Solar cell and photovoltaic module

Abstract

To provide a solar cell, a method for preparing the same, and a photovoltaic module, according to the present embodiment relating to the field of photovoltaics.SOLUTION: The solar cell includes: a substrate having a front surface and a rear face that are opposite to each other; a tunneling layer positioned on the rear face of a substrate; and a doped conductive layer positioned on a front face separated away from the substrate, of the tunneling layer. The tunneling layer includes first regions and second regions that are alternately arranged along a first direction. The first regions include first dopant atoms. The doped conductive layer includes: first doped regions each facing the first region; and second doped regions each facing the second region. The first regions and second doped regions have mutually different doping types. The first doped regions include the first atoms, and an atomic percentage of the first dopant atoms in the first doped regions is smaller than an atomic percentage of the first dopant atoms in the first regions. The present invention is advantageous at least in improvement of an open-circuit voltage and photoelectric conversion efficiency of the solar cells.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of solar cells, and in particular, to solar cells and photovoltaic modules.

Background Art

[0002] Fossil energy pollutes the atmosphere and has limited reserves. However, solar energy has the advantages of being clean, pollution-free, and rich in resources. Therefore, solar energy is becoming a core clean energy alternative to fossil energy. Solar cells have excellent photoelectric conversion efficiency and thus are at the center of clean energy applications.

[0003] In order to increase the efficiency of solar cells and the utilization rate of incident light as much as possible, Tunnel Oxide Passivated Contact (TOPCon) cells and Interdigitated Back Contact (IBC) crystalline silicon solar cells have emerged. The tunnel oxide layer and the doped conductive layer installed on the back surface of the TOPCon cell form a passivation contact structure, which can significantly improve the passivation effect and open-circuit voltage of the solar cell, and thus increase the photoelectric conversion efficiency of the solar cell. In the case of IBC cells, since all the electrodes are installed on the back surface of the cell, light shielding by the electrodes installed on the front surface of the cell can be avoided, significantly improving the light absorption of the solar cell, and increasing the photoelectric conversion efficiency of the solar cell.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Embodiments of the present application provide a photovoltaic module that is advantageous for at least improving the open-circuit voltage and photoelectric conversion efficiency of solar cells.

Means for Solving the Problems

[0005] In an embodiment of the present application, a solar cell is provided, the solar cell including: a substrate having opposing front and back surfaces; a tunnel layer located on the back surface of the substrate; and a doped conductive layer located on a surface of the tunnel layer remote from the substrate, the tunnel layer including first and second regions arranged alternately along a first direction, the first region including first dopant atoms, the doped conductive layer including a first doped region facing the first region and a second doped region facing the second region, the first doped region and the second doped region having different doping types, the first doped region including the first dopant atoms, and an atomic percentage of the first dopant atoms in the first doped region being smaller than an atomic percentage of the first dopant atoms in the first region.

[0006] In some embodiments, the ratio of the atomic percentage of the first dopant atoms in the first region to the atomic percentage of the first dopant atoms in the first doped region is 1-5.

[0007] In some embodiments, the atomic percentage of the first dopant atoms in the first region is between 1% and 10%.

[0008] In some embodiments, the atomic percentage of the first dopant atoms in the first doped region is between 0.2% and 5%.

[0009] In some embodiments, the first dopant atoms are N-type atoms.

[0010] In some embodiments, the atomic percentage of the first dopant atoms in the first doped region decreases in a gradient perpendicular to a back surface of the substrate and in a direction away from the substrate.

[0011] In some embodiments, the first region includes a first portion that contacts the substrate, and the atomic percentage of the first dopant atoms in the first portion is greater than the atomic percentage of the first dopant atoms in the first region.

[0012] In some embodiments, the atomic percentage of the first dopant atoms in the first portion is 2% to 20%.

[0013] In some embodiments, in a direction perpendicular to the back surface of the substrate, the ratio of the thickness of the first portion to the thickness of the first region is 0.25 to 0.5.

[0014] In some embodiments, in a direction perpendicular to the back surface of the substrate, the thickness of the first portion is 0.25 nm to 1 nm.

[0015] In some embodiments, the first region includes a second portion that contacts the first doping region, and the atomic percentage of the first dopant atoms in the second portion is greater than the atomic percentage of the first dopant atoms in the first region.

[0016] In some embodiments, the atomic percentage of the first dopant atoms in the second portion is 2% to 20%.

[0017] In some embodiments, in a direction perpendicular to the back surface of the substrate, the ratio of the thickness of the second portion to the thickness of the first region is 0.25 to 0.5.

[0018] In some embodiments, in a direction perpendicular to the back surface of the substrate, the thickness of the second portion is 0.25 nm to 1 nm.

[0019] Correspondingly, embodiments of the present application further provide a photovoltaic module, which includes a cell string formed by connecting a plurality of the solar cells, a sealing layer for covering the surface of the cell string, and a cover plate for covering the surface of the sealing layer away from the cell string.

Advantages of the Invention

[0020] The technical solution provided in the embodiment of the present application has at least the following advantages.

[0021] In the solar cell provided in an embodiment of the present application, since the back surface of the substrate has a passivation contact structure composed of a tunnel layer and a doping conductive layer, carrier recombination on the back surface of the substrate is significantly reduced, and thus the recombination current on the back surface of the substrate is decreased, and the carrier recombination loss of the solar cell can be reduced. Since the doping conductive layer is composed of a first doping region and a second doping region with different doping types, the electrodes of the solar cell can all be provided on the back surface of the solar cell, and thus the influence on the light absorption of the cell by the electrodes provided on the front surface of the solar cell is significantly reduced, and the light absorption of the solar cell can be enhanced. The tunnel layer is composed of a first region and a second region alternately arranged along a first direction, and the first region faces the first doping region. Both the first region and the first doping region contain a first dopant atom, and the atomic percentage of the first dopant atom in the first region is lower than the atomic percentage of the first dopant atom in the first doping region. By making the first dopant atom concentrated in the tunnel layer, the open-circuit voltage of the solar cell is increased. Furthermore, by doping the tunnel layer with the first dopant atom, the tunnel ability of carriers in the tunnel layer is improved, and thus the photoelectric conversion efficiency of the solar cell can be significantly increased.

Brief Description of the Drawings

[0022] One or more embodiments are exemplarily illustrated in the figures in the corresponding accompanying drawings. These exemplary illustrations do not limit the embodiments. Unless otherwise specified, the figures in the accompanying drawings are not limited by scale.

