top of the suede area corresponding to the metallized area is a flat structure or a curved structure, and the top of the suede area corresponding to the non-metallized area is a pointed structure;

[0013] Condition 4: the metallized area is a planar structure, and the non-metallized area is a pyramid structure.

[0014] In a second aspect, an embodiment of the present invention provides a photovoltaic module, including:

[0015] The solar cell provided by the above-mentioned first aspect embodiment or the cell slice cut from the solar cell provided by the above-mentioned first aspect embodiment.

[0016] In a third aspect, an embodiment of the present invention provides a method for preparing a solar cell provided in the embodiment of the first aspect, comprising:

[0017] Step 1: preparing a velvet structure on a first main surface of a silicon substrate, wherein the velvet structure has metallized areas and non-metallized areas arranged alternately;

[0018] Step 2, sequentially stacking an emitter, a passivation layer and a front anti-reflection layer matching the suede structure on the first main surface of the silicon substrate, wherein the emitter, the passivation layer and the front anti-reflection layer correspond to the front side of the solar cell;

[0019] Step 3, placing silver-aluminum paste on the front anti-reflection layer corresponding to the metallized area, and pre-sintering, and forming a first silver-aluminum grid line by laser excitation of local carriers combined with a bias voltage, wherein the first silver-aluminum grid line is in ohmic contact with the emitter;

[0020] In the suede structure, the metallized area and the non-metallized area meet at least one of the following conditions:

[0021] Condition 1: The first projection coefficient of the metallized area is greater than the second projection coefficient of the non-metallized area outside the metallized area, wherein the first projection coefficient is obtained by dividing the surface area of ​​the metallized area by the projection area of ​​the metallized area on the horizontal plane, and the second projection coefficient is obtained by dividing the surface area of ​​the non-metallized area by the projection area of ​​the non-metallized area on the horizontal plane;

[0022] Condition 2: The roughness of the metallized area is greater than the roughness of the non-metallized area;

[0023] Condition 3: the top of the suede area corresponding to the metallized area is a flat structure or a curved structure, and the top of the suede area corresponding to the non-metallized area is a pointed structure;

[0024] Condition 4: the metallized area is a planar structure, and the non-metallized area is a pyramid structure.

[0025] The technical solution of the first aspect of the above invention has the following advantages or beneficial effects:

[0026] The solar cell provided by the embodiment of the present invention has a velvet structure corresponding to the front side of the solar cell, in which the metallized area corresponding to the first silver-aluminum grid line and the non-metallized area outside the metallized area meet at least one of the following conditions: Condition 1, the first projection coefficient of the metallized area is greater than the second projection coefficient of the non-metallized area outside the metallized area; Condition 2, the roughness of the metallized area is greater than the roughness of the non-metallized area; Condition 3, the top of the velvet area corresponding to the metallized area is a flat structure or a curved structure, and the top of the velvet area corresponding to the non-metallized area is a pointed structure; Condition 4, the metallized area is a flat structure, and the non-metallized area is a curved structure. The metallized area is a pyramid structure; even if the first silver-aluminum grid line needs to pass through the passivation layer and the front anti-reflection layer, the metallized area can effectively increase the silver-silicon alloy contact sites formed by the silver in the first silver-aluminum grid line and the silicon in the emitter. The increase of the silver-silicon alloy contact sites can improve the corrosion resistance of the first silver-aluminum grid line. In addition, even if corrosion holes appear in the first silver-aluminum grid line in the area outside the silver-silicon alloy contact sites, due to the large number of silver-silicon alloy contact sites, the first silver-aluminum grid line can still maintain good conductivity, thereby ensuring the current transmission of the first silver-aluminum grid line, improving the corrosion resistance of the first silver-aluminum grid line, and thus improving the reliability of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a partial cross-sectional structure of a first solar cell in the prior art;

[0028] Figure 2 It is a schematic diagram of a partial cross-sectional structure of a first solar cell in the prior art;

[0029] Figure 3 is a partial cross-sectional structural schematic diagram of a first velvet structure of a silicon substrate according to an embodiment of the present invention;

[0030] Figure 4 is a schematic diagram of a partial cross-sectional structure of a solar cell having a silicon substrate with a first velvet structure according to an embodiment of the present invention;

[0031] Figure 5 is a partial cross-sectional structural schematic diagram of a second velvet structure of a silicon substrate according to an embodiment of the present invention;

[0032] Figure 6 is a schematic diagram of a partial cross-sectional structure of a solar cell having a silicon substrate with a second velvet structure according to an embodiment of the present invention;

[0033] Figure 7 is a partial cross-sectional structural schematic diagram of a third velvet structure of a silicon substrate according to an embodiment of the present invention;

[0034] Figure 8 is a schematic diagram of a partial cross-sectional structure of a solar cell having a silicon substrate with a third velvet structure according to an embodiment of the present invention;

[0035] Fig. 9 is a partial cross-sectional structural schematic diagram of a fourth velvet structure of a silicon substrate according to an embodiment of the present invention;

[0036] Fig.10 is a schematic diagram of a partial cross-sectional structure of a solar cell having a silicon substrate with a fourth velvet structure according to an embodiment of the present invention;

[0037] Fig.11 is a partial cross-sectional structural schematic diagram of a fifth velvet structure of a silicon substrate according to an embodiment of the present invention;

[0038] Fig.12 is a schematic diagram of a partial cross-sectional structure of a solar cell having a silicon substrate with a fifth velvet structure according to an embodiment of the present invention;

[0039] Fig.13 It is a schematic diagram of the main process of the method for preparing a solar cell according to an embodiment of the present invention.

