Solar cell and photovoltaic module

Abstract

The utility model provides a solar cell and a photovoltaic assembly, and relates to the field of photovoltaic technology. The solar cell comprises a silicon substrate, wherein the surface of the silicon substrate comprises a first region and a second region; the first area is provided with a first suede structure, and the second area is provided with a second suede structure; the vertex angle of the first suede structure is larger than that of the second suede structure; a passivation contact layer on the first region; and an electrode on the passivation contact layer. According to the solar cell, the passivation contact effect is better, the open-circuit voltage is larger, material waste can be reduced, light absorption can be increased, the light trapping effect is better, the short-circuit current can be further increased, and the photoelectric conversion efficiency of the solar cell is further improved.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaics, in particular to a solar cell and a photovoltaic component. Background Art

[0002] Solar cells can convert solar energy into electrical energy. They utilize clean energy and therefore have broad application prospects.

[0003] Providing a velvet structure in the silicon substrate of a solar cell can increase the anti-reflection effect. In existing solar cells, the size of the velvet structure at each position on the surface of the silicon substrate is the same.

[0004] However, in existing solar cells, the differences in anti-reflection effects and other effects required by the velvet structures at different positions are not taken into account. The sizes of the velvet structures at various positions on the surface of the silicon substrate are the same, making it difficult to take into account both the anti-reflection effects and other effects, thus affecting the cell performance. Utility Model Content

[0005] The utility model provides a solar cell and a photovoltaic module, aiming to solve the problem that in the existing solar cells, it is difficult to take into account both the anti-reflection effect and other effects on the basis of considering the velvet structure.

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

[0007] A silicon substrate, wherein the surface of the silicon substrate comprises: a first region and a second region; the first region has a first velvet structure, and the second region has a second velvet structure; the vertex angle of the first velvet structure is greater than the vertex angle of the second velvet structure; the first velvet structure comprises: a plurality of first-type pyramid structures; the first-type pyramid structure comprises: a first cone surface and a first cone vertex; the second velvet structure comprises: a plurality of second-type pyramid structures; the second-type pyramid structure comprises: a second cone surface and a second cone vertex;

[0008] a passivation contact layer located on the first region;

[0009] Electrode located on the passivation contact layer.

[0010] In the utility model, the passivation contact layer is only located in the first region, that is, a local passivation contact is formed, which can reduce the carrier recombination loss at the contact interface between the electrode and the silicon substrate, and reduce the shading, which can improve the performance of the solar cell. The vertex angle of the first velvet structure is greater than the vertex angle of the second velvet structure, that is, the first cone top of the first velvet structure is relatively flat, and the passivation contact layer prepared is thicker as a whole, and the thickness is more uniform, and the passivation contact effect is better, especially the thickness of the part of the passivation contact layer located at the first cone top is larger, and the electrode of the solar cell will preferentially contact the position where the first cone top of the first velvet structure in the first region is located. During the electrode sintering process, due to the thickness of the part of the passivation contact layer located at the first cone top, the part of the passivation contact layer located at the first cone top is not easy to be burned through, avoiding damage to the passivation contact layer, and reducing recombination, so that the local contact solar cell still has a good passivation contact effect, and the open circuit voltage of the solar cell is larger. Moreover, the vertex angle of the second velvet structure in the second region is smaller, the second velvet structure is sharper, has a better anti-reflection effect, and the short-circuit current of the solar cell is larger. That is to say, in the present application, on the one hand, it is ensured that the passivation contact performance of the first area is consistent with the actual passivation contact requirements, and the anti-reflection performance of each position is consistent with the actual anti-reflection requirements, which not only has a better passivation contact effect and a larger open-circuit voltage, but also can reduce material waste; on the other hand, the first velvet structure and the second velvet structure can increase the absorption of light and have a better light trapping effect, which can further increase the short-circuit current and further improve the photoelectric conversion efficiency of solar cells.

[0011] Optionally, the passivation contact layer includes: a first portion located on the top of the first cone, and a second portion located on the first cone surface;

[0012] The thickness of the first portion is greater than the thickness of the second portion.

[0013] Optionally, the undulation of the second conical surface is greater than the undulation of the first conical surface;

[0014] Alternatively, the roughness of the second conical surface is greater than the roughness of the first conical surface.

[0015] Optionally, an absolute value of a maximum difference between vertex angles of adjacent first suede structures is greater than an absolute value of a maximum difference between vertex angles of adjacent second suede structures.

[0016] Optionally, the reflectivity of the first velvet structure is greater than the reflectivity of the second velvet structure, and / or the difference between the reflectivity of the first velvet structure and the reflectivity of the second velvet structure is greater than or equal to 2%.

[0017] Optionally, the average vertex angle of the first suede structure is greater than or equal to 72°, and / or the average vertex angle of the second suede structure is less than or equal to 70°.

[0018] Optionally, the solar cell further comprises: a passivation anti-reflection layer located on the second region and the passivation contact layer;

[0019] The passivation anti-reflection layer includes: a third portion located on the second region, and a fourth portion located on the passivation contact layer;

[0020] The thickness of the third portion is smaller than the thickness of the fourth portion.

[0021] Optionally, the solar cell further comprises: a passivation anti-reflection layer located on the second region and the passivation contact layer;

[0022] The passivation anti-reflection layer comprises: a fifth portion located on the top of the first cone, and a sixth portion located on the first cone surface; the thickness of the fifth portion is greater than the thickness of the sixth portion.

