Back contact solar cell, preparation method thereof and photovoltaic module

Abstract

The invention provides a back contact solar cell, a preparation method thereof and a photovoltaic module, and relates to the field of photovoltaic technology. The insulation structure in the back contact solar cell is at least located in a first transmission layer in a first lamination sub-region, and / or at least located between the first transmission layer and a second transmission layer in the first lamination sub-region; on one side close to the second conductive region in the first direction, the edge of the insulation structure is farther away from the second conductive region than the edge of the first transmission layer. In the process of forming the second transmission layer, the insulation structure does not affect the preparation of the second transmission layer, so that the coverage of the junction of the isolation region and the second conductive region and the coverage of the second transmission layer are relatively comprehensive, the film forming quality is relatively good, and the passivation effect of the junction of the isolation region and the second conductive region is relatively good; the passivation effect of the isolation area in the back contact solar cell is improved, and the power generation efficiency of the back contact solar cell can be improved.

Description

[0001] This application claims the priority of the Chinese patent application filed with the China Patent Office on September 30, 2024, with application number 202411388900.8 and titled “Back-contact solar cell, preparation method thereof and photovoltaic module”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the field of photovoltaic technology, and in particular to a back-contact solar cell and a preparation method thereof, and a photovoltaic module. Background Art

[0003] Back-contact solar cells can make full use of sunlight due to their structure without grid lines on the light-facing side, making them more efficient. In addition, due to their structure without grid lines on the light-facing side, the appearance of the component end is more beautiful, so they have broad application prospects.

[0004] The two conductive types of transport layers in the back-contact solar cell are located on the same side of the silicon substrate. Therefore, an isolation region is usually set between the two conductive regions to reduce the risk of leakage.

[0005] However, there is still a risk of leakage in the back-contact solar cell simply by setting up an isolation region. Moreover, the passivation effect of the isolation region in the existing back-contact solar cell is poor, which affects the power generation efficiency of the cell. Summary of the invention

[0006] The present invention provides a back-contact solar cell and a preparation method thereof and a photovoltaic module, aiming to solve the problem of poor positioning effect in existing back-contact solar cells.

[0007] A first aspect of the present invention provides a back-contact solar cell, comprising:

[0008] A silicon substrate; the silicon substrate comprises: a first surface and a second surface opposite to each other; the first surface comprises: a first conductive region, a second conductive region and an isolation region between the first conductive region and the second conductive region; the first conductive region, the isolation region and the second conductive region are sequentially distributed in a first direction; the isolation region comprises: a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region;

[0009] a first transmission layer, located on the first conductive region and the isolation region;

[0010] a second transmission layer, located at least on the second conductive region and the first stacked sub-region, and in the first stacked sub-region, the second transmission layer is located on a side of the first transmission layer away from the silicon substrate; the first transmission layer and the second transmission layer have different conductivity types;

[0011] An insulating structure is at least located in the first transmission layer within the first stacked sub-region, and / or between the first transmission layer and the second transmission layer within the first stacked sub-region; and on one side closer to the second conductive region in the first direction, the edge of the insulating structure is farther from the second conductive region than the edge of the first transmission layer.

[0012] A transparent conductive layer is located on the side of the first transmission layer and the second transmission layer facing away from the silicon substrate; the transparent conductive layer is disconnected in the opening sub-region.

[0013] In this application, firstly, an insulating structure is further provided in the isolation region, which further reduces the risk of leakage. Secondly, on one side closer to the second conductive region in the first direction, the edge of the insulating structure is farther from the second conductive region than the edge of the first transmission layer. The side closer to the second conductive region in the first direction is the junction between the second conductive region and the isolation region. On the side closer to the second conductive region in the first direction, the edge of the insulating structure does not protrude from the junction between the isolation region and the second conductive region. During the formation of the second transmission layer, the insulating structure does not affect the film formation of the second transmission layer, especially the passivation film layer, at the junction. The coverage of the second transmission layer is relatively comprehensive, and the film formation quality is good. The passivation effect at the junction between the isolation region and the second conductive region is good, which improves the passivation effect of the isolation region (junction) in the back-contact solar cell and can improve the power generation efficiency of the back-contact solar cell. That is to say, on one side closer to the second conductive region in the first direction, the edge of the insulating structure is farther from the second conductive region than the edge of the first transmission layer, that is, the insulating structure is retracted relative to the first transmission layer. In this way, the side wall of the insulating structure, the top surface of the first transmission layer, and the side wall of the first transmission layer form a retracted step; the structure of the step makes this area no longer "steep"; compared with the case where the insulating structure protrudes from the first transmission layer or the side wall of the insulating structure is flush with the side wall of the first transmission layer, when the second transmission layer covers this area, it is relatively flat, which is more conducive to the film formation of the second transmission layer, so that this area can be better passivated and the power generation efficiency can be improved.

[0014] Optionally, on the first surface, the projection of the insulating structure and the projection of the opening sub-region do not overlap.

[0015] Optionally, on the first surface, the projection of the opening sub-region is located within the projection of the insulating structure.

[0016] Optionally, on the first surface, the projection of the opening sub-region and the projection of the insulating structure only partially overlap.

[0017] Optionally, the material of the insulating structure is selected from at least one of silicon oxide, silicon nitride, and silicon oxynitride.

[0018] Optionally, the insulating structure contains doping elements, which may be provided by a doping source separately and enter the insulating structure, or may be diffused into the insulating structure by doping elements in the transmission layer or the silicon substrate.

[0019] Optionally, when the insulating structure is located in the first transmission layer in the first stacking sub-region, the thickness of the insulating structure is 0.1 nm-20 nm.

[0020] Optionally, the back-contact solar cell further comprises: a heat-affected structure, the heat-affected structure is located on a side of the insulating structure away from the silicon substrate, the heat-affected structure is in contact with the insulating structure, and in a thickness direction of the silicon substrate, a projection of the heat-affected structure falls within a projection of the insulating structure;

[0021] The second transmission layer includes a heat-affected structure and a non-heat-affected structure;

[0022] The electrical conductivity of the heat-affected structure is less than the electrical conductivity of the non-heat-affected structure.

[0023] Optionally, the first transmission layer includes: a stacked tunneling oxide layer and a doped polysilicon layer, the tunneling oxide layer is closer to the silicon substrate than the doped polycrystalline layer; the second transmission layer includes: a stacked intrinsic amorphous silicon layer and a doped amorphous silicon layer; the intrinsic amorphous silicon layer is closer to the silicon substrate; the doping types of the doped polycrystalline layer and the doped amorphous silicon layer are different; or,

[0024] The first transmission layer and the second transmission layer both include: a tunneling oxide layer and a doped polysilicon layer stacked, wherein the tunneling oxide layer in the first transmission layer and the second transmission layer is closer to the silicon substrate than the doped polysilicon layer; the doping types of the doped polysilicon layer in the first transmission layer and the second transmission layer are different; or

[0025] The first transmission layer and the second transmission layer both include: an intrinsic amorphous silicon layer and a doped amorphous silicon layer stacked together, wherein the intrinsic amorphous silicon layer in the first transmission layer and the second transmission layer is closer to the silicon substrate than the doped amorphous silicon layer; and the doping types of the doped amorphous layers in the first transmission layer and the second transmission layer are different.

[0026] Optionally, on a side close to the second conductive region in the first direction, a distance between an edge of the insulating structure and an edge of the first transmission layer is 5 nm to 50 μm.

[0027] Optionally, in the first direction, the width of the insulating structure is 10 nm to 100 μm.

[0028] Optionally, the isolation region is composed of a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region; the second transmission layer is at least located on the second conductive region and the first stacked sub-region; or,

[0029] The isolation region is composed of a first stacked sub-region adjacent to the second conductive region, an opening sub-region adjacent to the first stacked sub-region, and a second stacked sub-region adjacent to the first conductive region; the second transmission layer is at least located on the second conductive region, the first stacked sub-region, and the second stacked sub-region.

[0030] Optionally, the back-contact solar cell further includes:

[0031] A weather-resistant oxide layer filled on the underlying structure at the disconnection position of the transparent conductive layer; the mass ratio of oxygen atoms in the weather-resistant oxide layer is greater than or equal to 70%.

[0032] Optionally, the edge of the first transmission layer located in the first stacked sub-region contacts the edge of the second transmission layer located in the first stacked sub-region, and together with the transparent conductive layer, forms a thermal hotspot prevention structure.

[0033] Optionally, the insulating structure is at least located between the first transmission layer and the second transmission layer in the first stacked sub-region, and the thickness of the insulating structure is less than or equal to 150 nm.

[0034] Optionally, the insulating structure includes at least one of crystalline silicon, crystalline silicon nitride, and crystalline silicon oxynitride.

[0035] Optionally, the insulating structure further includes: a protruding portion whose projection on the first surface in the first direction is located outside the projection of the opening sub-region;

[0036] In the insulating structure, the portion whose projection on the first surface overlaps with the projection of the opening sub-region is the overlapping portion;

[0037] The structures of the protruding portion and the overlapping portion are different.

[0038] Optionally, the material properties of the protruding portion and the overlapping portion are different; and / or,

[0039] The thicknesses of the protruding portion and the overlapping portion are different.

[0040] Optionally, the insulating structure between the first and second conductive layers within the first stacked sub-region includes a silicon nitride layer and a silicate glass layer stacked together, with the silicate glass layer closer to the silicon substrate.

[0041] Optionally, along the thickness direction of the silicon substrate, the insulating structure includes a third region and a fourth region, with the third region closer to the silicon substrate than the fourth region;

[0042] The degree of crystallization of the fourth region is greater than that of the third region.