[0040] The reference numerals are as follows:

[0041] 10-silicon substrate; 11-metallized area; 12-non-metallized area; 20-emitter; 30-passivation layer; 40-front anti-reflection layer; 50-first silver-aluminum grid line; 51-silver-silicon alloy contact site; 60-tunneling oxide layer; 70-doped polysilicon layer; 80-back anti-reflection layer; 90-second silver-aluminum grid line. DETAILED DESCRIPTION

[0042] like Figure 1 As shown, the velvet structure on the front of the existing TOPCon solar cell is a pyramid velvet structure with the same bottom width of about 10μm and height of about 10μm in both the metallized area and the non-metallized area. Research has found that since the silver-aluminum paste used for the first silver-aluminum grid line 50 is relatively active, silver-aluminum spikes will be generated during the sintering process of the silver-aluminum paste to form the first silver-aluminum grid line 50. The silver-aluminum spikes are combined with relatively high activity, making the first silver-aluminum grid line 50 sensitive to water vapor and acid (the acid is generally produced by the hydrolysis of the encapsulation film of the photovoltaic module during the aging process or the acidic material of the film additive in the encapsulation film). Then, during the use of the solar cell, once water vapor or acid contacts the first silver-aluminum grid line 50, the first silver-aluminum grid line 50 is easily corroded, and the contact between the first silver-aluminum grid line 50 and the emitter is destroyed, resulting in poor reliability and stability of the solar cell. At present, there are two main ways to solve the problem of poor component reliability of the existing TOPCon solar cell due to water vapor or acid corrosion. The first method is to select an electrode paste with higher stability. However, the electrode paste with higher stability will cause the efficiency of the solar cell to decrease by 1~2 levels. The second method is to use the silver aluminum paste in combination with the laser sintering auxiliary process. The laser sintering auxiliary process forms induced carriers through a laser beam and combines the bias voltage to form the first silver aluminum grid line 50 with the silver aluminum paste. The structure formed by the laser sintering auxiliary process combined with the bias voltage is as follows: Figure 2 For laser sintering assisted processes, such as Figure 2 As shown, during the sintering process, the induced carriers formed by the laser beam combined with the bias voltage will form a local current on the silver-aluminum paste. The preferred path of the local current is the low-resistance path (since the silver-aluminum paste needs to pass through the front anti-reflection layer 40 and the passivation layer 30 to form an ohmic contact with the emitter 20 located below the passivation layer 30, and in the existing pyramid velvet structure, the passivation layer 30 and the front anti-reflection layer 40 formed at the top of the pyramid are relatively thin, so that the resistance at the top of the pyramid is lower than the resistance of the tower body area, then the induced carriers formed by the laser beam are transmitted along the top of the pyramid, that is, the low-resistance path is from the silver-aluminum paste to the emitter 20. The silver in the silver-aluminum paste is combined with the silicon in the tip of the emitter 20 to form a stable silver-silicon alloy contact site 51 (at the silver-silicon alloy contact site 51, silver and silicon are combined to form a silver-silicon alloy). Although the laser sintering auxiliary process can form a stable silver-aluminum alloy bonding site between the first silver-aluminum grid line 50 and the emitter 20, since the bonding site is relatively single (located at the tip of the pyramid) and uneven, the first silver-aluminum grid line 50 still cannot resist water vapor or acid corrosion, resulting in poor reliability and stability of the solar cell.

[0043] In addition, due to the poor corrosion resistance of silver aluminum grid lines, solar cells using silver aluminum grid lines are currently generally used to make double-glass photovoltaic modules (i.e., the cover and back panels of the photovoltaic modules are both glass). This will greatly reduce the use scenarios of solar cells with silver aluminum grid lines. For example, household or industrial and commercial scenarios that prefer single-glass modules are not suitable for choosing solar cells with silver aluminum grid lines.

[0044] In order to solve the above problems existing in the prior art, an embodiment of the present invention provides a solar cell and a photovoltaic module with a new structure and a preparation method thereof.

[0045] The structure of the solar cell provided by the embodiment of the present invention improves the structure of the metallization area corresponding to the first silver aluminum grid line 50 to increase the number of silver-silicon alloy contact sites 51 formed between the emitter 20 and the first silver aluminum grid line 50, thereby improving the corrosion resistance of the first silver aluminum grid line 50.

[0046] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0047] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0048] in, Figure 3 , Figure 5 , Figure 7 , Fig. 9 and Fig.11 Schematic diagrams showing velvet structures of different structures provided by embodiments of the present invention; Figure 4 , Figure 6 , Figure 8 , Fig.10 and Fig.12 Partial structural schematic diagrams of solar cells with different structures are shown respectively.

[0049] Specifically, Figure 4 , Figure 6 , Figure 8 , Fig.10 and Fig.12 As shown, an embodiment of the present invention provides a solar cell. Figure 4 , Figure 6 , Figure 8 , Fig.10 and Fig.12 As shown, the solar cell may include:

[0050] The first main surface of the silicon substrate 10 is a suede structure;

[0051] An emitter 20, a passivation layer 30 and a front anti-reflection layer 40 are stacked from inside to outside on the first main surface of the silicon substrate 10 and matched with the suede structure, and the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 correspond to the front side of the solar cell;

[0052] and first silver aluminum grid lines 50 spaced apart on the front anti-reflection layer 40, wherein the first silver aluminum grid lines 50 are in 20 ohm contact with the emitter;

[0053] In the suede structure, the metallized area 11 corresponding to the first silver-aluminum grid line 50 and the non-metallized area 12 outside the metallized area 11 meet at least one of the following conditions:

[0054] Condition 1: a first projection coefficient of the metallized region 11 is greater than a second projection coefficient of the non-metallized region 12 outside the metallized region, wherein the first projection coefficient is obtained by dividing the surface area of ​​the metallized region 11 by the projection area of ​​the metallized region 11 on the horizontal plane, and the second projection coefficient is obtained by dividing the surface area of ​​the non-metallized region 12 by the projection area of ​​the non-metallized region 12 on the horizontal plane;

[0055] Condition 2: The roughness of the metallized area 11 is greater than the roughness of the non-metallized area 12;

[0056] Condition 3: the top of the suede area corresponding to the metallized area 11 is a flat structure or a curved structure, and the top of the suede area corresponding to the non-metallized area 12 is a pointed structure;

[0057] Condition 4: the metallized region 11 is a planar structure, and the non-metallized region 12 is a pyramid structure.

