Solar cell and photovoltaic module

Abstract

The invention provides a solar cell and a photovoltaic module, and relates to the technical field of photovoltaics. The solar cell includes: a silicon substrate; the silicon substrate is provided with a first surface and a second surface which are opposite to each other in the direction of the thickness of the silicon substrate; a texture structure is arranged on the first surface; the transmission layer and the passivation anti-reflection layer are stacked on the texture structure; in the direction of the thickness of the silicon substrate, the transmission layer is located between the silicon substrate and the passivation anti-reflection layer; the passivation anti-reflection layer is provided with a plurality of openings; the ratio of the maximum size of the opening to the one-dimensional size of the texture structure is 0.5 to 5. According to the invention, the quality of the transmission layer, the passivation anti-reflection layer and other film layers below and around the opening is good, and good passivation and other effects can be realized; meanwhile, the binding force between the electrode and the transmission layer is large, the binding force or the contact effect between the electrode and the transmission layer is improved, the current collection and conduction effects are improved, and the performance of the solar cell is further improved.

Description

Technical Field

[0001] The invention relates to the field of photovoltaic technology, in particular to a solar cell and a photovoltaic module. Background Art

[0002] Solar cells are devices that directly convert light energy into electrical energy through the photoelectric effect. Since solar cells are mainly used for clean energy, they have broad application prospects. Specifically, solar cells use the photovoltaic principle to generate carriers, and then use electrodes to lead out the carriers, thereby facilitating the effective use of electrical energy.

[0003] The traditional high-temperature metallization process uses high-temperature silver paste to sinter at high temperature on the passivation anti-reflection layer. The paste can penetrate the interface of the passivation anti-reflection layer and form a good metal contact with the underlying transmission layer. However, due to the high cost of high-temperature silver paste, the industry has been actively conducting research on other metallization processes in recent years. For example, an opening is made in the passivation anti-reflection layer to expose the underlying transmission layer, and a low-temperature metallization process is used to make electrodes on the exposed transmission layer, such as using low-temperature paste instead of high-temperature silver paste, or using an electroplating process to form electrodes. At the opening, the bonding force or contact effect between the electrode and the transmission layer has a great influence on the current collection and conduction effect.

[0004] In existing solar cells, there is a contradiction between the bonding force or contact effect between the electrode and the transmission layer, and the quality of the film layer, which affects the performance of the solar cell. Summary of the invention

[0005] The present invention provides a solar cell and a photovoltaic module, aiming to solve the problem that in existing solar cells, there is a contradiction between the bonding force or contact effect between an electrode and a transmission layer and the quality of a film layer.

[0006] A first aspect of the present invention provides a solar cell, comprising:

[0007] A silicon substrate; in the direction of the thickness of the silicon substrate, the silicon substrate has a first surface and a second surface opposite to each other;

[0008] A texture structure is arranged on the first surface; a transmission layer and a passivation anti-reflection layer are stacked on the texture structure; in the direction where the thickness of the silicon substrate is located, the transmission layer is located between the silicon substrate and the passivation anti-reflection layer; the passivation anti-reflection layer has a plurality of openings; and the ratio of the maximum size of the opening to the one-dimensional size of the texture structure is 0.5 to 5.

[0009] In the present application, the passivation anti-reflection layer usually causes damage to the film layer below and around the opening during the opening process. The texture structure on the first surface shows regular concave-convex changes, and the film layer on the raised ridges is more easily damaged. When the ratio of the maximum size of the opening to the one-dimensional size of the texture structure is greater than 5, the opening is too large, and the opening area covers too many texture structures. The opening process causes great damage to the film layer below and around the opening, affecting the quality of the film layer, especially the passivation quality. When the ratio of the maximum size of the opening to the one-dimensional size of the texture structure is less than 0.5, the opening is too small. When an electrode is arranged above the opening, not only is the contact area between the electrode and the transmission layer exposed at the opening too small, affecting the collection and conduction effect of current or carriers, but also, the texture structure has a larger specific surface area and its raised ridges are rougher. If the opening is too small, the opening area covers too few texture structures, which also makes the roughness of the opening The roughness is too small, resulting in poor bonding or contact between the electrode and the transmission layer; in the present application, the ratio of the maximum size of the opening to the one-dimensional size of the texture structure is 0.5 to 5, at least, the damage to the film layer below and around the opening during the opening process, as well as the bonding and contact performance balance between the electrode and the transmission layer, the transmission layer below and around the opening, the passivation anti-reflection layer and other film layers are of good quality, and good passivation effects can be achieved; at the same time, the bonding between the electrode and the transmission layer is large, which prevents subsequent processes from pulling off, has strong reliability, and improves the bonding or contact effect between the electrode and the transmission layer, while reducing contact resistance, improving current collection and conduction effects, and thus improving the performance of solar cells. In summary, the present application achieves both good passivation effects and good contact performance.

[0010] Optionally, the transmission layer includes: a first transmission layer and a second transmission layer, and the first transmission layer and the second transmission layer have different doping types;

[0011] The maximum size of the opening in the corresponding area of ​​the first transmission layer is 1 to 5 times the one-dimensional size of the texture structure;

[0012] The maximum size of the opening in the corresponding area of ​​the second transmission layer is 0.5 to 5 times the one-dimensional size of the texture structure.

[0013] Optionally, the transmission layer includes a plurality of transmission areas, and in one of the transmission areas, the openings are arranged at intervals to form at least one opening row.

[0014] Optionally, in one of the transmission areas, the number of the rows of openings is greater than or equal to 2; and the spacing between adjacent rows of openings is 0.5 to 5 times the one-dimensional size of the texture structure.

[0015] Optionally, the openings in adjacent rows of openings are staggered.

[0016] Optionally, within one row of openings, a spacing between adjacent openings is 1 to 7 times a one-dimensional dimension of the texture structure.

[0017] Optionally, the texture structure includes: a tower base; a one-dimensional size of the tower base is 5um to 40um.

[0018] Optionally, in a side of the transmission layer facing away from the silicon substrate, an area corresponding to the opening is a contact area; and at least one hole is provided at an edge line of the tower base in the contact area.

[0019] Optionally, the tower bases are arranged in a row along the extension direction of the transmission zone; and / or the openings are spaced apart and arranged in a row along the extension direction of the transmission zone.

[0020] Optionally, at least some of the holes at the ridges of the tower base in the contact area are interconnected.

[0021] Optionally, within one row of openings, the spacing between adjacent openings is 10 μm to 100 μm; and / or the spacing between adjacent rows of openings is 8 μm to 80 μm.

[0022] Optionally, the transmission layer includes: a first transmission layer and a second transmission layer, the first transmission layer and the second transmission layer have different doping types; the side length of the tower base in the second transmission layer is greater than the side length of the tower base in the first transmission layer; and / or the depth of the tower base in the second transmission layer is less than the depth of the tower base in the first transmission layer.

[0023] Optionally, the maximum size of the opening is 10 μm to 45 μm.

[0024] Optionally, it further includes an electrode, which is arranged on a side of the passivation anti-reflection layer away from the silicon substrate, and the electrode contacts the transmission layer through the opening; the electrode includes a stacked seed layer and a non-burn-through slurry layer.