[0043] Optionally, along the thickness direction of the silicon substrate, the insulating structure includes a third region and a fourth region, with the third region closer to the silicon substrate than the fourth region;

[0044] The ratio of the number of silicon atoms to nitrogen atoms in the fourth region is greater than that in the third region.

[0045] In a second aspect of the present invention, a method for manufacturing a back-contact solar cell is provided, including:

[0046] Providing a silicon substrate; the silicon substrate includes opposite first and second surfaces; the first surface includes a first conductive region, a second conductive region, and an isolation region between the first and second conductive regions; the direction in which the first conductive region, the isolation region, and the second conductive region are sequentially arranged is the first direction; the isolation region includes a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region;

[0047] Forming a first conductive layer on the first conductive region and the isolation region;

[0048] Modifying at least the first conductive layer within the first stacked sub-region to convert at least the first conductive layer within the first stacked sub-region into an insulating structure; and / or forming an insulating structure on at least the first conductive layer within the first stacked sub-region; in the first direction, the insulating structure is farther from the second conductive region than the first conductive layer;

[0049] Forming at least a second conductive layer on the second conductive region and the first stacked sub-region; the second conductive layer is located on the side of the insulating structure away from the silicon substrate; the first and second conductive layers have different conductivity types;

[0050] Forming a transparent conductive layer on the sides of the first and second conductive layers away from the silicon substrate and disconnected in the opening sub-region.

[0051] Optionally, the forming of the first conductive layer includes:

[0052] Successively fabricating a whole layer of the first conductive layer and a mask layer on the first surface of the silicon substrate;

[0053] Irradiating the portion of the mask layer located on the second conductive region with a laser and performing wet processing to expose the second conductive region, and retaining the mask layer and the first conductive layer located on the first conductive region and the isolation region;

[0054] The forming of the insulating structure on at least the first conductive layer within the first stacked sub-region includes:

[0055] Irradiating the portion of the mask layer at least within the first stacked sub-region with a laser to modify at least the mask layer within the first stacked sub-region to obtain at least a partial insulating structure.

[0056] In a third aspect of the present invention, there is provided a photovoltaic module, including: a plurality of any one of the foregoing back-contact solar cells.

[0057] In a fourth aspect of the present invention, there is provided a method for manufacturing a back-contact solar cell, including:

[0058] Providing a silicon substrate; the silicon substrate includes: opposite first and second surfaces; the first surface includes: a first conductive region, a second conductive region, and an isolation region located between the first conductive region and the second conductive region; the direction in which the first conductive region, the isolation region, and the second conductive region are sequentially distributed is the first direction; the isolation region includes: a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region; forming a first conductive layer on the first conductive region and the isolation region;

[0059] Fabricating a second conductive layer on the second conductive region and the first conductive layer;

[0060] The first conductive layer and the second conductive layer have different conductivity types;

[0061] Irradiating the position of the second conductive layer within the isolation region with a laser so that the first conductive layer and the second conductive layer within a local position within the isolation region are co-doped to form an insulating structure; the width of the laser irradiation is less than or equal to the width of the isolation region; the direction in which the width is located is parallel to the first direction;

[0062] Forming a transparent conductive layer on the side of the first conductive layer and the second conductive layer facing away from the silicon substrate and disconnected in the opening sub-region.

[0063] The above-mentioned back-contact solar cell, its preparation method and photovoltaic module have the same or similar beneficial effects. To avoid repetition, they will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0065] Figures 1 to 12 FIG. shows a partial structural schematic diagram of 12 back-contact solar cells in the embodiments of the present invention;

[0066] Figure 13 FIG. shows a schematic diagram of a leakage channel in a back-contact solar cell;

[0067] Figure 14 FIG. shows a schematic diagram of blocking a leakage channel in a back-contact solar cell in the embodiments of the present invention.

[0068] Description of the drawing reference numerals:

[0069] 1 - silicon substrate, 2 - insulating structure, 3 - transparent conductive layer, 4 - tunneling oxide layer, 5 - doped polysilicon layer, 6 - intrinsic amorphous silicon layer, 7 - doped amorphous silicon layer, 8 - first electrode, 9 - second electrode, 10 - thermal influence structure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0070] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0071] The present invention provides a back-contact solar cell. Referring to Figures 1 to 14 , the back-contact solar cell includes: a silicon substrate 1, a first transmission layer, a second transmission layer, an insulating structure 2, and a transparent conductive layer 3.

[0072] The silicon substrate 1 includes: a first surface and a second surface opposite to each other. The first surface can be its backlight surface, and the second surface is the light-facing surface. During the normal operation of the back-contact solar cell, the surface of the silicon substrate 1 that mainly absorbs light is the light-facing surface. Figures 1 to 14The upper surfaces of the middle silicon substrate 1 are all its first surfaces, and the lower surfaces are all its second surfaces. The first surface includes: a first conductive region, a second conductive region, and an isolation region located between the first conductive region and the second conductive region. As Figures 1 to 12 In the first surface of, the region between the dashed line L1 and the dashed line L2 is the first conductive region, the region between the dashed line L2 and the dashed line L3 is the isolation region, and the region between the dashed line L3 and the dashed line L4 is the second conductive region. The direction in which the first conductive region, the isolation region, and the second conductive region are sequentially distributed on the first surface is the first direction M. The isolation region includes: a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region. As Figure 1 , Figure 2 , Figure 4 In, the isolation region between the dashed line L2 and the dashed line L3 in the first surface includes: a first stacked sub-region between the dashed line L3 and the dashed line L5, and an opening sub-region between the dashed line L2 and the dashed line L5, where the first stacked sub-region is adjacent to the second conductive region, and the opening sub-region is adjacent to the first stacked sub-region. Or, as Figure 3 , Figure 5 , to Figure 12 In, the isolation region between the dashed line L2 and the dashed line L3 in the first surface includes: a first stacked sub-region between the dashed line L3 and the dashed line L5, and an opening sub-region between the dashed line L5 and the dashed line L7, where the first stacked sub-region is adjacent to the second conductive region, and the opening sub-region is adjacent to the first stacked sub-region.

[0073] A first transmission layer, located on the first conductive region and the isolation region, that is, the first transmission layer is located in the region of the first surface between the dashed line L1 and the dashed line L3. A second transmission layer, at least located on the second conductive region and the first stacked sub-region, and in the first stacked sub-region, the second transmission layer is located on the side of the first transmission layer away from the silicon substrate 1, that is, the second transmission layer is at least located in the region of the first surface between the dashed line L4 and the dashed line L5, and in the region between the dashed line L5 and the dashed line L3, the second transmission layer is farther from the silicon substrate than the first transmission layer. The conductive types of the first transmission layer and the second transmission layer are different, and one of them is an N-type transmission layer and the other is a P-type transmission layer.

[0074] It should be noted that the dashed lines L1 to L7 mentioned throughout this application and in the drawings are only for distinguishing different regions and do not exist in the actual back-contact solar cell.

[0075] The insulating structure 2 is at least in the first transmission layer within the first stacked sub-region, and / or, the insulating structure 2 is at least between the first transmission layer and the second transmission layer within the first stacked sub-region. That is to say, the insulating structure 2 does not protrude from the first transmission layer, at least in the first transmission layer between the dashed line L5 and the dashed line L3, and / or, the insulating structure 2 is an independent layer, at least between the first transmission layer and the second transmission layer between the dashed line L5 and the dashed line L3. For example, referring to Figure 2 , Figure 3 , Figure 8 , Figure 10 , Figure 11 and Figure 12 , the insulating structure 2 is at least in the first transmission layer within the first stacked sub-region. For another example, referring to Figure 1 , Figures 4 to 7 , Figure 9 , the insulating structure 2 is at least between the first transmission layer and the second transmission layer within the first stacked sub-region. For another example, the insulating structure 2 is at least in the first transmission layer within the first stacked sub-region, and the insulating structure 2 is at least between the first transmission layer and the second transmission layer within the first stacked sub-region. By providing the insulating structure 2 in this isolation region, the short-circuit risk or leakage risk within the back-contact solar cell can be further reduced.

[0076] On the side closer to the second conductive region in the first direction M, the edge of the insulating structure 2 is farther from the second conductive region than the edge of the first transmission layer. The edge of the insulating structure 2 can be the contour line or end of the insulating structure, such as Figures 1 to 12Among them, on one side of the insulating structure 2 close to the second conductive region in the first direction M, the edge of the insulating structure 2 can coincide with the dotted line L6, and on one side of the first transmission layer close to the second conductive region in the first direction M, the edge of the first transmission layer can coincide with the dotted line L3. Specifically, on one side of the insulating structure 2 close to the second conductive region in the first direction M, if the edge of the insulating structure 2 protrudes from the junction of the isolation region and the second conductive region, and if the protruding part of the insulating structure 2 is not cleaned and the second transmission layer is continuously disposed thereon, due to the shielding of the insulating structure 2 at the junction, the second transmission layer cannot be disposed at the junction, resulting in almost no passivation layer covering the junction, greatly reducing the passivation effect at the junction and seriously affecting the power generation efficiency of the back contact solar cell. To solve the above technical problems, in the present application, on one side of the insulating structure 2 close to the second conductive region in the first direction M, the edge of the insulating structure 2 is farther from the second conductive region than the edge of the first transmission layer. On one side of the first direction close to the second conductive region, that is, the junction of the second conductive region and the isolation region. On one side of the insulating structure 2 close to the second conductive region in the first direction M, the edge of the insulating structure 2 does not protrude from the junction of the isolation region and the second conductive region. During the formation of the second transmission layer, the insulating structure does not affect the film formation of the second transmission layer, especially the passivation film layer, at the junction, so that the second transmission layer can better cover the first transmission layer, that is, at the junction of the isolation region and the second conductive region, the coverage of the second transmission layer is relatively comprehensive, and a similar stepped structure is formed at the junction, which is more conducive to the second transmission layer better covering the junction, that is, the film formation quality of the second transmission layer is good, the passivation effect at the junction of the isolation region and the second conductive region is good, the number of defects on the backlight side of the back contact solar cell can be reduced, especially the number of defects at the junction of the isolation region and the second conductive region in the back contact solar cell is reduced, the carrier recombination rate is reduced, the passivation effect of the isolation region in the back contact solar cell is improved, and the power generation efficiency of the back contact solar cell can be improved. That is to say, on one side of the first direction close to the second conductive region, the edge of the insulating structure is farther from the second conductive region than the edge of the first transmission layer, that is, the insulating structure is retracted relative to the first transmission layer. In this way, the side wall of the insulating structure, the top surface of the first transmission layer, and the side wall of the first transmission layer form a retracted step; the structure of the step makes this area no longer "steep"; compared with the insulating structure protruding from the first transmission layer or the side wall of the insulating structure being flush with the side wall of the first transmission layer, when the second transmission layer covers this area, it is relatively gentle, which is more conducive to the film formation of the second transmission layer, so that this area can be better passivated and the power generation efficiency can be improved.