[0058] The second main surface of the silicon substrate 10 may be Figure 4 The structure shown is a flat surface, but it can also be a velvet surface. Figure 6 , Figure 8 , Fig.10 and Fig.12 The structure of the front side of the solar cell (i.e., the first main surface of the silicon substrate 10 and the functional layer thereon) is only given as an example, while the structure of the back side of the solar cell (i.e., the second main surface of the silicon substrate 10 and the functional layer thereon) can adopt the existing structure, specifically, Figure 4As shown, a tunneling oxide layer 60, a doped polysilicon layer 70 and a back anti-reflection layer 80 are stacked from inside to outside on the second main surface of the silicon substrate 10, and the tunneling oxide layer 60, the doped polysilicon layer 70 and the back anti-reflection layer 80 correspond to the back of the solar cell; and a second silver aluminum grid line 90 is arranged at intervals on the back anti-reflection layer 80, wherein the second silver aluminum grid line 90 is in ohmic contact with the doped polysilicon layer 70. For the back of the solar cell, the second silver aluminum grid line 90 can be obtained by sintering silver aluminum paste. Through research, it is found that during the sintering process of the silver aluminum paste, only one functional layer (back anti-reflection layer 80) needs to be passed through, so that the silver aluminum paste sintering process can easily reach the doped polysilicon layer 70 and form a stable ohmic contact with the doped polysilicon layer 70.

[0059] Wherein, for condition 1, the first projection coefficient can be calculated by the following calculation formula (1).

[0060] (1)

[0061] in, represents the first projection coefficient; represents the surface area of ​​the metallized region 11; It represents the projection area of ​​the metallized area 11 on the horizontal plane.

[0062] The second projection coefficient can be calculated using the following calculation formula (2).

[0063] (2)

[0064] in, represents the first projection coefficient; represents the surface area of ​​the metallized region 11; It represents the projection area of ​​the non-metallized area 12 on the horizontal plane.

[0065] It is worth noting that the projection area of ​​the metallized region 11 on the horizontal plane and the projection area of ​​the non-metallized region 12 on the horizontal plane refer to the area of ​​the projection area of ​​the metallized region 11 and the non-metallized region 12 on the same horizontal plane. The first projection coefficient represents the surface area of ​​the metallized region 11 corresponding to the unit projection area on a horizontal plane, and the second projection coefficient represents the surface area of ​​the non-metallized region 12 corresponding to the unit projection area on a horizontal plane. The first projection coefficient of the metallized region 11 is greater than the second projection coefficient of the non-metallized region 12 outside the metallized region, indicating that for the same projection area, the surface area of ​​the metallized region 11 is greater than the surface area of ​​the non-metallized region 12.

[0066] With respect to the above conditions 1 to 4, the metallized region 11 and the non-metallized region 12 in the velvet structure on the first main surface of the silicon substrate 10 may satisfy conditions 1 to 3 at the same time, or may satisfy conditions 1, 2 and 4 at the same time, or may satisfy only one of the above conditions 1 to 4. It can be understood that conditions 3 and 4 will not exist at the same time, that is, the metallized region 11 and the non-metallized region 12 in the velvet structure on the first main surface of the silicon substrate 10 will not satisfy condition 4 when condition 3 is satisfied; the metallized region 11 and the non-metallized region 12 in the velvet structure on the first main surface of the silicon substrate 10 will not satisfy condition 3 when condition 4 is satisfied.

[0067] It is worth noting that the first silver-aluminum grid line 50 of the embodiment of the present invention can be formed by conventional silver-aluminum paste, or by low-aluminum silver-aluminum paste or aluminum-free silver paste.

[0068] With respect to the solar cell provided in the embodiment, in the velvet structure corresponding to the front side of the solar cell, the metallized region 11 corresponding to the first silver aluminum grid line 50 and the non-metallized region 12 outside the metallized region 11 meet at least one of the following conditions: Condition 1, the first projection coefficient of the metallized region 11 is greater than the second projection coefficient of the non-metallized region 12 outside the metallized region 11; Condition 2, the roughness of the metallized region 11 is greater than the roughness of the non-metallized region 12; Condition 3, the top of the velvet region corresponding to the metallized region 11 is a planar structure or a curved structure, and the top of the velvet region corresponding to the non-metallized region 12 is a pointed structure; Condition 4, the metallized region 11 is a planar structure, and the non-metallized region 12 is a pyramid structure; even if the first silver-aluminum grid line 50 needs to pass through the passivation layer 30 and the front anti-reflection layer 40, the metallized area 11 can effectively increase the silver-silicon alloy contact sites 51 formed by the silver in the first silver-aluminum grid line 50 and the silicon in the emitter 20. The increase of the silver-silicon alloy contact sites 51 can improve the corrosion resistance of the first silver-aluminum grid line. In addition, even if corrosion holes appear in the first silver-aluminum grid line 50 in the area outside the silver-silicon alloy contact sites 51, due to the large number of silver-silicon alloy contact sites 51, the first silver-aluminum grid line 50 can still maintain good conductivity, thereby ensuring the current transmission of the first silver-aluminum grid line 50 and improving the corrosion resistance of the first silver-aluminum grid line 50, thereby improving the reliability of the solar cell.

