Photovoltaic cell and photovoltaic module

Abstract

In the invention, at least one surface of the cell main body of the photovoltaic cell comprises the first area and the second area, the first area is arranged to be the suede structure, and the suede structure composed of the pyramid and / or inverted pyramid structure can reduce the probability that small-angle incident light is reflected out of the photovoltaic cell; the second area is arranged to be a plurality of mutually independent pits on the surface of the cell main body, the plurality of micron-sized pits can reduce the probability that large-angle incident light is reflected out of the photovoltaic cell, the large-angle incident light is reflected for multiple times in the micron-sized pits, the absorption effect of the photovoltaic cell on the incident light can be improved, and meanwhile, the absorption effect of the photovoltaic cell on the incident light can be improved. Compared with a nano-scale light trapping structure, the structure size of the micron-scale pits is larger, and the surface area of the photovoltaic cell with the micron-scale pits is smaller, so that a uniform passivation layer can be effectively generated on the surface of the photovoltaic cell, meanwhile, the recombination rate of unbalanced carriers on the surface of the photovoltaic cell is reduced, and the photoelectric conversion efficiency of the photovoltaic cell is improved. And the photoelectric conversion efficiency of the photovoltaic cell is further improved.

Description

[0001] This application is a divisional application of application number 202011296656.4, and the invention title is "A photovoltaic cell and photovoltaic module". The application date of the patent application with application number 202011296656.4 is November 18, 2020. Technical Field

[0002] The present application relates to the field of solar cells, and in particular to a photovoltaic cell, a preparation method and a photovoltaic module. Background Art

[0003] With the continuous consumption of traditional energy and its negative impact on the environment, the development and utilization of solar energy as a pollution-free, renewable energy has developed rapidly, especially photovoltaic cells with high conversion efficiency have become the focus of current research.

[0004] At present, a pyramid and / or inverted pyramid-shaped velvet structure can be prepared on the surface of a photovoltaic cell through a velvet process to reduce the reflection of sunlight on the surface of the photovoltaic cell, so that the photovoltaic cell can absorb more sunlight for photoelectric conversion, thereby improving the conversion efficiency of the photovoltaic cell. This structure has a good anti-reflection effect on direct light or light with a small incident angle, but for light with a large incident angle, a large part of the light will be reflected back into the air from the surface of the photovoltaic cell after passing through the pyramid and / or inverted pyramid-shaped velvet structure on the surface of the photovoltaic cell, and will not participate in the photoelectric conversion of the photovoltaic cell. In the prior art, a nanoscale light-trapping structure can be prepared on the surface of a photovoltaic cell through a black silicon process. The nanoscale light-trapping structure has a good light-trapping effect on light incident at a large angle, thereby improving the photoelectric conversion rate of the photovoltaic cell.

[0005] However, in the current scheme, the nanoscale light-trapping structure greatly increases the surface area of ​​single-crystalline silicon in photovoltaic cells, and it is difficult to generate a uniform passivation layer on the nanostructure, resulting in an increase in the recombination rate of non-equilibrium carriers on the surface, thereby reducing the photoelectric conversion efficiency of photovoltaic cells. Summary of the invention

[0006] The present application provides a photovoltaic cell and a photovoltaic module, aiming to improve the conversion efficiency of the photovoltaic cell.

[0007] In a first aspect, an embodiment of the present application provides a photovoltaic cell, the photovoltaic cell comprising:

[0008] Battery body;

[0009] At least one surface of the battery body includes a first region and a second region;

[0010] The first area is configured as a suede structure;

[0011] The second area is configured as a plurality of pits;

[0012] The projection size of the pit on the surface of the battery body is 0.5 to 100 microns;

[0013] The deviation angle between the side wall of the recess and the thickness direction of the battery body is less than 15 degrees.

[0014] Optionally, a projected size of the pit on the surface of the battery body is 1 to 20 microns.

[0015] Optionally, the plurality of pits are distributed in an array on the surface of the battery body;

[0016] The interval between adjacent pits is 2 to 200 micrometers.

[0017] Optionally, a ratio of a projection area of ​​the recess on the surface of the battery body to a surface area of ​​the battery body is 0.4 to 0.85.

[0018] Optionally, the depth of the pit is greater than or equal to 0.1 micrometer.

[0019] Optionally, the pit includes any one or more of a circular hole, a rectangular hole or an irregular shape.

[0020] Optionally, the battery body includes a first electrode;

[0021] Wherein, the first electrode is at least partially arranged on the velvet structure.

[0022] Optionally, the photovoltaic cell further comprises: a passivation layer;

[0023] The passivation layer is disposed on the texture structure and the bottom surface and sidewalls of the pit.

[0024] Optionally, the first electrode includes a first main grid and a first fine grid, the first main grid is arranged on the velvet structure and / or the pit, and the first fine grid is arranged on the velvet structure.

[0025] In a second aspect, an embodiment of the present application provides a method for preparing a photovoltaic cell, the method comprising:

[0026] Preparing a velvet structure on at least one surface of the battery body, wherein the velvet structure is composed of pyramids and / or inverted pyramids distributed along one side of the battery body;

[0027] A plurality of micron-sized pits are prepared on the surface of the battery body.

[0028] Optionally, the step of preparing a suede structure on at least one surface of the battery body comprises:

[0029] The textured structure is prepared on at least one surface of a silicon wafer substrate of the battery body.

