Solar cell and its manufacturing method, photovoltaic module
The solar cell design with inclined sidewalls addresses the low light utilization issue in IBC cells by reflecting incident light within the cell, improving efficiency and current density.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- ZHEJIANG JINKO SOLAR CO LTD
- Filing Date
- 2024-12-05
- Publication Date
- 2026-06-10
AI Technical Summary
Current solar cells, particularly IBC cells, suffer from low light utilization rates due to significant light reflection at normal vertical sidewalls, which reduces their efficiency.
The solar cell design incorporates first and second doped layers with inclined sidewalls on the substrate's back surface, allowing incident light to be reflected and utilized within the cell, enhancing light reflection and optical path length.
The inclined sidewalls improve light utilization and efficiency by reflecting incident light back into the cell, increasing current density and overall performance.
Smart Images
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Abstract
Description
Technical Field
[0001] Embodiments of the present disclosure relate to the field of photovoltaic power generation, and in particular 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 new energy alternatives. A solar cell is a device that converts solar light energy into electrical energy. Solar cells utilize the photovoltaic principle to generate carriers, and the electrodes extract the carriers, 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 light utilization rate of 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 at least advantageous for improving the light utilization rate of the solar cell.
Means for Solving the Problems
[0006] According to some embodiments of the present disclosure, embodiments of the present disclosure provide 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, wherein 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 the doping type of the second doped layer are different, a portion 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; a first electrode electrically in contact with the first doped layer; and a second electrode electrically in contact with the second doped layer.
[0007] In some embodiments, the angle between the first inclined sidewall and the surface of the first doped layer toward the back surface is an acute first angle, and the angle between the second inclined sidewall and the surface of the second doped layer toward the back surface is an acute second 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 the range of 25° to 60°, and the second angle is in the 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 pyramidal structures.
[0011] In some embodiments, the width of the base of one of the pyramidal structures is Back side The thickness is 2 μm to 4 μm in the direction parallel to the plane.
[0012] In some embodiments, the first inclined sidewall includes a first sub-inclined sidewall, a platform surface, and a second sub-inclined sidewall, connected in order away from the back surface of the substrate.
[0013] In some embodiments, in a direction perpendicular to the back surface of the substrate, the distance between the surface of the first dope layer away from the substrate and the front surface of the substrate is greater than the distance between the surface of the second dope layer 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 dope layer away from the substrate.
[0014] In some embodiments, the thickness of the second sub-inclined sidewall is smaller than the thickness of the first sub-inclined sidewall in a direction perpendicular to the back surface of the substrate.
[0015] In some embodiments, the slope of the second sub-inclined side wall is greater than the slope of the first sub-inclined side wall with respect to the back surface.
[0016] In some embodiments, in a direction perpendicular to the back surface of the substrate, the distance between the surface of the first dope layer away from the substrate and the front surface of the substrate is less than or equal to the distance between the surface of the second dope layer away from the substrate and the front surface of the substrate.
[0017] In some embodiments, the first inclined side wall is a continuous incline.
[0018] In some embodiments, the second inclined side wall is a continuous incline.
[0019] In some embodiments, the dopant ions in the first doping layer include boron ions, and the dopant ions in the second doping layer include phosphorus ions.
[0020] According to some embodiments of the present disclosure, embodiments of the present disclosure include the steps of: providing a substrate having opposing front and back surfaces; forming a first dope layer on the back surface of the substrate; performing a first patterning process on the first dope layer to form a plurality of first dope layers spaced apart in a first direction, wherein the sidewalls of the first dope layers are first inclined sidewalls; forming a first second dope layer on the back surface of the substrate having a different dope type from the first dope layer; and performing a second patterning process on the first second dope layer to form a second dope layer, wherein the first dope layer and The present invention also provides a method for manufacturing a solar cell, comprising the steps of: arranging the first dope layer and the second dope layer alternately along a first direction on the back surface of the substrate, separating the first dope layer from the adjacent second dope layer by a separation region, exposing a portion of the back surface by the separation region, wherein the first inclined sidewall after the second patterning process becomes the first inclined sidewall, the first inclined sidewall is the sidewall of the first dope layer facing the separation region, and the sidewall of the second dope layer facing the separation region is the second inclined sidewall; and forming a first electrode that electrically contacts the first dope layer and a second electrode that electrically contacts the second dope layer.
[0021] In some embodiments, when forming the first dope layer, the first oxide layer is also formed on the surface of the first dope layer, and here the first patterning process The steps include patterning the first oxide layer by a first laser treatment to form a first oxide layer on the surface of the first dope layer away from the substrate, and removing the first dope layer exposed from the first oxide layer by a first wet etching process, further including 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, the embodiments of the present disclosure include a photovoltaic module including a plurality of electrically connected battery strings, a sealing adhesive film for covering the surface of the battery string, and a cover for covering the surface of the sealing adhesive film away from the battery string, where the battery string is a solar cell described in the above embodiments or a solar cell formed by the manufacturing method of the solar cell described in the above embodiments.
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 an embodiment 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 electrically contacting the first doped region, and a second electrode electrically contacting the second doped region. In a related IBC cell, the back surface of the substrate includes a first doped layer and a second doped layer alternately arranged along a 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 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 an embodiment 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, the side wall between the separation region adjacent to the second doped region is a second inclined side wall, and the first inclined side wall and the second inclined side wall can improve the reflection of incident light, thereby improving the utilization rate of light by the solar cell and can improve the efficiency of the cell.
