Back contact solar cell

Abstract

The utility model provides a back contact type solar cell, and belongs to the technical field of solar cells. The back contact solar cell includes: a substrate; the doped layer is formed on the substrate and comprises N doped regions and P doped regions which are alternately arranged at intervals; the electrode layer is formed on the doping layer and comprises an N region electrode formed on the N doping region and a P region electrode formed on the P doping region; wherein the P-doped region, the N-doped region, the P-region electrode and the N-region electrode are constructed to meet the size relationship shown in the following formula: 1 / 2gt; a WP electrode / WP region gt; a WN electrode / WN region gt; the width of the WP electrode is equal to the width of the P-region electrode, the width of the WN electrode is equal to the width of the N-region electrode, the width of the WP region is equal to the width of the P-doped region, and the width of the WN region is equal to the width of the N-doped region. The sizes of the P-doped region, the N-doped region, the P-region electrode and the N-region electrode are designed, the passivation effect difference of the N-doped region and the P-doped region can be considered, the contact resistance of the N-doped region and the P-doped region is matched, and the cell efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of solar cells, and in particular to a back-contact solar cell. Technical Background

[0002] An interdigitated back contact (IBC) cell is a cell in which the emitter and the corresponding P-region electrode and N-region electrode are all located on the back of the cell. There is no metal grid line on the front, so there is no metal electrode shading. It is a solar cell with relatively high conversion efficiency.

[0003] By optimizing the surface passivation of IBC cells, various cell structures have been derived, such as the Polycrystalline silicon (poly-Si) on Oxide (POLO)-Interdigitated Back Contacted (POLO-IBC) cell, which has a laboratory conversion efficiency of 27.5%. Its biggest feature is the selective passivation of carriers, and there is no recombination loss on the metal contact surface. Another example is the TBC cell formed by the superposition of the Tunnel Oxide Passivated Contact (TOPcon) cell and the IBC cell.

[0004] However, in the related art, there is no obvious difference in the structural size of the P-doped region and the N-doped region of these back-contact solar cells. The impact of the passivation difference between the P-doped region and the N-doped region itself on the battery is not taken into account. At the same time, the impact of the ratio of the electrode width to its bandwidth is not taken into account. There is still room for improvement in battery efficiency. Utility Model Content

[0005] In view of this, the main purpose of the utility model is to provide a back-contact solar cell, which can take into account the passivation difference between the P-doped region and the N-doped region themselves, as well as the matching of the contact resistance, so as to improve the cell efficiency.

[0006] In order to achieve the above purpose, the technical solution of the utility model is as follows:

[0007] According to an embodiment of the utility model, a back-contact solar cell is provided, comprising a substrate, a doping layer and an electrode layer, wherein: the doping layer is formed on the substrate, comprising an N-doping region and a P-doping region, and the N-doping region and the P-doping region are alternately arranged; the electrode layer is formed on the doping layer, comprising an N-region electrode and a P-region electrode, the N-region electrode is formed on the N-doping region, and the P-region electrode is formed on the P-doping region; wherein the P-doping region, the N-doping region, the P-region electrode and the N-region electrode are constructed to satisfy the size relationship shown in formula (1):

[0008] 1 / 2>W P电极 / W P区 >W N电极 / W N区 >8 / 1000, formula (1);

[0009] Among them, W P电极 is the width of the P region electrode, W N电极 is the width of the N-region electrode, W P区 is the width of the P-doped region, W N区 is the width of the N-doped region.

[0010] According to an embodiment of the present invention, the width of the N-doped region is greater than the width of the P-doped region; and / or the width of the N-region electrode is smaller than the width of the P-region electrode.

[0011] According to an embodiment of the present invention, the widths of the N-doped region and the P-doped region are 300-1000 μm respectively; the widths of the N-region electrode and the P-region electrode are 8-150 μm respectively.

[0012] According to an embodiment of the utility model, the back-contact solar cell also includes: a surface passivation layer, formed between the doping layer and the electrode layer, wherein the surface passivation layer is respectively provided with a first opening and a second opening, the first openings are arranged in an array on the area of ​​the surface passivation layer opposite to the N-doped area; the second openings are arranged in an array on the area of ​​the surface passivation layer opposite to the P-doped area; wherein the N-area electrode contacts the N-doped area through the first opening, and the P-area electrode contacts the P-doped area through the second opening.