[0030] Optionally, the step of preparing a plurality of micron-sized pits on the surface of the battery body comprises:

[0031] A plurality of pits are prepared on the surface of the silicon wafer substrate.

[0032] Optionally, it also includes:

[0033] A passivation layer is prepared on the texture structure and the sidewalls and bottom surfaces of the pits.

[0034] Optionally, it also includes:

[0035] A first electrode is prepared on the textured structure and in the pit, and a second electrode is prepared on the other side of the silicon wafer substrate.

[0036] In a third aspect, an embodiment of the present application provides a method for preparing a double-sided electrode photovoltaic cell, characterized in that the method comprises:

[0037] Preparing a textured structure on at least one surface of a silicon wafer substrate of a battery body;

[0038] A plurality of pits are prepared on the surface of the silicon wafer substrate.

[0039] It also includes: preparing a passivation layer on the suede structure and the sidewalls and bottom surfaces of the pit; or,

[0040] The method also includes: preparing a first electrode on the velvet structure and in the pit, and preparing a second electrode on the other side of the silicon wafer substrate.

[0041] In a fourth aspect, an embodiment of the present application provides a method for preparing a single-sided electrode photovoltaic cell, the method comprising:

[0042] Preparing the velvet structure on at least one surface of the silicon wafer substrate of the battery body;

[0043] A plurality of pits are prepared on the surface of the silicon wafer substrate.

[0044] The method further comprises: preparing a first passivation layer on the suede structure and the sidewalls and bottom surfaces of the pit, and preparing a third functional layer on the first passivation layer;

[0045] Preparing a second passivation layer on the other side of the silicon wafer substrate, and preparing a fourth functional layer on the second passivation layer;

[0046] A third electrode and a fourth electrode are prepared on the other side of the silicon wafer substrate.

[0047] In a fourth aspect, an embodiment of the present invention provides a photovoltaic module, wherein the photovoltaic module includes the photovoltaic cell described above.

[0048] Based on the above photovoltaic cells and photovoltaic modules, the present application has the following beneficial effects:

[0049] In the present application, at least one surface of the cell body of the photovoltaic cell includes a first area and a second area, the first area is set as a velvet structure, and for incident light with a small incident angle, the velvet structure composed of pyramid and / or inverted pyramid structures can reduce the probability of the small-angle incident light being reflected out of the photovoltaic cell, and the second area is set as a plurality of pits with a projected size of 0.5 to 100 microns on the surface of the cell body. The above size is only for example, meaning that the pits studied in the present application are micron-level pits, so as to distinguish them from the nano-level light trapping structure described in the background technology and solve the technical problem thereof; and the deviation angle between the side wall of the pit and the thickness direction of the cell body is less than 15 degrees;

[0050] For incident light with a large incident angle, multiple micron-sized pits on the surface of the photovoltaic cell can reduce the probability of the large-angle incident light being reflected out of the photovoltaic cell. The large-angle incident light is reflected multiple times in the micron-sized pits and has a larger optical path in the photovoltaic cell, thereby improving the photovoltaic cell's absorption effect on the incident light.

[0051] At the same time, compared with the nanoscale light trapping structure, the structural size of the micron-scale pits is larger, and the surface area of ​​the photovoltaic cell with micron-scale pits is smaller. Therefore, a uniform passivation layer can be effectively generated on the surface of the photovoltaic cell, while reducing the recombination rate of non-equilibrium carriers on the surface of the photovoltaic cell, thereby improving the photoelectric conversion efficiency of the photovoltaic cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0053] Figure 1 A schematic diagram of the structure of a photovoltaic cell in an embodiment of the present invention is shown;

[0054] Figure 2 A top view of a photovoltaic cell in an embodiment of the present invention is shown;

[0055] Figure 3 A schematic structural diagram of a double-sided electrode photovoltaic cell in an embodiment of the present invention is shown;

[0056] Figure 4A schematic structural diagram of a single-sided electrode photovoltaic cell in an embodiment of the present invention is shown;

[0057] Figure 5 A flowchart showing a method for preparing a photovoltaic cell in an embodiment of the present invention is shown;

[0058] Figure 6 A flowchart showing a method for preparing a double-sided electrode photovoltaic cell according to an embodiment of the present invention is shown;

[0059] Figure 7 A flowchart showing the steps of a method for preparing a single-sided electrode photovoltaic cell in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] In order to reduce the reflection of incident light on the surface of photovoltaic cells, increase the absorption effect of incident light, and improve power generation, photovoltaic cells are usually designed with a velvet structure with a pyramid structure and an inverted pyramid structure on the surface through a velvet process. The velvet structure has a good anti-reflection effect for vertical incident light or incident light with a small incident angle, which can reduce the probability of the small-angle incident light being reflected out of the photovoltaic cell. However, it is not effective for incident light with a large incident angle, that is, the omnitropy of the photovoltaic cell is not good. Photovoltaic cells with poor omnitropy need to set the best light receiving angle or use a tracking bracket to achieve a larger power generation. The best light receiving angle changes according to the geographical location, time and season, making it difficult to adjust the fixed bracket in real time to make the photovoltaic cell reach the best light receiving angle, and the tracking bracket is usually expensive, so improving the omnitropy of the photovoltaic cell is a relatively simple way to increase power generation.

[0062] The following describes in detail a photovoltaic cell and a photovoltaic module provided by the present invention by listing several specific embodiments.

