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 comprises a silicon substrate, a transmission layer and a passivation anti-reflection layer, the passivation anti-reflection layer is provided with a plurality of openings; the collector grid line is located at the opening and is in contact with the transmission layer; the collector grid line comprises a first seed region and a second seed region which are both arranged on the side, away from the silicon substrate, of the transmission layer, and the second seed region at least partially wraps the first seed region; the slurry layer is positioned on one side, deviating from the silicon substrate, of the second seed region; the slurry layer includes a base metal. The slurry layer contains the base metal, so that the cost of the solar cell can be effectively reduced. The first seed region in the collector grid line provides a bridge traction effect for the second seed region, so that the setting of the second seed region can be promoted; and meanwhile, the second seed region at least partially wraps the first seed region, so that the more compact second seed region can be formed, and the electrical property of the collector grid line can be 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] In solar cells, grid lines are mainly used to collect and conduct current. Currently, grid lines in solar cells are mostly silver grid lines formed by silver paste.

[0003] As the photovoltaic industry's market and production capacity continue to expand, the industry's demand for silver paste has also surged, and the price of silver paste has risen accordingly, leading to a continuous increase in the cost of solar cells. Summary of the invention

[0004] The invention provides a solar cell and a photovoltaic module, aiming to solve the problem of high cost caused by silver grid lines of existing solar cells.

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

[0006] A silicon substrate, wherein the silicon substrate has two opposite sides in a thickness direction of the silicon substrate;

[0007] A transmission layer and a passivation anti-reflection layer are stacked on at least one side of the silicon substrate;

[0008] The passivation anti-reflection layer has a plurality of openings;

[0009] A collector grid line passes through the opening position and contacts the transmission layer; the collector grid line includes: a seed layer and a slurry layer, the seed layer includes: a first seed region and a second seed region, both of which are arranged on the side of the transmission layer away from the silicon substrate, and the first seed region is closer to the silicon substrate; the second seed region at least partially wraps the first seed region; the slurry layer is arranged on the side of the second seed region away from the silicon substrate, and the slurry layer includes a base metal.

[0010] In this application, the paste layer contains base metals, which can effectively reduce the cost of solar cells. By first setting a first seed region, the first seed region usually contains metals, while the material in the transport layer is mainly semiconductor. The metals in the first seed region are more similar in nature to the metals in the second seed region, making it easier for the second seed region to form rapidly on the first seed region than on the transport layer. The first seed region plays a bridging and traction role, facilitating the more rapid setting of the second seed region on the transport layer to form a dense second seed region, enhancing the bonding between the second seed layer and the transport layer, and also helping to block the diffusion of the metals in the paste layer. Further, by at least partially wrapping the first seed region with the second seed region, the bonding area between the two is larger, which is more conducive to the rapid formation of the second seed region, and then a denser second seed region is formed. The dense second seed region can better block the diffusion of the base metals in the paste layer to the silicon substrate, and can improve the electrical performance of the collector grid lines. In summary, this application not only reduces the cost of solar cells, but also has good performance of the collector grid lines, with good current collection and conduction effects.

[0011] Optionally, the first seed region is located at the opening position, and the first seed region includes: one or more discontinuous portions.

[0012] Optionally, in at least one cross-section along the extending direction of the collector grid line or perpendicular to the extending direction of the collector grid line, the cross-section is perpendicular to the thickness direction of the silicon substrate, and in the cross-section, the first seed region has 80 to 500 discontinuous portions; and / or, the thickness of the first seed region is less than or equal to the thickness of the second seed region.

[0013] Optionally, the thicknesses of the discontinuous portions are not completely the same;

[0014] Optionally, the thickness of the discontinuous portion is less than or equal to 200 nm.

[0015] Optionally, the first seed region includes: at least one of zinc, platinum, gold, silver, chromium, rhodium, indium, nickel, palladium, and tin.

[0016] Optionally, at the edge of the opening, there is a gap between the transport layer and the passivation and antireflection layer, and the first seed region and / or the second seed region is present in the gap.

[0017] Optionally, along the direction away from the opening, the extending length of the gap is less than or equal to 5 μm.

[0018] Optionally, along the direction away from the silicon substrate, the second seed region at least partially covers the passivation and antireflection layer.

[0019] Optionally, the second seed region includes: metal elements and / or non-metal elements.

[0020] Optionally, the metal element is selected from at least one of titanium, tungsten, chromium, nickel, cobalt, molybdenum, tin, lead, palladium, copper, niobium, ruthenium, indium, zinc, tantalum, and

[0021] Optionally, the non-metal element includes at least one of phosphorus and boron.

[0022] Optionally, the mass percentage of phosphorus element in the second seed region is 2% to 8%.

[0023] Optionally, one side of the transport layer facing away from the silicon substrate has a raised portion.

[0024] Optionally, one side of the transport layer at the opening facing away from the silicon substrate has a number of first holes;

[0025] Optionally, a raised portion is formed at the edge of the first hole;

[0026] Optionally, a ring-shaped raised portion is formed at the edge of the first hole;

[0027] Optionally, the ring-shaped raised portion can be a closed ring or a non-closed ring;

[0028] The above-mentioned ring not only includes a strictly geometric circular ring, but also can be a similar ring shape, and can have arc segments with different curvatures.

[0029] Optionally, the first seed region aggregates at the raised portion of the transport layer.

[0030] Optionally, the first seed region aggregates at the raised portion of the first hole.

[0031] Optionally, the transport layer at the opening facing away from the silicon substrate has a number of first holes, and the distribution density of the first seed region on the inner wall and / or bottom of the first hole is less than the distribution density of the first seed region outside the first hole.

[0032] Optionally, the solar cell further includes: a bus bar, located on one side of the collector grid line facing away from the silicon substrate, and electrically connected to the collector grid lines of the same polarity and electrically isolated from the collector grid lines of different polarities.

[0033] In a second aspect of the present invention, a method for manufacturing a solar cell is provided, including:

[0034] Providing a silicon substrate; in the thickness direction of the silicon substrate, the silicon substrate has opposite two sides;

[0035] Preparing a transport layer on at least one side of the silicon substrate;

[0036] A passivation and antireflection layer is prepared on the side of the transmission layer away from the silicon substrate, and a plurality of openings are formed in the passivation and antireflection layer;

[0037] The transmission layer at the opening is processed, and a first seed region, a second seed region and a paste layer are provided on the side of the transmission layer at the opening away from the silicon substrate; the second seed region wraps the first seed region, and the paste layer includes base metals.

[0038] In a third aspect of the present invention, a photovoltaic module is provided, including: an electrical connector and any one of the foregoing solar cells;

[0039] The electrical connector is electrically connected to the current collecting grid lines in at least two of the solar cells.