[0013] According to an embodiment of the present invention, the first opening and the second opening are configured to satisfy the dimensional relationship shown in formula (2): 40 / 300>S P开膜 / S P区 >S N开膜 / S N区 >5 / 1000, formula (2); where S N开膜 is the total area of ​​the first opening, S P开膜 is the total area of ​​the second opening, S N区 is the area of ​​the N-doped region, S P区 is the area of ​​the P-doped region.

[0014] According to an embodiment of the present invention, the equivalent width W of the first opening is 1,等效 and the equivalent width W of the second opening 2,等效 Satisfy the relationship shown in formula (3)-formula (4): 1>W 1,等效 / W N电极 >5 / 150, (3); 1>W 2,等效 / W P电极>5 / 150, (4); among them, W 1,等效 =S N开膜 / L N区 , W 2,等效 =S P开膜 / L P区 , L N区 is the length of the N-doped region, L P区 is the length of the P-doped region.

[0015] According to an embodiment of the present invention, the equivalent width of the first opening and the equivalent width of the second opening are 5-40 μm respectively.

[0016] According to an embodiment of the utility model, the electrode layer also includes: a first seed layer deposited in the first opening and located between the N-doped region and the N-region electrode; and a second seed layer deposited in the second opening and located between the P-doped region and the P-region electrode.

[0017] According to an embodiment of the utility model, the back-contact solar cell of the utility model further includes: a tunneling oxide layer formed between the substrate and the N-doped region, and between the substrate and the P-doped region; wherein the substrate is a doped polysilicon layer, and the N-doped region and the P-doped region are arranged in a forked finger shape.

[0018] According to an embodiment of the utility model, the back-contact solar cell of the utility model further includes: a tunneling oxide layer formed between one of the N-doped region and the P-doped region and the substrate; an intrinsic amorphous silicon layer formed between the other of the N-doped region and the P-doped region and the substrate, wherein the substrate is a doped polycrystalline silicon layer, and the N-doped region and the P-doped region are arranged in a forked finger shape.

[0019] According to the embodiments of the present invention, for back-contact solar cells, different types of doping are used in the P-doped region and the N-doped region, and there are certain differences in their conductivity, and the conductivity of the N-doped region is generally better than that of the P-doped region. At the same time, the passivation effect of the P-doped region is worse than that of the N-doped region. Therefore, the present invention can take into account the difference in the passivation effects of the N-doped region and the P-doped region by designing the sizes of the P-doped region, the N-doped region, the P-region electrode and the N-region electrode, and at the same time match the contact resistance of the N-doped region and the P-doped region, thereby effectively improving the battery performance, including the improvement of the battery efficiency and the opening voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A cross-sectional view of a back-contact solar cell in one embodiment of the utility model;

[0021] Figure 2 A top view of a back-contact solar cell in one embodiment of the utility model;

[0022] Figure 3This is a schematic diagram of the P-region electrode and the N-region electrode of a back-contact solar cell having equal widths in one embodiment of the utility model;

[0023] Figure 4 It is a schematic diagram of a back-contact solar cell with equal widths of a P-doped region and an N-doped region in one embodiment of the utility model;

[0024] Figure 5 is a cross-sectional view of a back-contact solar cell in another embodiment of the present invention;

[0025] Figure 6 It is a schematic diagram of another embodiment of the present invention in which the areas of the P-doped region and the N-doped region of the back-contact solar cell are equal;

[0026] Figure 7 It is a schematic diagram of another embodiment of the utility model in which the total area of ​​the first openings and the total area of ​​the second openings of the back-contact solar cell are equal;

[0027] Figure 8 A cross-sectional view of a back-contact solar cell in another embodiment of the present invention;

[0028] Fig. 9 It is a cross-sectional view of a back-contact solar cell in another embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0030] The terms used herein are only for describing specific embodiments and are not intended to limit the utility model. The terms "including", "comprising", etc. used herein indicate the presence of features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components. All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used here should be interpreted as having meanings consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0031] In order to further improve the cell efficiency of back-contact solar cells, in the process of realizing the concept of the utility model, it was found that the sizes of the P-doped region, the N-doped region, the P-region electrode and the N-region electrode can be designed to improve the cell passivation effect, reduce the contact resistance, and thus improve the cell efficiency.

