Solar cell and manufacturing method for the same, and photovoltaic module

Abstract

To provide a solar cell that is advantageous in improving the use rate of light of the solar cell, a manufacturing method for the solar cell, and a photovoltaic module.SOLUTION: A solar cell includes a substrate having a front surface and a back surface that face each other, a first doped layer and a second doped layer arranged alternately along a first direction on the back surface, in which the first doped layer and the adjacent second doped layer are separated by a separation region, the doping type of the first doped layer and that of the second doped layer are different, a part of the back surface is exposed by the separation region, the side wall of the first doped layer toward the separation region is a first inclined side wall, and the side wall of the second doped layer toward the separation region is a second inclined side wall, and a first electrode in electric contact with the first doped layer and a second electrode in electric contact with the second doped layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of photovoltaic power generation, and more particularly to solar cells and their manufacturing methods, and photovoltaic modules.

Background Art

[0002] Currently, with the gradual depletion of fossil energy, solar cells are being increasingly widely used as a new energy alternative. A solar cell is a device that converts solar light energy into electrical energy. Solar cells utilize the photovoltaic principle to generate carriers, and then extract the carriers through electrodes, thereby promoting the efficient utilization of electrical energy.

[0003] Current solar cells mainly include single-layer cells, such as IBC cells (Interdigitated Back Contact), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and rear cell), HIT / HJT cells (Heterojunction Technology), and perovskite cells. In order to improve the photoelectric conversion efficiency of solar cells, different film layer arrangements and functional limitations are used to reduce light loss and reduce the recombination of photo-generated carriers on the surface and inside of the silicon substrate.

[0004] However, there is still room to improve the utilization rate of light in current IBC cells.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Embodiments of the present disclosure provide a solar cell, a manufacturing method thereof, and a photovoltaic module that are advantageous for at least improving the utilization rate of light in the solar cell.

Means for Solving the Problems

[0006] According to some embodiments of the present disclosure, an embodiment of the present disclosure includes a substrate having opposing front and back surfaces, and a first doped layer and a second doped layer alternately arranged along a first direction on the back surface, wherein a separation region separates the second doped layer adjacent to the first doped layer, the doping type of the first doped layer is different from the doping type of the second doped layer, a part of the back surface is exposed by the separation region, a side wall of the first doped layer facing the separation region is a first inclined side wall, and a side wall of the second doped layer facing the separation region is a second inclined side wall, and provides a solar cell including the first doped layer and the second doped layer, a first electrode in electrical contact with the first doped layer, and a second electrode in electrical contact with the second doped layer.

[0007] In some embodiments, an angle between the first inclined side wall and a surface of the first doped layer facing the back surface is a first acute angle, and an angle between the second inclined side wall and a surface of the second doped layer facing the back surface is a second acute angle.

[0008] In some embodiments, the first angle is less than or equal to the second angle.

[0009] In some embodiments, the first angle is in a range of 25° to 60°, and the second angle is in a range of 30° to 65°.

[0010] In some embodiments, the back surface exposed by the separation region has a pile structure, and the pile structure includes a plurality of pyramid structures.

[0011] In some embodiments, a width of a bottom surface of one of the pyramid structures is 2 μm to 4 μm in a direction parallel to the back surface.

[0012] In some embodiments, the first inclined side wall includes a first sub-inclined side wall, a platform surface, and a second sub-inclined side wall sequentially connected in a direction away from the back surface of the substrate.

[0013] In some embodiments, in a direction perpendicular to the back surface of the substrate, a distance between a surface of the first doped layer on a side away from the substrate and the front surface of the substrate is greater than a distance between a surface of the second doped layer on a side away from the substrate and the front surface of the substrate, where the platform surface is closer to the back surface than the surface of the second doped layer on the side away from the substrate.

[0014] In some embodiments, in a direction perpendicular to the back surface of the substrate, a thickness of the second sub-inclined sidewall is smaller than a thickness of the first sub-inclined sidewall.

[0015] In some embodiments, with respect to the back surface, a gradient of the second sub-inclined sidewall is greater than a gradient of the first sub-inclined sidewall.

[0016] In some embodiments, in a direction perpendicular to the back surface of the substrate, a distance between a surface of the first doped layer on a side away from the substrate and the front surface of the substrate is less than or equal to a distance between a surface of the second doped layer on a side away from the substrate and the front surface of the substrate.

[0017] In some embodiments, the first inclined sidewall is a continuous inclination.

[0018] In some embodiments, the second inclined sidewall is a continuous inclination.

[0019] In some embodiments, dopant ions in the first doped layer include boron ions, and dopant ions in the second doped layer include phosphorus ions.

[0020] According to some embodiments of the present disclosure, the method for manufacturing a solar cell includes the steps of: providing a substrate having opposite front and back surfaces; forming a first first-doped layer on the back surface of the substrate; performing a first patterning process on the first first-doped layer to form a plurality of first-doped layers arranged at intervals in a first direction, wherein sidewalls of the first-doped layers are first first-inclined sidewalls; forming a first second-doped layer on the back surface of the substrate, the first second-doped layer having a doping type different from that of the first-doped layer; performing a second patterning process on the first second-doped layer to form a second-doped layer, wherein the first-doped layer and the second-doped layer are alternately arranged along the first direction on the back surface of the substrate, and a separation region separates the first-doped layer from the adjacent second-doped layer, and a part of the back surface is exposed by the separation region, wherein after the second patterning process, the first first-inclined sidewalls become first-inclined sidewalls, the first-inclined sidewalls are sidewalls of the first-doped layer facing the separation region, and sidewalls of the second-doped layer facing the separation region are second-inclined sidewalls; and forming a first electrode in electrical contact with the first-doped layer and a second electrode in electrical contact with the second-doped layer.

[0021] In some embodiments, when forming the first first-doped layer, a first first-oxide layer is also formed on the surface of the first first-doped layer, and in the process of the first patterning process the steps include: patterning the first first-oxide layer by first laser light treatment to form a first-oxide layer on the surface of the first-doped layer away from the substrate; and removing the first first-doped layer exposed from the first-oxide layer by a first wet etching process, and further including the step of removing the first-oxide layer before forming the first electrode and the second electrode.

[0022] In some embodiments, the laser power of the first laser light treatment is 20W to 30W, and the process time of the first wet etching process is 500s to 1000s.

[0023] In some embodiments, in the step of forming the first second doped layer, the first second doped layer is also disposed on the surface of the first doped layer, and a first second oxide layer is also formed on the surface of the first second doped layer. The second patterning process includes a step of performing a second laser light treatment to pattern the first second oxide layer to form a second oxide layer that exposes at least the first second doped layer corresponding to the separation region, and a step of performing a second wet etching treatment to remove the first second doped layer exposed from the first oxide layer. Before forming the first electrode and the second electrode, the method further includes a step of removing the second oxide layer.

[0024] In some embodiments, in the second wet etching process, the film layer on the surface of the first doped layer is also removed. The process time of the second wet etching treatment is 300s to 800s, and the process temperature of the second wet etching is 60°C to 80°C.

[0025] According to some embodiments of the present disclosure, an embodiment of the present disclosure is a photovoltaic module including a plurality of electrically connected cell strings, a sealing adhesive film for covering the surface of the cell string, and a cover for covering the surface of the sealing adhesive film away from the cell string, where the cell string is a solar cell described in the above embodiment or a solar cell formed by the manufacturing method of the solar cell described in the above embodiment.

Advantages of the Invention

[0026] The technical means provided by the embodiments of the present disclosure have at least the following advantages.