[0040] The above-mentioned solar cell, its preparation method and photovoltaic module have the same or similar beneficial effects. To avoid repetition, they will not be elaborated here. Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0042] Figure 1 A side schematic view of a solar cell structure in an embodiment of the present invention is shown;

[0043] Figure 2 A SEM side view of a part of a solar cell in an embodiment of the present invention is shown;

[0044] Figures 3 to 5 A partially enlarged structural schematic view of a solar cell in an embodiment of the present invention is shown;

[0045] Figure 6 A SEM top view of a part of a transmission layer in an embodiment of the present invention is shown.

[0046] Description of the drawing reference numerals:

[0047] 1 - silicon substrate, 2 - P-type transmission layer, 21 - convex portion, 3 - N-type transmission layer, 4 - current collecting grid line, 5 - back surface passivation and antireflection layer, 6 - front surface passivation and antireflection layer, 7 - gap, 8 - first hole, 41 - first seed region, 42 - second seed region, 43 - paste layer, 9 - second hole. Detailed Embodiments

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0049] The present invention provides a solar cell. Referring to Figures 1 to 5 , the solar cell includes: a silicon substrate 1, a transport layer, a passivation and antireflection layer, and a collector grid line 4. In the thickness direction Q of the silicon substrate 1, the silicon substrate 1 has opposite sides. The side of the silicon substrate 1 that mainly receives light during the operation of the solar cell is its light-facing side. In the thickness direction Q of the silicon substrate 1, the backlight side and the light-facing side are opposite to each other. Figure 1 And Figure 2 In, the upper side of the silicon substrate 1 is its backlight side.

[0050] The transport layer and the passivation and antireflection layer are stacked on at least one side of the silicon substrate 1. The transport layer is closer to the silicon substrate 1 than the passivation and antireflection layer, that is to say, the passivation and antireflection layer is located on the side of the transport layer away from the silicon substrate. The transport layer here may include a P-type transport layer 2 and an N-type transport layer 3. Referring to Figure 1 , it may be that both the P-type transport layer 2 and the N-type transport layer 3 are located on the backlight side of the silicon substrate 1. In this case, the passivation and antireflection layer may include a back passivation and antireflection layer 5 and a front passivation and antireflection layer 6. Since Figure 1 In the back-contact solar cell shown, the collector grid lines are mainly arranged on the backlight side. Therefore, an opening is formed in the back passivation and antireflection layer 5 here; or, the P-type transport layer 2 may be located on one side of the silicon substrate 1, and the N-type transport layer 3 may be located on the other side of the silicon substrate 1. No specific limitation is made on the specific material of the transport layer. For example, the transport layer may include a doped polysilicon layer, and the thickness of the doped polysilicon layer may be 50 nm to 250 nm.

[0051] The passivation and antireflection layer has a plurality of openings. The collector grid line 4 passes through the opening position and contacts the transport layer; the collector grid line 4 can at least partially extend out of the opening. The collector grid line 4 includes: a seed layer, a paste layer. The seed layer includes: a first seed region 41 and a second seed region 42, both of which are arranged on the side of the transport layer away from the silicon substrate at the opening, and the first seed region 41 is closer to the silicon substrate 1; referring to Figure 3 And Figure 4 , the second seed region 42 at least partially wraps the first seed region 41; the paste layer 43 is located on the side of the second seed region 42 away from the silicon substrate. Referring to Figure 2 , the collector grid line 4 here may be only an N-type collector grid line; or, the collector grid line 4 here may be only a P-type collector grid line; or referring to Figure 1, the collector gate line 4 can be either an N-type collector gate line or a P-type collector gate line. It should be noted that the passivation anti-reflection layer 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 may include a stacked aluminum oxide layer and a silicon nitride layer, 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.

[0052] The mass of the slurry layer in the collector grid line usually accounts for most of the collector grid line. The slurry layer of the present application mainly uses base metals, which can effectively reduce the cost of solar cells compared to silver grid lines. By first setting the first seed area, the first seed area usually contains metals, and the material in the transmission layer is mainly semiconductors. The properties of the metal in the first seed area and the metal in the second seed area are more similar, so that the second seed area is easier to form quickly on the first seed area than on the transmission layer. Through the transition of the first seed area, it is beneficial for the second seed area to be set on the transmission layer more quickly to form a dense second seed area; further, by at least partially wrapping the first seed area with the second seed area, the bonding area between the two is larger, which is more conducive to the rapid formation of the second seed area, and then forming a denser second seed area. The dense second seed area can better block the base metal in the slurry layer from diffusing to the silicon substrate, and can improve the electrical performance of the collector grid line. In summary, the present application not only reduces the cost of solar cells, but also has good performance of the collector grid line, and good current collection and conduction effects.

[0053] It should be noted that the base metal here mainly refers to: does not contain silver, or contains a small amount of silver. For example, the slurry layer here may 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 may include silver. For example, the slurry layer here may be a silver-clad copper slurry layer, etc.

[0054] Optional, see Figure 1 , the first seed region 41 is located at the opening position, that is, the first seed region 41 is at least distributed in the opening, and the first seed region 41 forms a number of discontinuous parts on the side of the transmission layer away from the silicon substrate, that is to say, the first seed region 41 at an opening The transmission layer is not a continuous layer on the side away from the silicon substrate, and the first seed region 41 is not set as a whole layer at the opening position, which can save the raw materials of the first seed region 41 and save process costs. At the same time, the discontinuously distributed first seed region can also act as a bridge, pulling the second seed layer into shape and enhancing the bonding strength between the second seed layer and the transmission layer. Combining the above advantages, the discontinuously set first seed region can balance the cost, bonding strength and other performance of the collector grid line 4 as a whole.

[0055] Figures 1 to 3In the figure, the direction indicated by M is the width direction of the opening, and the direction indicated by Q is the thickness direction of the silicon substrate 1. Among them, Figure 3 is an enlarged schematic view of the edge of the opening of the solar cell, Figure 4 and Figure 3 is an enlarged schematic view of the part circled by the dashed circle in

