TOPCon solar cell and photovoltaic module

Abstract

The TOPCon solar cell comprises a silicon substrate, a tunneling layer, a doped polycrystalline silicon layer, a first dielectric layer and a first electrode, the tunneling layer, the doped polycrystalline silicon layer, the first dielectric layer and the first electrode are sequentially stacked on the back face of the silicon substrate, and the first dielectric layer is provided with a first opening penetrating to the surface of the doped polycrystalline silicon layer. The first electrode comprises a first bottoming electrode and a first covering electrode, the first opening is filled with the first bottoming electrode, the first bottoming electrode is in ohmic contact with the doped polycrystalline silicon layer, and the first covering electrode is stacked on the surface of the first bottoming electrode. The electrodes in the TOPCon solar cell comprise the bottoming electrode and the covering electrode, the bottoming electrode is an ohmic contact electrode, the covering electrode is a transmission electrode, the bottoming electrode can be made of a base metal material, the covering electrode can be made of a silver-coated copper material, and the silver consumption of the electrodes can be greatly reduced by optimizing the electrode structure and the material, so that the production cost is reduced, and the production efficiency is improved. And the metallization cost is reduced.

Description

Technical Field

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

[0002] Developing clean energy technology based on photovoltaic power generation is one of the important ways to solve the current energy supply problem and reduce greenhouse gas emissions. Crystalline silicon solar cells are still the mainstream products in the current commercial photovoltaic power generation field due to their excellent photovoltaic performance and relatively low manufacturing costs. In recent years, the iteration speed of crystalline silicon solar cell technology has accelerated, from the initial large-scale mass production of p-type Al-BSF cells to the PERC cells in the past few years, and then to the n-type TOPCon cells and HJT cells that have gradually dominated recently, the cell efficiency has been continuously improved.

[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. Since silver paste is used on both sides of the n-type cell, the silver paste consumption is significantly increased compared to PERC cells, and the metallization cost is high. In addition, due to the limitations of silver reserves and prices, the cost reduction space of the existing metallization technology is limited, which is one of the key factors restricting the acceleration of the industrialization of high-efficiency n-type cells. 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] 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 TOPCon batteries are solar cells that need to form ohmic contacts through high-temperature sintering, if silver-coated copper paste is directly applied to TOPCon batteries, the silver shell will fall off during the high-temperature sintering process, and copper ions will migrate to the silicon substrate of the battery, seriously reducing the performance and reliability of the battery. Therefore, silver-coated copper paste cannot be directly applied to TOPCon batteries. At present, TOPCon batteries in the industry still use the method of double-sided screen printing of silver paste to prepare electrodes. The consumption of silver paste is large, resulting in high metallization costs for TOPCon batteries.

[0005] Therefore, in view of the above technical problems, it is necessary to provide a TOPCon solar cell and photovoltaic module. Utility Model Content

[0006] The utility model aims to provide a TOPCon solar cell and a photovoltaic module, which can reduce silver consumption and improve the reliability of the cell by optimizing the electrode structure.

[0007] In order to achieve the above purpose, the technical solution provided by an embodiment of the present utility model is as follows:

[0008] A TOPCon solar cell, comprising a silicon substrate and a tunneling layer, a doped polysilicon layer, a first dielectric layer and a first electrode stacked in sequence on the back side of the silicon substrate, wherein the first dielectric layer is provided with a first opening penetrating to the surface of the doped polysilicon layer, 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 doped polysilicon layer, and the first covering electrode is stacked on the surface of the first bottom electrode.

[0009] 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 less than or equal to the width of the first bottom electrode.

[0010] In one embodiment, the first dielectric layer is AlO X Layer, SiN X Layer, SiO X N Y Layer, SiO X A combination of one or more layers having a thickness of 60 nm to 100 nm; and / or,

[0011] The width of the first opening is 1 μm to 40 μm or 40 μm to 400 μm.

[0012] In one embodiment, the thickness of the first bottom electrode is 0.1 μm to 1 μm; and / or,

[0013] The width of the first bottom electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or,

[0014] The thickness of the first covering electrode is 2 μm to 20 μm; and / or,

[0015] The width of the first covering electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or,

[0016] The first bottoming electrode is a base metal electrode, and the base metal is any one or more of nickel and titanium; the first covering electrode is a silver-coated copper slurry electrode.