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Embodiments for Carrying Out the Invention

[0023] In some embodiments, as shown in FIG. 1, the IBC cell generally includes a substrate 10, a tunnel dielectric layer 20, a doped conductive layer 30, and a plurality of electrodes 40. Here, the substrate 10 has opposing front and back surfaces, the tunnel dielectric layer 20 is located on the back surface of the substrate 10, the doped conductive layer 30 is located on the surface of the tunnel dielectric layer 20 away from the substrate 10, and the doped conductive layer 30 includes a first doping region 31 and a second doping region 32, where the first doping region 31 and the second doping region 32 have different doping types. Some of the plurality of electrodes 40 are in electrical contact with the first doping region 31, and the remaining electrodes 40 are in electrical contact with the second doping region 32, and the electrodes in electrical contact with different doping regions are insulated from each other.

[0024] In the process of forming the IBC cell, since all the electrodes 40 are installed on the back surface of the substrate 10, the front surface of the formed IBC cell does not have the electrodes 40, avoiding the light shielding by the electrodes 40 installed on the front surface of the IBC cell, and the actual light-receiving area of the front surface of the IBC cell is significantly increased. The back surface of the substrate 10 has a passivation contact structure composed of the tunnel dielectric layer 20 and the doped conductive layer 30, the carrier recombination loss on the back surface of the substrate 10 is significantly reduced, and the IBC cell has a higher light utilization rate and the photoelectric conversion efficiency is significantly improved.

[0025] Also, the IBC cell may include an isolation layer 50 that penetrates the thickness of the doped conductive layer 30. The isolation layer 50 is located between the first doping region 31 and the second doping region 32 and is used to isolate the first doping region 31 and the second doping region 32 having different doping types from each other. Here, the isolation layer 50 may be an insulating dielectric layer made of a deposited insulating dielectric, or may be a groove formed by patterned etching. In FIG. 1, an example is described where the isolation layer 50 penetrates only the thickness of the doped conductive layer 30, but in a specific application, the isolation layer 50 may extend into the interior of the tunnel dielectric layer 20 and further penetrate the thickness of the tunnel dielectric layer 20. In the embodiments of the present application, this is not limited.

[0026] In some of the drawings in the embodiments of the present application, only a part of the structure of the IBC cell is shown. The IBC cell may include other film layers such as a passivation antireflection layer located on the surface away from the substrate of the doping conductive layer and / or a passivation antireflection layer located on the front surface of the substrate. However, these are not described in detail here.

[0027] One embodiment of the present application provides a solar cell. By having a passivation contact structure composed of a tunnel layer and a doping conductive layer on the back surface of the substrate, carrier recombination on the back surface of the substrate can be significantly reduced, and thus the recombination current on the back surface of the substrate can be decreased, and the carrier recombination loss of the solar cell can be reduced. Since the doping conductive layer is composed of a first doping region and a second doping region with different doping types, the electrodes of the solar cell can all be provided on the back surface of the solar cell, and thus the influence on the light absorption of the electrodes provided on the front surface of the solar cell can be significantly reduced, and the light absorption of the solar cell can be enhanced. The tunnel layer is composed of a first region and a second region alternately arranged along a first direction, and the first region faces the first doping region. Both the first region and the first doping region contain first dopant atoms, and the atomic percentage of the first dopant atoms in the first region is lower than the atomic percentage of the first dopant atoms in the first doping region. By concentrating the first dopant atoms in the tunnel layer, the open-circuit voltage of the solar cell can be increased. Furthermore, by doping the first dopant atoms into the tunnel layer, the tunnel ability of carriers in the tunnel layer can be improved, and thus the photoelectric conversion efficiency of the solar cell can be significantly increased.

[0028] Hereinafter, each embodiment of the present application will be described in detail with reference to the drawings. However, as those skilled in the art can understand, although a number of technical details are proposed in the embodiments of the present application to better enable readers to understand the present application, the technical solution claimed by the present application can be realized even without these technical details and various changes and modifications based on the following embodiments.

[0029] One embodiment of the present application provides a solar cell. As shown in FIGS. 2 and 3, FIG. 2 is a diagram showing the overall structure of the solar cell, and FIG. 3 is a top view of the tunnel layer. Here, the X direction is the first direction.

[0030] The solar cell includes a substrate 101 having opposing front and back surfaces, a tunnel layer 102 located on the back surface of the substrate 101, and a doped conductive layer 103 located on the surface of the tunnel layer 102 away from the substrate 101. The tunnel layer 102 includes a first region 121 and a second region 122 alternately arranged along the first direction. The first region 121 contains a first dopant atom. The doped conductive layer 103 includes a first doping region 131 facing the first region 121 and a second doping region 132 facing the second region 122. The first doping region 131 and the second doping region 132 have different doping types. The first doping region 131 contains a first dopant atom, and the atomic percentage of the first dopant atom in the first doping region 131 is smaller than the atomic percentage of the first dopant atom in the first region 121.

[0031] In the solar cell, the back surface of the substrate 101 has a passivation contact structure composed of the tunnel layer 102 and the doped conductive layer 103. The tunnel layer 102 passivates the defects on the surface of the substrate 101 by bonding, and the doped conductive layer 103 applies field passivation to the substrate 101 by the formed electric field, significantly reducing the carrier recombination on the back surface of the substrate 101 and lowering the carrier recombination loss of the solar cell. Since the doped conductive layer 103 is composed of a first doping region 131 and a second doping region 132 with different doping types, all the electrodes of the solar cell can be provided on the back surface, thereby avoiding the light shielding effect caused by the electrodes provided on the front surface of the solar cell and enhancing the light absorption of the solar cell. Here, the front surface of the solar cell refers to the surface on the side with a large intensity of the incident light received by the solar cell, and the back surface of the solar cell refers to the surface on the side with a small intensity of the incident light received by the solar cell.

[0032] Also, the tunnel layer 102 is composed of a first region 121 and a second region 122 that are alternately arranged along the first direction. The first region 121 faces the first doping region 131. The doping types of the first region 121 and the first doping region 131 are the same, and the atomic percentage of the first dopant atoms in the first region 121 is greater than the atomic percentage of the first dopant atoms in the first doping region 131. By concentrating the first dopant atoms in the first region 121 of the tunnel layer 102, the passivation contact structure can achieve a better passivation effect on the substrate 101, increase the open-circuit voltage of the solar cell, and also, since the first region 121 is doped with the first dopant atoms, improve the tunneling ability of the carriers in the first region 121, thereby significantly reducing the carrier collection loss of the solar cell and increasing the photoelectric conversion efficiency of the solar cell.