[0056] Optionally, for at least one cross-section along the extending direction of the collector grid line or perpendicular to the extending direction of the collector grid line, this cross-section is perpendicular to the thickness direction of the silicon substrate. In this cross-section, the first seed region 41 has 80 to 500 discontinuous parts. At the opening position, if the distribution density of the first seed region 41 is too high, it will cause waste of raw materials and increase the process cost. If the distribution density of the first seed region 41 is too low, it will lead to insufficient traction transition effect of the first seed region, and it is difficult to form the second seed region 42, affecting the contact effect of the solar cell. In the present application, when the distribution density of the first seed region 41 is within the above range, it will not only cause waste of raw materials and has a relatively low cost, but also the traction transition effect of the first seed region 41 is more appropriate, which is beneficial to the formation of the second seed region 42, and the contact effect of the solar cell is good. It should be noted that here, for at least one cross-section along the extending direction of the collector grid line or perpendicular to the extending direction of the collector grid line, and this cross-section is perpendicular to the thickness direction of the silicon substrate. Specifically, this cross-section refers to the region where the horizontal projection area of the collector grid line coincides with the opening position. Along the extending direction of the collector grid line or perpendicular to the extending direction of the collector grid line, at least one cross-section is selected perpendicular to the thickness of the silicon substrate; since the distribution of the first seed region is not completely uniform, taking at least one cross-section to meet the distribution density of the aforementioned discontinuous parts is sufficient. The sampling position of this cross-section is the middle part close to the opening position, that is, the position where the opening width is larger, and the opening edge position needs to be avoided. For another example, on a cross-section perpendicular to the thickness direction of the silicon substrate, the first seed region 41 has 80, 90, 100, 120, 158, 159, 160, 180, 200, 220, 250, 280, 300, 320, 350, 400, 420, 450, 480, 500 discontinuous parts.

[0057] It should be noted that on a cross-section perpendicular to the thickness direction of the silicon substrate, along the width direction M of the opening, the width of each discontinuous part is greater than or equal to 10 nm, and those with a size less than 10 nm along the width direction of the opening in the first seed region 41 are not counted as a discontinuous part. Figure 1In order to facilitate drawing and display, in a cross-section along the thickness direction perpendicular to the silicon substrate, the number of intermittent parts in the first seed region 41 is a schematic after omission. In an actual solar cell, in a cross-section along the thickness direction perpendicular to the silicon substrate, the first seed region still has 80 to 500 intermittent parts.

[0058] Optionally, the thickness of the first seed region 41 is less than or equal to the thickness of the second seed region 42. Specifically, if the thickness of the first seed region 41 is too large, it will result in a large amount of raw material consumption and high cost. If the thickness of the first seed region 41 is too small, the traction transition effect of the first seed region will be insufficient, and it will be difficult for the second seed region 42 to be formed, affecting the contact effect of the solar cell. In this application, when the thickness of the first seed region 41 is within the above range, it will not only cause waste of raw materials and low cost, but also the transition effect of the first seed region 41 is more appropriate, which is conducive to the formation of the second seed region 42, and the contact effect of the solar cell is good.

[0059] It should be noted that the thickness directions of both the first seed region 41 and the second seed region 42 are parallel to the thickness direction Q of the silicon substrate.

[0060] It should be noted that Figure 1 As shown by Q, it is the thickness direction of the silicon substrate. In this application, in the thickness direction of the silicon substrate, the starting point of the setting of the first seed region 41 is the surface of the transmission layer facing away from the silicon substrate 1, and the thickness of the first seed region 41 refers to the size of the first seed region 41 in the thickness direction of the silicon substrate 1 starting from the surface of the transmission layer facing away from the silicon substrate 1. In the thickness direction of the silicon substrate 1, the starting point of the setting of the second seed region 42 may be the surface of the transmission layer facing away from the silicon substrate 1, or the surface of the first seed region 41 facing away from the silicon substrate 1. The thickness of the second seed region 42 may refer to the size of the second seed region 42 in the thickness direction of the silicon substrate 1 starting from the surface of the transmission layer facing away from the silicon substrate 1, or the thickness of the second seed region 42 may refer to the size of the second seed region 42 in the thickness direction of the silicon substrate 1 starting from the surface of the first seed region 41 facing away from the silicon substrate 1.

[0061] Regarding the measurement and evidence-taking methods for the thicknesses of the above two seed regions, specifically, in the thickness direction of the silicon substrate 1, the starting point of the setting of the first seed region 41 is the surface of the transmission layer facing away from the silicon substrate 1, and this surface can be a flat surface and / or a concave-convex surface. In the thickness direction of the silicon substrate, the starting point of the setting of the second seed region 42 is the surface of the transmission layer or the first seed region 41 facing away from the silicon substrate 1, and this surface can be a flat surface and / or a concave-convex surface. The surface of the first seed region 41 away from the transmission layer can be a flat surface and / or a concave-convex surface, and the surface of the second seed region 42 away from the transmission layer can be a flat surface and / or a concave-convex surface.

[0062] For example, when all four surfaces are merely flat surfaces, all four surfaces are perpendicular to the direction Q in which the thickness of the silicon substrate lies. At this time, the distance between any point on the surface of the transfer layer facing away from the silicon substrate 1 and any point on the surface of the first seed region 41 away from the transfer layer in the direction Q of the thickness of the silicon substrate can be used as the thickness of the first seed region 41. Alternatively, the average value of several thicknesses can be selected as the thickness of the first seed region 41. The method for obtaining the thickness of the second seed region 42 is the same as that of the first seed region 41.

[0063] For another example, when all four surfaces include concave-convex surfaces, the concave-convex surfaces can have peak structures and / or valley structures. At this time, the distance between the lowest / highest point among all the peak structures on the surface of the transfer layer facing away from the silicon substrate 1 and the lowest / highest point among all the peak structures on the surface of the first seed region 41 away from the transfer layer in the direction Q of the thickness of the silicon substrate can be used as the thickness of the first seed region 41. Alternatively, the average value of several thicknesses can be selected as the thickness of the first seed region 41. The method for obtaining the thickness of the second seed region 42 is the same as that of the first seed region 41.

[0064] For another example, when all four surfaces include concave-convex surfaces, the concave-convex surfaces can have peak structures and / or valley structures. At this time, the distance between the lowest / highest point among all the valley structures on the surface of the transfer layer facing away from the silicon substrate 1 and the lowest / highest point among all the valley structures on the surface of the first seed region 41 away from the transfer layer in the direction Q of the thickness of the silicon substrate can be used as the thickness of the first seed region 41. Alternatively, the average value of several thicknesses can be selected as the thickness of the first seed region 41. The method for obtaining the thickness of the second seed region 42 is the same as that of the first seed region 41.

[0065] In this application, the thicknesses of the first seed region 41 and the second seed region 42 can also be determined by selecting other vertices of the peak structures and valley structures of the above surfaces, which will not be elaborated here. It should be noted that in this application, during the process of thickness comparison, the determination methods of the several thicknesses to be compared are correspondingly the same. For the determination methods of other thicknesses in this application, they can all be referred to the foregoing examples and will not be elaborated here.

[0066] It should be noted that in this application, the thickness of the first seed region 41 is the thickness of the first seed region 41 whose projection is located within the aforementioned opening, and the thickness of the second seed region 42 is the thickness of the second seed region 42 whose projection is located within the aforementioned opening. The projection here refers to the projection on a plane perpendicular to the thickness direction of the silicon substrate.

