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 doping layer is located on at least one side of the silicon substrate in the thickness direction of the silicon substrate; the passivation layer is arranged on the P-type doped layer and the N-type doped layer; the ohmic contact part of the P-type collector electrode and the doping layer comprises a plurality of first metal crystals, and the width of the distribution area of the first metal crystals is A1 in the width direction of the P-type collector electrode; the ohmic contact part of the N-type collector electrode and the doping layer comprises a plurality of second metal crystals, the distribution area width of the second metal crystals is A2 in the width direction of the N-type collector electrode, and A1 is larger than A2. The ohmic contact distribution area formed by the P-type collector electrode and the P-type doping layer is larger, so that collection of carriers in the P-type doping layer is improved, the difference of the carriers in the two doping layers is reduced, and the performance of the battery is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic technology, in particular to a solar cell and a photovoltaic module. BACKGROUND

[0002] The solar cell is a device that directly converts light energy into electrical energy through photoelectric effect, etc. It has broad application prospects because it uses clean energy.

[0003] In the solar cell, the collecting electrode is usually in contact with the doped layer to achieve current collection and conduction.

[0004] However, the current collection and conduction effect in the existing solar cell is poor, which affects the performance of the solar cell. SUMMARY

[0005] The present application provides a solar cell and a photovoltaic module, aiming to solve the problem of poor positioning effect in the existing back contact cell.

[0006] In a first aspect of the present application, a solar cell is provided, comprising:

[0007] a silicon substrate;

[0008] a doped layer located on at least one side of the silicon substrate along the thickness direction of the silicon substrate, the doped layer comprising a P-type doped layer and an N-type doped layer;

[0009] a passivation layer disposed on the P-type doped layer and the N-type doped layer;

[0010] a P-type collecting electrode located on the side of the P-type doped layer away from the silicon substrate, the P-type collecting electrode extending into the P-type doped layer through the passivation layer and forming an ohmic contact with the P-type doped layer, the ohmic contact part of the P-type collecting electrode with the doped layer comprising a plurality of first metal crystals, along the width direction of the P-type collecting electrode, the distribution area width of the first metal crystals is A1;

[0011] an N-type collecting electrode located on the side of the N-type doped layer away from the silicon substrate, the N-type collecting electrode extending into the N-type doped layer through the passivation layer and forming an ohmic contact with the N-type doped layer, the ohmic contact part of the N-type collecting electrode with the doped layer comprising a plurality of second metal crystals, along the width direction of the N-type collecting electrode, the distribution area width of the second metal crystals is A2, wherein A1>A2.

[0012] In the present application, firstly, in a solar cell, the doping concentration of the P-type doped layer is generally less than that of the N-type doped layer. Along the width direction of the P-type collecting electrode, the distribution area width A1 of the first metal crystal is larger, the first metal crystal covers a wider range in the P-type collecting electrode, the coverage of the ohmic contact between the P-type collecting electrode and the P-type doped layer is wider, the distribution area of the ohmic contact between the P-type collecting electrode and the P-type doped layer is larger, the electrical connection effect between the P-type collecting electrode and the P-type doped layer is better, thereby improving the collection effect of the current or carrier in the P-type doped layer, offsetting the influence of the lower doping concentration in the P-type doped layer, thereby reducing the difference in the current or carrier between the two doped layers and improving the performance of the cell. Secondly, the first metal crystal covers a wider range in the P-type collecting electrode, the coverage of the ohmic contact between the P-type collecting electrode and the P-type doped layer is wider, the bonding force and pulling force between the P-type collecting electrode and the P-type doped layer are improved, the difference between the bonding force and pulling force between the P-type collecting electrode and the P-type doped layer and the bonding force and pulling force between the N-type collecting electrode and the N-type doped layer is reduced, thereby reducing the risk of pulling off due to insufficient bonding force of the P-type collecting electrode electrically connected to the P-type doped layer. Thirdly, the first metal crystal covers a larger range in the P-type collecting electrode, which can effectively reduce the contact resistance corresponding to the P-type collecting electrode, further reduce the difference between the contact resistances corresponding to the P-type collecting electrode and the N-type collecting electrode, and improve the performance of the cell.

[0013] In some possible embodiments, along the width direction of the P-type collecting electrode, the distribution density of the first metal crystal in the first metal crystal distribution area is B1, and along the width direction of the N-type collecting electrode, the distribution density of the second metal crystal in the second metal crystal distribution area is B2, B1 < B2.

[0014] In the present application, B1 is smaller, the first metal crystal is more sparse in the first metal crystal distribution area, the transport or diffusion path of the carrier is approximately the same and relatively short, and the recombination probability is relatively small. On the other hand, B2 is larger, the second metal crystal is more dense in the second metal crystal distribution area, the transport or diffusion path of the carrier at some positions is relatively long, resulting in a relatively large recombination, thereby reducing the difference in the current or carrier between the two doped layers and improving the performance of the cell. At the same time, the bonding force and pulling force between the P-type collecting electrode and the P-type doped layer are improved, the difference between the bonding force and pulling force between the P-type collecting electrode and the P-type doped layer and the bonding force and pulling force between the N-type collecting electrode and the N-type doped layer is reduced, thereby reducing the risk of pulling off due to insufficient bonding force of the P-type collecting electrode electrically connected to the P-type doped layer.

[0015] In some possible embodiments, the number of the first metal crystals along the width direction of the P-type collecting electrode is C1, and the number of the second metal crystals along the width direction of the N-type collecting electrode is C2, and C1>C2.

[0016] The number of the first metal crystals along the width direction of the P-type collecting electrode is C1, and the number of the first metal crystals along the width direction of the P-type collecting electrode is C1, and C1>C2.

[0017] In some possible embodiments, the size of the first metal crystal is greater than the size of the second metal crystal.

[0018] The size of the first metal crystal along the width direction of the P-type collecting electrode is C1, and the number of the first metal crystals along the width direction of the P-type collecting electrode is C1, and C1>C2.

[0019] In some possible embodiments, the first metal crystal extends into the P-type doped layer by a depth of D1, and the second metal crystal extends into the N-type doped layer by a depth of D2, and D1>D2.

[0020] The depth D1 of the first metal crystal extending into the P-type doped layer is deeper, the first metal crystal in the P-type collector electrode forms an ohmic contact deeper, the electrical connection effect of the P-type collector electrode and the P-type doped layer is better, and the collection effect of the current or carrier in the P-type doped layer is improved, so as to offset the influence of the lower doping concentration in the P-type doped layer, and the difference between the carriers or currents in the two doped layers is reduced, and the performance of the battery is improved. At the same time, the bonding force and pulling force between the P-type collector electrode and the P-type doped layer are improved, and the difference between the bonding force and pulling force between the P-type collector electrode and the P-type doped layer and the bonding force and pulling force between the N-type collector electrode and the N-type doped layer is reduced, so as to reduce the risk of pulling off due to insufficient bonding force of the P-type collector electrode electrically connected with the P-type doped layer.

[0021] In some possible embodiments, the ratio of the number of the first metal crystals extending into the P-type doped layer to the total number of the first metal crystals is greater than the ratio of the number of the second metal crystals extending into the N-type doped layer to the total number of the second metal crystals.

[0022] The number of ohmic contact points formed by the first metal crystals in the P-type collector electrode is greater, the P-type collector electrode and the P-type doped layer form more conductive channels at the contact position, the electrical connection effect of the P-type collector electrode and the P-type doped layer is better, and the collection effect of the current or carrier in the P-type doped layer is improved, so as to offset the influence of the lower doping concentration in the P-type doped layer, and the difference between the carriers or currents in the two doped layers is reduced, and the performance of the battery is improved. At the same time, the bonding force and pulling force between the P-type collector electrode and the P-type doped layer are improved, and the difference between the bonding force and pulling force between the P-type collector electrode and the P-type doped layer and the bonding force and pulling force between the N-type collector electrode and the N-type doped layer is reduced, so as to reduce the risk of pulling off due to insufficient bonding force of the P-type collector electrode electrically connected with the P-type doped layer.

[0023] In some possible embodiments, the first metal crystal at the position closest to the side surface of the P-type doped layer near the silicon substrate has a vertical distance E1.

[0024] The second metal crystal at the position closest to the side surface of the N-type doped layer near the silicon substrate has a vertical distance E2; E1 < E2.

[0025] The first metal crystal in the P-type collecting electrode forms an ohmic contact deeper, and the electrical connection effect of the P-type collecting electrode and the P-type doped layer is better, thereby improving the collection effect of the current or carrier in the P-type doped layer, offsetting the influence of the lower doping concentration in the P-type doped layer, and thereby reducing the difference in the carriers or current in the two doped layers, and improving the performance of the battery.

[0026] In some possible embodiments, the ratio of the depth of the first metal crystal extending into the P-type doped layer to the thickness of the P-type doped layer is F1, and the ratio of the depth of the second metal crystal extending into the N-type doped layer to the thickness of the N-type doped layer is F2, where F1>F2.

[0027] The first metal crystal in the P-type collecting electrode forms an ohmic contact deeper, and the electrical connection effect of the P-type collecting electrode and the P-type doped layer is better, thereby improving the collection effect of the current or carrier in the P-type doped layer, offsetting the influence of the lower doping concentration in the P-type doped layer, and thereby reducing the difference in the carriers or current in the two doped layers, and improving the performance of the battery; at the same time, the bonding force and pulling force between the P-type collecting electrode and the P-type doped layer are improved, and the difference between the bonding force and pulling force between the P-type collecting electrode and the P-type doped layer and the bonding force and pulling force between the N-type collecting electrode and the N-type doped layer is reduced, so as to reduce the risk of pulling off due to insufficient bonding force of the P-type collecting electrode electrically connected to the P-type doped layer.