[0025] A second aspect of the present invention provides a photovoltaic assembly, comprising: a plurality of any of the aforementioned solar cells.

[0026] The above-mentioned solar cells and photovoltaic modules have the same or similar beneficial effects, which will not be described again here to avoid repetition. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0028] Figures 1 to 3 Schematic diagrams of partial structures of three solar cells in embodiments of the present invention are shown;

[0029] Figures 4 to 6 The partial SEM structural schematic diagrams of three solar cells in the embodiments of the present invention are shown.

[0030] Description of the accompanying drawings:

[0031] 1-silicon substrate, 12-tower base, 11-ridges of the tower base, 2-polysilicon doping layer, 3-tunneling oxide layer, 4-passivation anti-reflection layer, 5-electrode, 51-seed layer, 52-slurry layer, 6-opening, 71-contact area, 72-non-contact area, 73-transmission area of ​​the first transmission layer, 74-transmission area of ​​the second transmission layer, 8-isolation area, 9-hole. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The present invention provides a solar cell. In terms of the type of cell, the solar cell provided in the embodiments of the present application includes but is not limited to any of the following photovoltaic cells that can convert light energy into electrical energy. For example, the solar cell provided in the embodiments of the present application can be any of the following solar cells: a tunneling oxide passivated contact cell (Topcon), a doped polysilicon full back contact cell (TBC), a composite passivated back contact cell (HPBC), a double-sided hybrid cell, etc. Figure 1 , the solar cell comprises: a silicon substrate 1, a transmission layer and a passivation anti-reflection layer 4. In the thickness direction Q of the silicon substrate 1, the silicon substrate 1 has a first surface and a second surface opposite to each other. During the operation of the solar cell, the surface of the silicon substrate 1 that mainly receives light is its light-facing surface. In the thickness direction Q of the silicon substrate 1, the backlight surface and the light-facing surface are opposite to each other. Among the first surface and the second surface here, one surface can be the backlight surface of the silicon substrate 1, and the other surface can be the light-facing surface of the silicon substrate 1. For example, Figure 1The upper surface of the silicon substrate is the backlight surface of the silicon substrate. It should be noted that the 2 in the accompanying drawings refers to the polysilicon doping layer. Figure 1 The N-type polysilicon doping layer and the P-type polysilicon doping layer may be included.

[0034] A texture structure is arranged on the first surface of the silicon substrate 1, and the first surface here can be the light-facing surface or the backlight surface of the silicon substrate, which is not specifically limited. Figure 1 In the above, the first surface of the silicon substrate refers to its backlight surface. The texture structure here can refer to a tower base texture structure, or a texture structure of other shapes, for example, a regular or irregular texture structure composed of at least one straight ridge line and / or at least one curved ridge line. The texture structure usually has concave-convex changes at the ridge line.

[0035] It can be understood that in the solar cell, the film layer on the silicon substrate 1 is very thin. After the silicon substrate is covered with the transmission layer, the texture structure on the silicon substrate 1 will conformally be formed onto the transmission layer. On the surface of the transmission layer facing away from the silicon substrate, the above texture structure is still clearly visible. In the process of determining the above texture structure, the texture structure on the surface of the transmission layer facing away from the silicon substrate can be directly used as the basis, or the texture structure on the first surface of the silicon substrate 1 can be used as the basis.

[0036] The transmission layer and the passivation anti-reflection layer 4 are stacked on the texture structure of the first surface of the silicon substrate 1. The texture structure has a certain regular undulating feature. The silicon substrate is provided with a texture structure, and the transmission layer, passivation anti-reflection layer 4 and other film layers formed thereon have a larger contact area with the silicon substrate, which can achieve good passivation effects. The transmission layer here may include a P-type transmission layer and / or an N-type transmission layer. The P-type transmission layer and the N-type transmission layer may both be located on the texture structure of the backlight surface of the silicon substrate 1, in which case it is a back contact battery, or either the P-type transmission layer or the N-type transmission layer may be located on the texture structure of the first surface of the silicon substrate 1, and the other may be located on the second surface of the silicon substrate 1, in which case it is a double-sided contact battery. There is no limitation on the morphology of the second surface. There is no limitation on the specific material of the transmission layer. For example, refer to Figure 1 The transmission layer may include a polysilicon doping layer 2, a polysilicon region containing polysilicon in the polysilicon doping layer 2, the thickness of the polysilicon doping layer 2 may be 50nm to 250nm, and the direction of the thickness of the polysilicon doping layer 2, as well as the directions of the thickness mentioned in other structures in the present application, are parallel to the thickness direction Q of the silicon substrate 1 unless otherwise specified. Whether the transmission layer includes other layers is not specifically limited.

[0037] In the direction Q where the thickness of the silicon substrate 1 is located, the transmission layer is located between the silicon substrate 1 and the passivation anti-reflection layer 4. Figure 2 and Figure 3, the passivation anti-reflection layer 4 has a plurality of openings 6 at local positions, and the number of openings 6 in the passivation anti-reflection layer 4 is not specifically limited. The openings 6 in the present application may be other shapes such as circular, square or elliptical. Since the passivation anti-reflection layer has insulating properties, an opening area must be set, and the opening leaks out at least part of the transmission layer. In this way, an electrode can be formed at the opening by a low-temperature metallization process, which can reduce the cost of metallization. After the passivation anti-reflection layer 4 is provided with the openings 6, the area corresponding to the openings 6 on the side of the transmission layer facing away from the silicon substrate 1 will be exposed, refer to Figures 4 to 6 , the area corresponding to the opening 6 in the side of the transmission layer away from the silicon substrate 1 is the position where the transmission layer and the electrode contact each other, that is, the area corresponding to the opening 6 in the side of the transmission layer away from the silicon substrate 1 is the contact area 71, and the area outside the contact area 71 in the side of the transmission layer away from the silicon substrate 1 is the non-contact area 72. SEM image refers to scanning electron microscope image.

[0038] The maximum size of the opening 6 may refer to: the maximum size of the side of the opening 6 away from the silicon substrate, or the maximum size of the side of the opening 6 close to the silicon substrate, or the maximum size of a position between the side of the opening 6 away from the silicon substrate and the side close to the silicon substrate, or the average of at least two of the above maximum sizes of an opening; or the average of the maximum sizes of multiple openings. For example, if the opening 6 is a circular opening, the maximum size of the opening is the diameter of the circle; if the opening 6 is a square opening, the maximum size of the opening is the side length of the square.

[0039] In some embodiments, the shape of the opening 6 is at least one of a circle, a quasi-circle, a rectangle, and an ellipse, and the shape of the contact area 71 matches the shape of the opening 6 at the corresponding position. The opening 6 of the above shape is easy to achieve by laser opening. More importantly, in the process of the opening of the above shape by laser opening, the size and shape of the opening are easy to control, so that the shape and size of the opening are more accurate. It should be noted that the quasi-circle mentioned in this application means: approximately a circle. The shape of the opening 6 can also be a figure formed by splicing at least two of the shapes of circle, quasi-circle, rectangle, and ellipse, and there is no specific limitation on this.