[0023] Optionally, the solar cell further comprises: a passivation anti-reflection layer located on the second region and the passivation contact layer; the passivation anti-reflection layer comprises: a third portion located on the second region, and a fourth portion located on the passivation contact layer;

[0024] The thickness non-uniformity of the third part is greater than the thickness non-uniformity of the fourth part; the thickness non-uniformity of the third part is: the absolute value of the difference between two thicknesses at two positions along the same direction close to the second cone top in the part of the passivation anti-reflection layer located on the same second-type pyramid structure, divided by the sum of the two thicknesses; the thickness non-uniformity of the fourth part is: the absolute value of the difference between two thicknesses at two positions along the same direction close to the first cone top in the part of the passivation anti-reflection layer located on the same first-type pyramid structure, divided by the sum of the two thicknesses.

[0025] Optionally, the passivation contact layer includes: a tunneling oxide layer and a polysilicon layer which are stacked, and the tunneling oxide layer is close to the silicon substrate.

[0026] A second aspect of the present invention provides a photovoltaic assembly, comprising: a plurality of any of the aforementioned solar cells.

[0027] The present application not only ensures that the passivation contact performance at various locations of the solar cell is consistent with the actual passivation contact requirements, but also that the anti-reflection performance at various locations is consistent with the actual anti-reflection requirements, thereby improving the performance of the battery, and can increase the absorption of light, thereby achieving a better light trapping effect, further improving the short-circuit current, and at the same time reducing material waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments of the utility model will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A partial schematic diagram of the structure of a solar cell in an embodiment of the utility model is shown;

[0030] Figures 2 to 3 A schematic diagram of some preparation steps of a solar cell in an embodiment of the utility model is shown.

[0031] Description of the accompanying drawings:

[0032] 1-silicon substrate, 11-illustration of the first region, 2-tunneling oxide layer, 3-polysilicon layer, 4-passivation anti-reflection layer, 12-first cone top, 13-second cone top, 5-PSG layer, 6-illustration of the laser. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0034] The utility model provides a solar cell, referring to Figure 1 The solar cell may include: a silicon substrate 1, the silicon substrate 1 may be doped or intrinsic, which is not specifically limited. The silicon substrate 1 may be a single crystal silicon substrate, etc., which is not specifically limited. The surface of the silicon substrate 1 includes: a first region and a second region, and the relative sizes of the two regions are not specifically limited. Figure 1 In the embodiment, the area enclosed by 11 on the upper surface of the silicon substrate 1 is the first area, and the area not enclosed by 11 on the upper surface of the silicon substrate 1 is the second area. Figure 1 The first region has a first suede structure, and the second region has a second suede structure.

[0035] Figure 1 , Figures 2 to 3 It only represents the relative position relationship of each layer structure in the solar cell, and does not represent the relative size relationship of its actual size.

[0036] Reference Figure 1The first velvet structure includes: a plurality of first-type pyramid structures, and the first-type pyramid structures include: a first cone surface and a first cone top 12. Figure 1 The second velvet structure includes: a plurality of second-type pyramid structures, and the second-type pyramid structures include: a second cone surface and a second cone apex 13. The first cone apex 12 is the highest point in the first-type pyramid structure, and the second cone apex 13 is the highest point in the second-type pyramid structure. In the case where the highest part of the first-type pyramid structure is a plane formed by a plurality of points of equal height, the first cone apex 12 here can be the geometric center of the plane. In the case where the highest part of the second-type pyramid structure is a plane formed by a plurality of points of equal height, the second cone apex 13 here can be the geometric center of the plane. The side edges of a pyramid-like structure are the common edges of adjacent side surfaces in a pyramid-like structure. The cone surface of a pyramid-like structure is the collection of all side surfaces of the pyramid-like structure, that is, the part of the pyramid-like structure except the cone apex and the bottom surface, and the bottom surface refers to the surface opposite to the cone apex.

[0037] The apex angle of the first velvet structure is: the apex angle of the cross-section of the first velvet structure, which can be measured by a scanning electron microscope SEM. The apex angle of the second velvet structure is: the apex angle of the cross-section of the second velvet structure, which can be measured by a scanning electron microscope SEM. The apex angle of the first velvet structure is greater than the apex angle of the second velvet structure. The apex angle of the first velvet structure is larger, which means that the first cone top of the first velvet structure is flatter, and the second cone top of the second velvet structure is sharper.

[0038] The solar cell also includes: a passivation contact layer located on the first region, and an electrode located on the passivation contact layer. The passivation contact layer located only on the first region here plays a major role of selective passivation contact or local contact. The passivation contact layer is located only in the first region, which can reduce the carrier recombination loss at the contact interface between the electrode and the silicon substrate, and reduce shading, which can improve the performance of the solar cell. The vertex angle of the first velvet structure is greater than the vertex angle of the second velvet structure, that is, the first cone top is relatively flat, and the passivation contact layer prepared is thicker as a whole, and the thickness is more uniform, and the passivation effect is better, especially the thickness of the portion of the passivation contact layer located at the first cone top 12 is larger, and the electrode of the solar cell will preferentially contact the position of the first cone top of the first velvet structure in the first region. During the electrode sintering process, since the thickness of the portion of the passivation contact layer located at the first cone top 12 is larger, the portion of the passivation contact layer located at the first cone top 12 is not easy to be burned through, thereby avoiding damage to the passivation contact layer, and reducing recombination, so that the local contact solar cell still has a good passivation contact effect, and the open circuit voltage of the solar cell is larger. Moreover, the vertex angle of the second velvet structure in the second region is smaller, the second velvet structure is sharper, has a better anti-reflection effect, and the short-circuit current of the solar cell is larger. That is to say, in this application, the passivation contact layer on the first cone top of the first velvet structure in the first region needs to be thicker to avoid the passivation contact layer from being burned through during the electrode sintering process and to protect the passivation contact performance, while the second region does not need to be provided with an electrode and requires a good anti-reflection effect. Therefore, in this application, on the one hand, it can be ensured that the passivation contact performance of the first region is consistent with the actual passivation contact requirements, and the anti-reflection performance of each position, especially the second region, is consistent with the actual anti-reflection requirements, not only the passivation contact effect is better, the open circuit voltage is larger, and the material waste can be reduced; on the other hand, the first velvet structure and the second velvet structure can increase the absorption of light, have a better light trapping effect, can further increase the short-circuit current, and further improve the photoelectric conversion efficiency of the solar cell.