[0077] The transparent conductive layer 3 is located on the side of the first transmission layer and the second transmission layer away from the silicon substrate 1, and the transparent conductive layer 3 is disconnected in the opening sub-region for electrical isolation.

[0078] Optionally, referring toFigures 1 to 12 , the first transport layer includes a tunneling oxide layer 4 and a doped polysilicon layer 5 arranged in a stack, and the tunneling oxide layer 4 is closer to the silicon substrate 1 than the doped polysilicon layer 5. The second transport layer includes an intrinsic amorphous silicon layer 6 and a doped amorphous silicon layer 7 arranged in a stack, and the intrinsic amorphous silicon layer 6 is closer to the silicon substrate 1. The doping types of the doped polysilicon layer 5 and the doped amorphous silicon layer 7 are different, and one of the doped polysilicon layer 5 and the doped amorphous silicon layer 7 is N-type doped and the other is P-type doped. Specifically, in the aforementioned opening sub-region, the transparent conductive layer 3 needs to be opened to prevent leakage at the position where the first transport layer and the second transport layer overlap. Usually, methods such as wet etching, photolithography, and laser can be used to interrupt the transparent conductive layer 3. Among them, the wet etching and photolithography methods will cause corrosion risks to the first transport layer and the second transport layer of the back contact battery, and the process steps are complex, the cost is high, and more pollutants are generated. Therefore, the laser opening method is mostly used. However, referring to Figure 13 , during the laser opening interruption process, the laser will affect the region where the first transport layer and the second transport layer overlap. Specifically, the thermal effect of the laser will cause the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 at both sides of the opening sub-region to be modified, which is the position marked by the upward red arrow. The intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 at this position will both be converted into conductive substances, forming a serious leakage channel with the doped polysilicon layer 5 below it. That is, the upward red arrow and the red arrows pointing left and right respectively indicate the schematic of the leakage channel, resulting in the carriers in the first transport layer flowing directly to the transparent conductive layer 3 in the second conductive region through this leakage channel, causing serious leakage and seriously affecting the efficiency of the back contact solar cell. The thermal effect of the laser here causing the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 at both sides of the opening sub-region to be modified can be at least one of the following three situations. One is that the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 at both sides of the opening sub-region will be modified into polysilicon doped with a doping type different from that of the doped amorphous silicon layer 7 under the action of the laser thermal effect. The doped polysilicon has the ability of lateral conduction and will form a leakage channel and short circuit with the remaining part of the doped amorphous silicon layer 7 and the doped polysilicon layer 5 below it. Another is that the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 at both sides of the opening sub-region will be modified into microcrystalline silicon or polysilicon under the action of the laser thermal effect. The conductivity of microcrystalline silicon or polysilicon is much greater than that of amorphous silicon and will form a leakage channel and short circuit with the doped polysilicon layer 5 below it. There is also one situation that the doping elements in the doped amorphous silicon layer 7 at both sides of the opening sub-region will diffuse into the intrinsic amorphous silicon layer 6, causing the intrinsic amorphous silicon layer 6 to lose its insulating effect and form a leakage channel and short circuit with the doped polysilicon layer 5 below it. Referring to Figure 14, in the present application, through the provision of the insulating structure 2 which is at least adjacent to the opening sub-region, during the process of the laser interrupting the transparent conductive layer 3 in the opening sub-region, on the one hand, due to the blocking of the insulating structure 2, the thermal influence of the laser mainly acts on the insulating structure 2 and will not directly act on the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7, thus avoiding the modification of the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 at the source, and significantly avoiding the formation of the above-mentioned leakage channels. On the other hand, even if the thermal influence of the laser causes partial modification of the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7, due to the existence of the insulating structure 2, the modified intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 and the doped polycrystalline layer 5 thereunder are electrically isolated sufficiently in the thickness direction of the silicon substrate 1, blocking the conductive path, that is Figure 14 as shown by the × within the circle in the above figure, under the above-mentioned multi-faceted effects, leakage can be prevented, and serious leakage caused by the carriers in the first transport layer flowing directly to the transparent conductive layer 3 in the second conductive region through the leakage channel can be avoided, thereby improving the efficiency of the back-contact solar cell.

[0079] For example, the doped polycrystalline layer 5 is N-type doped polysilicon, and the doped amorphous silicon layer 7 is P-type doped amorphous silicon. During the process of the laser breaking the transparent conductive layer 3 in the opening sub-region, the thermal effect of the laser will cause the intrinsic amorphous silicon layer and the P-type doped amorphous silicon on both sides of the opening sub-region to be modified into N-type doped polysilicon, which will fuse with the remaining intrinsic amorphous silicon and P-type doped amorphous silicon, forming a leakage channel with the intrinsic amorphous silicon, P-type doped amorphous silicon and the underlying N-type doped polysilicon below. Or, the thermal effect of the laser will cause the intrinsic amorphous silicon layer and the P-type doped amorphous silicon on both sides of the opening sub-region to possibly be denatured into P-type doped microcrystalline or polycrystalline silicon. The conductivity of P-type doped microcrystalline or polycrystalline silicon is much greater than that of P-type doped amorphous silicon. In particular, the conductivity of P-type doped microcrystalline or polycrystalline silicon also has a certain lateral conduction ability, forming a leakage channel with the underlying N-type doped polysilicon below. Or, the thermal effect of the laser will cause the doping elements such as boron in the P-type doped amorphous silicon on both sides of the opening sub-region to diffuse into the underlying intrinsic amorphous silicon layer, causing the underlying intrinsic amorphous silicon layer to lose its insulating effect and forming a leakage channel with the underlying N-type doped polysilicon below. The above three leakage channels will all cause the carriers in the N-type doped polysilicon to directly flow into the transparent conductive layer 3 in the P-type conductive region through the leakage channel, resulting in serious leakage. In this application, by setting the insulating structure 2, during the process of the laser breaking the transparent conductive layer 3 in the opening sub-region, on the one hand, through the blocking of the insulating structure 2, the thermal effect of the laser mainly acts on the insulating structure 2 and will not directly act on the intrinsic amorphous silicon and P-type doped amorphous silicon, which can avoid the modification of the intrinsic amorphous silicon and P-type doped amorphous silicon from the root cause and can greatly avoid the formation of the above leakage channels. On the other hand, even if the thermal effect of the laser causes partial modification of the intrinsic amorphous silicon and P-type doped amorphous silicon, due to the existence of the insulating structure 2, the modified intrinsic amorphous silicon, P-type doped amorphous silicon and the underlying N-type doped polycrystalline are fully electrically isolated in the thickness direction of the silicon substrate 1, blocking the conductive path. Under the action of the above two aspects, leakage can be prevented, and thus the efficiency of the back-contact solar cell can be improved. Moreover, on one side of the insulating structure close to the second conductive region in the first direction, the edge of the insulating structure is farther away from the second conductive region than the edge of the first transmission layer. The side of the first direction close to the second conductive region is the junction between the second conductive region and the isolation region. On the side of the first direction close to the second conductive region, the edge of the insulating structure does not protrude from the junction between the isolation region and the second conductive region. During the formation of the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7, the insulating structure will not affect the film formation of the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7, especially the passivation film layer, at the junction. The coverage of the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 is relatively comprehensive, and the film formation quality is good. The passivation effect at the junction between the isolation region and the second conductive region is good, improving the passivation effect of the isolation region (junction) in the back-contact solar cell and can improve the power generation efficiency of the back-contact solar cell.That is to say, on the side close to the second conductive region in the first direction, the edge of the insulating structure is farther away from the second conductive region than the edge of the doped polycrystalline layer 5, that is, the insulating structure is retracted relative to the doped polycrystalline layer 5, so that the side wall of the insulating structure, the top surface of the doped polycrystalline layer 5, and the side wall of the doped polycrystalline layer 5 constitute an inward step; the structure of the step makes this area no longer "steep"; compared with the insulating structure protruding from the doped polycrystalline layer 5, or the side wall of the insulating structure is flush with the side wall of the doped polycrystalline layer 5, when the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 cover this area, it is relatively flat, which is more conducive to the film formation of the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7, so that the area is better passivated and the power generation efficiency is improved.

