Back contact solar cell and cell assembly

Abstract

To provide a back contact solar cell and a cell assembly, which can achieve both the electrical performance and optical performance of solar cells and can further improve the short-circuit current, the open-circuit voltage and the photoelectric conversion efficiency of the solar cells.SOLUTION: The present application provides a back contact solar cell including: a substrate which has a substrate front surface and a substrate back surface opposite to each other and in which the substrate front surface is close to a main-light-receiving surface of the cell and the substrate back surface is close to a non-main-light-receiving surface of the cell; a P-type polarity region including a first doped semiconductor layer; an N-type polarity region including a second doped semiconductor layer in which a thickness along a normal direction of the cell is smaller than a thickness of the first doped semiconductor layer along the normal direction, the N-type polarity region and the P-type polarity region being alternately located on one side of the substrate back surface; and an isolation region, located between each two adjacent N-type polarity region and P-type polarity region. A back contact solar cell and a cell assembly provided by the present application can achieve both the electrical performance and optical performance of solar cells and can further improve the short-circuit current, the open-circuit voltage and the photoelectric conversion efficiency of the solar cells.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This application relates generally to the field of crystalline silicon solar cells, and more particularly to back-contact solar cells and cell assemblies. [Background technology]

[0002] As the photovoltaic industry continues to pursue efficiency improvement and cost reduction, traditional PERC (Passivated Emitter and Rear Cell) cells are approaching the theoretical limit of their conversion efficiency, leaving little room for cost reduction, but the market continues to pursue higher photovoltaic conversion efficiency. Therefore, the industry is eager to develop next-generation high-efficiency technologies, and the mainstream technologies currently being promoted include tunnel oxide passivation contact cells (TOPCon), heterojunction cells (HJT), and back contact cells (IBC).

[0003] The metal electrodes of the IBC battery are located on the back side of the battery, and there is no shielding of the metal electrodes on the front side, which improves the light utilization rate and has a higher short-circuit current. However, how to improve the details of the conventional back contact battery structure and further improve its photoelectric conversion efficiency is an important topic that is continuously being researched in the industry. Summary of the Invention [Problem to be solved by the invention]

[0004] The technical problem to be solved by the present application is to provide a back-contact solar cell and cell assembly that can balance the electrical and optical performance of the solar cell and further improve the short-circuit current, open-circuit voltage, and photoelectric conversion efficiency of the solar cell. [Means for solving the problem]

[0005] In order to solve the above technical problems, the present application provides a back-contact solar cell comprising: a substrate having opposing substrate front and back surfaces, the substrate front surface being closer to a primary light-receiving surface of a cell and the substrate back surface being closer to a non-primary light-receiving surface of the cell; a P-type polarity region including a first doped semiconductor layer; a second doped semiconductor layer having a thickness along a normal direction of the cell that is smaller than the thickness of the first doped semiconductor layer along the normal direction, the N-type polarity region being located on one side of the substrate back surface alternately with the P-type polarity region; and a separation region being located between each of two adjacent N-type polarity regions and the P-type polarity region.

[0006] Preferably, the doping type of the first doped semiconductor layer is P-type doped and the doping impurities include boron atoms and / or boron-containing compounds, and the doping type of the second doped semiconductor layer is N-type doped and the doping impurities include phosphorus atoms and / or phosphorus-containing compounds.

[0007] Preferably, the first doped semiconductor layer has a thickness in the range of 15 to 500 nm, and the second doped semiconductor layer has a thickness in the range of 10 to 400 nm.

[0008] Preferably, the thickness of the second doped semiconductor layer is 30 to 150 nm thinner than the thickness of the first doped semiconductor layer.

[0009] Preferably, when the conductivity type of the substrate and the conductivity type of the P-type polarity region are opposite, the width of the P-type polarity region along the extension direction of the cell perpendicular to the normal direction is greater than the width of an adjacent N-type polarity region along the extension direction, and when the conductivity type of the substrate and the conductivity type of the P-type polarity region are the same, the width of the N-type polarity region along the extension direction is greater than the width of an adjacent P-type polarity region along the extension direction.