[0033] Also, in FIG. 2, the case where the first doping region 131 and the second doping region 132 are adjacent to each other is taken as an example for explanation. However, as shown in FIGS. 2 and 4, FIG. 4 is a diagram showing the overall structure of the solar cell. Here, the X direction is the first direction. The solar cell may include a plurality of isolation layers 50 that penetrate the thickness of the stacked structure composed of the tunnel layer 102 and the doping conductive layer 103. The isolation layer 50 is used to separate the first region 121 and the second region 122, and to separate the first doping region 131 and the second doping region 132. The isolation layer 50 may be a groove that directly penetrates the thickness of the stacked structure, or may be a dielectric layer formed of a non-conductive insulating dielectric material. In FIG. 4, the case where the isolation layer 50 directly penetrates the tunnel layer 102 and the doping conductive layer 103 is taken as an example for explanation. However, the isolation layer 50 may penetrate only the thickness of the doping conductive layer 103, or may penetrate only the thickness of the doping conductive layer 103 and extend a certain distance into the interior of the tunnel layer 102. However, in the embodiments of the present application, this is not limited.

[0034] In some embodiments, the substrate 101 may be a P-type semiconductor substrate or an N-type semiconductor substrate. For one of the first doping region 131 and the second doping region 132, the doping type is P-type, and for the other, the doping type is N-type. In the doping conductive layer 103, the doping concentration of the doping region having the same doping type as the substrate 101 is greater than the doping concentration of the substrate 101. Here, the doping concentration can be represented by the atomic percentage in the film layer of the doping element.

[0035] The N-type semiconductor substrate is doped with an N-type doping element, and the N-type doping element may be any one of Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type doping element, and the P-type doping element may be any one of Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In). Similarly, the P-type doping element in the doping conductive layer 103 may be any of the above Group III elements, and the N-type doping element may be any of the above Group V elements.

[0036] In some embodiments, the material of the substrate 101 may be an elemental semiconductor material. The elemental semiconductor material consists of a single element and may be, for example, silicon or germanium. Here, the elemental semiconductor material may be in a single crystal state, polycrystalline state, amorphous state, or microcrystalline state (a state having both a single crystal state and an amorphous state is called a microcrystalline state). For example, silicon may be at least one of single crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0037] In some embodiments, the material of the substrate 101 may be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, materials such as silicon germanium, silicon carbide, gallium arsenide, indium gallium arsenide, perovskite, cadmium telluride, and copper indium selenide. The substrate 101 may be a sapphire substrate, a silicon-on-insulator substrate, or a germanium-on-insulator substrate.

[0038] In some embodiments, the material of the tunnel layer 102 may be at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride.

[0039] In some embodiments, the material of the doped conductive layer 103 may be at least one of materials such as nanocrystalline silicon, polycrystalline silicon, microcrystalline silicon, amorphous silicon, silicon carbide, or titanium nitride.

[0040] In some embodiments, the ratio of the atomic percentage of the first dopant atoms in the first region 121 to the atomic percentage of the first dopant atoms in the first doping region 131 is 1 to 5.

[0041] For the sake of convenience of understanding, take the example where the substrate 101 is an N-type substrate, the doping types of the first region 121 and the first doping region 131 are N-type, and the dopant is phosphorus. The main functions of the tunnel layer 102 and the doped conductive layer 103 are to provide excellent passivation to the substrate 101, reduce carrier recombination on the back surface of the substrate 101, and increase the open-circuit voltage and photoelectric conversion efficiency of the solar cell.

[0042] When the atomic percentage of phosphorus in the first region 121 is significantly greater than the atomic percentage of phosphorus in the first doping region 131, phosphorus is concentrated in the first region 121 of the tunnel layer 102, and the passivation contact structure on the back surface of the substrate 101 can provide a better passivation effect to the substrate 101, further increase the open-circuit voltage of the solar cell, and reduce carrier recombination on the back surface of the substrate 101.

[0043] Another function of the tunnel layer 102 is to achieve selective transport of carriers. When the doped conductive layer 103 consists of a first doping region 131 and a second doping region 132 with different doping types, the portions of the tunnel layer 102 facing the first doping region 131 and the second doping region 132 respectively need to achieve selective transport of holes and electrons. The dopants in the first region 121 and the first doping region 131 are both phosphorus, and the first region 121 needs to selectively transport holes to the first doping region 131. Since a large amount of phosphorus is concentrated in the first region 121, the tunneling ability of holes in the first region 121 is improved. At the same time, the electrons overflowing from the first region 121 also recombine with holes. Moreover, the higher the doping concentration of phosphorus in the first region 121, the greater the recombination of electrons and holes.

[0044] Therefore, in the process of installing the tunnel layer 102 and the doped conductive layer 103, the ratio of the atomic percentage of the first dopant atoms in the first region 121 to the atomic percentage of the first dopant atoms in the first doping region 131 can be set to 1 to 5. For example, it may be 1.1, 1.2, 1.35, 1.5, 1.75, 2, 2.4, 2.8, 3.25, 3.75, 4.5 or 4.85, etc. By setting the ratio of the doping concentration of the first region 121 to the doping concentration of the first doping region 131 within an appropriate range, the open-circuit voltage of the solar cell can be effectively improved, the carrier collection loss on the back surface of the substrate 101 can be reduced, and the recombination effect of holes and electrons in the first region 121 can be controlled within a small range. The influence of the solar cell passivation effect and the improvement of the carrier tunneling ability on the solar energy photoelectric conversion efficiency becomes greater than the influence of the carrier recombination in the first region 121 on the solar cell photoelectric conversion efficiency, effectively enhancing the photoelectric conversion efficiency of the solar cell.

[0045] In some embodiments, the atomic percentage of the first dopant atoms in the first doping region 131 is 0.2% to 5%.

[0046] As can be understood by referring to the analysis and description regarding the above-mentioned doping conductive layer 103 and tunnel layer 102, while the first doping region 131 applies passivation to the substrate 101 together with the first region 121, the first doping region 131 is also used to provide a basis for the lateral transport of carriers, and the carriers in the first doping region 131 tend to concentrate on the electrode that is in electrical contact with the first doping region 131.

[0047] When the atomic percentage of the first dopant atoms in the first doping region 131 is too small, that is, when the doping concentration of the first doping region 131 is too low, the number of movable carriers in the first doping region 131 is too small, and the carriers transported to the first doping region 131 cannot effectively concentrate on the electrode that is in electrical contact with the first doping region 131, resulting in too large carrier collection losses in the solar cell. When the atomic percentage of the first dopant atoms in the first doping region 131 is too high, that is, when the doping concentration of the first doping region 131 is too high, the atomic percentage of the first dopant atoms in the first region 121 becomes higher, and the carrier recombination losses due to the electron-hole recombination effect in the first region 121 increase significantly. As a result, the influence of the increase in carrier recombination losses in the first region 121 is higher than the influence of the decrease in carrier recombination losses on the back surface of the substrate 101.