[0069] Furthermore, the solar cell provided by the embodiment of the present invention has a front structure (the velvet structure designed in the embodiment of the present invention is coordinated with the emitter 20, the passivation layer 30, the front anti-reflection layer 40 and the first silver-aluminum grid line 50) and a back structure (coordinated tunneling oxide layer 60, doped polysilicon layer 70, back anti-reflection layer 80 and second silver-aluminum grid line 90). After being corroded by water vapor or acid, the solar cell still has a relatively good photoelectric conversion efficiency. Therefore, the solar cell provided by the embodiment of the present invention can effectively improve the stability and reliability of the solar cell.

[0070] It can be understood that the front and back of a solar cell are opposite to each other. Specifically, the front of a solar cell generally refers to the solar cell encapsulated into a photovoltaic module or the cell slices cut from the solar cell encapsulated into a photovoltaic module. During the use of the photovoltaic module, the main surface of the solar cell or the cell slices cut from the solar cell facing upward is the front of the solar cell, and the main surface of the solar cell or the cell slices cut from the solar cell facing downward is the back of the solar cell.

[0071] It is worth noting that the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 match the velvet structure, which generally means that the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 are grown or deposited along the morphology of the velvet structure. At the concave position of the velvet structure, the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 are also concave, and at the convex position of the velvet structure, the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 are also convex accordingly. Based on this, the structure provided by the embodiment of the present invention can effectively increase the number of silver-silicon alloy contact sites 51 formed between the first silver-aluminum grid line 50 and the emitter 20 by designing the velvet structure corresponding to the non-metallized area and the metallized area of ​​the silicon substrate 10. Since the silver-silicon alloy contact site 51 can resist water vapor and acid corrosion, the increase in the number of the silver-silicon alloy contact site 51 effectively improves the water vapor corrosion resistance and acid corrosion resistance of the first silver-aluminum grid line 50, thereby improving the reliability and stability of the solar cell.

[0072] The metallized area 11 can be formed by laser or chemical etching. That is, by using the existing laser or chemical etching, the metallized area 11 and the non-metallized area 12 with different textures can be obtained, without adding new processing means, and can be completed in the existing solar cell processing process, so as to effectively control the production cost of solar cells.

[0073] Generally speaking, if Fig.11As shown, the base width D1 of the pyramid corresponding to the velvet area of ​​the non-metallized area 12 is 1 μm to 10 μm. For example, the base width of the pyramid corresponding to the velvet area of ​​the non-metallized area 12 can be 1 μm, 3 μm, 5 μm, 6 μm, 8 μm or 10 μm, etc. Further, as Fig.11 As shown, the height H1 of the pyramid corresponding to the velvet area of ​​the non-metallized area 12 is 1 μm to 10 μm. For example, the height of the pyramid corresponding to the velvet area of ​​the non-metallized area 12 can be 1 μm, 2 μm, 4 μm, 5 μm, 6 μm, 8 μm or 10 μm, etc. By controlling the bottom width and height of the pyramid of the velvet area of ​​the non-metallized area 12, the light trapping property of the non-metallized area 12 can be effectively improved to improve the light utilization rate of the solar cell.

[0074] There may be various structures that satisfy at least one of the above four conditions.

[0075] Specifically, the first structure that satisfies at least one of the above four conditions can be as follows: Figure 3 and Figure 4 As shown, the metallized area 11 of the velvet structure is arranged with a convex structure. The convex structure can be formed by laser processing the metallized area 11 or chemically etching (texturing liquid with additives) the metallized area 11 after preparing the same velvet structure on the entire surface of the first main surface of the silicon substrate 10. Among them, the laser processing parameters or the concentration parameters of the texturing liquid and the texturing liquid processing parameters can be adjusted according to experiments. For the velvet structure of the first structure, as shown in FIG. Figure 4 As shown, in the metallization region 11, the silver of the first silver-aluminum grid line 50 is combined with the silicon in the emitter 20 between each two adjacent protrusion structures to form a silver-silicon alloy contact site 51. The protrusion structures arranged in the metallization region 11 can effectively increase the number of the silver-silicon alloy contact sites 51. Even if water vapor or acid corrosion occurs in the area outside the silver-silicon alloy contact sites 51 in the first silver-aluminum grid line 50, the first silver-aluminum grid line 50 can still maintain connectivity and good conductivity due to the large number of silver-silicon alloy contact sites 51. In addition, the silver-silicon alloy can resist water vapor or acid corrosion, and the large number of silver-silicon alloy contact sites 51 can also effectively improve the corrosion resistance of the first silver-aluminum grid line 50.

[0076] Furthermore, the second structure that satisfies at least one of the above four conditions can be as follows: Figure 5 and Figure 6As shown, the top of the velvet area corresponding to the metallized area 11 is a plane structure. On the plane structure at the top of the velvet area, on the cross section of the plane structure, a plurality of silver-silicon alloy contact sites 51 are arranged, and the silver-silicon alloy contact sites 51 are formed by combining the silver of the first silver-aluminum grid line 50 with the silicon in the emitter 20, and the cross sections of the plurality of plane structures are perpendicular to the extension direction of the first silver-aluminum grid line 50. The design of the plane structure makes the thickness of the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 laid on the plane structure relatively uniform, so that during the ohmic contact process between the first silver-aluminum grid line 50 and the emitter 20, the emitter 20 part on the plane structure can be in relatively balanced contact with the first silver-aluminum grid line 50, so that a uniformly distributed and large number of silver-silicon alloy contact sites 51 are formed on the emitter 20 on the plane structure, and the water vapor corrosion resistance and acid corrosion resistance of the first silver-aluminum grid line 50 are improved.

[0077] The top of the velvet area corresponding to the metallized area 11 is a planar structure, such as Figure 5 As shown, the width D3 of the planar structure is generally 0.5 μm to 3 μm. For example, the width D3 of the planar structure may be 0.5 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, 2.8 μm or 3 μm, etc. By controlling the width of the planar structure, it is possible to ensure that enough silver-silicon alloy contact sites 51 are formed on the planar structure, so that the first silver-aluminum grid line 50 can achieve the effect of resisting water vapor corrosion and acid corrosion.