[0080] At the same time, intrinsic amorphous silicon and doped amorphous silicon are formed on the doped polycrystalline silicon layer, and intrinsic amorphous silicon and doped amorphous silicon with good film quality can be obtained, which can further improve the passivation effect, especially the passivation effect at the junction of the isolation region and the second conductive region, and further improve the efficiency of the back contact solar cell. The doped polycrystalline layer 5 here can also be P-type doped polycrystalline silicon, and the doped amorphous silicon layer 7 here can also be N-type doped amorphous silicon, and the specific doping type is not limited.

[0081] It should be noted that the harm of the leakage channel here mainly lies in the stacked sub-region adjacent to the second conductive region, because even if the leakage channel is formed in the position adjacent to the first conductive region, the current will still be conducted out through the transparent conductive layer on the first conductive region. For example, Figure 13 and Figure 14 In the embodiment, the carriers in the N-type doped polysilicon will still flow into the transparent conductive layer 3 in the N-type conductive area, so there is basically no effect on the conduction of the carriers in the first conductive area to the transparent conductive layer. Therefore, in the present application, the insulating structure 2 must at least be located in the first stacked sub-area.

[0082] Alternatively, optionally, the first transmission layer and the second transmission layer both include: a stacked tunneling oxide layer 4 and a doped polysilicon layer 5, in which the tunneling oxide layer 4 is closer to the silicon substrate 1 than the doped polycrystalline layer 5, and the doping types of the doped polycrystalline layer 5 in the first transmission layer and the second transmission layer are different. The first transmission layer and the second transmission layer of the back-contact solar cell are flexible and diverse. The first transmission layer and the second transmission layer here are the same or similar to the technical problems and beneficial effects solved by the aforementioned first transmission layer and the second transmission layer, and will not be described again here to avoid repetition.

[0083] Alternatively, optionally, both the first transport layer and the second transport layer include: an intrinsic amorphous silicon layer 6 and a doped amorphous silicon layer 7 which are stacked, and in both the first transport layer and the second transport layer, the intrinsic amorphous silicon layer 6 is closer to the silicon substrate 1 than the doped amorphous silicon layer 7. The doping types of the doped amorphous layers in the first transport layer and the second transport layer are different. The first transport layer and the second transport layer of this back-contact solar cell are flexible and diverse. The first transport layer and the second transport layer here solve the same or similar technical problems and have the same or similar beneficial effects as the aforementioned first transport layer and second transport layer. To avoid repetition, they will not be elaborated here.

[0084] It should be noted that this back-contact solar cell may further include a first electrode 8 and a second electrode 9. The first electrode 8 is located on the transparent conductive layer 3 of the first conductive region, and the second electrode 9 is located on the transparent conductive layer 3 of the second conductive region. The first electrode 8 and the second electrode 9 are used to conduct current outward. No specific limitations are imposed on the size, material, etc. of the first electrode 8 and the second electrode 9.

[0085] It should be noted that when the first transport layer is an N-type transport layer, then the second transport layer is a P-type transport layer. The first conductive region on the first surface may be a polished structure, and the second conductive region may be a textured structure. Specifically, the thickness of the tunneling oxide layer 4 in the first transport layer is very thin, and it is easy to grow this tunneling oxide layer on a flat polished structure. The doped polysilicon layer 5 in the first transport layer is N-type doped polysilicon, and the doped amorphous silicon layer 7 in the second transport layer is P-type doped amorphous silicon. By setting the second conductive region as a textured structure, the adhesion of the P-type doped amorphous silicon can be improved, and the conductivity of the P-type doped amorphous silicon can also be improved, further improving the efficiency of the back-contact solar cell.

[0086] Optionally, referring to Figures 1 to 3 , on this first surface, the projection of the insulating structure 2 and the projection of the opening sub-region do not overlap. Figures 1 to 3 In

[0087] Optionally, referring to Figure 4 、 Figure 6 、 Figure 7 and Figure 8, on this first surface, the projection of the insulating structure 2 and the projection of the opening sub-region only partially overlap, and there is also a non-overlapping part. That is to say, on this first surface, the insulating structure 2 extends into the opening sub-region. The part of the insulating structure 2 that extends into the opening sub-region can play a good protective role for the underlying structure during the process of forming the opening in the transparent conductive layer 3, and the structure of the back-contact solar cell is flexible and diverse.

[0088] Optionally, referring to Figure 5 、 Figures 9 to 12 , on this first surface, the projection of the opening sub-region is located within the projection of the insulating structure 2. That is to say, along the first direction M on this first surface, the insulating structure 2 extends into the opening sub-region, and the insulating structure 2 completely covers the opening sub-region. The part of the insulating structure 2 that overlaps with the projection of the opening sub-region can play a good protective role for the underlying structure during the process of forming the opening in the transparent conductive layer 3, and the structure of the back-contact solar cell is flexible and diverse.

[0089] Optionally, the material of the insulating structure 2 can be selected from at least one of silicon oxide, silicon nitride, and silicon oxynitride. The above materials have good insulation performance.

[0090] Optionally, the insulating structure 2 contains doping elements. The doping elements can be provided separately by a doping source into the insulating structure, or can be doped elements in the transport layer or the silicon substrate that diffuse into the insulating structure. It should be noted that although the insulating structure 2 contains doping elements, the insulating structure 2 still has good insulation effect. The insulating structure 2 can contain P-type doping elements and N-type doping elements, that is, the insulating structure 2 can contain both P-type and N-type doping elements at the same time. In this case, the insulating structure 2 still has good insulation effect. Here, mainly through the principle of doping compensation, the conductive effect of this region is reduced or offset to form an insulating structure.

[0091] Optionally, referring to Figure 2 、 Figure 3 、 Figure 8 、 Figures 10 to 12 , when the insulating structure 2 is in the first transport layer within the first stacked sub-region, the thickness of the insulating structure 2 is 0.1 nm - 20 nm. The thickness of the insulating structure 2 within this range not only has good insulation effect, but also is easy to prepare, that is, a good balance is achieved between the insulation effect and the forming process.

[0092] For example, when the insulating structure 2 is in the first transmission layer within the first stacked sub-region, the thickness of the insulating structure 2 can be 0.1 nm, 0.5 nm, 1 nm, 1.5 nm, 5 nm, 8 nm, 10 nm, 11 nm, 12.5 nm, 15 nm, 14.6 nm, 18 nm, 20 nm.

[0093] Optionally, referring to Figure 14 The back-contact solar cell further includes: a thermal influence structure 10, which is located on the side of the insulating structure 2 away from the silicon substrate 1, and the thermal influence structure 10 is in contact with the insulating structure 2. In the thickness direction of the silicon substrate 1, the projection of the thermal influence structure 10 falls within the projection of the insulating structure 2. The second transmission layer includes a thermal influence structure and a non-thermal influence structure; the conductivity of the thermal influence structure is less than that of the non-thermal influence structure. For example, Figure 14 the second transmission layer in can include: an intrinsic amorphous silicon layer 6, a doped amorphous silicon layer 7, and the thermal influence structure 10 at. The thermal influence structure 10 can be a structure obtained by modifying a portion of the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 near the opening sub-region. The unmodified portions of the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 are the non-thermal influence structures here. The conductivity of the thermal influence structure 10 is smaller than that of the non-thermal influence structure, which can avoid leakage. Specifically, the thermal influence structure 10 here has certain conductivity. When using a laser to open the transparent conductive layer 3 in the opening sub-region, the thermal influence structure 10 can include, under the blocking effect of the insulating structure 2, the modified portion of the second transmission layer in the first stacked sub-region adjacent to the opening sub-region by the thermal influence of the laser. Since the thermal influence structure 10 has certain conductivity, through the setting of the insulating structure 2, and in the thickness direction of the silicon substrate 1, the projection of the thermal influence structure 10 falls within the projection of the insulating structure 2, thereby electrically isolating the modified intrinsic amorphous silicon, doped amorphous silicon, and the underlying doped polycrystal sufficiently in the thickness direction of the silicon substrate 1, blocking the conductive path, and fully preventing leakage, thereby improving the efficiency of the back-contact solar cell. Here, in the thickness direction of the silicon substrate 1, the projection of the thermal influence structure 10 can specifically be equal in size and exactly coincide with the projection of the insulating structure 2, or, referring to Figure 14 , the projection of the thermal influence structure 10 is smaller than the projection of the insulating structure 2, and the projection of the thermal influence structure 10 is located within the projection of the insulating structure 2. The specific form is not limited, and the limitation is to fully prevent leakage.

[0094] It should be noted that the thickness direction of the silicon substrate 1 mentioned in this application is parallel to the thickness direction of the back-contact solar cell. For example, Figures 1 to 14 , the thickness direction of the silicon substrate 1 and the thickness direction of the back-contact solar cell are both the up-down direction.

[0095] Optionally, referring to Figure 1 , in the first direction M, the width d1 of the insulating structure 2 is 10 nm to 100 μm. By precisely limiting the width d1 of the insulating structure 2, the passivation effect and the insulating effect at the junction of the isolation region and the second conductive region of the back-contact solar cell are both excellent, and the insulating structure 2 of this size is also easy to mass-produce. In the first direction M, the width d1 of the insulating structure 2 can be further set to 10 nm to 25 μm, or the d1 can be further set to 10 nm to 100 nm. For example, in the first direction M, the width d1 of the insulating structure 2 can be 10 nm, 20 nm, 50 nm, 55 nm, 70 nm, 80 nm, 100 nm, 500 nm, 1 μm, 1.3 μm, 1.8 μm, 20 μm, 2.5 μm, 10 μm, 12.5 μm, 25 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm.