[0048] Therefore, the atomic percentage of the first dopant atoms in the first doping region 131 can be set to 0.2% - 5%, for example, it can also be 0.25%, 0.5%, 0.8%, 1.2%, 1.5%, 1.8%, 2.25%, 2.75%, 3.5% or 4.5%, etc. This ensures a good lateral transport ability of carriers in the first doping region 131, reduces the carrier collection losses of the solar cell, and at the same time effectively controls the carrier recombination effect in the first region 121, ensuring a reduction in the overall carrier recombination losses of the solar cell, and thus effectively increasing the photoelectric conversion efficiency of the solar cell.

[0049] In some embodiments, in a direction perpendicular to the back surface of the substrate 101 and away from the substrate 101, the atomic percentage of the first dopant atoms in the first doping region 131 decreases in a gradient manner.

[0050] In the process of installing the doping conductive layer 103, the first doping region 131 of the doping conductive layer 103 can be doped with the first dopant atoms by at least one of a plurality of doping processes such as ion implantation or in-situ doping. By adjusting the deposition process of the doping conductive layer 103 and / or the doping process of the first doping region 131, the distribution rule of the first dopant atoms in the first doping region 131 can be adjusted.

[0051] As can be seen by referring to the above analysis of the first doping region 131, the atomic percentage of the first dopant atoms in the first doping region 131 mainly affects the passivation effect on the substrate 101 of the passivation contact structure and the collection loss of the carriers collected by the electrodes through the first doping region 131. In the process of carriers being collected by the electrodes in the first doping region 131, the lateral movement distance of the carriers in the first doping region 131 decreases as the distance between the carriers and the electrodes decreases.

[0052] Therefore, in a direction perpendicular to the back surface of the substrate 101 and away from the substrate 101, it can be set in such a way that the atomic percentage of the first dopant atoms in the first doping region 131 decreases in a gradient manner. When the atomic percentage of the first dopant atoms in the first doping region 131 is constant, the gradient decrease of the atomic percentage can ensure the collection efficiency of the carriers in the first doping region 131, provide stronger field passivation by the substrate 101, and further reduce the carrier recombination on the back surface of the substrate 101.

[0053] Moreover, not only can the atomic percentage of the first dopant atoms in the first doping region 131 be set to change in a gradient manner, but also in a direction perpendicular to the back surface of the substrate 101 and away from the substrate 101, the atomic percentage of the first dopant atoms in the first region 121 can be set to decrease in a gradient manner, so as to reduce the electron-hole recombination within the first region 121.

[0054] In some embodiments, the atomic percentage of the first dopant atoms in the first region 121 is 1% - 10%.

[0055] As can be understood by referring to the above analysis and description regarding the atomic percentage of the first dopant atoms in the first region 121, when the atomic percentage of the first dopant atoms in the first region 121 is too small, there is a limit to the improvement of the passivation effect on the back surface of the substrate 101 by the passivation contact structure on the back surface of the substrate 101, and the carrier recombination loss on the back surface of the substrate 101 decreases slightly. When the atomic percentage of the first dopant atoms in the first region 121 is too large, for the first region 121, in the process of transporting carriers to the first doping region 131, the recombination effect of holes and electrons in the first region 121 is too large, resulting in a significant increase in the carrier recombination loss in the first region 121, and it is easy to cause an inverse increase in the carrier recombination loss of the entire solar cell.

[0056] Therefore, in the process of installing the tunnel layer 102, the atomic percentage of the first dopant atoms in the first region 121 can be set to 1% - 10%, for example, it can also be 1.25%, 1.5%, 2%, 2.5%, 3.5%, 5%, 6.5%, 8% or 9.5%, etc. By setting the atomic percentage of the first dopant atoms in the first region 121 within an appropriate range, the tunneling ability of carriers in the first region 121 can be improved, the carrier recombination loss on the back surface of the substrate 101 can be reduced, the situation where the carrier recombination loss in the first region 121 is too large can be avoided, the carrier recombination loss of the entire solar cell can be reduced, and the open-circuit voltage and photoelectric conversion efficiency of the solar cell can be increased.

[0057] As shown in FIGS. 2 and 5, FIG. 5 is a diagram showing the overall structure of another solar cell, where the X direction is the first direction and the Y direction is the direction perpendicular to the back surface of the substrate 201. In some embodiments, the first region 221 includes a first portion 223 that contacts the substrate 201, and the atomic percentage of the first dopant atoms in the first portion 223 is greater than the atomic percentage of the first dopant atoms in the first region 221.

[0058] In the solar cell shown in FIG. 5, the substrate 201, the doped conductive layer 203, the first doping region 231, the second doping region 232, and the second region 222 of the tunnel layer 202 are respectively similar to the substrate 101, the doped conductive layer 103, the first doping region 131, the second doping region 132, and the second region 122 of the tunnel layer 102 described above, so they will not be described in detail here.

[0059] As can be understood by referring to the above analysis and description of the first region 121, one function of the first region 221 is to provide a passivation effect to the substrate 201, and another function is to selectively transport specific carriers to the first doping region 231 facing the first region 221.

[0060] Therefore, in the process of installing the first region 221, the first region 221 can be installed on a film layer having a high-concentration doping portion, and the high-concentration doping portion faces the substrate 201. That is, the first region 221 includes a first portion 223, the first portion 223 contacts the back surface of the substrate 201, and the atomic percentage of the first dopant atoms in the first portion 223 is greater than the atomic percentage of the first dopant atoms in the first region 221. Here, the atomic percentage of the first dopant atoms in the first region 221 is the average atomic percentage of the first dopant atoms in the first region 221 including the first portion 223. That is, the first region 221 can be regarded as consisting of two parts, namely the first portion 223 and the portion other than the first portion 223, and the doping concentration of the dopant in the first portion 223 is higher than the doping concentration of the dopant in the portion of the first region 221 excluding the first portion 223.

[0061] One of the main surfaces where the first region 221 provides a passivation effect to the substrate 201 is to form an electric field between the substrate 201 and the film layer with a higher doping concentration than that of the substrate 201, and by adjusting the movement tendency of carriers with different polarities by the electric field, the number of carriers with one polarity on the back surface of the substrate 201 facing the first region 221 is made much larger than the number of carriers with the other polarity. Thereby, after the first portion 223 is formed, the electric field for adjusting the movement tendency of carriers with different polarities becomes stronger, further improving the passivation effect of the first region 221 and the first doping region 231 on the substrate 101, reducing the carrier loss on the back surface of the substrate 201, and increasing the open-circuit voltage of the solar cell.

[0062] Also, as shown in FIGS. 5 and 6, FIG. 6 is a diagram showing the overall structure of the solar cell, and the solar cell may further include a plurality of isolation layers 50. Here, since the structure of the isolation layer 50 in FIG. 6 is similar to the structure of the isolation layer 50 described above, the description of specific materials and standard parameters is omitted here. The isolation layer 50 can avoid the recombination of holes and electrons between the first doping region 231 and the second doping region 232, and can increase the lifetime of carriers.

