Solar cell

Abstract

The application relates to a solar cell, which comprises a silicon substrate, a first tunneling oxide layer, a first polysilicon layer, a first electrode and a first transparent conductive layer. The silicon substrate has a first surface, which is the back surface of the solar cell; the first tunneling oxide layer is arranged on the first surface; the first polysilicon layer is arranged on the side of the first tunneling oxide layer away from the first surface; the first polysilicon layer comprises a first region and a second region; the thickness h1 of the first region is greater than the thickness h2 of the second region in the thickness direction of the solar cell; the first electrode is arranged on the side of the first region away from the first tunneling oxide layer and is in ohmic contact with the first region; and the first transparent conductive layer is arranged on the side of the second region away from the first tunneling oxide layer. In use, the back surface of the cell reduces most of the parasitic light absorption, the passivation quality is improved, the contact resistance of the thicker polysilicon layer in the grid line region can also be improved, and finally the photoelectric conversion effect of the cell is better.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to solar cells. Background Technology

[0002] With the development of modern industry, the global energy crisis and air pollution problems are becoming increasingly prominent, and traditional fuel energy is dwindling day by day. Since abundant solar radiation is an important renewable energy source, solar cells, with their ability to convert solar radiation into electricity, have become a focus of attention. However, in related technologies, solar cells suffer from significant parasitic light absorption, leading to additional heat generation and affecting the cell's temperature and voltage, ultimately resulting in lower cell efficiency. Utility Model Content

[0003] Therefore, it is necessary to provide a solar cell that addresses the problem of solar cells generating additional heat due to parasitic light absorption, which in turn affects the cell's temperature and voltage, ultimately resulting in lower cell efficiency.

[0004] A solar cell comprising:

[0005] A silicon substrate having a first surface, the first surface being the backlight surface of the solar cell;

[0006] A first tunneling oxide layer is disposed on the first surface;

[0007] A first polycrystalline silicon layer is disposed on the side of the first tunneling oxide layer opposite to the first surface; the first polycrystalline silicon layer includes a first region and a second region; along the thickness direction of the solar cell, the thickness h1 of the first region is greater than the thickness h2 of the second region.

[0008] A first electrode is disposed on a side opposite to the first tunneling oxide layer of the first region and is in ohmic contact with the first region.

[0009] A first transparent conductive layer is disposed in the second region on the side opposite to the first tunneling oxide layer.

[0010] In some embodiments, the thickness h2 of the second region along the thickness direction of the solar cell satisfies the condition:

[0011] 10nm≤h2≤20nm.

[0012] In some embodiments, the thickness h1 of the first region along the thickness direction of the solar cell satisfies the following condition:

[0013] 90nm≤h1≤150nm.

[0014] In some embodiments, the thickness h3 of the first transparent conductive layer along the thickness direction of the solar cell satisfies the following condition:

[0015] 70nm≤h3≤130nm.

[0016] In some embodiments, the thickness h4 of the first tunneling oxide layer along the thickness direction of the solar cell satisfies the following condition:

[0017] 1nm≤h4≤2nm.

[0018] In some embodiments, the solar cell further includes a first passivation antireflection layer;

[0019] The first passivation antireflection layer is disposed on the side of the first transparent conductive layer opposite to the second region.

[0020] In some embodiments, the silicon substrate further has a second surface, which is disposed opposite to the first surface, and the second surface serves as the light-receiving surface of the solar cell; the solar cell further includes:

[0021] A second tunneling oxide layer is disposed on the second surface;

[0022] A second polycrystalline silicon layer is disposed on the side of the second tunneling oxide layer opposite to the second surface; the second polycrystalline silicon layer includes a third region and a fourth region; along the thickness direction of the solar cell, the thickness h5 of the third region is greater than the thickness h6 of the fourth region;

[0023] The second electrode is disposed on the side of the third region away from the second tunneling oxide layer;

[0024] A second transparent conductive layer is disposed on the side of the fourth region away from the second tunneling oxide layer and is in ohmic contact with the third region.

[0025] In some embodiments, the thickness h6 of the fourth region along the thickness direction of the solar cell satisfies the following condition:

[0026] 10nm≤h6≤20nm.