[0096] Optionally, in the first direction M, the width of the thermal influence structure 10 is 0.1 μm to 20 μm. In the case where the insulating structure 2 is provided, due to the blocking of heat by the insulating structure 2 during the process of interrupting the transparent conductive layer, the size of the thermal influence region 10 is smaller and the leakage risk is smaller. Moreover, the processing process window corresponding to the size of the thermal influence structure 10 is wider. It should be noted that it is necessary to ensure that in the first direction, the width d1 of the insulating structure 2 is greater than or equal to the width of the thermal influence structure 10. In the first direction, the direction in which the width d1 of the insulating structure 2 is located is parallel to the direction in which the width of the thermal influence structure 10 is located.

[0097] For example, in the first direction M, the width of the thermal influence structure 10 can be 100 nm, 200 nm, 500 nm, 800 nm, 1 μm, 3 μm, 8 μm, 10 μm, 12.5 μm, 15 μm, 17 μm, 20 μm.

[0098] Optionally, referring to Figures 1 to 12, on one side close to the second conductive region in the first direction M, the distance d2 between the edge of the insulating structure 2 and the edge of the first transmission layer is 5 nm to 50 μm. On one side close to the second conductive region in the first direction M, the distance d2 between the edge of the insulating structure 2 and the edge of the first transmission layer is within this range. During the formation of the second transmission layer, the insulating structure 2 basically does not affect the formation of the second transmission layer, and the film-forming quality of the passivation film layer of the second transmission layer at this junction is good, improving the passivation effect of the back-contact solar cell. Moreover, when the distance d2 between the edge of the insulating structure 2 and the edge of the first transmission layer is within this range, the insulating structure 2 also has a good blocking effect on the aforementioned leakage channel. Here, the d2 can be further set to 5 nm to 25 μm, or can be further set to 10 nm to 100 nm, further taking into account the processing windows of each film layer.

[0099] For example, on one side close to the second conductive region in the first direction M, the distance d2 between the edge of the insulating structure 2 and the edge of the first transmission layer can be 5 nm, 10 nm, 15 nm, 50 nm, 55 nm, 70 nm, 30 nm, 100 nm, 1 μm, 5 μm, 15 μm, 20 μm, 25 μm, 12.5 μm, 30 μm, 40 μm, 45 μm, 50 μm.

[0100] Optionally, referring to Figure 1 , Figure 2 , Figure 4 , the isolation region is composed of a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region. The second transmission layer is at least located on the second conductive region and the first stacked sub-region. One formation method of this battery structure can be that during the process of opening the transparent conductive layer 3 in the opening sub-region, the second transmission layer located on the first transmission layer adjacent to the opening position can also be removed together. Therefore, there is no second stacked sub-region adjacent to both the opening sub-region and the first conductive region in this battery. Then, compared with the case where the second stacked sub-region still exists, Figure 1 , Figure 2 , Figure 4 in the back-contact solar cell shown, the transmission path between the first transmission layer and the transparent conductive layer 3 thereon is reduced, the transmission resistance can be reduced, the current loss can be reduced, and the power generation efficiency of the back-contact solar cell can be further improved.

[0101] Or, optionally, referring to Figure 3 , Figures 5 to 12, the isolation region is composed of a first stacked sub-region adjacent to the second conductive region, an opening sub-region adjacent to the first stacked sub-region, and a second stacked sub-region adjacent to the first conductive region. Here, the second stacked sub-region is the part between the dashed line L2 and the dashed line L7 on the first surface. The second transmission layer is at least located on the second conductive region, the first stacked sub-region, and the second stacked sub-region. The form of the isolation region of the back-contact solar cell is flexible and diverse, and can be applied to various application scenarios.

[0102] Optionally, the back-contact solar cell further includes: a weather-resistant oxide layer filled on the underlying structure below the disconnection position of the transparent conductive layer 3. The mass proportion of oxygen atoms in the weather-resistant oxide layer is greater than or equal to 70%. Specifically, after the transparent conductive layer 3 is disconnected in the opening sub-region, the underlying structure at the disconnection position will be partially exposed. The exposed part on the underlying structure is usually invaded by water vapor, etc., which will reduce the weather resistance of the back-contact solar cell and affect the performance parameters of the back-contact solar cell. In this application, after the transparent conductive layer is disconnected in the opening sub-region, the underlying structure at the disconnection position is partially exposed, and a weather-resistant oxide layer is provided on the exposed part of the underlying structure. The higher the oxygen atom concentration in the weather-resistant oxide layer, the greater the refractive index and the denser the weather-resistant oxide layer. In this application, the oxygen atom concentration in the weather-resistant oxide layer is relatively high, which can avoid the invasion of water vapor, etc., improve the weather resistance of the back-contact solar cell, and enable the back-contact solar cell to maintain good performance parameters. Moreover, the weather-resistant oxide layer has good insulation properties. The weather-resistant oxide layer located in the isolation region can further increase the isolation effect. At the same time, the weather-resistant oxide layer can also play a role in blocking metal ions during the formation of the metal electrode, preventing metal ions from diffusing into the interior of the back-contact solar cell.

[0103] The mass proportion of oxygen atoms in the weather-resistant oxide layer can specifically refer to: in a part at any position in the weather-resistant oxide layer, the mass proportion of oxygen atoms in this part. The mass proportion of oxygen atoms in the weather-resistant oxide layer can be obtained by means such as XPS (X-ray Photoelectron Spectroscopy). There is no specific limitation on the method for obtaining the mass proportion of oxygen atoms in the weather-resistant oxide layer.

[0104] For example, the mass proportion of oxygen atoms in the weather-resistant oxide layer can be: 70%, 73%, 75%, 78%, 80%, 81%, 85%, 88%, 89%, 90%, 93%.

[0105] It should be noted that after the transparent conductive layer is disconnected in the opening sub-region, the structure below the disconnection position can be the second transmission layer, or can be the insulating structure 2, or can be the first transmission layer, and no specific limitation is made. After the transparent conductive layer is disconnected in the opening sub-region, the structure that will be exposed at the disconnection position can be the underlying structure, and the weather-resistant oxide layer is provided on the underlying structure. The formation method of the weather-resistant oxide layer can be: during the process of disconnecting the transparent conductive layer by laser, directly forming the weather-resistant oxide layer on the underlying structure by using the laser, or after the underlying structure is exposed, forming the weather-resistant oxide layer by wet ozone, dry ozone, or sintering method. No specific limitation is made on the specific formation method, specific shape and size, etc. of the weather-resistant oxide layer.

[0106] Optionally, referring to Figure 7 , Figure 8 In the part outlined by the red box in, the edge of the first transmission layer in the first stack sub-region contacts the edge of the second transmission layer in the first stack sub-region, and together with the transparent conductive layer 3 thereon, forms a hot-spot prevention structure. Specifically, usually, the resistance at a certain position in the back-contact solar cell is relatively large, which may cause heat accumulation. In this application, the edge of the doped polysilicon layer 5 in the first transmission layer in the first stack sub-region contacts the edge of the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 in the second transmission layer in the first stack sub-region. The doped polysilicon layer 5 in the first transmission layer and the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 in the second transmission layer that make contact above will conduct when the voltage is greater than or equal to their breakdown voltage. At the contact position, the current is longitudinally transmitted from the underlying doped polysilicon layer 5, intrinsic amorphous silicon layer 6, and the upper doped amorphous silicon layer 7 to the upper transparent conductive layer 3, and the current is conducted out. Or, the current is laterally conducted from the doped polysilicon layer 5, intrinsic amorphous silicon layer 6, and doped amorphous silicon layer 7 to the transparent conductive layer 3 near the second conductive region, and the current is conducted out. Thus, it is possible to prevent the heat generated by a relatively large resistance from accumulating at the above contact position, and it can play a role in preventing hot spots, that is, there is a reverse leakage part between the second conductive region and the first sub-stack region that can play a role in preventing hot spots.

[0107] Referring to Figure 1 , Figures 4 to 7 , Figure 9, the insulating structure 2 is at least located between the first transmission layer and the second transmission layer within the first stacked sub-region. The thickness of the insulating structure 2 is less than or equal to 150 nm. The insulating structure 2 located between the first transmission layer and the second transmission layer within the first stacked sub-region is separately provided. With the thickness of the insulating structure 2 within the above range, not only is the insulation effect good, but it is also easy to fabricate. The direction in which the thickness of the insulating structure 2 lies is parallel to the direction in which the thickness of the silicon substrate 1 lies. For example, the insulating structure 2 is at least located between the first transmission layer and the second transmission layer within the first stacked sub-region, and the thickness of the insulating structure 2 can be 150 nm, 120 nm, 130 nm, 100 nm, 90 nm, 80 nm, 70 nm, 60 nm, 50 nm, 30 nm, 20 nm, 10 nm.

[0108] Optionally, the insulating structure has at least one of crystalline silicon, crystalline silicon nitride, and crystalline silicon oxynitride. The insulating structures of the above materials have good insulation effects, are easy to fabricate, and are relatively compatible with the existing fabrication processes of back-contact solar cells. Here, crystalline silicon refers to silicon with a crystallization rate greater than 0, crystalline silicon nitride refers to silicon nitride with a crystallization rate greater than 0, and crystalline silicon oxynitride refers to silicon oxynitride with a crystallization rate greater than 0.