[0063] See also Figure 1 , shows a schematic diagram of the structure of a photovoltaic cell provided by an embodiment of the present invention, such as Figure 1 As shown, the photovoltaic cell may include: a cell body 10 , at least one surface of the cell body 10 includes a first region 20 and a second region 30 , wherein the first region 20 is provided with a suede structure, and the second region 30 is provided with a plurality of pits 31 .

[0064] Among them, the first area with a velvet structure is composed of pyramids and / or inverted pyramid structures distributed along the surface of the battery body. The battery body can be prepared from a single crystal silicon wafer, and accordingly, the velvet structure is a regular or irregular pyramid and / or inverted pyramid structure prepared on the surface of a single crystal silicon wafer through a velvet making process. The battery body can also be prepared from a polycrystalline silicon wafer, and accordingly, the velvet structure is a regular or irregular pyramid and / or inverted pyramid structure prepared on the surface of a polycrystalline silicon wafer through a velvet making process.

[0065] In the embodiment of the present invention, the surface of the battery body may be the light-receiving surface of the battery body, that is, the surface that is in direct contact with the incident light. At the same time, incident light with an incident angle greater than or equal to 45 degrees may be determined as high-angle incident light, referring to Figure 1 The incident angle of the incident light B is α, and α is greater than 45 degrees, that is, the incident light B is a large-angle incident light. The incident light B is irradiated on the first area 20 with a suede structure on the surface of the photovoltaic cell. Under the reflection effect of the pyramid and / or inverted pyramid structure in the suede structure, the incident light B is emitted in a direction away from the photovoltaic cell after one reflection. Therefore, the incident light B has a very small optical path in the photovoltaic cell, resulting in a poor absorption effect of the photovoltaic cell on the incident light B.

[0066] Furthermore, incident light with an incident angle less than 45 degrees can be determined as small-angle incident light. Figure 1 The incident angle of the incident light C is β, β is less than 45 degrees, that is, the incident light C is a small-angle incident light. The incident light C is irradiated on the first area 20 with a velvet structure on the surface of the photovoltaic cell. Under the reflection effect of the pyramid and / or inverted pyramid structure in the velvet structure, the incident light C can be reflected multiple times in the velvet structure of the photovoltaic cell. Therefore, the incident light C has a larger optical path in the photovoltaic cell, so that the photovoltaic cell has a better absorption effect on the incident light C.

[0067] It can be seen that a photovoltaic cell with only a velvet structure has a good absorption effect for light incident at a small angle, but a poor absorption effect for light incident at a large angle. Therefore, the omnidirectionality of the photovoltaic cell is not good. When a photovoltaic module containing the photovoltaic cell is installed in an aircraft, a car or a building, the installation position is restricted because the photovoltaic cell needs to have an optimal light receiving angle, or a tracking bracket is required to achieve a larger power generation, which is costly.

[0068] In addition, the surface of the cell body of the photovoltaic cell also includes a second area, in which a plurality of pits are arranged, and the projection size of the pits on the surface of the cell body is 0.5 to 100 microns. The above sizes are for example purposes, meaning that the pits studied in this application are micron-level pits, as distinguished from the nanoscale light-trapping structures described in the background technology; at the same time, the deviation angle between the side walls of the pits and the thickness direction of the cell body is less than 15 degrees, so that small-angle incident light can be irradiated into the pits and undergo multiple reflections in the pits.

[0069] Reference Figure 1 The surface of the cell body 10 of the photovoltaic cell further includes a second region 30 provided with a plurality of micron-sized pits 31. Meanwhile, the deviation angle between the sidewall of the pit 31 and the thickness direction of the cell body 10 is 0 degrees.

[0070] The shape of the micron-sized pit 31 can be any one or more of a circular hole, a rectangular hole or an irregular shape. If the shape of the micron-sized pit 31 is a circular hole, the diameter range of the micron-sized pit 31 is 0.5 to 100 microns. If the shape of the micron-sized pit 31 is a rectangular hole or an irregular deep hole, the length of the diagonal of the micron-sized pit 31 is 0.5 to 100 microns.

[0071] Specifically, the incident light A is also a large-angle incident light with an incident angle of α. When the incident light A is irradiated on the micron-sized pits 31 on the surface of the photovoltaic cell, the incident light A can be reflected multiple times in the micron-sized pits 31 of the photovoltaic cell under the reflection effect of the side walls and bottom of the micron-sized pits 31. Therefore, the incident light A has a larger optical path in the photovoltaic cell, and the photovoltaic cell has a better absorption effect on the incident light A.

[0072] It can be seen from this that for the photovoltaic cell with a velvet structure and micron-sized pits in the cell body, the velvet structure has a good absorption effect for small-angle incident light, and the micron-sized pits can improve the photovoltaic cell's absorption effect for small-angle incident light. At the same time, the micron-sized pits have a good absorption effect for large-angle incident light. Therefore, the photovoltaic cell has high omnidirectionality. When the photovoltaic module containing the photovoltaic cell is installed in aircraft, automobiles and buildings, the photovoltaic cell can have a good incident light absorption effect without the need for the installation position and the use of a tracking bracket, thereby improving the photoelectric conversion efficiency of the photovoltaic module and achieving a larger power generation.