[0078] Further, a third structure that satisfies at least one of the above four conditions can be as follows Figure 7 and Figure 8 As shown, the velvet area corresponding to the metallized area 11 is a plane structure. On the cross section of the plane structure, a plurality of silver-silicon alloy contact sites 51 are arranged, and the silver-silicon alloy contact sites 51 are formed by combining the silver of the first silver-aluminum grid line 50 with the silicon in the emitter 20. The cross sections of the plurality of plane structures are perpendicular to the extension direction of the first silver-aluminum grid line 50. As described above, the design of the plane structure makes the thickness of the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 laid on the plane structure relatively uniform. Therefore, during the ohmic contact between the first silver-aluminum grid line 50 and the emitter 20, the emitter 20 part on the plane structure can be relatively evenly contacted with the first silver-aluminum grid line 50, thereby forming a uniformly distributed and large number of silver-silicon alloy contact sites 51 on the emitter 20 on the plane structure, thereby improving the water vapor corrosion resistance and acid corrosion resistance of the first silver-aluminum grid line 50.

[0079] Further, a fourth structure that satisfies at least one of the above four conditions can be as follows Fig. 9 and Fig.10As shown, the top of the velvet area corresponding to the metallized area 11 is a curved surface structure, and a plurality of silver-silicon alloy contact sites 51 are arranged on the cross section of the curved surface structure. The silver-silicon alloy contact sites 51 are formed by combining the silver of the first silver-aluminum grid line 50 with the silicon in the emitter 20. The cross sections of the plurality of curved surface structures are perpendicular to the extension direction of the first silver-aluminum grid line 50. It is worth noting that the curved surface structure is generally a convex arc. Through the design of the curved surface structure, the thickness of the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 laid on the curved surface structure can also be made relatively uniform. Therefore, during the ohmic contact between the first silver-aluminum grid line 50 and the emitter 20, the emitter 20 part on the curved surface structure can be relatively evenly contacted with the first silver-aluminum grid line 50, thereby forming a uniformly distributed and large number of silver-silicon alloy contact sites 51 on the emitter 20 on the curved surface structure, thereby improving the water vapor corrosion resistance and acid corrosion resistance of the first silver-aluminum grid line 50.

[0080] In addition, a fifth structure that satisfies at least one of the above four conditions can be as follows Fig.11 and Fig.12 As shown, the velvet area corresponding to the metallized area 11 is a pyramid structure, and the size of the pyramid structure of the velvet area corresponding to the metallized area 11 is smaller than the pyramid structure of the velvet area corresponding to the non-metallized area 12. Specifically, as Fig.11 As shown, the width D2 of the bottom of the pyramid structure corresponding to the velvet area of ​​the metallized area 11 is 1 μm to 3 μm. For example, the width of the bottom of the pyramid structure corresponding to the velvet area of ​​the metallized area 11 can be 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm. Fig.11 As shown, the height H2 of the pyramid structure corresponding to the velvet area of ​​the metallized area 11 is 0.5 μm to 3 μm. For example, the height H2 of the pyramid structure corresponding to the velvet area of ​​the metallized area 11 can be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm, etc. Through this structural design, the metallized area 11 has a tighter pyramid. Although the first silver aluminum grid line 50 and the pyramid-shaped emitter 20 can only form a relatively small number of silver-silicon alloy contact sites 51 at the top of the tower, since the metallized area 11 has a smaller pyramid, it can make the metallized area 11 have tighter and more pyramids, so that the metallized area 11 forms more silver-silicon alloy contact sites 51, and improves the water vapor corrosion resistance and acid rain corrosion resistance of the first silver aluminum grid line 50.

[0081] For the fifth structure described above, the pyramid structure of the velvet area corresponding to the metallized area 11 is prepared before the pyramid structure of the velvet area corresponding to the non-metallized area 12. Specifically, the first main surface of the silicon substrate 10 is first etched by a texturing liquid with an additive to form a pyramid velvet structure of smaller size (the width of the pyramid is 1μm~3μm, and the height is 1μm~3μm), and then the metallized area 11 is covered with a mask or a protective film, and the non-metallized area 12 is further treated with a texturing liquid with an additive, so that the pyramid of the velvet structure of the non-metallized area 12 is further enlarged to meet the requirement of improving the light trapping property of the non-metallized area 12.

[0082] It is worth noting that the texturing liquid with additives can be directly selected from existing texturing liquids, and the parameters related to the texturing liquid treatment of the surface of the silicon substrate 10, such as treatment time, treatment temperature, etc., can be controlled through experiments.

[0083] In addition, the silver-silicon alloy contact sites 51 formed in the solar cells of the above-mentioned structures are formed by pre-sintering and curing the silver-aluminum paste after the silver-aluminum paste is coated on the front anti-reflection layer 40, and then the cured silver-aluminum paste is directed by a laser beam to form local induced carriers, and a bias voltage is introduced to the solar cell to form a local current, which causes the silver in the cured silver-aluminum paste to combine with the silicon in the emitter 20 on the metallization regions of the above-mentioned first structure, second structure, third structure, fourth structure and fifth structure to form the silver-silicon alloy contact sites 51. Since the metallization regions of the above-mentioned first structure and fifth structure can provide more low-resistance paths, and the second structure, third structure and fourth structure can provide a relatively large-sized uniform thickness region (the thickness of the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 in the uniform thickness region is uniform), the cured silver-aluminum paste can form a large-sized contact with the emitter 20 in the relatively large-sized uniform thickness region, which helps to increase the number of the formed silver-silicon alloy contact sites 51.

[0084] It is worth noting that the solar cell provided in the embodiment of the present invention may be a TOPCon cell. However, the structure of the solar cell provided in the embodiment of the present invention is not limited to a TOPCon cell.