[0010] Preferably, the width of the isolation region along the extension direction is smaller than the width of any one of the P-type polarity regions or any one of the N-type polarity regions along the extension direction.

[0011] Preferably, the substrate further includes a first substrate doped layer adjacent to the back surface of the substrate at a position corresponding to the P-type polarity region in the substrate.

[0012] Preferably, the P-type polarity region further includes a first doped oxide layer having a thickness in the range of 0.5 to 3 nm adjacent to one side of the first doped semiconductor layer closer to the back surface of the substrate.

[0013] Preferably, the P-type polarity region further comprises a first substrate doped layer adjacent to the back surface of the substrate, the first doped oxide layer adjacent to a side of the first substrate doped layer remote from the back surface of the substrate.

[0014] Preferably, the substrate further comprises a second substrate doped layer adjacent to the back surface of the substrate at a position corresponding to the N-type polarity region in the substrate.

[0015] Preferably, the N-type polarity region further comprises a second doped oxide layer having a thickness in the range of 0.5-3 nm adjacent to one side of the second doped semiconductor layer closer to the back surface of the substrate.

[0016] Preferably, the N-type polarity region further comprises a second substrate doped layer adjacent to the back surface of the substrate, the second doped oxide layer adjacent to a side of the second substrate doped layer remote from the back surface of the substrate.

[0017] Preferably, the N-type polarity region, the P-type polarity region, and the isolation region further include a back surface passivation layer located in the outermost layer farther from the back surface of the substrate. Preferably, the back surface passivation layer includes a dielectric layer made of one of aluminum oxide, silicon nitride, silicon nitride, and silicon oxide, or a laminated dielectric layer made of two or more of them.

[0018] Preferably, a first electrode and a second electrode are further provided, each located in the P-type polarity region and the N-type polarity region, and the first electrode and the second electrode penetrate the back surface passivation layer and contact the first doped semiconductor layer and the second doped semiconductor layer, respectively.

[0019] Preferably, the substrate further comprises a surface passivation layer located on one side of the front surface thereof, the surface passivation layer comprising a dielectric layer made of one of aluminum oxide, silicon nitride, silicon nitride, silicon oxide, magnesium fluoride, or a laminated dielectric layer made of two or more of these.

[0020] Preferably, the substrate further comprises a surface field adjacent to the substrate surface, the doping type of the surface field being the same as the doping type of the substrate, and the doping concentration of the surface field being higher than that of the substrate.

[0021] In order to solve the above technical problems, the present application provides a cell assembly including a plurality of the above-described back contact solar cells arranged in series and / or parallel.

[0022] Compared with existing technologies, the present application provides an IBC back contact solar cell that uses a feature layer with good passivation effect, and sets the different polarity regions on the back surface of the cell to specific differentiated widths and thicknesses. This back contact cell with improved structural details can achieve both electrical and optical performance of the solar cell, and further improve the short circuit current, open circuit voltage and photoelectric conversion efficiency of the solar cell.

[0023] The inclusion of the drawings is intended to provide a further understanding of the present application, and are incorporated into and constitute a part of this application, the drawings illustrate embodiments of the present application, and together with the specification serve to explain the principles of the present application. [Brief description of the drawings]

[0024] [Figure 1]FIG. 1 is a structural schematic diagram of a back contact solar cell in one embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] In order to more clearly describe the technical ideas of the embodiments of the present application, the drawings that need to be used in the description of the embodiments will be briefly described. Obviously, the drawings in the following description are only some examples or embodiments of the present application, and those skilled in the art can also apply the present application to other similar scenarios based on these drawings without paying progressive labor. Unless otherwise clear from the language environment or otherwise described, the same symbols in the drawings represent the same structures or operations.

