IBC solar cell and photovoltaic module

Abstract

The utility model discloses an IBC solar cell and a photovoltaic assembly, the IBC solar cell comprises a silicon wafer, a P-type doped region and an N-type doped region, the P-type doped region and the N-type doped region are arranged on the back surface of the silicon wafer and are distributed at intervals in an interdigital manner, the back surface of the silicon wafer further comprises a first dielectric layer, a first electrode and a second electrode, and the first dielectric layer covers the P-type doped region and the N-type doped region. The first dielectric layer is provided with a first opening penetrating to the surface of the P-type doped region and a second opening penetrating to the N-type doped region, the first opening and the second opening are distributed at intervals in an interdigital mode, the first electrode comprises a first bottoming electrode and a first covering electrode, and the second electrode comprises a second bottoming electrode and a second covering electrode. The first electrode comprises a first bottoming electrode and a second covering electrode, the first bottoming electrode is filled in the first opening and is in ohmic contact with the P-type doped region, the second electrode comprises a second bottoming electrode and a second covering electrode, and the second bottoming electrode is filled in the second opening and is in ohmic contact with the N-type doped region. The IBC solar cell provided by the utility model can greatly reduce the silver consumption of the electrode and reduce the metallization cost.

Description

Technical Field

[0001] The utility model belongs to the technical field of solar cells, and specifically relates to an IBC solar cell and a photovoltaic module. Background Art

[0002] Interdigitated Back Contact solar cells, referred to as IBC cells, are a type of back contact solar cells. The characteristic of IBC solar cells is that the emitter electrode and base electrode of the cell are both made on the back of the cell, thereby reducing the shading of the front of the cell, improving the utilization rate of the incident light on the front, and thus improving the electrical performance of the cell.

[0003] Electrode metallization is one of the important processes of crystalline silicon solar cells. It is an important component of the manufacturing cost of the cell and a key factor affecting the photovoltaic performance of the cell. At present, IBC solar cells usually use screen printing silver paste to prepare electrodes. The silver paste consumption is significantly increased compared with PERC cells, and the metallization cost is high. In addition, due to the limitations of silver reserves and prices, the cost reduction space of existing metallization technology is limited, which is one of the key factors restricting the acceleration of IBC solar cell industrialization. The metallization technology that uses base metal copper to replace silver is considered to be an ideal alternative technology for the future metallization of crystalline silicon cells.

[0004] In order to reduce the cost of metallization, there is also a solution of electroplating copper in the prior art. For example, the metal electrodes of Ni seed layer, Cu conductive layer and Ag capping layer can be prepared by electroplating in the laser grooved P area and N area, but this process requires multiple electroplating steps, the process cost is high, and a lot of wastewater is generated, which faces environmental challenges.

[0005] At present, the metallization of N-type batteries in the industry is still mainly based on the preparation of silver electrodes by screen-printed silver paste. For N-type HJT batteries, screen-printed silver-coated copper paste technology has been used first, which can reduce the silver content in the electrode by 50% to 70%. Since IBC solar cells are a type of solar cell that needs to be sintered at high temperature to form an ohmic contact, if the silver-coated copper paste is directly applied to IBC cells, during the high-temperature sintering process, the silver shell will fall off, and the copper ions will migrate to the silicon substrate of the battery, seriously reducing the performance and reliability of the battery. Therefore, the silver-coated copper paste cannot be directly applied to IBC batteries.

[0006] Therefore, in view of the above technical problems, it is necessary to provide an IBC solar cell and photovoltaic module. Utility Model Content

[0007] The utility model aims to provide an IBC solar cell and a photovoltaic module, which can reduce silver consumption and improve the reliability of the battery by optimizing the electrode structure.

[0008] In order to achieve the above purpose, the technical solution provided by an embodiment of the present utility model is as follows:

[0009] An IBC solar cell, the IBC solar cell comprising a silicon wafer and a P-type doping region and an N-type doping region located on the back of the silicon wafer and distributed in an interdigitated manner, the back of the silicon wafer further comprising a first dielectric layer covering the P-type doping region and the N-type doping region, and a first electrode and a second electrode, the first dielectric layer is provided with a first opening penetrating to the surface of the P-type doping region and a second opening penetrating to the N-type doping region, the first opening and the second opening are distributed in an interdigitated manner, wherein:

[0010] The first electrode includes a first bottom electrode and a first covering electrode, the first bottom electrode fills the first opening and is in ohmic contact with the P-type doping region, and the second electrode includes a second bottom electrode and a second covering electrode, the second bottom electrode fills the second opening and is in ohmic contact with the N-type doping region.