[0067] Optionally, in the first seed region 41, the thickness of each discontinuous portion is not completely the same, which means that in the first seed region 41, there may be discontinuous portions with the same thickness and discontinuous portions with different thicknesses. Specifically, the thickness of the discontinuous portions is not completely the same, which is easy to prepare and can provide a good transition effect; and / or, in the first seed region 41, the thickness of the discontinuous portion is less than or equal to 200nm. Within this thickness range, the first seed region can already provide a good transition effect, and the thickness of the discontinuous portion is not too large, which will not cause waste of raw materials and has a low cost. At the same time, the discontinuous portions within this thickness range are easy to prepare. The direction of the thickness of the discontinuous portion is parallel to the thickness direction Q of the silicon substrate. The thickness of the discontinuous portion may refer to the maximum size of the discontinuous portion on the side of the silicon substrate in the thickness direction Q of the silicon substrate away from the silicon substrate, or it may be consistent with the aforementioned method of determining the thickness of the first seed region and the second seed region, and no specific limitation is made on this.

[0068] For example, in the first seed region 41, the thickness of the discontinuous part can be 200nm, 180nm, 150nm, 130nm, 160nm, 120nm, 110nm, 100nm, 90nm, 80nm, 70nm, 60nm, 50nm, 40nm, 30nm, 20nm, 10nm, 65nm, 75nm, 55nm, or 45nm.

[0069] Optionally, the first seed region 41 includes at least one of zinc (Zn), platinum (Pt), gold (Au), silver (Ag), chromium (Cr), rhodium (Rh), indium (In), nickel (Ni), palladium (Pd), and tin (Sn). The above metal elements have a low reduction barrier and are easily gathered in a point shape on the transmission layer, which is conducive to the formation of the second seed region 42. Moreover, the above elements also contain some base metal elements, which can further reduce costs.

[0070] Optional, see Figure 3 , at the edge of the opening, there is a gap 7 between the transmission layer and the passivation anti-reflection layer, refer to Figure 3 and Figure 4 , the first seed region 41 and / or the second seed region 42 extend into the gap 7, here only the first seed region may exist in the gap 7, or only the second seed region may exist in the gap 7, or may refer to Figure 3 and Figure 4 The first seed region 41 and the second seed region 42 are both present in the gap 7 , so that the contact area between the first seed region 41 and / or the second seed region 42 and the transmission layer is larger, and the contact effect is better.

[0071] Moreover, during the formation of the passivation and antireflection layer, hydrogen elements are usually formed in the passivation and antireflection layer. For example, when the material of the passivation and antireflection layer includes aluminum oxide, water participates in the reaction during the deposition of aluminum oxide, so excess hydrogen is generated. During the laser film opening process of the passivation and antireflection layer, hydrogen escapes under the influence of heat, and the process of hydrogen escape will cause film bursting, damaging the passivation and antireflection layer and the doped semiconductor layer, and affecting the passivation effect. The gap 7 in the present application is located at the edge of the passivation and antireflection layer close to the opening, which can provide space for hydrogen to escape during the laser film opening process, thereby facilitating the alleviation or avoidance of film bursting, reducing the damage caused by laser film opening, and effectively ensuring the passivation effect of the solar cell. The gap 7 here is mainly formed due to the thermal influence of laser film opening. Specifically, the passivation and antireflection layer in the unopened area near the opening edge is slightly warped, or the transfer layer has some micropores due to the pretreatment etching for forming the collector grid line 4, thus forming the above-mentioned gap.

[0072] Optionally, referring to Figure 3 , at the edge of the opening, there is also a second hole 9 in the gap 7 between the transfer layer and the passivation and antireflection layer. The second hole 9 here can also provide space for hydrogen to escape during the laser film opening process, thereby facilitating the alleviation or avoidance of film bursting, reducing the damage caused by laser film opening, and effectively ensuring the passivation effect of the solar cell.

[0073] Optionally, on one side of an opening, along the width direction M of the opening and in the direction away from the opening, the extension length of the gap 7 is less than or equal to 5 μm. If the extension length of the gap 7 on one side of an opening is too long, the passivation and antireflection layer is prone to cracking and falling off, which is not conducive to carrier transport and may cause excessive laser damage. On one side of an opening, when the extension length of the gap 7 along the width direction M of the opening is less than or equal to 5 μm, it not only has no adverse effect on carrier transport, but also has less laser damage. Moreover, the gap 7 with the above size can already provide sufficient space for hydrogen to escape in the passivation and antireflection layer, etc., effectively avoiding film bursting and improving the passivation effect. It should be noted that on one side of an opening, along the width direction M of the opening and in the direction away from the opening, the extension length of the gap 7 may refer to: along the width direction M of the opening and in the direction away from the opening, starting from the passivation and antireflection layer on one side of the opening to the farthest gap. For example, on one side of an opening, along the width direction M of the opening and in the direction away from the opening, the extension length of the gap 7 can be 5 μm, 4.5 μm, 4 μm, 3.5 μm, 3 μm, 2.5 μm, 2 μm, 1.5 μm, 1 μm, 0.5 μm.

[0074] Further, if the length of the gap 7 is too small, since hydrogen will escape during the laser film opening process and there is not enough space for hydrogen to escape, there is still a risk of film bursting. Therefore, in some examples, the length of the gap 7 is greater than or equal to 0.01 μm, and can be, for example: 0.01 μm, 0.012 μm, 0.014 μm, 0.016 μm, 0.018 μm, 0.02 μm, 0.38 μm, 0.58 μm, 0.78 μm, 0.98 μm, 1.9 μm, 2.9 μm, 3.9 μm or 5.9 μm.

[0075] Optionally, the distribution density of the second seed region 42 in the gap 7 is less than the distribution density of the second seed region 42 at the opening position. Specifically, in the gap 7, the volume ratio of the second seed region 42 is less than the volume ratio of the second seed region 42 at the opening position, that is, the distribution density of the second seed region 42 in the gap 7 is less than the distribution density of the second seed region 42 at the opening position. Specifically, the conduction of the current enters the slurry layer from the second seed region 42 at the opening. The distribution density of the second seed region 42 at the opening is greater, providing more current transmission channels and being more conducive to current conduction.

[0076] Optionally, the distribution density of the first seed region 41 in the gap 7 is greater than the distribution density of the second seed region 42 in the gap 7. Specifically, it can refer to that the volume ratio of the first seed region located in the gap to the gap 7 is greater than the volume ratio of the second seed region located in the gap to the gap 7. Therefore, the distribution density of the first seed region 41 in the gap 7 is greater than the distribution density of the second seed region 42 in the gap 7.

