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 back contact solar cell includes: a silicon substrate; the first surface of the silicon substrate comprises a first conductive region, a second conductive region and a lamination region located between the first conductive region and the second conductive region; the first transmission layer is located on the first conductive region and the lamination region; the second transmission layer is located on the second conductive region and the lamination region, and in the lamination region, the second transmission layer is located on the side, away from the silicon substrate, of the first transmission layer; in the lamination area, the side surface, close to the second conductive area, of the first transmission layer has a first concave-convex morphology, and the side surface, close to the first conductive area, of the second transmission layer has a second concave-convex morphology; the first concave-convex morphology is different from the second concave-convex morphology. The passivation effect of the junction, close to the second conductive region, of the first transmission layer is good, and the power generation efficiency of the back contact solar cell is improved.

Description

Technical Field

[0001] 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

[0002] 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.

[0003] The two conductive types of transport layers in the back-contact solar cell are located on the same side of the silicon substrate. Therefore, a stacking region is usually set between the two conductive regions, and an opening is set in the stacking region to reduce the risk of leakage.

[0004] However, the passivation effect of the stacked region in back-contact solar cells is poor, which affects the power generation efficiency of the cells. Summary of the invention

[0005] 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 passivation effect of a stacked region in existing back-contact solar cells.

[0006] In a first aspect of the present invention, a back-contact solar cell is provided, comprising: 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 a stacked region located between the first conductive region and the second conductive region; the direction in which the first conductive region, the stacked region, and the second conductive region are sequentially distributed is a first direction;

[0007] A first transmission layer, located on the first conductive region and the stacked region;

[0008] a second transmission layer, located on the second conductive region and the stacked region, and in the stacked region, at least a portion of 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;

[0009] In the stacked area: the side of the first transmission layer close to the second conductive area has a first concave-convex morphology extending along the second direction, the side of the second transmission layer close to the first conductive area has a second concave-convex morphology extending along the second direction, and the first concave-convex morphology is different from the second concave-convex morphology; the second direction intersects with the first direction, and both are perpendicular to the direction where the thickness of the silicon substrate is located.

[0010] In the present application, the second transmission layer covers the first transmission layer, that is, the second transmission layer is prepared after the first transmission layer is prepared. In the stacking area, the first concave-convex morphology is different from the second concave-convex morphology. Because the two morphologies are different, the film layers grown on the two different morphologies have randomness, which can better cover the underlying layer structure, thereby improving the passivation effect of the stacking area and improving the power generation efficiency of the solar cell.

[0011] Optionally, the first concave-convex morphology is different from the second concave-convex morphology, including: the concave-convex amplitude of the first concave-convex morphology is different from the concave-convex amplitude of the second concave-convex morphology, and / or the concave-convex frequency of the first concave-convex morphology is different from the concave-convex frequency of the second concave-convex morphology.

[0012] The difference between the first concave-convex morphology and the second concave-convex morphology is refined into the difference between the concave-convex amplitude of the first concave-convex morphology and the concave-convex amplitude of the second concave-convex morphology, and / or the difference between the concave-convex frequency of the first concave-convex morphology and the concave-convex frequency of the second concave-convex morphology. Through the concave-convex amplitude and / or concave-convex frequency, it is easy to achieve different first concave-convex morphology and second concave-convex morphology from a process point of view.

[0013] Optionally, the concavo-convex amplitude of the first concavo-convex profile is different from the concavo-convex amplitude of the second concavo-convex profile, including:

[0014] In the first direction, the concavo-convex amplitude of the first concavo-convex topography is smaller than the concavo-convex amplitude of the second concavo-convex topography;

[0015] The concave-convex frequency of the first concave-convex shape is different from the concave-convex frequency of the second concave-convex shape, including:

[0016] In the second direction, the concavo-convex frequency of the first concavo-convex topography is greater than the concavo-convex frequency of the second concavo-convex topography.