[0063] In some embodiments, the atomic percentage of the first dopant atoms in the first portion 223 is 2% to 20%.

[0064] When the first region 221 is disposed in a structure including the first portion 223, the atomic percentage of the first dopant atoms in the first portion 223 affects the electric field strength. When the atomic percentage of the first dopant atoms in the first portion 223 is low, the improvement in the field passivation effect due to the installation of the first portion 223 is not obvious, and the carrier recombination on the back surface of the substrate 201 cannot be effectively reduced. When the atomic percentage of the first dopant atoms in the first portion 223 is too high, in the process of transporting carriers to the first doping region 231, the recombination of electrons and holes in the first portion 223 is too strong, which easily leads to a significant increase in the overall carrier recombination loss in the first region 221, and ultimately leads to a significant increase in the carrier recombination loss of the entire solar cell.

[0065] Therefore, in the process of installing the tunnel layer 202, the atomic percentage of the first dopant atoms in the first portion 223 can be set to 2% to 20%, for example, it may be 2.5%, 3%, 4%, 5%, 7.5%, 10%, 13%, 16% or 19%. By setting the doping concentration of the dopant in the first portion 223 within an appropriate range, the passivation effect of the passivation contact structure on the substrate 201 and the tunnel ability of carriers in the first region 221 are significantly enhanced, and the overall carrier recombination loss in the first region 221 is effectively suppressed, ensuring that the carrier recombination loss of the solar cell is significantly reduced and the photoelectric conversion efficiency of the solar cell is increased.

[0066] In addition, the tunnel layer 202 includes a plurality of first regions 221. In the first portion 223 in each first region 221, the atomic percentage of the first dopant atoms may be the same or different. In the embodiments of the present application, it is not limited thereto.

[0067] In some embodiments, in the direction perpendicular to the back surface of the substrate 201, the ratio of the thickness of the first portion 223 to the thickness of the first region 221 is 0.25 to 0.5.

[0068] In the direction perpendicular to the back surface of the substrate 201, the thickness of the first portion 223 refers to the average distance h1 between two opposing surfaces of the first portion 223 in the direction perpendicular to the back surface of the substrate 201, and the thickness of the first region 221 refers to the average distance h2 between two opposing surfaces of the first region 221 in the direction perpendicular to the back surface of the substrate 201.

[0069] As can be seen from the above description and analysis of the first portion 223, while the first portion 223 contributes to enhancing the passivation effect of the passivation contact structure on the substrate 201, it significantly enhances the electron-hole recombination effect in the first portion 223, thus easily affecting the carrier recombination loss of the first region 221 and the entire solar cell.

[0070] The factors affecting the magnitude of the carrier recombination loss in the first portion 223 include the atomic percentage of the first dopant atoms in the first portion 223 and the migration distance of the carriers during the process of passing through the first portion 223. When the atomic percentage of the first dopant atoms is constant, the greater the thickness of the first portion 223, the greater the carrier recombination loss in the first portion 223. Also, when the atomic percentage of the first dopant atoms in the first region 221 is constant, the greater the thickness of the first portion 223, the lower the atomic percentage of the first dopant atoms per unit thickness in the first portion 223, which is likely to result in a smaller improvement in the passivation effect of the passivation contact structure on the substrate 201.

[0071] Therefore, in the process of installing the tunnel layer 202, in the direction perpendicular to the back surface of the substrate 201, the ratio of the thickness of the first portion 223 to the thickness of the first region 221 can be set to 0.25 to 0.5, and for example, it may be 0.275, 0.3, 0.325, 0.375, 0.425, or 0.45, etc. The first portion 223 can significantly enhance the passivation effect of the passivation contact structure on the substrate 201, suppress the carrier recombination loss in the first region 221 within a small range, and significantly reduce the carrier recombination loss of the entire solar cell.

[0072] In some embodiments, in the direction perpendicular to the back surface of the substrate 201, the thickness of the first portion 223 is 0.25 nm to 1 nm. As can be understood by referring to the above description and analysis of the thickness of the first portion 223, since the thickness of the tunnel layer 202, which is the tunnel oxide layer in the passivation contact structure, is usually 1 nm to 2 nm, in the process of installing the tunnel layer 202, in the direction perpendicular to the back surface of the substrate 201, the thickness of the first portion 223 can be set to 0.25 nm to 1 nm, and for example, it may be 0.3 nm, 0.35 nm, 0.5 nm, 0.7 nm, or 0.9 nm, etc.

[0073] As shown in FIGS. 2 and 7, FIG. 7 is a diagram showing the overall structure of another solar cell, where the X direction is the first direction and the Y direction is the direction perpendicular to the back surface of the substrate 301. In some embodiments, the first region 321 includes a second portion 324, the second portion 324 contacts the first doping region 331, and the atomic percentage of the first dopant atoms in the second portion 324 is greater than the atomic percentage of the first dopant atoms in the first region 321.

[0074] In the solar cell shown in FIG. 7, the substrate 301, the doping conductive layer 303, the first doping region 331, the second doping region 332, and the second region 322 of the tunnel layer 302 are respectively similar to the substrate 101, the doping conductive layer 103, the first doping region 131, the second doping region 132, and the second region 122 of the tunnel layer 102 described above, so they will not be described in detail here.

[0075] As can be seen by referring to the above description and analysis of the first region 121, one function of the first region 321 is to provide a passivation effect to the substrate 301, and another function is to selectively transport specific carriers to the first doping region 331 facing the first region 321. The first region 321 provides a passivation effect to the substrate 301 mainly including two aspects. One is that the hydrogen overflowing from the first region 321 bonds with the back surface of the substrate 301 to passivate the defects on the back surface of the substrate 301. The other is that since the doping concentration and / or doping type are different between the first region 321 and the substrate 301, an electric field is formed on the back surface of the substrate 301. By using the electric field to adjust the movement tendency of carriers with different polarities, the number of carriers with one polarity on the back surface of the substrate 301 facing the first region 321 is made much larger than the number of carriers with the other polarity.

[0076] Therefore, in the process of installing the first region 321, the first region 321 can be set as a film layer with a high-concentration doping portion, and the high-concentration doping portion is away from the substrate 301. That is, the first region 321 includes a second portion 324, the second portion 324 is located on the side away from the back surface of the substrate 301 of the first region 321, and the atomic percentage of the first dopant atoms in the second portion 324 is greater than the atomic percentage of the first dopant atoms in the first region 321. Here, the atomic percentage of the first dopant atoms in the first region 321 is the average atomic percentage of the first dopant atoms in the first region 321 including the second portion 324. That is, the first region 321 can be regarded as being composed of two portions, namely the second portion 324 and the portion other than the second portion 324, and the doping concentration of the dopant in the second portion 324 is higher than the doping concentration of the dopant in the portion of the first region 321 excluding the second portion 324.