[0073] Furthermore, since the projection size of the micron-sized pits on the surface of the battery body is 0.5 to 100 microns, the structural size of the micron-sized pits is larger than that of the nano-sized light-trapping structure, which can avoid the passivation layer from being successfully prepared on the smaller nano-sized light-trapping structure, thereby ensuring that a uniform passivation layer can be effectively generated on the surface of the photovoltaic cell. At the same time, the surface area of ​​the photovoltaic cell with micron-sized pits is smaller, so the specific surface area of ​​the photovoltaic cell can be reduced, thereby reducing the recombination rate of non-equilibrium carriers on the surface of the photovoltaic cell, and will not affect the lateral transmission and collection of carriers on the surface of the photovoltaic cell, ultimately improving the photoelectric conversion efficiency of the photovoltaic cell.

[0074] In an embodiment of the present invention, a photovoltaic cell includes: a cell body; at least one surface of the cell body includes a first region and a second region; the first region is configured as a velvet structure; the second region is configured as a plurality of pits; the projected size of the pits on the surface of the cell body is 0.5 to 100 microns; the deviation angle between the sidewalls of the pits and the thickness direction of the cell body is less than 15 degrees. In the present application, at least one surface of the cell body of the photovoltaic cell includes a first region and a second region, the first region is configured as a velvet structure, and for incident light with a small incident angle, the velvet structure composed of pyramid and / or inverted pyramid structures can reduce the probability of the small-angle incident light being reflected out of the photovoltaic cell, the second region is configured as a plurality of pits with a projected size of 0.5 to 100 microns on the surface of the cell body, and the deviation angle between the sidewalls of the pits and the thickness direction of the cell body is less than 15 degrees, and for incident light with a large incident angle, the plurality of micrometer-level pits on the surface of the photovoltaic cell The pits can reduce the probability of the large-angle incident light being reflected out of the photovoltaic cell. The large-angle incident light is reflected multiple times in the micron-sized pits and has a larger optical path in the photovoltaic cell, thereby improving the photovoltaic cell's absorption effect on the incident light. At the same time, compared with the nanoscale light trapping structure, the micron-sized pits have a larger structural size, and the photovoltaic cell with micron-sized pits has a smaller surface area. Therefore, a uniform passivation layer can be effectively generated on the surface of the photovoltaic cell, while reducing the recombination rate of non-equilibrium carriers on the surface of the photovoltaic cell, thereby improving the photoelectric conversion efficiency of the photovoltaic cell.

[0075] Optionally, the projection size of the pit on the surface of the battery body is 1 to 20 micrometers, thereby ensuring that the size of the pit arranged in the second area of ​​the surface of the battery body is relatively uniform and moderate.

[0076] Optional, see Figure 2 , shows a top view of a photovoltaic cell provided by an embodiment of the present invention, such as Figure 2As shown, a plurality of micrometer-sized pits 31 may be distributed in an array on the surface of the battery body, and adjacent micrometer-sized pits 31 may be spaced 2 to 200 micrometers apart, so that other structures of the photovoltaic cell may be arranged on the velvet structure of the first region 20 between adjacent micrometer-sized pits 31 to realize the functions of the photovoltaic cell.

[0077] Optionally, the pit may include any one or more of a circular hole, a rectangular hole or an irregular shape, so that when the incident light is irradiated on the bottom surface and the side wall of the micron-sized pit, multiple reflections can be performed in the micron-sized pit, referring to Figure 2 , the micron-sized pits 31 are circular holes.

[0078] Optionally, the depth of the pit may be greater than or equal to 0.1 micrometer, and the ratio of the projected area of ​​the micrometer-sized pit on the surface of the battery body to the surface area of ​​the battery body may be 0.4 to 0.85.

[0079] In an embodiment of the present invention, the depth of the micron-scale pits and the ratio can be determined according to the specific application scenario of the photovoltaic module including the photovoltaic cell. Specifically, for application scenarios where large-angle incident light accounts for a relatively large proportion, the projection size of the pits on the surface of the battery body can be increased, or the number of the pits can be increased, so that the ratio of the projection area of ​​the pits on the surface of the battery body to the surface area of ​​the battery body is larger, thereby increasing the absorption effect of the photovoltaic cell for large-angle incident light; for application scenarios where large-angle incident light accounts for a relatively small proportion, the projection size of the pits on the surface of the battery body can be reduced, or the number of the pits can be reduced, so that the ratio of the projection area of ​​the pits on the surface of the battery body to the surface area of ​​the battery body is smaller, so that the photovoltaic cell has a better absorption effect for incident light.

[0080] At the same time, when the incident angle of large-angle incident light is large, the micron-sized pits with a smaller depth can also make the incident light complete multiple reflections in the micron-sized pits, so the depth of the micron-sized pits can be reduced; when the incident angle of large-angle incident light is small, the micron-sized pits with a larger depth can ensure that the incident light completes multiple reflections in the micron-sized pits, so it is necessary to increase the depth of the micron-sized pits.

[0081] Optionally, the battery body may include a first electrode, wherein the first electrode is at least partially disposed on the velvet structure, that is, the first electrode cannot be entirely disposed in micron-sized pits, thereby reducing the filling of the micron-sized pits by the first electrode and avoiding affecting the light trapping function of the micron-sized pits for reflecting light at large angles.