[0032] Specifically, according to an embodiment of the present invention, a back-contact solar cell is provided. Figure 1It is a cross-sectional view of a back-contact solar cell in one embodiment of the present invention.

[0033] like Figure 1 As shown, a back-contact solar cell according to an embodiment of the present invention comprises a substrate 101, a doping layer 102 and an electrode layer 103, wherein: the doping layer 102 is formed on the substrate 101, and comprises an N-doping region 1021 and a P-doping region 1022, and the N-doping region 1021 and the P-doping region 1022 are alternately arranged; the electrode layer 103 is formed on the doping layer 102, and comprises an N-region electrode 1031 and a P-region electrode 1032, and the N-region electrode 1031 is formed on the N-doping region 1021, and the P-region electrode 1032 is formed on the P-doping region 1022; wherein the P-doping region 1022, the N-doping region 1021, the P-region electrode 1032 and the N-region electrode 1031 are constructed to satisfy the size relationship shown in formula (1):

[0034] 1 / 2>W P电极 / W P区 >W N电极 / W N区 >8 / 1000, formula (1);

[0035] Among them, W P电极 is the width of the P region electrode 1032, W N电极 is the width of the N region electrode 1031, W P区 is the width of the P-doped region 1022, W N区 is the width of the N-doped region 1021. Further optionally, W P电极 / W P区 and W N电极 / W N区 The value can be selected from 1 / 3, 1 / 4, 1 / 5, 1 / 6, 1 / 10, 1 / 50, 1 / 100, etc.

[0036] According to an embodiment of the present invention, the "width" of an electrode refers to the lateral distance above the surface area on which the electrode is formed in the cross section of the electrode. Figure 1 As shown, the width of the N region electrode 1031 is Figure 1 W shown N电极 The “width” of a doped region refers to the lateral distance between the two side interfaces of one of the doped regions in the cross section of the doped layer. Figure 1 As shown, the width of the N-doped region 1021 is Figure 1 W shown N区 It can be understood that the "lateral direction" here refers to a direction parallel to the substrate surface.

[0037] In the embodiments of the utility model, in the back-contact solar cell, it is found that due to the different doping types of the P-doped region and the N-doped region, for example, the P-doped region may be boron-doped and the N-doped region may be phosphorus-doped, there is an obvious difference in their conductivity, and generally the conductivity of the N-doped region is better than that of the P-doped region, while the passivation effect of the P-doped region is worse than that of the N-doped region.

[0038] Therefore, the present invention designs the dimensions of the P-doped region, the N-doped region, the P-region electrode, and the N-region electrode as shown in the above formula (1). For example, when the widths of the P-region electrode and the N-region electrode are the same, the width of the N-doped region is greater than the width of the P-doped region. Based on the passivation effect advantage of the N-doped region, it helps to improve the passivation effect of the battery and improve the opening voltage. For another example, when the widths of the P-doped region and the N-doped region are the same, the width of the P-region electrode is greater than the width of the N-region electrode. This helps to reduce the contact resistance and improve the battery efficiency.

[0039] Therefore, the size design based on the above formula (1) can take into account the difference in passivation effect between the N-doped area and the P-doped area, and at the same time match the contact resistance of the N-doped area and the P-doped area, which can improve the battery performance, specifically including the improvement of battery efficiency and opening voltage.

[0040] In order to better understand the technical solution of the present invention, the structure and size design of the N-doped region 1021 , the P-doped region 1022 , the N-region electrode 1031 and the P-region electrode 1032 are specifically described according to the embodiments of the present invention.

[0041] According to an embodiment of the present invention, the N-doped regions 1021 and the P-doped regions 1022 are alternately arranged on a surface of one side of the substrate 101, such as Figure 1 As shown, it is a schematic diagram of the structure of two doping regions including an arrangement period, and there is an isolation region 1023 between the N-doped region 1021 and the P-doped region 1022, so that the N-doped region 1021 and the P-doped region 1022 are separated from each other at the boundary to prevent current short circuit and prevent direct contact between the materials of the N-doped region 1021 and the P-doped region 1022, thereby improving the stability of the battery and more accurately controlling the width and position of the N-doped region 1021 and the P-doped region 1022.