[0017] In the present application, the second transmission layer is covered on the first transmission layer, that is, the second transmission layer is prepared after the first transmission layer is prepared. First, the first concavo-convex morphology of the side of the first transmission layer close to the second conductive area has a smaller concavo-convex amplitude and / or a larger concavo-convex frequency, the side of the first transmission layer close to the second conductive area is relatively flat, and / or more regular and regular, and the second transmission layer formed thereon has a better film quality, and thus the passivation effect at the junction of the first transmission layer close to the second conductive area or the junction of the second conductive area and the stacking area is better, which improves the passivation effect of the first transmission layer close to the junction of the second conductive area in the back contact solar cell, and can improve the power generation efficiency of the back contact solar cell; second, the first transmission layer under the side of the second transmission layer close to the first conductive area can provide good passivation performance, the second concavo-convex morphology of the side of the second transmission layer close to the first conductive area has a larger concavo-convex amplitude and / or a smaller concavo-convex frequency, has a larger specific surface area, and / or is more irregular, which is conducive to further increasing the light trapping effect of the boundary area between the first conductive area and the stacking area, and improves the utilization rate of light by the silicon substrate, It also improves the power generation efficiency of the back-contact solar cell; third, the shape of the first concave-convex morphology on the side of the first transmission layer close to the second conductive area is relatively regular with highs and lows. When a passivation layer or a second transmission layer or a transparent conductive layer is grown and deposited on the side of the first transmission layer close to the second conductive area, the quality of the film formation of the above-mentioned film layers is good, relatively uniform and neat, especially when vapor deposition such as CVD (chemical vapor deposition) is used for deposition. The first concave-convex morphology with regular shape has a regular effect on the atmosphere in the vapor deposition, making the distribution of the atmosphere in the space of the area more uniform, and will not disrupt the atmosphere environment due to irregular obstructions, so that the area can better produce and deposit the above-mentioned film layers; fourth, the first concave-convex morphology on the side of the first transmission layer close to the second conductive area and the second concave-convex morphology on the side of the second transmission layer close to the first conductive area both have regular shapes with ups and downs. The above-mentioned regular shapes located at the edge can also provide a larger error space for the subsequent graphic accuracy, thereby improving the process yield.

[0018] Optionally, in a boundary region between the stacked region and the second conductive region, the second transmission layer covers a side surface of the first transmission layer.

[0019] Optionally, the first concavo-convex morphology includes: a first sub-concavo-convex morphology and a second sub-concavo-convex morphology; along the first direction, one of the second conductive regions includes a first end and a second end opposite to each other;

[0020] The first sub-concave-convex topography is adjacent to the first end, and the second sub-concave-convex topography is adjacent to the second end;

[0021] The first sub-concave-convex topography and the second sub-concave-convex topography have different concave-convex amplitudes.

[0022] Optionally, the back-contact solar cell further comprises: a transparent conductive layer, the transparent conductive layer being arranged at least on the first transmission layer of the first conductive region and on the second transmission layer of the second conductive region;

[0023] The transparent conductive layer has a disconnected opening, and the disconnected opening is at least arranged on the stacked region.

[0024] Optionally, the back contact solar cell further comprises: a transparent conductive layer, the transparent conductive layer being arranged on the first transmission layer of the first conductive region, on the second transmission layer of the second conductive region, and on the second transmission layer of the stacked region; wherein, at a local position of the stacked region, the transparent conductive layer and the second transmission layer have a disconnection opening;

[0025] The second transmission layer includes opposite third and fourth ends at one of the openings along the first direction;

[0026] The side surface of the third end and the side surface of the fourth end both have a third concave-convex morphology, and the third concave-convex morphology is different from the first concave-convex morphology and the second concave-convex morphology.

[0027] Optionally, the third concavo-convex topography is different from the first concavo-convex topography and the second concavo-convex topography, and includes:

[0028] The concavo-convex amplitude of the third concavo-convex profile is different from the concavo-convex amplitude of the first concavo-convex profile and the concavo-convex amplitude of the second concavo-convex profile;

[0029] And / or, the concavo-convex frequency of the third concavo-convex morphology is different from the concavo-convex frequency of the first concavo-convex morphology and the concavo-convex frequency of the second concavo-convex morphology.

[0030] Optionally, the first concave-convex topography is formed by a first laser, and the second concave-convex topography is formed by a second laser;

[0031] The spot overlap rate of the first laser is greater than the spot overlap rate of the second laser.

[0032] Optionally, the power density of the first laser is greater than or equal to the power density of the second laser.

[0033] Optionally, the spot size of the first laser is larger than the spot size of the second laser.

[0034] Optionally, the first transmission layer has a third surface and a fourth surface opposite to each other, the third surface is a surface of the first transmission layer away from the silicon substrate, and the fourth surface is a surface of the first transmission layer close to the silicon substrate;

[0035] The second transmission layer has a fifth surface and a sixth surface opposite to each other, the fifth surface is a surface of the second transmission layer away from the silicon substrate, and the sixth surface is a surface of the second transmission layer close to the silicon substrate;

[0036] Wherein, in the thickness direction of the silicon substrate, the distance from the third surface of the first transmission layer to the silicon substrate is greater than the distance from the fifth surface of the second transmission layer to the fourth surface of the first transmission layer.