[0077] After the first region 321 is installed in the structure including the second portion 324, the atomic percentage of the first dopant atoms in the second portion 324 becomes higher than the average atomic percentage of the first dopant atoms in the first region 321, and a stronger electric field can be formed between the second portion 324 and the substrate 301. As a result, the field passivation effect on the back surface of the substrate 301 of the passivation contact structure can be enhanced. At the same time, since the percentage of the first dopant atoms in the second portion 324 is high, when the average percentage of the first dopant atoms in the first region 321 is constant, the concentration of the first dopant atoms in the portion of the first region 321 close to the back surface of the substrate 301 becomes low, and the first region 321 can better allow hydrogen to overflow to passivate the defects on the back surface of the substrate 301, further reducing the carrier recombination on the back surface of the substrate 301, and thus reducing the carrier recombination loss of the solar cell.

[0078] Also, as shown in FIGS. 7 and 8, FIG. 8 is a diagram showing the overall structure of the solar cell, and the solar cell may further include a plurality of isolation layers 50. Here, since the structure of the isolation layer 50 in FIG. 8 is similar to the structure of the isolation layer 50 described above, specific materials and standard parameters are omitted here. The isolation layer 50 can avoid the recombination of holes and electrons between the first doping region 331 and the second doping region 332, and can increase the carrier lifetime.

[0079] In some embodiments, the atomic percentage of the first dopant atoms in the second portion 324 is 2% to 20%.

[0080] When the first region 321 is disposed in the structure including the second portion 324, the atomic percentage of the first dopant atoms in the second portion 324 affects the electric field strength. When the atomic percentage of the first dopant atoms in the second portion 324 is low, the improvement in the passivation effect due to the installation of the second portion 324 is not obvious, and the carrier recombination on the back surface of the substrate 301 cannot be effectively reduced. When the atomic percentage of the first dopant atoms in the second portion 324 is too high, in the process of transporting carriers to the first doping region 331, the recombination of electrons and holes in the second portion 324 is too strong, which easily leads to a significant increase in the overall carrier recombination loss in the first region 321, and then leads to a significant increase in the carrier recombination loss of the entire solar cell.

[0081] Therefore, in the process of installing the tunnel layer 302, the atomic percentage of the first dopant atoms in the second portion 324 can be set to 2% to 20%, for example, it may be 2.5%, 3%, 4%, 5%, 7.5%, 10%, 13%, 16% or 19%. By setting the doping concentration of the dopant in the second portion 324 within an appropriate range, the passivation effect of the passivation contact structure on the substrate 301 can be significantly enhanced, the overall carrier recombination loss in the first region 321 can be effectively suppressed, the carrier recombination loss of the solar cell can be ensured to be significantly reduced, and the photoelectric conversion efficiency of the solar cell can be increased.

[0082] In addition, the tunnel layer 302 includes a plurality of first regions 321. In the second portion 324 of each first region 321, the atomic percentage of the first dopant atoms may be the same or different. In the embodiments of the present application, this is not limited.

[0083] In some embodiments, in the direction perpendicular to the back surface of the substrate 201, the ratio of the thickness of the second portion 324 to the thickness of the first region 221 is 0.25 to 0.5.

[0084] In the direction perpendicular to the back surface of the substrate 301, the thickness of the second portion 324 refers to the average distance h3 between two opposing surfaces of the second portion 324 in the direction perpendicular to the back surface of the substrate 301, and the thickness of the first region 321 refers to the average distance h2 between two opposing surfaces of the first region 321 in the direction perpendicular to the back surface of the substrate 301.

[0085] As can be seen with reference to the above description and analysis of the second portion 324, while the second portion 324 contributes to enhancing the passivation effect of the passivation contact structure on the substrate 301, the electron-hole recombination effect in the second portion 324 also becomes significantly stronger, and it is easy to affect the carrier recombination loss in the first region 321 and the entire solar cell.

[0086] The factors affecting the magnitude of the carrier recombination loss in the second portion 324 include the atomic percentage of the first dopant atoms in the second portion 324 and the migration distance of the carriers during the process of passing through the second portion 324. When the atomic percentage of the first dopant atoms is constant, the greater the thickness of the second portion 324, the greater the carrier recombination loss in the second portion 324. Also, when the atomic percentage of the first dopant atoms in the first region 321 is constant, the greater the thickness of the second portion 324, the lower the atomic percentage of the first dopant atoms per unit thickness in the second portion 324, which easily leads to a smaller improvement in the passivation effect of the passivation contact structure on the substrate 301.

[0087] Therefore, in the process of installing the tunnel layer 302, in the direction perpendicular to the back surface of the substrate 301, the ratio of the thickness of the second portion 324 to the thickness of the first region 321 can be set to 0.25 to 0.5, and for example, it may be 0.275, 0.3, 0.325, 0.375, 0.425, or 0.45, etc. The second portion 324 significantly enhances the passivation effect of the passivation contact structure on the substrate 301, suppresses the carrier recombination loss in the first region 321 within a small range, and significantly reduces the carrier recombination loss of the entire solar cell.

[0088] In some embodiments, in the direction perpendicular to the back surface of the substrate 301, the thickness of the second portion 324 is 0.25 nm to 1 nm. As can be understood by referring to the above description and analysis of the thickness of the second portion 324, in the passivation contact structure, since the thickness of the tunnel layer 302, which is the tunnel oxide layer, is usually 1 nm to 2 nm, in the process of installing the tunnel layer 302, in the direction perpendicular to the back surface of the substrate 301, the thickness of the second portion 324 can be set to 0.25 nm to 1 nm, and for example, it may be 0.3 nm, 0.35 nm, 0.5 nm, 0.7 nm, or 0.9 nm, etc.

[0089] In some embodiments, the solar cell may further include a first passivation layer and a plurality of electrodes located on the surface of the doped conductive layer 303 away from the substrate 301, and the electrodes penetrate the first passivation layer and are in electrical contact with the doped conductive layer 303. The material of the first passivation layer includes at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride. The first passivation layer has a single-layer structure or a stacked structure. In the case of a stacked structure, the structures of the layers are sequentially stacked along the first direction, and the materials of different layers may be different from each other, or the materials of some layers may be the same and different from the materials of other layers. For example, the stacked structure may be a two-layer structure composed of a stacked silicon nitride layer and an aluminum oxide layer.