[0077] It should be noted that the distribution density of the first seed region 41 in the gap 7 can also be equal to the distribution density of the second seed region 42 in the gap 7; or, the distribution density of the first seed region 41 in the gap 7 can also be less than the distribution density of the second seed region 42 in the gap 7.

[0078] Optionally, referring to Figure 1 and Figure 2, the second seed region 42 at least partially covers the passivation and antireflection layer. That is to say, the second seed region 42 includes a portion corresponding to the opening and an extension portion extending from the opening to the side of the passivation and antireflection layer away from the silicon substrate, ensuring the adhesion of the second seed region 42 to the battery body and making it not easy to fall off; the second seed region 42 at least partially covering the passivation and antireflection layer can also increase the area of the upper surface of the second seed region 42, thereby increasing the contact area between the second seed region 42 and the passivation and antireflection layer, improving the adhesion between the second seed region 42 and the passivation and antireflection layer, and further reducing the risk of the second seed region 42 falling off; the second seed region 42 at least partially covering the passivation and antireflection layer can better block other elements such as water and oxygen from entering the battery at the opening, reducing the erosion or damage of the battery by other elements; in addition, the contact area between the extension portion and the paste layer in the battery thickness direction can be appropriately increased, that is, the contact area between the side surface of the extension portion and the paste layer is increased, further increasing the contact area between the second seed region 42 and the paste layer 43, reducing the contact resistance between the second seed region 42 and the paste layer 43, and reducing current loss. At the same time, not only in the direction perpendicular to the thickness direction of the silicon substrate, the second seed region 42 at least partially covers the passivation and antireflection layer, but also in the direction away from the silicon substrate 1: the second seed region 42 extends beyond the adjacent passivation and antireflection layer. Then the first seed region can be thinner. In the collector grid line 4, the portion other than the first seed region, namely the second seed region 42 and the paste layer 43, has a greater thickness. Since there are more choices for the second seed region 42 and the paste layer 43, base metals, etc. can be selected, which can further reduce costs.

[0079] It should be noted that all of the second seed region 42 may extend beyond the opening and cover the passivation and antireflection layer, or some regions of the second seed region 42 may extend beyond the opening and cover the passivation and antireflection layer. No specific limitation is made in this regard.

[0080] Optionally, the height d1 of the part where the second seed region 42 exceeds the adjacent passivation and antireflection layer is 200 nm to 1200 nm. Specifically, when d1 < 200 nm, the thickness of the extended part is too small at this time, which will increase the contact resistance between the second seed region 42 and the paste layer and may also have an adverse effect on the setting of the paste layer. When d1 > 1200 nm, the thickness of the extended part is too large at this time, which may have an adverse effect on the setting of the second seed region and the paste layer. For example, in the case where the second seed region and the paste layer are prepared in batches, when the height d1 of the part where the second seed region 42 exceeds the adjacent passivation and antireflection layer is less than 200 nm, it is not conducive to the setting of the paste layer. When the height d1 of the part where the second seed region 42 exceeds the adjacent passivation and antireflection layer is greater than 1200 nm, it is also not conducive to the setting of the paste layer. On the one hand, it is more appropriate that d1 is 200 nm to 1200 nm, the conductivity of the collector grid line is better, and it is conducive to the setting of the paste layer; on the other hand, in this height range, it can not only ensure sufficient adhesion between the second seed region 42 and the battery body to reduce the risk of detachment, but also ensure an appropriate contact area between the second seed region 42 and the paste layer and make the contact resistance between the second seed region 42 and the paste layer smaller; the second seed region 42 with the above thickness can better block other elements such as water and oxygen from entering the battery body at the opening, reducing the erosion or damage of other elements to the battery body; in addition, the contact area between the second seed region 42 and the paste layer in the thickness direction of the silicon substrate can be appropriately increased, that is, the contact area between the side surface of the second seed region 42 and the paste layer is increased, further increasing the contact area between the second seed region 42 and the paste layer, reducing the contact resistance between the second seed region 42 and the paste layer, and reducing current loss; this height range can also increase the area of the upper surface of the second seed region 42, thereby increasing the contact area between the second seed region 42 and the passivation and antireflection layer, improving the adhesion between the second seed region 42 and the passivation and antireflection layer, and further reducing the detachment risk of the second seed region 42.

[0081] For example, the height d1 of the part where the second seed region 42 exceeds the adjacent passivation and antireflection layer can be 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, 1100 nm, 1150 nm, 1200 nm.

[0082] It should be noted that the determination method of d1 here can refer to the determination method of the thickness of the first seed region and the second seed region mentioned above. To avoid repetition, it will not be elaborated here.

[0083] Optionally, the second seed region 42 includes: metal elements and / or non-metal elements, wherein the metal elements are mainly used to provide current collection and conduction functions; in the process of forming the second seed region 42 by redox reaction, the material containing the above-mentioned non-metal elements can play a reducing role, which can promote the replacement of silicon elements with metal elements, thereby facilitating the preparation of the second seed region 42.

[0084] Optionally, the metal element in the second seed region 42 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). One or more of them may be selected without specific limitation. In the second seed region 42, the above metal elements may exist in some compounds. For example, the second seed region 42 may contain titanium boride (TiB x ), tantalum nitride (Ta), tungsten nitride (WN x ), titanium nitride (TiN x ), titanium tungsten alloy (TiW x ), titanium silicon compounds (TiSi x ), titanium silicon nitride (TiSiN), tantalum silicon nitride (TaSiN x ), nickel vanadium (NiV). Specifically, the metal elements of the second seed region are selected from the above elements, and the properties of the above metal elements such as resistance and barrier properties to the metal elements in the slurry layer are more suitable for the second seed region. In particular, nickel and / or zinc are selected as the material of the second seed region. 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 there is less recombination; on the third hand, nickel and zinc have a good barrier effect on the metal in the slurry layer on the side away from the silicon substrate, which can prevent the metal in the slurry layer from penetrating into the silicon substrate and reduce recombination. It should be noted that x in the above chemical formula is a number greater than 0.

[0085] Optionally, the foregoing non-metallic elements include at least one of phosphorus and boron. It may contain phosphorus, or it may contain boron, or it may contain both phosphorus and boron. In the process of forming the second seed region 42 by redox reaction, some substances containing phosphorus and boron can play a good reducing role, which can promote the replacement of silicon elements by metal elements, facilitating the preparation of the second seed region 42. At the same time, when the non-metallic element contains phosphorus, an N-type heavy doping is set in the second seed region 42, which is more conducive to transporting the carriers derived from the N-type transport layer, while reducing recombination and increasing the open-circuit voltage. Moreover, the above phosphorus element is directly introduced during the formation of the collector grid line without additional process steps, saving process steps. When the non-metallic element contains boron, a P-type heavy doping is set in the second seed region 42, which is more conducive to transporting the carriers derived from the P-type transport layer, while reducing recombination. Moreover, the above boron element is directly introduced during the formation of the collector grid line without additional process steps, saving process steps.