[0027] The solar cell provided by the embodiments of the present disclosure includes a substrate having opposite front and back surfaces, a first doped layer and a second doped layer alternately arranged along a first direction on the back surface, where the first doped layer and the second doped layer adjacent to it are separated by a separation region, the doping type of the first doped layer is different from that of the second doped layer, a part of the back surface is exposed by the separation region, the side wall of the first doped layer facing the separation region is a first inclined side wall, and the side wall of the second doped layer facing the separation region is a second inclined side wall, the first doped layer and the second doped layer, a first electrode in electrical contact with the first doped region, and a second electrode in electrical contact with the second doped region. In a related IBC cell, the back surface of the substrate is provided with a first doped layer and a second doped layer alternately arranged along the first direction, the doping types of the first doped layer and the second doped layer are different, and the first doped layer and the second doped layer adjacent to it are separated by a separation region. However, the side wall of the first doped layer facing the separation region is a normal vertical side wall, and the side wall of the second doped layer facing the separation region is also a normal vertical side wall. As a result, a large amount of the light incident on the solar cell is reflected, the utilization rate of the solar cell for light is reduced, and the efficiency of the cell is affected. In the solar cell provided by the embodiments of the present disclosure, the side wall between the separation region adjacent to the first doped region on the back surface of the cell is a first inclined side wall, and the side wall between the separation region adjacent to the second doped region is a second inclined side wall. The first inclined side wall and the second inclined side wall can improve the reflection of the incident light, thereby improving the utilization rate of the light by the solar cell and can improve the efficiency of the cell.

Brief Description of the Drawings

[0028] One or more embodiments are exemplarily illustrated by images in the corresponding drawings. These exemplary descriptions do not constitute limitations on the embodiments unless otherwise specified, and the images in the drawings do not constitute scale limitations. To more clearly explain the embodiments of the present disclosure or the technical means in the prior art, the drawings used in the embodiments are briefly described. The accompanying drawings are only some embodiments of the present disclosure, and it is obvious that those skilled in the art can obtain other drawings from these drawings without inventive efforts.

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Embodiments for Carrying Out the Invention

[0029] From the background art, it can be seen that there is a problem that the current solar cells have room to improve the utilization rate for light.

[0030] Embodiments of the present disclosure provide a solar cell including a substrate, and a first doped layer and a second doped layer alternately arranged along a first direction on the back surface of the substrate. The second doped layer adjacent to the first doped layer is separated by a separation region. The doping type of the first doped layer is different from the doping type of the second doped layer. A part of the back surface is exposed by the separation region. The side wall of the first doped layer facing the separation region becomes a first inclined side wall, and the side wall of the second doped layer facing the separation region becomes a second inclined side wall. The first electrode is in electrical contact with the first doped layer, and the second electrode is in electrical contact with the second doped layer. In this way, the reflection of incident light can be improved by the first inclined side wall and the second inclined side wall, and the utilization rate of light by the solar cell can be improved to improve the efficiency of the cell.

[0031] To make the objectives, technical means and advantages of the embodiments of the present invention clearer, the following will describe each embodiment of the present disclosure in detail with reference to the drawings. However, in each embodiment of the present disclosure, although many technical details are presented so that readers can better understand the present disclosure, those skilled in the art can understand that the technical means claimed by the present disclosure can be realized even without these technical details and various changes and modifications based on the following embodiments.

[0032] FIG. 1 is a schematic structural diagram of a solar cell provided by an embodiment of the present disclosure. FIG. 2 is a schematic top view structural diagram of the solar cell shown in FIG. 1.

[0033] Referring to FIGS. 1 to 2, the solar cell includes a substrate 100 having opposite front surface 101 and back surface 102, and a first doped layer 110 and a second doped layer 120 alternately arranged along a first direction X on the back surface 102. A separation region 103 separates the first doped layer 110 from the second doped layer 120 adjacent thereto. The doping type of the first doped layer 110 is different from that of the second doped layer 120. A part of the back surface 102 is exposed by the separation region 103. The side wall of the first doped layer 110 facing the separation region 103 is a first inclined side wall 111, and the side wall of the second doped layer 120 facing the separation region 103 is a second inclined side wall 121. The solar cell further includes a first electrode 130 in electrical contact with the first doped layer 110 and a second electrode 140 in electrical contact with the second doped layer 120.

[0034] In related technologies, the back surface of the IBC cell substrate is provided with a first doped layer and a second doped layer that are alternately arranged along a first direction and have different doping types, and the first doped layer and the second doped layer adjacent thereto are separated by a separation region. However, the side wall of the first doped layer facing the separation region is a normal vertical side wall, and the side wall of the second doped layer facing the separation region is also a normal vertical side wall. As a result, a large amount of the light incident on the solar cell is reflected. When the incident light irradiates the normal vertical side wall, it is reflected outside the cell instead of being reflected inside the cell, becoming unavailable. This reduces the utilization rate of the light by the solar cell and affects the efficiency of the cell.

[0035] In an embodiment of the present disclosure, the side wall facing the separation region 103 of the first doped layer 110 is defined as the first inclined side wall 111, and the side wall facing the separation region 103 of the second doped layer 120 is defined as the second inclined side wall 121. When incident light irradiates the first inclined side wall 111 or the second inclined side wall 121, it is reflected inside the battery and utilized, and can be converted into electrical energy. That is, the first inclined side wall 111 and the second inclined side wall 121 can enhance the reflection of incident light, improve the utilization rate of the solar cell for light, and improve the efficiency of the battery. In addition, the first inclined side wall 111 and the second inclined side wall 121 can increase the optical path length inside the battery and improve the current density of the solar cell.

[0036] Note that a plurality of the first doped layer 110, the second doped layer 120, and the separation region 103 may be provided in the battery. Only one first doped layer 110, one second doped layer 120, and one separation region 103 are shown in the drawings.

[0037] In some embodiments, the solar cell may be an IBC cell (Interdigitated Back Contact cell).

[0038] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element such as silicon or germanium, for example. Here, the elemental semiconductor material may be in a single crystal state, a polycrystalline state, an amorphous state, or a 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.

[0039] In some embodiments, the material of the substrate 100 may be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, materials such as silicon germanide, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, and copper indium selenide. The substrate 100 may be a sapphire substrate, a silicon-on-insulator substrate, or a germanium-on-insulator substrate.

[0040] In some embodiments, the substrate 100 may be an N-type semiconductor substrate 100 or a P-type semiconductor substrate 100. The N-type semiconductor substrate 100 is doped with an N-type dopant element, and the N-type dopant element may be any of Group V elements such as phosphorus (P) element, bismuth (Bi) element, antimony (Sb) element, or arsenic (As) element. The P-type semiconductor substrate 100 is doped with a P-type element, and the P-type dopant element may be any of Group III elements such as boron (B) element, aluminum (Al) element, gallium (Ga) element, or indium (In) element.

[0041] In some embodiments, the dopant ions in the first doped layer 110 may include P-type dopant elements, such as boron ions, and the dopant ions in the second doped layer 120 may include N-type dopant elements, such as phosphorus ions. When the substrate 100 is an N-type substrate, the doping type of the first doped layer 110 is different from that of the substrate 100, and the doping type of the second doped layer 120 is the same as that of the substrate 100. At this time, a p-n junction is formed by the first doped layer 110 and the substrate 100, and the first doped layer 110 can function as the emitter of the solar cell. When the substrate 100 is a P-type substrate, the doping type of the first doped layer 110 is the same as that of the substrate 100, and the doping type of the second doped layer 120 is different from that of the substrate 100. At this time, a p-n junction is formed by the second doped layer 120 and the substrate 100, and the second doped layer 120 can function as the emitter of the solar cell. Since the first doped layer 110 and the second doped layer 120 having different doping types are both disposed on the back surface 102 of the substrate 100, the occupied area of the electrode with respect to the front surface 101 of the substrate 100 can be reduced, and the shielding by the gate line on the surface of the battery can be eliminated. As a result, the light-shielding current loss of the metal electrode is eliminated, and the maximum utilization of incident photons is realized. Moreover, since there is no need to consider the problem of shielding by the gate line, the proportion of the gate line can be appropriately increased, thereby reducing the series resistance and having a high fill factor.