[0109] Optionally, referring to Figure 4 , Figure 5 , Figure 7 , Figure 8 , Figure 9 , Figure 11 , Figure 12 and Figure 14 , the insulating structure 2 further includes: a protruding portion on the first surface that projects outside the projection of the opening sub-region along the first direction M; on the first surface, the region between the dashed line L5 and the dashed line L7 is the opening sub-region, and the insulating structure 2 further includes: a protruding portion located on the right side of the dashed line L5 and / or on the left side of the dashed line L7. In the insulating structure, the portion that overlaps the projection of the opening sub-region on the first surface is the overlapping portion, that is, the portion of the insulating structure located between the dashed line L5 and the dashed line L7 is the overlapping portion, and the structures of the protruding portion and the overlapping portion are different. Here, the different structures can refer to: crystallization rate, flatness, insulation resistance, thickness, etc. The requirement for electrical isolation of the overlapping portion may be greater than that of the protruding portion, and the requirement for the film formation quality of the remaining film layers on the protruding portion may be greater than that of the remaining film layers on the overlapping portion. Since the functions required by the protruding portion and the overlapping portion are slightly different, the structures of the protruding portion and the overlapping portion are different. The structures of the protruding portion and the overlapping portion can be respectively adapted to the required functions, so that not only is the insulation effect good, but also the passivation effect at the junction position, especially at the junction of the isolation region and the second conductive region, is better, improving the passivation effect of the isolation region (junction) in the back-contact solar cell, and can improve the power generation efficiency of the back-contact solar cell.

[0110] Optionally, the material properties of the protruding portion and the overlapping portion are different. The properties here can be: crystallization rate, flatness, insulation resistance, etc.; and / or, the thicknesses of the protruding portion and the overlapping portion are different. The material properties of the protruding portion and the overlapping portion are different, and the structures of the protruding portion and the overlapping portion can be respectively adapted to the required functions. Thus, not only is the insulation effect good, but also the passivation effect at the junction position, especially at the junction of the isolation region and the second conductive region, is better, improving the passivation effect of the isolation region (junction) in the back contact solar cell, and the power generation efficiency of the back contact solar cell can be improved. Here, the thickness of the protruding portion may be greater than the thickness of the overlapping portion.

[0111] Optionally, the insulating structure between the first transmission layer and the second transmission layer in the first stacked sub-region includes: a silicon nitride layer and a silicate glass layer stacked. The silicate glass layer is close to the silicon substrate. The insulating structure of the above stacked structure has a good insulating effect, and moreover, the silicate glass layer will be formed incidentally at the position of the first transmission layer close to the silicon substrate during the formation of the first transmission layer, and the process compatibility is good.

[0112] Optionally, along the thickness direction of the silicon substrate, the insulating structure includes: a third region and a fourth region. The third region is closer to the silicon substrate than the fourth region, that is, the third region is closer to the silicon substrate and the fourth region is farther from the silicon substrate. The crystallization degree of the fourth region is greater than that of the third region, or in other words, the crystallization rate at the position farther from the silicon substrate in the insulating structure is higher. The higher the crystallization rate, the denser it is, and from the side far from the silicon substrate, the barrier effect on water vapor, etc. is stronger, and the weather resistance is better. Moreover, the insulating structure with a higher crystallization rate can also play a role in blocking metal ions during the formation of the metal electrode, preventing metal ions from diffusing into the back contact solar cell. Here, the relative thickness sizes of the third region and the fourth region are not limited, and the difference in crystallization degree is not specifically limited.

[0113] Optionally, along the thickness direction of the silicon substrate, the insulating structure includes: a third region and a fourth region. The third region is closer to the silicon substrate than the fourth region, that is, the third region is nearer to the silicon substrate and the fourth region is farther from the silicon substrate. The ratio of the number of silicon atoms to the number of nitrogen atoms in the fourth region is greater than that in the third region. The ratio of the number of silicon atoms to the number of nitrogen atoms at a position farther from the silicon substrate in the insulating structure is larger, that is, there are more silicon atoms, fewer nitrogen atoms, and more oxygen atoms at a position farther from the silicon substrate in the insulating structure. The position farther from the silicon substrate in the insulating structure is denser, which can prevent the invasion of water vapor and the like, improve the weather resistance of the back-contact solar cell, and enable the back-contact solar cell to maintain good performance parameters. Moreover, the denser the position farther from the silicon substrate in the insulating structure is, the further the isolation effect can be increased, and it can also play a role in blocking metal ions during the formation of the metal electrode, preventing metal ions from diffusing into the interior of the back-contact solar cell. The relative thicknesses of the third region and the fourth region are not limited here, and the magnitude of the difference in the ratio of the number of silicon atoms to the number of nitrogen atoms is not specifically limited.

[0114] The present application also provides a method for manufacturing a back-contact solar cell, and this manufacturing method can be used to manufacture any of the aforementioned back-contact solar cells. This method may include the following steps.

[0115] Step 101: Provide a silicon substrate; the silicon substrate includes: opposite first and second surfaces; the first surface includes: a first conductive region, a second conductive region, and an isolation region located between the first conductive region and the second conductive region; the direction in which the first conductive region, the isolation region, and the second conductive region are sequentially distributed is the first direction; the isolation region includes: a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region.

[0116] This step 101 can refer to the foregoing description. To avoid repetition, it will not be elaborated here.

[0117] Step 102: Form a first transmission layer on the first conductive region and the isolation region.

[0118] The first transmission layer can be formed by means such as low-pressure chemical vapor deposition (LPCVD) on the first conductive region and the isolation region. The specific formation method of the first transmission layer is not limited.

[0119] Step 103: modifying the first transmission layer at least located in the first stacking sub-region, converting the first transmission layer at least located in the first stacking sub-region into an insulating structure; and / or forming an insulating structure on the first transmission layer at least located in the first stacking sub-region; in the first direction, the insulating structure is farther away from the second conductive region than the first transmission layer.

[0120] The modification here can be a laser modification or the like, converting the first transmission layer at least located in the first stack sub-region into an insulating structure, and / or forming an insulating structure separately and specifically on the first transmission layer at least located in the first stack sub-region. For example, laser modification will modify doped polysilicon into silicon oxide, etc. In the laser modification method, since the formed insulating structure 2 is closer to the second conductive region in the first direction, the edge of the insulating structure is farther away from the second conductive region than the edge of the first transmission layer, and the area directly hit by the laser has certain damage, and the second transmission layer is directly formed on the laser modified region, and its film quality may be poor. Therefore, in the present application, the second transmission layer at the junction is not initially set on the laser-modified insulating structure 2, but is first set on the un-laser-modified first transmission layer, and then on the laser-modified insulating structure 2. Through a transition stage, the direct film formation defects at the junction are avoided, so that the film formation quality and passivation effect are greatly improved, and the defects are made as close as possible to the inside of the first stack sub-region to improve the film formation quality and passivation effect of the two transmission layers at the junction. The insulating structure formed separately and specifically can be made of silicon nitride or the like, and is not specifically limited thereto.

[0121] Step 104, forming a second transmission layer at least on the second conductive region and the first stacked sub-region; the second transmission layer is located on a side of the insulating structure away from the silicon substrate; the first transmission layer and the second transmission layer have different conductivity types.

[0122] The second transmission layer may be formed by plasma assisted chemical vapor deposition (PECVD) or the like, and the specific formation method of the second transmission layer is not limited.

[0123] Step 105 : forming a transparent conductive layer located on a side of the first transmission layer and the second transmission layer away from the silicon substrate and disconnected in the opening sub-region.

[0124] The transparent conductive layer 3 may be formed by magnetron sputtering or the like, and the specific method for forming the transparent conductive layer 3 is not limited.

[0125] The transparent conductive layer 3 can be cut by wet etching, photolithography, laser, etching paste, etc., and the method of cutting the transparent conductive layer 3 is not specifically limited. Cutting the transparent conductive layer 3 by etching paste will not cut the structure below the transparent conductive layer 3.Figure 6 , Figure 10 , the etch paste is used to interrupt the transparent conductive layer 3, and the intrinsic amorphous silicon layer 6 and the doped amorphous silicon layer 7 at the disconnection position are not disconnected.

[0126] Optionally, forming the first transmission layer in the foregoing step 102 includes: sequentially fabricating the entire layer of the first transmission layer and the mask layer on the first surface of the silicon substrate, and LPCVD or the like can be used here; laser irradiating the portion of the mask layer located on the second conductive region, so that the portion of the mask layer located on the second conductive region is modified, and wet processing is performed. During the wet processing, the mask layer and the first transmission layer located on the second conductive region are removed, and the laser-damaged portion is also removed during the wet processing, so that the second conductive region on the first surface of the silicon substrate is exposed, and the mask layer and the first transmission layer located on the first conductive region and the isolation region are retained. The foregoing step 103 may include: laser irradiating at least the portion of the mask layer located in the first stacked sub-region, so that at least the mask layer within the first stacked sub-region is modified to obtain at least a partial insulating structure. This method directly forms at least a partial insulating structure by means of the mask layer during the patterning process of the first transmission layer, has high compatibility with the patterning process of the first transmission layer, and the process of forming the insulating structure is simple. The mask layer may be a silicon nitride layer or the like, and the remaining unmodified mask layer will be removed subsequently, so that the first transmission layer thereunder is exposed for subsequent process steps.

[0127] The present application also provides another method for manufacturing a back-contact solar cell, and this manufacturing method can be used to manufacture any of the foregoing back-contact solar cells. This method may include the following steps.

[0128] Step 201, providing a silicon substrate; the silicon substrate includes: opposite first and second surfaces; the first surface includes: a first conductive region, a second conductive region, and an isolation region located between the first conductive region and the second conductive region; the direction in which the first conductive region, the isolation region, and the second conductive region are sequentially distributed is the first direction; the isolation region includes: a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region.