[0086] For example, boron in the above non-metallic elements can exist in sodium borohydride and / or dimethylamine borane. For another example, phosphorus in the above non-metallic elements can exist in sodium hypophosphite. During the process of forming the second seed region 42 by redox reaction, the above materials can also play a reducing role, which can promote the replacement of silicon elements by metal elements, facilitating the preparation of the second seed region 42.

[0087] Optionally, when the second seed region 42 contains phosphorus, the mass ratio of phosphorus element in the second seed region 42 is 2% to 8%. If the mass content of phosphorus element is too high, the contact performance between the slurry layer 43 and the second seed region 42 may deteriorate, affecting the electrical performance of the battery. When the mass content of phosphorus element is too low, the amount of the reducing agent containing phosphorus participating in the reaction is too low, the triggering conditions of the entire redox reaction are harsh and the reaction is slow, affecting the production efficiency. When the second seed region 42 contains phosphorus, the mass ratio of phosphorus element in the second seed region 42 is 2% to 8%, which is the result of balancing the contact performance and the reaction rate.

[0088] It should be noted that one or more regions can be selected arbitrarily from the second seed region 42, and the size of the region is not limited. Here, the mass ratio of phosphorus element in one region can be used as the mass ratio of phosphorus element in the second seed region 42, or the average value of the mass ratios of phosphorus element in multiple regions can be used as the mass ratio of phosphorus element in the second seed region 42.

[0089] For example, when the second seed region 42 contains phosphorus, the mass ratio of phosphorus element in the second seed region 42 can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%.

[0090] Figure 5 is a schematic diagram of the raised portion of the transmission layer. Figure 5 The transmission layer has a protrusion 21 on the side away from the silicon substrate 1, and the first seed region 41 is gathered at the protrusion. The protrusion 21 here can be the ridge of the tower base on the surface of the silicon substrate, which causes the transmission layer to have a protrusion on the side away from the silicon substrate 1, or the transmission layer has a protrusion near the position corresponding to the ridge of the tower base on the surface of the silicon substrate on the side away from the silicon substrate, or the protrusion here can be a protrusion formed by processing to form an opening, which is not limited. The first seed region 41 is gathered at the protrusion, and then the first seed region 41 is more likely to form a three-dimensional structure at the protrusion position, rather than a two-dimensional structure, and then the combination of the first seed region 41 and the second seed region 42 is more firm, and the contact performance is better.

[0091] The shape of the protrusion is not particularly limited. Figure 5 is a cross-sectional view of the transmission layer, where the cross section is a cross section formed by cutting the transmission layer along the direction of the thickness of the silicon substrate. Figure 5 The shape of the protrusion 21 on the left side is a columnar protrusion. Figure 5 The raised portion in the middle may be a dot-shaped raised portion. Figure 5 The raised portion on the right side may be an annular raised portion; for example, Figure 6 In the figure, the shape of the protrusion under the topmost first seed region 41 is dot-shaped. Figure 6 The shape of the raised portion located in the middle in the vertical direction under the marked first seed region 41 is prismatic. Figure 6 The shape of the protrusion under the first seed region 41 at the bottom is annular. It should be noted that Figure 5 and Figure 6 The shapes of the protrusions are not fully shown in the figure, and the shapes of the protrusions include but are not limited to the aforementioned columnar, dot-shaped, prismatic, and annular shapes. The annular protrusions here can be continuously distributed as a closed ring, or discontinuously distributed as a non-closed ring, and there is no limitation on this. The above-mentioned ring shape includes not only a circular ring shape in a strict geometric sense, but also a ring-like shape, and can have arc segments with different curvatures.

[0092] Optional, see Figure 5 and Figure 6, the transmission layer at the opening has a plurality of first holes 8 on the side away from the silicon substrate, and the edge of the first hole forms a non-closed protrusion with a shape similar to a ring. The first seed region 41 gathers at the edge of the first hole 8, and the first seed region 41 exists as a transitional part of the second seed region 42, and then the second seed region 42 will be preferentially formed near the edge of the first hole 8. Specifically, the first hole 8 is due to the fact that the energy of the laser is not uniform enough during the laser opening process, and the energy of the laser acting at the position of the first hole 8 is high, causing the transmission layer to explode here and then form the first hole 8, so the transmission layer at the edge of the first hole 8 will melt and recrystallize, and has higher activity, so it is easier to form the second seed region here; in addition, the first seed region 41 gathers at the edge of the first hole 8, and then the first seed region 41 is more likely to form a three-dimensional structure at the edge of the first hole 8, rather than a two-dimensional structure, and then the first seed region 41 and the second seed region 42 are more firmly combined and have better contact performance.

[0093] Optional, see Figure 6 The transmission layer at the opening has a plurality of first holes 8 on the side facing away from the silicon substrate; Figure 6 It can be seen that the protrusions of the first holes are either closed rings or non-closed rings. Figure 6 In the first hole 8 marked on the far right, the distribution density of the first seed region 41 on the inner wall and / or the bottom of the first hole 8 is less than the distribution density of the first seed region 41 outside the first hole 8. Specifically, in the process of forming the first seed region 41, it is necessary to immerse the transmission layer at the opening in the reaction liquid. The inner wall and / or the bottom of the first hole 8 may be less likely to be infiltrated into the reaction liquid than the outside of the first hole. Therefore, the distribution density of the first seed region 41 on the inner wall and / or the bottom of the first hole 8 is less than the distribution density of the first seed region 41 outside the first hole 8, and then the second seed region 42 will be preferentially formed outside the first hole 8. In the process of forming the second seed region, the outside of the first hole 8 is also usually easier to contact the reaction raw materials, so it is easier to form the second seed region here, which is more compatible with the formation process of the second seed region; in addition, the first seed region 41 gathers outside the first hole 8, and then the first seed region 41 is more likely to form a three-dimensional structure outside the first hole 8, rather than a uniformly distributed two-dimensional layer structure, and then the combination of the first seed region 41 and the second seed region 42 is more firm, and the contact performance is better.

[0094] It should be noted that it is easier to form raised protrusions outside the first hole 8 and near the edge of the first hole 8 during the opening process. The above-mentioned protrusions can be distributed continuously or discontinuously, so that no matter in the process of forming the first seed area or the second seed area, the reaction raw materials are more likely to contact the above-mentioned protrusions, and due to the catalytic effect of the first seed area, the second seed area will also be formed here preferentially, which is more compatible with the formation process of the second seed area; on the other hand, the first seed area is more likely to gather into a three-dimensional structure rather than a two-dimensional structure here, so that the combination of the first seed area 41 and the second seed area 42 is more firmly bonded and the contact performance is better.