[0040] The one-dimensional size of the texture structure may refer to: when a texture structure is a tower base, the one-dimensional size of the texture structure may refer to the side length of the tower base, or the diagonal of the tower base, or the average of the two; when a texture structure is a closed figure, the one-dimensional size of the texture structure may be one side length of the texture structure, or the average of multiple side lengths, or the diagonal of the closed figure, or the average of at least two of the foregoing; when a texture structure is a non-closed figure, the one-dimensional size of the texture structure may be one side length of the texture structure, or the average of multiple side lengths, or the total side length of the non-closed figure, or the average of at least two of the foregoing; or, the average of the one-dimensional sizes of multiple texture structures.

[0041] During the opening process, the passivation anti-reflection layer usually causes damage to the film layer below and around the opening. The texture structure on the first surface shows regular concave-convex changes, and the film layer on the raised ridges is more easily damaged. When the ratio of the maximum size of the opening to the one-dimensional size of the texture structure is greater than 5, the opening is too large, and the opening area covers too many texture structures. The opening process causes greater damage to the film layer below and around the opening, affecting the quality of the film layer, especially the passivation quality. When the ratio of the maximum size of the opening to the one-dimensional size of the texture structure is less than 0.5, the opening is too small. If the opening is too small, when an electrode is set above the opening, not only is the contact area between the electrode and the transmission layer exposed at the opening too small, affecting the collection and conduction of current or carriers, but the texture structure has a larger specific surface area and its raised ridges are rougher. If the opening is too small, the opening area covers too few texture structures, which also makes the opening The roughness is too small, resulting in poor bonding or contact between the electrode and the transmission layer; in the present application, the ratio of the maximum size of the opening to the one-dimensional size of the texture structure is 0.5 to 5, at least, the damage to the film layer below and around the opening during the opening process, as well as the balance of bonding and contact performance between the electrode and the transmission layer, the quality of the transmission layer, passivation anti-reflection layer and other film layers below and around the opening is good, and good passivation effects can be achieved; at the same time, the bonding between the electrode and the transmission layer is large, which prevents subsequent processes from pulling off, has strong reliability, and improves the bonding or contact effect between the electrode and the transmission layer, while reducing contact resistance, improving current collection and conduction effects, and thus improving the performance of solar cells. In summary, the present application achieves both good passivation effects and good contact performance.

[0042] For example, refer to Figure 5 The maximum size of an opening is d4. The texture structure can be considered as the base of the tower here. The side length d5 ​​of the base of the tower is the one-dimensional size of the texture structure here. At this time, d4 / d5 is the ratio of the maximum size of the opening to the one-dimensional size of the texture structure.

[0043] The passivation anti-reflection layer 4 mentioned in the present application can provide a good passivation anti-reflection effect, and its specific material is not limited. For example, the passivation anti-reflection layer 4 may include an aluminum oxide layer and a silicon nitride layer stacked, wherein the aluminum oxide layer is closer to the silicon substrate, the thickness of the aluminum oxide layer may be 4nm to 10nm, and the thickness of the silicon nitride layer may be 50nm to 150nm.

[0044] Optional, see Figure 2 and Figure 3 , the transmission layer includes: a first transmission layer and a second transmission layer, the doping types of the first transmission layer and the second transmission layer are different, that is, in this case, the first transmission layer and the second transmission layer are both located on the backlight surface of the silicon substrate or the texture structure of the first surface of the silicon substrate. The first transmission layer is one of the P-type transmission layer and the N-type transmission layer, and the second transmission layer is the other of the P-type transmission layer and the N-type transmission layer. For example, the first transmission layer is a P-type transmission layer, and the second transmission layer is an N-type transmission layer. For another example, the second transmission layer is a P-type transmission layer, and the first transmission layer is an N-type transmission layer. The maximum size of the opening in the corresponding area of ​​the first transmission layer is 1 to 5 times the one-dimensional size of the aforementioned texture structure; the maximum size of the opening in the corresponding area of ​​the second transmission layer is 0.5 to 5 times the one-dimensional size of the aforementioned texture structure. For the corresponding areas of the first transmission layer and the second transmission layer, the one-dimensional size of the texture structure can be the same or different, and for the corresponding areas of the first transmission layer and the second transmission layer in the passivation anti-reflection layer, the maximum sizes of the openings are different and are respectively within the corresponding ranges. Specifically, the degree of damage to the transmission layers of different materials during the opening process is different, and the contact performance between the transmission layers of different materials and the electrodes is also different. Here, mainly based on the different material properties of the first transmission layer and the second transmission layer, appropriate multiples of the one-dimensional size of the opening and the texture structure are selected. This is the result of the optimized balance between the damage to the corresponding transmission layer during the opening process and the contact performance between the transmission layer and the electrode. The corresponding transmission layer can withstand the damage caused by the opening, and the contact performance between the transmission layer and the electrode is good.

[0045] For example, the solar cell is a TBC solar cell, referring to Figure 1The TBC solar cell is a back contact solar cell, wherein the first transmission layer is a P-type transmission layer, specifically a P-type doped polysilicon layer, and the second transmission layer is an N-type transmission layer, specifically an N-type doped polysilicon layer, and a tunneling oxide layer 3 is provided between the first transmission layer and the second transmission layer and the silicon substrate 1. In the process of preparing the TBC solar cell, the P-type doped polysilicon layer can be prepared first, and then the N-type doped polysilicon layer can be prepared. In the TBC solar cell: the maximum size of the opening in the corresponding area of ​​the P-type doped polysilicon layer is 1 times, 1.2 times, 1.4 times, 1.5 times, 1.8 times, 2 times, 2.3 times, 2.5 times, 2.8 times, 2.9 times, 3 times, 3.2 times, 3.4 times, 3.5 times, 3.6 times, 3.9 times, 4 times, 4.5 times, and 5 times the one-dimensional size of the texture structure; the maximum size of the opening in the corresponding area of ​​the N-type doped polysilicon layer is 0.5 times, 0.7 times, 0.9 times, 1 times, 1.1 times, 1.3 times, 1.5 times, 1.8 times, 2 times, 2.2 times, 2.4 times, 2.5 times, 2.7 times, 2.8 times, 2.9 times, 3 times, 3.2 times, 3.3 times, 3.5 times, 3.6 times, 3.6 times, 4 times, 4.5 times, and 5 times the one-dimensional size of the texture structure.

[0046] Specifically, under the same opening process parameters, the P-type doped polysilicon layer may be less damaged than the N-type doped polysilicon layer, and the contact performance between the P-type doped polysilicon layer and the electrode may generally be slightly weaker than the contact performance between the N-type doped polysilicon layer and the electrode. Therefore, the maximum size of the opening of the corresponding area of ​​the P-type doped polysilicon layer in the passivation anti-reflection layer may be slightly larger, or equal to the maximum size of the opening of the corresponding area of ​​the N-type doped polysilicon layer to optimize the damage and contact performance. At the same time, the corresponding area of ​​the P-type doped polysilicon layer and the corresponding area of ​​the N-type doped polysilicon layer in the passivation anti-reflection layer may be opened as much as possible under the same opening process parameters to simplify the process and save production costs.