[0028] In some possible embodiments, the P-type collecting electrode comprises a first seed layer and a first base metal layer, the first seed layer is electrically connected to the P-type doped layer through the passivation layer, and the first base metal layer covers the first seed layer and is electrically connected to the P-type doped layer through the first seed layer; the first base metal layer comprises a plurality of metal particles, and the first seed layer comprises a plurality of first metal crystals; and / or,

[0029] The N-type collecting electrode comprises a second seed layer and a second base metal layer, the second seed layer is electrically connected to the N-type doped layer through the passivation layer, and the second base metal layer covers the second seed layer and is electrically connected to the N-type doped layer through the second seed layer; the second base metal layer comprises a plurality of metal particles, and the second seed layer comprises a plurality of second metal crystals.

[0030] Firstly, the base metal layer replaces the noble metal, which can reduce the cost of the battery; secondly, compared with the noble metal, some base metals in the base metal layer are more likely to diffuse, and the seed layer is closer to the silicon substrate, which can block the inward diffusion of the base metals in the base metal layer, and can greatly avoid the problem of recombination caused by the further diffusion of the metal elements in the base metal layer into the interior of the silicon substrate.

[0031] In some possible embodiments, the first seed layer has a height greater than a height of the second seed layer; and / or,

[0032] The first seed layer has a width greater than a width of the second seed layer.

[0033] The bonding force and pulling force between the first seed layer electrically connected to the P-type doped layer and the first base metal layer electrically connected to the P-type doped layer are further enhanced, the bonding force between the P-type collector electrode electrically connected to the P-type doped layer and the electrical connector is also enhanced, and the difference between the bonding force and the pulling force between the P-type collector electrode and the P-type doped layer and between the N-type collector electrode and the N-type doped layer is reduced, so as to reduce the risk of pulling off due to the imbalance of the bonding force of the P-type collector electrode electrically connected to the P-type doped layer. In addition, the current collection capability of the region where the P-type doped layer is located is also improved, so as to reduce the current difference between the P-type doped layer and the N-type doped layer, and avoid the local current loss. That is, a higher and wider first seed layer is arranged on the P-type doped layer with a higher resistivity. Such arrangement can further improve the conductivity of the corresponding region of the silicon substrate and the P-type doped layer, reduce the contact resistivity, better balance the conduction carrier between the N region and the P region, and thus reduce the influence of the imbalance of the doping concentration of the P-type doped layer on the electrical performance

[0034] In some possible embodiments, the P-type collector electrode has a height less than a height of the N-type collector electrode; and / or,

[0035] The P-type collector electrode has a width less than a width of the N-type collector electrode.

[0036] In some possible embodiments, the seed layer is a honeycomb structure including a plurality of holes, and at least part of the metal particles are partially filled in the honeycomb structure in the same collector electrode.

[0037] The seed layer and the base metal layer are nested with each other. On the one hand, the contact performance of the seed layer and the base metal layer is improved, the conductivity of the collector electrode is improved, and the pulling force and the structural stability at the interface of the seed layer and the base metal layer are improved. On the other hand, compared with noble metals, some base metals in the base metal layer are more likely to diffuse, and the holes in the seed layer can be used as receiving positions or accommodation positions for the inward diffusion of the metal elements in the base metal layer, so as to greatly avoid the problem of recombination caused by the further diffusion of the metal elements in the base metal layer to the inside of the silicon substrate.

[0038] In some possible embodiments, the size of the holes of the P-type collector electrode is greater than the size of the holes of the N-type collector electrode.

[0039] In the case that the size range of the metal particles in the two is the same, more metal particles will enter the holes in the first seed layer electrically connected to the P-type doped layer, and the nesting degree of the first seed layer electrically connected to the P-type doped layer and the first base metal layer electrically connected to the P-type doped layer at the holes is greater, further enhancing the binding force and pulling force between the first seed layer electrically connected to the P-type doped layer and the first base metal layer electrically connected to the P-type doped layer. In the present application, the size of the holes in the first seed layer electrically connected to the P-type doped layer is larger, further enhancing the binding force and pulling force between the first seed layer electrically connected to the P-type doped layer and the first base metal layer electrically connected to the P-type doped layer, reducing the difference between the binding force and pulling force between the P-type collector electrode and the P-type doped layer and the binding force and pulling force between the N-type collector electrode and the N-type doped layer, so as to reduce the risk of pulling off due to the imbalance of the binding force of the P-type collector electrode electrically connected to the P-type doped layer. In addition, under normal circumstances, it is difficult to obtain a high doping concentration of the P-type doped layer, therefore, in the present application, by enhancing the binding force and pulling force between the first seed layer electrically connected to the P-type doped layer and the first base metal layer electrically connected to the P-type doped layer, the current collecting capacity of the region where the P-type doped layer is located is improved, and the influence of the imbalance of the doping concentration of the P-type doped layer on the electrical performance is reduced.

[0040] In some possible embodiments, the size of the metal particles in the P-type collector electrode is the same as the size of the metal particles in the N-type collector electrode.

[0041] In some possible embodiments, the material of the base metal layer is selected from at least one of Cu, Al, Ni, and silver-coated copper.

[0042] Firstly, the above-mentioned materials have good electrical conductivity; secondly, the above-mentioned materials have low cost, which can reduce the cost of the electrode; and thirdly, the above-mentioned materials can be formed by low-temperature process, avoiding the penetration of the burn-through passivation layer into the silicon substrate, reducing the recombination, and avoiding the introduction of heat into the solar cell.

[0043] In some possible embodiments, the material of the seed layer is selected from one or more of Al, Zn, Fe, Co, Mg, Ag, Ni, Au, and Pd, and in the same collector electrode, the material of the seed layer is different from that of the base metal layer.

[0044] In some possible embodiments, the seed layer is continuously or partially discontinuously arranged along the extension direction of the collector electrode, and the base metal layer is continuously arranged along the extension direction of the collector electrode.

[0045] In some possible embodiments, the back surface of the silicon substrate comprises a first region and a second region, the first region and the second region are arranged alternately, the first region is provided with the P-type doped layer, and the second region is provided with the N-type doped layer; or,

[0046] The P-type doped layer is arranged on the front surface of the silicon substrate, and the N-type doped layer is arranged on the back surface of the silicon substrate.

[0047] In a second aspect of the present application, a photovoltaic module is provided, comprising: a plurality of cell strings connected in series and / or in parallel, the cell string comprising: an electrical connector and any one of the preceding solar cells, the electrical connector electrically connecting at least two of the solar cells.

[0048] The photovoltaic module and the solar cell have the same or similar beneficial effects, and for the sake of brevity, the same will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0050] Figures 1 to 4 The structure schematic diagrams of four kinds of solar cells in the embodiments of the present application are shown;

[0051] Figure 5 、 Figure 7 、 Figure 8 The SEM comparison diagrams of the P-type collecting electrode and the N-type collecting electrode in the embodiments of the present application are shown;

[0052] Figure 6 The comparison schematic diagrams of the P-type collecting electrode and the N-type collecting electrode in the embodiments of the present application are shown;

[0053] Figure 9 The partial SEM diagrams of the P-type collecting electrode in the embodiments of the present application are shown;

[0054] Figure 10 The partial SEM diagrams of the N-type collecting electrode in the embodiments of the present application are shown;

[0055] Figure 11 The structure schematic diagram of the P-type collecting electrode in the embodiments of the present application is shown.

[0056] EXPLANATION OF DRAWINGS:

[0057] 1 - silicon substrate, 2 - P-type doped layer, 3 - N-type doped layer, 4 - passivation layer, 5 - P-type collector electrode, 51 - first seed layer, 52 - first base metal layer, 53 - first metal crystal, 6 - N-type collector electrode, 61 - second seed layer, 62 - second base metal layer, 63 - second metal crystal, 7 - tunneling layer. DETAILED DESCRIPTION

[0058] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0059] The present application provides a solar cell, referring to Figures 1 to 4 The solar cell comprises a silicon substrate 1, a doped layer, a passivation layer 4, a P-type collector electrode 5 and an N-type collector electrode 6. The silicon substrate 1 can be N-type monocrystalline silicon or P-type monocrystalline silicon, which can provide long-life carriers. For example, the silicon substrate 1 is N-type monocrystalline silicon. The silicon substrate 1 comprises a first side and a second side opposite along the thickness direction L1 of the silicon substrate 1, one of which is a light side and the other is a back light side. The side of the silicon substrate 1 mainly receiving light during the operation of the solar cell is the light side, and the back light side is opposite to the light side. For example, Figure 1 and Figure 2 In the above, the upper side of the silicon substrate 1 is the light side, and the lower side is the back light side. The doped layer comprises a P-type doped layer 2 and an N-type doped layer 3. The doped layer is located on at least one side of the silicon substrate 1 along the thickness direction L1 of the silicon substrate 1. For example, Figure 1 and Figure 2 In the above, the P-type doped layer 2 and the N-type doped layer 3 are respectively located on different sides of the silicon substrate 1, which is a bifacial solar cell. For another example, Figure 3 and Figure 4 In the above, the P-type doped layer 2 and the N-type doped layer 3 are both located on the same side of the silicon substrate 1, which is a back contact solar cell.

[0060] The P-type doped layer 2 can contain one or more of the Group IIIA elements (e.g., boron). The N-type doped layer 3 can contain one or more of the Group VA elements (e.g., phosphorus). The materials of the N-type doped layer 3 and the P-type doped layer 2 can include any of silicon, silicon germanium, germanium, or gallium arsenide. The crystalline phase of the doped layers can be amorphous, microcrystalline, nanocrystalline, single crystalline, or polycrystalline, etc. in terms of the arrangement of the substance. The materials of the N-type doped layer 3 and the P-type doped layer 2 can be the same or different. For example, the materials of the N-type doped layer 3 and the P-type doped layer 2 can both include doped polysilicon. For another example, the material of the P-type doped layer 2 can include doped polysilicon, and the material of the N-type doped layer 3 can include at least one of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon. The P-type doped layer 2 can be obtained by in-situ doping on the surface of the silicon substrate or by deposition on the surface of the silicon substrate. The N-type doped layer 3 can also be obtained by in-situ doping on the surface of the silicon substrate or by deposition on the surface of the silicon substrate. For example, the P-type doped layer 2 can be provided on the silicon substrate by in-situ doping. For another example, the P-type doped layer 2 can be obtained by deposition on the surface of the silicon substrate (e.g., an epitaxial doped layer).