[0082] Optionally, the photovoltaic cell may further include: a passivation layer, wherein the passivation layer is arranged on the bottom and side walls of the velvet structure and the pits. Compared with the nanoscale light trapping structure, the micrometer-scale pits have a larger structural size, and the photovoltaic cell with micrometer-scale pits has a smaller surface area. Therefore, a uniform passivation layer can be effectively generated on the surface of the photovoltaic cell to achieve surface passivation of the photovoltaic cell.

[0083] Optionally, the photovoltaic cell in the embodiment of the present invention may be a photovoltaic cell with double-sided electrodes, such as a Passivated Emitter and Rear Cell (PERC), see Figure 3 , showing a schematic structural diagram of a double-sided electrode photovoltaic cell provided by an embodiment of the present invention, such as Figure 3 As shown, the battery body includes a silicon wafer substrate 11 , a first electrode 13 and a first functional layer 12 arranged on one side of the silicon wafer substrate 11 , and a second functional layer 14 and a second electrode 15 arranged on the other side of the silicon wafer substrate 11 .

[0084] Among them, the first functional layer 12 is arranged on the velvet structure of the first area 20 and on the bottom and side wall of the pit 31 in the second area 30, and the first functional layer 12 has a first hollow structure, and the first electrode 13 is located at the position of the first hollow structure. The second functional layer 14 is arranged on the other side of the silicon wafer substrate 11, and the second functional layer 14 has a second hollow structure, and the second electrode 15 is located at the position of the second hollow structure.

[0085] Specifically, the silicon wafer substrate can be an n-type silicon wafer substrate prepared from an n-type crystalline silicon wafer; the first functional layer can be a multi-layer structure, for example, the first functional layer can include 2 nanometers thick silicon oxide and 70 nanometers thick silicon nitride, which respectively play the role of surface passivation and anti-reflection on one side of the photovoltaic cell; the second functional layer can also be a multi-layer structure, for example, the second functional layer can include 2 nanometers thick silicon oxide, 15 nanometers thick aluminum oxide and 50 nanometers thick silicon nitride, thereby realizing the surface passivation and anti-reflection function on the other side of the photovoltaic cell.

[0086] Furthermore, a first electrode is arranged on one side of a silicon wafer substrate, and a second electrode is arranged on the other side of the silicon wafer substrate, thereby constituting a photovoltaic cell with double-sided electrodes. Specifically, a first hollow structure can be prepared on the first functional layer using a mask, and the first electrode can be located at the position of the first hollow structure, so that the first electrode can be arranged on the velvet structure or in a pit; a second hollow structure can also be prepared on the second functional layer using a mask, and the second electrode can be located at the position of the second hollow structure, so that the second electrode can be arranged on the other side of the silicon wafer substrate.

[0087] Optional, see Figure 3 The first electrode 13 may include a first main gate 131 and a first fine gate 132, wherein the first main gate 131 may be arranged on the velvet structure of the first region 20 and / or in the pit 31 in the second region 30, and the first fine gate 132 may be arranged on the velvet structure.

[0088] Specifically, for photovoltaic cells, the main function of the first fine grid is to collect the current generated by the photovoltaic cells and transmit the current to the first main grid, so that multiple photovoltaic cells can collect the current generated by multiple photovoltaic cells through the first main grid and transmit it to the junction box, thereby providing power to external devices. Since the number of first fine grids is large and their width is small, Figure 2 The first fine grid 132 can be set on the velvet structure between adjacent pits 31, while the number of the first main grid is small and its width is large. Therefore, the first main grid 131 can be set in the pits 31, or on the velvet structure between adjacent pits 31, or in the pits 31 and on the velvet structure at the same time, thereby making the structure of the photovoltaic cell more compact and improving the photoelectric conversion efficiency of the photovoltaic cell.

[0089] Optionally, the photovoltaic cell in the embodiment of the present invention may be a photovoltaic cell with a single-sided electrode, such as a tunneling oxide passivation contact cell (TOPCon), a polysilicon oxide selective passivation contact cell (POLO), an interdigitated back contact cell (IBC), a silicon heterojunction cell (SHJ), see Figure 4 , showing a schematic structural diagram of a single-sided electrode photovoltaic cell provided by an embodiment of the present invention, such as Figure 4 As shown, the battery body includes a silicon wafer substrate 11, a first passivation layer 17 and a third functional layer 18 arranged on one side of the silicon wafer substrate 11, and a second passivation layer 19, a fourth functional layer 110, a third electrode 16 and a fourth electrode 120 arranged on the other side of the silicon wafer substrate 11.

[0090] Among them, the velvet structure of the first region 20 is arranged on one surface of the silicon wafer substrate 11, the bottom surface of the pit 31 is arranged in the silicon wafer substrate, the first passivation layer 17 is arranged on the velvet structure and the bottom surface and side wall of the pit 31, the third functional layer 18 is arranged on the side of the first passivation layer 17 away from the silicon wafer substrate 11, the second passivation layer 19 is arranged on the other side of the silicon wafer substrate 11, the fourth functional layer 110 is arranged on the side of the second passivation layer 19 away from the silicon wafer substrate 11, the fourth functional layer 110 has a third hollow structure, and the third electrode 16 and the fourth electrode 120 are arranged at the position of the third hollow structure.