[0095] Optionally, the solar cell further includes: a busbar line, which is located on the side of the collector grid line 4 facing away from the silicon substrate, and is electrically connected to the collector grid line 4 of the same polarity, and is electrically isolated from the collector grid line 4 of a different polarity. The electrical isolation here can be achieved by an insulating member or the like. Optionally, the busbar line may include: a slurry layer, and the busbar line will conduct the current on the collector grid line 4. The slurry layer of the busbar line here contains base metals, etc., which can reduce costs. The slurry layer of the busbar line can be formed in the same step as the slurry layer of the collector grid line, and both can be base metals, which not only simplifies the process but also saves costs; or, the slurry layer of the busbar line can be formed in different steps with the slurry layer of the collector grid line, and the respective process parameters are accurately controlled according to the required performance of each. In this case, the slurry layer of the busbar line can also be a slurry layer containing base metals, which can also reduce costs. It should be noted that the solar cell may not include a busbar line, or have fewer busbar lines.

[0096] The present application also provides another solar cell, comprising: a silicon substrate 1, wherein the silicon substrate has two opposite sides in the thickness direction of the silicon substrate 1; a transmission layer and a passivation anti-reflection layer, which are stacked on at least one side of the silicon substrate; the passivation anti-reflection layer has a plurality of openings; the collector grid line is located at the opening position and is in contact with the transmission layer; the collector grid line contains metal elements and / or non-metal elements, wherein the metal elements here can play a good conductive effect, and the non-metal elements here can promote the formation of the collector grid line on the transmission layer at the opening position. The non-metal elements here can include: at least one of phosphorus and boron, wherein the roles played by phosphorus and boron here are similar or the same as those in the aforementioned related records, and in order to avoid repetition, they will not be described here.

[0097] For example, an optional collector grid line may include: the aforementioned second seed region, the second seed region including: metal elements and / or non-metal elements, the metal elements and non-metal elements here can refer to the aforementioned related records, and can achieve the same or similar beneficial effects. In order to avoid repetition, they will not be repeated here.

[0098] For another example, another optional collector grid line may be based on including: the aforementioned second seed region, the second seed region including: metal elements and / or non-metallic elements, the collector grid line may also include the aforementioned first seed region, the second seed region at least partially wraps the first seed region, the first seed region and the second seed region here can refer to the aforementioned relevant records, and can achieve the same or similar beneficial effects, in order to avoid repetition, they will not be repeated here.

[0099] The silicon substrate, transmission layer, passivation anti-reflection layer, opening, opening location, metal elements, non-metal elements, etc. here can refer to the above-mentioned related records accordingly, and can achieve the same or similar beneficial effects. In order to avoid repetition, they will not be repeated here.

[0100] There is no limitation on the specific form of the collector grid line herein. Except for the collector grid line, other structures in the solar cell can refer to other structures in the aforementioned solar cell.

[0101] For example, in the solar cell, at the edge of the opening, along the width direction of the opening, there is a gap between the transmission layer and the passivation anti-reflection layer, and part of the collector grid line exists in the gap. For another example, on one side of an opening, along the direction of the opening away from the opening, the extension length of the gap is less than or equal to 5μm. For another example, the metal element in the collector grid line can be selected from: at least one of titanium, tungsten, chromium, nickel, cobalt, molybdenum, tin, lead, palladium, copper, niobium, ruthenium, indium, zinc, tantalum and vanadium. For another example, the solar cell may also include: a busbar line, which is located on the side of the collector grid line away from the silicon substrate, and is electrically connected to the collector grid line of the same polarity and electrically isolated from the collector grid line of different polarity. In the solar cell, the specific details of each feature, and the role played by each feature, are the same or similar to the role played by the corresponding features in the aforementioned solar cell, and can refer to the corresponding features in the aforementioned solar cell, and will not be repeated here.

[0102] The present application also provides a method for preparing a solar cell, comprising the following steps.

[0103] Step 101: providing a silicon substrate; in a thickness direction of the silicon substrate, the silicon substrate has two opposite sides.

[0104] Step 102: Prepare a transmission layer on at least one side of the silicon substrate.

[0105] The transmission layer may be formed by LPCVD (low pressure chemical vapor deposition) or other methods, and the specific method for forming the transmission layer is not limited.

[0106] Step 103: prepare a passivation anti-reflection layer on the side of the transmission layer facing away from the silicon substrate and form a plurality of openings in the passivation anti-reflection layer.

[0107] The opening method here can be laser or wet etching, and no specific limitation is imposed thereon. For example, a picosecond laser engraving process can be used to engrave and open the film on the passivation and antireflection layer according to the designed collector grid pattern to form the required micron-level groove structure.

[0108] Step 104: Pretreat the transfer layer at the opening, and dispose a seed layer and a slurry layer on the side of the transfer layer at the opening away from the silicon substrate. The seed layer includes: a first seed region and a second seed region; the first seed region is closer to the silicon substrate; the second seed region at least partially wraps the first seed region, and the slurry layer includes base metals.

[0109] The pretreatment here is used to enhance the activity of the transfer layer at the opening. The second seed region can be formed by redox reaction or electrochemical reaction. The first seed region provides functions such as transition during the formation of the second seed region. Compared with the electrochemical reaction, the redox reaction method for preparing the second seed region can further reduce costs. The slurry layer can be formed by screen printing first and then drying. The slurry layer can be selected from low-temperature silver-coated copper paste, low-temperature copper paste, low-temperature nickel paste, etc. The selection of the low-temperature silver-free metallization technology for the slurry layer not only avoids the price and supply disadvantages of silver paste products, but also saves the resource consumption brought by high-temperature technology, and at the same time can avoid the thermal influence brought by high-temperature technology, and can effectively reduce production costs.

[0110] The present application also provides a photovoltaic module, including: an electrical connector and any one of the foregoing solar cells. The electrical connector here can play a role of conductive interconnection. For example, the electrical connector can be a solder ribbon or a conductive backplane, etc., and no specific limitation is imposed on the electrical connector. The electrical connector is electrically connected to the collector grid lines in at least two of the foregoing solar cells. Here, it can be that the electrical connector is directly electrically connected to the collector grid lines or indirectly electrically connected, and no limitation is imposed thereon. The electrical connector can electrically connect the positive-polarity collector grid lines in one of the two adjacent foregoing solar cells to the negative-polarity collector grid lines in the other solar cell to achieve conductive interconnection.

[0111] The photovoltaic module may further include encapsulation adhesive films on both sides of the solar cell, etc., and no specific limitation is imposed on other structures in the photovoltaic module.