[0011] In one embodiment, the first bottom electrode fills the first opening and covers a portion of the surface of the first dielectric layer, and the width of the first covering electrode is smaller than the width of the first bottom electrode; and / or,

[0012] The second bottom electrode fills the second opening and covers a portion of the surface of the first dielectric layer. The width of the second covering electrode is smaller than the width of the second bottom electrode.

[0013] In one embodiment, the first dielectric layer comprises AlO X Layer, SiN X Layer, SiO X N Y Layer, SiO X The thickness of the first dielectric layer is 60 nm to 100 nm.

[0014] In one embodiment, the width of the first opening is 1 μm to 40 μm or 40 μm to 400 μm; and / or,

[0015] The second opening has a width of 1 μm to 40 μm or 40 μm to 400 μm.

[0016] In one embodiment, the thickness of the first bottom electrode is 0.1 μm to 1 μm; and / or,

[0017] The thickness of the first covering electrode is 2 μm to 20 μm; and / or,

[0018] The thickness of the second bottom electrode is 0.1 μm to 1 μm; and / or,

[0019] The second covering electrode has a thickness of 2 μm to 20 μm.

[0020] In one embodiment, the width of the first bottom electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or,

[0021] The width of the first covering electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or,

[0022] The width of the second bottom electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or,

[0023] The second covering electrode has a width of 5 μm to 50 μm or 50 μm to 500 μm.

[0024] In one embodiment, the first bottoming electrode is a base metal electrode, the base metal is any one or more of nickel and titanium, and the first covering electrode is a silver-coated copper paste electrode; and / or,

[0025] The second bottoming electrode is a base metal electrode, the base metal is any one or more of nickel and titanium, and the second covering electrode is a silver-coated copper slurry electrode.

[0026] In one embodiment, the P-type doping region and / or the N-type doping region is located inside the back side of the silicon wafer; or,

[0027] The P-type doping region and / or the N-type doping region are located in a doped polysilicon layer on the back of the silicon wafer, and a tunneling layer is provided between the P-type doping region and the back of the silicon wafer and / or between the N-type doping region and the back of the silicon wafer.

[0028] In one embodiment, the front side of the silicon wafer is a pyramid velvet structure, and the back side of the silicon wafer is a polished surface; and / or,

[0029] The front side of the silicon wafer is covered with a second dielectric layer, the second dielectric layer comprising AlO X Layer, SiN X Layer, SiO X N Y Layer, SiO X The thickness of the second dielectric layer is 60 nm to 100 nm.

[0030] The technical solution provided by an embodiment of the present utility model is as follows:

[0031] A photovoltaic assembly comprises a plurality of the above-mentioned IBC solar cells.

[0032] Compared with the prior art, the utility model has the following beneficial effects:

[0033] The electrodes in the IBC solar cell of the utility model include a bottom electrode and a covering electrode. The bottom electrode is an ohmic contact electrode, and the covering electrode is a transmission electrode. The bottom electrode can be made of base metal material, and the covering electrode can be made of silver-clad copper material. By optimizing the electrode structure and materials, the silver consumption of the electrode can be greatly reduced, and the metallization cost can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the utility model, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 This is a schematic diagram of the structure of an IBC solar cell in the first embodiment of the utility model;

[0036] Figure 2 This is a schematic diagram of the structure of the first electrode in the first embodiment of the utility model;

[0037] Figure 3 This is a schematic diagram of the structure of an IBC solar cell in the second embodiment of the utility model;

[0038] Figure 4 This is a schematic diagram of the structure of an IBC solar cell in the third embodiment of the utility model;

[0039] Figure 5 Schematic diagram of the structure of the first electrode in the fourth embodiment of the present utility model. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0041] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0042] The utility model discloses an IBC solar cell, comprising a silicon wafer and a P-type doping region and an N-type doping region which are located on the back of the silicon wafer and are distributed in a forked-finger-like interval. The back of the silicon wafer also comprises a first dielectric layer and a first electrode and a second electrode which are covered on the P-type doping region and the N-type doping region. The first dielectric layer is provided with a first opening which penetrates the surface of the P-type doping region and a second opening which penetrates the N-type doping region. The first opening and the second opening are distributed in a forked-finger-like interval. The first electrode comprises a first bottom electrode and a first covering electrode. The first bottom electrode is filled in the first opening and is in ohmic contact with the P-type doping region. The second electrode comprises a second bottom electrode and a second covering electrode. The second bottom electrode is filled in the second opening and is in ohmic contact with the N-type doping region.

