Back contact solar cell and solar cell module

Abstract

The utility model discloses a back contact solar cell, which comprises a silicon substrate, a first doped layer and a second doped layer are formed on the back surface of the silicon substrate, the conduction types of dopants of the first doped layer and the second doped layer are different, and the first doped layer and the second doped layer are separated from each other. The first doped layer is arranged on the silicon substrate, the second doped layers are distributed at intervals, a first tunneling layer is arranged between the silicon substrate and the first doped layer, second tunneling layers are arranged between the silicon substrate and the second doped layers, the first doped layer is in conductive connection with a first electrode, and each second doped layer is in conductive connection with a second electrode. The utility model also discloses a solar cell module formed by mutually connecting a plurality of back contact solar cells. According to the utility model, carrier recombination can be reduced, charge collection can be increased, shunting can be reduced, and the efficiency of the solar cell can be improved.

Description

Technical Field

[0001] This utility model relates to a back-contact solar cell and a solar cell module, belonging to the field of solar cell technology. Background Technology

[0002] Back-contact solar cells have broad application prospects due to their higher photoelectric conversion efficiency. A back-contact solar cell is a cell where both the emitter and base contact electrodes are placed on the back side of the cell (the non-light-receiving surface). Since the light-receiving surface of this cell has no metal electrodes to block it, this effectively increases the short-circuit current of the cell. However, how to further improve the efficiency of back-contact solar cells at a lower cost remains a problem for the industry to solve. Utility Model Content

[0003] In view of the shortcomings of the prior art, the present invention provides a back-contact solar cell and a solar cell module, with the aim of further improving the efficiency and reliability of back-contact solar cells.

[0004] The technical solution of this utility model is as follows: A back-contact solar cell includes a silicon substrate, on the back side of which a first doped layer and a second doped layer are formed. The dopants in the first doped layer and the second doped layer have different conductivity types and are separated from each other. There are multiple second doped layers that are spaced apart. A first tunneling layer is disposed between the silicon substrate and the first doped layer, and a second tunneling layer is disposed between the silicon substrate and the second doped layer. The first doped layer is electrically connected to a first electrode, and each of the second doped layers is electrically connected to a second electrode.

[0005] Furthermore, the silicon substrate and the second doped layer have the same conductivity type, and the area of ​​the second doped layer is smaller than the area of ​​the first doped layer.

[0006] Furthermore, the contact surface between the second tunneling layer and the silicon substrate is recessed on the back side of the silicon substrate.

[0007] Furthermore, the second doped layer comprises a plurality of parallel first rectangular segments or a plurality of first rectangular segments and second rectangular segments, wherein the second rectangular segments are perpendicular to and connected to the first rectangular segments, the width of the first rectangular segments is 50 to 1000 μm, and the width of the second rectangular segments is 50 to 1000 μm.

[0008] Furthermore, the width of the first rectangular segment is 100–500 μm, and the width of the second rectangular segment is 100–500 μm.

[0009] Furthermore, a first passivation layer is provided on the front side of the silicon substrate, and a second passivation layer is provided on the surfaces of the first doped layer and the second doped layer, as well as between the first doped layer and the second doped layer.

[0010] Another technical solution of this utility model is: a solar cell module, comprising multiple back-contact solar cells as described above, wherein the first electrodes of the back-contact solar cells are connected to each other by a first wire, and the second electrodes of the back-contact solar cells are connected to each other by a second wire.

[0011] Furthermore, the surface of the first conductor and / or the second conductor is provided with a low-temperature conductive coating, which is one of tin, lead, bismuth, silver, antimony, gallium, and copper coatings.

[0012] Compared with the prior art, the advantages of the technical solution provided by this utility model are as follows:

[0013] This invention, by respectively setting a first tunneling layer and a second tunneling layer between the first doped layer and the second doped layer and the silicon substrate, effectively reduces carrier recombination near the semiconductor material surface and enhances charge collection. The separation of the first and second doped layers effectively prevents potential current shunting. Therefore, the open-circuit voltage and fill factor of the solar cell increase, thereby improving the efficiency of the solar cell. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the back-contact solar cell structure in Example 1.