[0039] It should be noted that the vertex angle of the first velvet structure is greater than the vertex angle of the second velvet structure, and the difference between the two is not specifically limited. In the present application, the vertex angle of the first velvet structure is greater than the vertex angle of the second velvet structure, which can be understood as: each of the vertex angles of all the vertex angles of the first velvet structure is greater than each of the vertex angles of all the vertex angles of the second velvet structure. Alternatively, the vertex angle of the first velvet structure is greater than the vertex angle of the second velvet structure, which can be understood as: each of the first preset ratio of the total number of all the vertex angles of the first velvet structure is greater than each of the second preset ratio of the total number of all the vertex angles of the second velvet structure. The first preset ratio and the second preset ratio here can both be greater than or equal to 50%, and the first preset ratio and the second preset ratio can be equal or unequal, and there is no specific limitation on this. For example, each of the 50% vertex angles of the total number of all the vertex angles of the first velvet structure is greater than each of the 50% vertex angles of the total number of all the vertex angles of the second velvet structure. For example, each of the 55% vertices of the total number of all vertices of the first suede structure is greater than each of the 55% vertices of the total number of all vertices of the second suede structure. For another example, each of the 60% vertices of the total number of all vertices of the first suede structure is greater than each of the 60% vertices of the total number of all vertices of the second suede structure. For another example, each of the 65% vertices of the total number of all vertices of the first suede structure is greater than each of the 65% vertices of the total number of all vertices of the second suede structure. For another example, each of the 70% vertices of the total number of all vertices of the first suede structure is greater than each of the 70% vertices of the total number of all vertices of the second suede structure. For another example, each of the 75% vertices of the total number of all vertices of the first suede structure is greater than each of the 75% vertices of the total number of all vertices of the second suede structure. For another example, each of the 80% vertices of the total number of all vertices of the first suede structure is greater than each of the 80% vertices of the total number of all vertices of the second suede structure. For another example, each of the 85% vertices of the total number of all vertices of the first suede structure is greater than each of the 85% vertices of the total number of all vertices of the second suede structure. For another example, each of the 90% vertices of the total number of all vertices of the first suede structure is greater than each of the 90% vertices of the total number of all vertices of the second suede structure. For another example, each of the 95% vertices of the total number of all vertices of the first suede structure is greater than each of the 95% vertices of the total number of all vertices of the second suede structure.For another example, each of the 99.3% vertices of the total number of all vertices of the first suede structure is greater than each of the 99% vertices of the total number of all vertices of the second suede structure. For another example, each of the 50% vertices of the total number of all vertices of the first suede structure is greater than each of the 53% vertices of the total number of all vertices of the second suede structure. For another example, each of the 60% vertices of the total number of all vertices of the first suede structure is greater than each of the 55% vertices of the total number of all vertices of the second suede structure. For another example, each of the 83% vertices of the total number of all vertices of the first suede structure is greater than each of the 85% vertices of the total number of all vertices of the second suede structure. For another example, each of the 97% vertices of the total number of all vertices of the first suede structure is greater than each of the 96.2% vertices of the total number of all vertices of the second suede structure.

[0040] For another example, the vertex angles in the first suede structure are 75.313°, 77.805°, 63.607°, and 80.722°, respectively. The vertex angles in the second suede structure are 67.863°, 66.115°, 70.376°, and 69.467°, respectively. Three of the above four vertex angles in the first suede structure are greater than the above four vertex angles in the second suede structure.

[0041] It should be noted that the total number of all vertex angles in the second velvet structure may be greater than the total number of all vertex angles in the first velvet structure. Here, the light-facing surface of the silicon substrate may include: a first region and a second region, or both the light-facing surface and the backlight surface of the silicon substrate may include: a first region and a second region, or the backlight surface of the silicon substrate may include: a first region and a second region. During normal operation of the solar cell, the surface of the silicon substrate that mainly receives light is the light-facing surface, and the backlight surface is opposite to the light-facing surface.

[0042] Optional, see Figure 1 , Figures 2 to 3, the passivation contact layer may include: a stacked tunneling oxide layer 2 and a polysilicon layer 3, wherein the tunneling oxide layer 2 is close to the silicon substrate 1. The polysilicon layer 3 here may be a doped polysilicon layer, wherein the doping element may be P-type or N-type, which is not specifically limited. Specifically, the stacked tunneling oxide layer 2 and the polysilicon layer 3 located only in the first region here play the main role of selective passivation contact or local contact. The stacked tunneling oxide layer 2 and the polysilicon layer 3 are only located in the first region, which can reduce the carrier recombination loss at the contact interface between the electrode and the silicon substrate, and reduce shading, which can improve the performance of the solar cell. Normally, the thickness of the tunneling oxide layer 2 is relatively thin, and the apex angle of the first velvet structure is greater than the apex angle of the second velvet structure, that is, the first cone top is relatively flat, and the prepared polysilicon layer 3 is thicker as a whole, and the thickness is more uniform, and the passivation effect is better, especially the thickness of the portion of the polysilicon layer 3 located at the first cone top 12 is relatively large, and the electrode of the solar cell will preferentially contact the position where the first cone top of the first velvet structure in the first area is located. During the electrode sintering process, since the thickness of the portion of the polysilicon layer 3 located at the first cone top 12 is relatively large, the portion of the polysilicon layer 3 located at the first cone top 12 is not easily burned through, thereby avoiding damage to the tunneling oxide layer 3, especially avoiding damage to the tunneling oxide layer located at the first cone top 12, so that the local contact solar cell still has a good tunneling contact effect. That is to say, in the present application, the polysilicon layer 3 on the first cone top of the first velvet structure in the first region needs to have a larger thickness to prevent the tunneling oxide layer 2 from being burned through during the electrode sintering process and to protect the tunneling passivation performance. Therefore, in the present application, it can be ensured that the passivation tunneling performance of the first region is consistent with the actual passivation tunneling requirements, the passivation tunneling effect is better, and material waste can be reduced.