Brief Description of the Drawings
[0028] One or more embodiments are illustrated by images in the corresponding drawings, and these illustrative descriptions do not constitute limitations to the embodiments unless otherwise noted, nor do the images in the drawings constitute scale limitations. To better illustrate the embodiments of this disclosure or the technical means in the prior art, the drawings used in the embodiments are briefly described. The accompanying drawings represent only a subset of the embodiments of this disclosure, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort. [Figure 1] This is a schematic diagram of a solar cell provided in one embodiment of the present disclosure. [Figure 2] This is a schematic top view of a solar cell provided in one embodiment of the present disclosure. [Figure 3] This is a schematic diagram of a solar cell provided in other embodiments of this disclosure. [Figure 4] This is a schematic diagram of a solar cell provided in other embodiments of this disclosure. [Figure 5] This is a schematic diagram of a solar cell provided in other embodiments of this disclosure. [Figure 6] This is a schematic diagram of a solar cell provided in other embodiments of this disclosure. [Figure 7] This is a schematic diagram of a solar cell provided in other embodiments of this disclosure. [Figure 8] This is a schematic diagram of a solar cell provided in other embodiments of this disclosure. [Figure 9] ~ [Figure 15] These are schematic diagrams corresponding to each step in the method for manufacturing a solar cell provided in the embodiments of this disclosure. [Figure 16] This is an electron microscope image of a local region corresponding to one step in a method for manufacturing a solar cell provided in the embodiments of this disclosure. [Figure 17] These are electron microscope images of other local regions corresponding to one step in the method for manufacturing a solar cell provided in the embodiments of this disclosure. [Figure 18]This is a schematic diagram corresponding to one step in a method for manufacturing a solar cell provided in the embodiments of this disclosure. [Figure 19] This is a schematic diagram of a photovoltaic module provided in one embodiment of the present disclosure. [Modes for carrying out the invention]
[0029] From the background technology, it is clear that current solar cells have a problem in that there is room to improve their light utilization rate.
[0030] Embodiments of this disclosure provide a solar cell comprising a substrate and a first doped layer and a second doped layer arranged alternately along a 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 unlike the doping type of the first doped layer and the doping type of the second doped layer, a portion 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 first inclined side walls and the second inclined side walls can improve the reflection of incident light, thereby improving the utilization rate of light by the solar cell and improving the efficiency of the cell.
[0031] To further clarify the object, technical means, and advantages of the embodiments of the present invention, each embodiment of this disclosure will be described in detail below with reference to the drawings. However, while many technical details are presented in each embodiment of this disclosure to help the reader better understand the disclosure, those skilled in the art will understand that the technical means claimed by this disclosure can be achieved without these technical details or the various changes and modifications based on the embodiments below.
[0032] Figure 1 is a schematic diagram of the structure of a solar cell provided in one embodiment of the present disclosure. Figure 2 is a schematic top view of the solar cell shown in Figure 1.
[0033] Referring to Figures 1 and 2, the solar cell comprises a substrate 100 having opposing front surfaces 101 and back surfaces 102, and a first doped layer 110 and a second doped layer 120 arranged alternately along a first direction X on the back surface 102, wherein the first doped layer 110 and the adjacent second doped layer 120 are separated by a separation region 103, and the doping type of the first doped layer 110 and the doping type of the second doped layer 120 are different, and the separation region The first doped layer 110 and the second doped layer 120 include a first doped layer 110 and a second doped layer 120, the first doped layer 110 and the second doped layer 120, the first electrode 130 and the second electrode 140, which are in electrical contact with the first doped layer 110 and the second electrode 140, respectively. The first electrode 130 is in electrical contact with the first doped layer 110 and the second doped layer 120 is in electrical contact with the second doped layer 120.
[0034] In related technologies, the back surface of an IBC battery substrate is provided with a first doped layer and a second doped layer arranged alternately along a first direction and having different doping types, with the first doped layer and the adjacent second doped layer separated by a separation region. However, the sidewalls of the first doped layer facing the separation region are normal vertical sidewalls, and the sidewalls of the second doped layer facing the separation region are also normal vertical sidewalls, resulting in a large amount of light incident on the solar cell being reflected. When incident light is irradiated by normal vertical sidewalls, it is reflected outside the battery instead of inside, becoming unusable. This reduces the light utilization rate of the solar cell and affects the battery's efficiency.
[0035] In the embodiments of this disclosure, the side wall of the first dope layer 110 facing the separation region 103 is designated as the first inclined side wall 111, and the side wall of the second dope layer 120 facing the separation region 103 is designated as the second inclined side wall 121. When incident light is irradiated onto the first inclined side wall 111 or the second inclined side wall 121, it is reflected within 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, thereby increasing the utilization rate of light in the solar cell and improving the efficiency of the battery. Furthermore, the first inclined side wall 111 and the second inclined side wall 121 can lengthen the optical path length within the battery, thereby improving the current density of the solar cell.
[0036] The battery may have multiple first doping layers 110, second doping layers 120, and isolation regions 103. In the drawing, only one first doping layer 110, one second doping layer 120, and one isolation region 103 are shown.
[0037] In some embodiments, the solar cell may be an IBC (Interdigitated Back Contact) battery.
[0038] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material consists of a single element, such as silicon or germanium. 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), and for example, silicon may be at least one of single-crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.
[0039] In some embodiments, the substrate 100 may be made of 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 selenium. The substrate 100 may be a sapphire substrate, a silicon substrate on an insulator, or a germanium substrate on an insulator.
[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 the 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 the Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).
[0041] In some embodiments, the dopant ions in the first doping layer 110 may include a P-type dopant element, such as boron ions, and the dopant ions in the second doping layer 120 may include an N-type dopant element, such as phosphorus ions. When the substrate 100 is an N-type substrate, the doping type of the first doping layer 110 is different from the doping type of the substrate 100, and the doping type of the second doping layer 120 is the same as the doping type of the substrate 100. In this case, a pn junction is formed between the first doping layer 110 and the substrate 100, and the first doping layer 110 can function as an emitter of a solar cell. If the substrate 100 is a P-type substrate, the doping type of the first doping layer 110 is the same as the doping type of the substrate 100, while the doping type of the second doping layer 120 is different from that of the substrate 100. In this case, a pn junction is formed between the second doping layer 120 and the substrate 100, and the second doping layer 120 can function as the emitter of the solar cell. Since both the first doping layer 110 and the second doping layer 120, which have different doping types, are located on the back surface 102 of the substrate 100, the area occupied by the electrodes relative to the front surface 101 of the substrate 100 can be reduced, eliminating obstruction by the gate line on the surface of the battery. This eliminates the light-shielding current loss of the metal electrodes and maximizes the utilization of incident photons. Furthermore, since there is no need to consider the problem of obstruction by the gate line, the proportion of the gate line can be appropriately increased, thereby reducing the series resistance and resulting in a high curve factor.