[0037] Optionally, in the first direction, the width of the second conductive region is greater than the width of the first conductive region.

[0038] Optionally, in the first direction, the width of the first conductive region is greater than or equal to the spot size of the second laser.

[0039] Optionally, the first concave-convex topography is formed by a first laser, the second concave-convex topography is formed by a second laser, and the third concave-convex topography is formed by a third laser;

[0040] The spot overlap rate of the third laser light is different from the spot overlap rate of the first laser light, and the spot overlap rate of the third laser light is different from the spot overlap rate of the second laser light.

[0041] A second aspect of the present invention provides a method for preparing a back-contact solar cell, comprising:

[0042] A silicon substrate is provided; the silicon substrate comprises: a first surface and a second surface opposite to each other; the first surface comprises: the first surface comprises: a first conductive region, a second conductive region and a stacked region located between the first conductive region and the second conductive region; the direction in which the first conductive region, the stacked region and the second conductive region are sequentially distributed is a first direction;

[0043] forming a first transmission layer on the first surface;

[0044] Using a first laser to process a portion of the first transmission layer located on the second conductive region to expose the second conductive region;

[0045] forming 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;

[0046] Using a second laser to remove the portion of the second transmission layer located on the first conductive region, so that the first transmission layer is exposed;

[0047] In the stacking area, at least a portion of the second transmission layer is located on a side of the first transmission layer away from the silicon substrate; in the stacking area: the side of the first transmission layer close to the second conductive area has a first concave-convex morphology extending along a second direction, and the side of the second transmission layer close to the first conductive area has a second concave-convex morphology extending along the second direction, and the first concave-convex morphology is different from the second concave-convex morphology; the second direction intersects with the first direction, and both are perpendicular to the direction where the thickness of the silicon substrate is located.

[0048] Optionally, the power density of the first laser is greater than or equal to the power density of the second laser.

[0049] Optionally, the method for preparing the back contact solar cell further includes:

[0050] forming a whole transparent conductive layer on the first transmission layer and the second transmission layer on a side away from the silicon substrate;

[0051] A third laser is used to form openings at local positions of the transparent conductive layer and the second transmission layer in the stacked layer region.

[0052] A third aspect of the present invention provides a photovoltaic module, comprising: a plurality of any of the aforementioned back-contact solar cells.

[0053] The above-mentioned back-contact solar cell and its preparation method and photovoltaic module have the same or similar beneficial effects, and will not be described again here to avoid repetition. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0055] Figure 1 A partial structural schematic diagram of a back-contact solar cell in an embodiment of the present invention is shown;

[0056] Figure 2 A schematic diagram of a local structure of a first concave-convex morphology in an embodiment of the present invention is shown;

[0057] Figure 3 A schematic diagram of a partial structure of a second concave-convex topography in an embodiment of the present invention is shown;

[0058] Figure 4 A partial structural schematic diagram of another back-contact solar cell in an embodiment of the present invention is shown;

[0059] Figures 5 to 11 A schematic diagram of the structure of the process steps of a back-contact solar cell in an embodiment of the present invention is shown.

[0060] Description of the accompanying drawings:

[0061] 1-silicon substrate, 2-tunneling oxide layer, 3-N-type doped polysilicon layer, 4-dielectric layer, 5-disconnection position, 6-intrinsic amorphous silicon layer, 7-P-type doped amorphous silicon layer, 8-front passivation layer, 9-front anti-reflection layer, 10-notch, 11-transparent conductive layer, 12-opening, 13-electrode. DETAILED DESCRIPTION

[0062] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] The present invention provides a back contact solar cell, referring to Figure 1 The back contact solar cell comprises: a silicon substrate 1, a first transmission layer and a second transmission layer. The silicon substrate 1 comprises: a first surface and a second surface opposite to each other, the first surface can be its backlight surface, and the second surface is a 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 11 The upper surface of the silicon substrate 1 is the first surface (refer to Figure 5 B), the lower surface is the second surface (refer to Figure 5 As shown in F in FIG. 1 ), the first surface includes: a first conductive region, a second conductive region, and a laminated region located between the first conductive region and the second conductive region. Figure 1 In the first surface, the area on the left side of the dotted line L1 is the first conductive area, the area between the dotted line L1 and the dotted line L2 is the stacked area, and the area on the right side of the dotted line L2 is the second conductive area. The direction in which the first conductive area, the stacked area, and the second conductive area are sequentially distributed on the first surface is the first direction M.