[0061] The passivation layer 3 refers to a surface passivation layer and is provided on the N-type doped layer 3 and the P-type doped layer 2. The passivation layer 3 is located on the side of the N-type doped layer 3 and the P-type doped layer 2 away from the silicon substrate 1. In the thickness direction L1 of the silicon substrate 1, the doped layers are located between the silicon substrate 1 and the passivation layer 3.

[0062] The P-type collector electrode 5 is located on the side of the P-type doped layer 2 away from the silicon substrate 1, the P-type collector electrode 5 extends into the P-type doped layer 2 through the passivation layer 3 and forms an ohmic contact with the P-type doped layer 2, and the P-type collector electrode 5 can collect carriers and conduct current. The N-type collector electrode 6 is located on the side of the N-type doped layer 3 away from the silicon substrate 1, the N-type collector electrode 6 extends into the N-type doped layer 3 through the passivation layer 3 and forms an ohmic contact with the N-type doped layer 3, and the N-type collector electrode 6 can collect carriers and conduct current.

[0063] It should be noted that, referring to Figure 1 and Figure 3 , the P-type collector electrode 5 here can include a first seed layer 51 and a first base metal layer 52, or, referring to Figure 2 and Figure 4 , the P-type collector electrode 5 here can be a single metal electrode, such as a silver electrode, etc., all within the protection scope of the present application, and the features not explicitly stated in the subsequent description of the present application are applicable to the above-mentioned P-type collector electrode 5. Referring to Figure 1 and Figure 3 , the N-type collector electrode 6 here can include a second seed layer 61 and a second base metal layer 62, or, referring to Figure 2 andFigure 4 The N-type collector electrode 6 here can be a single metal electrode, such as a silver electrode, etc., all within the protection scope of the present application, and the features not explicitly described later in the present application are applicable to the N-type collector electrode 6 described above. Referring to Figure 2 and Figure 4 When the N-type collector electrode 6 and the P-type collector electrode 5 are both single metal electrodes, their material compositions are the same or different, all within the protection scope of the present application, and the features not explicitly described later in the present application are applicable to the N-type collector electrode 6 and the P-type collector electrode 5 described above. Referring to Figure 1 and Figure 3 When the N-type collector electrode 6 here can include a second seed layer 61 and a second base metal layer 62, and the P-type collector electrode 5 can include a first seed layer 51 and a first base metal layer 52, the material compositions of the first seed layer 51 and the second seed layer 61 are the same or different, and the material compositions of the first base metal layer 52 and the second base metal layer 62 are the same or different, all within the protection scope of the present application, and the features not explicitly described later in the present application are applicable to the N-type collector electrode 6 and the P-type collector electrode 5 described above. In the present application, when the collector electrode is a single metal electrode, the composition or material of the collector electrode can be the same as or different from the composition or material of the seed layer when the collector electrode includes a seed layer and a base metal layer. For example, when the composition or material of the collector electrode is the same as that of the seed layer when the collector electrode includes a seed layer and a base metal layer, both are formed by a burn-through type paste, but since the seed layer has less paste when the collector electrode includes a seed layer and a base metal layer than when the collector electrode is a single metal electrode, the sintering time can be shorter, the heat-affected zone can be relatively smaller, and the seed layer has less paste, resulting in lower cost.

[0064] SEM in the present application refers to a scanning electron microscope, Figure 5 , Figure 6 , Figure 7 , Figure 8 (b) in each of FIGS. 1 to 8 is a P-type collector electrode, and (a) is an N-type collector electrode. Figure 5 (a) and (b) of FIGS. 1 to 8 correspond to approximately the same magnification, Figure 7 (a) and (b) of FIGS. 1 to 8 correspond to approximately the same magnification, Figure 8 (a) and (b) of FIGS. 1 to 8 correspond to approximately the same magnification, Figure 9 and Figure 10 correspond to approximately the same magnification.

[0065] Figure 5 (a) of FIG. 9 is an SEM image of an ohmic contact portion of an N-type collector electrode and an N-type doped layer, Figure 5Figure 2(b) is a SEM image of the ohmic contact part of the P-type collector electrode and the P-type doped layer of Figure 2(a). Referring to Figure 5 Figure 2(b), the ohmic contact part of the P-type collector electrode 5 and the P-type doped layer 2 includes a plurality of first metal crystals 53 (mainly located Figure 5 The first metal crystals 53 and the P-type doped layer 2 can be in direct contact with each other. The first metal crystals 53 can be located on the surface of the P-type doped layer 2 and not extend into the P-type doped layer 2. The first metal crystals 53 can extend into the P-type doped layer 2. The first metal crystals 53 can be in direct contact with the P-type collector electrode 5. The first metal crystals 53 can not be in direct contact with the P-type collector electrode 5. The first metal crystals 53 can be in direct contact with both the P-type doped layer 2 and the P-type collector electrode 5. The first metal crystals 53 can be a metal element or the like. The first metal crystals 53 can be silver crystals. The first metal crystals 53 can be the key to achieving ohmic contact between the P-type collector electrode 5 and the P-type doped layer 2.

[0066] It should be noted that the shape of the first metal crystal can be in the form of a particle, for example, can be spherical or non-spherical, and the non-spherical shape can include any one of pebble-shaped or irregular-shaped. For the spherical first metal crystal, the length of the above-mentioned first metal crystal can be the diameter of the sphere. For the non-spherical first metal crystal, the length of the above-mentioned first metal crystal can be the equivalent length, which can be understood as the size in the direction of extension. It should be noted that the measurement of the length of the first metal crystal is not limited in the present application, and can be determined by conventional methods in the art, for example, in the electrode profile, the farthest distance between the two end faces of the first metal crystal in the direction perpendicular to the width direction of the electrode.

[0067] In some possible embodiments, along the width direction of the P-type collector electrode 5, the distribution area width of the first metal crystal 53 is A1, and the direction in which A1 is located is the same as the width direction of the P-type collector electrode 5. The width direction of the P-type collector electrode 5 is perpendicular to the extension direction of the P-type collector electrode 5. The extension direction of the P-type collector electrode 5 refers to the direction of the length of the P-type collector electrode 5, and the whole P-type collector electrode 5 extends in a certain direction, and the local part can allow appropriate bending in other directions. Along the width direction of the P-type collector electrode 5, the distribution area width of the first metal crystal 53 refers to: in one P-type collector electrode 5, the size between the geometric centers of the first metal crystals 53 of the two edges at opposite ends along the width direction of the P-type collector electrode 5, or the size between the two inner boundaries of the first metal crystals 53 of the two edges at opposite ends, or the size between the two outer boundaries of the first metal crystals 53 of the two edges at opposite ends, or the size between the inner boundary of the first metal crystal 53 of one edge and the outer boundary of the first metal crystal 53 of the other edge of the first metal crystals 53 of the two edges at opposite ends; or the average value of the above-mentioned at least two types of sizes along the width direction of the P-type collector electrode 5 in the same P-type collector electrode 5. For example, Figure 5 In (b) of the above-mentioned (a), A1 is the size between the two outer boundaries of the first metal crystals 53 of the two edges at opposite ends along the width direction of the P-type collector electrode 5 in one P-type collector electrode 5.

[0068] Referring to Figure 5 In (a) of the above-mentioned (a), the ohmic contact part of the N-type collector electrode 6 and the N-type doped layer 3 includes a plurality of second metal crystals 63 (mainly located Figure 5The second metal crystal 63 can further improve the electrical connection effect. The distribution of the second metal crystal 63 and the N-type doped layer 3 can include at least the following cases: 1, the second metal crystal 63 and the N-type doped layer 3 are not in direct contact; 2, the second metal crystal 63 is located on the surface of the N-type doped layer 3 and does not extend into the N-type doped layer 3; 3, the second metal crystal in the N-type collector electrode extends into the N-type doped layer 3. The distribution of the second metal crystal 63 and the N-type collector electrode (which can refer to the single metal electrode mentioned above, or the seed layer of the N-type collector electrode) can include at least the following cases: 1, the second metal crystal in the N-type collector electrode is in direct contact with the surface of the N-type collector electrode; 2, the second metal crystal in the N-type collector electrode is not in direct contact with the N-type collector electrode. The direct positional relationship between the distribution of the second metal crystal and the N-type doped layer and the N-type collector electrode can be any combination of the above two distribution positions. The second metal crystal can be a metal element, and the composition of the second metal crystal is related to the composition of the ohmic contact part of the N-type collector electrode 6 and the N-type doped layer 3. For example, the ohmic contact part of the N-type collector electrode 6 and the N-type doped layer 3 contains silver elements, and the second metal crystal here can be silver. The formation reason, composition and shape of the second metal crystal are the same as or similar to those of the first metal crystal, and will not be repeated here. It should be noted that the materials or compositions of the first metal crystal 53 and the second metal crystal 63 can be the same or different, and are within the protection scope of the present application.

[0069] The distribution area width of the second metal crystal 63 along the width direction of the N-type collector electrode 6 is A2. The direction of A2 is the same as the width direction of the N-type collector electrode 6, and the width direction of the N-type collector electrode 6 is the same as or parallel to the width direction of the P-type collector electrode 5. The determination method of the distribution area width of the second metal crystal 63 along the width direction of the N-type collector electrode 6 is the same as or similar to that of the distribution area width of the first metal crystal 53 along the width direction of the P-type collector electrode 5, and will not be repeated here.