[0042] Referring to Figure 3, in some embodiments, the angle between the first inclined sidewall 111 and the surface of the first doped layer 110 facing the back surface 102 may be an acute first angle a. The angle between the second inclined sidewall 121 and the surface of the second doped layer 120 facing the back surface 102 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 toward the separation region 103 relative to the first doped layer 110, and the second inclined sidewall 121 protrudes toward the separation region 103 relative 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, thereby improving the light utilization rate of the solar cell and improving the efficiency of the battery.
[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. Since the gradient of the first inclined sidewall 111 is smaller than that of the second inclined sidewall 121, the first inclined sidewall 111 and the second inclined sidewall 121 reflect different incident light, allowing incident light at different angles to be reflected back into the cell and reused, further improving the light utilization rate of the solar cell.
[0044] In the solar cell manufacturing process, the etching time for the first inclined sidewall 111 corresponding to the first dope layer 110 is longer than the etching time for the second inclined sidewall 121 corresponding to the second dope layer 120. This allows the gradient of the first inclined sidewall 111 to be smaller than the gradient of the second inclined sidewall 121, thereby making the first angle a 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 is acceptable. If the magnitude of the first angle a is too large or too small, the gradient strength of the first inclined side wall 111 will decrease, the first inclined side wall 111 will tend to become perpendicular to the side wall, the reflection effect of the first inclined side wall 111 with respect to incident light will be 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 side wall 121 will decrease, the second inclined side wall 121 will tend to become perpendicular to the side wall, the reflection effect of the second inclined side wall 121 with respect to incident light will be 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, and when the first angle a is 25° to 60° and the second angle b is 30° to 65°, the light utilization rate of the battery can be effectively improved and the efficiency of the battery can be improved.
[0046] Referring to Figure 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 connected in order away from the back surface 102 of the substrate 100. The platform surface 1112 may be parallel to the back surface of the substrate 100 or may have a constant slope. In this way, the first sub-inclined sidewall 1111, the second sub-inclined sidewall 1113, and the platform surface 1112, each located in a different plane, can increase the reflection of incident light to the battery, further improving the light utilization rate of the solar cell and thus further improving the battery efficiency. In addition, the first sub-inclined sidewall 1111, the platform surface 1112, and the second sub-inclined sidewall 1113 can further scatter the light incident on the battery, thereby further increasing the optical path length within the battery and further increasing the current density of the solar cell.
[0047] In some embodiments, the distance between the surface of the first dope layer 110 away from the substrate 100 and the front surface 101 of the substrate 100, in a direction perpendicular to the back surface 102 of the substrate 100, may be greater than the distance between the surface of the second dope layer 120 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 dope layer 120 away from the substrate 100. In the manufacturing of solar cells, if the distance between the surface of the first dope layer 110 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 dope layer 120 away from the substrate 100 and the front surface 101 of the substrate 100, the unpatterned second dope layer 120 can cover a portion of the first inclined sidewall 111. As a result, when patterning the isolation region 103 to expose the back surface 102 of the substrate 100, the etching time for the portion of the first inclined sidewall 111 exposed from the second dope layer 120 will be longer than the portion of the first inclined sidewall 111 covered by the second dope layer 120. This allows the first inclined sidewall 111 to be formed after patterning is complete, including the first sub-inclined sidewall 1111, the platform surface 1112, and the second sub-inclined sidewall 1113. Each of the first sub-inclined sidewall 1111, the second sub-inclined sidewall 1113, and the platform surface 1112, which are in different planes, can increase the reflection of incident light to the battery, thereby further improving the light utilization rate of the solar cell and further improving battery efficiency.
[0048] Furthermore, when fabricating the solar cell, if the second doping layer 120 of the isolation region 103 is patterned to expose the back surface 102 of the substrate 100, the platform surface 1112, which is originally flush with the surface of the second doping layer 120 that is away from the substrate 100, will also be etched. Consequently, the platform surface 1112 is closer to the back surface 102 than to the surface of the second doping layer 120 that is 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 front surface of the second dope layer 120 away from the substrate 100 and the back surface 102.
[0050] Continuing with Figure 4, in some embodiments, perpendicular to the back surface 102 of the substrate 100 In this direction, the thickness of the second sub-inclined sidewall 1113 may be less 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, the etching direction of the etching process is towards the substrate 100. Therefore, the etching time for the first sub-inclined sidewall 1111, which is closer to the substrate 100, is shorter than that for the second sub-inclined sidewall 1113, which is further away from the substrate 100. Consequently, the etched thickness of the first sub-inclined sidewall 1111 is smaller than the etched thickness of the second sub-inclined sidewall 1113, and the final thickness of the 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 side wall 1111 and the second sub-inclined side wall 1113 are not on the same plane, and the first sub-inclined side wall 1111 and the second sub-inclined side wall 1113 can reflect incident light at different angles, thereby increasing the utilization rate of incident light, further improving the light utilization rate of the battery and improving the efficiency of the battery.
[0051] In other embodiments, the thickness of the second sub-inclined sidewall 1113 in a direction perpendicular to the back surface 102 of the substrate 100 may be greater than or equal to the thickness of the first sub-inclined sidewall 1111.
[0052] Referring to Figure 5, in some embodiments, the gradient of the second sub-inclined sidewall 1113 relative to the back surface 102 may be greater than the gradient of the first sub-inclined sidewall 1111. That is, the second sub-inclined sidewall 1113 is closer to 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 from the side away from the substrate 100 toward the substrate 100. Therefore, the etching time for the second sub-inclined sidewall 1113, which is closer to the outside, is longer than that for the first sub-inclined sidewall 1111, which is closer to the substrate 100. Consequently, the gradient of the second sub-inclined sidewall 1113 relative to the back surface 102 may be greater than the gradient of the first sub-inclined sidewall 1111. Thus, since the first sub-inclined side wall 1111 and the second sub-inclined side wall 1113 have different inclines, they can reflect incident light at different angles, thereby increasing the utilization rate of incident light and further improving the light utilization rate of the battery, thereby improving the battery's efficiency.