[0026] As used herein and in the claims, unless the context expressly indicates otherwise, terms such as "a," "one," "a kind," and / or "the" specifically include the plural rather than the singular. In general, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, and do not constitute an exclusive list of those steps and elements, and a method or apparatus may include other steps or elements.

[0027] Unless otherwise illustrated, the relative arrangement of components and steps, mathematical expressions, and numerical values ​​described in these examples are not intended to limit the scope of the present application. At the same time, it should be understood that for ease of explanation, the dimensions of each part shown in the drawings are not drawn based on actual proportional relationships. Although techniques, methods, and devices known to those of ordinary skill in the art may not be discussed in detail, such techniques, methods, and devices should be considered as part of the specification, where appropriate. In all examples shown and discussed herein, any specific values ​​should be construed as merely illustrative, not limiting. Thus, other examples of the exemplary embodiments may have different values. Note that similar symbols and alphabets represent similar terms in the following figures, so that once a term is defined in one figure, it is not necessary to further discuss it in the following figures.

[0028] In the description of this application, the orientations or positional relationships indicated by directional terms, such as "front, back, top, bottom, left, right", "side, length, vertical, level", "ceiling, bottom", etc., are generally orientations or positional relationships based on the drawings, and are merely for the purpose of facilitating and simplifying the description of this application. In the absence of a description to the contrary, these directional terms do not indicate or imply that a specified device or element must have a particular orientation or be configured and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of this application. The directional terms "inside, outside" refer to the inside and outside of the contour of each part itself.

[0029] For ease of description, spatially relative terms such as "on," "above," "on top of," "above" and the like may be used herein to describe the spatial relationship of one device or feature to another device or feature as shown in the figures. It should be understood that the spatially relative terms are intended to include different orientations of the device during use or operation other than the orientation described in the figures. For example, a device in the figures may be described as being "above other devices or structures" or "on top of other devices or structures" when inverted, and then positioned as being "below other devices or structures" or "under other devices or structures." Thus, the exemplary term "above" can include two orientations, "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein may be interpreted appropriately.

[0030] In addition, the use of words such as "first" and "second" to limit the components is merely for the purpose of making it easier to distinguish the relevant components, and unless otherwise stated, the above words have no special meaning and cannot be understood as a limitation on the scope of protection of the present application. Furthermore, although the terms used in the present application are selected from known common terms, some terms mentioned in the specification of the present application may be selected by the applicant according to his or her judgment, and the detailed meanings thereof will be explained in the relevant parts described in this specification. Furthermore, it is required to understand the present application through the meaning contained in each term as well as the actual terms used.

[0031] The present application has proposed a structural schematic diagram of a back-contact solar cell 10 (hereinafter, abbreviated as cell 10) with reference to FIG. 1. Cell 10 may mainly include a substrate 101, a P-type polarity region 102, an N-type polarity region 103, and an isolation region 104. Specifically, substrate 101 has a substrate front surface 1011 and a substrate back surface 1012 facing each other, among which substrate front surface 1011 is closer to the main light-receiving surface of cell 10 (in FIG. 1, the light irradiation direction S suggests that the top surface of cell 10 is the main light-receiving surface when cell 10 is arranged according to FIG. 1). Specifically, substrate front surface 1011 is usually a pile structure including pyramid piles and / or corrosion pit piles. Correspondingly, substrate back surface 1012 is closer to the non-main light-receiving surface of cell 10, and may be a polished surface structure including, for example, a conventional alkaline polished surface.

[0032] Furthermore, the P-type polarity region 102 in this embodiment includes a first doped semiconductor layer 1021. In this embodiment, the thickness range of the first doped semiconductor layer 1021 is 15-500 nm, but it is preferable to set it freely according to the actual manufacturing situation, such as 150-250 nm, 250-350 nm, 350-450 nm, or 50-150 nm. The doping type of the first doped semiconductor layer 1021 is P-type doped, and the doping impurities include P-type doped polycrystalline silicon such as boron atoms and / or boron-containing compounds.