[0070] In the present application, reference is made to Figure 5A1>A2. Specifically, first, in the solar cell, the doping concentration of the P-type doped layer 2 is usually less than that of the N-type doped layer 3, along the width direction of the P-type collecting electrode 5, the distribution area width A1 of the first metal crystal 53 is larger, the coverage of the first metal crystal 53 in the P-type collecting electrode 5 is larger, and the coverage of the ohmic contact between the P-type collecting electrode 5 and the P-type doped layer 2 is larger. In this way, the electrical connection effect of the P-type collecting electrode 5 and the P-type doped layer 2 is better, and the collection effect of the current or carrier in the P-type doped layer 2 is improved, so as to offset the influence of the lower doping concentration in the P-type doped layer 2, and the difference between the two doped layers is reduced, and the performance of the battery is improved; second, in the solar cell, the bonding force and pulling force between the P-type collecting electrode 5 and the P-type doped layer 2 is usually less than that between the N-type collecting electrode 6 and the N-type doped layer 3, so the risk of pulling off at the P-type collecting electrode 5 is easy to exist, and the coverage of the first metal crystal 53 in the P-type collecting electrode 5 is larger, the coverage of the ohmic contact between the P-type collecting electrode 5 and the P-type doped layer 2 is larger, the bonding force and pulling force between the P-type collecting electrode 5 and the P-type doped layer 2 is improved, and the difference between the bonding force and pulling force between the P-type collecting electrode 5 and the P-type doped layer 2 and the bonding force and pulling force between the N-type collecting electrode 6 and the N-type doped layer 3 is reduced, so as to reduce the risk of pulling off due to insufficient bonding force of the P-type collecting electrode connected with the P-type doped layer; third, the coverage of the first metal crystal 53 in the P-type collecting electrode 5 is larger, which can effectively reduce the contact resistance corresponding to the P-type collecting electrode 5, and further reduce the difference between the contact resistances corresponding to the P-type collecting electrode and the N-type collecting electrode, and improve the performance of the battery.

[0071] It should be noted that the specific difference between A1 and A2 is not limited, and can be set according to the need for balancing the difference between the carriers or currents in the two doped layers in the solar cell.

[0072] For example, the ratio of the doping concentration of the N-type doped layer to the doping concentration of the P-type doped layer is in the range of 1 to 1E5.

[0073] In some possible embodiments, with reference to Figure 5, along the width direction of the P-type collecting electrode 5, the distribution density of the first metal crystal 53 in the distribution area of the first metal crystal 53 is B1. Along the width direction of the N-type collecting electrode 6, the distribution density of the second metal crystal 63 in the distribution area of the second metal crystal 63 is B2. Wherein, B1 < B2. The distribution density B1 of the first metal crystal 53 in the distribution area of the first metal crystal 53 along the width direction of the P-type collecting electrode 5 can refer to the ratio of the number of the first metal crystal 53 to the width A1 of the distribution area of the first metal crystal 53 along the width direction of the P-type collecting electrode 5. The determination method of the distribution density B2 of the second metal crystal 63 in the distribution area of the second metal crystal 63 along the width direction of the N-type collecting electrode 6 is the same as or similar to the determination method of B1, and will not be repeated here. B1 can reflect the density of the first metal crystal 53 in the distribution area of the first metal crystal 53 along the width direction of the P-type collecting electrode 5. If B1 is smaller, the first metal crystal 53 in the distribution area of the first metal crystal 53 along the width direction of the P-type collecting electrode 5 is more sparse. If B1 is larger, the first metal crystal 53 is more densely distributed in the distribution area. In this application, B1 is smaller, the first metal crystal 53 in the distribution area of the first metal crystal 53 is more sparse, the transport or diffusion path of the carriers at each position is approximately the same and is relatively short, the recombination probability is relatively small, B2 is larger, the second metal crystal 63 in the distribution area of the second metal crystal 63 is more dense, the transport or diffusion path of the carriers at some positions is relatively far, resulting in a relatively large recombination probability, thereby reducing the difference in carriers or current between the two doped layers and improving the performance of the battery; at the same time, the bonding force and pulling force between the P-type collecting electrode 5 and the P-type doped layer 2 are improved, and the difference between the bonding force and pulling force between the P-type collecting electrode 5 and the P-type doped layer 2 and the bonding force and pulling force between the N-type collecting electrode 6 and the N-type doped layer 3 is reduced, so as to reduce the risk of pulling off due to insufficient bonding force of the P-type collecting electrode electrically connected to the P-type doped layer.

[0074] It should be noted that the specific difference between B1 and B2 is not limited, and can be set according to the need for balancing the difference in carriers or current between the two doped layers in the solar cell.

[0075] In some possible embodiments, with reference to Figure 5, the number of the first metal crystals 53 along the width direction of the P-type collecting electrode 5 is C1, and the number of the second metal crystals 63 along the width direction of the N-type collecting electrode 6 is C2, and C1>C2. When the number of the first metal crystals 53 along the width direction of the P-type collecting electrode 5 is C1, the number of the first metal crystals 53 forming the ohmic contact points in the P-type collecting electrode 5 is more, the transmission channel between the P-type collecting electrode 5 and the P-type doped layer 2 is more, the electrical connection effect between the P-type collecting electrode 5 and the P-type doped layer 2 is better, and the collection effect of the current or the carrier in the P-type doped layer 2 is improved, so as to offset the influence of the lower doping concentration in the P-type doped layer 2, and the difference between the carriers or the current in the two doped layers is reduced, and the performance of the battery is improved. At the same time, the bonding force and the pulling force between the P-type collecting electrode 5 and the P-type doped layer 2 are improved, and the difference between the bonding force and the pulling force between the P-type collecting electrode 5 and the P-type doped layer 2 and the bonding force and the pulling force between the N-type collecting electrode 6 and the N-type doped layer 3 is reduced, so as to reduce the risk of pulling off caused by the insufficient bonding force of the P-type collecting electrode electrically connected with the P-type doped layer.

[0076] It should be noted that the specific difference between C1 and C2 is not limited, and can be set according to the need for balancing the difference between the carriers or the current in the two doped layers in the solar cell.

[0077] It can be understood that the number of the first metal crystals 53 and the second metal crystals 63 can be the number of the metal crystals obtained in the SEM picture field along a certain cross section perpendicular to the extension direction of the collecting electrode. For example, a single region with the same area size is taken, and then the metal crystals observed in the region are counted, that is, the number of the metal crystals. Or, multiple regions with the same area size are taken, and then the metal crystals observed in each region are counted, and then the average value of the number of the metal crystals in the multiple regions is calculated, that is, the number of the metal crystals. Or, a region below the electrode to be tested is taken, and then the number of the metal crystals observed in the region is calculated by using the image processing software.

[0078] In some possible embodiments, referring to Figure 5, the size of the first metal crystal 53 is greater than the size of the second metal crystal 63, which can include: in the solar cell, the size of the first metal crystal 53 with the largest size among all the first metal crystals 53 is greater than the size of the second metal crystal 63 with the largest size among all the second metal crystals 63, or, in the solar cell, the proportion of the number of the first metal crystals 53 with a size greater than a set size is greater than the proportion of the number of the second metal crystals 63 with a size greater than the set size, or, in the solar cell, the average size of two or more first metal crystals 53 is greater than the average size of two or more second metal crystals 63, then the size of the ohmic contact point formed by the first metal crystal 53 in the P-type collecting electrode 5 is larger, the conductive channel formed by the contact position of the P-type collecting electrode 5 and the P-type doped layer 2 is larger, the electrical connection effect of the P-type collecting electrode 5 and the P-type doped layer 2 is better, thereby improving the collection effect of the current or carrier in the P-type doped layer 2, to offset the influence of the lower doping concentration in the P-type doped layer 2, thereby reducing the difference in carriers or current between the two doped layers and improving the performance of the battery; at the same time, the bonding force and pulling force between the P-type collecting electrode 5 and the P-type doped layer 2 are improved, and the difference between the bonding force and pulling force between the P-type collecting electrode 5 and the P-type doped layer 2 and the bonding force and pulling force between the N-type collecting electrode 6 and the N-type doped layer 3 is reduced, to reduce the risk of pulling off due to insufficient bonding force of the P-type collecting electrode electrically connected to the P-type doped layer. The size here can include at least one of length, width, and height, and for a first metal crystal, the largest size of the first metal crystal can refer to the largest size of at least one of the length, width, and height of the first metal crystal. The definition of the largest size of the second metal crystal is similar or the same, and to avoid repetition, it will not be described here.

[0079] For example, in the same solar cell: the depth of the second metal crystal 63 is 40-150 nm, the length or width of the second metal crystal 63 is 40-400 nm; the length or width of the first metal crystal 53 is 40-500 nm, and the depth of the first metal crystal is 60-200 nm. The direction of the depth here can be parallel to the height direction of the photovoltaic module. For example, the depth of the second metal crystal 63 can be 40 nm, 50 nm, 55 nm, 60 nm, 70 nm, 75 nm, 80 nm, 90 nm, 95 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm. For example, the length or width of the second metal crystal 63 can be 40 nm, 50 nm, 60 nm, 70 nm, 75 nm, 80 nm, 90 nm, 100 nm, 101 nm, 110 nm, 120 nm, 130 nm, 135 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm. For example, the depth of the first metal crystal 53 can be 60 nm, 70 nm, 75 nm, 80 nm, 90 nm, 100 nm, 101 nm, 110 nm, 120 nm, 130 nm, 135 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm. For another example, the length or width of the first metal crystal 53 can be 40 nm, 50 nm, 60 nm, 70 nm, 75 nm, 80 nm, 90 nm, 100 nm, 101 nm, 110 nm, 120 nm, 130 nm, 135 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 420 nm, 450 nm, 500 nm. It should be noted that in the process of selecting the size of the metal crystal, it is necessary to ensure that the size of the first metal crystal 53 is larger than the size of the second metal crystal 63 in the photovoltaic module or solar cell. The size of the metal crystal is related to the contact effect and diffusion. If the size of the metal crystal W2 is too large, the metal crystal may have the risk of diffusing into the silicon substrate. Therefore, the metal crystal in the above range basically does not diffuse into the silicon substrate, and the contact effect of the collector electrode and the doped silicon layer is good, and the conductivity of the collector electrode is good.