[0027] In some embodiments, the thickness h7 of the second transparent conductive layer along the thickness direction of the solar cell satisfies the following condition:

[0028] 70nm≤h7≤130nm.

[0029] When the aforementioned solar cell is used, the first polycrystalline silicon layer is divided into a first region and a second region on the back surface of the solar cell, and the first and second regions have different thicknesses. The first electrode is placed on the side of the thicker first region, while the first transparent conductive layer is placed on the thinner second region. This results in a thicker polycrystalline silicon layer in the grid region of the first electrode on the back surface of the solar cell, while the polycrystalline silicon layer in the non-grid region is thinned, and a transparent conductive layer structure is placed in the non-grid region. This not only reduces most of the parasitic light absorption on the back surface of the solar cell, resulting in less additional heat generation and less impact on the cell's temperature and voltage, but also improves passivation quality. Furthermore, the contact resistance of the thicker polycrystalline silicon layer in the grid region is improved, ultimately leading to higher photoelectric conversion efficiency of the cell. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the film structure of a solar cell provided in some embodiments of this application.

[0031] Figure 2 for Figure 1 A schematic diagram of the silicon substrate in a solar cell is shown.

[0032] Figure 3 for Figure 1 The diagram shows a silicon substrate, a first tunneling oxide layer, a first polycrystalline silicon layer, and a first electrode in a solar cell.

[0033] Figure 4 for Figure 1 The diagram shows a silicon substrate, a first tunneling oxide layer, a first polycrystalline silicon layer, a first electrode, and a first transparent conductive layer in a solar cell.

[0034] Figure 5 for Figure 1 The diagram shows a silicon substrate, a second tunneling oxide layer, a second polycrystalline silicon layer, and a second electrode in a solar cell.

[0035] Figure 6 for Figure 1 The diagram shows a silicon substrate, a second tunneling oxide layer, a second polycrystalline silicon layer, a second electrode, and a second transparent conductive layer in a solar cell.

[0036] Reference numerals: 100-Silicon substrate; 110-First surface; 120-Second surface; 200-First tunneling oxide layer; 300-First polysilicon layer; 310-First region; 320-Second region; 400-First electrode; 500-First transparent conductive layer; 600-First passivation antireflection layer; 700-Second tunneling oxide layer; 800-Second polysilicon layer; 810-Third region; 820-Fourth region; 900-Second electrode; 1000-Second transparent conductive layer; 1100-Alumina layer; 1200-Second passivation antireflection layer. Detailed Implementation

[0037] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0038] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0039] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0040] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0041] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0042] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0043] See Figure 1 and Figure 4 , Figure 1 A schematic diagram of the film structure of a solar cell provided in some embodiments of this application is shown. Figure 4 It shows Figure 1The diagram shows a silicon substrate 100, a first tunneling oxide layer 200, a first polycrystalline silicon layer 300, a first electrode 400, and a first transparent conductive layer 500 in a solar cell. An embodiment of this application provides a solar cell comprising a silicon substrate 100, a first tunneling oxide layer 200, a first polycrystalline silicon layer 300, a first electrode 400, and a first transparent conductive layer 500. The silicon substrate 100 has a first surface 110, which is the backlight surface of the solar cell; the first tunneling oxide layer 200 is disposed on the first surface 110; the first polycrystalline silicon layer 300 is disposed on the side of the first tunneling oxide layer 200 facing away from the first surface 110; the first polycrystalline silicon layer 300 includes a first region 310 and a second region 320; along the thickness direction of the solar cell, the thickness h1 of the first region 310 is greater than the thickness h2 of the second region 320; specifically, the thickness direction of the solar cell is... Figure 1 The first electrode 400 is disposed on the side of the first region 310 away from the first tunneling oxide layer 200 and is in ohmic contact with the first region 310; the first transparent conductive layer 500 is disposed on the side of the second region 320 away from the first tunneling oxide layer 200.