[0047] It should be noted that, in the process of determining that the maximum size of the opening in the area corresponding to the first transmission layer is a specific multiple of the one-dimensional size of the texture structure, the texture structure here can be the average one-dimensional size of the texture structure of the first surface, or it can be the one-dimensional size of any texture structure of the first surface, or it can be the one-dimensional size of any texture structure in the first surface corresponding to the first transmission layer, or it can be the average of the one-dimensional sizes of multiple texture structures in the first surface corresponding to the first transmission layer, or it can be the one-dimensional size of any texture structure in the first surface corresponding to the second transmission layer, or it can be the average of the one-dimensional sizes of multiple texture structures in the first surface corresponding to the second transmission layer, and there is no limitation on this. In the process of determining that the maximum size of the opening in the area corresponding to the first transmission layer is a specific multiple of the one-dimensional size of the texture structure, the texture structure here is similar to this and will not be repeated.

[0048] Optionally, the shape, size, and number of the openings in the area corresponding to the first transmission layer and the openings in the area corresponding to the second transmission layer may be the same or different. For example, the shape and size of the openings in the area corresponding to the first transmission layer and the openings in the area corresponding to the second transmission layer are exactly the same. With such a configuration, if a laser process is used, the opening path is simple and easy to process. Alternatively, the shape of the openings in the area corresponding to the first transmission layer and the openings in the area corresponding to the second transmission layer are the same, but the size and number are different. With such a configuration, it is easy to distinguish the first transmission layer from the second transmission layer, and to distinguish them in the subsequent processing process, thereby improving the process accuracy.

[0049] Optional, see Figure 2 and Figure 3 , the transmission layer includes several transmission areas, for example, the first transmission layer includes several transmission areas, and the second transmission layer includes several transmission areas. Figure 2 and Figure 3 In the figure, 73 may be a transmission area in the first transmission layer, and 74 may be a transmission area in the second transmission layer. The transmission area of ​​the first transmission layer and the transmission area of ​​the second transmission layer are alternately distributed along the direction L. In one transmission area, each opening 6 is arranged at intervals to form at least one opening row. In one transmission area, each opening 6 is arranged at intervals, so that there are corresponding openings at different positions on the transmission area, and the transmission distance of the current or carrier at each position of the transmission area is not too large, and the transmission loss is reduced as much as possible; when an opening row is formed, the corresponding opening process is relatively simple and the opening cost is relatively low.

[0050] Optional, see Figure 2 and Figure 3, in an opening row, the spacing d1 between adjacent openings 6 is 1 to 7 times the one-dimensional size of the texture structure. Specifically, in an opening row, the spacing d1 between adjacent openings 6 is less than 1 in ratio to the one-dimensional size of the texture structure. If d1 is too small, there are too many openings formed in a transmission zone, and the damage caused by the opening process is more. In addition, if the number of openings is too large, the opening area of ​​the texture structure covered becomes more, and the texture structure presents regular concave-convex changes. Its raised ridges are more likely to cause damage, further aggravating the degree of damage; in an opening row, the spacing d1 between adjacent openings 6 is greater than 7 in ratio to the one-dimensional size of the texture structure. If d1 is too large, there are too few openings formed in a transmission zone. When an electrode is set above the opening, on the one hand, the transmission distance of the current or carrier is too long, the transmission loss is large, and the current collection and conduction effect is poor. On the other hand, the roughness of the texture structure is greater, and the opening area of ​​the texture structure covered is too small, resulting in poor bonding or contact between the electrode and the transmission layer. Therefore, in an opening row, the spacing d1 between adjacent openings 6 is 1 to 7 times the ratio of the one-dimensional size of the texture structure, which is the result of a balance between the damage caused by the openings and the current collection and conduction effect. The damage caused by the openings is small and the current collection and conduction effect is good. The direction of d1 here is parallel to the extension direction of the transmission zone. d1 can be the spacing between the geometric centers of a pair of adjacent openings in an opening row, or d1 can be the average spacing between the geometric centers of multiple pairs of adjacent openings in an opening row.

[0051] For example, in one row of openings, the spacing d1 between adjacent openings 6 is 1 times, 1.5 times, 1.8 times, 2 times, 2.2 times, 2.5 times, 2.8 times, 3 times, 3.2 times, 3.5 times, 3.8 times, 4 times, 4.5 times, 4.7 times, 5 times, 5.2 times, 5.5 times, 5.8 times, 6 times, 6.5 times, or 7 times the one-dimensional size of the aforementioned texture structure.

[0052] Optionally, the value range of d1 here can be 10um to 100um. The basis of the actual value range of d1 is similar or the same as the basis or beneficial effect that the spacing d1 between adjacent openings in an opening row is 1 to 7 times the one-dimensional size of the texture structure. In order to avoid repetition, it will not be repeated here.

[0053] For example, d1 here can be 10um, 15um, 20um, 30um, 40um, 50um, 55um, 65um, 70um, 75um, 80um, 90um, or 100um.

[0054] It should be noted that, in the process of determining that the spacing d1 between adjacent openings in an opening row is a specific multiple of the one-dimensional size of the texture structure, the texture structure here can be the average one-dimensional size of the texture structure of the first surface, or, it can be the one-dimensional size of any texture structure on the first surface, or, it can be the one-dimensional size of any texture structure at a position on the first surface corresponding to the transmission layer, or, it can be the average value of the one-dimensional sizes of multiple texture structures at positions on the first surface corresponding to the transmission layer, or, the spacing between adjacent ones and the one-dimensional size of the texture structure directly below them, and there is no limitation on this.

[0055] Optional, see Figure 3 , in a transmission area, the number of opening rows is greater than or equal to 2, and the spacing d2 between adjacent opening rows is 0.5 to 5 times the one-dimensional size of the texture structure. The ratio of d2 to the one-dimensional size of the texture structure is less than 0.5. If d2 is too small, there are too many opening rows formed in a transmission area, and the damage caused by the openings is more, and the opening area covering the texture structure is increased, further increasing the damage; the ratio of d2 to the one-dimensional size of the texture structure is greater than 5. If d2 is too large, there are too few opening rows formed in a transmission area. On the one hand, the transmission distance of the current or carrier is too long, the transmission loss is large, and the current collection and conduction effect is poor. On the other hand, the opening area of ​​the texture structure covered is less, which makes the bonding force or contact effect of the electrode and the transmission layer poor. Therefore, the ratio of d2 to the one-dimensional size of the texture structure is 0.5 to 5, which is the result of the balance between the damage caused by the openings and the current collection and conduction effect. The damage caused by the openings is less and the current collection and conduction effect is good. The direction L where d2 is located is perpendicular to the extension direction M of the transmission area. d2 can be the distance between the geometric centers of two openings 6 in the adjacent opening rows in the direction L perpendicular to the extension direction M of the transmission area.

[0056] For example, d2 may be 0.5, 1, 1.3, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.9, 4, 4.2, 4.5, 4.7, or 5 times the one-dimensional size of the texture.

[0057] Optionally, the value range of d2 here can be 8um to 80um. The basis of the actual value range of d2 is the spacing between adjacent rows of openings, which is 0.5 to 5 times the one-dimensional size of the texture structure or the beneficial effects are similar or the same. In order to avoid repetition, it will not be repeated here.