[0053] In other embodiments, the slope of the second sub-inclined side wall 1113 and the slope of the first sub-inclined side wall 1111 may be the same with respect to the back surface 102.
[0054] Referring to Figure 6, in some embodiments, the distance between the surface of the first dope layer 110 away from the substrate 100 and the front surface 101 of the substrate 100 in a direction perpendicular to the back surface 102 of the substrate 100 may be less than or equal to the distance between the surface of the second dope layer 120 away from the substrate 100 and the front surface 101 of the substrate 100. That is, the surface of the second dope layer 120 away from the substrate 100 protrudes away from the substrate 100 relative to the surface of the first dope layer 110 away from the substrate 100, or the surface of the second dope layer 120 away from the substrate 100 is flush with the surface of the first dope layer 110 away from the substrate 100.
[0055] It should be noted that the distance between the surface of the first dope layer 110 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 dope layer 120 away from the substrate 100 and the front surface 101 of the substrate 100 is not equivalent to the thickness of the first dope layer 110 being less than or equal to the thickness of the second dope layer 120. Since some degree of over-etching may have occurred when forming the first dope layer 110 and the second dope layer 120, a portion of the back surface 102 of the substrate 100 corresponding to the first dope layer 110 and a portion of the back surface 102 of the substrate 100 corresponding to the second dope layer 120 are not necessarily on the same plane. Therefore, the relationship between the surface of the first dope layer 110 away from the substrate 100 and the surface of the second dope layer 120 away from the substrate 100 cannot be explained by the relationship of thickness. Also, referring to Figures 4 to 6, the first doping layer 110 and the second doping layer 120 are formed If this occurs and over-etching occurs on the substrate 100, a portion of the sidewall of the substrate 100 adjacent to the inclined sidewall of the first dope layer 110 may be inclined.
[0056] Continuing with reference to Figure 6, in some embodiments, the first inclined sidewall 111 may have a continuous inclination. In the process of forming the first dope layer 110 and the second dope layer 120, the distance between the surface of the second dope layer 120 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 dope layer 110 away from the substrate 100 and the front surface 101 of the substrate 100, so that the second dope layer 120 before patterning can cover the entire first inclined sidewall 111, and therefore the first inclined sidewall 111 undergoes only one etching process when patterning the second dope layer 120, so that the first inclined sidewall 111 does not have a discontinuous inclination, and the first inclined sidewall 111 that is finally formed may still have a continuous inclination. After forming the first dope layer 110 and the second dope layer 120, a second passivation layer 180 can be formed on the back surface 102 of the substrate 100, covering the first dope layer 110 and the second dope layer 120. Therefore, making the first inclined side wall 111 a continuous inclination is also advantageous for forming the second passivation layer 180, facilitating the deposition of the second passivation layer 180, reducing the difficulty of deposition, lowering the difficulty of production, and improving production efficiency.
[0057] In some embodiments, the second inclined sidewall 121 may have a continuous incline. The second inclined sidewall 121 is an inclined sidewall left over when patterning the second dope layer 120, and since the second inclined sidewall 121 has undergone only one continuous etching process, the second inclined sidewall 121 can have a continuous incline.
[0058] Refer to Figure 7, in some embodiments, the separated region 103 is exposed Back side102 may have a pile structure 104, and the pile structure 104 may include multiple pyramidal structures. The second dope layer 120 can be patterned so that the back surface 102 of the substrate 100 in the isolation region 103 is exposed, and at the same time, the back surface 102 exposed in the isolation region 103 can be pile-processed using an etching atmosphere so that the back surface 102 exposed in the isolation region 103 has a pile structure. In this way, the pile structure can reflect incident light so that a portion of the incident light can be reflected back into the battery for reuse, further increasing the light utilization rate of the battery and improving the efficiency of the battery. In addition, the pile structure of the back surface 102 exposed in the isolation region 103 can further scatter the light incident on the battery, thereby further increasing the optical path length in the battery and further increasing the current density of the solar cell.
[0059] In some embodiments, the width of the base of one pyramidal structure is Back side The width may be 2 μm to 4 μm in the direction parallel to 102. For example, the width of the base of one pyramidal structure is Back side The width may be 2 μm, 3 μm, 4 μm, etc., in the direction parallel to 102. The width of the base of the pyramid structure is the maximum width of the base of the pyramid structure in any direction parallel to the back surface 102. Back side If the width of the base of the pyramidal structure is too large in the direction parallel to 102, the number of pyramidal structures in the separation region 103 will be too small, the effect of improving reflection of incident light by the pile structure will be poor, the light utilization rate of the battery will remain low, and there will still be room for improvement in the battery's efficiency. If the width of the base of the pyramidal structure is too small, the height of the pyramidal structure will also be small accordingly, the effect of improving reflection of incident light by the pile structure will remain poor, the light utilization rate of the battery will remain low, and there will still be room for improvement in the battery's efficiency. Therefore, it is necessary to select an appropriate range for the width of the base of the pyramidal structure in the direction parallel to the back surface 102. If the width of the base of one pyramidal structure is 2 μm to 4 μm, the effect of improving reflection of incident light by the pile structure will be good, the light utilization efficiency of the battery can be effectively improved, and the battery's efficiency can be effectively improved.
[0060] In the pile structure shown in Figure 7, the dimensions of each pyramidal structure are the same. However, in an actual pile structure, the dimensions of each pyramidal structure may differ. Specifically, the width of each pyramidal structure in the direction parallel to the back surface 102 and the height of each pyramidal structure may differ.