[0129] Step 202, forming a first transmission layer on the first conductive region and the isolation region.

[0130] The first transmission layer on the first conductive region and the isolation region can be formed by means of low-pressure chemical vapor deposition (LPCVD) or the like, and the specific formation method of the first transmission layer is not limited.

[0131] Step 203: Prepare a second transmission layer on the second conductive region and the first transmission layer; the first transmission layer and the second transmission layer have different conductivity types.

[0132] The second transmission layer may be formed by plasma assisted chemical vapor deposition (PECVD) or the like, and the specific formation method of the second transmission layer is not limited.

[0133] Step 204, using laser to irradiate the position of the second transmission layer located in the isolation region, so that the first transmission layer and the second transmission layer located at the local position in the isolation region are co-doped to form an insulating structure; the laser irradiation width is less than or equal to the width of the isolation region; the direction of the width is parallel to the first direction.

[0134] Here, the laser is used to irradiate the position in the second transmission layer within the isolation region, and the main doping element in the second transmission layer at the position is pushed into the first transmission layer at the position, so that the first transmission layer and the second transmission layer at the position are co-doped to form an insulating structure. The laser irradiation width here is less than or equal to the width of the isolation region, which can ensure that the co-doped region basically does not exceed the isolation region, and the direction of the width here is parallel to the aforementioned first direction.

[0135] Specifically, the area can be processed using, for example, a green light laser, with a processing width less than or equal to the width of the isolation area. The main doping elements in the second transmission layer are pushed into the first transmission layer to form a co-doping structure. The conductive effect of the area is reduced or offset through the principle of doping compensation to form an insulating structure.

[0136] Step 205 : forming a transparent conductive layer located on a side of the first transmission layer and the second transmission layer away from the silicon substrate and disconnected in the opening sub-region.

[0137] The transparent conductive layer 3 may be formed by magnetron sputtering or the like, and the specific forming method of the transparent conductive layer 3 is not limited. The transparent conductive layer 3 may be interrupted by wet etching, photolithography, laser, etching paste or the like, and the method of disconnecting the transparent conductive layer 3 is not specifically limited. Here, the relevant records of the aforementioned step 105 may be referred to, and will not be described here in detail to avoid repetition.

[0138] The present application may also provide a photovoltaic module, which may include any one of the aforementioned back-contact solar cells. The photovoltaic module may also include: an encapsulation film located on the light-facing side and the backlight side of the back-contact solar cell, etc., and the specific structure of the photovoltaic module is not limited.

[0139] It should be noted that the photovoltaic module and the method for manufacturing the back-contact solar cell have the same or similar beneficial effects as any of the foregoing back-contact solar cells. To avoid repetition, they will not be elaborated here.

[0140] The present application will be further explained below with reference to specific embodiments.

[0141] Embodiment 1

[0142] In the first step, wet polishing is performed on the silicon substrate. The wet polishing scheme mainly includes two steps: cleaning and alkaline polishing.

[0143] The cleaning steps are as follows: (1) Use SC1 (Standard Clean 1) in the RCA cleaning (industrial standard wet cleaning) process for cleaning. (2) Then, rinse with deionized water to neutralize the chemicals remaining after SC1 cleaning; the alkaline polishing steps: (1) Use KOH to remove the surface damage layer caused by cutting, and the surface of the silicon substrate is polished; (2) Subsequently, perform high-efficiency SC1 cleaning; (3) Use SC2 (Standard Clean 2 in industrial standard wet cleaning) to remove the residual metal ions; (4) Finally, clean with 5% wt (mass concentration of 5%) hydrofluoric acid to complete the polishing of the silicon substrate surface. The polishing thickness of the front and back surfaces of the silicon substrate is 5 μm - 10 μm, and a silicon substrate with different crystal orientations is formed on the polished silicon substrate surface. The silicon substrate includes: a first surface and a second surface opposite to each other, and the first surface is the backlight surface of the subsequent back-contact solar cell. The first surface includes: a first conductive region, a second conductive region, and an isolation region located between the first conductive region and the second conductive region. The direction in which the first conductive region, the isolation region, and the second conductive region are sequentially distributed is the first direction. The isolation region includes: a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region.

[0144] In the second step, the preparation of the first transmission layer and the mask layer: The first transmission layer includes a tunneling oxide layer 4 and a doped polycrystalline layer 5.

[0145] The specific implementation method is as follows: First, prepare the tunneling oxide layer 4 in an LPCVD device, and then deposit polysilicon. Then, prepare the doped polycrystalline layer 5 through a phosphorus diffusion device. A mask layer is prepared on the doped polycrystalline layer, and the mask layer is a silicon nitride mask layer.

[0146] In the third step, pattern the first transmission layer: Use laser to irradiate the part of the mask layer located on the second conductive region, so that the mask layer located on the second conductive region is modified, and perform wet treatment. Here, the wet treatment can be polishing or texturing with an alkaline solution to remove the mask layer and the first transmission layer located on the second conductive region, so that the second conductive region is exposed. Then, perform pickling to remove the remaining mask layer, and retain the first transmission layer located on the first conductive region and the isolation region.

[0147] Fourth step, laser oxidation modification: Laser oxidation is performed on the surface of the doped polycrystalline layer 5. The laser oxidation position is located in the first stacked sub-region, on the side closer to the second conductive region in the first direction. The distance between the edge of the laser oxidation modification region and the edge of the first transmission layer is 30 μm. In this first direction, the width of the laser oxidation modification region is 10 μm to 100 μm, and the oxidation depth is less than or equal to 10 nm. Furthermore, on the side closer to the second conductive region in the first direction, the distance d2 between the edge of the insulating structure 2 and the edge of the first transmission layer is 30 μm, the width of the insulating structure 2 is approximately 10 μm to 100 μm, and the depth of the insulating structure 2 is less than or equal to 10 nm. The laser oxidation modification step is before the preparation of the second transmission layer.

[0148] Fifth step, prepare the front passivation layer and antireflection layer. The passivation layer is: AlO (aluminum oxide), and the antireflection layer is: SiN x (silicon nitride), where x in this chemical formula is greater than 0.

[0149] Sixth step, prepare the second transmission layer. The second transmission layer with the opposite polarity to the first transmission layer is prepared by a low-temperature method such as PECVD. The second transmission layer includes intrinsic amorphous silicon 6 and a doped amorphous silicon layer 7. Next, laser spaced grooving is performed in a partial region of the first conductive region to process a part of the second transmission layer on the first transmission layer, and the laser-processed second transmission layer is removed by wet etching to expose a part of the first transmission layer in the first conductive region.

[0150] Seventh step, prepare a continuous transparent conductive layer 3. The transparent conductive layer 3 is prepared over the entire surface, such as: ITO.

[0151] Eighth step, insulate the first transmission layer and the second transmission layer. The transparent conductive layer is opened by laser in the opening sub-region to insulate the first transmission layer and the second transmission layer. The insulation position is above the above-mentioned laser oxidation modification region, and its width is less than the width of the laser oxidation modification region.

[0152] Ninth step, metallization. Electrodes are prepared on the first transmission layer and the second transmission layer.

[0153] The back-contact solar cell formed in Example 1 can be as Figure 8 etc. shown.

[0154] Example 2

[0155] The main difference between Example 2 and Example 1 is that the preparation method of the insulating structure 2 is different. Compared with Example 1, the third and fourth steps in Example 2 are different from those in Example 1. The third and fourth steps in Example 2 are mainly explained below.

[0156] Step 3: Pattern the first transmission layer: Use a laser to irradiate the part of the mask layer located on the second conductive region, so that the mask layer located on the second conductive region is modified, and then perform wet processing. The wet processing here can be polishing or texturing with an alkaline solution to remove the mask layer and the first transmission layer located on the second conductive region, exposing the second conductive region.

[0157] Step 4: Prepare the insulating structure 2 by using laser-modified SiN x (x > 0). Specifically, use a laser to irradiate at least the part of the mask layer located within the first stacked sub-region for local laser modification. The modified SiN x is more acid-resistant and can be retained during the subsequent pickling process. The modified mask layer at this position forms the insulating structure. Then, pickle to remove the remaining mask layer, and retain the first transmission layer located on the first conductive region and the isolation region, as well as the just-formed insulating structure.

[0158] Next, prepare the front passivation layer and the antireflection layer. The passivation layer is: AlO, and the antireflection layer is: SiN x .

[0159] The rest of Example 2 is the same as that of Example 1. To avoid repetition, it will not be elaborated here.

[0160] The back-contact solar cell formed in Example 2 can be as shown in Figure 5 , Figure 7 etc.

[0161] Example 3

[0162] The main difference between Example 3 and Example 1 lies in the different preparation methods of the insulating structure 2. Compared with Example 1, there is no Step 4 in Example 3. In Example 3, after preparing the patterned second transmission layer and before preparing the continuous transparent conductive layer, the insulating structure is formed. The following mainly explains the steps of forming the insulating structure in Example 3.

[0163] Specifically, use a green laser to irradiate the position within the isolation region of the second transmission layer, and push the main doping element in the second transmission layer at this position into the first transmission layer at this position, so that the first transmission layer and the second transmission layer at this position are co-doped to form the insulating structure. Here, the conductive effect of this region is mainly reduced or offset through the principle of doping compensation to form the insulating structure. The width of the laser irradiation here is less than or equal to the width of the isolation region, which can ensure that the co-doped region basically does not exceed the isolation region. The direction of the width is parallel to the aforementioned first direction.

[0164] The rest of Example 3 is the same as that of Example 1. To avoid repetition, it will not be elaborated here.