[0044] When the aforementioned solar cell is used, the first polycrystalline silicon layer 300 is divided into a first region 310 and a second region 320 on the back surface of the solar cell, and the first region 310 and the second region 320 have different thicknesses. The first electrode 400 is disposed on the side of the thicker first region 310, while the first transparent conductive layer 500 is disposed on the thinner second region 320. This results in a thicker polycrystalline silicon layer in the grid region of the first electrode 400 that makes ohmic contact with the back surface of the solar cell, while the polycrystalline silicon layer in the non-grid region is thinned. The transparent conductive layer structure is then placed in the non-grid region. This not only reduces most of the parasitic light absorption on the back surface of the solar cell, resulting in less additional heat generation and less impact on the cell's temperature and voltage, but also improves passivation quality. Furthermore, the contact resistance of the thicker polycrystalline silicon layer in the grid region is improved, ultimately leading to better photoelectric conversion efficiency.

[0045] It should be noted that the first tunneling oxide layer 200 can be a silicon oxide layer. The first polycrystalline silicon layer 300 is a phosphorus-doped polycrystalline silicon layer. The first electrode 400 can be prepared using aluminum paste, silver paste, or silver-aluminum paste.

[0046] The structure of a solar cell is described in detail below. Please refer to [link / reference]. Figure 2 , Figure 3 , Figure 5 and Figure 6 , Figure 2 It shows Figure 1 A schematic diagram of the silicon substrate 100 in the solar cell shown. Figure 3 It shows Figure 1 The diagram shows a silicon substrate 100, a first tunneling oxide layer 200, a first polycrystalline silicon layer 300, and a first electrode 400 in a solar cell. Figure 5 It shows Figure 1 The diagram shows a silicon substrate 100, a second tunneling oxide layer 700, a second polycrystalline silicon layer 800, and a second electrode 900 in a solar cell. Figure 6 It shows Figure 1 The diagram shows a silicon substrate 100, a second tunneling oxide layer 700, a second polycrystalline silicon layer 800, a second electrode 900, and a second transparent conductive layer 1000 in a solar cell.

[0047] Please see Figure 3 In some embodiments, the thickness h2 of the second region 320 along the thickness direction of the solar cell satisfies the condition: 10nm ≤ h2 ≤ 20nm. By setting the thickness h2 of the second region 320 to be greater than or equal to 10nm and less than or equal to 20nm, the thickness of the polycrystalline silicon layer in the non-gateline region of the solar cell back surface is thinner, thereby effectively reducing parasitic absorption. In one specific embodiment, the thickness h2 of the second region 320 is 10nm. In another specific embodiment, the thickness h2 of the second region 320 is 20nm. In yet another specific embodiment, the thickness h2 of the second region 320 is 15nm.

[0048] Please see Figure 3 In some embodiments, the thickness h1 of the first region 310 along the thickness direction of the solar cell satisfies the condition: 90nm ≤ h1 ≤ 150nm. By setting the thickness of the first region 310 to be greater than or equal to 90nm and less than or equal to 150nm, the thickness of the polycrystalline silicon layer in the grid line region of the solar cell backlight surface is relatively thick, thereby resulting in better passivation of the solar cell backlight surface, a larger open-circuit voltage of the cell, and improved photoelectric conversion efficiency of the solar cell. In one specific embodiment, the thickness h1 of the first region 310 is 90nm. In another specific embodiment, the thickness h1 of the first region 310 is 150nm. In yet another specific embodiment, the thickness h1 of the first region 310 is 100nm.

[0049] Please see Figure 4In some embodiments, the thickness h3 of the first transparent conductive layer 500 along the thickness direction of the solar cell satisfies the condition: 70nm ≤ h3 ≤ 130nm. By setting the thickness h3 of the first transparent conductive layer 500 to be greater than or equal to 70nm and less than or equal to 130nm, the current generated by the cell is better collected and transmitted to the first electrode 400, thereby improving the photoelectric conversion efficiency of the solar cell. In one specific embodiment, the thickness h3 of the first transparent conductive layer 500 is 70nm. In another specific embodiment, the thickness h3 of the first transparent conductive layer 500 is 150nm. In yet another specific embodiment, the thickness h3 of the first transparent conductive layer 500 is 120nm.

[0050] Please see Figure 4 In some embodiments, the thickness h4 of the first tunneling oxide layer 200 along the thickness direction of the solar cell satisfies the condition: 1nm ≤ h4 ≤ 2nm. By setting the first tunneling oxide layer 200 to a relatively thin range of greater than 1nm and less than 2nm, this tunnel oxide passivating contact cell not only reduces optical loss, optimizes passivation effect, reduces cost, and improves process compatibility, but also promotes carrier tunneling.