[0042] Referring to FIG. 3, in some embodiments, the angle between the first inclined sidewall 111 and the surface facing the back surface 102 of the first doped layer 110 may be an acute first angle a. The angle between the second inclined sidewall 121 and the surface facing the back surface 102 of the second doped layer 120 may be an acute second angle b. When the first angle a and the second angle b are acute angles, the first inclined sidewall 111 protrudes in the direction of the separation region 103 with respect to the first doped layer 110, and the second inclined sidewall 121 protrudes in the direction of the separation region 103 with respect to the second doped layer 120. In this way, the first inclined sidewall 111 and the second inclined sidewall 121 can improve the reflection of incident light, improve the light utilization rate of the solar cell, and improve the efficiency of the cell.

[0043] In some embodiments, the first angle a may be less than or equal to the second angle b. When the first angle a is smaller than the second angle b, the first inclined sidewall 111 and the second inclined sidewall 121 can have different gradients, and the gradient of the first inclined sidewall 111 is smaller than the gradient of the second inclined sidewall 121, so that the first inclined sidewall 111 and the second inclined sidewall 121 can reflect different incident lights and reflect incident lights at different angles into the cell for reuse, further improving the light utilization rate of the solar cell.

[0044] In the manufacturing process of the solar cell, the etching time of the first inclined sidewall 111 corresponding to the first doped layer 110 is longer than the etching time of the second inclined sidewall 121 corresponding to the second doped layer 120. Thereby, the gradient of the first inclined sidewall 111 can be made smaller than the gradient of the second inclined sidewall 121, and the first angle a can be made less than or equal to the second angle b.

[0045] In some embodiments, the first angle a may be in the range of 25° to 60°, and the second angle b may be in the range of 30° to 65°. For example, the first angle a may be 25°, 30°, 45°, 60°, etc., and the second angle b may be 30°, 45°, 60°, 65°, etc. It can be appropriate. If the magnitude of the first angle a is too large or too small, the gradient strength of the first inclined sidewall 111 will be low, and the first inclined sidewall 111 will tend to be perpendicular to the sidewall. The reflection effect of the first inclined sidewall 111 on the incident light is poor, and it will be difficult to effectively improve the light utilization rate of the battery. If the magnitude of the second angle b is too large or too small, the gradient strength of the second inclined sidewall 121 will be low, and the second inclined sidewall 121 will tend to be perpendicular to the sidewall. The reflection effect of the second inclined sidewall 121 on the incident light is poor, and similarly, it will be difficult to effectively improve the light utilization rate of the battery. Therefore, it is necessary to select an appropriate range for the first angle a and the second angle b. When the first angle a is 25° - 60° and the second angle b is 30° - 65°, the light utilization rate of the battery can be effectively improved, and the efficiency of the battery can be improved.

[0046] Referring to FIG. 4, in some embodiments, the first inclined sidewall 111 may include a first sub-inclined sidewall 1111, a platform surface 1112, and a second sub-inclined sidewall 1113 that are sequentially connected in a direction away from the back surface 102 of the substrate 100. Note that the platform surface 1112 may be parallel to the back surface of the substrate 100 or may have a certain gradient. In this way, the reflection of the incident light on the battery can be increased by the first sub-inclined sidewall 1111, the second sub-inclined sidewall 1113, and the platform surface 1112 located on different planes, and the light utilization rate of the solar cell can be further improved, and the battery efficiency can be further improved. In addition, the first sub-inclined sidewall 1111, the platform surface 1112, and the second sub-inclined sidewall 1113 can also further scatter the light incident on the battery, thereby making the optical path length in the battery longer and the current density of the solar cell higher.

[0047] In some embodiments, in a direction perpendicular to the back surface 102 of the substrate 100, the distance between the surface of the first doped layer 110 on the side away from the substrate 100 and the front surface 101 of the substrate 100 may be greater than the distance between the surface of the second doped layer 120 on the side away from the substrate 100 and the front surface 101 of the substrate 100. Here, the platform surface 1112 is closer to the back surface 102 than the surface of the second doped layer 120 on the side away from the substrate 100. In the manufacture of a solar cell, if the distance between the surface of the first doped layer 110 on the side away from the substrate 100 and the front surface 101 of the substrate 100 is made greater than the distance between the surface of the second doped layer 120 on the side away from the substrate 100 and the front surface 101 of the substrate 100, the unpatterned second doped layer 120 can cover a part of the thickness of the first inclined sidewall 111. As a result, when the separation region 103 is patterned to expose the back surface 102 of the substrate 100, the portion of the first inclined sidewall 111 exposed from the second doped layer 120 has a longer etching time than the portion of the first inclined sidewall 111 covered by the second doped layer 120. Thereby, after the patterning is completed, the first inclined sidewall 111 including the first sub-inclined sidewall 1111, the platform surface 1112, and the second sub-inclined sidewall 1113 can be formed. The reflection of the incident light of the battery can be increased by each of the first sub-inclined sidewall 1111, the second sub-inclined sidewall 1113, and the platform surface 1112 in different planes, and the light utilization rate of the solar cell can be further improved to further improve the battery efficiency.

[0048] Note that when manufacturing a solar cell, when patterning the second doped layer 120 of the separation region 103 to expose the back surface 102 of the substrate 100, the platform surface 1112, which was originally flush with the surface of the second doped layer 120 on the side away from the substrate 100, will also be etched. Therefore, the platform surface 1112 is closer to the back surface 102 than the surface of the second doped layer 120 on the side away from the substrate 100.

[0049] In other embodiments, the distance between the platform surface 1112 and the back surface 102 of the substrate 100 may be the same as the distance between the surface of the second doped layer 120 away from the substrate 100 and the back surface 102.

[0050] Continuing to refer to FIG. 4, in some embodiments, perpendicular to the back surface 102 of the substrate 100 In the direction, the thickness of the second sub-inclined sidewall 1113 may be smaller than the thickness of the first sub-inclined sidewall 1111. When forming the first sub-inclined sidewall 1111 and the second sub-inclined sidewall 1113, since the etching direction of the etching process is the direction approaching the substrate 100, the etching time experienced by the first sub-inclined sidewall 1111 closer to the substrate 100 is shorter than that of the second sub-inclined sidewall 1113 away from the substrate 100. Therefore, the thickness of the etched first sub-inclined sidewall 1111 is smaller than the thickness of the etched second sub-inclined sidewall 1113, and the thickness of the finally formed second sub-inclined sidewall 1113 may be smaller than the thickness of the first sub-inclined sidewall 1111. In this way, the first sub-inclined sidewall 1111 and the second sub-inclined sidewall 1113 can be made not to be on the same plane, and the first sub-inclined sidewall 1111 and the second sub-inclined sidewall 1113 can reflect incident light at different angles to increase the utilization rate of the incident light, further improving the light utilization rate of the battery and improving the efficiency of the battery.

[0051] In other embodiments, in the direction perpendicular to the back surface 102 of the substrate 100, the thickness of the second sub-inclined sidewall 1113 may be equal to or greater than the thickness of the first sub-inclined sidewall 1111.