[0033] Thereon, the N-type polarity region 103 is provided with a second doped semiconductor layer 1031. Preferably, the thickness range of the second doped semiconductor layer 1031 in this embodiment is 10-400 nm, more preferably 100-200 nm, 200-300 nm, 300-400 nm, 40-140 nm. The doping type of the second doped semiconductor layer 1031 is N-type doping, and the doping impurities include phosphorus atoms and / or phosphorus-containing compounds.

[0034] Preferably, in several embodiments of the present application, including FIG. 1, the thickness of the second doped semiconductor layer 1031 is 30 to 150 nm thinner than the thickness of the first doped semiconductor layer 1021, with more preferred ranges of the thickness difference being 50 nm, 100 nm, or any value between 50 nm and 100 nm.

[0035] 1 shows only a part of the battery 10, it can be seen that in this embodiment, the N-type polarity regions 103 and the P-type polarity regions 102 are alternately positioned on one side of the back surface 1012 of the substrate, and one separation region 104 is provided between every two adjacent N-type polarity regions 103 and P-type polarity regions 102. Illustratively, the separation region 104 may be a pile and / or polished surface structure. Since the conductive polarity of the N-type polarity region 103 and the P-type polarity region 102 are opposite, the separation region 104 is provided between them to form an electrical connection between the positive and negative electrodes of the battery 10, thereby preventing a short circuit.

[0036] In this embodiment, the thickness of the second doped semiconductor layer 1031 along the normal direction x of the battery 10 is preferably smaller than the thickness of the first doped semiconductor layer 1021 along the normal direction. Specifically, since the P-type polarity region 102 is P-type doped, and the doped impurities include boron atoms and / or boron-containing compounds, the solid solubility of the doped impurities in silicon is low, and the difficulty of doping is high. Therefore, a thick doped layer is required to reduce the sheet resistance. On the other hand, the N-type polarity region 103 is N-type doped, and the difficulty of doping it is low, so that for the battery 10, based on the above technical considerations, it is preferable to reduce the thickness of the N-type polarity region 103 (especially the second doped semiconductor layer 1031 therein) to reduce the absorption loss of irradiated light and increase the short-circuit current and conversion efficiency. The design of battery 10 can reduce the light loss of battery 10 and increase the short circuit current and conversion efficiency, and the different thicknesses of first doped semiconductor layer 1021 in P-type polarity region 102 and second doped semiconductor layer 1031 in N-type polarity region 103 can balance the electrical and optical performance of battery 10.

[0037] More specifically, in the present application, the substrate 101 is not of only one conductivity type, and different widths of the rear polarity regions of the battery 10 are set according to different conductivity types of the substrate 101. In order to better understand the width setting method, the N-type polarity region 103, the separation region 104, and the P-type polarity region 102 arranged adjacently and sequentially on the rear surface of the battery 10 are regarded as one polarity region group. In this embodiment, when the conductivity type of the substrate 101 is opposite to that of the P-type polarity region 102, the width of the P-type polarity region 102 along the extension direction y direction of the battery 10 (perpendicular to the normal direction x direction) is preferably larger than the sum of the widths of one N-type polarity region 103 and one separation region 104 adjacent to the P-type polarity region 102 of the same polarity region group along the extension direction y direction, and FIG. 1 shows such a situation.

[0038] On the other hand, in some modified embodiments based on FIG. 1, when the conductivity type of the substrate 101 is the same as the conductivity type of the P-type polarity region 102, the width of the N-type polarity region 103 along the extension direction y is greater than the sum of the widths along the extension direction of one adjacent P-type polarity region 102 and one isolation region 104 of the same polarity region group.

[0039] Specifically, a PN junction is formed on the back surface of the cell 10 between the substrate 101 and an area of ​​polarity opposite to the conductivity type of the semiconductor substrate 101. By setting the width as described above, in the embodiment of the different substrate conductivity type, the proportion of the area of ​​the PN junction of the cell is larger than the area of ​​the non-PN junction, which is favorable for carrier separation and collection, and can improve the fill factor and conversion efficiency of the solar cell.