[0043] Optionally, the passivation contact layer includes: a first portion located on the first cone top 12, and a second portion located on the first cone surface, and the thickness of the first portion is greater than the thickness of the second portion. Specifically, the thickness of the first portion of the passivation contact layer located at the first cone top 12 is greater than the thickness of the second portion located on the first cone surface, and the thickness of the first portion of the passivation contact layer located at the first cone top 12 is greater. Since the electrode of the solar cell will preferentially contact the position where the first cone top of the first velvet structure of the first region is located, during the electrode sintering process, the thickness of the portion of the passivation contact layer located at the first cone top 12 is greater, so the portion of the passivation contact layer located at the first cone top 12 is not easily burned through, thereby avoiding damage to the passivation contact layer, reducing recombination, and especially avoiding damage to the passivation contact layer located at the first cone top 12, so that the local contact solar cell still has a good passivation contact effect, and the open circuit voltage of the solar cell is relatively large. It should be noted that, in the case where the passivation contact layer includes: a tunneling oxide layer 2 and a polysilicon layer 3 arranged in a stacked manner, the thickness of the portion of the polysilicon layer 3 located at the first cone top 12 is greater than the thickness of the portion located on the first cone surface. Normally, the thickness of the tunneling oxide layer 2 is relatively thin. During the electrode sintering process, the thickness of the portion of the polysilicon layer 3 located at the first cone top 12 is relatively large, so the portion of the polysilicon layer 3 located at the first cone top 12 is not easily burned through, thereby avoiding damage to the tunneling oxide layer, especially avoiding damage to the tunneling oxide layer located at the first cone top 12, so that the local contact solar cell still has a good tunneling passivation effect. It should be noted that, in the case where the passivation contact layer includes: a tunneling oxide layer 2 and a polysilicon layer 3 arranged in a stacked manner, the contents here are correspondingly adapted in the entire text of this application, and similar effects can be achieved. In order to avoid repetition, the relevant parts will not be repeated.

[0044] It should be noted that, on the basis that the thickness of the first part is greater than the thickness of the second part, the difference between the two is not specifically limited. The thickness of all film layers mentioned in this application can be measured using a thickness measuring tool such as an ellipsometer, and the measuring method is not specifically limited.

[0045] The undulation mainly refers to the degree of undulation caused by relatively large high and low structures on the surface, and the roughness refers to the degree of unevenness caused by micro-protrusions / micro-depressions on the surface. Optionally, the undulation of the second conical surface is greater than the undulation of the first conical surface; or, the roughness of the second conical surface is greater than the roughness of the first conical surface. In one case, the number of protrusions and / or depressions on the second cone surface of the second type of pyramidal structure may be greater than the number of protrusions and / or depressions on the first cone surface of the first type of pyramidal structure; in another case, the degree of protrusions and / or depressions on the second cone surface of the second type of pyramidal structure may be greater than the degree of protrusions and / or depressions on the first cone surface of the first type of pyramidal structure; in another case, the arrangement of protrusions and / or depressions on the second cone surface of the second type of pyramidal structure may be more disorderly than the arrangement of protrusions and / or depressions on the first cone surface of the first type of pyramidal structure; in another case, the height of the protrusions and / or the depth of the depressions on the second cone surface of the second type of pyramidal structure may be greater than the height of the protrusions and / or the depth of the depressions on the first cone surface of the first type of pyramidal structure; furthermore, the morphology of the second cone surface of the second type of pyramidal structure is more irregular, so that the second velvet structure has a larger specific surface area, lower reflectivity, better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. Moreover, the first cone surface of the first type of pyramid structure is smoother, which is conducive to the preparation of a thicker and more uniform passivation contact layer. During the electrode sintering process, the thickness of the portion of the passivation contact layer located at the first cone top 12 is relatively large, so the portion of the passivation contact layer located at the first cone top 12 is not easily burned through, thereby avoiding damage to the passivation contact layer and reducing recombination, especially avoiding damage to the passivation contact layer located at the first cone top 12, so that the local contact solar cell still has a good passivation contact effect, and the open circuit voltage of the solar cell is relatively large.

[0046] Optionally, the absolute value of the maximum difference of the vertex angles of the adjacent first velvet structures is greater than the absolute value of the maximum difference of the vertex angles of the adjacent second velvet structures, that is, the uniformity of the vertex angles of the second velvet structure is better than the uniformity of the vertex angles of the first velvet structure, and the second velvet structure is sharper, so that the second velvet structure has a larger specific surface area, that is, the second region has a larger specific surface area, lower reflectivity, better light trapping effect, can increase short-circuit current, and ultimately improve the photoelectric conversion efficiency of solar cells. The vertex angles of the adjacent first velvet structures refer to: the two vertex angles closest to each other in the first velvet structure. The absolute value of the maximum difference of the vertex angles of the adjacent first velvet structures: refers to selecting the vertex angles of the first preset number of pairs of adjacent first velvet structures from the first velvet structure, and the first preset number of pairs of adjacent first velvet structures The vertex angles of the adjacent two first velvet structures are subtracted, and the first preset number of differences are obtained, and then the maximum absolute value is selected from the absolute values ​​of the first preset number of differences. The vertex angles of the adjacent second velvet structures refer to: the two vertex angles closest to each other in the second velvet structure. The absolute value of the maximum difference between the vertex angles of adjacent second velvet structures: refers to selecting a second preset number of pairs of vertex angles of two adjacent second velvet structures from the second velvet structure, and among the second preset number of pairs of vertex angles of two adjacent second velvet structures, the vertex angles of two adjacent second velvet structures are subtracted to obtain a second preset number of differences, and then the largest absolute value is selected from the absolute values ​​of the second preset number of differences.