[0051] Please see Figure 1 In some embodiments, the solar cell further includes a first passivation antireflection layer 600; the first passivation antireflection layer 600 is disposed on the side of the first transparent conductive layer 500 facing away from the second region 320. By providing the first passivation antireflection layer 600, the reflection of incident light on the back surface of the solar cell is reduced, increasing light transmittance; improving carrier collection efficiency; isolating moisture, oxygen, and other pollutants in the air; and, due to its own material refractive index, guiding light to undergo multiple reflections inside the cell, extending the optical path, ultimately playing the roles of antireflection, passivation, protection, and promoting light absorption. Specifically, the first passivation antireflection layer 600 can be made of silicon nitride.

[0052] Please see Figure 1 and Figure 6 In some embodiments, the silicon substrate 100 further has a second surface 120, which is disposed opposite to the first surface 110, and the second surface 120 is the light-receiving surface of the solar cell. Figure 2(As shown in the diagram), the solar cell also includes a second tunneling oxide layer 700, a second polycrystalline silicon layer 800, a second electrode 900, and a second transparent conductive layer 1000. The second tunneling oxide layer 700 is disposed on the second surface 120; the second polycrystalline silicon layer 800 is disposed on the side of the second tunneling oxide layer 700 away from the second surface 120; the second polycrystalline silicon layer 800 includes a third region 810 and a fourth region 820; along the thickness direction of the solar cell, the thickness h5 of the third region 810 is greater than the thickness h6 of the fourth region 820; the second electrode 900 is disposed on the side of the third region 810 away from the second tunneling oxide layer 700 and is in ohmic contact with the third region 810; the second transparent conductive layer 1000 is disposed on the side of the fourth region 820 away from the second tunneling oxide layer 700.

[0053] By dividing the second polycrystalline silicon layer 800 of the light-receiving surface of the solar cell into a third region 810 and a fourth region with different thicknesses, and placing the second electrode 900 on one side of the thicker third region 810, while placing the second transparent conductive layer 1000 on the thinner fourth region 820, the polycrystalline silicon layer in the grid region of the second electrode 900 in ohmic contact with the light-receiving surface of the solar cell is thicker, while the polycrystalline silicon layer in the non-grid region is thinned, and a transparent conductive layer structure is placed in the non-grid region. This not only reduces most of the parasitic light absorption on the light-receiving surface of the solar cell, resulting in less additional heat generation and less impact on the cell's temperature and voltage, but also improves passivation quality. Furthermore, the contact resistance of the thicker polycrystalline silicon layer in the grid region is improved, ultimately leading to higher cell efficiency and better photoelectric conversion performance.

[0054] It should be noted that the second tunneling oxide layer 700 can be a silicon oxide layer. The second polycrystalline silicon layer 800 is a phosphorus-doped polycrystalline silicon layer. The second electrode 900 can be prepared using aluminum paste, silver paste, or silver-aluminum paste.

[0055] Please see Figure 5 In some embodiments, the thickness h6 of the fourth region 820 along the thickness direction of the solar cell satisfies the condition: 10nm ≤ h6 ≤ 20nm. By setting the thickness h6 of the fourth region 820 to be greater than or equal to 10nm and less than or equal to 20nm, the thickness of the polycrystalline silicon layer in the non-gate region of the solar cell's light-receiving surface is made thinner, thereby effectively reducing parasitic absorption. In one specific embodiment, the thickness h6 of the fourth region 820 is 10nm. In another specific embodiment, the thickness h6 of the fourth region 820 is 20nm. In yet another specific embodiment, the thickness h6 of the fourth region 820 is 15nm.

[0056] Please see Figure 6In some embodiments, the thickness h7 of the second transparent conductive layer 1000 along the thickness direction of the solar cell satisfies the condition: 70nm ≤ h7 ≤ 130nm. By setting the thickness h7 of the second transparent conductive layer 1000 to be greater than or equal to 70nm and less than or equal to 130nm, the current generated by the cell is better collected and transmitted to the second electrode 900, thereby improving the photoelectric conversion efficiency of the solar cell. In one specific embodiment, the thickness h7 of the second transparent conductive layer 1000 is 70nm. In another specific embodiment, the thickness h7 of the second transparent conductive layer 1000 is 150nm. In yet another specific embodiment, the thickness h7 of the second transparent conductive layer 1000 is 120nm.