[0043] The first bottoming electrode and the second bottoming electrode are base metal electrodes, the base metal is any one or more of nickel, titanium, etc., and the first covering electrode and the second covering electrode are silver-coated copper paste electrodes.

[0044] The present invention is further described below in conjunction with specific embodiments.

[0045] Ginseng Figure 1 The figure shows a schematic diagram of the structure of an IBC solar cell in the first embodiment of the utility model, including a silicon wafer 10 and a P-type doping region 101 and an N-type doping region 102 located on the back side of the silicon wafer and distributed in a forked-finger pattern. For example, the P-type doping region 101 and the N-type doping region 102 can be formed on the back side of the silicon wafer by boron diffusion and phosphorus diffusion processes, respectively. The structure of the P-type doping region 101 and the N-type doping region 102 distributed in a forked-finger pattern belongs to the existing structure of the IBC solar cell and will not be described in detail here.

[0046] The back side of the silicon wafer in this embodiment further includes a first dielectric layer 11 and a first electrode 12 and a second electrode 13 covering the P-type doping region and the N-type doping region. The first dielectric layer 11 is provided with a first opening (unnumbered) penetrating to the surface of the P-type doping region and a second opening (unnumbered) penetrating to the N-type doping region. The first opening and the second opening are distributed in an interdigitated manner.

[0047] Specifically, the first dielectric layer 11 includes AlOX Layer, SiN X Layer, SiO X N Y Layer, SiO X The thickness of the first dielectric layer is 60 nm to 100 nm. For example, the first dielectric layer 11 in this embodiment is SiO X Layer with a thickness of 60nm to 80nm.

[0048] Among them, the width of the first opening and the second opening is 1μm~40μm or 40μm~400μm. Specifically, the width of the first opening and the second opening corresponding to the fine grid line is 1μm~40μm, and the width of the first opening and the second opening corresponding to the main grid line or welding pad point is 40μm~400μm.

[0049] Ginseng Figure 2 The first electrode 12 is a schematic structural diagram, which includes a first bottom electrode 121 and a first cover electrode 122. The first bottom electrode 121 fills the first opening and is in ohmic contact with the P-type doping region 101. The first cover electrode layer 122 is stacked on the surface of the first bottom electrode 121. Figure 1 As shown, the first bottom electrode 121 fills the first opening and covers a portion of the surface of the first dielectric layer 11 , and the width of the first covering electrode 122 is smaller than the width of the first bottom electrode 121 .

[0050] Exemplarily, in this embodiment, the thickness of the first bottom electrode 121 is 0.1μm to 1μm, and for the fine gate lines and the main gate lines, the widths of the first bottom electrode 121 are 5μm to 50μm and 50μm to 500μm, respectively; the thickness of the first covering electrode 122 is 2μm to 20μm, and for the fine gate lines and the main gate lines, the widths of the first covering electrode 122 are 5μm to 50μm and 50μm to 500μm, respectively.

[0051] Furthermore, the first bottom electrode 121 is a base metal electrode, and the base metal is any one or more of nickel and titanium. For example, the first bottom electrode in the present embodiment is a nickel electrode, which is prepared by an electroplating (light-induced electroplating or electric field-induced electroplating) process or a chemical plating process; the first covering electrode 122 is a silver-coated copper slurry electrode, which is formed by printing silver-coated copper slurry and curing it.

[0052] In the present embodiment, the first covering electrode 122 is prepared on the first bottoming electrode 121 by a printing process. The width of the first covering electrode 122 is smaller than that of the first bottoming electrode 121, which can ensure the positioning accuracy during the printing process and avoid printing deviation of the first covering electrode 122, thereby ensuring the conduction performance of carriers between the first covering electrode 122 and the first bottoming electrode 121 and improving battery efficiency.

[0053] The first electrode in this embodiment is a composite electrode composed of a first bottom electrode 121 and a first covering electrode 122. The first bottom electrode 121 is an ohmic contact electrode with the P-type doping region 101, and the first covering electrode 122 is a transmission electrode for collecting and conducting carriers. The structure and material of the electrode are specifically designed according to its function, which can ensure that the entire electrode is in ohmic contact with the P-type doping region 101 and has good current collection and conduction capabilities. At the same time, it can greatly reduce silver consumption and reduce metallization costs.

[0054] The structure of the second electrode 13 in this embodiment is completely the same as that of the first electrode 12 , and will not be described again here.