[0064] The first transmission layer is located on the first conductive area and the stacking area; the second transmission layer is located on the second conductive area and the stacking area, that is, the first transmission layer is located on the area on the left side of the dotted line L2 on the first surface. The second transmission layer is located on the area on the right side of the dotted line L1 on the first surface, and in the stacking area from the dotted line L1 to the dotted line L2, at least part of the second transmission layer is farther away from the silicon substrate than the first transmission layer, that is, in the process of forming a back-contact solar cell, the first transmission layer is formed first and then the second transmission layer is formed. The first transmission layer and the second transmission layer have different conductivity types, one of which is an N-type transmission layer and the other is a P-type transmission layer. Which one is the N-type transmission layer and which one is the P-type transmission layer is not specifically limited. There is no limitation on the specific materials of the N-type transmission layer and the P-type transmission layer.

[0065] For example, the first transmission layer may be an N-type transmission layer, and the second transmission layer may be a P-type transmission layer. The first transmission layer may include a tunneling oxide layer 2 and an N-type doped polysilicon layer 3. The second transmission layer may include an intrinsic amorphous silicon layer 6 and a P-type doped amorphous silicon layer 7.

[0066] It should be noted that the dotted line L1 to the dotted line L2 mentioned in the entire application and the drawings is only for distinguishing different areas and does not exist in the actual back-contact solar cell.

[0067] In the Overlay area: Refer to Figure 2 , the side surface of the first transmission layer close to the second conductive region has a first concave-convex morphology extending along the second direction Q, that is, Figure 1 In the embodiment, the first transmission layer has a first concave-convex shape extending along the second direction Q on the side of the dotted line L2. Figure 3 , the side surface of the second transmission layer close to the first conductive region has a second concave-convex morphology extending along the second direction Q, that is, Figure 1 In the figure, the second transmission layer has a second concave-convex morphology extending along the second direction Q on the side where the dotted line L1 is located. The first concave-convex morphology is different from the second concave-convex morphology. The second direction Q intersects with the first direction M, and both are perpendicular to the direction N where the thickness of the silicon substrate 1 is located. In the present application, the second transmission layer is covered on the first transmission layer, that is, the second transmission layer is prepared after the first transmission layer is prepared. In the stacking area, the first concave-convex morphology is different from the second concave-convex morphology. Because the morphologies of the two are different, the film layers grown on the two different morphologies are random, which can better cover the underlying layer structure, thereby improving the passivation effect of the stacking area and improving the power generation efficiency of the solar cell.

[0068] It should be noted that the difference between the first concavo-convex morphology and the second concavo-convex morphology refers to that various parameters related to the shape of the first concavo-convex morphology and various parameters related to the shape of the second concavo-convex morphology are not equal.

[0069] Optional, see Figure 2 and Figure 3 The first concavo-convex shape mentioned above is different from the second concavo-convex shape, including: the concavo-convex amplitude R1 of the first concavo-convex shape is different from the concavo-convex amplitude R2 of the second concavo-convex shape, and / or the concavo-convex frequency of the first concavo-convex shape is different from the concavo-convex frequency of the second concavo-convex shape. The concavo-convex amplitude here refers to: Figure 2 and Figure 3 , the first concave-convex shape includes peaks and troughs in the first direction M, and the concave-convex amplitude R1 of the first concave-convex shape refers to the distance between a peak and a trough of the first concave-convex shape here in the first direction M, or it can be the average value of the distance between multiple peaks and multiple troughs of the first concave-convex shape in the first direction M. Here, the determination method of the concave-convex amplitude R2 of the second concave-convex shape is similar to this. The concave-convex frequency here refers to the number of concave points (troughs) and / or convex points (peaks) in the first concave-convex shape and the number of concave points and / or convex points in the second concave-convex shape within the same size along the second direction Q, or the number of concave points and / or convex points in the first concave-convex shape within the unit size along the second direction Q, and the number of concave points or convex points in the second concave-convex shape. If the number is more, the concave-convex frequency is greater. It should be noted that the method for determining the concave-convex frequency of the first concave-convex shape is the same as the method for determining the concave-convex frequency of the second concave-convex shape. The difference between the first concave-convex morphology and the second concave-convex morphology is refined into the difference between the concave-convex amplitude R1 of the first concave-convex morphology and the concave-convex amplitude R2 of the second concave-convex morphology, and / or the concave-convex frequency of the first concave-convex morphology and the concave-convex frequency of the second concave-convex morphology. Through the concave-convex amplitude and / or concave-convex frequency, it is easy to achieve different first concave-convex morphologies and second concave-convex morphologies from a process point of view.