[0040] In this embodiment, the P-type polarity region 102 further includes a first doped oxide layer 1022 whose doping type is P-type doped and adjacent to one side of the first doped semiconductor layer 1021 closer to the substrate back surface 1012. The first doped oxide layer 1022 includes silicon oxide and aluminum oxide. The thickness range of the first doped oxide layer 1022 is 0.5 to 3 nm, and preferably 1 to 2 nm. Furthermore, the substrate 101 further includes a first substrate doped layer 1023 whose doping type is P-type and adjacent to the substrate back surface 1012 in the substrate 101 at a position corresponding to the P-type polarity region 102. In this embodiment, the first doped oxide layer 1022 is adjacent to one side of the substrate back surface 1012 located in the substrate 101, i.e., adjacent to the first substrate doped layer 1023.

[0041] On the other hand, referring to FIG. 1, the N-type polarity region 103 further includes a second doped oxide layer 1032 including silicon oxide and aluminum oxide, adjacent to one side of the second doped semiconductor layer 1031 closer to the substrate back surface 1012. Similarly, the thickness range of the second doped oxide layer 1032 is 0.5-3 nm, preferably 1-2 nm. The substrate 101 further includes a second substrate doped layer 1033, whose doping type is N-type and adjacent to the substrate back surface 1012 in the substrate 101, at a position corresponding to the N-type polarity region 103, and the second doped oxide layer 1032 is adjacent to one side of the substrate back surface 1012 located in the substrate 101, i.e., adjacent to the second substrate doped layer 1023.

[0042] Specifically, given that the doping types of the second doped semiconductor layer 1031 and the first doped semiconductor layer 1021 are opposite, the doping types of the second substrate doped layer 1033 and the first substrate doped layer 1023 are opposite, and the second doped oxide layer 1032 has a doping type opposite to that of the first doped oxide layer 1022 and is N-type doped comprising N-type doped polycrystalline silicon such as phosphorus atoms, phosphorus ions, and / or phosphorus-containing compounds.

[0043] Based on the above configuration, the battery 10 further includes a backside passivation layer 105 located on the outermost layer of the N-type polarity region 103, the P-type polarity region 102, and the separation region 104 on the backside surface 1012 of the substrate (see FIG. 1 , it may be understood that the backside passivation layer 105 extends continuously to form the outermost backside surface of the battery 10, and also constitutes the non-primary light-receiving surface of the battery). The backside passivation layer 105 includes a dielectric layer made of one of aluminum oxide, silicon nitride, silicon nitride, and silicon oxide, or a laminated dielectric layer made of two or more of them.

[0044] In contrast, the cell 10 further comprises a surface passivation layer 106 located on one side of the substrate front surface 1011, the surface passivation layer 106 comprising a dielectric layer made of one of aluminum oxide, silicon nitride, silicon nitride, silicon oxide, magnesium fluoride, or a stacked dielectric layer made of two or more of them.

[0045] In this embodiment, the battery 10 further includes a plurality of first electrodes 107 located in each of the P-type polarity regions 102. The first electrodes 107 penetrate the back surface passivation layer 105 in the P-type polarity regions and are in electrical contact with the first doped semiconductor layer 1021. Here, the material of the first electrodes 107 includes conductive metals such as silver, copper, and compounds thereof. Similarly, the battery 10 further includes a plurality of second electrodes 108 located in each of the N-type polarity regions 102. In the N-type polarity regions, the second electrodes 108 penetrate the back surface passivation layer 105 and are in electrical contact with the second doped semiconductor layer 1031. Wherein, the material of the second electrodes 108 also includes conductive metals such as silver, copper, and compounds thereof.