[0042] According to an embodiment of the utility model, the main material of the N-doped region 1021 and the P-doped region 1022 can be selected from semiconductor materials such as silicon (Si), germanium (Ge), silicon carbide (SiCx) or gallium arsenide (GaAs), and these semiconductor materials can be amorphous, microcrystalline, single crystal, nanocrystalline or polycrystalline. By introducing donor impurities such as phosphorus (P), arsenic (As) or antimony (Sb) into the aforementioned semiconductor materials, the N-type material of the N-doped region 1021 is obtained; by introducing acceptor impurities such as boron (B), aluminum (Al) or gallium (Ga) into the aforementioned semiconductor materials, the P-type material of the P-doped region 1022 is obtained. Due to the different doping types, there will be a certain difference in the conductivity of the N-doped region 1021 and the P-doped region 1022. Generally speaking, taking the N-doped region 1021 as phosphorus doped and the P-doped region 1022 as boron doped as an example, the conductivity of the N-doped region 1021 is significantly better than that of the P-doped region 1022.

[0043] According to the embodiments of the present utility model, Figure 1 As shown, the back-contact solar cell also includes a surface passivation layer 104 formed on the doping layer 103, which plays a role in preventing oxidation or corrosion of the electrode surface, reducing the surface recombination rate, increasing the photocurrent, strengthening the built-in electric field, and enhancing carrier collection. Among them, the electrode layer 103 is formed on the surface passivation layer 104. The surface passivation layer can be made of materials such as silicon nitride.

[0044] According to an embodiment of the utility model, the preparation method of the N-region electrode and the P-region electrode in the electrode layer 103 may respectively include: printing the electrode paste on the surface passivation layer 104 by a printing process such as screen printing, inkjet printing, etc., and then sintering the electrode paste to pass through the surface passivation layer 104 and contact the doped region. Thus, the N-region electrode is formed on the N-doped region and connected through the contact bridge, and the P-region electrode is formed on the P-doped region and connected through the contact bridge, and the contact resistance is reduced by the contact bridge formed by sintering.

[0045] Figure 2 FIG. 1 is a top view of a back-contact solar cell according to an embodiment of the present invention, which shows the structure of the N-region electrode 1031 and the P-region electrode 1032. Specifically, Figure 2 As shown, the N-region electrode 1031 and the P-region electrode 1032 are respectively auxiliary gate lines, which are arranged crosswise with each other. The N-region electrode 1031 can be connected to the N-region main gate line 1034, and the current is collected to the N-region main gate line 1034 through the N-region electrode 1031; the P-region electrode 1032 can be connected to the P-region main gate line 1035, and the current is collected to the P-region main gate line 1035 through the P-region electrode 1031.

[0046] In some embodiments of the present invention, Figure 1 and Figure 2 The preparation method of the back-contact solar cell shown mainly includes: depositing a stacked structure including a doping layer 102 and a surface passivation layer 103 on a substrate 101 to obtain a cell precursor, printing a secondary grid paste and a main grid paste on the cell precursor respectively, and sintering to form an electrode layer 103 including an N-region electrode 1031 and a P-region electrode 1032. The slurry can be applied by screen printing, inkjet printing, etc.

[0047] According to the embodiment of the utility model, the printing paste of the P-region electrode and the N-region electrode can be silver paste, aluminum paste or copper paste, etc., and the sintering temperature is 600-900°C, for example, it can be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, etc. Considering factors such as cost and electrical performance, the widths of the N-doped region, the P-doped region, the N-region electrode and the P-region electrode are limited.

[0048] According to an embodiment of the utility model, the widths of the N-doped region and the P-doped region may be 300-1000μm, for example, 300μm, 400μm, 500μm, 600μm, 800μm, 1000μm, etc.; the widths of the N-region electrode and the P-region electrode may be 8-150μm, for example, 8μm, 20μm, 40μm, 80μm, 120μm, 150μm, etc.

[0049] Figure 3 It is a schematic diagram showing that the widths of the P-region electrode and the N-region electrode of a back-contact solar cell are equal in one embodiment of the utility model.