[0052] Referring to FIG. 5, in some embodiments, with respect to the back surface 102, the gradient of the second sub-inclined sidewall 1113 may be greater than the gradient of the first sub-inclined sidewall 1111. That is, the second sub-inclined sidewall 1113 is closer to being perpendicular than the first sub-inclined sidewall 1111. When forming the first sub-inclined sidewall 1111 and the second sub-inclined sidewall 1113, etching is performed with an etching solution in a direction approaching the substrate 100 from the side away from the substrate 100. Therefore, the etching time of the second sub-inclined sidewall 1113 closer to the outside is longer than that of the first sub-inclined sidewall 1111 closer to the substrate 100. Accordingly, with respect to the back surface 102, the gradient of the second sub-inclined sidewall 1113 may be greater than the gradient of the first sub-inclined sidewall 1111. Thus, since the first sub-inclined sidewall 1111 and the second sub-inclined sidewall 1113 have different inclinations, the first sub-inclined sidewall 1111 and the second sub-inclined sidewall 1113 can reflect incident light at different angles to increase the utilization rate of the incident light, further improving the light utilization rate of the battery and thus improving the efficiency of the battery.

[0053] In other embodiments, with respect to the back surface 102, the gradient of the second sub-inclined sidewall 1113 and the gradient of the first sub-inclined sidewall 1111 may be the same.

[0054] Referring to FIG. 6, in some embodiments, in the direction perpendicular to the back surface 102 of the substrate 100, the distance between the surface of the first doped layer 110 on the side away from the substrate 100 and the front surface 101 of the substrate 100 may be less than or equal to the distance between the surface of the second doped layer 120 on the side away from the substrate 100 and the front surface 101 of the substrate 100. That is, the surface of the second doped layer 120 on the side away from the substrate 100 protrudes in the direction away from the substrate 100 with respect to the surface of the first doped layer 110 on the side away from the substrate 100, or the surface of the second doped layer 120 on the side away from the substrate 100 is flush with the surface of the first doped layer 110 on the side away from the substrate 100.

[0055] Note that the distance between the surface of the first doped layer 110 on the side away from the substrate 100 and the front surface 101 of the substrate 100 being less than or equal to the distance between the surface of the second doped layer 120 on the side away from the substrate 100 and the front surface 101 of the substrate 100 does not necessarily mean that the thickness of the first doped layer 110 is less than or equal to the thickness of the second doped layer 120. When forming the first doped layer 110 and the second doped layer 120, there may be some overetching. Therefore, a part of the back surface 102 of the substrate 100 corresponding to the first doped layer 110 and a part of the back surface 102 of the substrate 100 corresponding to the second doped layer 120 are not necessarily on the same plane. Thus, the relationship between the surface of the first doped layer 110 on the side away from the substrate 100 and the surface of the second doped layer 120 on the side away from the substrate 100 cannot be explained solely by the thickness relationship. Also, referring to FIGS. 4 to 6, when forming the first doped layer 110 and the second doped layer 120 and causing overetching with respect to the substrate 100, a part of the side wall of the substrate 100 adjacent to the inclined side wall of the first doped layer 110 may be inclined. When forming and causing overetching with respect to the substrate 100, a part of the side wall of the substrate 100 adjacent to the inclined side wall of the first doped layer 110 may be inclined.

[0056] Continuing to refer to FIG. 6, in some embodiments, the first inclined sidewall 111 may be a continuous inclination. In the process of forming the first doped layer 110 and the second doped layer 120, the distance between the surface of the second doped layer 120 on the side away from the substrate 100 and the front surface 101 of the substrate 100 is greater than or equal to the distance between the surface of the first doped layer 110 on the side away from the substrate 100 and the front surface 101 of the substrate 100. Before patterning, the second doped layer 120 can cover all of the first inclined sidewall 111. Therefore, the first inclined sidewall 111 only undergoes an etching process once when the second doped layer 120 is patterned, and the first inclined sidewall 111 does not become a discontinuous inclination, and the finally formed first inclined sidewall 111 can still be a continuous inclination. After forming the first doped layer 110 and the second doped layer 120, a second passivation layer 180 covering the first doped layer 110 and the second doped layer 120 can also be formed on the back surface 102 of the substrate 100. Therefore, making the first inclined sidewall 111 a continuous inclination is also advantageous for the formation of the second passivation layer 180, facilitating the deposition of the second passivation layer 180, reducing the deposition difficulty of the second passivation layer 180, reducing the production difficulty, and improving the production efficiency.

[0057] In some embodiments, the second inclined sidewall 121 may be a continuous inclination. The second inclined sidewall 121 is the inclined sidewall left when the second doped layer 120 is patterned. Since the second inclined sidewall 121 only undergoes a continuous etching process once, the second inclined sidewall 121 can be a continuous inclination.

[0058] Referring to FIG. 7, in some embodiments, the back surface 102 exposed by the separation region 103 may have a pile structure 104, and the pile structure 104 may include a plurality of pyramid structures. While patterning the second doped layer 120 so that the back surface 102 of the substrate 100 in the separation region 103 is exposed, at the same time, a pile processing treatment can be performed on the back surface 102 exposed in the separation region 103 so that the back surface 102 exposed in the separation region 103 has a pile structure by the etching atmosphere. In this way, the pile structure can reflect incident light so that a part of the incident light can be reflected and reused inside the battery, further improving the light utilization rate of the battery and improving the efficiency of the battery. In addition, since the back surface 102 exposed in the separation region 103 has a pile structure, the light incident on the battery can be further scattered, thereby making the optical path length in the battery longer and the current density of the solar cell higher.

[0059] In some embodiments, the width of the bottom surface of one pyramid structure may be 2 μm to 4 μm in the direction parallel to the back surface 102. For example, the width of the bottom surface of one pyramid structure may be 2 μm, 3 μm, 4 μm, etc. in the direction parallel to the back surface 102. Note that the width of the bottom surface of the pyramid structure is the maximum width of the bottom surface of the pyramid structure in any direction parallel to the back surface 102. In the direction parallel to the back surface 102, if the width of the bottom surface of the pyramid structure is too large, the number of pyramids in the separation region 103 is too small, the effect of improving the reflection of incident light by the pile structure is poor, the light utilization rate of the battery is still low, and there is still room for improving the efficiency of the battery. If the width of the bottom surface of the pyramid structure is too small, the height of the pyramid structure also becomes correspondingly small, the effect of improving the reflection of incident light by the pile structure is still poor, the light utilization rate of the battery is still low, and there is still room for improving the efficiency of the battery. Therefore, it is necessary to select the width of the bottom surface of the pyramid structure in the direction parallel to the back surface 102 within an appropriate range. When the width of the bottom surface of one pyramid structure is 2 μm to 4 μm, the effect of improving the reflection of incident light by the pile structure is good, the light utilization efficiency of the battery can be effectively improved, and the efficiency of the battery can be effectively improved.

[0060] In the pile structure shown in FIG. 7, the dimensions of each pyramid structure are the same. However, in an actual pile structure, the dimensions of each pyramid structure may be different. Specifically, the width in the direction parallel to the back surface 102 of each pyramid structure and the height of each pyramid structure may be different.

[0061] Referring to FIG. 8, in some embodiments, the substrate 100 may be subjected to a pile processing treatment such that a pile is formed on the front surface of the substrate 100, thereby improving the absorption utilization rate of the light by the substrate 100. In some embodiments, the pile may be a pyramid pile. As a general pile, the pyramid pile not only reduces the reflectivity of the surface of the substrate 100, but also forms an optical trap to enhance the absorption effect of the light by the substrate 100, and can increase the conversion efficiency of the solar cell.

[0062] In some embodiments, the solar cell may further include a first tunnel layer 150 and a second tunnel layer 160. The first tunnel layer 150 is disposed between the first doped layer 110 and the substrate 100, and the second tunnel layer 160 is disposed between the second doped layer 120 and the substrate 100. The first tunnel layer 150 and the second tunnel layer 160 allow a large number of carriers to tunnel into the doped layer while blocking the passage of minority carriers. As a result, a large number of carriers are transported laterally in the doped layer and collected by the electrodes, reducing the carrier recombination and increasing the open-circuit voltage and short-circuit current of the battery. At this time, the tunnel oxide layer and the doped layer constitute a tunnel oxidation passivation contact structure, which can achieve excellent interface passivation and selective collection of carriers, and improve the photoelectric conversion efficiency of the back contact battery.