[0070] Optional, see Figure 2 and Figure 3 , the concave-convex amplitude R1 of the first concave-convex morphology is different from the concave-convex amplitude R2 of the second concave-convex morphology, including: in the first direction M, the concave-convex amplitude R1 of the first concave-convex morphology is smaller than the concave-convex amplitude R2 of the second concave-convex morphology; the concave-convex frequency of the first concave-convex morphology is different from the concave-convex frequency of the second concave-convex morphology, including: in the second direction Q, the concave-convex frequency of the first concave-convex morphology is greater than the concave-convex frequency of the second concave-convex morphology. For example, Figure 2 and Figure 3 In the figure, along the second direction Q, the distance between adjacent troughs or adjacent peaks in the first concave-convex topography is d2, and along the second direction Q, the distance between adjacent troughs or adjacent peaks in the second concave-convex topography is d3, d2<d3, then, along the second direction Q, within the same size, the number of troughs or peaks in the first concave-convex topography is greater than the number of troughs (concave points) or peaks (convex points) in the second concave-convex topography, and thus the concave-convex frequency of the first concave-convex topography is greater, and the distribution of the first concave-convex topography is more regular or more regular.

[0071] Specifically, the second transmission layer is covered on the first transmission layer, that is, the second transmission layer is prepared after the first transmission layer is prepared. First, the first concave-convex morphology of the side of the first transmission layer close to the second conductive area has a smaller concave-convex amplitude R1 and / or a larger concave-convex frequency, the side of the first transmission layer close to the second conductive area is relatively flat, and / or more regular and regular, and the second transmission layer formed thereon has a better film quality, and thus the passivation effect at the junction of the first transmission layer close to the second conductive area or the junction of the second conductive area and the stacking area is better, which improves the passivation effect of the first transmission layer close to the junction of the second conductive area in the back contact solar cell, and can improve the power generation efficiency of the back contact solar cell; second, the first transmission layer under the side of the second transmission layer close to the first conductive area can provide good passivation performance, the second concave-convex morphology of the side of the second transmission layer close to the first conductive area has a larger concave-convex amplitude and / or a smaller concave-convex frequency, has a larger specific surface area, and / or is more irregular, which is conducive to further increasing the light trapping effect of the boundary area between the first conductive area and the stacking area, and improves the use of light by the silicon substrate. rate, and also improves the power generation efficiency of the back-contact solar cell; third, the shape of the first concave-convex morphology of the side of the first transmission layer close to the second conductive area is relatively regular with highs and lows. When the passivation layer or the second transmission layer or the transparent conductive layer is grown and deposited on the side of the first transmission layer close to the second conductive area, the quality of the film formation of the above-mentioned film layers is good, relatively uniform and neat, especially when vapor deposition such as CVD (chemical vapor deposition) is used for deposition, the first concave-convex morphology with regular shape has a regular effect on the atmosphere in the vapor deposition, so that the distribution of the atmosphere in the space of the area is more uniform, and the atmosphere environment will not be disrupted due to irregular blocking, so that the area can better produce and deposit the above-mentioned film layers; fourth, the first concave-convex morphology of the side of the first transmission layer close to the second conductive area and the second concave-convex morphology of the side of the second transmission layer close to the first conductive area both have regular shapes with ups and downs. The above-mentioned regular shapes located at the edge can also provide a larger error space for the subsequent graphic accuracy, thereby improving the process yield.

[0072] Optionally, the first concave-convex morphology here is formed by a first laser, and the second concave-convex morphology is formed by a second laser, and the spot overlap rate of the first laser is greater than the spot overlap rate of the second laser. Here, the spot overlap rate of the first laser is greater than the spot overlap rate of the second laser, thereby forming a concave-convex amplitude R1 of the first concave-convex morphology that is smaller than a concave-convex amplitude R2 of the second concave-convex morphology, and / or a concave-convex frequency of the first concave-convex morphology that is greater than the concave-convex frequency of the second concave-convex morphology.

[0073] Optional, see Figure 1 and Figure 4In the interface area between the stacked area and the second conductive area, the second transmission layer covers the side of the first transmission layer, and the second transmission layer covers the side of the first transmission layer in the interface area, that is, Figure 1 In the figure, at the position of the dotted line L2, the second transmission layer covers the side of the first transmission layer. The second transmission layer covers the junction area more comprehensively, and has a better passivation effect at the junction of the first transmission layer close to the second conductive area or at the junction of the second conductive area and the stacked area, which improves the passivation effect of the junction of the first transmission layer close to the second conductive area in the back contact solar cell, and can improve the power generation efficiency of the back contact solar cell.