[0050] like Figure 3 As shown, it is a limiting case of an embodiment of the present invention, the width W of the P region electrode P电极 Equal to the width W of the N region electrode N电极 , and the width of the N-doped region W N区 Greater than the width W of the P-doped region P区 ; The width of the P-region electrode and the N-region electrode can be 8-50μm, for example, 8μm, 20μm, 40μm, 50μm, etc., the width of the P-doped region can be 100-500μm, for example, 100μm, 200μm, 300μm, 400μm, 500μm, etc., the width of the N-doped region can be 300-1000μm, for example, 300μm, 500μm, 800μm, 1000μm, etc., and the requirements of formula (1) are met at this time.

[0051] Figure 4 It is a schematic diagram showing that the widths of the P-doped region and the N-doped region of a back-contact solar cell are equal in one embodiment of the present invention.

[0052] like Figure 4 As shown in FIG. 1 , another limiting case of an embodiment of the present invention is shown. The width W of the P-doped region is P区 Equal to the width W of the N-doped region N区 , and the width of the P region electrode W P电极 Greater than the width W of the N-region electrode N电极 , the width of the P-doped region and the N-doped region can be 300-1000 μm, for example, 300 μm, 500 μm, 800 μm, 1000 μm, etc., the width of the P-region electrode can be 30-150 μm, for example, 30 μm, 50 μm, 100 μm, 150 μm, etc., and the width of the N-region electrode is 8-50 μm, for example, 8 μm, 20 μm, 40 μm, 50 μm, etc., and the requirements of formula (1) are also met at this time.

[0053] According to the embodiments of the present invention, when the widths of the P-region electrode and the N-region electrode are the same, the width of the N-doped region is greater than the width of the P-doped region, which helps to improve the passivation effect of the battery and increase the opening voltage; when the widths of the P-doped region and the N-doped region are the same, the width of the P-region electrode is greater than the width of the N-region electrode, which helps to reduce the contact resistance and improve the battery efficiency.

[0054] According to the embodiment of the utility model, it is more preferred that the width of the N-doped region is greater than the width of the P-doped region; and / or the width of the N-region electrode is less than the width of the P-region electrode. This is because the conductivity of the N-doped region is better than that of the P-doped region, and the passivation effect of the P-doped region is better than that of the N-doped region. Therefore, when the width of the N-doped region is greater than that of the P-doped region, it is more helpful to improve the passivation effect of the battery and increase the opening voltage; when the width of the N-region electrode is less than that of the P-region electrode, it is more conducive to reducing the contact resistance and improving the battery efficiency. At this time, the requirements of formula (1) are still met, and the battery performance can be effectively improved.

[0055] Figure 5 It is a cross-sectional view of a back-contact solar cell in another embodiment of the present invention.

[0056] like Figure 5 As shown, Figure 1 The structure of the back-contact solar cell shown is similar, and the main difference is that the surface passivation layer 104 is provided with: first openings arranged in an array on the area of ​​the surface passivation layer 104 opposite to the N-doped area 1021; and second openings arranged in an array on the area of ​​the surface passivation layer 104 opposite to the P-doped area 1022; wherein the N-region electrode 1031 passes through the first opening to contact the N-doped area 1021, and the P-region electrode 1032 passes through the second opening to contact the P-doped area 1022. The surface passivation layer 104 is opened, and the electrode passes through the opening to directly contact the doped area, which can reduce the contact resistance between the electrode and the doped area and improve the battery efficiency.

[0057] According to an embodiment of the utility model, further optionally, the first opening and the second opening are configured to satisfy the size relationship shown in formula (2):

[0058] 40 / 300>S P开膜 / S P区 >S N开膜 / S N区 >5 / 1000, formula (2);

[0059] Among them, S N开膜 is the total area of ​​the first opening, S P开膜 is the total area of ​​the second opening, S N区 is the area of ​​the N-doped region 1021, S P区 is the area of ​​the P-doped region 1022. Further optionally, S P开膜 / S P区 and S N开膜 / S N区 The value can be selected from 1 / 5, 1 / 10, 1 / 15, 1 / 20, 1 / 100, 1 / 150, etc.