[0063] In addition, when forming the first doped layer 110 and the second doped layer 120 and causing overetching on the substrate 100, the side wall of the first tunnel layer 150 adjacent to the inclined side wall of the first doped layer 110 may be inclined, a part of the side wall of the substrate 100 adjacent to the inclined side wall of the first tunnel layer 150 may be inclined, and the side wall of the second tunnel layer 160 adjacent to the second doped layer 120 may be inclined.

[0064] In some embodiments, the material of the first tunnel layer 150 can include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride. The material of the second tunnel layer 160 can include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride.

[0065] In some embodiments, the solar cell may further include a first passivation layer 170 disposed on the front surface 101 of the substrate 100 and a second passivation layer 180 disposed on the back surface 102 of the substrate 100. Here, the first passivation layer 170 covers the surface of the front surface 101 of the substrate 100, and the second passivation layer 180 may cover the back surface 102 of the substrate 100 and the surfaces of the first doped layer 110 and the second doped layer 120 located on the back surface 102 of the substrate 100. The electrodes of the solar cell penetrate through the second passivation layer 180 and are in electrical contact with the first doped layer 110 or the second doped layer 120.

[0066] The first passivation layer 170 can exert a good passivation effect on the front surface 101 of the substrate 100, reduce the defect level density of the front surface 101 of the substrate 100, and can preferably suppress the carrier recombination of the front surface 101 of the substrate 100. In addition, the first passivation layer 170 can exert a good antireflection effect, reduce the reflection of the incident light by the front surface 101 of the substrate 100, and can improve the utilization rate of the incident light by the substrate 100. The second passivation layer 180 can exert a good passivation effect on the back surface 102 of the substrate 100. For example, it can perform good chemical passivation on the dangling bonds of the back surface 102 of the substrate 100, saturate the dangling bonds of the back surface 102 of the substrate 100, reduce the defect level density of the back surface 102 of the substrate 100, and can suppress the carrier recombination of the back surface of the substrate 100.

[0067] In some embodiments, the material of the first passivation layer 170 can include one of silicon nitride, aluminum oxide, silicon nitride, or silicon oxynitride. The material of the second passivation layer 180 can include at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0068] In some embodiments, the first passivation layer 170 may have a single-layer structure or a multilayer structure. In the case of a multilayer structure, 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 first passivation layer 170 may have a multilayer structure of a silicon nitride layer and an aluminum oxide layer. In some embodiments, the second passivation layer 180 may have a single-layer structure. In some embodiments, the second passivation layer 180 may have a multilayer structure, and the materials of each layer of the multilayer structure may be different from each other, or the materials of some layers may be different from each other and the materials of other parts may be the same. For example, the second passivation layer 180 may have a multilayer structure of a silicon nitride layer and an aluminum oxide layer.

[0069] When the second passivation layer 180 includes an aluminum oxide layer, first, a groove formation process using a laser beam may be performed, and then a screen printing process may be performed to ensure that the first electrode 130 is in electrical contact with the first doped layer 110 and the second electrode 140 is in electrical contact with the second doped layer 120.

[0070] In some embodiments, the first electrode 130 and the second electrode 140 may be sintered from a fire-through type paste. The method of forming the first electrode 130 and the second electrode 140 may include printing a metal paste by a screen printing process. The metal paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0071] In some embodiments, the width of the first doped layer 110 in the first direction X may be greater than the width of the second doped layer 120 in the first direction X, and correspondingly, the width of the first electrode 130 in electrical contact with the first doped layer 110 in the first direction X may be greater than the width of the second electrode 140 in electrical contact with the second doped layer 120 in the first direction X. In this way, the first electrode 130 having a large width in the first direction X can collect carriers better and improve the current transmission effect of the solar cell.

[0072] In some embodiments, the metal paste contains materials of highly corrosive components such as glass. As a result, during sintering, the corrosive components corrode some of the film layers of the battery, causing the metal paste to penetrate into some regions of the battery. Embodiments of the present disclosure provide a solar cell including a substrate and a first doped layer and a second doped layer that are disposed on the back surface of the substrate and alternately arranged along a first direction. The second doped layer adjacent to the first doped layer is separated by a separation region. The doping type of the first doped layer is different from that of the second doped layer. A part of the back surface is exposed by the separation region. The side wall of the first doped layer facing the separation region is a first inclined side wall, and the side wall of the second doped layer facing the separation region is a second inclined side wall. The first electrode is in electrical contact with the first doped layer, and the second doped layer is in electrical contact with the second electrode. In this way, the first inclined side wall and the second inclined side wall can improve the reflection of incident light, improve the utilization rate of light by the solar cell, and improve the efficiency of the battery.

[0073] Correspondingly, other embodiments of the present disclosure also provide a method for manufacturing a solar cell that can be used to manufacture the solar cell described in the above embodiments. Hereinafter, the solar cell provided by other embodiments of the present disclosure will be described in detail with reference to the drawings. However, for the same or corresponding parts as those in the foregoing embodiments, reference may be made to the corresponding descriptions in the foregoing embodiments, and the following will not be repeatedly described in detail. For the same or corresponding parts, reference may be made to the corresponding descriptions in the foregoing embodiments, and the following will not be repeatedly described in detail.

[0074] Referring to FIG. 9, a substrate 100 having opposite front surface 101 and back surface 102 is provided.

[0075] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element such as silicon or germanium, for example. Here, the elemental semiconductor material may be in a single crystal state, a polycrystalline state, an amorphous state, or a 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.

[0076] In some embodiments, the material of the substrate 100 may be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, materials such as silicon germanide, silicon carbide, gallium arsenide, indium gallium arsenide, perovskite, cadmium telluride, and copper indium selenide. The substrate 100 may be a sapphire substrate, a silicon-on-insulator substrate, or a germanium-on-insulator substrate.

[0077] In some embodiments, the substrate 100 may be an N-type semiconductor substrate 100 or a P-type semiconductor substrate 100. The N-type semiconductor substrate 100 is doped with an N-type dopant element, and the N-type dopant element may be any of Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate 100 is doped with a P-type element, and the P-type dopant element may be any of Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0078] Referring to FIG. 10, a first first-doped layer 210 is formed on the back surface 102 of the substrate 100.

[0079] Specifically, the substrate 100 can be placed in a diffusion furnace, and the first first-doped layer 210 can be formed by diffusion doping. The process temperature of the diffusion doping may be 800°C to 1200°C, and the process time of the diffusion doping may be 2 hours to 5 hours. For example, the process temperature of the diffusion doping may be 800°C, 1000°C, 1100°C, 1200°C, etc., and the process time of the diffusion doping may be 2 hours, 3 hours, 4 hours, 5 hours, etc.

[0080] In some embodiments, the first first-doped layer 210 may be doped with boron ions.

[0081] In some embodiments, before forming the first first doped layer 210, a first first tunnel layer 250 covering the back surface 102 of the substrate 100 may be formed on the back surface 102 of the substrate 100, and the first first doped layer 210 covers the surface of the first first tunnel layer 250 that is away from the substrate 100.

[0082] In some embodiments, when forming the first first doped layer 210, a first first oxide layer 10 may be formed on the surface of the first first doped layer 210. The first first oxide layer 10 may be borosilicate glass (BSG). The thickness of the first first oxide layer 10 may be 100 nm to 200 nm. For example, the thickness of the first first oxide layer 10 may be 100 nm, 150 nm, 200 nm, etc.

[0083] Referring to FIG. 11, a first patterning process is performed on the first first doped layer 210 to form a plurality of first doped layers 110 arranged at intervals in the first direction X. The sidewalls of the first doped layers 110 become the first first inclined sidewalls 211.