[0015] Figure 2 This is a schematic diagram of the back structure of the back contact solar cell in Example 1.

[0016] Figure 3 This is a schematic diagram of the connection structure when back-contact solar cells are used to form a solar cell module, as shown in Example 1.

[0017] Figure 4 is a schematic diagram of the back structure of the back contact solar cell in Example 2.

[0018] Figure 5 is a schematic diagram of the back structure of the back contact solar cell in Example 3.

[0019] Figure 6 Schematic diagram of the back structure of a back-contact solar cell in other embodiments Figure 1 .

[0020] Figure 7 Schematic diagram of the back structure of a back-contact solar cell in other embodiments Figure 2 .

[0021] Figure 8Schematic diagram of the back structure of a back-contact solar cell in other embodiments Figure 3 . Detailed Implementation

[0022] The present invention will be further described below with reference to the embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. After reading this description, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0023] Example 1, please refer to Figure 1 and Figure 2 As shown, the back-contact solar cell of this embodiment includes a silicon substrate 1, which can be monocrystalline silicon and has a dopant of a first conductivity type. For example, when the dopant of the first conductivity type is n-type, it can be phosphorus (P), arsenic (As), bismuth (Bi), antimony (Sb) or similar elements; when the dopant of the first conductivity type is p-type, it can be boron (B), aluminum (Al), gallium (Ga), indium (In) or similar elements.

[0024] A first doped layer 2 and a second doped layer 3 are formed on the back side of a silicon substrate 1. The dopants in the first doped layer 2 and the second doped layer 3 have different conductivity types and are separated from each other. There are multiple second doped layers 3, which are spaced apart. The silicon substrate 1 and the second doped layer 3 have dopants of the same conductivity type; in this embodiment, both are n-type dopants, while the dopant in the first doped layer 2 has a p-type conductivity. In other embodiments, the dopants in the silicon substrate 1 and the second doped layer 3 may have a p-type conductivity, while the dopant in the first doped layer 2 may have an n-type conductivity. A first tunneling layer 4 is disposed between the silicon substrate 1 and the first doped layer 2, and a second tunneling layer 5 is disposed between the silicon substrate 1 and the second doped layer 3.

[0025] The front surface of the silicon substrate 1 is textured to have an irregular structure, such as an upright pyramid or an inverted pyramid shape. As the surface roughness increases, the light reflection energy on the front surface of the silicon substrate 1 is reduced. Correspondingly, the amount of light reaching the tunnel junction formed by the silicon substrate 1 and the first doped layer 2 increases. A first passivation layer 6 is formed on the irregular textured surface of the silicon substrate 1. The first passivation layer 6 reduces the reflectivity of light incident on the front surface of the silicon substrate 1, resulting in an increase in the amount of light reaching the tunnel junction and improving the short-circuit current of the solar cell. Furthermore, the first passivation layer 6 also passivates defects present on the surface or inside, reducing minority carrier recombination and increasing the open-circuit voltage of the solar cell. The passivation antireflection layer can be a multilayer film selected from one or more combinations of silicon nitride, hydrogen-containing silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, MgF2, ZnS, TiO2, and CeO2.

[0026] The back surface of the silicon substrate 1 can be a smooth and flat surface with a lower surface roughness than the front surface, obtained through chemical polishing or similar methods. This helps to form a uniform, high-quality tunneling junction on the back surface of the silicon substrate 1. The first tunneling layer 4 and the second tunneling layer 5 improve the interface characteristics of the back surface of the silicon substrate 1 and enable the generated charge carriers to be effectively transferred through the tunneling effect. The first tunneling layer 4 and the second tunneling layer 5 can be supported by a variety of materials capable of enabling charge carrier tunneling, including oxides, nitrides, and conductive polymers. The first tunneling layer 4 and the second tunneling layer 5 can include different materials, thicknesses, and / or crystal structures. In the embodiments of this application, the second tunneling layer 5 is disposed closer to the substrate than the first tunneling layer 4, that is, the contact surface between the second tunneling layer 5 and the silicon substrate 1 is recessed into the back surface of the silicon substrate 1.