[0060] According to the embodiment of the present invention, the "area" of the opening refers to the sum of the areas of all the openings in one of the doping regions of the doping layer along the surface of the doping layer, and the "area" of the doping region refers to the area of ​​the surface of the doping region corresponding to these openings. Taking the first opening as an example, the area of ​​the first opening is the total area S of all the openings in an N-doping region. N开膜 , the surface area of ​​the corresponding N-doped region is expressed as S N区 .

[0061] According to the embodiments of the present invention, the total area of ​​the first opening, the total area of ​​the second opening, the area of ​​the N-doped region, and the area of ​​the P-doped region are designed to meet the requirements of formula (2). For example, when the widths of the P-doped region and the N-doped region are equal, that is, the areas are equal, the area of ​​the second opening is larger than the area of ​​the first opening, which is beneficial to reducing the contact resistance and improving the battery efficiency. For another example, when the area of ​​the second opening is equal to the area of ​​the first opening, the area of ​​the P-doped region is smaller than the area of ​​the N-doped region. Based on the passivation effect advantage of the N-doped region, it is helpful to improve the battery passivation effect and increase the opening voltage.

[0062] Therefore, the size design based on the above formula (2) can further take into account the difference in passivation effect between the N-doped area and the P-doped area, and at the same time match the contact resistance of the N-doped area and the P-doped area, which helps to improve the passivation effect, reduce the contact resistance, and improve the battery efficiency.

[0063] According to the embodiment of the present invention, based on practical factors such as the manufacturing process and cost of the electrode, the equivalent width W of the first opening is 1,等效 and the equivalent width W of the second opening2,等效 Satisfy the relationship shown in formula (3)-formula (4):

[0064] 1>W 1,等效 / W N电极 >5 / 150, (3);

[0065] 1>W 2,等效 / W P电极 >5 / 150, (4);

[0066] Among them, W 1,等效 =S N开膜 / L N区 , W 2,等效 =S P开膜 / L P区 , L N区 is the length of the N-doped region, L P区 is the length of the P-doped region.

[0067] In the embodiments of the present utility model, a hole is opened in the surface passivation layer by laser opening, and the final electrode is obtained by a deposition process, an electroplating process or a printing process. The actual effective electrode width will be greater than the opening width, or in other words, the electrode area is greater than the opening area, because the electrode realized by the opening method will definitely have overflow width.

[0068] According to the embodiment of the utility model, the width of the N-doped region and the P-doped region, and the equivalent width of the first opening and the second opening are limited in consideration of factors such as cost and electrical performance. The width of the N-doped region and the P-doped region can be 300-1000 μm, for example, 300 μm, 400 μm, 500 μm, 600 μm, 800 μm, 1000 μm, etc.; the equivalent width of the first opening and the equivalent width of the second opening can be 5-40 μm, for example, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, etc.

[0069] According to an embodiment of the utility model, the preparation method of the N-region electrode and the P-region electrode includes: laser opening the battery precursor on which the doping layer 102 and the surface passivation layer 103 have been deposited, removing the surface passivation layer 103 at the graphic position corresponding to the P-region electrode and the N-region electrode, obtaining the first opening and the second opening, and then forming the final N-region electrode and the P-region electrode in the regions of the first opening and the second opening, respectively.

[0070] According to the embodiment of the utility model, further optionally, the N-region electrode and the P-region electrode can be formed by direct electroplating in the regions of the first opening and the second opening, or the first seed layer can be deposited in the first opening, and the second seed layer can be deposited in the second opening, and then the printing paste of the N-region electrode and the P-region electrode, such as copper paste, aluminum paste, etc., is coated on the first seed layer and the second seed layer by a printing process, respectively, and the annealing temperature is 200-400°C, such as 200°C, 300°C, 400°C, etc. The first seed layer and the second seed layer can be metals such as nickel, copper, and tin, etc.

[0071] According to an embodiment of the utility model, the electrode layer also includes: a first seed layer deposited in the first opening and located between the N-doped region and the N-region electrode; and a second seed layer deposited in the second opening and located between the P-doped region and the P-region electrode.