[0165] It should be noted that, in this article, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including such element.

[0166] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A back contact solar cell, characterized in that: include: Silicon substrate; The silicon substrate comprises: a first surface and a second surface opposite to each other; the first surface comprises: a first conductive region, a second conductive region and an isolation region between the first conductive region and the second conductive region; the first conductive region, the isolation region and the second conductive region are sequentially distributed in a first direction; the isolation region comprises: a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region; a first transmission layer, located on the first conductive region and the isolation region; a second transmission layer, located at least on the second conductive region and the first stacked sub-region, and in the first stacked sub-region, the second transmission layer is located on a side of the first transmission layer away from the silicon substrate; the first transmission layer and the second transmission layer have different conductivity types; an insulating structure, at least in the first transmission layer within the first stacking sub-region, and / or at least between the first transmission layer and the second transmission layer within the first stacking sub-region; and on a side close to the second conductive region in the first direction, an edge of the insulating structure is farther away from the second conductive region than an edge of the first transmission layer; A transparent conductive layer is located on a side of the first transmission layer and the second transmission layer away from the silicon substrate; the transparent conductive layer is disconnected in the opening sub-region.

2. The back contact solar cell according to claim 1, characterized in that: On the first surface, a projection of the insulating structure and a projection of the opening sub-region do not overlap.

3. The back contact solar cell according to claim 1, characterized in that: On the first surface, a projection of the opening sub-region is located within a projection of the insulating structure.

4. The back contact solar cell according to claim 1, characterized in that: On the first surface, a projection of the opening sub-region only partially overlaps with a projection of the insulating structure.

5. The back contact solar cell according to claim 1, characterized in that: The material of the insulating structure is selected from at least one of silicon oxide, silicon nitride and silicon oxynitride.

6. The back contact solar cell according to claim 1, characterized in that: The insulating structure contains doping elements.

7. The back contact solar cell according to claim 1, characterized in that: In the case where the insulating structure is located in the first transmission layer within the first stacking sub-region, the thickness of the insulating structure is 0.1 nm-20 nm.

8. The back contact solar cell according to claim 1, characterized in that: Also includes: a heat-affected structure, the heat-affected structure being located on a side of the insulating structure away from the silicon substrate, the heat-affected structure being in contact with the insulating structure, and a projection of the heat-affected structure falling within a projection of the insulating structure in a thickness direction of the silicon substrate; The second transmission layer includes a heat-affected structure and a non-heat-affected structure; The electrical conductivity of the heat-affected structure is less than the electrical conductivity of the non-heat-affected structure.

9. The back contact solar cell according to claim 1, characterized in that: The first transmission layer comprises: a stacked tunneling oxide layer and a doped polysilicon layer, wherein the tunneling oxide layer is closer to the silicon substrate than the doped polycrystalline layer; the second transmission layer comprises: a stacked intrinsic amorphous silicon layer and a doped amorphous silicon layer, wherein the intrinsic amorphous silicon layer is closer to the silicon substrate; the doping types of the doped polycrystalline layer and the doped amorphous silicon layer are different; or, The first transmission layer and the second transmission layer both include: a tunneling oxide layer and a doped polysilicon layer stacked, wherein the tunneling oxide layer in the first transmission layer and the second transmission layer is closer to the silicon substrate than the doped polysilicon layer; the doping types of the doped polysilicon layer in the first transmission layer and the second transmission layer are different; or The first transmission layer and the second transmission layer both include: an intrinsic amorphous silicon layer and a doped amorphous silicon layer stacked together, wherein the intrinsic amorphous silicon layer in the first transmission layer and the second transmission layer is closer to the silicon substrate than the doped amorphous silicon layer; and the doping types of the doped amorphous layers in the first transmission layer and the second transmission layer are different.

10. The back contact solar cell according to any one of claims 1 to 9, characterized in that: On a side close to the second conductive region in the first direction, a distance between an edge of the insulating structure and an edge of the first transmission layer is 5 nm to 50 μm.

11. The back contact solar cell according to any one of claims 1 to 9, characterized in that: In the first direction, the width of the insulating structure is 10 nm to 100 μm.

12. The back-contact solar cell according to any one of claims 1 to 9, characterized in that: The isolation region is composed of a first stacking sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacking sub-region; the second transmission layer is at least located on the second conductive region and the first stacking sub-region; or, The isolation region is composed of a first stacked sub-region adjacent to the second conductive region, an opening sub-region adjacent to the first stacked sub-region, and a second stacked sub-region adjacent to the first conductive region; the second transmission layer is located at least on the second conductive region, the first stacked sub-region and the second stacked sub-region.

13. The back contact solar cell according to any one of claims 1 to 9, characterized in that: Also includes: A weather-resistant oxide layer filled on the structure below the disconnected position of the transparent conductive layer; The mass proportion of oxygen atoms in the weather-resistant oxide layer is greater than or equal to 70%.

14. The back-contact solar cell according to any one of claims 1 to 9, characterized in that: The insulating structure is at least located between the first transmission layer and the second transmission layer in the first stacking sub-region, and the thickness of the insulating structure is less than or equal to 150 nm.

15. The back-contact solar cell according to any one of claims 1 to 9, characterized in that: The insulating structure includes at least one of crystalline silicon, crystalline silicon nitride, and crystalline silicon nitride oxide.

16. The back contact solar cell according to claim 3, characterized in that: The insulating structure further includes: a protruding portion projected on the first surface along the first direction and located outside a projection of the opening sub-region; In the insulating structure, a portion where the projection on the first surface overlaps with the projection of the opening sub-region is an overlapped portion; The protruding portion and the overlapping portion have different structures.

17. The back contact solar cell according to claim 16, characterized in that: The material properties of the protruding portion and the overlapping portion are different; and / or, The protruding portion and the overlapping portion have different thicknesses.

18. The back-contact solar cell according to any one of claims 1 to 9, characterized in that: The insulating structure between the first transmission layer and the second transmission layer in the first stacked sub-region includes: a silicon nitride layer and a silicate glass layer stacked in layers, and the silicate glass layer is close to the silicon substrate.

19. The back-contact solar cell according to any one of claims 1 to 9, characterized in that: Along the thickness direction of the silicon substrate, the insulating structure includes: a third region and a fourth region, the third region being closer to the silicon substrate than the fourth region; The degree of crystallization of the fourth region is greater than that of the third region.

20. The back-contact solar cell according to any one of claims 1 to 9, characterized in that: Along the thickness direction of the silicon substrate, the insulating structure includes: a third region and a fourth region, the third region being closer to the silicon substrate than the fourth region; The number ratio of silicon atoms to nitrogen atoms in the fourth region is greater than the number ratio of silicon atoms to nitrogen atoms in the third region.

21. A method for preparing a back contact solar cell, characterized in that: include: providing a silicon substrate; The silicon substrate comprises: a first surface and a second surface opposite to each other; the first surface comprises: a first conductive region, a second conductive region and an isolation region between the first conductive region and the second conductive region; the first conductive region, the isolation region and the second conductive region are sequentially distributed in a first direction; the isolation region comprises: a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region; forming a first transmission layer on the first conductive region and the isolation region; Modifying the first transmission layer at least located in the first stacking sub-region to convert the first transmission layer at least located in the first stacking sub-region into an insulating structure; and / or forming an insulating structure on the first transmission layer at least located in the first stacking sub-region; in the first direction, the insulating structure is farther away from the second conductive region than the first transmission layer; A second transmission layer is formed at least on the second conductive region and the first stacked sub-region; the second transmission layer is located on a side of the insulating structure away from the silicon substrate; the first transmission layer and the second transmission layer have different conductivity types; A transparent conductive layer is formed on a side of the first transmission layer and the second transmission layer away from the silicon substrate and is disconnected in the opening sub-region.

22. The method for preparing a back contact solar cell according to claim 21, characterized in that: The forming of the first transmission layer comprises: Sequentially forming a first transmission layer and a mask layer as a whole layer on the first surface of the silicon substrate; Using laser to irradiate the portion of the mask layer located on the second conductive region, and wet-treating the portion so that the second conductive region is exposed, and retaining the mask layer and the first transmission layer located on the first conductive region and the isolation region; The step of forming an insulating structure on the first transmission layer at least in the first stacking sub-region comprises: The portion of the mask layer at least located in the first stacking sub-region is irradiated with laser, so that the mask layer at least located in the first stacking sub-region is modified to obtain at least a partial insulating structure.

23. A photovoltaic module, characterized in that: include: A back-contact solar cell as claimed in any one of claims 1 to 19.

24. A method for preparing a back contact solar cell, characterized in that: include: providing a silicon substrate; The silicon substrate comprises: a first surface and a second surface opposite to each other; the first surface comprises: a first conductive region, a second conductive region and an isolation region between the first conductive region and the second conductive region; the first conductive region, the isolation region and the second conductive region are sequentially distributed in a first direction; the isolation region comprises: a first stacked sub-region adjacent to the second conductive region and an opening sub-region adjacent to the first stacked sub-region; a first transmission layer is formed on the first conductive region and the isolation region; preparing a second transmission layer on the second conductive region and the first transmission layer; The first transmission layer and the second transmission layer have different conductivity types; Using laser to irradiate the position of the second transmission layer located in the isolation region, so that the first transmission layer and the second transmission layer located in the local position of the isolation region are co-doped to form an insulating structure; the laser irradiation width is less than or equal to the width of the isolation region; the direction of the width is parallel to the first direction; A transparent conductive layer is formed on a side of the first transmission layer and the second transmission layer away from the silicon substrate and is disconnected in the opening sub-region.

Images