[0084] Note that the width of the first doped layer 110 formed by the first patterning process in the first direction X may be 400 nm to 800 nm. For example, the width of the first doped layer 110 in the first direction X may be 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, etc.

[0085] In some embodiments, a part of the substrate 100 may be removed in the first patterning process, whereby the thickness of the part of the substrate 100 covered by the first doped layer 110 is slightly larger than the thickness of the part of the substrate 100 not covered by the first doped layer 110.

[0086] In some embodiments, the process of the first patterning process may include a step of patterning the first oxide layer 10 by the first laser light treatment to form the first oxide layer 11 on the surface of the first doped layer 110 away from the substrate 100. In the first laser light treatment, an inclination is not formed on the sidewalls of the first oxide layer 11, and the sidewalls of the first oxide layer 11 are vertical sidewalls.

[0087] Note that patterning the first doped layer 210 initially by the laser light treatment process will modify the first doped layer 110 and affect the normal performance of the battery. Therefore, the laser light treatment process should only pattern the first oxide layer 10 initially and should not pattern the first doped layer 210.

[0088] In some embodiments, the laser power of the first laser light treatment may be 20W to 30W. For example, the power of the first laser light treatment may be 20W, 25W, 30W, etc. If the power of the first laser light treatment is too high, it will not only cause waste of energy and increase production costs, but also may modify the first doped layer 110 and affect the performance of the battery. If the power of the first laser light treatment is too low, the efficiency of patterning the first oxide layer 10 will be too low. Therefore, it is necessary to select an appropriate range for the power of the first laser light treatment. When the laser power of the first laser light treatment is 20W to 30W, it is possible to improve production efficiency while avoiding modification of the first doped layer without increasing production costs.

[0089] In some embodiments, the width of the first laser light treatment region in the first direction X may be 300μm to 600μm. For example, the width of the first laser light treatment region in the first direction X may be 300μm, 400μm, 500μm, 600μm, etc. The depth of the first laser light treatment region may be 3μm to 6μm. For example, the depth of the first laser light treatment region may be 3μm, 4μm, 5μm, 6μm, etc.

[0090] In some embodiments, following the first laser light treatment, the first doped layer 210 exposed from the first oxide layer 11 can be removed by a first wet etching process, and in the first wet etching process, the surface damage caused by the laser light treatment process can also be removed. If the first first tunnel layer 250 was formed in the previous step, it is also necessary to etch the first first tunnel layer 250 by the first wet etching process, and the remaining first first tunnel layer 250 is used as the first tunnel layer 150. Specifically, a wet etching treatment may be performed using an NaOH solution to wet etch the first doped layer 210, and the remaining first doped layer 210 may be used as the first doped layer 110. After patterning the first doped layer 210, the first first tunnel layer 250 may be etched with an acidic solution to form the first tunnel layer 150. In the first wet etching process, a first first inclined sidewall 211 can be formed on the sidewall facing the separation region 103 of the first doped layer 110.

[0091] In some embodiments, the concentration of the NaOH solution for etching the first doped layer may be 1% to 5%. For example, the concentration of the NaOH solution for etching the first doped layer may be 1%, 2%, 3%, 4%, 5%, etc.

[0092] In some embodiments, the process time of the first wet etching process may be 500 s to 1000 s. For example, the process time of the first wet etching process may be 500 s, 600 s, 700 s, 800 s, 900 s, 1000 s, etc. If the process time of the first wet etching process is too long, it may cause excessive over-etching on the substrate 100 and affect the structure of the battery. If the process time of the first wet etching is too short, the first first doping layer 210 and the first first tunnel layer 250 in other regions may not be completely removed, which may affect the normal performance of the battery. Therefore, it is necessary to select an appropriate range for the process time of the first wet etching process. When the process time of the first wet etching process is 500 s to 1000 s, the first first doping layer 210 and the first first tunnel layer 250 in other regions can be removed, and excessive over-etching on the substrate 100 can also be avoided.

[0093] In addition, when patterning the first first oxide layer 10 by the laser light treatment process, it is not necessary to form a patterning mask layer on the first first oxide layer 10, so the process flow can be simplified and the production efficiency can be improved. After patterning the first first oxide layer 10 by laser light treatment, the remaining first first oxide layer 10 is used as the first oxide layer 11. At this time, the first oxide layer 11 can be used as a patterning mask layer. In the first wet etching process, the first first doping layer 210 is etched using the first oxide layer 11 as a mask, and the remaining first first doping layer 210 can be used as the first doping layer 110. Such a process step is to first pattern the oxide layer formed in the doping process by laser light treatment, and the patterned oxide layer can be directly used as the etching mask layer in the next step. Thereby, the process steps of forming and removing the mask layer can be avoided, the process flow can be simplified, the production efficiency can be improved, and the production cost can also be reduced.

[0094] Referring to FIG. 12, on the back surface 102 of the substrate 100, a first second doped layer 220 having a doping type different from that of the first doped layer 110 is formed.

[0095] Specifically, the substrate 100 can be placed in a diffusion furnace, and the first second doped layer 220 can be formed by diffusion doping. The process temperature of the diffusion doping may be 700°C to 1000°C, and the process time of the diffusion doping may be 1 hour to 3 hours. For example, the process temperature of the diffusion doping may be 700°C, 800°C, 900°C, 1000°C, etc., and the process time of the diffusion doping may be 1 hour, 2 hours, 3 hours, etc.

[0096] In some embodiments, the first second doped layer 220 may be doped with phosphorus ions.

[0097] In some embodiments, before forming the first second doped layer 220, a first second tunnel layer 260 covering at least a part of the back surface 102 of the substrate 100 may be formed on the back surface 102 of the substrate 100, and the first second doped layer 220 covers the surface of the first second tunnel layer 260 away from the substrate 100.

[0098] In some embodiments, in the step of forming the first second doped layer 220, the first second doped layer 220 is also disposed on the surface of the first doped layer 110, and a first second oxide layer 20 is also formed on the surface of the first second doped layer 220. The first second oxide layer 20 may be phosphosilicate glass (BSG). The thickness of the first second oxide layer 20 may be 100 nm to 200 nm. For example, the thickness of the first second oxide layer 20 may be 100 nm, 150 nm, 200 nm.

[0099] Referring to FIGS. 13 to 14, a second patterning process is performed on the first second doped layer 220 to form the second doped layer 120. The first doped layer 110 and the second doped layer 120 are alternately arranged along the first direction X on the back surface 102 of the substrate 100. A separation region 103 separates the first doped layer 110 and the adjacent second doped layer 120, and a part of the back surface 102 is exposed by the separation region 103. Here, the first inclined sidewall 211 after the second patterning process becomes the first inclined sidewall 111. The first inclined sidewall 111 is a sidewall facing the separation region 103 of the first doped layer 110, and the sidewall facing the separation region 103 of the second doped layer 120 is the second inclined sidewall 121.

[0100] In some embodiments, referring to FIG. 13, the second patterning process may include performing a second laser light treatment to pattern the first second oxide layer 20 to form a second oxide layer 21 that exposes at least the first second doped layer 220 corresponding to the separation region 103. In the second laser light treatment, an inclination is not formed on the sidewall of the second oxide layer 21, and the sidewall of the second oxide layer 21 becomes a vertical sidewall.

[0101] Note that patterning the first second doped layer 220 by the laser light treatment process will modify the second doped layer 120 and affect the normal performance of the battery. Therefore, the laser light treatment process should only pattern the first second oxide layer 20 and not pattern the first second doped layer 220.

[0102] Also, if the first second oxide layer 20 formed in the previous process remains on the first doped layer 110, the first second oxide layer 20 on the first doped layer 110 can also be removed by the second laser light treatment.