[0046] Optionally, the cell 10 further comprises a surface field 109 (FSF) adjacent to the substrate surface 1011 of the substrate 101, where the doping type of the surface field 109 is the same as that of the substrate 101, and the doping concentration of the surface field 109 is higher than that of the substrate 101. The thickness range of the surface field 109 is preferably 0.005-5um, and the sheet resistance is 10-10000ohm / sq. In this embodiment, having the surface field 109 to reduce carrier recombination further improves the open circuit voltage and conversion efficiency of the solar cell.

[0047] Based on the above description, another aspect of the present application further proposes a cell assembly comprising a plurality of back contact solar cells proposed by any of the embodiments of the present application, such as the back contact solar cell 10 shown in FIG. 1, in series and / or parallel.

[0048] The back contact solar cell and the cell assembly to which it is applied proposed in this application are designed by optimizing the length and width parameters of different polarity regions on the back surface structure of the back contact solar cell, thereby achieving both electrical and optical performance of the solar cell and further improving the short circuit current, open circuit voltage and photoelectric conversion efficiency of the solar cell.

[0049] Although the basic concept above has been described, it is clear to those skilled in the art that the above disclosure is merely an example and does not constitute a limitation on the present application. Although not explicitly described herein, those skilled in the art may make various modifications, improvements, and alterations to the present application. Since such modifications, improvements, and alterations are proposed in the present application, such modifications, improvements, and alterations still fall within the spirit and scope of the embodiments of the present application.

[0050] At the same time, certain terms are used herein to describe embodiments of the present application. For example, "an embodiment," "an embodiment," and / or "some embodiments" refer to features, structures, or characteristics associated with at least one embodiment of the present application. It should be emphasized and noted that "an embodiment" or "an embodiment" or "one alternative embodiment" referenced two or more times in different locations herein do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of the present application may be combined as appropriate.

[0051] For the same reason, in the foregoing description of the embodiments of the present application, multiple features may be grouped together in one embodiment, drawing, or description in order to simplify the expression of the disclosure of the present application and to facilitate the understanding of one or more embodiments of the present application. However, this method of disclosure does not imply that the subject matter of the present application requires more features than are recited in the claims. In reality, an embodiment may have fewer features than all the features of a single embodiment described above.

[0052] In some examples, numbers are used to describe the number of components, attributes, and the numbers used to describe such examples are to be understood as being modified in some examples using the modifiers "about", "approximately", or "approximately". Unless otherwise specified, "about", "approximately", or "approximately" means that the numbers are allowed to vary by ±20%. Correspondingly, in some examples, all numerical parameters used in the specification and claims are approximate, and these approximations may vary depending on the desired characteristics of the particular example. In some examples, the numerical parameters should be calculated using the number of significant digits given and common digit conservation methods. In some examples of the present application, the numerical ranges and parameters used to determine the breadth of the ranges are approximate, but in specific examples, such numerical values ​​are set as precisely as possible within the ranges possible.

[0053] Although the present application has been described with reference to the present specific embodiment, it should be recognized by those skilled in the art that the above embodiment is merely for the purpose of illustrating the present application, and various equivalent changes or substitutions can be made without departing from the spirit of the present application. Therefore, any changes or modifications of the above embodiment within the substantial spirit of the present application are included in the scope of the claims of the present application. [Explanation of symbols]

[0054] 10 Cells, Back Contact Solar Cells 101 Substrate 102 P-type polar region 103 N-type polar region 104 Separation area 105 Backside passivation layer 106 Surface passivation layer 107 First Electrode 108 Second Electrode 109 Surface Electric Field 1011 Board surface 1012 Back side of board 1021 First doped semiconductor layer 1022 First doped oxide layer 1023 First substrate doped layer 1031 Second doped semiconductor layer 1032 Second doped oxide layer 1033 Second substrate doped layer

Claims

1. a substrate having an opposing substrate front surface and a substrate back surface, the substrate front surface being closer to a primary light receiving surface of the cell and the substrate back surface being closer to a non-primary light receiving surface of the cell; a P-type polarity region including a first doped semiconductor layer; a second doped semiconductor layer having a thickness along a normal direction of the cell that is smaller than a thickness along the normal direction of the first doped semiconductor layer, and an N-type polarity region located on one side of the back surface of the substrate alternating with the P-type polarity region; an isolation region located between each of two adjacent N-type polarity regions and P-type polarity regions; A back contact solar cell comprising:

2. The doping type of the first doped semiconductor layer is P-type doping, and the doping impurities include boron atoms and / or boron-containing compounds; 10. The back contact solar cell of claim 1, wherein the doping type of the second doped semiconductor layer is N-type doping, and the doping impurities include phosphorus atoms and / or phosphorus-containing compounds.

3. 10. The back contact solar cell of claim 1 , wherein the first doped semiconductor layer has a thickness range of 15-500 nm and the second doped semiconductor layer has a thickness range of 10-400 nm.

4. 2. The back contact solar cell of claim 1 , wherein the thickness of the second doped semiconductor layer along the normal direction is 30 to 150 nm less than the thickness of the first doped semiconductor layer along the normal direction.

5. When the conductive type of the substrate and the conductive type of the P-type polarity region are opposite to each other, the width of the P-type polarity region along the extension direction of the cell perpendicular to the normal direction is greater than the width of an adjacent N-type polarity region along the extension direction; 5. The back contact solar cell of claim 1, wherein when the conductivity type of the substrate and the conductivity type of the P-type polarity region are the same, the width of the N-type polarity region along the extension direction is greater than the width of an adjacent P-type polarity region along the extension direction.

6. 6. The back contact solar cell of claim 5 , wherein the width of the isolation region along the extension direction is smaller than the width of any one of the P-type polarity regions or any one of the N-type polarity regions along the extension direction.

7. 5. The back contact solar cell of claim 1 , further comprising a first substrate doped layer adjacent to the back surface of the substrate at a position corresponding to the P-type polarity region in the substrate.

8. 5. The back contact solar cell of claim 1, wherein the P-type polarity region further comprises a first doped oxide layer having a thickness in the range of 0.5 to 3 nm and adjacent to one side of the first doped semiconductor layer closer to the back surface of the substrate.

9. 5. The back contact solar cell of claim 1 , further comprising a second substrate doped layer adjacent to the back surface of the substrate at a position corresponding to the N-type polarity region in the substrate.

10. 5. The back contact solar cell of claim 1, wherein the N-polarity region further comprises a second doped oxide layer having a thickness in the range of 0.5 to 3 nm and adjacent to a side of the second doped semiconductor layer closer to the back surface of the substrate.

11. 5. The back contact solar cell of claim 1 , further comprising a back surface passivation layer located in the outermost layer farther from the back surface of the substrate in the N-type polarity region, the P-type polarity region, and the isolation region.

12. 12. The back contact solar cell of claim 11 , wherein the rear surface passivation layer comprises a dielectric layer made of one of aluminum oxide, silicon nitride, silicon nitride, and silicon oxide, or a stacked dielectric layer made of two or more of these.

13. 13. The back contact solar cell of claim 12 further comprising a first electrode and a second electrode located in the P-type polarity region and the N-type polarity region, respectively, the first electrode and the second electrode penetrating the back surface passivation layer and contacting the first doped semiconductor layer and the second doped semiconductor layer, respectively.

14. 10. The back contact solar cell of claim 1 , further comprising a surface passivation layer located on one side of the front surface of the substrate, the surface passivation layer comprising a dielectric layer made of one of aluminum oxide, silicon nitride, silicon nitride, silicon oxide, magnesium fluoride, or a stacked dielectric layer made of two or more of these.

15. 15. The back contact solar cell of claim 1 or claim 14, further comprising a surface field in the substrate adjacent to the substrate surface, the doping type of the surface field being the same as the doping type of the substrate, and the doping concentration of the surface field being higher than that of the substrate.

16. 16. A cell assembly comprising a plurality of back contact solar cells according to any one of claims 1 to 15 arranged in series and / or parallel.

Images