[0085] Furthermore, the embodiments of the present invention are respectively Figure 2 The existing structure solar cell shown in FIG. Figure 6 The solar cell of the second structure provided by the embodiment of the present invention is shown as follows Fig.12The solar cell with the fifth structure provided in the embodiment of the present invention was subjected to an acetic acid immersion experiment. The results showed that after acid corrosion, the power loss of the solar cell with the existing structure exceeded 30%, the power loss of the solar cell with the second structure provided in the embodiment of the present invention was 8.12%, and the power loss of the solar cell with the fifth structure provided in the embodiment of the present invention was 3.55%, indicating that the structure provided in the embodiment of the present invention can effectively improve the acid corrosion resistance of the solar cell.

[0086] The solar cell with the second structure provided by the embodiment of the present invention and the solar cell with the fifth structure provided by the embodiment of the present invention were further subjected to damp heat test experiments, and the results showed that after the damp heat test, the power loss of the solar cell with the second structure was 3.47%, and the power loss of the solar cell with the fifth structure was 2.51%, both of which met the standard of IEC 61215. This shows that the structure of the solar cell provided by the embodiment of the present invention can effectively improve the corrosion resistance, reliability and stability of the solar cell, and is helpful to improve the corrosion resistance, reliability and stability of the single-glass photovoltaic module with the solar cell.

[0087] Furthermore, an embodiment of the present invention further provides a photovoltaic module, which may include: a solar cell provided by any of the above embodiments or a cell slice cut from a solar cell provided by any of the above embodiments.

[0088] The photovoltaic module can be a single-glass photovoltaic module or a double-glass photovoltaic module, which improves the application scenarios of photovoltaic modules, and the solar cell can ensure that the single-glass photovoltaic module is resistant to water vapor corrosion and acid corrosion, thereby improving the stability and reliability of the single-glass photovoltaic module.

[0089] Furthermore, an embodiment of the present invention also provides a method for preparing a solar cell. Fig.13 As shown, the method for preparing the solar cell may include the following steps:

[0090] Step S1301 : preparing a velvet structure on the first main surface of the silicon substrate 10 , wherein the velvet structure has metallized regions 11 and non-metallized regions 12 arranged alternately.

[0091] In the suede structure, the metallized area 11 and the non-metallized area 12 meet at least one of the following conditions:

[0092] Condition 1: a first projection coefficient of the metallized region 11 is greater than a second projection coefficient of the non-metallized region 12 outside the metallized region 11, wherein the first projection coefficient is obtained by dividing the surface area of ​​the metallized region 11 by the projection area of ​​the metallized region 11 on the horizontal plane, and the second projection coefficient is obtained by dividing the surface area of ​​the non-metallized region 12 by the projection area of ​​the non-metallized region 12 on the horizontal plane;

[0093] Condition 2: The roughness of the metallized area 11 is greater than the roughness of the non-metallized area 12;

[0094] Condition 3: the top of the suede area corresponding to the metallized area 11 is a flat structure or a curved structure, and the top of the suede area corresponding to the non-metallized area 12 is a pointed structure;

[0095] Condition 4: the metallized region 11 is a planar structure, and the non-metallized region 12 is a pyramid structure.

[0096] Step S1302: An emitter 20, a passivation layer 30 and a front anti-reflection layer 40 matching the suede structure are sequentially stacked on the first main surface of the silicon substrate 10, wherein the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 correspond to the front side of the solar cell.

[0097] The above-mentioned velvet structure can be directly obtained by using the existing velvet-making liquid and adjusting the velvet-making parameters of the velvet-making liquid for treating the metallized area 11 and the non-metallized area 12 .

[0098] Step S1303: silver-aluminum paste is disposed on the front anti-reflection layer 40 corresponding to the metallized area, and pre-sintered, and the first silver-aluminum grid line 50 is formed by laser excitation of local carriers combined with bias voltage, and the first silver-aluminum grid line 50 is in 20 ohm contact with the emitter.

[0099] The method for preparing a solar cell provided in an embodiment of the present invention forms a differentiated structure in the metallized area and the non-metallized area through step S1301, and increases the number of silver-silicon alloy bonding sites 51 formed by the first silver-aluminum grid line 50 and the emitter 20, so as to improve the corrosion resistance of the solar cell to water vapor and acid, thereby improving the reliability and stability of the solar cell.

[0100] In summary, the embodiments of the present invention provide the following technical solutions:

[0101] Technical solution 1, a solar cell, comprising:

[0102] The first main surface of the silicon substrate 10 is a suede structure;

[0103] An emitter 20, a passivation layer 30 and a front anti-reflection layer 40 are stacked from inside to outside on the first main surface of the silicon substrate 10 and matched with the velvet structure, and the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 correspond to the front side of the solar cell;

[0104] and first silver-aluminum grid lines 50 spaced apart on the front anti-reflection layer 40 , wherein the first silver-aluminum grid lines 50 are in ohmic contact with the emitter 20 ;

[0105] In the suede structure, the metallized area 11 corresponding to the first silver-aluminum grid line 50 and the non-metallized area 12 outside the metallized area 11 meet at least one of the following conditions:

[0106] Condition 1: A first projection coefficient of the metallized region 11 is greater than a second projection coefficient of a non-metallized region 12 outside the metallized region, wherein the first projection coefficient is obtained by dividing the surface area of ​​the metallized region 11 by the projection area of ​​the metallized region 11 on a horizontal plane, and the second projection coefficient is obtained by dividing the surface area of ​​the non-metallized region 12 by the projection area of ​​the non-metallized region 12 on a horizontal plane;

[0107] Condition 2: The roughness of the metallized area 11 is greater than the roughness of the non-metallized area 12;

[0108] Condition 3: the top of the suede area corresponding to the metallized area 11 is a flat structure or a curved structure, and the top of the suede area corresponding to the non-metallized area 12 is a pointed structure;

[0109] Condition 4: the metallized region 11 is a planar structure, and the non-metallized region 12 is a pyramid structure.