[0080] In some possible embodiments, referring to Figure 6 (b), the depth of the first metal crystal 53 extending into the P-type doped layer 2 is D1, and referring to Figure 6of (a), the second metal crystal 63 extends into the N-type doped layer 3 by a depth D2, and reference is made to Table 1 and Table 2 below, wherein D1>D2. The first metal crystal 53 extends into the P-type doped layer 2 by a depth D1, which is deeper, so that the area of the ohmic contact between the first metal crystal 53 and the P-type doped layer 2 in the P-type collector electrode 5 is larger, and the electrical connection effect between the P-type collector electrode 5 and the P-type doped layer 2 is better, thereby improving the collection effect of the current or the carrier in the P-type doped layer 2, offsetting the influence of the lower doping concentration in the P-type doped layer 2, thereby reducing the difference in the carrier or the current between the two doped layers, and improving the performance of the solar cell; at the same time, the bonding force and the pulling force between the P-type collector electrode 5 and the P-type doped layer 2 are improved, and the difference between the bonding force and the pulling force between the P-type collector electrode 5 and the P-type doped layer 2 and the bonding force and the pulling force between the N-type collector electrode 6 and the N-type doped layer 3 is reduced, so as to reduce the risk of pulling off due to insufficient bonding force of the P-type collector electrode electrically connected to the P-type doped layer.

[0081] For example, reference is made to Table 1 below, which shows the specific size and corresponding probability of the depth D1 at which the first metal crystal 53 extends into the P-type doped layer 2 and the depth D2 at which the second metal crystal 63 extends into the N-type doped layer 3 in the solar cell when the paste of the N-type collector electrode 6 and the paste of the P-type collector electrode 5 are the same.

[0082] Table 1: Comparison table of D1 and D2 when the paste is the same

[0083]

[0084] From Table 1, it can be seen that when the paste of the N-type collector electrode 6 and the paste of the P-type collector electrode 5 are the same, the probability that the depth at which the first metal crystal 53 extends into the P-type doped layer 2 is greater than or equal to 100.2 nm accounts for 77.43%, while the probability that the depth at which the second metal crystal 63 extends into the N-type doped layer 3 is greater than or equal to 78 nm accounts for only 66.67%; in addition, in the solar cell, the maximum depth at which the first metal crystal 53 extends into the P-type doped layer 2 reaches 180.2 nm, while the maximum depth at which the second metal crystal 63 extends into the N-type doped layer 3 reaches only 138 nm; therefore, the depth at which the first metal crystal 53 extends into the P-type doped layer 2 is greater than the depth at which the second metal crystal 63 extends into the N-type doped layer 3, and at a greater depth, the corresponding probability of the first metal crystal 53 is greater, so that in the solar cell, D1>D2.

[0085] For example, referring to Table 2 below, which shows the specific sizes of the depth Dl at which the first metal crystal 53 extends into the P-type doped layer 2 and the depth D2 at which the second metal crystal 63 extends into the N-type doped layer 3 in the case where the paste of the N-type collecting electrode 6 and the paste of the P-type collecting electrode 5 are different in the solar cell.

[0086] Table 2: Comparison table of Dl and D2 in the case where the pastes are different

[0087] D1 (nm) of the first metal crystal D2 (nm) of the second metal crystal 146.6 37.38 73.3 59.11 93.27 47.29 80.39 75.67

[0088] Table 2 is a table of parameters measured from 8 same-area regions selected from the same solar cell, 4 of which contain the first metal crystal and the other 4 of which contain the second metal crystal. As shown in Table 2, in the case where the paste of the N-type collecting electrode 6 and the paste of the P-type collecting electrode 5 are different, the depth at which the first metal crystal 53 extends into the P-type doped layer 2 in the 4 same-area regions is greater than the depth at which the second metal crystal 63 extends into the N-type doped layer 3 in the 4 same-area regions. In addition, the maximum depth at which the first metal crystal 53 extends into the P-type doped layer 2 in the solar cell reaches 146.6 nm, while the maximum depth at which the second metal crystal 63 extends into the N-type doped layer 3 reaches only 75.67 nm; therefore, Dl>D2 in the solar cell.

[0089] It should be noted that the difference between Dl and D2 can be greater in the case where the paste of the N-type collecting electrode 6 and the paste of the P-type collecting electrode 5 are the same, and the difference between Dl and D2 can be smaller in the case where the paste of the N-type collecting electrode and the paste of the P-type collecting electrode 5 are different. For example, in the case where the N-type collecting electrode 6 includes the second seed layer 61 and the second base metal layer 62, and the P-type collecting electrode 5 includes the first seed layer 51 and the first base metal layer 52. In the case where the paste of the first seed layer 51 and the second seed layer 61 is the same, the difference between Dl and D2 can be greater, and in the case where the paste of the first seed layer 51 and the second seed layer 61 is different, the difference between Dl and D2 can be greater (for example, Dl can be 20-230 nm and D2 can be 15-150 nm in the solar cell). Alternatively, in the case where the N-type collecting electrode 6 and the P-type collecting electrode 5 are both single-metal electrodes, the difference between Dl and D2 can be greater in the case where the paste of the N-type collecting electrode 6 and the paste of the P-type collecting electrode 5 are the same, and the difference between Dl and D2 can be smaller in the case where the paste of the N-type collecting electrode 6 and the paste of the P-type collecting electrode 5 are different. The specific difference between Dl and D2 is not limited.

[0090] Referring to Figure 6The determination manner of D1 can be that, in the same area region of the solar cell, the maximum depth of all the first metal crystals 53 extending into the P-type doped layer; or, D1 can be the average depth of the first metal crystals 53 extending into the P-type doped layer in two or more same area regions of the solar cell. The determination manner of D1 is the same as or similar to the determination manner of D2, and for the sake of brevity, the same will not be described again, and both can be limited in the same area region. The same area region can be selected from the region containing the first metal crystals in the solar cell, or the region containing the second metal crystals in the solar cell, and the area here can be the area of the surface perpendicular to the thickness direction of the solar cell.

[0091] In some possible embodiments, referring to Figure 5 , the ratio of the number of the first metal crystals 53 extending into the P-type doped layer 2 to the total number of the first metal crystals 53 is greater than the ratio of the number of the second metal crystals 63 extending into the N-type doped layer 3 to the total number of the second metal crystals 63, then the number of the first metal crystals 53 forming ohmic contact points in the P-type collecting electrode 5 is greater, the conductive channels formed at the contact position of the P-type collecting electrode 5 and the P-type doped layer 2 are more, and the electrical connection effect of the P-type collecting electrode 5 and the P-type doped layer 2 is better, thereby improving the collection effect of the current or carriers in the P-type doped layer 2 to offset the influence of the lower doping concentration in the P-type doped layer 2, thereby reducing the difference between the carriers or current in the two doped layers and improving the performance of the solar cell; at the same time, the bonding force and pulling force between the P-type collecting electrode 5 and the P-type doped layer 2 are improved, and the difference between the bonding force and pulling force between the P-type collecting electrode 5 and the P-type doped layer 2 and the bonding force and pulling force between the N-type collecting electrode 6 and the N-type doped layer 3 is reduced, so as to reduce the risk of pulling off due to insufficient bonding force of the P-type collecting electrode electrically connected with the P-type doped layer.

[0092] The comparison between the ratio of the number of the first metal crystals 53 extending into the P-type doped layer 2 to the total number of the first metal crystals 53 and the ratio of the number of the second metal crystals 63 extending into the N-type doped layer 3 to the total number of the second metal crystals 63 can also be limited in the same area region, and the selection of the same area region is similar to the selection of the same area region described above, and for the sake of brevity, the same will not be described again.

[0093] In some possible embodiments, referring to Figure 6 (b), the side surface of the P-type doped layer 2 close to the silicon substrate is the lower surface of the P-type doped layer 2, the first metal crystal 53 at the position with the smallest vertical distance from the lower surface of the P-type doped layer 2 has a vertical distance E1 from the lower surface of the P-type doped layer 2, and referring to Figure 6The lower surface of the N-type doped layer 3 is close to the side surface of the silicon substrate, the second metal crystal 63 at the position with the minimum vertical distance from the lower surface of the N-type doped layer 3 has a vertical distance E2 from the lower surface of the N-type doped layer 3, E1 < E2, and E1 is smaller, indicating that the first metal crystal 53 is closer to the silicon substrate, the distance of the carriers from the silicon substrate to the first metal crystal 53 is shorter, and the current or carrier collection effect of the P-type collector electrode 5 is better, so as to offset the influence of the lower doping concentration in the P-type doped layer 2, and further reduce the difference in the carriers or current in the two doped layers, and improve the performance of the battery.

[0094] In some possible embodiments, referring to Figure 6 , the ratio of the depth of the extension of the first metal crystal 53 into the P-type doped layer 2 to the thickness of the P-type doped layer 2 is F1, the thickness of the P-type doped layer 2 is H1, F1 = D1 / H1, the ratio of the depth of the extension of the second metal crystal 63 into the N-type doped layer 3 to the thickness of the N-type doped layer 3 is F2, the thickness of the N-type doped layer 3 is H2, F2 = D2 / H2, and F1 > F2. Specifically, F1 can represent the relative depth of the extension of the first metal crystal 53 into the P-type doped layer, and F1 is larger, indicating that the relative depth of the extension of the first metal crystal 53 into the P-type doped layer is larger, the ohmic contact formed by the first metal crystal 53 in the P-type collector electrode 5 is more sufficient, the electrical connection effect of the P-type collector electrode 5 and the P-type doped layer 2 is better, and the current or carrier collection effect in the P-type doped layer 2 is further improved, so as to offset the influence of the lower doping concentration in the P-type doped layer 2, and further reduce the difference in the carriers or current in the two doped layers, and improve the performance of the battery; at the same time, the bonding force and pulling force between the P-type collector electrode 5 and the P-type doped layer 2 are improved, and the difference between the bonding force and pulling force between the P-type collector electrode 5 and the P-type doped layer 2 and the bonding force and pulling force between the N-type collector electrode 6 and the N-type doped layer 3 is reduced, so as to reduce the risk of pulling off due to insufficient bonding force of the P-type collector electrode electrically connected to the P-type doped layer.