[0055] Furthermore, in this embodiment, the front side of the silicon wafer is a pyramid velvet structure, the back side of the silicon wafer is a polished surface, and the front side of the silicon wafer is also covered with a second dielectric layer 14, which includes AlO X Layer, SiN X Layer, SiO X N Y Layer, SiO X The thickness of one or more combinations of layers is 60 nm to 100 nm.

[0056] Ginseng Figure 3 The figure shows a schematic diagram of the structure of an IBC solar cell in the second embodiment of the utility model, including a silicon wafer 10, the back side of the silicon wafer 10 includes a first region and a second region distributed in a forked-finger shape, wherein the silicon wafer 10 is an N-type silicon wafer, a P-type doped region 101 is formed on the first region by a boron diffusion process, and a tunneling layer 15 and an N-doped polysilicon layer 16 are sequentially stacked on the second region, and the N-doped polysilicon layer 16 is the N-type doped region.

[0057] Exemplarily, the tunneling layer 11 is a SiO2 layer with a thickness of 1nm to 3nm; the N-doped polysilicon layer 16 is a phosphorus-doped polysilicon layer with a thickness of 10nm to 150nm, preferably 10nm to 100nm, a square resistance of 20Ω / □ to 200Ω / □, and a phosphorus doping concentration of 1E20 atoms / cm 3 ~1E21 atoms / cm 3 .

[0058] Accordingly, the first dielectric layer 11 in this embodiment is stacked on the N-doped polysilicon layer 16 and the first region on the back side of the silicon wafer, and the first dielectric layer 11 is provided with a first opening penetrating through the surface of the P-type doped region 101 and a second opening penetrating through the N-doped polysilicon layer 16, and the first electrode 12 and the second electrode 13 penetrate through the first opening and the second opening respectively, and form ohmic contacts with the P-type doped region 101 and the N-doped polysilicon layer 16 below respectively. The structures and materials of the first electrode 12 and the second electrode 13 in this embodiment are exactly the same as those in the first embodiment, and are not described in detail here.

[0059] Ginseng Figure 4 The figure shows a schematic diagram of the structure of an IBC solar cell in the third embodiment of the utility model, including a silicon wafer 10, wherein the back side of the silicon wafer 10 includes a first region and a second region distributed in a forked-finger shape, wherein the silicon wafer 10 is an N-type silicon wafer, a tunneling layer 15 and a P-doped polysilicon layer 161 are sequentially stacked on the first region, and a tunneling layer 15 and an N-doped polysilicon layer 162 are sequentially stacked on the second region, and the P-doped polysilicon layer 161 and the N-doped polysilicon layer 162 are P-type doped regions and N-type doped regions.

[0060] Exemplarily, the tunneling layer 11 is a SiO2 layer with a thickness of 1nm to 3nm; the P-doped polysilicon layer 161 and the N-doped polysilicon layer 162 are respectively a boron-doped polysilicon layer and a phosphorus-doped polysilicon layer, with a thickness of 10nm to 150nm, preferably 10nm to 100nm, a square resistance of 20Ω / □ to 200Ω / □, and a boron / phosphorus doping concentration of 1E20 atoms / cm 3 ~1E21 atoms / cm 3 .

[0061] Accordingly, the first dielectric layer 11 in this embodiment is stacked on the P-doped polysilicon layer 161, the N-doped polysilicon layer 162 and the back side of the silicon wafer, and the first dielectric layer 11 is provided with a first opening penetrating the surface of the P-doped polysilicon layer 161 and a second opening penetrating the N-doped polysilicon layer 162. The first electrode 12 and the second electrode 13 penetrate the first opening and the second opening respectively, and form ohmic contacts with the underlying P-doped polysilicon layer 161 and the N-doped polysilicon layer 162 respectively. The structures and materials of the first electrode 12 and the second electrode 13 in this embodiment are exactly the same as those in the first embodiment, and are not described in detail here.

[0062] Ginseng Figure 5 The figure is a schematic diagram of the structure of the first electrode in the fourth embodiment of the utility model. The structure of the IBC solar cell in this embodiment is basically the same as that in the first embodiment. The difference is that in the first electrode of this embodiment, the width of the first covering electrode 122 is equal to the width of the first bottom electrode 121, and the first covering electrode 122 is covered on the entire surface of the first bottom electrode 121 by a printing process.

[0063] Likewise, the structure of the second electrode is the same as that of the first electrode, and will not be described again herein.