[0057] Please see Figure 1 In some embodiments, the solar cell further includes an aluminum oxide layer 1100 and a second passivation antireflection layer 1200; the aluminum oxide layer 1100 is disposed on the side of the second transparent conductive layer 1000 opposite to the fourth region 820. The second passivation antireflection layer 1200 is disposed on the side of the aluminum oxide layer 1100 opposite to the second transparent conductive layer 1000. The aluminum oxide layer 1100 is used to passivate, manage, and protect the light-receiving surface of the solar cell. Simultaneously, the second passivation antireflection layer 1200 reduces the reflection of incident light on the light-receiving surface of the solar cell, increasing light transmittance; improving carrier collection efficiency; and isolating moisture, oxygen, and other contaminants in the air. Furthermore, due to its own material refractive index, it guides light to undergo multiple reflections within the cell, extending the optical path, ultimately achieving the functions of antireflection, passivation, protection, and promoting light absorption. Specifically, the second passivation antireflection layer 1200 can be made of silicon nitride.

[0058] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A solar cell, characterized in that, The solar cell includes: A silicon substrate (100) having a first surface (110) which is the backlight surface of the solar cell; A first tunneling oxide layer (200) is disposed on the first surface (110). A first polycrystalline silicon layer (300) is disposed on the side of the first tunneling oxide layer (200) facing away from the first surface (110); the first polycrystalline silicon layer (300) includes a first region (310) and a second region (320); along the thickness direction of the solar cell, the thickness h1 of the first region (310) is greater than the thickness h2 of the second region (320); The first electrode (400) is disposed on the side of the first region (310) away from the first tunneling oxide layer (200) and is in ohmic contact with the first region (310); A first transparent conductive layer (500) is disposed on the side of the second region (320) opposite to the first tunneling oxide layer (200).

2. The solar cell according to claim 1, characterized in that, Along the thickness direction of the solar cell, the thickness of the second region (320) satisfies the following condition: 10nm≤h2≤20nm.

3. The solar cell according to claim 1, characterized in that, Along the thickness direction of the solar cell, the thickness h1 of the first region (310) satisfies the following condition: 90nm≤h1≤150nm.

4. The solar cell according to claim 1, characterized in that, Along the thickness direction of the solar cell, the thickness h3 of the first transparent conductive layer (500) satisfies the following condition: 70nm≤h3≤130nm.

5. The solar cell according to claim 1, characterized in that, Along the thickness direction of the solar cell, the thickness h4 of the first tunneling oxide layer (200) satisfies the following condition: 1nm≤h4≤2nm.

6. The solar cell according to claim 1, characterized in that, The solar cell also includes a first passivation antireflection layer (600). The first passivation antireflection layer (600) is disposed on the side of the first transparent conductive layer (500) away from the second region (320).

7. The solar cell according to any one of claims 1-6, characterized in that, The silicon substrate (100) further has a second surface (120), which is disposed opposite to the first surface (110), and the second surface (120) is the light-receiving surface of the solar cell; the solar cell further includes: The second tunneling oxide layer (700) is disposed on the second surface (120); A second polycrystalline silicon layer (800) is disposed on the side of the second tunneling oxide layer (700) facing away from the second surface (120); the second polycrystalline silicon layer (800) includes a third region (810) and a fourth region (820); along the thickness direction of the solar cell, the thickness h5 of the third region (810) is greater than the thickness h6 of the fourth region (820); The second electrode (900) is disposed on the side of the third region (810) away from the second tunneling oxide layer (700) and is in ohmic contact with the third region (810); A second transparent conductive layer (1000) is disposed on the side of the fourth region (820) opposite to the second tunneling oxide layer (700).

8. The solar cell according to claim 7, characterized in that, Along the thickness direction of the solar cell, the thickness h6 of the fourth region satisfies the following condition: 10nm≤h6≤20nm.

9. The solar cell according to claim 7, characterized in that, Along the thickness direction of the solar cell, the thickness h7 of the second transparent conductive layer (1000) satisfies the following condition: 70nm≤h7≤130nm.

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