[0058] For example, d2 here can be 8um, 10um, 15um, 20um, 23um, 25um, 30um, 32um, 35um, 37um, 40um, 45um, 47um, 50um, 55um, 60um, 65um, 70um, 75um, 80um.

[0059] It should be noted that, in the process of determining that the spacing between adjacent openings in an opening row is a specific multiple of the one-dimensional size of the texture structure, the texture structure here can be the average one-dimensional size of the texture structure of the first surface, or, it can be the one-dimensional size of any texture structure on the first surface, or, it can be the one-dimensional size of any texture structure at a position on the first surface corresponding to the transmission layer, or, it can be the average value of the one-dimensional sizes of multiple texture structures at positions on the first surface corresponding to the transmission layer, or, the spacing between adjacent openings and the one-dimensional size of the texture structure directly below them, and there is no limitation on this.

[0060] Optional, see Figure 3 In a transmission zone, the number of contact area rows is greater than or equal to 2, and the contact areas in adjacent contact area rows are staggered, that is, the number of opening rows at the location of a transmission zone is greater than or equal to 2, and the openings 6 in adjacent opening rows are staggered. Compared with the aligned arrangement of the openings 6 in adjacent opening rows, the staggered distribution makes the distribution of contact areas in a transmission zone more uniform, and then the transmission and collection distances of the current at each position in a transmission zone are roughly equal, which can achieve uniform collection and conduction of current, and the current collection and conduction effect is good, further ensuring the uniformity of current derivation.

[0061] For example, Figure 3 In one transmission area, the number of contact area rows is 2, and the contact areas in adjacent contact area rows are staggered. For another example, the number of contact area rows in one transmission area may also be 3, 4, 5, 6, etc., and the contact areas in adjacent contact area rows are staggered. Optionally, the number of contact area rows in one transmission area of ​​the first transmission layer and the number of contact area rows in one transmission area of ​​the second transmission layer may be the same or different, and may be flexibly adjusted according to the needs of actual applications.

[0062] Optionally, the aforementioned texture structure includes: a tower base, the tower base protrudes from the aforementioned first surface or is recessed in the aforementioned first surface; the one-dimensional size of the tower base is 5um to 40um. Specifically, the one-dimensional size of the tower base is related to the film-forming quality of the film layer thereon, and the bonding force or contact effect between the electrode 5 and the transmission layer. If the one-dimensional size of the tower base is too large, the film-forming quality of the film layer thereon will be poor, and the passivation effect will be poor. If the one-dimensional size of the tower base is too small, the gain effect on the bonding force or contact effect between the electrode 5 and the transmission layer will be poor. For the first transmission layer and the second transmission layer, the one-dimensional size of the tower base is 5um to 40um, which is an optimized balance of multiple factors such as the film-forming quality of the film layer thereon, the passivation effect, and the current collection and conduction effect, which can improve the performance of solar cells.

[0063] It can be understood that the shape of the tower base is related to the material of the silicon substrate and the texturing process. From the top view, its plane can be a polygon, for example, Figure 5 The square shown in the wireframe marked 12 in the figure is not limited thereto, and can also be at least one of a rhombus, a square, a trapezoid, an approximate rhombus, an approximate square, and an approximate trapezoid. The morphology of a suitable tower base is conducive to the subsequent formation of a good bonding force with the electrode. Similarly, in a solar cell, the film layer on the silicon substrate 1 is very thin. After the transmission layer is covered on the silicon substrate, the tower base on the silicon substrate 1 will basically conform to the transmission layer. On the surface of the transmission layer away from the silicon substrate, the tower base is still clearly visible. In the process of determining the tower base, the tower base on the surface of the transmission layer away from the silicon substrate can be directly used as the standard, or the tower base on the first surface of the silicon substrate 1 can be used as the standard.

[0064] For example, the one-dimensional size of the tower base can be 5um, 6um, 8um, 9um, 10um, 12um, 14um, 15um, 16um, 18um, 19um, 20um, 22um, 25um, 27um, 30um, 35um, 39um, 40um.

[0065] In some embodiments, the area outside the contact area 71 on the side of the transmission layer away from the silicon substrate 1 is a non-contact area 72; the roughness of the contact area 71 is greater than the roughness of the non-contact area 72. Specifically, the side of the transmission layer exposed in the opening away from the silicon substrate is the contact area 71, and the side of the doping layer not exposed in the opening away from the silicon substrate is the non-contact area 72. The roughness of the contact area 71 can affect the bonding force or contact effect between the electrode 5 and the transmission layer. Specifically, the rougher the contact area 71, the more obvious the effect of improving the bonding force or contact effect between the electrode 5 and the transmission layer. The greater the surface roughness of the transmission layer exposed in the opening, the larger the contact area between the transmission layer and the electrode, which is more conducive to reducing the contact resistance and improving the carrier transmission capacity; and the transmission layer in the non-contact area 72 also has a passivation anti-reflection layer, which does not directly contact the electrode 5. Here, the quality requirements of the transmission layer and the film layer thereon are higher, so the non-contact area 72 is relatively flat, and the quality of the film layer formed thereon is better, which can achieve a better passivation effect, etc., thereby improving the performance of the solar cell.

[0066] It should be noted that the roughness of the contact area 71 and the roughness of the non-contact area 72 may both refer to surface roughness, which may be Ra roughness or Rz roughness. The roughness of the contact area 71 and the roughness of the non-contact area 72 are determined in the same way.

[0067] Exemplarily, the Ra roughness of the contact area 71 can be 0, 0.05μm, 0.08μm, 0.1μm, 0.12μm, 0.15μm, 0.18μm, 0.2μm, 0.25μm, 0.29μm, 0.3μm, 0.33μm, 0.35μm, 0.38μm, 0.4μm, 0.43μm, 0.45μm, 0.5μm, and the Ra roughness of the non-contact area 72 can be 0, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm.

[0068] In some embodiments, reference Figures 4 to 6 The area corresponding to the opening on the side of the transmission layer facing away from the silicon substrate is the contact area 71, which is the location where the electrode and the transmission layer contact. At least one contact area 71 contains a part of the tower base. Figure 5In the figure, the roughly annular outline or structure in the wireframe marked 12 is a schematic diagram of the structure corresponding to the tower base in the transmission layer. Specifically, the transmission layer is located on the first surface, and the tower base on the first surface will be roughly conformal to the transmission layer. At least one contact area 71 may contain a complete tower base or a partial tower base. The larger the opening, the more tower bases there are in the contact area 71. The tower base contains ridges, and the ridges include the side lines of the tower base. The ridges here can be straight and / or curved. The contact area can also include a regular or irregular texture structure composed of at least one ridge, and the texture structure has concave and convex changes at the ridges. The more ridges corresponding to the area hit by the laser during the opening process, the greater the damage to the film layer below and around the opening may be. Therefore, the opening can be made as small as possible while satisfying the contact effect between the electrode and the transmission layer. In the present application, at least one contact area 71 contains a partial tower base, which means that there may be at least one contact area 71 that is not set on a complete tower base, and thus there are fewer corresponding tower bases in the contact area 71, resulting in less damage to the film layer below and around the opening, which can ensure the quality of the film layer, such as ensuring a good passivation effect, and can satisfy the contact effect between the electrode and the transmission layer.