[0061] Referring to Figure 8, in some embodiments, the substrate 100 may be piled so that a pile is formed on the front surface of the substrate 100, thereby improving the light absorption utilization rate of the substrate 100. In some embodiments, the pile may be a pyramidal pile, which, as a general pile, not only reduces the reflectivity of the surface of the substrate 100 but also forms a light trap, enhancing the light absorption effect of the substrate 100 and increasing 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 located between the first doped layer 110 and the substrate 100, and the second tunnel layer 160 is located between the second doped layer 120 and the substrate 100. The first tunnel layer 150 and the second tunnel layer 160 prevent minority carriers from passing through while allowing majority carriers to tunnel into the doped layer. This allows majority carriers to be transported laterally within the doped layer and collected by the electrodes, reducing carrier recombination and increasing the open-circuit voltage and short-circuit current of the cell. In this case, the tunnel oxide layer and the doped layer constitute a tunnel oxide passivation contact structure, enabling excellent interfacial passivation and selective carrier collection, thereby improving the photoelectric conversion efficiency of the back-contact cell.
[0063] Furthermore, when forming the first dope layer 110 and the second dope layer 120 to cause over-etching on the substrate 100, the side wall of the first tunnel layer 150 adjacent to the inclined side wall of the first dope 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 dope layer 120 may be inclined.
[0064] In some embodiments, the material of the first tunnel layer 150 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride. The material of the second tunnel layer 160 may 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 may cover 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, as well as the surfaces of the first doping layer 110 and the second doping layer 120 located on the back surface 102 of the substrate 100. The electrodes of the solar cell penetrate the second passivation layer 180 and make electrical contact with the first doping layer 110 or the second doping layer 120.
[0066] The first passivation layer 170 exhibits a good passivation effect on the front surface 101 of the substrate 100, reducing the defect level density on the front surface 101 of the substrate 100 and effectively suppressing carrier recombination on the front surface 101 of the substrate 100. Furthermore, the first passivation layer 170 exhibits a good anti-reflective effect, reducing reflection of incident light by the front surface 101 of the substrate 100 and improving the utilization rate of incident light by the substrate 100. The second passivation layer 180 exhibits a good passivation effect on the back surface 102 of the substrate 100, for example, providing good chemical passivation to the dangling bonds on the back surface 102 of the substrate 100. This method saturates the bond, reduces the defect level density on the back surface 102 of the substrate 100, and suppresses carrier recombination on the back surface of the substrate 100.
[0067] In some embodiments, the material of the first passivation layer 170 may include one of silicon nitride, aluminum oxide, silicon nitride, or silicon oxynitride. The material of the second passivation layer 180 may include at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.
[0068] In some embodiments, the first passivation layer 170 may be a single-layer structure or a multilayer structure. In the case of a multilayer structure, the materials of the different layers may be different from each other, or the materials of some layers may be the same and not the same as the materials of other layers. For example, the first passivation layer 170 may be a multilayer structure of silicon nitride layers and aluminum oxide layers. In some embodiments, the second passivation layer 180 may be a single-layer structure. In some embodiments, the second passivation layer 180 may be a multilayer structure, where the materials of each layer of the multilayer structure may be different from each other, or the materials of some layers may be different and the materials of other parts may be the same. For example, the second passivation layer 180 may be a multilayer structure of silicon nitride layers and aluminum oxide layers.
[0069] If the second passivation layer 180 includes an aluminum oxide layer, a groove formation process using laser light may be performed first, followed by a screen printing process, 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 paste. The method for 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 contain at least one of silver, aluminum, copper, tin, gold, lead, or nickel.
[0071] In some embodiments, the width of the first doping layer 110 in the first direction X may be greater than the width of the second doping layer 120 in the first direction X, and accordingly, the width of the first electrode 130 electrically in contact with the first doping layer 110 in the first direction X may be greater than the width of the second electrode 140 electrically in contact with the second doping layer 120 in the first direction X. Thus, the first electrode 130 having a larger width in the first direction X can collect carriers more effectively and improve the current transmission effect of the solar cell.
[0072] In some embodiments, the metal paste contains highly corrosive components such as glass, which causes the corrosive components to corrode a portion of the film layer of the battery during sintering, allowing the metal paste to penetrate into a portion of the battery. Embodiments of this disclosure provide a solar cell comprising a substrate and a first doped layer and a second doped layer arranged alternately along a 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 unlike the doping type of the first doped layer and the doping type of the second doped layer, a portion of the back surface is exposed by the separation region, the sidewall of the first doped layer facing the separation region becomes a first inclined sidewall, and the sidewall of the second doped layer facing the separation region becomes a second inclined sidewall. 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 and second inclined sidewalls can improve the reflection of incident light, thereby improving the utilization rate of light by the solar cell and improving the efficiency of the battery.
[0073] Correspondingly, other embodiments of this disclosure also provide methods for manufacturing solar cells that can be used to manufacture the solar cells described in the embodiments described above. The solar cells provided in other embodiments of this disclosure will be described in detail below with reference to the drawings, but are identical to those in the embodiments described above. For the corresponding parts, please refer to the corresponding explanations in the previously mentioned embodiments, and we will not repeat them in detail below.
[0074] Referring to Figure 9, a substrate 100 having opposing 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 consists of a single element, such as silicon or germanium. 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), and for example, silicon may be at least one of single-crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.
[0076] In some embodiments, the substrate 100 may be made of 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 selenium. The substrate 100 may be a sapphire substrate, a silicon substrate on an insulator, or a germanium substrate on an insulator.
[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 the 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 the Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).
[0078] Referring to Figure 10, the 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 to form the first doped layer 210 by diffusion doping. The diffusion doping process temperature may be 800°C to 1200°C, and the diffusion doping process time may be 2 hours to 5 hours. For example, the diffusion doping process temperature may be 800°C, 1000°C, 1100°C, 1200°C, etc., and the diffusion doping process time may be 2 hours, 3 hours, 4 hours, 5 hours, etc.
[0080] In some embodiments, the first doped layer 210 may be doped with boron ions.