[0095] In some possible embodiments, referring to Figure 1 and Figure 3, the P-type collecting electrode 5 comprises a first seed layer 51 and a first base metal layer 52, the first seed layer 51 is electrically connected with the P-type doped layer 2 through the passivation layer 4, and the first base metal layer 52 covers the first seed layer 51 and is electrically connected with the P-type doped layer 2 through the first seed layer 51. The first base metal layer 52 replaces the noble metal, which can reduce the cost of the battery; secondly, compared with the noble metal, some base metals in the first base metal layer 52 are more likely to diffuse, and the first seed layer 51 is closer to the silicon substrate, which can block the inward diffusion of the base metals in the first base metal layer 52 and can greatly avoid the problem of recombination caused by the further diffusion of the metal elements in the first base metal layer 52 to the inside of the silicon substrate 1. In summary, the application not only reduces the cost of the battery, but also improves the conductivity of the electrode structure and reduces the recombination. Referring to Figure 7 (b), the first base metal layer 52 comprises a plurality of metal particles, and the first seed layer 51 comprises a plurality of first metal crystals 53.

[0096] In some possible embodiments, referring to Figure 1 and Figure 3 the N-type collecting electrode 6 comprises a second seed layer 61 and a second base metal layer 62, the second seed layer 61 is electrically connected with the N-type doped layer 3 through the passivation layer 4, and the second base metal layer 62 covers the second seed layer 61 and is electrically connected with the N-type doped layer 3 through the second seed layer 61. First, the second base metal layer 62 replaces the noble metal, which can reduce the cost of the battery; secondly, compared with the noble metal, some base metals in the second base metal layer 62 are more likely to diffuse, and the second seed layer 61 is closer to the silicon substrate, which can block the inward diffusion of the base metals in the second base metal layer 62 and can greatly avoid the problem of recombination caused by the further diffusion of the metal elements in the second base metal layer 62 to the inside of the silicon substrate 1. In summary, the application not only reduces the cost of the battery, but also improves the conductivity of the electrode structure and reduces the recombination. Referring to Figure 7 (a), the second base metal layer 62 comprises a plurality of metal particles, and the second seed layer 61 comprises a plurality of second metal crystals 63.

[0097] It should be noted that the mass percentage of the base metal elements in the first base metal layer 52 can be greater than 50%. The mass percentage of the base metal elements in the second base metal layer 62 can be greater than 50%.

[0098] The specific material of the first seed layer 51 and the second seed layer 52 is not limited. In some possible embodiments, the material of the first seed layer 51 can be selected from at least one of aluminum (Al), iron (Fe), magnesium (Mg), silver (Ag), gold (Au), 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), titanium boride (TiB x ), tantalum nitride (TaN x ), tungsten nitride (WN x ), titanium nitride (TiN x ), titanium tungsten alloy (TiW x ), titanium silicon compound (TiSi x ), titanium silicon nitride (TiSiN), tantalum silicon nitride (TaSiN x ), nickel vanadium (NiV), and hexagonal boron nitride (WBN). The first seed layer of the above-mentioned materials is easy to set and easy to form a honeycomb structure. For example, the first seed layer 51 is a silver layer, so that the ohmic contact can be achieved by high-temperature burning through the passivation layer and the P-type doped layer. It should be noted that the material of the second seed layer 61 can refer to the material of the first seed layer, and the two can be the same or different, and details are not repeated here.

[0099] The specific material of the first base metal layer 52 and the second base metal layer 62 is not limited. In some possible embodiments, the material of the first base metal layer 52 is selected from at least one of copper (Cu), nickel (Ni), chromium (Cr), lead (Pb), aluminum (Al), and silver-coated copper. Firstly, the above-mentioned materials have good conductivity. Secondly, the above-mentioned materials have low cost, which can reduce the cost of the electrode. Thirdly, the above-mentioned materials can be formed by low-temperature process, which avoids the penetration of the passivation layer to the silicon substrate to reduce the recombination, and avoids the introduction of heat into the solar cell. It should be noted that the material of the second base metal layer can refer to the material of the first base metal layer, and the material of the second base metal layer and the material of the first base metal layer can be the same or different in the same cell, and details are not repeated here.

[0100] It should be noted that the materials of the first seed layer and the first base metal layer are different in the P-type collector electrode, and the materials of the second seed layer and the second base metal layer are different in the N-type collector electrode.

[0101] It should be noted that a tunneling layer 7 can be arranged between the N-type doped layer and the silicon substrate, and between the P-type doped layer and the silicon substrate, and the tunneling layer 7 can be a tunneling oxide layer, etc., which is not limited in particular. The N-type and P-type collector electrodes can be arranged in any manner, for example, by printing. The first seed layer and the first base metal layer can be arranged in any manner. For example, the first seed layer and the first base metal layer can be arranged by printing, or the first seed layer can be prepared by electroplating or evaporation, etc. For another example, the first seed layer precursor is printed first, then the first seed layer is obtained by sintering, then the first base metal layer precursor is printed on the first seed layer, and then the P-type collector electrode is obtained by drying. The preparation process of the N-type collector electrode can be the same as or similar to the above, and thus will not be described again to avoid repetition.

[0102] It should be noted that the first seed layer and the second seed layer can be formed simultaneously, or the order of formation of the two can be different. The slurry used for the first seed layer and the second seed layer can be the same or different, which is within the protection scope of the present application.

[0103] In some possible embodiments, in the case where the slurry used for the first seed layer 51 and the second seed layer 61 is different, for double-sided solar cells (such as Figure 1 , Figure 2 ), back contact solar cells (such as Figure 3 and Figure 4 ), the first seed layer and the second seed layer can be arranged in any manner, for example, by printing. The first seed layer and the second seed layer can be arranged in any manner. For example, the first seed layer and the second seed layer can be arranged by printing, or the first seed layer can be prepared by electroplating or evaporation, etc. For another example, the first seed layer precursor is printed first, then the first seed layer is obtained by sintering, then the first base metal layer precursor is printed on the first seed layer, and then the P-type collector electrode is obtained by drying. The preparation process of the N-type collector electrode can be the same as or similar to the above, and thus will not be described again to avoid repetition. Figure 3 , Figure 7 , Figure 9 and Figure 10The height k1 of the first seed layer 51 is greater than the height k2 of the second seed layer 61. The height k1 of the first seed layer 51 electrically connected to the P-type doped layer is higher, thereby further enhancing the bonding force and pulling force between the first seed layer electrically connected to the P-type doped layer and the first base metal layer electrically connected to the P-type doped layer, and also enhancing the bonding force of the P-type collector electrode electrically connected to the P-type doped layer and the electrical connector, reducing the difference in the bonding force and pulling force between the P-type collector electrode 5 and the P-type doped layer 2, and the difference in the bonding force and pulling force between the N-type collector electrode 6 and the N-type doped layer 3, to reduce the risk of pulling off due to the imbalance of the bonding force of the P-type collector electrode electrically connected to the P-type doped layer. In addition, the current collection capability of the region where the P-type doped layer is located is also improved, to reduce the current difference between the P-type doped layer and the N-type doped layer, avoiding the case of local current loss. That is, a higher first seed layer is provided on the P-type doped layer with a higher resistivity. Such a setting can further improve the conductivity of the corresponding region of the silicon substrate and the P-type doped layer, reduce the contact resistivity, better balance the ability of the conductive carriers between the N region and the P region, and thereby reduce the impact on the electrical performance due to the imbalance of the doping concentration of the P-type doped layer. It should be noted that the difference between the heights of the two is not specifically limited. Here, in the case of a bifacial solar cell, the P-type doped layer 2 can be located on the front surface of the silicon substrate, and the N-type doped layer 3 can be located on the back surface of the silicon substrate, or the P-type doped layer 2 can be located on the back surface of the silicon substrate, and the N-type doped layer 3 can be located on the front surface of the silicon substrate 1. Both of the above cases are within the scope of the present application. Here, the height of the first seed layer can be compared with the height of the second seed layer in the entire solar cell, and the height k1 of the first seed layer is greater than the height k2 of the second seed layer. In some possible embodiments, in the case where the first seed layer 51 and the second seed layer 61 use different pastes, the height k1 of the first seed layer electrically connected to the P-type doped layer is greater than the height k2 of the second seed layer electrically connected to the N-type doped layer in the same region of the solar cell. Here, the comparison of the heights of the above seed layers is made in the same region of the solar cell, and the heights of the two seed layers are compared. The division of the region is not limited. For example, the region can include: a middle region located in the middle of the surface of the solar cell, an edge region located at the edge of the surface of the solar cell, and the middle region is closer to the center of the solar cell than the edge region.

[0104] In some possible embodiments, in the case where the first seed layer 51 and the second seed layer 61 use different pastes, for a bifacial solar cell, a back contact solar cell, with reference to Figure 3 、 Figure 7 、 Figure 9 and Figure 10, the width m1 of the first seed layer electrically connected with the P-type doped layer is greater than the width m2 of the second seed layer electrically connected with the N-type doped layer in the direction perpendicular to the first seed layer, the first seed layer has stronger lateral transmission capacity, and the electrical performance caused by the imbalance of the doping concentration of the P-type doped layer is reduced. In addition, the width of the seed layer electrically connected with the P-type doped layer is greater, and the bonding force and pulling force between the seed layer electrically connected with the P-type doped layer and the base metal layer electrically connected with the P-type doped layer are further enhanced, the bonding force between the electrode structure electrically connected with the P-type doped layer and the electrical connector is also enhanced, and the difference between the bonding force and the pulling force between the P-type collector electrode 5 and the P-type doped layer 2 and between the N-type collector electrode 6 and the N-type doped layer 3 is reduced, so as to reduce the risk of pulling off caused by the imbalance of the bonding force of the electrode structure electrically connected with the P-type doped layer. In addition, the current collection capacity of the region where the P-type doped layer is located is also improved, and the electrical performance caused by the imbalance of the doping concentration of the P-type doped layer is reduced. It should be noted that the difference between the widths of the two is not specifically limited. Here, in the case that the solar cell is a bifacial solar cell: the P-type doped layer can be located on the front surface of the silicon substrate, and the N-type doped layer can be located on the back surface of the silicon substrate, or the P-type doped layer can be located on the back surface of the silicon substrate, and the N-type doped layer can be located on the front surface of the silicon substrate, both of which are within the protection scope of the present application. Here, the widths of the two seed layers can be compared in the entire solar cell, and the width of the first seed layer is greater than that of the second seed layer.