[0017] In one embodiment, the TOPCon solar cell also includes an emitter formed on the front side of the silicon substrate and a second dielectric layer and a second electrode stacked on the emitter, the second dielectric layer is provided with a second opening penetrating to the emitter, the second electrode fills the second opening and is in ohmic contact with the emitter.

[0018] In one embodiment, 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 emitter, and the second covering electrode is stacked on the surface of the second bottom electrode.

[0019] In one embodiment, the second bottom electrode fills the second opening and covers a portion of the surface of the dielectric layer, and the width of the second covering electrode is less than or equal to the width of the second bottom electrode.

[0020] In one embodiment, the second dielectric layer is AlO X Layer, SiN X Layer, SiO X N Y Layer, SiO X A combination of one or more layers having a thickness of 10 nm to 100 nm; and / or,

[0021] The second opening has a width of 1 μm to 40 μm or 40 μm to 400 μm.

[0022] In one embodiment, the thickness of the second bottom electrode is 0.1 μm to 1 μm; and / or,

[0023] The width of the second bottom electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or,

[0024] The thickness of the second covering electrode is 2 μm to 20 μm; and / or,

[0025] The width of the second covering electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or,

[0026] The second bottoming electrode is a base metal electrode, and the base metal is any one or more of nickel and titanium; the second covering electrode is a silver-coated copper slurry electrode.

[0027] The technical solution provided by an embodiment of the present utility model is as follows:

[0028] A photovoltaic assembly comprises a plurality of the above-mentioned TOPCon solar cells.

[0029] Compared with the prior art, the utility model has the following beneficial effects:

[0030] The electrodes in the TOPCon 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 material, the silver consumption of the electrode can be greatly reduced, and the metallization cost can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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.

[0032] Figure 1 This is a schematic diagram of the structure of the TOPCon solar cell in the first embodiment of the utility model;

[0033] Figure 2 This is a schematic diagram of the structure of the first electrode in the first embodiment of the utility model;

[0034] Figure 3 This is a schematic diagram of the structure of the second electrode in the first embodiment of the utility model;

[0035] Figure 4 This is a schematic diagram of the structure of a TOPCon solar cell in the second embodiment of the utility model;

[0036] Figure 5 Schematic diagram of the structure of the first electrode in the third embodiment of the present utility model. DETAILED DESCRIPTION

[0037] 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.

[0038] 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.

[0039] The utility model discloses a TOPCon solar cell, comprising a silicon substrate and a tunneling layer, a doped polysilicon layer, a first dielectric layer and a first electrode which are sequentially stacked on the back side of the silicon substrate, wherein the first dielectric layer is provided with a first opening penetrating to the surface of the doped polysilicon layer, 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 doped polysilicon layer, and the first covering electrode is stacked on the surface of the first bottom electrode.

[0040] Preferably, the TOPCon solar cell also includes an emitter formed on the front side of the silicon substrate and a second dielectric layer and a second electrode stacked on the emitter, the second dielectric layer is provided with a second opening penetrating to the emitter, the second electrode is filled in the second opening and is in ohmic contact with the emitter; the second electrode includes 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 emitter, and the second covering electrode is stacked on the surface of the second bottom electrode.

[0041] 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.

[0042] The present invention is further described below in conjunction with specific embodiments.

[0043] Ginseng Figure 1 The figure shows a schematic structural diagram of a TOPCon solar cell in a first embodiment of the present invention. The TOPCon solar cell includes a silicon substrate 10 and a tunneling layer 11, a doped polysilicon layer 12, a first dielectric layer 13 and a first electrode 17 stacked in sequence on the back side of the silicon substrate. The figure also includes an emitter 14 formed on the front side of the silicon substrate and a second dielectric layer and a second electrode 18 stacked on the emitter.

[0044] Exemplarily, the silicon substrate 10 in this embodiment is an N-type single crystal silicon wafer, the doped polysilicon layer 12 is a phosphorus doped polysilicon layer, and the emitter 14 is a P+ emitter formed by boron diffusion. Preferably, the front side of the silicon wafer is a pyramid structure velvet surface, and the back side of the silicon wafer is a polished surface.

[0045] The tunneling layer 11 is a SiO2 layer with a thickness of 1nm to 3nm; the doped polysilicon layer 12 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 1E20atoms / cm 3 ~1E21 atoms / cm 3 The thickness of the emitter 14 is 0.6 μm to 1.5 μm, the square resistance is 60 Ω / □ to 600 Ω / □, and the surface boron doping concentration is 1E18 atoms / cm 3~1E20atoms / cm 3 .