[0090] In some embodiments, the solar cell may further include a second passivation layer located on the front surface of the substrate 301. The material of the second passivation layer may include at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride. Similarly, the second passivation layer may have a single-layer structure or a stacked structure. In the embodiments of the present application, it is not limited thereto.

[0091] In addition, the surface of the first passivation layer away from the substrate 301 may be a smooth surface or a concavo-convex surface. That is, the side of the first passivation layer away from the substrate 301 exhibits a concavo-convex morphology, thereby extending the optical path length of the incident light in the solar cell. Similarly, the surface of the second passivation layer away from the substrate 301 may be a smooth surface or a concavo-convex surface. When the side of the second passivation layer away from the substrate 301 exhibits a concavo-convex morphology, the second passivation layer can significantly reduce the light reflection of the solar cell with respect to the incident light, thereby improving the light absorption amount of the solar cell and enhancing the photoelectric conversion efficiency of the solar cell.

[0092] Also, as shown in FIGS. 2 and 9, FIG. 9 is a diagram showing the overall structure of the solar cell. The battery structure shown in the foregoing embodiments of the present application is described by taking the case where the solar cell is an IBC cell as an example. In some embodiments, the solar cell may be a TOPCon cell. When the solar cell is a TOPCon cell, the back surface of the substrate 401 has a tunnel layer 402 and a doped conductive layer 403 located on the surface of the tunnel layer 402 away from the substrate 401. The front surface of the substrate 401 has an emitter 404. The doping type of the doped conductive layer 403 is the same as the doping type of the substrate 401, and the emitter 404 and the substrate 401 have different doping types. That is, both the substrate 401 and the doped conductive layer 403 contain a first dopant atom, and the emitter 404 contains a second dopant atom. The atomic percentage of the first dopant atom in the doped conductive layer 403 is higher than the atomic percentage of the first dopant atom in the substrate 401 and lower than the atomic percentage of the first dopant atom in the tunnel layer 402. That is, the first dopant atoms can be concentrated in the tunnel layer 402 on the back surface of the TOPCon cell, and the passivation effect and open-circuit voltage of the TOPCon cell can be enhanced.

[0093] In some embodiments, the ratio of the atomic percentage of the first dopant atom in the tunnel layer 402 to the atomic percentage of the first dopant atom in the doped conductive layer 403 is 1 to 5, and may be, for example, 1.1, 1.2, 1.35, 1.5, 1.75, 2, 2.4, 2.8, 3.25, 3.75, 4.5, or 4.85, etc.

[0094] In some embodiments, the atomic percentage of the first dopant atom in the doped conductive layer 403 is 0.2% to 5%, and may be, for example, 0.25%, 0.5%, 0.8%, 1.2%, 1.5%, 1.8%, 2.25%, 2.75%, 3.5%, or 4.5%, etc.

[0095] In some embodiments, the atomic percentage of the first dopant atoms in the doped conductive layer 403 decreases with a gradient along the direction perpendicular to the back surface of the substrate 401 and away from the substrate 401.

[0096] In some embodiments, the atomic percentage of the first dopant atoms in the tunnel layer 402 is 1% - 10%, and may be, for example, 1.25%, 1.5%, 2%, 2.5%, 3.5%, 5%, 6.5%, 8% or 9.5%, etc.

[0097] Note that since the substrate 410 in the TOPCon cell is similar to the substrate 101 in the IBC cell, the description thereof is omitted here. Also, the doped conductive layer 403 in the TOPCon cell can be analogized to the first doping region 131 in the IBC cell, the tunnel layer 402 in the TOPCon cell can be analogized to the first region 121 in the IBC cell, and the emitter 404 in the TOPCon cell can be analogized to the second doping region 132 in the IBC cell.

[0098] Also, since the material of the doped conductive layer 403 is similar to the material of the first doping region 131, and the material of the tunnel layer 402 is similar to the material of the first region 121, the description thereof is omitted here. The material of the emitter 404 may be similar to that of the substrate 401, and may also contain at least one of aluminum oxide, silicon oxide, and silicon nitride.

[0099] As shown in FIGS. 9 and 10, FIG. 10 is a diagram showing the overall structure of another solar cell, where the Y direction is the direction perpendicular to the back surface of the substrate 401. In some embodiments, the tunnel layer 402 includes a first portion 421, the first portion 421 is in contact with the substrate 401, and the atomic percentage of the first dopant atoms in the first portion 421 is greater than the atomic percentage of the first dopant atoms in the tunnel layer 402. Here, the atomic percentage of the first dopant atoms in the tunnel layer 402 refers to the average atomic percentage of the first dopant atoms in the tunnel layer 402 including the first portion 421. That is, the tunnel layer 402 can be regarded as consisting of two parts, the first portion 421 and the portion other than the first portion 421, and the doping concentration of the dopant in the first portion 421 is higher than the doping concentration of the dopant in the portion of the tunnel layer 402 excluding the first portion 421.

[0100] In some embodiments, in the direction perpendicular to the back surface of the substrate 401, the ratio of the thickness of the first portion 421 to the thickness of the tunnel layer 402 is 0.25 to 0.5, and may be, for example, 0.275, 0.3, 0.325, 0.375, 0.425 or 0.45. The thickness of the first portion 421 in the direction perpendicular to the back surface of the substrate 401 is 0.25 nm to 1 nm, and may be, for example, 0.3 nm, 0.35 nm, 0.5 nm, 0.7 nm or 0.9 nm.

[0101] As shown in FIGS. 9 and 11, FIG. 11 is a diagram showing the overall structure of another solar cell, where the Y direction is the direction perpendicular to the back surface of the substrate 401. In some embodiments, the tunnel layer 402 includes a second portion 422 that contacts the doped conductive layer 403, and the atomic percentage of the first dopant atoms in the second portion 422 is greater than the atomic percentage of the first dopant atoms in the tunnel layer 402. Here, the atomic percentage of the first dopant atoms in the tunnel layer 402 refers to the average atomic percentage of the first dopant atoms in the tunnel layer 402 including the second portion 422. That is, the tunnel layer 402 can be regarded as consisting of two portions, namely the second portion 422 and the portion other than the second portion 422, and the doping concentration of the dopant in the second portion 422 is higher than the doping concentration of the dopant in the portion of the tunnel layer 402 excluding the second portion 422.

[0102] In some embodiments, in the direction perpendicular to the back surface of the substrate 401, the ratio of the thickness of the second portion 422 to the thickness of the tunnel layer 402 is 0.25 to 0.5, and may be, for example, 0.275, 0.3, 0.325, 0.375, 0.425 or 0.45, etc. The thickness of the second portion 422 in the direction perpendicular to the back surface of the substrate 401 is 0.25 nm to 1 nm, and may be, for example, 0.3 nm, 0.35 nm, 0.5 nm, 0.7 nm or 0.9 nm, etc.