[0105] In some possible embodiments, in the case that the slurry used by the first seed layer 51 and the second seed layer 61 is different, the width of the first seed layer electrically connected with the P-type doped layer can be greater than the width of the second seed layer electrically connected with the N-type doped layer in the same region of the solar cell. The same region is described above, and details are not described here again to avoid repetition.

[0106] In some possible embodiments, in the case that the slurry used by the first seed layer 51 and the second seed layer 61 is the same or the first seed layer 51 and the second seed layer 61 are integrally formed, for a bifacial solar cell (such as Figure 1 、 Figure 2 ), a back contact solar cell (such as Figure 3 and Figure 4 ), the height of the first seed layer 51 is substantially the same as the height of the second seed layer 61, and the preparation process of the two is simple. The heights of the two seed layers can be compared in the entire solar cell, and the height of the first seed layer is substantially the same as that of the second seed layer. The substantially same here can include: the heights of the two are completely equal, or the absolute value of the difference between the two is less than or equal to 5% of the smaller one of the heights of the two.

[0107] It should be noted that the height of the first seed layer can refer to the maximum dimension in the thickness direction of the silicon substrate 1 of the portion of the first seed layer on the side of the P-type doped layer 2 away from the silicon substrate 1, or the height of the first seed layer can refer to the average of the dimensions at two or more positions in the thickness direction of the silicon substrate 1 of the portion of the first seed layer on the side of the P-type doped layer 2 away from the silicon substrate 1. The determination of the height mentioned in this application can be similar or the same, and will not be repeated here.

[0108] In some possible embodiments, the slurry used for the first seed layer 51 and the second seed layer 61 is the same, or the first seed layer 51 and the second seed layer 61 are integrally formed, in which case, for a bifacial solar cell (such as Figure 1 、 Figure 2 ), a back contact solar cell (such as Figure 3 and Figure 4 ), the width of the first seed layer electrically connected to the P-type doped layer is substantially the same as the width of the second seed layer electrically connected to the N-type doped layer in the direction perpendicular to the first seed layer. The preparation process of both is simple. Here, the width of the two seed layers can be compared in the entire solar cell, and the width of the first seed layer is greater than the width of the second seed layer. Substantially the same here can include that the widths of the two are exactly the same, or the absolute value of the difference between the two is less than or equal to 5% of the smaller one of the widths of the two.

[0109] It should be noted that the width of the first seed layer can refer to the maximum dimension in the direction perpendicular to the extension direction of the portion of the first seed layer on the side of the P-type doped layer 2 away from the silicon substrate 1, or the width of the first seed layer can refer to the average of the dimensions at two or more positions in the direction perpendicular to the extension direction of the portion of the first seed layer on the side of the P-type doped layer 2 away from the silicon substrate 1. The determination of the width mentioned in this application can be similar or the same, and will not be repeated here.

[0110] In some possible embodiments, the P-type collector electrode is a single metal electrode, the N-type collector electrode is a single metal electrode, the slurry used for the first seed layer 51 and the second seed layer 61 is the same, or the first seed layer 51 and the second seed layer 61 can be integrally formed, or the slurry used for the first seed layer 51 and the second seed layer 61 is different, in which case, for a bifacial solar cell (such as Figure 1 、 Figure 2 ), a back contact solar cell (such as Figure 3 and Figure 4 ), the width of the first seed layer electrically connected to the P-type doped layer is substantially the same as the width of the second seed layer electrically connected to the N-type doped layer in the direction perpendicular to the first seed layer. The preparation process of both is simple. Here, the width of the two seed layers can be compared in the entire solar cell, and the width of the first seed layer is greater than the width of the second seed layer. Substantially the same here can include that the widths of the two are exactly the same, or the absolute value of the difference between the two is less than or equal to 5% of the smaller one of the widths of the two. Figure 2 、 Figure 8, the height q1 of the P-type collecting electrode is less than the height q2 of the N-type collecting electrode, which is compatible with the preparation process of the N-type doped layer and the P-type doped layer. Here, the height of the two collecting electrodes can also be compared in the entire solar cell or in the same region, and the height q1 of the P-type collecting electrode is less than the height q2 of the N-type collecting electrode. In addition, for the back contact solar cell, the surface of the N-type doped layer away from the silicon substrate is usually lower than the surface of the P-type doped layer away from the silicon substrate, and here the height q2 of the N-type collecting electrode is higher, which is beneficial to reducing the height difference between the surface of the N-type collecting electrode away from the silicon substrate and the surface of the P-type collecting electrode away from the silicon substrate, and in the subsequent process of printing conductive glue on the surface of the N-type collecting electrode away from the silicon substrate and the surface of the P-type collecting electrode away from the silicon substrate, the process problem of affecting the module caused by the fracture of the conductive glue due to the too large height difference between the two surfaces is avoided, so in the present application, the conductive glue is not easy to break, and the performance of the photovoltaic module is better. In addition, the height q2 of the N-type collecting electrode is larger, which can also bring the beneficial effect of small line resistance.

[0111] In some possible embodiments, the P-type collecting electrode is a single metal electrode, the N-type collecting electrode is a single metal electrode, and the paste used for the first seed layer 51 and the second seed layer 61 is the same or different. For the bifacial solar cell (such as Figure 1 、 Figure 2 ), the back contact solar cell (such as Figure 3 and Figure 4 ), referring to Figure 2 、 Figure 8 , the width s1 of the P-type collecting electrode is less than the width s2 of the N-type collecting electrode, which increases the effective contact area of the N-type collecting electrode and the N-type doped layer, reduces the diffusion length of electrons, reduces the recombination, and is compatible with the preparation process of the N-type doped layer and the P-type doped layer. Here, the width of the two collecting electrodes can also be compared in the entire solar cell or in the same region, and the width s1 of the P-type collecting electrode is less than the width s2 of the N-type collecting electrode.

[0112] In some possible embodiments, the paste used for the first seed layer 51 and the second seed layer 61 is the same or different. For the bifacial solar cell and the back contact solar cell, referring to Figure 5 、 Figure 7 、 Figure 9 and Figure 10, the first seed layer is a honeycomb structure including a plurality of holes, and the first base metal layer includes a plurality of metal particles, in the P-type collecting electrode, at least part of the metal particles are partially filled in the honeycomb structure, that is, the first base metal layer wraps the first seed layer, or in other words, the first seed layer and the first base metal layer are nested with each other, on the one hand, the contact performance of the first seed layer and the first base metal layer is improved, the conductivity of the P-type collecting electrode is improved, and the pulling force and the structural stability at the interface of the first seed layer and the first base metal layer are improved; on the other hand, compared with noble metals, some base metals in the first base metal layer are more likely to diffuse, the holes in the first seed layer can be used as receiving positions or accommodation positions for the inward diffusion of metal elements in the first base metal layer, and the problem of recombination caused by the further diffusion of metal elements in the first base metal layer to the inside of the silicon substrate can be greatly avoided. The second seed layer is a honeycomb structure including a plurality of holes, and the second base metal layer includes a plurality of metal particles, in the N-type collecting electrode, at least part of the metal particles are partially filled in the honeycomb structure, and the pulling force and the structural stability at the interface of the second seed layer and the second base metal layer are also improved, and the problem of recombination caused by the further diffusion of metal elements in the second base metal layer to the inside of the silicon substrate can be greatly avoided. In summary, the conductivity, the pulling force and the structural stability of the collecting electrode are improved, and the recombination is reduced.

[0113] In some possible embodiments, in the case that the slurry used by the first seed layer 51 and the second seed layer 61 is different, for a double-sided solar cell, a back contact solar cell, and the like, referring to Figure 9 and Figure 10The size of the hole in the first seed layer electrically connected with the P-type doped layer is larger than the size of the hole in the second seed layer electrically connected with the N-type doped layer. In the case that the size of the corresponding metal particles of the two is the same, more metal particles will enter the hole in the first seed layer electrically connected with the P-type doped layer. Therefore, the nesting degree of the first seed layer electrically connected with the P-type doped layer and the first base metal layer electrically connected with the P-type doped layer at the hole is larger, further enhancing the binding force and pulling force between the two. In the present application, the size of the hole in the first seed layer electrically connected with the P-type doped layer is larger, further enhancing the binding force and pulling force between the two, reducing the difference in the binding force and pulling force between the P-type collector electrode 5 and the P-type doped layer 2 and between the N-type collector electrode 6 and the N-type doped layer 3, thereby reducing the risk of pulling off caused by the imbalance of the binding force of the P-type collector electrode electrically connected with the P-type doped layer. In addition, under normal circumstances, it is difficult to obtain a high doping concentration of the P-type doped layer. Therefore, by enhancing the binding force and pulling force between the first seed layer electrically connected with the P-type doped layer and the first base metal layer electrically connected with the P-type doped layer, the current collecting capacity of the region where the P-type doped layer is located is improved, and the influence of the imbalance of the doping concentration of the P-type doped layer on the electrical performance is reduced. It should be noted that the difference between the sizes of the holes of the two is not specifically limited.

[0114] In the case that the slurry used by the first seed layer 51 and the second seed layer 61 is different, the reason why the size of the hole in the first seed layer is larger than the size of the hole in the second seed layer is mainly that the two kinds of slurry differ in additives, organic solvents, glass frits, etc. (for example, the content of glass frit of the seed layer of the P-type collector electrode is greater than that of the seed layer of the N-type collector electrode), which leads to the difference in the final hole size.

[0115] In some possible embodiments, in the case that the slurry used by the first seed layer 51 and the second seed layer 61 is the same, for double-sided solar cells and back contact solar cells, the size of the hole in the first seed layer electrically connected with the P-type doped layer is approximately equal to the size of the hole in the seed layer electrically connected with the N-type doped layer. The first seed layer 51 and the second seed layer 61 can be integrally formed, and the process is simpler.