[0046] In addition, the first dielectric layer 13 is AlO X Layer, SiN X Layer, SiO X N Y Layer, SiO X A combination of one or more layers, preferably SiN X The first dielectric layer 13 has a first opening (unnumbered) extending through the surface of the doped polysilicon layer 12, and the width of the first opening is 1 μm to 40 μm or 40 μm to 400 μm. Specifically, the width of the first opening corresponding to the fine gate line is 1 μm to 40 μm, and the width of the first opening corresponding to the main gate line or the welding Pad point is 40 μm to 400 μm.

[0047] In this embodiment, the first electrode 17 is a gate line electrode, which at least includes a plurality of main gate lines and fine gate lines, and the main gate lines and the fine gate lines are vertically distributed.

[0048] Ginseng Figure 2 The first electrode 17 is a schematic diagram of the structure, which includes a first bottom electrode 171 and a first cover electrode 172. The first bottom electrode 171 fills the first opening and is in ohmic contact with the doped polysilicon layer 12. The first cover electrode layer 172 is stacked on the surface of the first bottom electrode 171. Figure 1 As shown, the first bottom electrode 171 fills the first opening and covers a portion of the surface of the first dielectric layer 13 , and the width of the first covering electrode 172 is smaller than the width of the first bottom electrode 171 .

[0049] Illustratively, in this embodiment, the thickness of the first bottom electrode 171 is 0.1μm to 1μm, and for the fine gate lines and the main gate lines, the widths of the first bottom electrode 171 are 5μm to 50μm and 50μm to 500μm, respectively; the thickness of the first covering electrode 172 is 2μm to 20μm, and for the fine gate lines and the main gate lines, the widths of the first covering electrode 172 are 5μm to 50μm and 50μm to 500μm, respectively.

[0050] Furthermore, the first bottom electrode 171 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 172 is a silver-coated copper slurry electrode, which is formed by printing the silver-coated copper slurry and curing it.

[0051] In the present embodiment, the first covering electrode 172 is prepared on the first bottoming electrode 171 by a printing process. The width of the first covering electrode 172 is smaller than that of the first bottoming electrode 171, which can ensure the positioning accuracy during the printing process and avoid printing deviation of the first covering electrode 172, thereby ensuring the conduction performance of carriers between the first covering electrode 172 and the first bottoming electrode 171 and improving battery efficiency.

[0052] The first electrode in this embodiment is a composite electrode composed of a first bottom electrode 171 and a first covering electrode 172. The first bottom electrode 171 is an ohmic contact electrode in contact with the doped polysilicon layer, and the first covering electrode 172 is a transmission electrode for collecting and conducting carriers. The structure and material of the electrode are designed in a targeted manner according to its function, which can ensure that the entire electrode is in ohmic contact with the doped polysilicon layer and has good current collection and conduction capabilities. At the same time, it can greatly reduce silver consumption and reduce metallization costs.

[0053] The second dielectric layer in this embodiment is AlO X Layer, SiN X Layer, SiO X N Y Layer, SiO X The second dielectric layer comprises a passivation layer 15 and an anti-reflection layer 16 which are sequentially stacked on the emitter 14. The passivation layer is SiO X 、AlO X A combination of one or more of the above, preferably an Al2O3 layer with a thickness of 1nm to 10nm, and an anti-reflection layer of SiN X 、SiO X N Y 、SiO X One or more combinations thereof, preferably SiN X Layer with a thickness of 60nm to 80nm.

[0054] A second opening (unnumbered) is provided on the passivation layer 15 and the anti-reflection layer 16, which passes through the emitter 14. Similarly, the width of the second opening is 1μm to 40μm or 40μm to 400μm. Specifically, the width of the second opening corresponding to the fine gate line is 1μm to 40μm, and the width of the second opening corresponding to the main gate line or the welding pad point is 40μm to 400μm.

[0055] Ginseng Figure 3The figure shows a schematic diagram of the structure of the second electrode 18 in this embodiment, which includes a second bottom electrode 181 and a second covering electrode 182. The second bottom electrode 181 fills the second opening and is in ohmic contact with the emitter 14, and the second covering electrode layer 182 is stacked on the surface of the second bottom electrode 181. The specific structure of the second electrode 18 in this embodiment is exactly the same as that of the first electrode 17, and will not be repeated here.