[0069] Optionally, each tower base is arranged in a row along the extension direction of the transmission zone; and / or, each opening is spaced and arranged in a row along the extension direction of the transmission zone. Line marks are mainly cutting marks left by the cutting line in the process of cutting silicon wafers. The location where the tower base exists may be a place where etching is more serious during the polishing process. Each tower base is arranged in a row along the extension direction of the transmission zone, so the line marks can be removed as much as possible during the polishing process. The impact left by the line marks will be smaller, reducing the defects of the substrate and improving the performance of the solar cell. The extension direction of the transmission zone is parallel to the extension direction of the line marks. Therefore, the openings are spaced and arranged in a row along the extension direction of the transmission zone, or the extension direction of the aforementioned opening row is along the extension direction of the transmission zone. The area hit by the laser during the opening process may correspond to more line marks, and the undulating line marks can further increase the contact area between the transmission layer and the electrode, thereby improving the bonding force between the electrode and the transmission layer.

[0070] Optional, see Figures 4 to 6 , there is at least one hole 9 at the position of the ridge line 11 of the tower base 12 in the contact area 71. Specifically, the above-mentioned opening is usually formed by laser opening. During the laser opening process, the energy of the laser is not uniform enough, and the energy of the laser acting at certain positions is high, causing the transmission layer to explode here and form a hole 9. The hole 9 and the surrounding parts are rougher, further increasing the surface roughness and specific surface area of ​​the opening area, making the ridges of the surface have uneven characteristics, thereby further increasing the bonding force or contact effect of the electrode 5 and the transmission layer, improving the current collection and conduction effect, and thus improving the performance of the solar cell.

[0071] It should be noted that in the embodiment of the present application, the hole does not penetrate the transmission layer and is a blind hole.

[0072] Exemplarily, the maximum radial dimension of the hole 9 is greater than 0 μm and less than or equal to 3 μm. If the maximum radial dimension of the hole 9 is too large, for example, 3.5 μm, 4 μm or more, the number of holes 9 will be reduced, reducing the overall roughness of the contact area, thereby reducing the contact area between the transmission layer and the electrode, and reducing the bonding force between the electrode and the transmission layer. Therefore, the maximum radial dimension of the hole 9 in the present application is less than or equal to 3 μm.

[0073] It should be noted that, refer to Figures 4 to 6 The contact area 71 of the transmission layer except the ridge 11 of the tower base 12 may also be distributed with holes. The holes and the surrounding parts of the contact area 71 of the transmission layer except the ridge 11 of the tower base 12 are rougher, which also increases the surface roughness, thereby further increasing the bonding force or contact effect between the electrode 5 and the transmission layer, improving the current collection and conduction effects, and thus improving the performance of the solar cell.

[0074] Optional, see Figures 4 to 6 At least some of the holes 9 at the positions of the ridges 11 of the tower base in the contact area 71 are interconnected. After being interconnected, the relatively rough surfaces in the contact area 71 are interconnected, further increasing the bonding force or contact effect between the electrode 5 and the transmission layer, improving the current collection and conduction effects, and thus improving the performance of the solar cell.

[0075] It should be noted that in the present application, at least some of the holes 9 at the position where the ridge line 11 of the tower base in the contact area 71 is located are interconnected, which specifically means that at least two holes 9 at the position where the ridge line 11 of the tower base in the contact area 71 are interconnected, and the degree of interconnection is not limited. Figures 4 to 5 The distribution density of the interconnected holes at the position of the ridge line 11 of the tower base in the middle contact area 71 is relatively small. Figure 6 The distribution density of the holes connected to each other at the position of the ridge line 11 of the tower base in the middle contact area 71 is relatively large; or in other words, Figures 4 to 5 The number of holes connected to each other at the position of the ridge line 11 of the tower base in the middle contact area 71 is small. Figure 6 There are a large number of holes connected to each other at the positions where the ridge lines 11 of the tower base are located in the middle contact area 71. Figure 4 and Figure 5 In the contact area 71, the adjacent holes 9 at the position where the ridge line 11 of the tower base is located are adhered, Figure 6In the figure, the interconnectedness of the holes 9 at the position of the ridge line 11 of the tower base in the contact area 71 is higher, forming a bright line. The interconnectedness of the holes 9 at the position of the ridge line 11 of the tower base in the contact area 71 is specifically related to the laser power during the laser opening process. When the laser power is higher, the interconnectedness of the holes 9 at the position of the ridge line 11 of the tower base in the corresponding contact area 71 may be higher.

[0076] In some embodiments, reference Figures 4 to 6 , the density of holes at the ridges in the contact area 71 is greater than the density of holes in other areas. There are more holes 9 at the ridges in the contact area 71, and the holes 9 and the parts around them are rougher, which further increases the surface roughness and specific surface area of ​​the opening area, making the ridges on the surface have uneven characteristics, so that the contact area between the electrode 5 and the transmission layer is larger, thereby further increasing the bonding force or contact effect between the electrode 5 and the transmission layer, improving the current collection and conduction effect, avoiding the risk of the electrode and the transmission layer falling off, and thus improving the performance and reliability of the solar cell.

[0077] The density of holes at the edge of the contact area 71 refers to the number of holes per unit distance on the edge of the contact area 71, and the density of holes in other areas is similar. Figure 4 and Figure 5 In the contact area 71, at least some of the holes 9 at the position where the ridge line 11 is located are connected to each other, and the density of the holes at the ridge line is greater than the density of the holes in other areas.

[0078] Optionally, the transmission layer includes: a first transmission layer and a second transmission layer, and the doping types of the first transmission layer and the second transmission layer are different, and reference is made to the above-mentioned relevant records. In the first surface: the side length of the tower base in the second transmission layer is greater than the side length of the tower base in the first transmission layer; and / or, the depth of the tower base in the second transmission layer is less than the depth of the tower base in the first transmission layer. Specifically, the relative size relationship of the above dimensions is related to the number of etchings received by the corresponding transmission layer, the specific material, size, opening damage of the transmission layer, etc. In the case of the relative size relationship of the above dimensions, the damage to each film layer during the opening process is relatively small.

[0079] For example, the solar cell is a TBC solar cell, referring to Figure 1The TBC solar cell is a back contact solar cell, wherein the first transmission layer is a P-type transmission layer, specifically a P-type doped polysilicon layer, and the second transmission layer is an N-type transmission layer, specifically an N-type doped polysilicon layer. A tunneling oxide layer 3 is also provided between the first transmission layer and the second transmission layer and the silicon substrate 1. In the process of preparing the TBC solar cell, the P-type doped polysilicon layer can be prepared first, and then the N-type doped polysilicon layer can be prepared. In the TBC solar cell: the side length of the tower base in the P-type doped polysilicon layer is less than the length of the tower base in the N-type doped polysilicon layer; and / or, the depth of the tower base in the P-type doped polysilicon layer is greater than the depth of the tower base in the N-type doped polysilicon layer.