[0074] Optional, see Figure 1 and Figure 4 Along the first direction M, the width d1 of the stacking area is 20μm to 400μm. If d1 is too small, the electrical isolation effect is poor and a short circuit risk may be introduced. If d1 is too large, more carrier collection dead zones are introduced. When d1 is within the above range, not only the electrical isolation effect is good, but also the introduced carrier collection dead zones are small.

[0075] For example, along the first direction M, the width d1 of the stacking region may be 20 μm, 40 μm, 50 μm, 100 μm, 80 μm, 120 μm, 150 μm, 180 μm, 200 μm, 250 μm, 280 μm, 300 μm, 350 μm, 330 μm, or 400 μm.

[0076] Optional, see Figure 4 The first concavo-convex morphology includes: a first sub-concavo-convex morphology and a second sub-concavo-convex morphology; along the first direction M, a second conductive region includes a first end and a second end opposite to each other; Figure 4 In the figure, the portion between L2 and L2 on the first surface is a second conductive region, and the positions of the two L2 are the first end and the second end of the second conductive region, the first end is any one of the two L2, and the second end is the other of the two L2. The first sub-concave-convex morphology is adjacent to the first end, and the second sub-concave-convex morphology is adjacent to the second end; the concave-convex amplitude of the first sub-concave-convex morphology and the second sub-concave-convex morphology are different, that is, the concave-convex amplitude R1 of the first sub-concave-convex morphology and the second sub-concave-convex morphology is different, but both R1 are smaller than R2. For a second conductive region, the two R1s at both ends can be different, the processing window is larger, and the two R1s are still small. The two sides of the first transmission layer close to the second conductive region are relatively flat, and the second transmission layer formed thereon has a better film quality, and then the passivation effect at the junction of the first transmission layer close to the second conductive region or the junction of the second conductive region and the stacking region is better, which improves the passivation effect at the junction of the first transmission layer close to the second conductive region in the back contact solar cell, and can improve the power generation efficiency of the back contact solar cell.

[0077] It should be noted that, for a second conductive region, when the two R1 at the two ends are different, the difference between the two is not specifically limited. For a second conductive region, the two R1 at the two ends may also be the same.

[0078] Optionally, the back contact solar cell further includes: a transparent conductive layer, which is at least arranged on the first transmission layer of the first conductive region and the second transmission layer of the second conductive region; wherein the transparent conductive layer has a disconnection opening, which is mainly used to play a good role in electrical isolation to avoid short circuit, and the disconnection opening is at least arranged on the laminated region. Below the disconnection opening, the second transmission layer and the first transmission layer can be continuously distributed, and the disconnection opening here can be formed by etching with an etching paste. The relative relationship between the size of the disconnection opening and the size of the laminated region is not specifically limited, and can be equal, or the disconnection opening is larger than the laminated region, or the disconnection opening is smaller than the laminated region.

[0079] Optional, see Figure 1 , the back contact solar cell also includes: a transparent conductive layer 11, located on the first transmission layer of the first conductive region and the second transmission layer of the second conductive region and the second transmission layer of the stacking region; the transparent conductive layer 11 and the second transmission layer have a disconnection opening 12 at a local position in the stacking region, and the opening 12 can play a good role in electrical isolation and avoid short circuit. Along the first direction M, the second transmission layer includes a third end and a fourth end at an opening; the side of the third end and the side of the fourth end both have a third concave-convex morphology extending along the second direction Q; in the first direction M, the difference between the concave-convex amplitude of the third concave-convex morphology of the side of the third end and the concave-convex amplitude of the third concave-convex morphology of the side of the fourth end is less than or equal to 5% of the concave-convex amplitude of the third concave-convex morphology of the side of either the side of the third end or the side of the fourth end. Here, the third end is any end of the second transmission layer in an opening along the first direction M, and the fourth end is the other end of the second transmission layer in an opening along the first direction M. The difference between the concavo-convex amplitude of the third concavo-convex topography on the side of the third end and the concavo-convex amplitude of the third concavo-convex topography on the side of the fourth end is less than or equal to 5% of the concavo-convex amplitude of the third concavo-convex topography on the side of either the third end or the fourth end, indicating that the difference between the concavo-convex amplitude of the third concavo-convex topography on the side of the third end and the concavo-convex amplitude of the third concavo-convex topography on the side of the fourth end is very small and almost equal, indicating that the side patterning process parameters of the third end and the fourth end are roughly the same or the same, the process parameters can be shared in the formation process of the two, and the process is simple.