[0091] Specifically, the silicon wafer substrate can be an n-type silicon wafer substrate prepared from an n-type crystalline silicon wafer; the first passivation layer can be amorphous silicon or silicon oxide, thereby playing the role of surface passivation on one side of the photovoltaic cell; the third functional layer can be a multi-layer structure, for example, a multi-layer silicon nitride structure with a total thickness of 70 nanometers, which plays the role of surface field passivation and anti-reflection on one side of the photovoltaic cell; the second passivation layer can be amorphous silicon or silicon oxide, thereby playing the role of surface passivation on the other side of the photovoltaic cell; the fourth functional layer can play the role of surface field passivation and anti-reflection on one side of the photovoltaic cell.

[0092] Furthermore, a third electrode and a fourth electrode are arranged on the other side of the silicon wafer substrate to form a photovoltaic cell with a single-sided electrode. Specifically, a third hollow structure can be prepared on the fourth functional layer using a mask, and the third electrode and the fourth electrode are arranged at the position of the third hollow structure.

[0093] Optional, see Figure 4 A first collection layer 162 and a first transmission layer 161 are arranged between the third electrode 16 and the second passivation layer 19, the first collection layer 162 is arranged on the side of the second passivation layer 19 away from the silicon wafer substrate 11, and the first transmission layer 161 is arranged on the side of the first collection layer 162 away from the second passivation layer 19; a second collection layer 122 and a second transmission layer 121 are arranged between the fourth electrode 120 and the second passivation layer 19, the second collection layer 122 is arranged on the side of the second passivation layer 19 away from the silicon wafer substrate 11, and the second transmission layer 121 is arranged on the side of the second collection layer 122 away from the second passivation layer 19.

[0094] Specifically, when the silicon wafer substrate adopts n-type crystalline silicon wafer, the first collection layer can be a majority carrier collection area composed of n-type doped amorphous silicon, and the second collection layer can be a minority carrier collection area composed of p-type doped amorphous silicon. The first collection layer and the second collection layer are arranged at intervals on the surface of the second passivation layer on the other side of the silicon wafer substrate. Correspondingly, the first transmission layer is the carrier transmission layer corresponding to the first collection layer, that is, the majority carrier transmission layer, the third electrode is the majority carrier terminal electrode of the photovoltaic cell with a single-sided electrode, the second transmission layer is the carrier transmission layer corresponding to the second collection layer, that is, the minority carrier transmission layer, and the fourth electrode is the minority carrier terminal electrode of the photovoltaic cell with a single-sided electrode.

[0095] The present invention also provides a method for preparing the above photovoltaic cell, see Figure 5 , shows a flow chart of steps of a method for preparing a photovoltaic cell provided by an embodiment of the present invention, the method may include the following steps:

[0096] Step 101 : preparing a suede structure on at least one surface of a battery body, wherein the suede structure is composed of pyramids and / or inverted pyramids distributed along one side of the battery body.

[0097] In this step, a velvet structure consisting of a pyramid and / or an inverted pyramid structure may be prepared on the battery body through a velvet process.

[0098] Specifically, the velvet structure is composed of pyramids and / or inverted pyramid structures continuously distributed along one side of the battery body. The battery body can be prepared from a single crystal silicon wafer, and accordingly, the velvet structure is a regular pyramid and / or inverted pyramid structure prepared on one side of the single crystal silicon wafer through a velvet making process. The battery body can also be prepared from a polycrystalline silicon wafer, and accordingly, the velvet structure is an irregular pyramid and / or inverted pyramid structure prepared on one side of the polycrystalline silicon wafer through a velvet making process.

[0099] Step 102: Prepare a plurality of micron-sized pits on the surface of the battery body.

[0100] In this step, a corresponding hole structure can be formed by coating a photoresist on the surface of the battery body with a velvet structure prepared in the above step, and then irradiating it with light using a mask with a corresponding pattern and then washing away the photoresist at unblocked positions. A deep reaction particle etching process is further used to etch a plurality of pits at the above hole positions, and the projection size of the pits on the surface of the battery body is 0.5 to 100 microns, and the deviation angle between the side walls of the pits and the thickness direction of the battery body is less than 15 degrees.

[0101] See also Figure 6 , shows a flowchart of a method for preparing a double-sided electrode photovoltaic cell provided by an embodiment of the present invention, the method may include the following steps:

[0102] Step 201: Prepare the textured structure on at least one surface of the silicon wafer substrate of the battery body.

[0103] In this step, the silicon wafer substrate can be an n-type silicon wafer substrate prepared from an n-type crystalline silicon wafer. The thickness of the silicon wafer substrate can be 150 microns, or it can be an ultra-thin crystalline silicon wafer with a thickness of 10 to 50 microns, or a medium crystalline silicon wafer with a thickness of 50 to 100 microns. The silicon wafer substrate can be single crystal or polycrystalline.

[0104] Furthermore, a textured surface structure composed of pyramids and / or inverted pyramids can be prepared on at least one surface of the silicon wafer substrate through a texture making process.

[0105] Step 202: Prepare a plurality of pits on the surface of the silicon wafer substrate.

[0106] In this step, a corresponding hole structure can be formed by coating a photoresist on the surface of the silicon wafer substrate with a velvet structure prepared in the above step, and then irradiating it with light using a mask with a corresponding pattern and then washing away the photoresist at unblocked positions. A deep reaction particle etching process is further used to etch a plurality of pits at the above hole positions, and the projection size of the pits on the surface of the battery body is 0.5 to 100 microns, and the deviation angle between the side walls of the pits and the thickness direction of the battery body is less than 15 degrees.