[0081] In some embodiments, before forming the first dope layer 210, a first tunnel layer 250 may be formed on the back surface 102 of the substrate 100, covering the back surface 102 of the substrate 100, and the first dope layer 210 covers the surface of the first tunnel layer 250 that is away from the substrate 100.
[0082] In some embodiments, when forming the first doped layer 210, the first oxide layer 10 may be formed on the surface of the first doped layer 210. The first oxide layer 10 may be borosilicate glass (BSG). The thickness of the first oxide layer 10 may be 100 nm to 200 nm. For example, the thickness of the first oxide layer 10 may be 100 nm, 150 nm, 200 nm, etc.
[0083] Referring to Figure 11, the first doping layer 210 is subjected to the first patterning process. This forms a plurality of first doped layers 110 arranged at intervals in the first direction X. The side walls of the first doped layers 110 become the first inclined side walls 211.
[0084] 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 portion of the substrate 100 may be removed during the first patterning process, thereby making the thickness of the portion of the substrate 100 covered by the first dope layer 110 slightly greater than the thickness of the portion of the substrate 100 not covered by the first dope layer 110.
[0086] In some embodiments, the first patterning process may include a step of patterning the initial first oxide layer 10 by a first laser treatment to form a first oxide layer 11 on the surface of the first dope layer 110 away from the substrate 100. The first laser treatment does not create a slope on the sidewalls of the first oxide layer 11, so the sidewalls of the first oxide layer 11 are vertical.
[0087] Furthermore, patterning the first doped layer 210 using a laser light processing process would alter the first doped layer 110, affecting the normal performance of the battery. Therefore, the laser light processing process should only pattern the first oxide layer 10 and not the first doped layer 210.
[0088] In some embodiments, the laser power of the first laser treatment may be 20W to 30W. For example, the power of the first laser treatment may be 20W, 25W, or 30W. If the power of the first laser treatment is too high, it will not only lead to energy waste and increase production costs, but may also denature the first dope layer 110 and affect the performance of the battery. If the power of the first laser treatment is too low, the efficiency of patterning the first oxide layer 10 will be too low. For this reason, it is necessary to select an appropriate range for the power of the first laser treatment, and if the laser power of the first laser treatment is set to 20W to 30W, it is possible to improve production efficiency while avoiding denature of the first dope layer without increasing production costs.
[0089] In some embodiments, the width of the first laser light processing region in the first direction X may be 300 μm to 600 μm. For example, the width of the first laser light processing region in the first direction X may be 300 μm, 400 μm, 500 μm, 600 μm, etc. The depth of the first laser light processing region may be 3 μm to 6 μm. For example, the depth of the first laser light processing region may be 3 μm, 4 μm, 5 μm, 6 μm, etc.
[0090] In some embodiments, following the first laser phototreatment, a first wet etching process can remove the first doped layer 210 exposed from the first oxide layer 11, and the first wet etching process can also remove surface damage caused by the laser phototreatment process. If the first tunnel layer 250 is formed in the preceding step, the first wet etching process may also be used to etch the first tunnel layer 250, and the remaining first tunnel layer 250 will become the first tunnel layer 150. Specifically, the first doped layer 210 may be wet-etched using a NaOH solution, and the remaining first doped layer 210 may become the first doped layer 110. After patterning the first doped layer 210, the first tunnel layer 250 may be etched with an acidic solution to form the first tunnel layer 150. In the mixing process, the first inclined sidewall 211 can be formed on the sidewall of the first doped layer 110 toward the separation region 103.
[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 for the first wet etching process may be 500s to 1000s. For example, the process time for the first wet etching process may be 500s, 600s, 700s, 800s, 900s, 1000s, etc. If the process time for the first wet etching process is too long, it may cause excessive over-etching of the substrate 100, potentially affecting the structure of the battery. If the process time for the first wet etching process is too short, the first dope layer 210 and the first tunnel layer 250 in other areas may not be completely removed, potentially affecting 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 for the first wet etching process is set to 500s to 1000s, the first dope layer 210 and the first tunnel layer 250 in other areas can be removed while avoiding excessive over-etching of the substrate 100.
[0093] Furthermore, when patterning the first oxide layer 10 using the laser light processing process, it is not necessary to form a patterning mask layer on the first oxide layer 10, thus simplifying the process flow and improving production efficiency. After patterning the first oxide layer 10 using laser light processing, the remaining first oxide layer 10 becomes the first oxide layer 11, and this first oxide layer 11 can be used as a patterning mask layer. In the first wet etching process, the first doped layer 210 is etched using the first oxide layer 11 as a mask, and the remaining first doped layer 210 becomes the first doped layer 110. In this process, the oxide layer formed during the doping process is first patterned using laser light processing, and the patterned oxide layer can be used directly as the mask layer for etching in the next step. This avoids the process steps of forming and removing the mask layer, simplifies the process flow, improves production efficiency, and reduces production costs.
[0094] Referring to Figure 12, a first second doping layer 220, which has a different doping type from the first doping layer 110, is formed on the back surface 102 of the substrate 100.
[0095] Specifically, the substrate 100 can be placed in a diffusion furnace to form the first second doped layer 220 by diffusion doping. The diffusion doping process temperature may be 700°C to 1000°C, and the diffusion doping process time may be 1 hour to 3 hours. For example, the diffusion doping process temperature may be 700°C, 800°C, 900°C, 1000°C, etc., and the diffusion doping process time may be 1 hour, 2 hours, 3 hours, etc.
[0096] In some embodiments, the first second doping layer 220 may be doped with phosphate ions.
[0097] In some embodiments, before forming the first second dope layer 220, a first second tunnel layer 260 may be formed on the back surface 102 of the substrate 100, covering at least a portion of the back surface 102 of the substrate 100, and the first second dope layer 220 covers the surface of the first second tunnel layer 260 that is away from the substrate 100.
[0098] In some embodiments, in the step of forming the first second dope layer 220, the first second dope layer 220 is also placed on the surface of the first dope layer 110, and the first second oxide layer 20 is also formed on the surface of the first second dope layer 220. The first second oxide layer 20 may be phosphosilica 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, or 200 nm.