[0056] Ginseng Figure 4 The figure shows a schematic diagram of the structure of a TOPCon solar cell in the second embodiment of the utility model, which includes a silicon substrate 10 and a tunneling layer 11, a doped polysilicon layer 12, a first dielectric layer 13 and a first electrode 17 stacked in sequence on the back of the silicon substrate, and also includes an emitter 14 formed on the front of the silicon substrate and a second dielectric layer (a passivation layer 15 and an anti-reflection layer 16) stacked on the emitter and a second electrode 18. The structure of the TOPCon solar cell in this embodiment is basically the same as that in the first embodiment, and the only difference is that the electrodes are different.

[0057] Specifically, the first electrode 17 in this embodiment is completely the same as the first electrode in the first embodiment, and the second electrode 18 is a silver electrode or a silver-aluminum electrode, and the second electrode 18 is a gate electrode, wherein the width of the fine gate line is 5 μm to 50 μm, and the width of the main gate line is 50 μm to 500 μm. The second electrode 18 is screen-printed with silver paste or silver-aluminum paste, and is sintered at high temperature (sintering temperature 750° C. to 850° C.) or sintered at high temperature (sintering temperature 700° C. to 800° C.) combined with laser-assisted current injection, so that an ohmic contact is formed on the front emitter.

[0058] Ginseng Figure 5 The figure is a schematic diagram of the structure of the first electrode in the third embodiment of the utility model. The structure of the TOPCon 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 172 is equal to the width of the first bottoming electrode 171, and the first covering electrode 172 is covered on the entire surface of the first bottoming electrode 171 by a printing process.

[0059] Likewise, the structure of the second electrode is the same as that of the first electrode, and will not be described again herein.

[0060] 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.

[0061] It can be seen from the above technical solution that the utility model has the following beneficial effects:

[0062] The electrodes in the TOPCon 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 material, the silver consumption of the electrode can be greatly reduced, and the metallization cost can be reduced.

[0063] 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.

[0064] 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. A TOPCon solar cell, characterized in that: The TOPCon solar cell includes a silicon substrate and a tunneling layer, a doped polysilicon layer, a first dielectric layer and a first electrode stacked in sequence on the back side of the silicon substrate. The first dielectric layer is provided with a first opening penetrating to the surface of the doped polysilicon layer. 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 doped polysilicon layer. The first covering electrode is stacked on the surface of the first bottom electrode.

2. The TOPCon 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. The width of the first covering electrode is less than or equal to the width of the first bottom electrode.

3. The TOPCon solar cell according to claim 1, characterized in that: The first dielectric layer is AlO X Layer, SiN X Layer, SiO X N Y Layer, SiO X A combination of one or more layers having a thickness of 60 nm to 100 nm; and / or, The first opening has a width of 1 μm to 40 μm or 40 μm to 400 μm.

4. The TOPCon 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 width of the first bottom electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or, The thickness of the first covering electrode is 2 μm to 20 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 first bottoming electrode is a base metal electrode, and the base metal is any one or more of nickel and titanium; the first covering electrode is a silver-coated copper slurry electrode.

5. The TOPCon solar cell according to claim 1, characterized in that: The TOPCon solar cell also includes an emitter formed on the front side of the silicon substrate and a second dielectric layer and a second electrode stacked on the emitter. The second dielectric layer is provided with a second opening penetrating to the emitter. The second electrode fills the second opening and is in ohmic contact with the emitter.

6. The TOPCon solar cell according to claim 5, characterized in that: 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 emitter. The second covering electrode is stacked on the surface of the second bottom electrode.

7. The TOPCon solar cell according to claim 6, characterized in that: The second bottom electrode fills the second opening and covers a portion of the surface of the dielectric layer. The width of the second covering electrode is less than or equal to the width of the second bottom electrode.

8. The TOPCon solar cell according to claim 5, characterized in that: The second dielectric layer is AlO X Layer, SiN X Layer, SiO X N Y Layer, SiO X A combination of one or more layers having a thickness of 10 nm to 100 nm; and / or, The second opening has a width of 1 μm to 40 μm or 40 μm to 400 μm.

9. The TOPCon solar cell according to claim 7, characterized in that: The thickness of the second bottom electrode is 0.1 μm to 1 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 thickness of the second covering electrode is 2 μm to 20 μm; and / or, The width of the second covering electrode is 5 μm to 50 μm or 50 μm to 500 μm; and / or, The second bottoming electrode is a base metal electrode, and the base metal is any one or more of nickel and titanium; the second covering electrode is a silver-coated copper slurry electrode.

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

Images