[0107] Specifically, the pits may be a circular hole structure, the average pore diameter may be 5 micrometers, the spacing between adjacent pits may be 15 micrometers, and the depth may be 0.5 micrometers.

[0108] Furthermore, after a plurality of pits are prepared on one side of the silicon wafer substrate with a textured structure, a layered PN junction structure layer can be prepared by diffusion on the surface of the textured structure and the sidewalls and bottom of the pits to achieve the ability to separate carriers.

[0109] Step 203: prepare a passivation layer on the textured structure and the sidewalls and bottom surfaces of the pits.

[0110] In this step, a passivation layer may be deposited on the sidewalls and bottom surfaces of the textured structure and the pits. For example, the passivation layer may include 2 nanometers of silicon oxide to perform a surface passivation function on one side of the photovoltaic cell.

[0111] Furthermore, 70 nanometers thick silicon nitride can be prepared on the passivation layer to play the role of anti-reflection on one side of the photovoltaic cell, and 2 nanometers thick silicon oxide and 70 nanometers thick silicon nitride form a first functional layer with a multilayer structure.

[0112] Step 204: prepare a first electrode on the textured structure and in the pit, and prepare a second electrode on the other side of the silicon wafer substrate.

[0113] In this step, a first electrode may be prepared on the textured structure and in the pits.

[0114] Specifically, a first hollow structure may be prepared on the first functional layer using a mask, and the first electrode may be located at the position of the first hollow structure, so that the first electrode may be disposed on the velvet structure or in the pit.

[0115] Furthermore, a second functional layer can be deposited on the other side of the silicon wafer substrate. The second functional layer can be a multi-layer structure. For example, the second functional layer can include 2 nanometers thick silicon oxide, 15 nanometers thick aluminum oxide and 50 nanometers thick silicon nitride, thereby realizing the surface passivation and anti-reflection function of the other side of the photovoltaic cell.

[0116] Furthermore, a second electrode is prepared on the other side of the silicon wafer substrate. Specifically, a second hollow structure can be prepared on the second functional layer using a mask, and the second electrode is located at the position of the second hollow structure, so that the second electrode can be set on the other side of the silicon wafer substrate.

[0117] Optional, see Figure 7 , shows a flowchart of a method for preparing a single-sided electrode photovoltaic cell provided by an embodiment of the present invention, the method may include the following steps:

[0118] Step 301: Prepare the textured structure on at least one surface of the silicon wafer substrate of the battery body.

[0119] In this step, the silicon wafer substrate may be an n-type silicon wafer substrate prepared from an n-type crystalline silicon wafer, and the thickness of the silicon wafer substrate may be 100 microns.

[0120] Furthermore, a textured surface structure composed of continuously distributed pyramids and / or inverted pyramid structures can be prepared by a textured process on at least one surface of the silicon wafer substrate.

[0121] Step 302: Prepare a plurality of pits on the surface of the silicon wafer substrate.

[0122] In this step, deep holes with a certain depth can be formed on one side of the silicon wafer substrate with a velvet structure prepared in the above step by laser ablation process. After the laser ablation process, the deep holes can be chemically polished to obtain smooth side walls and bottom surfaces, thereby preparing a plurality of pits, and the projection size of the pits on the surface of the battery body is 0.5 to 100 microns, and the deviation angle between the side walls of the pits and the thickness direction of the battery body is less than 15 degrees.

[0123] Specifically, the pits may be a circular hole structure, the average pore diameter may be 2 micrometers, the spacing between adjacent pits may be 5 micrometers, and the depth may be 1 micrometer.

[0124] Step 303: prepare a first passivation layer on the suede structure and the sidewalls and bottom surfaces of the pit, and prepare a third functional layer on the first passivation layer.

[0125] In this step, a first passivation layer may be prepared on the sidewalls and bottom surfaces of the textured structure and the pits. The first passivation layer may be amorphous silicon or silicon oxide, thereby performing the surface passivation function on one side of the photovoltaic cell.

[0126] Furthermore, a third functional layer can be prepared on the first passivation layer. The third functional layer can be a multilayer structure, for example, a multilayer silicon nitride structure with a total thickness of 70 nanometers, which plays the role of surface field passivation and anti-reflection on one side of the photovoltaic cell.

[0127] Step 304: prepare a second passivation layer on the other side of the silicon wafer substrate, and prepare a fourth functional layer on the second passivation layer.

[0128] In this step, a second passivation layer may be prepared on the other side of the silicon wafer substrate. The second passivation layer may also be amorphous silicon or silicon oxide, thereby playing the role of surface passivation on the other side of the photovoltaic cell.

[0129] Furthermore, a fourth functional layer may be prepared on the second passivation layer, and the fourth functional layer may play the role of surface field passivation and anti-reflection on one side of the photovoltaic cell.

[0130] Step 305: Prepare a third electrode and a fourth electrode on the other surface of the silicon wafer substrate.

[0131] In this step, a third electrode and a fourth electrode can be arranged on the other side of the silicon wafer substrate to form a photovoltaic cell with a single-sided electrode. Specifically, a third hollow structure can be prepared on the fourth functional layer using a mask, and the third electrode and the fourth electrode can be arranged at the position of the third hollow structure.