[0027] The first doped layer 2 and the second doped layer 3 are formed on the first tunneling layer 4 and the second tunneling layer 5 by doping amorphous silicon, microcrystalline silicon, or polycrystalline silicon with different conductivity types using various methods (e.g., LPCVD deposition, PECVD deposition, APCVD deposition, or printing). In this embodiment, the second doped layer 3 and the second tunneling layer 5 are circular in shape. It should be noted that the shapes of the second doped layer 3 and the second tunneling layer 5 can also be other planar shapes, such as elliptical, triangular, rectangular, or hexagonal, or other elongated shapes.

[0028] The diameter of the second doped layer 3 is 50–1000 μm. When the diameter is less than 50 μm, the electrical connection between the corresponding electrodes of the second doped layer 3 may fail. When the diameter exceeds 1000 μm, the area of ​​the first doped layer 2 is too small. Considering the connection with the electrodes and the area ratio, the diameter of the second doped layer 3 is selected to be 100–500 μm.

[0029] A second passivation layer 7 covers the surfaces of the first doped layer 2 and the second doped layer 3, as well as the space between the first doped layer 2 and the second doped layer 3, providing lateral insulation between the first doped layer 2 and the second doped layer 3. A first electrode 8 is disposed on the back contact solar cell, and the first electrode 8 passes through the second passivation layer 7 and is electrically connected to the first doped layer 2. A second electrode 9 passes through the second passivation layer 7 and is electrically connected to the second doped layer 3.

[0030] The first electrode 8 is configured according to the shape and structure of the first doped layer 2, including a first main gate 801 and a first sub-gate 802. The first main gate 801 and the first sub-gate 802 are arranged perpendicularly, with the first main gate 801 being thicker and the first sub-gate 802 being thinner. The second electrode 9 is similar to the first electrode 8, forming a second main gate 901 and a second sub-gate 902 that are perpendicular to each other. The second main gate 901 is thicker and the second sub-gate 902 is thinner. Multiple second doped layers 3 are connected through the second electrode 9. It should be noted that the specific shapes of the first electrode 8 and the second electrode 9 are not limited to the shapes in this embodiment.

[0031] like Figure 3 As shown, when multiple back-contact solar cells of this embodiment are connected to form a solar cell module, the first electrodes 8 of the multiple back-contact solar cells are connected by a first wire 10, and the second electrodes 9 of the multiple back-contact solar cells are connected by a second wire 11. The conductive connection between the first wire 10, the second wire 11 and the first electrodes 8 and the second electrodes 9 is a low-temperature connection. No solder paste or conductive adhesive is needed between the first wire 10, the second wire 11 and the first electrodes 8 and the second electrodes 9. The surface of the conductive wire has a low-temperature conductive coating, and the coating material includes one or more combinations of tin, lead, bismuth, silver, antimony, gallium, and copper. The connection between the first wire 10, the second wire 11 and the first electrodes 8 and the second electrodes 9 is completed by pressing them together at a temperature of 120-180°C and a pressure of 0.01-0.1 MPa for 5-30 minutes. The low-temperature connection results in less thermal deformation of the solar cells, reduces the likelihood of microcracks or fragmentation, and improves the reliability of the solar module.