[0112] It should be noted that in the present application, the relevant parts among the photovoltaic module, the solar cell, and the preparation method of the solar cell can be referred to each other, and the same or similar beneficial effects can be achieved. To avoid repetition, it will not be elaborated here.

[0113] The present application will be further explained below with specific embodiments.

[0114] Embodiment

[0115] In the first step, a silicon substrate is provided, wherein the silicon substrate comprises an opposite backlight surface and a light-facing surface in a thickness direction Q. The backlight surface comprises a first conductive region and a second conductive region, and an isolation region may exist between the first conductive region and the second conductive region to avoid short circuit.

[0116] The second step is to prepare a transmission layer. Specifically, a P-type transmission layer 2 is prepared on the side of the first conductive area of ​​the backlight surface of the silicon substrate away from the silicon substrate, and an N-type transmission layer 3 is prepared on the side of the second conductive area away from the silicon substrate. The N-type transmission layer 3 includes N-type doped polysilicon.

[0117] In the third step, a back passivation anti-reflection layer is prepared on the side of the N-type transmission layer 3 and the P-type transmission layer 2 facing away from the silicon substrate.

[0118] The fourth step is to use picosecond laser engraving technology 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, that is, to form an opening.

[0119] The fifth step is to pre-treat the transmission layer at the opening, and set a first seed area, a second seed area and a slurry layer on the side of the transmission layer at the opening away from the silicon substrate, and simultaneously set a busbar line, and the second seed area wraps the first seed area.

[0120] Among them, the first seed region 41 is intermittently distributed on the side of the transmission layer at an opening away from the silicon substrate. The width of an opening is about 80μm. Along the width direction M of the opening, on a cross section that passes through the opening and is perpendicular to the thickness direction of the silicon substrate, the first seed region 41 has 159 intermittent parts. In the first seed region, the thickness of the intermittent part is less than or equal to 200nm, and on the side of the transmission layer at an opening away from the silicon substrate, the average thickness of the intermittent part is about 40nm. The second seed region 42 is prepared by oxidation-reduction method, and the slurry layer 43 and the busbar line are prepared by screen printing and drying, and the drying temperature is 200℃. The slurry layer 43, the second seed region 42 and the busbar line all contain base metals. The non-metallic elements in the second seed region 42 include phosphorus, and in the second seed region 42, the mass proportion of phosphorus is 5%. On one side of an opening, along the width direction M of the opening, there is a gap 7 between the transmission layer and the passivation anti-reflection layer, and both the first seed region and the second seed region extend into the gap 7. On one side of an opening, along the width direction M of the opening and in the direction away from the opening, the extension length of the gap is about 3 μm. In the direction away from the silicon substrate: the second seed region at least partially covers the passivation anti-reflection layer, and the second seed region 42 exceeds the adjacent passivation anti-reflection layer; the height d1 of the portion of the second seed region 42 that exceeds the adjacent passivation anti-reflection layer is about 500 nm. The structure of the solar cell formed in the embodiment is roughly similar to Figure 1as shown

[0121] For the solar cell formed in the embodiment, good contact performance between the metal and the silicon substrate is achieved under low-temperature conditions (below 300 °C, such as around 200 °C), without high-temperature furnace sintering, and the thermal influence brought into the solar cell is very small. For the solar cell formed in the embodiment, measurements are carried out under national standard conditions. Among them, the contact resistance of the first conductive region is less than or equal to 0.8 mΩ×cm 2 , and the contact resistance of the second conductive region is less than or equal to 0.1 mΩ×cm 2 , which is superior to the solar cells of the related art.

[0122] It should be noted that in this article, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without further limitations, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the element.

[0123] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the purpose of the present invention and the scope protected by the claims. All of these fall within the protection scope of the present invention.

Claims

1. A solar cell, characterized in that, include: A silicon substrate, wherein the silicon substrate has two opposite sides in a thickness direction of the silicon substrate; A transmission layer and a passivation anti-reflection layer are stacked on at least one side of the silicon substrate; The passivation anti-reflection layer has a plurality of openings; The collector grid line contacts the transmission layer through the opening position; The collector grid line includes: a seed layer and a slurry layer, the seed layer includes: a first seed region and a second seed region, both of which are arranged on the side of the transmission layer away from the silicon substrate, and the first seed region is closer to the silicon substrate; the second seed region at least partially wraps the first seed region; the slurry layer is arranged on the side of the second seed region away from the silicon substrate, and the slurry layer includes a base metal.

2. The solar cell according to claim 1, characterized in that, The first seed region is located at the opening position, and the first seed region includes one or more discontinuous parts.

3. The solar cell according to claim 2, wherein, At least one cross section along the extending direction of the collector gate line or perpendicular to the extending direction of the collector gate line, wherein the cross section is perpendicular to the thickness direction of the silicon substrate, and the first seed region has 80 to 500 discontinuous parts in the cross section; And / or, the thickness of the first seed region is less than or equal to the thickness of the second seed region.

4. The solar cell according to claim 2 or 3, characterized in that, The thickness of the discontinuous parts is not completely the same; and / or the thickness of the discontinuous parts is less than or equal to 200 nm.

5. The solar cell according to claim 1, wherein The first seed region includes at least one of zinc, platinum, gold, silver, chromium, rhodium, indium, nickel, palladium and tin.

6. The solar cell according to claim 1, characterized in that, At the edge of the opening, there is a gap between the transmission layer and the passivation anti-reflection layer, and the first seed region and / or the second seed region exists in the gap.

7. The solar cell according to claim 6, characterized in that, Along a direction away from the opening, an extension length of the gap is less than or equal to 5 μm.

8. The solar cell according to claim 1, wherein, Along a direction away from the silicon substrate, the second seed region at least partially covers the passivation anti-reflection layer.

9. The solar cell according to claim 1, wherein The second seed region includes: metal elements and / or non-metal elements.

10. The solar cell according to claim 9, characterized in that, The metal element is selected from at least one of titanium, tungsten, chromium, nickel, cobalt, molybdenum, tin, lead, palladium, copper, niobium, ruthenium, indium, zinc, tantalum and vanadium.

11. The solar cell according to claim 9, characterized in that, The non-metallic element includes at least one of phosphorus and boron.

12. The solar cell according to claim 11, characterized in that, The mass percentage of phosphorus in the second seed region is 2% to 8%.

13. The solar cell according to claim 1, characterized in that, The transmission layer has a protrusion on a side facing away from the silicon substrate, and the first seed regions are gathered at the protrusion.

14. A photovoltaic module, characterized in that, include: An electrical connector and a solar cell as claimed in any one of claims 1 to 13; The electrical connector is electrically connected to the collector grid lines in at least two of the solar cells.

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