[0132] In an embodiment of the present invention, a first collection layer and a first transmission layer may be arranged between the third electrode and the second passivation layer, the first collection layer being arranged on a side of the second passivation layer away from the silicon wafer substrate, and the first transmission layer being arranged on a side of the first collection layer away from the second passivation layer; a second collection layer and a second transmission layer are arranged between the fourth electrode and the second passivation layer, the second collection layer being arranged on a side of the second passivation layer away from the silicon wafer substrate, and the second transmission layer being arranged on a side of the second collection layer away from the second passivation layer.

[0133] Specifically, when the silicon wafer substrate adopts n-type crystalline silicon wafer, the first collection layer can be a majority carrier collection area composed of n-type doped amorphous silicon, and the second collection layer can be a minority carrier collection area composed of p-type doped amorphous silicon. The first collection layer and the second collection layer are arranged at intervals on the surface of the second passivation layer on the other side of the silicon wafer substrate. The ratio of the projected area of ​​the first collection layer and the second collection layer on the second passivation layer can be 5% to 45%, and an electrical isolation gap is arranged between the first collection layer and the second collection layer. Correspondingly, the first transmission layer is a carrier transmission layer corresponding to the first collection layer, that is, a majority carrier transmission layer, the third electrode is a majority carrier terminal electrode of a photovoltaic cell with a single-sided electrode, the second transmission layer is a carrier transmission layer corresponding to the second collection layer, that is, a minority carrier transmission layer, and the fourth electrode is a minority carrier terminal electrode of a photovoltaic cell with a single-sided electrode. In addition, the first collection layer and the second collection layer can also be made of doped polycrystalline silicon material.

[0134] It should be noted that, for the method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the embodiments of the present application are not limited by the described order of actions, because according to the embodiments of the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present application.

[0135] In addition, the present invention also provides a photovoltaic module, which is composed of the above-mentioned photovoltaic cell.

[0136] 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.

[0137] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A photovoltaic cell, characterized in that: The photovoltaic cell comprises: Battery body; At least one surface of the battery body includes a first area and a second area; the first area and the second area have no overlapping area; The first area is configured as a velvet structure; the velvet structure includes a pyramid and / or an inverted pyramid structure; The second area is configured as a plurality of mutually independent pits.

2. The photovoltaic cell according to claim 1, characterized in that: The interval between adjacent pits is 2 to 200 microns; or the projection size of the pits on the surface of the battery body is 0.5 to 100 microns; or the deviation angle between the side wall of the pit and the thickness direction of the battery body is less than 15 degrees; or the projection size of the pit on the surface of the battery body is 1 to 20 microns.

3. The photovoltaic cell according to claim 1, characterized in that: A ratio of a projected area of ​​the recess on the surface of the battery body to a surface area of ​​the battery body is 0.4 to 0.

85.

4. The photovoltaic cell according to any one of claims 1 to 3, characterized in that: The depth of the pit is greater than or equal to 0.1 micrometer.

5. The photovoltaic cell according to any one of claims 1 to 4, characterized in that: The pits include any one or more of a circular hole, a rectangular hole or an irregular shape.

6. The photovoltaic cell according to any one of claims 1 to 4, characterized in that: The battery body includes a first electrode; Wherein, the first electrode is at least partially arranged on the velvet structure.

7. The photovoltaic cell according to claim 1, characterized in that: The photovoltaic cell further comprises: a passivation layer; The passivation layer is disposed on the texture structure and the bottom surface and sidewalls of the pit.

8. The photovoltaic cell according to claim 6, characterized in that: The first electrode includes a first main grid and a first fine grid, the first main grid is arranged on the velvet structure and / or the pit, and the first fine grid is arranged on the velvet structure.

9. A method for preparing a photovoltaic cell, characterized in that: The method comprises: Preparing a velvet structure on at least one surface of the battery body, wherein the velvet structure is composed of pyramids and / or inverted pyramids distributed along one side of the battery body; A plurality of micron-sized pits are prepared on the surface of the battery body.

10. The method according to claim 9, characterized in that The step of preparing a suede structure on at least one surface of a battery body comprises: Preparing the velvet structure on at least one surface of the silicon wafer substrate of the battery body; Alternatively, the step of preparing a plurality of micron-sized pits on the surface of the battery body comprises: preparing a plurality of pits on the surface of the silicon wafer substrate.

11. A method for preparing a double-sided electrode photovoltaic cell, characterized in that: The method comprises: Preparing a textured structure on at least one surface of a silicon wafer substrate of a battery body; A plurality of pits are prepared on the surface of the silicon wafer substrate.

12. The method according to claim 11, characterized in that Also includes: Preparing a passivation layer on the suede structure and the sidewalls and bottom surfaces of the pit; or, The method also includes: preparing a first electrode on the velvet structure and in the pit, and preparing a second electrode on the other side of the silicon wafer substrate.

13. A method for preparing a single-sided electrode photovoltaic cell, characterized in that: The method comprises: Preparing a textured structure on at least one surface of a silicon wafer substrate of a battery body; A plurality of pits are prepared on the surface of the silicon wafer substrate.

14. The method according to claim 13, characterized in that Also includes: Preparing a first passivation layer on the suede structure and the sidewalls and bottom surfaces of the pit, and preparing a third functional layer on the first passivation layer; Preparing a second passivation layer on the other side of the silicon wafer substrate, and preparing a fourth functional layer on the second passivation layer; A third electrode and a fourth electrode are prepared on the other side of the silicon wafer substrate.

15. A photovoltaic module, characterized in that: The photovoltaic module comprises the photovoltaic cell according to any one of claims 1 to 8.

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