[0099] Referring to Figures 13 to 14, the first second dope layer 220 is subjected to a second patterning process to form a second dope layer 120, and the first dope layer 110 and the second dope layer 120 are arranged alternately along the first direction X on the back surface 102 of the substrate 100, and the first dope layer 110 and the adjacent second dope layer 120 are separated by a separation region 103, 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 the sidewall of the first dope layer 110 facing the separation region 103, and the sidewall of the second dope layer 120 facing the separation region 103 is the second inclined sidewall 121.
[0100] In some embodiments, the second patterning process may include, with reference to Figure 13, performing a second laser treatment to pattern the first second oxide layer 20 to form a second oxide layer 21 that exposes the first second doped layer 220 corresponding to at least the isolation region 103. The second laser treatment does not create a slope on the sidewalls of the second oxide layer 21, but rather the sidewalls of the second oxide layer 21 are vertical.
[0101] Furthermore, patterning the first second dope layer 220 using a laser light processing process would alter the second dope layer 120, affecting the normal performance of the battery. Therefore, the laser light processing process should only pattern the first second oxide layer 20 and not the first second dope layer 220.
[0102] Furthermore, if the initial second oxide layer 20 formed in the previous step remains on the first dope layer 110, the initial second oxide layer 20 on the first dope layer 110 can also be removed by a second laser light treatment.
[0103] In some embodiments, the laser power of the second laser treatment may be 20W to 30W. For example, the power of the second laser treatment may be 20W, 25W, or 30W. If the power of the second laser treatment is too high, it will not only lead to energy waste and increase production costs, but may also denature the second dope layer 120 and affect the performance of the battery. If the power of the second laser treatment is too low, the efficiency of patterning the first second oxide layer 20 will be too low. For this reason, it is necessary to select an appropriate range for the power of the second laser treatment, and if the laser power of the second laser treatment is set to 20W to 30W, it is possible to improve production efficiency while avoiding denature of the second dope layer without increasing production costs.
[0104] In some embodiments, the width of the second laser light processing region in the first direction X may be 400 μm to 700 μm. For example, the width of the second laser light processing region in the first direction X may be 400 μm, 500 μm, 600 μm, 700 μm, etc.
[0105] Furthermore, if, in a direction perpendicular to the back surface 102 of the substrate 100, the distance between the surface of the first dope layer 110 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 dope layer 120 away from the substrate 100 and the front surface 101 of the substrate 100, then a portion of the first dope layer 110 can also be removed by the second laser light treatment, i.e. The first inclined side wall 211 is also patterned.
[0106] Referring to Figure 14, after the second laser treatment, a second wet etching process may be performed to remove the first second dope layer 220 exposed from the second oxide layer 21. If the first second tunnel layer 260 was formed in the previous step, the second wet etching process may also be necessary to etch the first second tunnel layer 260, and the remaining first second tunnel layer 260 will become the second tunnel layer 160. Specifically, the first second dope layer 220 may be wet-etched using a NaOH solution, and the remaining first second dope layer 220 may become the second dope layer 120. After patterning the first second dope 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 of the second dope layer 120 facing the separation region 103, and a portion of the first inclined sidewall 211 can also be etched in the second wet etching process.
[0107] In some embodiments, the concentration of the NaOH solution for etching the first second dope layer may be 0.5% to 5%. For example, the concentration of the NaOH solution for etching the first second dope layer may be 0.5%, 1%, 2%, 3%, 4%, 5%, etc.
[0108] Continuing with reference to Figure 14, in some embodiments, if the initial second dope layer remains on the first dope layer, the initial second dope layer and the initial second tunnel layer on the surface of the first dope layer can also be removed in the second wet etching step, and the remaining initial second tunnel layer becomes the second tunnel layer 160.
[0109] In some embodiments, the process time for the second wet etching process may be 300s to 800s, and the process temperature for the second wet etching may be 60°C to 80°C. For example, the process time for the second wet etching process may be 300s, 400s, 500s, 600s, 700s, 800s, etc., and the process temperature for the second wet etching process may be 60°C, 70°C, 80°C, etc. In this way, the first second dope layer 220 and the first second tunnel layer 260 in other regions can be removed, and the occurrence of excessive over-etching can be avoided, thus preventing a decrease in production efficiency.
[0110] Referring to Figure 15, in some embodiments, the first oxide layer 11 and the second oxide layer 21 may be further removed before forming the first electrode 130 and the second electrode 140.
[0111] Figure 16 is an electron microscope image of a local region after the formation of the first dope layer and the second dope layer in the method for manufacturing a solar cell provided in the embodiments of this disclosure, and Figure 17 is an electron microscope image of another local region after the formation of the first dope layer and the second dope layer in the method for manufacturing a solar cell provided in the embodiments of this disclosure.
[0112] Referring to Figure 16, the protruding membrane layer on the right side of Figure 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, which has a sequentially connected first sub-inclined side wall, platform surface, and second sub-inclined side wall. Referring to Figure 17, the protruding membrane layer on the right side of Figure 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, which has a continuous incline.
[0113] Referring to Figure 18, the first electrode 130 and the second electrode are in electrical contact with the first doped layer 110. A second electrode 140 is formed that is in electrical contact with the doped layer 120.
[0114] In some embodiments, the first electrode 130 and the second electrode 140 may be sintered from a fire-through paste. The method for 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 contain at least one of silver, aluminum, copper, tin, gold, lead, or nickel.
[0115] In some embodiments, the metal paste contains highly corrosive materials such as glass, which causes the corrosive components to corrode a portion of the film layer of the battery during sintering, allowing the metal paste to penetrate into a portion of the battery.
[0116] Referring again to Figure 18, a first passivation layer 170 and a second passivation layer 180 may be formed before forming the first electrode 130 and the second electrode 140. Here, the first passivation layer 170 may cover the front surface 101 of the substrate 100, and the second passivation layer 180 may cover the back surface 102 of the substrate 100, as well as the surfaces of the first doping layer 110 and the second doping layer 120 located on the back surface 102 of the substrate 100. The electrodes of the solar cell penetrate the second passivation layer 180 and make electrical contact with the first doping layer 110 or the second doping layer 120.