[0064] It should be understood that in the above-mentioned first embodiment and the third embodiment, the width of the first covering electrode is less than or equal to the width of the first bottom electrode, and in other embodiments, the width of the first covering electrode may also be greater than the width of the first bottom electrode. In this way, after printing, the first covering electrode not only covers the surface of the first bottom electrode, but also covers part of the surface of the dielectric layer, which will not be elaborated here.

[0065] In addition, only one of the first electrode and the second electrode may adopt the composite structure of the bottom electrode and the cover electrode, which will not be described one by one here.

[0066] It can be seen from the above technical solution that the utility model has the following beneficial effects:

[0067] The electrodes in the IBC solar cell of the utility model include a bottom electrode and a covering electrode. The bottom electrode is an ohmic contact electrode, and the covering electrode is a transmission electrode. The bottom electrode can be made of base metal material, and the covering electrode can be made of silver-clad copper material. By optimizing the electrode structure and materials, the silver consumption of the electrode can be greatly reduced, and the metallization cost can be reduced.

[0068] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0069] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An IBC solar cell, characterized in that: The IBC solar cell comprises a silicon wafer and a P-type doping region and an N-type doping region located on the back of the silicon wafer and distributed in a forked-finger pattern. The back of the silicon wafer further comprises a first dielectric layer covering the P-type doping region and the N-type doping region, and a first electrode and a second electrode. The first dielectric layer is provided with a first opening penetrating through the surface of the P-type doping region and a second opening penetrating through the N-type doping region. The first opening and the second opening are distributed in a forked-finger pattern. The first electrode includes a first bottom electrode and a first covering electrode, the first bottom electrode fills the first opening and is in ohmic contact with the P-type doping region, and the second electrode includes a second bottom electrode and a second covering electrode, the second bottom electrode fills the second opening and is in ohmic contact with the N-type doping region.

2. The IBC solar cell according to claim 1, characterized in that: The first bottom electrode fills the first opening and covers a portion of the surface of the first dielectric layer, and the width of the first covering electrode is smaller than the width of the first bottom electrode; and / or, The second bottom electrode fills the second opening and covers a portion of the surface of the first dielectric layer. The width of the second covering electrode is smaller than the width of the second bottom electrode.

3. The IBC solar cell according to claim 1, characterized in that: The first dielectric layer includes AlO X Layer, SiN X Layer, SiO X N Y Layer, SiO X The thickness of the first dielectric layer is 60 nm to 100 nm.

4. The IBC solar cell according to claim 2, characterized in that: The width of the first opening is 1 μm to 40 μm or 40 μm to 400 μm; and / or, The second opening has a width of 1 μm to 40 μm or 40 μm to 400 μm.

5. The IBC solar cell according to claim 2, characterized in that: The thickness of the first bottom electrode is 0.1 μm to 1 μm; and / or, The thickness of the first covering electrode is 2 μm to 20 μm; and / or, The thickness of the second bottom electrode is 0.1 μm to 1 μm; and / or, The second covering electrode has a thickness of 2 μm to 20 μm.

6. The IBC solar cell according to claim 2, characterized in that: The width of the first bottom electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or, The width of the first covering electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or, The width of the second bottom electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or, The second covering electrode has a width of 5 μm to 50 μm or 50 μm to 500 μm.

7. The IBC solar cell according to claim 1, characterized in that: The first bottoming electrode is a base metal electrode, the base metal is any one or more of nickel and titanium, and the first covering electrode is a silver-coated copper paste electrode; and / or, The second bottoming electrode is a base metal electrode, the base metal is any one or more of nickel and titanium, and the second covering electrode is a silver-coated copper slurry electrode.

8. The IBC solar cell according to claim 1, characterized in that: The P-type doping region and / or the N-type doping region are located inside the back side of the silicon wafer; or, The P-type doping region and / or the N-type doping region are located in a doped polysilicon layer on the back of the silicon wafer, and a tunneling layer is provided between the P-type doping region and the back of the silicon wafer and / or between the N-type doping region and the back of the silicon wafer.

9. The IBC solar cell according to claim 1, characterized in that: The front side of the silicon wafer is a pyramid velvet structure, and the back side of the silicon wafer is a polished surface; and / or, The front side of the silicon wafer is covered with a second dielectric layer, the second dielectric layer comprising AlO X Layer, SiN X Layer, SiO X N Y Layer, SiO X The thickness of the second dielectric layer is 60 nm to 100 nm.

10. A photovoltaic module, characterized in that: The photovoltaic module comprises several IBC solar cells according to any one of claims 1 to 9.

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