[0072] In an embodiment of the utility model, a seed layer is first deposited or electroplated in the opening through a deposition process or an electroplating process. The seed layer is a material with excellent conductivity, usually metals such as nickel, copper, and tin. This is mainly because it can form a good ohmic contact with the semiconductor material, reduce the contact resistance between the electrode and the doped region, and improve the adhesion between the N-region electrode and the P-region electrode, thereby helping to improve battery efficiency and electrode stability.

[0073] Figure 6 This is a schematic diagram of another embodiment of the present invention in which the areas of the P-doped region and the N-doped region of a back-contact solar cell are equal.

[0074] like Figure 6 As shown in FIG. 1 , it is a limiting case of another embodiment of the present invention, where the area S of the P-doped region is P区 = Area of ​​N-doped region S N区 , the total area of ​​the second opening S P开膜 >Total area of ​​the first opening S N开膜 , where the circular openings have the same opening area, i.e., the diameters (d) of the circular openings are equal, and the spacing between the first openings (L 1 )>The distance between the second openings (L 2 ), when summing up the total opening area, it can be obtained that the total area of ​​the second opening is greater than the total area of ​​the first opening, and the requirement of formula (2) is met at this time.

[0075] Figure 7 This is a schematic diagram showing that the total area of ​​the first openings and the total area of ​​the second openings of a back-contact solar cell are equal in another embodiment of the present invention.

[0076] like Figure 7 As shown in FIG. 1 , another limiting case of another embodiment of the utility model is shown. The total area S of the first opening is N开膜 = Total area of ​​the second opening SP开膜 , the area of ​​N-doped region S N区 Greater than the area S of the P-doped region P区 , where the ellipse is an opening, the opening area is the same, and the spacing between the first openings = the spacing between the second openings, then the total opening area is the same, and the area of ​​the N-doped region is larger than the area of ​​the P-doped region, and at this time, the requirements of formula (2) are also met.

[0077] According to an embodiment of the present invention, the substrate 101 may be a semiconductor material such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), etc. From the perspective of conductivity type, the substrate 101 may be an intrinsic conductive substrate, an N-type conductive substrate, or a P-type conductive substrate. Compared with an intrinsic conductive substrate, an N-type conductive substrate or a P-type conductive substrate has better conductivity, which is beneficial to improving the efficiency of a back-contact solar cell.

[0078] According to an embodiment of the present invention, the back-contact solar cell of the present invention may be an IBC cell, a POLO-IBC cell, a TBC cell, a TBC-HTJ (heterojunction) combined cell, preferably a TBC cell or a TBC-HTJ (heterojunction) combined cell.

[0079] According to an embodiment of the present utility model, further optionally, for a TBC battery, Figure 1 and Figure 2 The structure shown was optimized based on the Figure 8 FIG. 4 is a cross-sectional view of a back-contact solar cell in another embodiment of the present invention. Figure 8 As shown, Figure 1 and Figure 2 The structure shown is similar, except that the back-contact solar cell also includes: a tunneling oxide layer 105, formed between the substrate 101 and the N-doped region 1021, and between the substrate 101 and the P-doped region 1022; wherein the substrate 101 is a doped polysilicon layer, and the N-doped region 1021 and the P-doped region 1022 are arranged in a forked finger shape.

[0080] In the embodiments of the present invention, a passivation method (passivation contact) using a tunneling oxide layer and polysilicon can achieve an excellent surface passivation effect, greatly improving the cell efficiency; combining back-contact solar cells with passivation contact technology can achieve higher cell conversion efficiency.

[0081] According to the embodiments of the present invention, the N-doped region and the P-doped region are designed to be arranged in an interdigitated manner, which can increase the photoelectric conversion efficiency of the solar cell, and also help reduce the recombination loss of the current inside the solar cell, thereby improving the current collection efficiency.

[0082] According to an embodiment of the present invention, further optionally, for a TBC-HJT (heterojunction) combined battery, Fig. 9 FIG. 4 is a cross-sectional view of a back-contact solar cell in another embodiment of the present invention. Fig. 9 As shown, Figure 1 and Figure 2 The structure shown is similar, except that the back-contact solar cell further includes a tunneling oxide layer 1051 and an intrinsic amorphous silicon layer 1052, wherein the tunneling oxide layer 1051 is formed between the N-doped region 1021 and the substrate 101; the intrinsic amorphous silicon layer 1052 is formed between the P-doped region 1022 and the substrate 101. Of course, in other embodiments, the positions of the tunneling oxide layer 1051 and the intrinsic amorphous silicon layer 1052 can also be interchanged.