[0080] It should be noted that in the present application, the depth of the tower base refers to: when the tower base protrudes from other parts in the contact area, the depth of the tower base refers to the size of the tower base protruding from other parts in the contact area, which may be the size of the tower base protruding from other parts in the contact area at one position, or may be the average of the sizes of the tower base protruding from other parts in the contact area at multiple positions; when the tower base is recessed in other parts in the contact area, the depth of the tower base refers to the size of the tower base recessed in other parts in the contact area, which may be the size of the tower base recessed in other parts in the contact area at one position, or may be the average of the sizes of the tower base recessed in other parts in the contact area at multiple positions. The depth of the tower base in different transmission layers is determined in the same way.

[0081] In some embodiments, reference Figure 2 and Figure 3 In a transmission area, there is a gap between the contact area and the edge of the transmission area, that is, at the location of a transmission area, there is a gap between the opening 6 and the edge of the transmission area, and there is also a reserved position between the opening 6 and the edge of the transmission area. On the one hand, it is conducive to alignment during the opening process, and the processing window of the opening is larger. On the other hand, the thermal effect of the laser during the opening process can be avoided to affect the edge passivation, and the edge still has a good passivation effect.

[0082] In some embodiments, reference Figure 2 and Figure 3, on a transmission area, there is a gap between the contact area and the edge of the transmission area, and in the extension direction M of the transmission area, the size d3 of the gap is 50μm to 200μm. Specifically, when d3 is less than 50μm, the opening 6 is too close to the edge of the transmission area, which is not conducive to alignment during the opening process, and the processing window of the opening is small, the yield is low, and the opening 6 is too close to the edge of the transmission area. The thermal effect of the laser during the opening process will affect the edge passivation and weaken the edge passivation effect; when d3 is greater than 200μm, the opening 6 is too far from the edge of the transmission area, and the current or carrier transmission distance at the edge of the transmission area is too far, the transmission damage is large, and it is not conducive to the collection and conduction of current. Therefore, in the present application, d3 is 50μm to 200μm, which at least achieves a balance among multiple factors including the difficulty of alignment during the opening process, the processing window of the opening, the opening yield, edge passivation, and current collection at the edge of the transmission zone. It not only reduces the difficulty of alignment during the opening process and facilitates alignment, but also has a larger processing window for the opening and a higher yield. In addition, the thermal influence of the laser during the opening process basically does not affect the edge passivation, thereby maintaining a good passivation effect on the edge and ensuring the current collection effect at the edge of the transmission zone.

[0083] For example, in a transmission zone, there is a gap between the contact area and the edge of the transmission zone. In the extension direction M of the transmission zone, the size d3 of the gap can be: 50μm, 60μm, 80μm, 90μm, 100μm, 120μm, 150μm, 180μm, 190μm, 200μm.

[0084] Optionally, the maximum size d4 of the opening 6 is 10μm to 45μm, and the maximum size of the opening 6 is less than 10μm. If the maximum size of the opening 6 is too small, the contact effect between the electrode 5 and the transmission layer will be poor. The maximum size of the opening 6 is greater than 45μm. If the maximum size of the opening 6 is too large, the damage caused by the opening process will be too great. In the present application, the maximum size of the opening 6 is 10μm to 45μm, which is at least the result of an optimized balance between the contact effect between the electrode 5 and the transmission layer and the damage caused by the opening process. The contact effect between the electrode 5 and the transmission layer is good, and the damage caused by the opening process is small.

[0085] For example, the maximum dimension d4 of the opening 6 may be 10 μm, 10.5 μm, 11 μm, 12 μm, 13 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, 28 μm, 30 μm, 35 μm, 40 μm, or 45 μm.

[0086] Optional, see Figure 2 and Figure 3In the case where both the first transmission layer and the second transmission layer are located on the first surface of the silicon substrate, that is, both are located on the backlight surface of the silicon substrate, an isolation region 8 is further provided between the transmission regions 73 of the adjacent first transmission layer and the transmission regions 74 of the adjacent second transmission layer to avoid short circuit. The isolation region 8 may be a suede structure or a polished structure, which is not limited thereto. For example, the isolation region 8 may be a suede structure to increase the light trapping effect.

[0087] Optionally, the solar cell also includes: an electrode 5, where the electrode 5 can be an N-type electrode or a P-type electrode. The electrode 5 is arranged on the side of the passivation anti-reflection layer away from the silicon substrate, and the electrode 5 contacts the transmission layer through the opening 6. The electrode 5 in the present application may include a stacked seed layer 51 and a non-burn-through slurry layer 52. The slurry layer can be formed by low-temperature silver-coated copper slurry, low-temperature copper slurry, low-temperature nickel slurry, etc. The slurry layer uses low-temperature silver-free metallization technology, which not only avoids the price and supply disadvantages of silver paste products, but also saves resource consumption caused by high-temperature technology. At the same time, it can avoid the heat effect brought by high-temperature technology, which can effectively reduce production costs.

[0088] More specifically, the slurry layer 52 here can be selected from base metals, etc., which can reduce the cost of solar cells. The base metal here mainly refers to: not containing silver, or containing a very small amount of silver. For example, the slurry layer here can include: a copper slurry layer, an aluminum slurry layer, or a slurry layer with a mass content of precious metals less than 50%, and the precious metal here can include silver. For example, the slurry layer here can be a silver-coated copper slurry layer, etc.

[0089] The seed layer 51 may contain metal elements, and the metal elements may be selected from at least one of titanium (Ti), tungsten (W), chromium (Cr), nickel (Ni), cobalt (Co), molybdenum (Mo), tin (Sn), lead (Pb), palladium (Pd), copper (Cu), niobium (Nb), ruthenium (Ru), indium (In), zinc (Zn), tantalum (Ta), and vanadium (V). Specifically, the material of the seed layer 51 is selected from the above materials, and the resistance of the above materials, the barrier properties of the metal elements in the slurry layer 52, and other properties are more suitable for the seed layer. In particular, the material of the seed layer 51 is selected from nickel and / or zinc. On the first hand, nickel and zinc both have good contact properties; on the second hand, nickel and zinc basically do not penetrate into the silicon substrate, and the composite is less; on the third hand, nickel and zinc have a good barrier effect on the metal in the slurry layer 52 on the side away from the silicon substrate, which can prevent the metal in the slurry layer 52 from penetrating into the silicon substrate and reduce the composite. It should be noted that x in the above chemical formula is a number greater than 0.

[0090] The slurry layer 52 may contain base metals. Compared with solar cells using silver paste, the present application may perform metal plating, etc. For example, the cost of solar cells may be reduced by using nickel, copper, and tin metals with mature technology and low price instead of silver paste. For another example, the seed layer 51 may contain nickel, and the slurry layer may contain copper. Nickel has good contact properties, and nickel basically does not penetrate into the silicon substrate, and there is less recombination. In addition, nickel has a good barrier effect on the copper and other metals in the slurry layer 52 on the side away from the silicon substrate, which can prevent the copper and other metals in the slurry layer 52 from penetrating into the silicon substrate, reducing recombination and reducing costs. The solar cell in the present application can achieve good contact performance between the metal and the silicon substrate under low temperature conditions (below 300°C, such as about 200°C), without the need for high-temperature furnace sintering, and the heat effect brought into the solar cell is very small.

[0091] The present application also provides a method for preparing a solar cell, comprising the following steps.

[0092] Step 101, providing a silicon substrate; in the thickness direction of the silicon substrate, the silicon substrate has a first surface and a second surface opposite to each other; and a texture structure is disposed on the first surface.