[0117] Embodiments of this disclosure provide a method for manufacturing a solar cell. First, a substrate having opposing front and back surfaces is provided. A first doped layer is formed on the back surface of the substrate. A first patterning process is performed on the first doped layer to form a plurality of first doped layers spaced apart in a first direction, and the sidewalls of the first doped layers become the first inclined sidewalls. A first second doped layer with a different doping type from the first doped layer is formed on the back surface of the substrate. A second patterning process is performed on the first second doped layer to form a second doped layer, and the first doped layers and second doped layers are alternately arranged along a first direction on the back surface of the substrate, separated from the first doped layer and the adjacent second doped layer 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 the first inclined sidewall, and the sidewall of the second doped layer facing the separation region becomes the second inclined sidewall. A first electrode that electrically contacts the first doped layer and a second electrode that electrically contacts the second doped layer are formed. In the solar cell formed in this way, the first and second inclined sidewalls can improve the reflection of incident light, thereby improving the utilization rate of light by the solar cell and improving the efficiency of the cell.
[0118] Accordingly, other embodiments of the present disclosure also provide photovoltaic modules. The photovoltaic modules provided in other embodiments of the present disclosure will be described in detail below with reference to the drawings, but parts that are the same as or corresponding to those in the embodiments described above should be referred to the corresponding descriptions in the embodiments described above, and will not be described in detail below again.
[0119] Figure 19 is a schematic diagram of a photovoltaic module provided in one embodiment of the present disclosure.
[0120] Referring to Figure 19, the photovoltaic module includes a battery string in which a plurality of solar cells 300, formed by the solar cells described in the above embodiments or by the manufacturing method of the solar cells described in the above embodiments, 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 configuration to form a plurality of battery strings, and the plurality of battery strings are electrically connected in series and / or parallel.
[0121] Specifically, in some embodiments, multiple battery sheets are connected to each other by conductive strips 33 They may be electrically connected by 0. Figure 19 shows only one of the positional relationships between solar cells, namely, the arrangement direction of electrodes with the same polarity of the battery sheets is the same, in other words, all positive polarity electrodes of each battery sheet are arranged facing the same side, thereby each conductive strip 330 connects the different sides of two adjacent battery sheets. In some embodiments, the battery sheets may be arranged so that electrodes with different polarities face the same side, namely the electrodes of a plurality of adjacent battery sheets are arranged in the order of first polarity, second polarity, first polarity, respectively, thereby the conductive strip connects two adjacent battery sheets on the same side.
[0122] In some embodiments, there is no gap between the battery sheets; that is, the battery sheets may overlap each other.
[0123] In some embodiments, the sealing adhesive film 310 may include a first sealing layer covering either the front or back surface of the battery string, and a second sealing layer covering the other surface of the battery string. Specifically, at least one of the first or second sealing layer may be an organic sealing 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 and second sealing layers have boundaries before lamination, and once the photovoltaic module is formed after the lamination process, the concepts of the first and second sealing layers no longer exist; that is, the first and second sealing layers are formed as a single sealing layer 310.
[0125] In some embodiments, the cover 320 may be a light-transmitting cover such as a glass cover or a plastic cover. Specifically, the surface of the cover 320 facing the sealing 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 sealing layer and a second cover facing the second sealing layer.
[0126] Each of the embodiments described above is intended to realize specific examples of the Disclosure, and those skilled in the art will understand that various formal and detailed modifications can be made for actual application without departing from the spirit and scope of the Disclosure. Since any person skilled in the art can make changes and modifications without departing from the spirit and scope of the Disclosure, the scope of protection of the Disclosure shall be defined by the claims.
Claims
1. It is a solar cell, A substrate having opposing front and back surfaces, A first doped layer and a second doped layer are arranged alternately along a first direction on the back surface, wherein 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 the doping type 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 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 doped layer and the second doped layer, It includes a first electrode that is in electrical contact with the first doped layer, and a second electrode that is in electrical contact with the second doped layer, The first inclined sidewall includes a first sub-inclined sidewall, a platform surface, and a second sub-inclined sidewall, which are connected in order in a direction away from the back surface of the substrate. A solar cell characterized by the following features.
2. The angle between the first inclined sidewall and the surface of the first doped layer facing the back surface is an acute first angle, and the angle between the second inclined sidewall and the surface of the second doped layer facing the back surface is an acute second angle. The solar cell according to feature 1.
3. The aforementioned first angle is less than or equal to the second angle. The solar cell according to feature 2.
4. The aforementioned first angle is within the range of 25° to 60°. The aforementioned second angle is within the range of 30° to 65°. The solar cell according to feature 2.
5. The back surface exposed by the separation region has a pile structure, and the pile structure includes a plurality of pyramidal structures. The solar cell according to feature 1.
6. The width of the base of one of the pyramidal structures is 2 μm to 4 μm in the direction parallel to the back surface. The solar cell according to feature 5.
7. In a direction perpendicular to the back surface of the substrate, the distance between the surface of the first dope layer away from the substrate and the front surface of the substrate is greater than the distance between the surface of the second dope layer 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 dope layer away from the substrate. The solar cell according to feature 1.
8. In a direction perpendicular to the back 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 feature 1.
9. With respect to the back surface, the slope of the second sub-inclined side wall is greater than the slope of the first sub-inclined side wall. The solar cell according to feature 1.
10. The second inclined side wall is a continuous incline. The solar cell according to feature 1.
11. The dopant ions in the first doping layer include boron ions, and the dopant ions in the second doping layer include phosphorus ions. The solar cell according to feature 1.
12. A photovoltaic module, A solar cell according to any one of claims 1 to 11, comprising a plurality of electrically connected battery strings, A sealing adhesive film for covering the surface of the battery string, Includes a cover for covering the surface of the sealing adhesive film that is away from the battery string. A photovoltaic module characterized by the following features.