[0083] According to the embodiments of the present utility model, a battery structure using a tunneling oxidation passivation contact structure and a heterojunction structure combined with passivation is helpful to improve battery efficiency and stability.

[0084] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A back-contact solar cell, characterized in that: include: substrate; A doping layer is formed on the substrate, the doping layer comprises an N-doping region and a P-doping region, and the N-doping region and the P-doping region are alternately arranged; an electrode layer, formed on the doped layer, the electrode layer comprising an N-region electrode and a P-region electrode, the N-region electrode being formed on the N-doped region, and the P-region electrode being formed on the P-doped region; The P-doped region, the N-doped region, the P-region electrode and the N-region electrode are configured to satisfy the size relationship shown in formula (1): 1 / 2 > W P电极 / W P区 >W N电极 / W N区 > 8 / 1000, Equation (1); Among them, W P电极 is the width of the P region electrode, W N电极 is the width of the N-region electrode, W P区 is the width of the P-doped region, W N区 is the width of the N-doped region.

2. The back-contact solar cell according to claim 1, characterized in that: The width of the N-doped region is greater than the width of the P-doped region; and / or The width of the N-region electrode is smaller than the width of the P-region electrode.

3. The back-contact solar cell according to claim 1 or 2, characterized in that: The widths of the N-doped region and the P-doped region are 300-1000 μm respectively; The widths of the N-region electrode and the P-region electrode are 8-150 μm respectively.

4. The back-contact solar cell according to claim 1, characterized in that: The back-contact solar cell further comprises: A surface passivation layer is formed between the doping layer and the electrode layer, wherein the surface passivation layer is respectively provided with: first openings are arranged in an array on a region of the surface passivation layer opposite to the N-doped region; and The second openings are arranged in an array on a region of the surface passivation layer opposite to the P-doped region; The N-region electrode passes through the first opening to contact the N-doped region, and the P-region electrode passes through the second opening to contact the P-doped region.

5. The back-contact solar cell according to claim 4, characterized in that: The first opening and the second opening are configured to satisfy the dimensional relationship shown in formula (2): 40 / 300>S P开膜 / S P区 >S N开膜 / S N区 >5 / 1000, formula (2); Among them, S N开膜 is the total area of ​​the first opening, S P开膜 is the total area of ​​the second opening, S N区 is the area of ​​the N-doped region, S P区 is the area of ​​the P-doped region.

6. The back-contact solar cell according to claim 5, characterized in that: The equivalent width W of the first opening 1,等效 and the equivalent width W of the second opening 2,等效 Satisfy the relationship shown in formula (3)-formula (4): 1>In 1,等效 / IN N电极 >5 / 150, (3); 1>In 2,等效 / IN P电极 >5 / 150, (4); Among them, W 1,等效 =S N开膜 / L N区 , W 2,等效 =S P开膜 / L P区 , L N区 is the length of the N-doped region, L P区 is the length of the P-doped region.

7. The back-contact solar cell according to claim 5 or 6, characterized in that: The equivalent width of the first opening and the equivalent width of the second opening are 5-40 μm respectively.

8. The back-contact solar cell according to claim 4, characterized in that: The electrode layer further comprises: a first seed layer, deposited in the first opening and located between the N-doped region and the N-region electrode; and The second seed layer is deposited in the second opening and is located between the P-doped region and the P-region electrode.

9. The back-contact solar cell according to claim 1, characterized in that: The back-contact solar cell further comprises: A tunneling oxide layer is formed between the substrate and the N-doped region, and between the substrate and the P-doped region; Wherein, the substrate is a doped polysilicon layer, and the N-doped region and the P-doped region are arranged in an interdigitated shape.

10. The back-contact solar cell according to claim 1, characterized in that: The back-contact solar cell further comprises: a tunneling oxide layer formed between one of the N-doped region and the P-doped region and the substrate; and An intrinsic amorphous silicon layer is formed between the other of the N-doped region and the P-doped region and the substrate.

Images