[0103] As shown in FIGS. 9 and 12, FIG. 12 is a diagram showing the overall structure of another solar cell, where the Y direction is the direction perpendicular to the back surface of the substrate 401. In some embodiments, the solar cell may further include a passivation antireflection layer 405 and an electrode 406 located on the front and back surfaces of the substrate 401. The passivation antireflection layer 405 covers the semiconductor conductive layer located on the front and back surfaces of the substrate 401, and the electrode 406 penetrates the passivation antireflection layer 405 and is in electrical contact with the semiconductor conductive layer. Here, the semiconductor conductive layer includes an emitter 404 and a doped conductive layer 403. Since the structure and material of the passivation antireflection layer 405 are similar to those of the aforementioned first passivation layer, the description is omitted here.

[0104] In addition, the features of each of the above embodiments not only exist independently in the solar cell, but also may be implemented in combination with each other as long as there is no technical conflict and without exceeding the inventive concept of the embodiments of the present application. Some embodiments of the present application are described by taking the IBC cell as an example, and some embodiments are described by taking the TOPCon cell as an example. As long as there is no technical conflict, the features applied to one solar cell in each embodiment may be combined and applied to other solar cells. The embodiments of the present application are omitted here.

[0105] As described above, the embodiments of the present application provide a solar cell. By having a passivation contact structure composed of a tunnel layer and a doped conductive layer on the back surface of the substrate, the carrier recombination on the back surface of the substrate can be significantly reduced, and thus the recombination current on the back surface of the substrate can be decreased, and the carrier recombination loss of the solar cell can be reduced. Since the doped conductive layer is composed of a first doping region and a second doping region with different doping types, the electrodes of the solar cell can all be provided on the back surface of the solar cell, and thus the influence of the electrodes provided on the front surface of the solar cell on the light absorption of the cell can be significantly reduced, and the light absorption of the solar cell can be enhanced. The tunnel layer is composed of a first region and a second region alternately arranged along a first direction, and the first region faces the first doping region. Both the first region and the first doping region contain a first dopant atom, and the atomic percentage of the first dopant atom in the first region is lower than the atomic percentage of the first dopant atom in the first doping region. By making the first dopant atom concentrate in the tunnel layer, the open-circuit voltage of the solar cell is further improved, the carrier recombination loss is reduced, and the photoelectric conversion efficiency of the solar cell is increased.

[0106] Therefore, as shown in FIG. 13, an embodiment of the present application provides a photovoltaic module including a cell string 1101 formed by connecting a plurality of the solar cells and / or the cells formed by the manufacturing method, a sealing layer 1102 for covering the surface of the cell string 1101, and a cover plate 1103 for covering the surface of the sealing layer 1102 away from the cell string 1101. The solar cells are electrically connected in whole or in a plurality of divided forms to form a plurality of cell strings 1101, and the plurality of cell strings 1101 are electrically connected in series and / or in parallel.

[0107] In some embodiments, the plurality of cell strings 1101 may be electrically connected by a conduction band 1104. The sealing layer 1102 covers the front and back surfaces of the solar cell. Specifically, the sealing layer 1102 may be an organic sealing adhesive film such as an ethylene vinyl acetate copolymer (EVA) adhesive film, a polyethylene-octene copolymer (POE) adhesive film, or a polyethylene terephthalate (PET) adhesive film. In some embodiments, the cover plate 1103 may be a cover plate 1103 having a light transmission function such as a glass cover plate or a plastic cover plate. The surface of the cover plate 1103 facing the sealing layer 1102 may be an uneven surface, which can improve the utilization rate of incident light.

[0108] Although the present application is disclosed as above in the preferred embodiments, it does not limit the scope of the claims. Those skilled in the art can make some possible variations and modifications without departing from the concept of the present application. Therefore, the protection scope of the present application should follow the scope defined by the claims of the present application.

Claims

1. a substrate having opposing front and back surfaces, a tunneling layer located on the back surface of the substrate, and a doped conductive layer located on a surface of the tunneling layer remote from the substrate; the tunnel layer includes first and second regions alternately arranged along a first direction, the first region includes first dopant atoms; the doped conductive layer includes a first doped region opposite the first region and a second doped region opposite the second region, the first doped region and the second doped region having different doping types, the first doped region includes the first dopant atoms, and an atomic percentage of the first dopant atoms in the first doped region is smaller than an atomic percentage of the first dopant atoms in the first region; A solar cell characterized by:

2. a ratio of the atomic percentage of the first dopant atoms in the first region to the atomic percentage of the first dopant atoms in the first doped region is between 1 and 5; The solar cell according to claim 1 .

3. the atomic percentage of the first dopant atoms in the first region is between 1% and 10%; The solar cell according to claim 2 .

4. The atomic percentage of the first dopant atoms in the first doping region is between 0.2% and 5%; The solar cell according to claim 2 .

5. The first dopant atom is an N-type atom; The solar cell according to claim 1 .

6. the atomic percentage of the first dopant atoms in the first doped region decreases in a gradient in a direction perpendicular to a back surface of the substrate and away from the substrate; The solar cell according to claim 1 .

7. the first region includes a first portion, the first portion contacts the substrate, and an atomic percentage of the first dopant atoms in the first portion is greater than an atomic percentage of the first dopant atoms in the first region; The solar cell according to claim 1 .

8. the atomic percentage of the first dopant atoms in the first portion is between 2% and 20%; The solar cell according to claim 7 .

9. In a direction perpendicular to the rear surface of the substrate, the ratio of the thickness of the first portion to the thickness of the first region is 0.25 to 0.

5. The solar cell according to claim 7, characterized in that...

10. In a direction perpendicular to the back surface of the substrate, the thickness of the first portion is 0.25 nm to 1 nm. The solar cell according to claim 9, characterized in that...

11. The first region includes a second portion, the second portion contacts the first doping region, and the atomic percentage of the first dopant atoms in the second portion is greater than the atomic percentage of the first dopant atoms in the first region. The solar cell according to claim 1, characterized in that...

12. The atomic percentage of the first dopant atoms in the second portion is 2% to 20%. The solar cell according to claim 11, characterized in that...

13. In a direction perpendicular to the back surface of the substrate, the ratio of the thickness of the second portion to the thickness of the first region is 0.25 to 0.

5. The solar cell according to claim 11, characterized in that...

14. In a direction perpendicular to the back surface of the substrate, the thickness of the second portion is 0.25 nm to 1 nm. The solar cell according to claim 13, characterized in that...

15. A cell string formed by connecting the solar cells according to any one of claims 1 to 14, A sealing layer for covering the surface of the cell string, A cover plate for covering the surface of the sealing layer away from the cell string, and comprising: The photovoltaic module, characterized in that...

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