[0047] It should be noted that whether the first preset number and the second preset number are equal is not limited, and the two may be equal or unequal. The first preset number and the second preset number may be selected according to actual needs. For example, the first preset number and the second preset number may both be greater than or equal to 3. For another example, the first preset number and the second preset number may both be greater than or equal to 5. The absolute value of the maximum difference between the vertex angles of adjacent first suede structures and the absolute value of the maximum difference between the vertex angles of adjacent second suede structures are not specifically limited.

[0048] Optionally, the reflectivity of the first velvet structure is greater than the reflectivity of the second velvet structure, and the difference between the reflectivity of the first velvet structure and the reflectivity of the second velvet structure is greater than or equal to 2%. The reflectivity of the second velvet structure is smaller, that is, the reflectivity of the second region is smaller, and the light trapping effect is better, which can further increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell.

[0049] For example, the reflectivity of the second velvet structure is 8%, and the reflectivity of the first velvet structure is 11%. For another example, the reflectivity of the first velvet structure is greater than the reflectivity of the second velvet structure, and the difference between the two is 2%, or 2.3%, or 2.7%, or 2.5%, or 3%, or 3.1%, or 3.3%, or 3.5%.

[0050] Optionally, the average vertex angle of the first velvet structure is greater than or equal to 72°, and / or the average vertex angle of the second velvet structure is less than or equal to 70°. The average vertex angle of the first velvet structure is larger, the first velvet structure is relatively flat, especially the first cone top is flatter, then the thickness of the first part of the passivation contact layer located at the first cone top 12 is larger, because the electrode of the solar cell will preferentially contact the position of the first cone top of the first velvet structure in the first region, during the electrode sintering process, the thickness of the part of the passivation contact layer located at the first cone top 12 is larger, so the part of the passivation contact layer located at the first cone top 12 is not easy to be burned through, avoiding damage to the passivation contact layer, reducing recombination, especially avoiding damage to the passivation contact layer located at the first cone top 12, so that the local contact solar cell still has a good passivation contact effect, and the open circuit voltage of the solar cell is larger. The average vertex angle of the second velvet structure is smaller, the second velvet structure is sharper, the reflectivity is smaller, that is, the reflectivity of the second region is smaller, the light trapping effect is better, the short-circuit current can be further increased, and the photoelectric conversion efficiency of the solar cell is finally improved.

[0051] For example, the average vertex angle of the first velvet structure can be 74.99°, 75°, 77°, 78°, 80°, 81.3°, 74.5°, 74.4°, 74.02°, 73.59°, 73.11°, 72.5°, 72.01°, or 72°.

[0052] For example, the average vertex angle of the second velvet structure may be 70°, 69°, 67°, 68°, 68.5°, 60°, 61.3°, 64.5°, 54.02°, 53.9°, 58.11°, 64.3°, 67.9°, or 55°.

[0053] It should be noted that the average vertex angle of the first velvet structure refers to: the arithmetic mean of all vertex angles of the first velvet structure, or may refer to the arithmetic mean of the third preset ratio of the total number of all vertex angles of the first velvet structure, and the third preset ratio here may be greater than or equal to 50%. The average vertex angle of the second velvet structure refers to: the arithmetic mean of all vertex angles of the second velvet structure, or may refer to the arithmetic mean of the fourth preset ratio of the total number of all vertex angles of the second velvet structure, and the fourth preset ratio here may be greater than or equal to 50%. The third preset ratio and the fourth preset ratio here may be equal or different, and there is no specific limitation on this.

[0054] The first type of pyramid structure of the first velvet structure also includes: a first bottom contour line away from the first cone top, and the width of the first type of pyramid structure is the maximum inner dimension of the first bottom contour line of the first type of pyramid structure, and the second type of pyramid structure also includes: a second bottom contour line away from the second cone top, and the width of the second type of pyramid structure is the maximum inner dimension of the bottom contour line of the second type of pyramid structure. The width of the first type of pyramid structure is greater than the width of the second type of pyramid structure, and the height of the first type of pyramid structure is greater than the height of the second type of pyramid structure, that is, the size of the first type of pyramid structure is greater than the size of the second type of pyramid structure, and then the size of the first velvet structure is greater than the size of the second velvet structure, and then the number of the first type of pyramid structures in the first region is small, the number of the first cone top is also small, and the first cone top is relatively flat, so that the protection effect on the passivation contact layer during the sintering process of the electrode is stronger, and the passivation contact layer can be further avoided from being damaged, especially the passivation contact layer located at the first cone top 12 is avoided, and the recombination is less, so that the local contact solar cell still has a good passivation contact effect, and the open circuit voltage of the solar cell is large. Here, the height and width of each first-class pyramid structure can be greater than the height and width of each second-class pyramid structure, or greater than or equal to 50% of the height and width of the first-class pyramid structures, both greater than the height and width of each second-class pyramid structure, or greater than or equal to 50% of the height and width of the first-class pyramid structures, both greater than, greater than or equal to 50% of the height and width of the second-class pyramid structures, and there is no specific limitation on this.