[0080] For example, the difference between the concavo-convex amplitude of the third concavo-convex topography on the side of the third end and the concavo-convex amplitude of the third concavo-convex topography on the side of the fourth end can be 5%, 4%, 4.5%, 3%, 3.5%, 2%, 2.5%, 1.5%, 0.5%, 0.3%, or 0 of the concavo-convex amplitude of the third concavo-convex topography on the side of either the third end or the fourth end.

[0081] Optionally, the third concave-convex morphology is different from the aforementioned first concave-convex morphology and the second concave-convex morphology, which means that various parameters related to the shape of the third concave-convex morphology and various parameters related to the shape of the first concave-convex morphology are not equal to each other. At the same time, various parameters related to the shape of the third concave-convex morphology and various parameters related to the shape of the second concave-convex morphology are also not equal to each other. That is, the first concave-convex morphology, the second concave-convex morphology and the third concave-convex morphology are respectively matched with corresponding requirements, which can further improve the performance of the back contact solar cell. It should be noted that the formation process of the first concave-convex morphology, the second concave-convex morphology and the third concave-convex morphology may not be in the same step, or the formation process parameters of the three may be different.

[0082] Optionally, the third concave-convex morphology is different from the first concave-convex morphology and the second concave-convex morphology, including: the concave-convex amplitude of the third concave-convex morphology is different from the concave-convex amplitude of the first concave-convex morphology, and the concave-convex amplitude of the third concave-convex morphology is also different from the concave-convex amplitude of the second concave-convex morphology; and / or, the concave-convex frequency of the third concave-convex morphology is different from the concave-convex frequency of the first concave-convex morphology, and the concave-convex frequency of the third concave-convex morphology is also different from the concave-convex frequency of the second concave-convex morphology. The different concave-convex morphologies are refined into different concave-convex amplitudes and / or different concave-convex frequencies, which is easy to control from a process point of view and is easy to form the first concave-convex morphology, the second concave-convex morphology and the third concave-convex morphology with different morphologies. The definitions of the concave-convex amplitude and concave-convex frequency here can refer to the corresponding definitions mentioned above. In order to avoid repetition, they will not be repeated here.

[0083] Optionally, the spot overlap rate of the third laser forming the opening 12 is different from that of the first laser, and the spot overlap rate of the third laser is different from that of the second laser. Therefore, the second transmission layer formed at an opening includes a third concave-convex shape extending along the second direction Q formed on the sides of the relative third end and the fourth end, which is different from the shape of the first concave-convex shape, and the shape of the third concave-convex shape is also different from the shape of the second concave-convex shape.

[0084] Optionally, the size of the spot of the first laser is larger than that of the spot of the second laser, where the size of the spot of the second laser can be its length or its width, that is, the length and width of the spot of the second laser are correspondingly smaller than the length and width of the spot of the first light, thereby forming a first concave-convex morphology with a concave-convex amplitude R1 smaller than a second concave-convex morphology with a concave-convex amplitude R2, and / or a first concave-convex morphology with a concave-convex frequency greater than a second concave-convex morphology with a concave-convex frequency.

[0085] Optional, see Figure 1 , the first transmission layer has a third surface and a fourth surface relative to each other, the third surface is the surface of the first transmission layer away from the silicon substrate 1, and the fourth surface is the surface of the first transmission layer close to the silicon substrate 1; the second transmission layer has a fifth surface and a sixth surface relative to each other, the fifth surface is the surface of the second transmission layer away from the silicon substrate 1, and the sixth surface is the surface of the second transmission layer close to the silicon substrate. In the thickness direction N of the silicon substrate 1, the distance d4 from the third surface of the first transmission layer to the silicon substrate 1 is greater than the distance d5 from the fifth surface of the second transmission layer to the fourth surface of the first transmission layer, that is, d4>d5. Specifically, where the stacking area is close to the second conductive area, the area has the function of photoelectric conversion and / or hot spot prevention, and where the stacking area is close to the first conductive area, the area actually has no photoelectric conversion and / or hot spot prevention function. Therefore, especially where the stacking area is close to the second conductive area, it is necessary to specially consider the film forming quality of the area. The distance d4 from the third surface of the first transmission layer to the surface of the silicon substrate 1 of the second conductive area is longer than the distance d5 from the fifth surface of the second transmission layer to the fourth surface of the first transmission layer, thereby improving the film quality of the stacking area close to the second conductive area, improving the passivation effect and / or hot spot prevention effect to ensure the power generation efficiency of the solar cell, and at the same time When the concave-convex morphology of the side of the first transmission layer near the second conductive area in the stacked area has a smaller concave-convex amplitude and / or a larger concave-convex frequency, when the passivation layer or the second transmission layer or the transparent conductive layer is grown and deposited on the side, the quality of the film formation of the above-mentioned film layers is better, more uniform and neat, especially when vapor deposition such as CVD (chemical vapor deposition) is used for deposition, the first concave-convex morphology has little effect on the atmosphere in the vapor deposition, making the distribution of the atmosphere in the space of the area more uniform, and will not disrupt the atmosphere environment due to excessive concave-convex amplitude and / or too small concave-convex frequency, so that the area can better produce and deposit the above-mentioned film layer, improve the passivation effect, and ultimately improve the power generation efficiency of the solar cell. Here, there is no specific limit on how much larger d4 is than d5.