[0110] Technical solution 2: The solar cell according to technical solution 1,

[0111] The metallized area 11 is arranged with protruding structures.

[0112] Technical solution 3: The solar cell according to technical solution 1 or 2,

[0113] The velvet area corresponding to the metallized area 11 is a pyramid structure, and the size of the pyramid structure of the velvet area corresponding to the metallized area 11 is smaller than the pyramid structure of the velvet area corresponding to the non-metallized area 12 .

[0114] Technical solution 4: The solar cell according to technical solution 3,

[0115] The width of the bottom of the pyramid structure corresponding to the velvet area of ​​the metallized area 11 is 1 μm to 3 μm;

[0116] and / or,

[0117] The height of the pyramid structure corresponding to the textured area of ​​the metallized area 11 is 0.5 μm to 3 μm.

[0118] Technical solution 5. The solar cell according to technical solution 2,

[0119] In the metallization region 11 , between every two adjacent protruding structures, the silver of the first silver-aluminum gate line 50 is combined with the silicon in the emitter 20 to form a silver-silicon alloy contact site 51 .

[0120] Technical solution 6. The solar cell according to technical solution 1,

[0121] The top of the velvet area corresponding to the metallized area 11 is a planar structure or the metallized area 11 is a planar structure, and a plurality of silver-silicon alloy contact sites 51 are arranged on the cross section of the planar structure, and the silver-silicon alloy contact sites 51 are formed by combining the silver of the first silver-aluminum grid line 50 with the silicon in the emitter 20, and the cross sections of the plurality of planar structures are perpendicular to the extension direction of the first silver-aluminum grid line 50;

[0122] or,

[0123] The top of the velvet area corresponding to the metallized area 11 is a curved surface structure. On the cross section of the curved surface structure, a plurality of silver-silicon alloy contact sites 51 are arranged. The silver-silicon alloy contact sites 51 are formed by combining the silver of the first silver-aluminum gate line 50 with the silicon in the emitter 20. The cross sections of the plurality of curved surface structures are perpendicular to the extension direction of the first silver-aluminum gate line 50.

[0124] Technical solution 7. The solar cell according to technical solution 1,

[0125] The metallized area 11 is formed by laser or chemical etching;

[0126] and / or,

[0127] The base width of the pyramid corresponding to the velvet area of ​​the non-metallized area 12 is 1 μm to 10 μm;

[0128] and / or,

[0129] The height of the pyramids in the velvet area corresponding to the non-metallized area 12 is 1 μm to 10 μm.

[0130] Technical solution 8. The solar cell according to technical solution 3,

[0131] The pyramid structure of the velvet area corresponding to the metallized area 11 is prepared before the pyramid structure of the velvet area corresponding to the non-metallized area 12 .

[0132] Technical solution 9. The solar cell according to any one of technical solutions 1, 2, and 4 to 8, further comprising:

[0133] A tunneling oxide layer 60, a doped polysilicon layer 70 and a back anti-reflection layer 80 are stacked from inside to outside on the second main surface of the silicon substrate 10, wherein the tunneling oxide layer 60, the doped polysilicon layer 70 and the back anti-reflection layer 80 correspond to the back side of the solar cell;

[0134] And second silver aluminum grid lines 90 are spaced apart and arranged on the back anti-reflection layer 80 , wherein the first silver aluminum grid lines 50 are in ohmic contact with the doped polysilicon layer 70 .

[0135] Technical solution 10, a photovoltaic module, comprising:

[0136] A solar cell as described in any one of Technical Solutions 1 to 9 or a cell slice cut from a solar cell as described in any one of Technical Solutions 1 to 9.

[0137] Technical solution 11, the method for preparing a solar cell according to any one of technical solutions 1 to 9, comprising:

[0138] Step 1: preparing a velvet structure on the first main surface of the silicon substrate 10, wherein the velvet structure has metallized regions 11 and non-metallized regions 12 arranged alternately;

[0139] Step 2, sequentially stacking an emitter 20, a passivation layer 30 and a front anti-reflection layer 40 matching the suede structure on the first main surface of the silicon substrate 10, wherein the emitter 20, the passivation layer 30 and the front anti-reflection layer 40 correspond to the front side of the solar cell;

[0140] Step 3, disposing silver-aluminum paste on the front anti-reflection layer 40 corresponding to the metallized area, and forming a first silver-aluminum grid line 50 by laser-assisted sintering combined with a bias voltage, wherein the first silver-aluminum grid line 50 is in 20-ohm contact with the emitter;

[0141] In the suede structure, the metallized area 11 and the non-metallized area 12 meet at least one of the following conditions:

[0142] Condition 1: A first projection coefficient of the metallized region 11 is greater than a second projection coefficient of a non-metallized region 12 outside the metallized region 11, wherein the first projection coefficient is obtained by dividing the surface area of ​​the metallized region 11 by the projection area of ​​the metallized region 11 on a horizontal plane, and the second projection coefficient is obtained by dividing the surface area of ​​the non-metallized region 12 by the projection area of ​​the non-metallized region 12 on a horizontal plane;

[0143] Condition 2: The roughness of the metallized area 11 is greater than the roughness of the non-metallized area 12;

[0144] Condition 3: the top of the suede area corresponding to the metallized area 11 is a flat structure or a curved structure, and the top of the suede area corresponding to the non-metallized area 12 is a pointed structure;

[0145] Condition 4: the metallized region 11 is a planar structure, and the non-metallized region 12 is a pyramid structure.

[0146] The introduction provided in the above steps is only used to help understand the method, structure and core idea of ​​the present invention. For ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also belong to the scope of protection of the claims of the present invention.