[0103] In some embodiments, the laser power of the second laser light treatment may be 20W to 30W. For example, the power of the second laser light treatment may be 20W, 25W, 30W, etc. If the power of the second laser light treatment is too high, it will not only cause waste of energy and increase production costs, but also may modify the second doped layer 120 and affect the performance of the battery. If the power of the second laser light treatment is too low, the efficiency of patterning the initial second oxide layer 20 will be too low. Therefore, it is necessary to select an appropriate range for the power of the second laser light treatment. When the laser power of the second laser light treatment is 20W to 30W, it is possible to improve the production efficiency while avoiding modification of the second doped layer without increasing the production cost.

[0104] In some embodiments, the width of the second laser light treatment region in the first direction X may be 400μm to 700μm. For example, the width of the second laser light treatment region in the first direction X may be 400μm, 500μm, 600μm, 700μm, etc.

[0105] In addition, in the direction perpendicular to the back surface 102 of the substrate 100, if the distance between the surface of the first doped layer 110 on the side away from the substrate 100 and the front surface 101 of the substrate 100 is greater than the distance between the surface of the second doped layer 120 on the side away from the substrate 100 and the front surface 101 of the substrate 100, a part of the first doped layer 110 can also be removed by the second laser light treatment, that is , the initial first inclined sidewall 211 is also patterned.

[0106] Referring to FIG. 14, after performing the second laser light treatment, a second wet etching process may be performed to remove the first second doped layer 220 exposed from the second oxide layer 21. If the first second tunnel layer 260 was formed in the previous step, it is also necessary to etch the first second tunnel layer 260 by the second wet etching process, and the remaining first second tunnel layer 260 is used as the second tunnel layer 160. Specifically, a wet etching process may be performed using an NaOH solution to wet etch the first second doped layer 220, and the remaining first second doped layer 220 may be used as the second doped layer 120. After patterning the first second doped layer 220, the first second tunnel layer 260 may be etched with an acidic solution to form the second tunnel layer 160. In the second wet etching process, a second inclined sidewall 121 can be formed on the sidewall facing the separation region 103 of the second doped layer 120. Also, in the second wet etching process, a part of the first inclined sidewall 211 can be etched.

[0107] In some embodiments, the concentration of the NaOH solution for etching the first second doped layer may be 0.5% - 5%. For example, the concentration of the NaOH solution for etching the first second doped layer may be 0.5%, 1%, 2%, 3%, 4%, 5%, etc.

[0108] Continuing to refer to FIG. 14, in some embodiments, if the first second doped layer remains on the first doped layer, in the second wet etching step, the first second doped layer and the first second tunnel layer on the surface of the first doped layer can also be removed, and the remaining first second tunnel layer becomes the second tunnel layer 160.

[0109] In some embodiments, the process time of the second wet etching process may be from 300 s to 800 s, and the process temperature of the second wet etching may be from 60°C to 80°C. For example, the process time of the second wet etching process may be 300 s, 400 s, 500 s, 600 s, 700 s, 800 s, etc., and the process temperature of the second wet etching process may be 60°C, 70°C, 80°C, etc. In this way, the first second doped layer 220 and the first second tunnel layer 260 in other regions can be removed, the occurrence of excessive over-etching can be avoided, and the reduction of production efficiency can be avoided.

[0110] Referring to FIG. 15, in some embodiments, before forming the first electrode 130 and the second electrode 140, it may further include removing the first oxide layer 11 and the second oxide layer 21.

[0111] FIG. 16 is an electron micrograph of a local region after forming the first doped layer and the second doped layer in the method for manufacturing a solar cell provided by an embodiment of the present disclosure, and FIG. 17 is an electron micrograph of another local region after forming the first doped layer and the second doped layer in the method for manufacturing a solar cell provided by an embodiment of the present disclosure.

[0112] Referring to FIG. 16, the protruding film layer on the right side of FIG. 16 is the first doped layer, the left side is the separation region, the surface of the separation region has a pile structure, and the side wall of the first doped layer facing the separation region is the first inclined side wall, and the first inclined side wall has a first sub-inclined side wall, a platform surface, and a second sub-inclined side wall connected in sequence. Referring to FIG. 17, the protruding film layer on the right side of FIG. 17 is the second doped layer, the left side is the separation region, the surface of the separation region has a pile structure, and the side wall of the second doped layer facing the separation region is the second inclined side wall, and the second inclined side wall is a continuous inclination.

[0113] Referring to FIG. 18, a first electrode 130 that is in electrical contact with the first doped layer 110 and a second electrode 140 that is in electrical contact with the doped layer 120 are formed.

[0114] In some embodiments, the first electrode 130 and the second electrode 140 may be sintered from a through-fire type paste. The method of forming the first electrode 130 and the second electrode 140 may include printing a metal paste by a screen printing process. The metal paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0115] In some embodiments, the metal paste contains a material of a highly corrosive component such as glass, whereby the corrosive component corrodes some of the film layers of the battery during sintering, and the metal paste penetrates into some regions of the battery.

[0116] Continuing to refer to FIG. 18, before forming the first electrode 130 and the second electrode 140, the first passivation layer 170 and the second passivation layer 180 may be formed. Here, the first passivation layer 170 covers the surface of the front surface 101 of the substrate 100, and the second passivation layer 180 may cover the back surface 102 of the substrate 100 and the surfaces of the first doped layer 110 and the second doped layer 120 located on the back surface 102 of the substrate 100. The electrodes of the solar cell penetrate through the second passivation layer 180 and are in electrical contact with the first doped layer 110 or the second doped layer 120.

[0117] Embodiments of the present disclosure provide a method for manufacturing a solar cell. First, a substrate having opposing front and back surfaces is provided. A first first-doped layer is formed on the back surface of the substrate. A first patterning process is performed on the first first-doped layer to form a plurality of first-doped layers arranged at intervals in a first direction, and the sidewalls of the first-doped layers become first inclined sidewalls. On the back surface of the substrate, a first second-doped layer having a different doping type from the first-doped layer is formed. A second patterning process is performed on the first second-doped layer to form a second-doped layer, and the first-doped layer and the second-doped layer are alternately arranged along the first direction on the back surface of the substrate. The first-doped layer and the adjacent second-doped layer are separated by a separation region, and a part of the back surface is exposed by the separation region. The first inclined sidewall after the second patterning process becomes a first inclined sidewall, and the sidewall facing the separation region of the second-doped layer is a second inclined sidewall. A first electrode in electrical contact with the first-doped layer and a second electrode in electrical contact with the second-doped layer are formed. Thus, in the formed solar cell, the first inclined sidewall and the second inclined sidewall can improve the reflection of incident light, improve the utilization rate of light by the solar cell, and improve the efficiency of the cell.

[0118] Accordingly, other embodiments of the present disclosure also provide a photovoltaic module. Hereinafter, the photovoltaic module provided by other embodiments of the present disclosure will be described in detail with reference to the drawings. For the same or corresponding parts as those in the foregoing embodiments, the corresponding descriptions of the foregoing embodiments may be referred to, and the following will not be repeatedly described in detail.

[0119] FIG. 19 is a schematic structural diagram of a photovoltaic module provided by an embodiment of the present disclosure.

[0120] Referring to FIG. 19, the photovoltaic module includes a battery string in which a plurality of solar cells 300 formed by the solar cell described in the above-described embodiment or the manufacturing method of the solar cell described in the above-described embodiment are electrically connected, a sealing adhesive film 310 for covering the surface of the battery string, and a cover 320 for covering the surface of the sealing adhesive film 310 away from the battery string. The solar cells 300 are electrically connected in a monolithic or multi-slice form so as to form a plurality of battery strings, and the plurality of battery strings are electrically connected in series and / or in parallel.