[0032] Example 2, please refer to Figure 4 As shown, the difference between this embodiment and Embodiment 1 lies in the shape of the second doped layer 3 and the corresponding second tunneling layer 5. In this embodiment, the second doped layer 3 and the corresponding second tunneling layer 5 are configured as multiple single-row arranged first rectangular segments, the width of which is 50-1000 μm, preferably 100-500 μm. The corresponding first doped layer 2 is also spaced into elongated rectangular shapes by the second doped layer 3. Thus, the first electrode 8 corresponding to the first doped layer 2 is configured in a single straight line, and the first electrodes 8 on the multiple elongated rectangular first doped layers 2 are connected to each other. Similarly, the second electrode 9 corresponding to the second doped layer 3 is configured in a single straight line, and the second electrodes 9 on the multiple first rectangular segments of the second doped layer 3 are connected to each other.

[0033] Example 3, please refer to Figure 5As shown, the difference between this embodiment and Embodiment 1 lies in the shape settings of the second doping layer 3 and the corresponding second tunneling layer 5. In this embodiment, the second doping layer 3 and the corresponding second tunneling layer 5 are arranged as a plurality of first rectangular segments in a row-column matrix. The width of the first rectangular segment is 50 - 1000 μm, preferably 100 - 500 μm. The first electrode 8 corresponding to the first doping layer 2 can adopt a main gate and sub-gate structure similar to that in Embodiment 1, while the second electrode 9 corresponding to the second doping layer 3 is configured in a single straight line form. The second electrodes 9 on the second doping layer 3 in the shape of a plurality of first rectangular segments are then connected to each other through vertical connecting electrodes 9a.

[0034] In some other embodiments, the second doping layer 3 and the corresponding second tunneling layer 5 can also be arranged as a plurality of first rectangular segments arranged in a staggered parallel manner in rows and columns, as Figure 6 shown, or can be arranged to include a plurality of first rectangular segments a arranged in parallel and second rectangular segments b perpendicular to the first rectangular segments a connecting each first rectangular segment a to form a small unit, and a plurality of units are then arranged in a staggered and spaced manner, as Figure 7 shown to form a plurality of staggered C shapes, or as Figure 8 shown to form a plurality of staggered "king" characters.

Claims

1. A back-contact solar cell, comprising a silicon substrate, wherein a first doped layer and a second doped layer are formed on the back side of the silicon substrate, characterized in that, The first doped layer and the second doped layer have different conductivity types of dopants and are separated from each other. There are multiple second doped layers that are spaced apart. A first tunneling layer is disposed between the silicon substrate and the first doped layer, and a second tunneling layer is disposed between the silicon substrate and the second doped layer. The first doped layer is electrically connected to the first electrode, and each of the second doped layers is electrically connected to the second electrode.

2. The back-contact solar cell according to claim 1, characterized in that, The silicon substrate has the same conductivity type as the second doped layer, and the area of ​​the second doped layer is smaller than the area of ​​the first doped layer.

3. The back-contact solar cell according to claim 1, characterized in that, The contact surface between the second tunneling layer and the silicon substrate is recessed on the back side of the silicon substrate.

4. The back-contact solar cell according to claim 1, characterized in that, The second doped layer comprises a plurality of parallel first rectangular segments or a plurality of first rectangular segments and second rectangular segments, wherein the second rectangular segments are perpendicular to and connected to the first rectangular segments, the width of the first rectangular segments is 50 to 1000 μm, and the width of the second rectangular segments is 50 to 1000 μm.

5. The back-contact solar cell according to claim 4, characterized in that, The width of the first rectangular segment is 100–500 μm, and the width of the second rectangular segment is 100–500 μm.

6. The back-contact solar cell according to claim 1, characterized in that, The silicon substrate has a first passivation layer on its front side, and a second passivation layer is provided on the surfaces of the first and second doped layers and between the first and second doped layers.

7. A solar cell module, characterized in that, It includes multiple back-contact solar cells as described in any one of claims 1 to 6, wherein the first electrodes of the back-contact solar cells are connected to each other by a first wire, and the second electrodes of the back-contact solar cells are connected to each other by a second wire.

8. The solar cell module according to claim 7, characterized in that, The surface of the first conductor and / or the second conductor is provided with a low-temperature conductive coating, which is one of tin, lead, bismuth, silver, antimony, gallium, and copper coatings.

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