[0055] For example, the height of the first type of pyramid structure can be: 1.575um (micrometer), 1.549um, the height of the second type of pyramid structure can be: 939.96nm (nanometer), 740.10nm, the above heights of the first type of pyramid structure are greater than the above heights of the second type of pyramid structure. For example, the width of the first type of pyramid structure can be: 2.081um, the width of the first type of pyramid structure can also be: 1.963um, 1.588um, 1.476um, 1.321um, 1.715um, 1.454um, 1.391um, 1.402um, 1.186um. For example, the width of the second type of pyramid structure can be: 750.81nm, 804nm, 808.75nm, 900.64nm, 934.61nm, 909.32nm, 946.20nm, 844.86nm, 898.51nm, 985.40nm. The width of the first type of pyramid structure is greater than the width of the second type of pyramid structure. For another example, the average width of the first type of pyramid structure is 1.50um, and the average height is 1.74um or 1.7um, while the average width of the second type of pyramid structure is 0.880um or 0.8um, and the average height is 0.84um or 0.8um. ​​The size of the second type of pyramid structure is smaller and more uniform.

[0056] Optional, see Figure 1 , the solar cell also includes: a passivation anti-reflection layer 4 located in the second region and on the passivation contact layer. The passivation anti-reflection layer 4 includes: a third part located in the second region, and a fourth part located in the passivation contact layer, and the thickness of the third part is less than the thickness of the fourth part. Specifically, on the one hand, the greater the thickness of the passivation anti-reflection layer, the better the passivation effect, but the anti-reflection effect weakens as its thickness increases, that is, the thicker the portion of the passivation anti-reflection layer 4 located in the first region, the better the passivation effect, which can improve its open circuit voltage, while the thickness of the passivation anti-reflection layer 4 located in the second region is thinner, and the anti-reflection effect is better, and the light trapping effect is better, which can further improve the short-circuit current, and finally improve the photoelectric conversion efficiency of the solar cell. On the other hand, the thicker portion of the passivation anti-reflection layer 4 located in the first region also helps to protect the passivation contact layer during the sintering process of the electrode, which can further avoid damaging the passivation contact layer, especially avoiding damaging the passivation contact layer located at the first cone top 12, so that the local contact solar cell still has a good passivation contact effect, and the open circuit voltage of the solar cell is relatively large.

[0057] Optionally, the thickness non-uniformity of the third part is greater than the thickness non-uniformity of the fourth part; the thickness non-uniformity of the fourth part is: the absolute value of the difference between two thicknesses at two positions along the same direction close to the first cone top 12 in the part of the passivation anti-reflection layer 4 located on the same first-class pyramid structure, divided by the sum of the two thicknesses. The two positions here are defined as any two positions along the same direction close to the first cone top 12. For example, the three first-class pyramid structures in the first velvet structure are the first-class pyramid structure on the left, the first-class pyramid structure in the middle, and the first-class pyramid structure on the right. In the three first-class pyramid structures in the first velvet structure, the thickness non-uniformity of the fourth part can be: the absolute value of the difference between two thicknesses at two positions along the same direction close to the first cone top in the left part of the first-class pyramid structure on the left side of the front passivation anti-reflection layer 4, divided by the sum of the two thicknesses. For another example, in the three first-class pyramid structures in the first velvet structure, the thickness unevenness of the fourth part may be: in the right part of the first cone top on the left first-class pyramid structure in the front passivation anti-reflection layer 4, the absolute value of the difference between two thicknesses at two positions along the same direction close to the first cone top, divided by the sum of the two thicknesses. For another example, in the three first-class pyramid structures in the first velvet structure, the thickness unevenness of the fourth part may be: in the left part of the first cone top on the middle first-class pyramid structure in the front passivation anti-reflection layer 4, the absolute value of the difference between two thicknesses at two positions along the same direction close to the first cone top, divided by the sum of the two thicknesses. For another example, in the three first-class pyramid structures in the first velvet structure, the thickness unevenness of the fourth part may be: in the right part of the first cone top on the middle first-class pyramid structure in the front passivation anti-reflection layer 4, the absolute value of the difference between two thicknesses at two positions along the same direction close to the first cone top, divided by the sum of the two thicknesses. For another example, in the three first-type pyramid structures in the first velvet structure, the thickness unevenness of the fourth part may be: in the left part of the first cone top on the first-type pyramid structure on the right side in the front passivation anti-reflection layer 4, the absolute value of the difference between two thicknesses at two positions along the same direction close to the first cone top, divided by the sum of the two thicknesses. For another example, in the three first-type pyramid structures in the first velvet structure, the thickness unevenness of the fourth part may be: in the right part of the first cone top on the first-type pyramid structure on the right side in the front passivation anti-reflection layer 4, the absolute value of the difference between two thicknesses at two positions along the same direction close to the first cone top, divided by the sum of the two thicknesses.

[0058] The thickness non-uniformity of the third part is: the absolute value of the difference between two thicknesses at two positions in the same direction close to the second cone top 13 of the passivation anti-reflection layer in the part located on the same second type pyramid structure, divided by the sum of the two thicknesses, where the two positions are defined in the same direction close to the second cone top 13. The thickness non-uniformity of the third part here corresponds to the example described in the thickness non-uniformity of the fourth part in the three first type pyramid structures in the first velvet structure.

[0059] That is, if the thickness of the fourth portion of the passivation anti-reflection layer 4 located on the first region is more uniform, then the thickness of the fourth portion of the passivation anti-reflection layer 4 located on the first region is thicker, which can achieve better passivation contact effect, especially the thickness of the portion of the passivation contact layer located at the first cone top 12 is larger, and the electrode of the solar cell will preferentially contact the position of the first cone top of the first velvet structure in the first region. During the electrode sintering process, the thickness of the portion of the passivation contact layer located at the first cone top 12 is larger, so the portion of the passivation contact layer located at the first cone top 12 is not easy to be burned through, avoiding damage to the passivation contact layer, and reducing recombination, especially avoiding damage to the passivation contact layer located at the first cone top 12, so that the local contact solar cell still has a good passivation contact effect, and the open circuit voltage of the solar cell is larger. The thickness of the third portion of the passivation anti-reflection layer 4 located on the second region is more uneven, and after the light enters the passivation anti-reflection layer with different thicknesses, the light path of the light will change more times, which can increase the optical path. In combination with the velvet structure of the present application, the absorption of light can be further increased, and the light trapping effect is better.