[0121] Specifically, in some embodiments, the plurality of battery sheets may be electrically connected by conductive strips 33 0. FIG. 19 shows only one of the positional relationships between the solar cells, that is, the arrangement directions of the electrodes having the same polarity of the battery sheets are the same. In other words, the electrodes having the positive polarity of each battery sheet are all arranged facing the same side, so that each conductive strip 330 connects different sides of two adjacent battery sheets. In some embodiments, the battery sheets may be arranged such that the electrodes of different polarities face the same side, that is, the electrodes of a plurality of adjacent battery sheets may be arranged in the order of the first polarity, the second polarity, and the first polarity, respectively, so that the conductive strip connects two adjacent battery sheets on the same side.

[0122] In some embodiments, no gap is provided between the battery sheets, that is, the battery sheets may overlap each other.

[0123] In some embodiments, the encapsulant adhesive film 310 may include a first encapsulation layer covering one of the front or back surfaces of the battery string and a second encapsulation layer covering the other of the front or back surfaces of the battery string. Specifically, at least one of the first encapsulation layer or the second encapsulation layer may be an organic encapsulant adhesive film such as a polyvinyl butyral (PVB) adhesive film, an ethylene-vinyl acetate copolymer (EVA) adhesive film, an ethylene-octene copolymer elastomer (POE) adhesive film, or a polyethylene terephthalate (PET) adhesive film.

[0124] The first encapsulation layer and the second encapsulation layer have a boundary line before lamination. When the lamination process is performed to form the photovoltaic module, the concept of the first encapsulation layer and the second encapsulation layer no longer exists. That is, it should be understood that the first encapsulation layer and the second encapsulation layer are formed into an integral encapsulation layer 310.

[0125] In some embodiments, the cover 320 may be a cover having a light transmission function such as a glass cover or a plastic cover. Specifically, the surface of the cover 320 facing the encapsulant adhesive film 310 may be an uneven surface in order to increase the utilization rate of incident light. The cover 320 includes a first cover facing the first encapsulation layer and a second cover facing the second encapsulation layer.

[0126] Each of the above embodiments is for realizing specific examples of the present disclosure. Those skilled in the art will understand that in actual applications, various changes can be made in form and details without departing from the spirit and scope of the present disclosure. For any person skilled in the art, changes and modifications can be made respectively without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be defined by the scope of the claims.

Claims

1. A solar cell comprising: a substrate having opposing front and back surfaces; a first doped layer and a second doped layer arranged alternately along a first direction on the back surface, the first doped layer and the adjacent second doped layer being separated by a separation region, the doping type of the first doped layer and the doping type of the second doped layer being different, a part of the back surface being exposed by the separation region, a sidewall of the first doped layer toward the separation region being a first inclined sidewall, and a sidewall of the second doped layer toward the separation region being a second inclined sidewall; a first electrode in electrical contact with the first doped layer, and a second electrode in electrical contact with the second doped layer. A solar cell characterized by:

2. The angle between the first sloping sidewall and the surface of the first doped layer toward the back surface is a first acute angle, and the angle between the second sloping sidewall and the surface of the second doped layer toward the back surface is a second acute angle. The solar cell according to claim 1 .

3. The first angle is less than or equal to the second angle. The solar cell according to claim 2 .

4. the first angle is in the range of 25° to 60°; The second angle is in the range of 30° to 65°. The solar cell according to claim 2 .

5. The back surface exposed by the separation region has a pile structure, the pile structure including a plurality of pyramid structures. The solar cell according to claim 1 .

6. The width of the base of one of the pyramid structures is 2 μm to 4 μm in a direction parallel to the back surface. The solar cell according to claim 5 .

7. The first inclined sidewall includes a first sub-inclined sidewall, a platform surface, and a second sub-inclined sidewall, which are connected in sequence in a direction away from the rear surface of the substrate. The solar cell according to claim 1 .

8. In a direction perpendicular to a back surface of the substrate, a distance between a surface of the first doped layer facing away from the substrate and a front surface of the substrate is greater than a distance between a surface of the second doped layer facing away from the substrate and a front surface of the substrate, and the platform surface is closer to the back surface than the surface of the second doped layer facing away from the substrate. The solar cell according to claim 7 .

9. In a direction perpendicular to the rear surface of the substrate, the thickness of the second sub-inclined sidewall is smaller than the thickness of the first sub-inclined sidewall. The solar cell according to claim 7 .

10. A slope of the second sub-inclined sidewall relative to the rear surface is greater than a slope of the first sub-inclined sidewall. The solar cell according to claim 7 .

11. In a direction perpendicular to the rear surface of the substrate, the distance between the surface of the first doped layer away from the substrate and the front surface of the substrate is equal to or less than the distance between the surface of the second doped layer away from the substrate and the front surface of the substrate. The solar cell according to claim 1 .

12. The first sloped sidewall is a continuous slope. The solar cell according to claim 11 .

13. The second sloped sidewall is a continuous slope. The solar cell according to claim 1 .

14. The dopant ions in the first doped layer include boron ions, and the dopant ions in the second doped layer include phosphorus ions. The solar cell according to claim 1 .

15. A method for manufacturing a solar cell, comprising the steps of: Providing a substrate having opposing front and back surfaces; forming an initial first doped layer on a backside of the substrate; performing a first patterning process on the initial first doped layer to form a plurality of first doped layers spaced apart in a first direction, the sidewalls of the first doped layers being initial first sloping sidewalls; forming an initial second doped layer on a back surface of the substrate, the second doped layer having a doping type different from that of the first doped layer; performing a second patterning process on the initial second doped layer to form a second doped layer, the first doped layers and the second doped layers being alternately arranged along a first direction on the back surface of the substrate, the first doped layers and the adjacent second doped layers being separated by separation regions, and the separation regions exposing a part of the back surface, wherein the initial first sloping sidewall after the second patterning process becomes a first sloping sidewall, the first sloping sidewall being a sidewall of the first doped layer toward the separation region, and the second doped layer being a sidewall toward the separation region being a second sloping sidewall; forming a first electrode in electrical contact with the first doped layer and a second electrode in electrical contact with the second doped layer. A method for producing a solar cell comprising the steps of:

16. forming a first oxide layer on a surface of the first doped layer when forming the first doped layer; The process steps of the first patterning process include: patterning the initial first oxide layer with a first laser light treatment to form a first oxide layer on a surface of the first doped layer facing away from the substrate; removing the initial first doped layer exposed from the first oxide layer by a first wet etching process; The method further includes removing the first oxide layer before forming the first electrode and the second electrode. The method for producing a solar cell according to claim 15 .

17. The laser power of the first laser light treatment is 20 W to 30 W, and the process time of the first wet etching process is 500 s to 1000 s. The method for producing a solar cell according to claim 16 .

18. In the step of forming the first second doped layer, the first second doped layer is also disposed on a surface of the first doped layer, and a first second oxide layer is also formed on the surface of the first second doped layer; The second patterning process includes: performing a second laser light treatment to pattern the first second oxide layer to form a second oxide layer exposing at least the first second doped layer corresponding to the isolation region; performing a second wet etching process to remove the first second doped layer exposed from the first oxide layer; The method further includes removing the second oxide layer before forming the first electrode and the second electrode. The method for producing a solar cell according to claim 15 .

19. In the second wet etching process, the film layer on the surface of the first doped layer is also removed, the process time of the second wet etching treatment is 300s to 800s, and the process temperature of the second wet etching is 60°C to 80°C. The method for producing a solar cell according to claim 18 .

20. 1. A photovoltaic module comprising: A battery string in which a plurality of solar cells according to claims 1 to 14 or solar cells formed by the method for manufacturing a solar cell according to claims 15 to 19 are electrically connected together; a sealing adhesive film for covering a surface of the battery string; a cover for covering a surface of the sealing adhesive film that faces away from the battery string. A photovoltaic module comprising:

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