[0093] Step 102: sequentially prepare a transmission layer and a passivation anti-reflection layer on the texture structure of the first surface.

[0094] The transmission layer can be formed by LPCVD (low pressure chemical vapor deposition) and other methods, and the specific formation method of the transmission layer is not limited. The preparation method of the passivation anti-reflection layer is not specifically limited, for example, deposition and other methods can be used.

[0095] Step 103, using laser opening to form a plurality of openings in the passivation anti-reflection layer; the area corresponding to the openings on the side of the transmission layer away from the silicon substrate is a contact area; the ratio of the maximum size of the opening to the one-dimensional size of the texture structure is 0.5 to 4.

[0096] There is no limitation on the specific parameters of the laser. For example, a picosecond laser engraving process can be used to engrave and open the passivation anti-reflection layer according to the designed collector grid line pattern to form the required micron-level groove structure.

[0097] The method may further include step 104 of forming an electrode at the opening, wherein the electrode is in contact with the transmission layer.

[0098] There is no specific limitation on the specific preparation method of the electrode. For example, a seed layer 51 may be prepared first, and then a slurry may be screen-printed on the side of the seed layer away from the silicon substrate and dried to form a slurry layer 52. The slurry layer may be formed by low-temperature silver-coated copper slurry, low-temperature copper slurry, low-temperature nickel slurry, etc. The slurry layer uses low-temperature silver-free metallization technology, which not only avoids the price and supply disadvantages of silver paste products, but also saves resource consumption caused by high-temperature technology. At the same time, it can avoid the heat effect brought by high-temperature technology, which can effectively reduce production costs.

[0099] Optionally, in the aforementioned step 103, a first laser power is used for laser opening to form a plurality of first openings; a second laser power is used for laser opening to form a plurality of second openings; at least one hole 9 is provided at the position where the ridge line 11 of the tower base is located in the contact area 71; at least some of the holes 9 at the position where the ridge line of the tower base is located in the contact area 71 are interconnected. The first laser power here is greater than the second laser power; the number of holes connected to each other at the position where the ridge line is located in the contact area corresponding to the first opening is greater than the number of holes connected to each other at the position where the ridge line is located in the contact area corresponding to the second opening; and / or, the distribution density of holes connected to each other at the position where the ridge line of the tower base is located in the contact area corresponding to the first opening is greater than the distribution density of holes connected to each other at the position where the ridge line of the tower base is located in the contact area corresponding to the second opening. That is, the greater the laser power, the greater the degree of connectivity of the holes connected to each other at the position where the ridge line of the tower base is located in the contact area. It should be noted that, in the comparison process here, the number of interconnected holes or the distribution density of interconnected holes is determined within the same area or unit area at the location of the tower base ridge line in the contact area.

[0100] The present application also provides a photovoltaic module, including any of the aforementioned solar cells. The photovoltaic module may also include packaging films located on both sides of the solar cell, etc., and other structures in the photovoltaic module are not specifically limited. The photovoltaic module may also include an electrical connector, and the electrical connector here can play a role of conductive interconnection. For example, the electrical connector can be a welding strip or a conductive backplane, etc., and there is no specific limitation on the electrical connector. The electrical connector is electrically connected to the aforementioned electrodes in at least two of the aforementioned solar cells. Here, the electrical connector can be directly electrically connected to the aforementioned electrodes, or indirectly electrically connected, and there is no limitation on this. The electrical connector can electrically connect the positive polarity electrode in one of the two adjacent aforementioned solar cells to the negative polarity electrode in the other solar cell to achieve conductive interconnection.

[0101] It should be noted that in the present application, the relevant parts among the photovoltaic module, the solar cell and the method for preparing the solar cell can be referenced to each other, and can achieve the same or similar beneficial effects. In order to avoid repetition, they will not be described here.

[0102] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0103] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A solar cell, characterized in that: include: Silicon substrate; In the direction of the thickness of the silicon substrate, the silicon substrate has a first surface and a second surface opposite to each other; A texture structure is arranged on the first surface; a transmission layer and a passivation anti-reflection layer are stacked on the texture structure; in the direction where the thickness of the silicon substrate is located, the transmission layer is located between the silicon substrate and the passivation anti-reflection layer; the passivation anti-reflection layer has a plurality of openings; and the ratio of the maximum size of the opening to the one-dimensional size of the texture structure is 0.5 to 5.

2. The solar cell according to claim 1, characterized in that The transmission layer comprises: a first transmission layer and a second transmission layer, wherein the first transmission layer and the second transmission layer have different doping types; The maximum size of the opening in the corresponding area of ​​the first transmission layer is 1 to 5 times the one-dimensional size of the texture structure; The maximum size of the opening in the corresponding area of ​​the second transmission layer is 0.5 to 5 times the one-dimensional size of the texture structure.

3. The solar cell according to claim 1, characterized in that The transmission layer includes a plurality of transmission areas, and in one of the transmission areas, the openings are arranged in intervals to form at least one opening row.

4. The solar cell according to claim 3, characterized in that: In one of the transmission areas, the number of the opening rows is greater than or equal to 2; and the spacing between adjacent opening rows is 0.5 to 5 times the one-dimensional size of the texture structure.

5. The solar cell according to claim 4, characterized in that: The openings in adjacent rows of openings are staggered.

6. The solar cell according to claim 3, characterized in that: In one row of the openings, the spacing between adjacent openings is 1 to 7 times the one-dimensional size of the texture structure.

7. The solar cell according to claim 1, characterized in that The texture structure comprises: a tower base; a one-dimensional size of the tower base is 5um to 40um.

8. The solar cell according to claim 7, characterized in that: On the side of the transmission layer facing away from the silicon substrate, the area corresponding to the opening is a contact area; and at least one hole is provided at the ridgeline of the tower base in the contact area.

9. The solar cell according to claim 7, characterized in that: The tower bases are arranged in a row along the extension direction of the transmission zone; and / or the openings are spaced apart and arranged in a row along the extension direction of the transmission zone.

10. The solar cell according to claim 8, characterized in that At least some of the holes at the ridges of the tower base in the contact area are connected to each other.

11. The solar cell according to claim 4, characterized in that: In one row of the openings, the interval between adjacent openings is 10 μm to 100 μm; and / or the interval between adjacent rows of the openings is 8 μm to 80 μm.

12. The solar cell according to claim 7, characterized in that: The transmission layer includes: a first transmission layer and a second transmission layer, the first transmission layer and the second transmission layer have different doping types; the side length of the tower base in the second transmission layer is greater than the side length of the tower base in the first transmission layer; and / or the depth of the tower base in the second transmission layer is less than the depth of the tower base in the first transmission layer.

13. The solar cell according to any one of claims 1 to 12, characterized in that: The maximum dimension of the opening is 10 μm to 45 μm.

14. The solar cell according to any one of claims 1 to 12, characterized in that: It also includes an electrode, which is arranged on a side of the passivation anti-reflection layer away from the silicon substrate, and the electrode contacts the transmission layer through the opening; the electrode includes a stacked seed layer and a non-burn-through slurry layer.

15. A photovoltaic module, characterized in that: include: A solar cell as claimed in any one of claims 1 to 14.

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