[0060] It should be noted that, when the thickness unevenness of the third part is greater than the thickness unevenness of the fourth part, the size of the difference between the two is not specifically limited. The passivation anti-reflection layer 4 of the present application can play a passivation role and can also play an anti-reflection role. The material of the passivation anti-reflection layer 4 can be selected from: silicon oxide, and / or silicon oxynitride, etc., and the specific material of the passivation anti-reflection layer 4 is not limited. The passivation anti-reflection layer 4 can be prepared by PECVD (Plasma Enhanced Chemical Vapor Deposition) and other methods, and the specific preparation method of the passivation anti-reflection layer is not specifically limited.

[0061] Optionally, the passivation anti-reflection layer 4 includes: a fifth part located on the first cone top 12, and a sixth part located on the first cone surface, the thickness of the fifth part is greater than the thickness of the sixth part, that is, the thickness of the passivation anti-reflection layer located on the first cone top of the first velvet structure is larger, and the electrode of the solar cell will preferentially contact the position of the first cone top of the first velvet structure in the first region, and because during the sintering process of the electrode, the thicker fifth part located at the first cone top can further avoid damaging the passivation contact layer, especially avoiding damaging the passivation contact layer located at the first cone top 12, so that the local contact solar cell still has a good passivation contact effect, and the open circuit voltage of the solar cell is relatively large.

[0062] The present application also provides a photovoltaic module, which includes: a plurality of any of the aforementioned solar cells, the number of solar cells in the photovoltaic module is not specifically limited, the photovoltaic module may also include a packaging film located on both sides of the solar cell, and other structures of the photovoltaic module are not specifically limited. The photovoltaic module has the same or similar beneficial effects as any of the aforementioned solar cells, and in order to avoid repetition, it will not be described here.

[0063] The present application is further explained below with reference to specific embodiments.

[0064] Example

[0065] like Figure 2 , texturing is performed on an N-type silicon substrate 1 to form a first velvet structure. The apex angle of the first velvet structure is relatively large, the first cone top of the first velvet structure is relatively flat, and the size of the first velvet structure is relatively large. Then, a tunneling oxide layer 2 and an amorphous silicon layer are sequentially prepared on the first velvet structure. Since the first cone top of the first velvet structure is relatively flat, the prepared tunneling oxide layer 2 and the amorphous silicon layer, especially the amorphous silicon layer, are thicker and more uniform in thickness, and the subsequently formed polycrystalline silicon layer is thicker and more uniform in thickness. The amorphous silicon layer is phosphorus-doped to obtain a phosphorus-doped polycrystalline silicon layer 3, and a PSG (phosphorus silicon glass) thin layer is generated on the surface of the polycrystalline silicon layer 3, which is the portion indicated by the number 5 in the figure, and the PSG layer 5 can protect the polycrystalline silicon layer 3 from being etched by alkali. A graphical method is used to illuminate the second area with a laser 6 to destroy the PSG layer in the second area, such as Figure 3As shown, the method can selectively retain the PSG layer 5 in the first region to protect the polysilicon layer 3, the tunnel oxide layer 2 and the first velvet structure in the first region from being etched. Currently commonly used alkaline etching may cause the PSG layer to have poor protection for the polysilicon layer 3 on the first region, causing damage to the structure. The present application uses a special alkaline solution to texture the patterned structure. The alkaline solution can meet the requirements of the PSG layer for protecting the polysilicon layer 3 on the first region, and can also achieve secondary texture of the second region or non-contact region. The alkaline solution sequentially etches the polysilicon layer and the tunnel oxide layer on the second region, exposing the second region of the silicon substrate, and then performs secondary texture on the second region, so that the size of the second velvet structure in the second region is smaller, the top angle of the second velvet structure is smaller, and the second velvet structure is sharper. Finally, the deposition passivation is performed. When the anti-reflection layer 4 is formed, the thickness of the fifth part on the first cone top in the passivation anti-reflection layer 4 located on the first region is greater than the thickness of the sixth part on the first cone surface in the passivation anti-reflection layer 4, which is beneficial to improving the passivation of the battery. The electrode of the solar cell will preferentially contact the position of the first cone top of the first velvet structure in the first region, and because during the sintering process of the electrode, the thicker polysilicon layer and the fifth part located at the first cone top can further avoid damaging the tunneling oxide layer, especially avoiding damaging the tunneling oxide layer located at the first cone top 12, so that the local contact solar cell still has a good passivation tunneling effect, and the open circuit voltage of the solar cell is relatively large. Moreover, the top angle of the second velvet structure on the second region is smaller and sharper, and the thickness of the passivation anti-reflection layer 4 deposited thereon is also thinner, so it has a better anti-reflection effect and a better light trapping effect, which can further increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The structure obtained after depositing the passivation anti-reflection layer 4 is as follows: Figure 1 As shown, electrodes etc. are then prepared.

[0066] The application mentioned herein uses a specially prepared alkali solution with a concentration of 1% to 5%, a special additive concentration range of 0.3% to 1.5%, and a hydrogen peroxide concentration range of 1% to 10%.

[0067] Comparative Example

[0068] In the comparative example, only one texturing process is performed, that is, the texturing is performed directly on the N-type silicon substrate, and the top angles and sizes of the textured structures on the first and second regions obtained by texturing are the same. Then, a tunneling oxide layer and an amorphous silicon layer are sequentially prepared on the silicon substrate after texturing, and the amorphous silicon layer is phosphorus-doped to obtain a phosphorus-doped polycrystalline silicon layer, and a layer of PSG is generated on the surface of the polycrystalline silicon layer 3. The PSG on the second region is removed to expose the second region, and a passivation anti-reflection layer is deposited, and then electrodes are prepared.