[0116] In some possible embodiments, if the slurry used for the first seed layer 51 and the second seed layer 61 is the same or different, for bifacial solar cells and back-contact solar cells, the size of the metal particles in the first base metal layer of the P-type current collector electrode is the same as the size of the metal particles in the second base metal layer of the N-type current collector electrode. This can include being completely the same or approximately the same. The first base metal layer of the P-type current collector electrode and the second base metal layer of the N-type current collector electrode can be integrally formed, which simplifies the process.

[0117] In some possible embodiments, where the slurry used for the first seed layer 51 and the second seed layer 61 is the same or different, for bifacial solar cells and back-contact solar cells, refer to Figure 11 The first seed layer 51 of the P-type collector electrode is continuous along the extension direction L2 of the P-type collector electrode. Figure 11 (b)) or partially intermittent settings Figure 11 (a) The first base metal layer 52 is continuously disposed along the extension direction of the P-type current collector electrode. Specifically, when the first seed layer 51 of the P-type current collector electrode is discontinuously disposed along the extension direction L2 of the P-type current collector electrode, the first seed layer can be made of high-temperature paste. While ensuring contact performance, the discontinuous distribution saves on the amount of high-temperature paste used to manufacture the first seed layer. Furthermore, the first base metal layer 52 can be made of base metal paste, thus helping to reduce battery costs. The continuous placement of the first base metal layer 52 along the extension direction of the P-type current collector electrode achieves effective current conduction. Similarly, the second seed layer of the N-type current collector electrode is continuously or partially discontinuously disposed along the extension direction L2 of the N-type current collector electrode. The discontinuous placement of the second base metal layer along the extension direction of the N-type current collector electrode also saves on the amount of high-temperature paste used to manufacture the second seed layer. Furthermore, the second base metal layer can be made of base metal paste, thus helping to reduce battery costs. The continuous placement of the second base metal layer along the extension direction of the P-type current collector electrode achieves effective current conduction.

[0118] In some possible embodiments, refer to Figure 3 , Figure 4The back surface of the silicon substrate 1 comprises first regions and second regions, which are arranged alternately, that is, one first region, then one second region, and then one first region are arranged in sequence along a direction perpendicular to the extension direction of the P-type or N-type collecting electrodes. The first regions and the second regions can have a spacing therebetween, which can avoid reducing the risk of short circuit, or the first regions and the second regions can have no spacing therebetween, and the risk of short circuit can be avoided by the passivation layer located therebetween. The first regions are provided with the P-type doped layer 2, and the second regions are provided with the N-type doped layer 3. The relative sizes of the first regions and the second regions are not limited herein. The collecting electrodes of the solar cell are all located on the back surface, which is a back contact solar cell, and the front surface is not blocked by the electrodes, so that the solar cell is more beautiful and has better performance. In this case, the solar cell further comprises a passivation layer 4 located on the front surface of the silicon substrate. The specific type of the back contact solar cell is not limited, for example, it can be a BC cell.

[0119] In some possible embodiments, with reference to Figure 1 、 Figure 2 The P-type doped layer 2 is arranged on the front surface of the silicon substrate 1, and the N-type doped layer 3 is arranged on the back surface of the silicon substrate 1, and the solar cell is a bifacial solar cell, for example, a TOPcon (passivated contact) cell. Specifically, the P-type doped layer 2 has weak parasitic absorption of short-wavelength light relative to the N-type doped layer 3, and the P-type doped layer 2 is arranged on the front surface of the silicon substrate 1 to reduce parasitic absorption, which can improve the performance of the cell.

[0120] It should be noted that the foregoing various embodiments of the present application can be implemented separately or in combination with each other in the absence of logical conflicts, which is not limited herein.

[0121] The present application also provides a photovoltaic module, comprising: a plurality of series and / or parallel cell strings, wherein the cell string comprises: an electrical connector and any one of the foregoing solar cells. The electrical connector electrically connects the N-type collecting electrode of one solar cell and the P-type collecting electrode of another solar cell in the at least two foregoing solar cells. The electrical connector mentioned in the present application can be a solder strip, a conductive electrical connector, etc.

[0122] It should be noted that the solar cell and the photovoltaic module provided by the present application can be mutually referred to in terms of their relevant aspects, and the relevant aspects will not be described again in order to avoid repetition.

[0123] It should be noted that, in this document, the terms "comprising", "comprises" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more limitations, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0124] The above describes the embodiments of the present application in connection with the drawings, but the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are merely illustrative, but not restrictive, and those skilled in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, which all belong to the protection of the present application.

Claims

1. A solar cell, characterized in that, include: Silicon substrate; A doped layer is located on at least one side of the silicon substrate along the thickness direction of the silicon substrate; The doped layer includes a P-type doped layer and an N-type doped layer; A passivation layer is disposed on the P-type doped layer and the N-type doped layer; The P-type collector electrode is located on the side of the P-type doped layer away from the silicon substrate. The P-type collector electrode extends through the passivation layer into the P-type doped layer and forms an ohmic contact with the P-type doped layer. The ohmic contact portion between the P-type collector electrode and the doped layer includes a plurality of first metal crystals. Along the width direction of the P-type collector electrode, the width of the distribution area of ​​the first metal crystals is A1. An N-type collector electrode is located on the side of the N-type doped layer away from the silicon substrate. The N-type collector electrode extends through the passivation layer into the N-type doped layer and forms an ohmic contact with the N-type doped layer. The ohmic contact portion between the N-type collector electrode and the doped layer includes a plurality of second metal crystals. Along the width direction of the N-type collector electrode, the width of the distribution area of ​​the second metal crystals is A2, where A1 > A2.

2. The solar cell according to claim 1, characterized in that, Along the width direction of the P-type collector electrode, the distribution density of the first metal crystal in the first metal crystal distribution area is B1, and along the width direction of the N-type collector electrode, the distribution density of the second metal crystal in the second metal crystal distribution area is B2, where B1 < B2.

3. The solar cell according to claim 1, characterized in that, Along the width direction of the P-type collector electrode, the number of the first metal crystals is C1, and along the width direction of the N-type collector electrode, the number of the second metal crystals is C2, where C1 > C2.

4. The solar cell according to claim 1, characterized in that, The size of the first metal crystal is larger than the size of the second metal crystal.

5. The solar cell according to claim 1, characterized in that, The first metal crystal extends into the P-type doped layer to a depth of D1, and the second metal crystal extends into the N-type doped layer to a depth of D2, wherein D1>D2.

6. The solar cell according to claim 1, characterized in that, The ratio of the number of first metal crystals extending into the P-type doped layer to the total number of the first metal crystals is greater than the ratio of the number of second metal crystals extending into the N-type doped layer to the total number of the second metal crystals.

7. The solar cell according to claim 1, characterized in that, The first metal crystal located at the position with the smallest vertical distance from the side surface of the P-type doped layer closest to the silicon substrate has a vertical distance of E1 from the side surface of the P-type doped layer closest to the silicon substrate. The second metal crystal located at the position with the smallest vertical distance from the side surface of the N-type doped layer closest to the silicon substrate has a vertical distance of E2 from the side surface of the N-type doped layer closest to the silicon substrate; E1 < E2.

8. The solar cell according to claim 1, characterized in that, The depth of the first metal crystal extending into the P-type doped layer is F1, and the depth of the second metal crystal extending into the N-type doped layer is F2, wherein F1>F2.

9. The solar cell according to any one of claims 1 to 8, characterized in that, The P-type current collector includes: a first seed layer and a first base metal layer, wherein the first seed layer passes through the passivation layer and is electrically connected to the P-type doped layer, the first base metal layer covers the first seed layer, and the first base metal layer is electrically connected to the P-type doped layer through the first seed layer; the first base metal layer includes a plurality of metal particles, and the first seed layer includes the plurality of first metal crystals; and / or, The N-type current collector electrode includes: a second seed layer and a second base metal layer, the second seed layer passing through the passivation layer and electrically connected to the N-type doped layer, the second base metal layer covering the second seed layer, and the second base metal layer being electrically connected to the N-type doped layer through the second seed layer; the second base metal layer includes a plurality of metal particles, and the second seed layer includes the plurality of second metal crystals.

10. The solar cell according to claim 9, characterized in that, The height of the first seed layer is greater than the height of the second seed layer; and / or, The width of the first seed layer is greater than the width of the second seed layer.

11. The solar cell according to claim 9 or 10, characterized in that, The height of the P-type current collector electrode is less than the height of the N-type current collector electrode; and / or, The width of the P-type collector electrode is smaller than the width of the N-type collector electrode.

12. The solar cell according to claim 9 or 10, characterized in that, The seed layer is a honeycomb structure including multiple holes, and in the same current collector electrode, at least a portion of the metal particles are partially filled in the honeycomb structure; And / or, The size of the hole in the P-type collector electrode is larger than the size of the hole in the N-type collector electrode.

13. The solar cell according to any one of claims 9 to 12, characterized in that, The size of the metal particles in the P-type current collector electrode is the same as the size of the metal particles in the N-type current collector electrode.

14. The solar cell according to any one of claims 9 to 12, characterized in that, The base metal layer is selected from at least one of Cu, Al, Ni, and silver-plated copper; and / or, The seed layer is made of one or more of Al, Zn, Fe, Co, Mg, Ag, Ni, Au, and Pd, and the seed layer is made of a different material than the base metal layer in the same current collector electrode.

15. The solar cell according to any one of claims 9 to 14, characterized in that, The seed layer is disposed continuously or partially discontinuously along the extension direction of the current collector electrode, and the base metal layer is disposed continuously along the extension direction of the current collector electrode.

16. The solar cell according to any one of claims 1 to 15, characterized in that, The back side of the silicon substrate includes a first region and a second region, which are alternately arranged. The first region is provided with the P-type doped layer, and the second region is provided with the N-type doped layer. or, The P-type doped layer is disposed on the front side of the silicon substrate, and the N-type doped layer is disposed on the back side of the silicon substrate.

17. A photovoltaic module, characterized in that, include: Multiple battery strings connected in series and / or in parallel, the battery strings comprising: electrical connectors and solar cells according to any one of claims 1 to 16, the electrical connectors electrically connecting at least two of the solar cells.

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