Claims

1. A solar cell, characterized in that: include: A silicon substrate (10) having a velvet structure on its first main surface; An emitter (20), a passivation layer (30) and a front anti-reflection layer (40) are stacked from inside to outside on the first main surface of the silicon substrate (10) and matched with the velvet structure, wherein the emitter (20), the passivation layer (30) and the front anti-reflection layer (40) correspond to the front side of the solar cell; and first silver-aluminum grid lines (50) arranged at intervals on the front anti-reflection layer (40), wherein the first silver-aluminum grid lines (50) are in ohmic contact with the emitter (20); In the velvet structure, the metallized area (11) corresponding to the first silver-aluminum grid line (50) and the non-metallized area (12) outside the metallized area (11) meet at least one of the following conditions: Condition 1: A first projection coefficient of the metallized region (11) is greater than a second projection coefficient of a non-metallized region (12) outside the metallized region, wherein the first projection coefficient is obtained by dividing the surface area of ​​the metallized region (11) by the projection area of ​​the metallized region (11) on a horizontal plane, and the second projection coefficient is obtained by dividing the surface area of ​​the non-metallized region (12) by the projection area of ​​the non-metallized region (12) on a horizontal plane; Condition 2: The roughness of the metallized area (11) is greater than the roughness of the non-metallized area (12); Condition 3: the top of the velvet area corresponding to the metallized area (11) is a flat structure or a curved structure, and the top of the velvet area corresponding to the non-metallized area (12) is a pointed structure; Condition 4: the metallized region (11) is a planar structure, and the non-metallized region (12) is a pyramid structure.

2. The solar cell according to claim 1, characterized in that The metallized area (11) is arranged with protruding structures.

3. The solar cell according to claim 1 or 2, characterized in that: The velvet area corresponding to the metallized area (11) is a pyramid structure, and the size of the pyramid structure of the velvet area corresponding to the metallized area (11) is smaller than the pyramid structure of the velvet area corresponding to the non-metallized area (12).

4. The solar cell according to claim 3, characterized in that: The width of the base of the pyramid structure of the velvet area corresponding to the metallized area (11) is 1 μm to 3 μm; and / or, The height of the pyramid structure of the velvet area corresponding to the metallized area (11) is 0.5 μm to 3 μm.

5. The solar cell according to claim 2, characterized in that: In the metallized region (11), between each two adjacent protruding structures, the silver of the first silver-aluminum grid line (50) combines with the silicon in the emitter (20) to form a silver-silicon alloy contact site (51).

6. The solar cell according to claim 1, characterized in that The top of the velvet area corresponding to the metallized area (11) is a planar structure or the metallized area (11) is a planar structure, and a plurality of silver-silicon alloy contact sites (51) are arranged on a cross section of the planar structure, wherein the silver-silicon alloy contact sites (51) are formed by combining the silver of the first silver-aluminum grid line (50) with the silicon in the emitter (20), and the cross sections of the plurality of planar structures are perpendicular to the extension direction of the first silver-aluminum grid line (50); or, The top of the velvet area corresponding to the metallized area (11) is a curved surface structure, and a plurality of silver-silicon alloy contact sites (51) are arranged on the cross section of the curved surface structure, wherein the silver-silicon alloy contact sites (51) are formed by combining the silver of the first silver-aluminum grid line (50) with the silicon in the emitter (20), and the cross sections of the plurality of curved surface structures are perpendicular to the extension direction of the first silver-aluminum grid line (50).

7. The solar cell according to claim 1, characterized in that The metallized area (11) is formed by laser or chemical etching; and / or, The base width of the pyramid of the velvet area corresponding to the non-metallized area (12) is 1 μm to 10 μm; and / or, The height of the pyramids in the velvet area corresponding to the non-metallized area (12) is 1 μm to 10 μm.

8. The solar cell according to claim 3, characterized in that: The pyramid structure of the velvet area corresponding to the metallized area (11) is prepared before the pyramid structure of the velvet area corresponding to the non-metallized area (12).

9. A photovoltaic module, characterized in that: include: A solar cell as claimed in any one of claims 1 to 8 or a cell slice cut from a solar cell as claimed in any one of claims 1 to 9.

10. The method for preparing a solar cell according to any one of claims 1 to 8, characterized in that: include: Step 1: preparing a velvet structure on a first main surface of a silicon substrate (10), wherein the velvet structure has metallized regions (11) and non-metallized regions (12) arranged alternately; Step 2, sequentially stacking an emitter (20), a passivation layer (30) and a front anti-reflection layer (40) matching the velvet structure on the first main surface of the silicon substrate (10), wherein the emitter (20), the passivation layer (30) and the front anti-reflection layer (40) correspond to the front side of the solar cell; Step 3, placing silver-aluminum paste on the front anti-reflection layer (40) corresponding to the metallized area, and pre-sintering, and forming a first silver-aluminum grid line (50) by laser excitation of local carriers combined with a bias voltage, wherein the first silver-aluminum grid line (50) is in ohmic contact with the emitter (20); In the velvet structure, the metallized area (11) and the non-metallized area (12) satisfy at least one of the following conditions: Condition 1: The first projection coefficient of the metallized area (11) is greater than the second projection coefficient of the non-metallized area (12) outside the metallized area (11), wherein the first projection coefficient is obtained by dividing the surface area of ​​the metallized area (11) by the projection area of ​​the metallized area (11) on the horizontal plane, and the second projection coefficient is obtained by dividing the surface area of ​​the non-metallized area (12) by the projection area of ​​the non-metallized area (12) on the horizontal plane; Condition 2: The roughness of the metallized area (11) is greater than the roughness of the non-metallized area (12); Condition 3: the top of the velvet area corresponding to the metallized area (11) is a flat structure or a curved structure, and the top of the velvet area corresponding to the non-metallized area (12) is a pointed structure; Condition 4: the metallized region (11) is a planar structure, and the non-metallized region (12) is a pyramid structure.

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