[0069] In the comparative example, if the apex angle of the prepared velvet structure is small, the cone top is sharper, and the thickness of the polysilicon layer 3 formed on the first region is small. During the electrode sintering process, the tunneling oxide layer at the cone top of the velvet structure in the first region will be damaged, resulting in a larger recombination. If the size of the velvet structure prepared in the comparative example is large, it cannot meet the anti-reflection requirements of the second region. If the size of the velvet structure prepared in the comparative example is small, the number of cone tops in the first region is large, and the thickness of the polysilicon layer 3 formed on the first region is small. During the electrode sintering process, the tunneling oxide layer at the cone top of the velvet structure in the first region will be damaged, resulting in a larger recombination.

[0070] Under the same test conditions, the battery performance of the embodiment and the comparative example is tested, specifically, an IV test (current voltage characteristic curve test) can be performed. Compared with the comparative example, the efficiency of the embodiment is improved by about 0.3%, mainly in terms of voltage. Due to the flatter first cone top and the larger velvet structure on the first region, it is conducive to preparing a thicker polysilicon layer and a thicker passivation anti-reflection layer at the first cone top of the first velvet structure in the first region. During the electrode sintering process, the probability of the tunneling oxide layer being damaged is greatly reduced, which helps to reduce the damage to the metal, resulting in fewer defects, and a decrease in metal recombination, which helps to improve the passivation, and its opening voltage is improved by 2.5mV (millivolt). On the other hand, the vertex angle of the second velvet structure on the second region is smaller, sharper, and has a larger specific surface area. The passivation anti-reflection layer on the second region is thinner, and the anti-reflection effect is better, which is conducive to the absorption of light, excitation of more photogenerated carriers, and generation of more current and current collection. Its short current is improved by 0.06mA (milliamperes), and then the FF (filler) will be improved by about 1%.

[0071] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0072] The embodiments of the utility model are described above in conjunction with the accompanying drawings, but the utility model is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the utility model, ordinary technicians in this field can also make many forms without departing from the scope of protection of the utility model and the claims, all of which are within the protection of the utility model.

Claims

1. A solar cell, characterized in that: include: A silicon substrate, wherein the surface of the silicon substrate comprises: a first region and a second region; the first region has a first velvet structure, and the second region has a second velvet structure; the vertex angle of the first velvet structure is greater than the vertex angle of the second velvet structure; the first velvet structure comprises: a plurality of first-type pyramid structures; the first-type pyramid structure comprises: a first cone surface and a first cone vertex; the second velvet structure comprises: a plurality of second-type pyramid structures; the second-type pyramid structure comprises: a second cone surface and a second cone vertex; a passivation contact layer located on the first region; Electrode located on the passivation contact layer.

2. The solar cell according to claim 1, characterized in that The passivation contact layer includes: a first portion located on the top of the first cone, and a second portion located on the first cone surface; The thickness of the first portion is greater than the thickness of the second portion.

3. The solar cell according to claim 1, characterized in that The undulation of the second conical surface is greater than the undulation of the first conical surface; Alternatively, the roughness of the second conical surface is greater than the roughness of the first conical surface.

4. The solar cell according to claim 1, characterized in that The absolute value of the maximum difference between the vertex angles of adjacent first suede structures is greater than the absolute value of the maximum difference between the vertex angles of adjacent second suede structures.

5. The solar cell according to claim 1, characterized in that: The reflectivity of the first velvet structure is greater than the reflectivity of the second velvet structure, and / or the difference between the reflectivity of the first velvet structure and the reflectivity of the second velvet structure is greater than or equal to 2%.

6. The solar cell according to claim 1, characterized in that The average vertex angle of the first suede structure is greater than or equal to 72°, and / or the average vertex angle of the second suede structure is less than or equal to 70°.

7. The solar cell according to any one of claims 1 to 6, characterized in that: Also includes: a passivation anti-reflection layer located on the second region and the passivation contact layer; The passivation anti-reflection layer includes: a third portion located on the second region, and a fourth portion located on the passivation contact layer; The thickness of the third portion is smaller than the thickness of the fourth portion.

8. The solar cell according to any one of claims 1 to 6, characterized in that: Also includes: a passivation anti-reflection layer located on the second region and the passivation contact layer; The passivation anti-reflection layer includes: a fifth portion located on the top of the first cone, and a sixth portion located on the first cone surface; The thickness of the fifth portion is greater than the thickness of the sixth portion.

9. The solar cell according to any one of claims 1 to 6, characterized in that: Also includes: a passivation anti-reflection layer located on the second region and the passivation contact layer; The passivation anti-reflection layer includes: a third portion located on the second region, and a fourth portion located on the passivation contact layer; The thickness non-uniformity of the third part is greater than the thickness non-uniformity of the fourth part; the thickness non-uniformity of the third part is: the absolute value of the difference between two thicknesses at two positions along the same direction close to the second cone top in the part of the passivation anti-reflection layer located on the same second-type pyramid structure, divided by the sum of the two thicknesses; the thickness non-uniformity of the fourth part is: the absolute value of the difference between two thicknesses at two positions along the same direction close to the first cone top in the part of the passivation anti-reflection layer located on the same first-type pyramid structure, divided by the sum of the two thicknesses.

10. The solar cell according to any one of claims 1 to 6, characterized in that: The passivation contact layer includes: a tunneling oxide layer and a polysilicon layer which are stacked, and the tunneling oxide layer is close to the silicon substrate.

11. A photovoltaic module, characterized in that: include: A solar cell as claimed in any one of claims 1 to 10.

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