[0086] Optionally, in the first direction M, the width of the second conductive region is greater than the width of the first conductive region, referring to Figure 4In the first surface of the silicon substrate 1, the area corresponding to the left side of the opening from the left side of L1 to the leftmost side of the transparent conductive layer is the first conductive area, and the size of the first conductive area in the first direction M is the width of the first conductive area. In the first surface of the silicon substrate 1, the area between the two L2 is the second conductive area, and the size of the second conductive area in the first direction M is the width of the second conductive area. Because the materials of the transmission layers on the first conductive area and the second conductive area are different, in order to improve the production efficiency, different lasers are used to process and treat the first transmission layer and the second transmission layer respectively, thereby achieving an improvement in production efficiency; in particular, the width of the second conductive area is larger, and the laser damage here can be more thoroughly removed, so that the film layer formed in this area has better quality, the film layer quality of the stacking area close to the second conductive area is improved, and the passivation effect and / or heat protection are improved. spot effect to ensure the power generation efficiency of the solar cell; in addition, the second transmission layer may contain a doped polycrystalline silicon layer, and the doped polycrystalline silicon layer is laser processed on the second conductive area. Because the doped polycrystalline silicon layer is difficult to etch, a laser with larger energy and a laser with a higher overlap rate are required to achieve a wider opening processing of the doped polycrystalline silicon layer; the first transmission layer may contain a doped amorphous silicon layer, and the doped amorphous silicon layer is laser processed on the first conductive area. Because the doped amorphous silicon layer is easier to etch, and it is necessary to consider the influence of the doped polycrystalline silicon layer under the doped amorphous silicon layer as much as possible during laser processing, a laser with smaller energy and a laser with a lower overlap rate are required to achieve a narrower opening processing of the doped amorphous silicon layer. In addition, since the processing width of the doped amorphous silicon layer does not need to be too wide, that is, a single spot is used to process the doped amorphous silicon layer, graphical processing can be achieved, thereby maximizing production efficiency.

[0087] Optionally, in the first direction M, the width of the first conductive region is greater than or equal to the spot size of the second laser. Specifically, after the second transmission layer on the first conductive region is opened using the spot of the second laser, wet etching may usually be required. The width of the opening will increase after wet etching, so the width of the first conductive region is greater than or equal to the spot size of the second laser, which is easy to implement in the process.

[0088] The present application also provides a method for preparing a back-contact solar cell, which comprises the following steps.

[0089] Step 101, providing a silicon substrate; the silicon substrate includes: a first surface and a second surface opposite to each other; the first surface includes: the first surface includes: a first conductive region, a second conductive region and a stacked region located between the first conductive region and the second conductive region; the direction in which the first conductive region, the stacked region and the second conductive region are distributed in sequence is a first direction.

[0090] The silicon substrate here refers to the above description, and in order to avoid repetition, it will not be described again here.

[0091] Step 102: forming a first transmission layer on the first surface.

[0092] There is no specific limitation on the method of forming the first transmission layer. Figure 5 , a tunnel oxide layer 2 (SiO x ) and N-type doped polysilicon layer 3 and dielectric layer 4. The thickness of the tunnel oxide layer 2 can be 0.5nm to 5nm; the thickness of the N-type doped polysilicon layer 3 can be 30nm to 300nm; the thickness of the dielectric layer 4 is 10nm to 1000nm, and the material of the dielectric layer 4 can be SiN x (Silicon Nitride) or SiO x (silicon oxide), etc., and x in the chemical formula of the present application is greater than 0.

[0093] Step 103: Use a first laser to process a portion of the first transmission layer located on the second conductive region to expose the second conductive region.

[0094] Reference Figure 6 and Figure 7 , a first laser is used to process a portion of the first transmission layer located on the second conductive area, and then a wet process is performed to expose the second conductive area. Figure 6 and Figure 7 Reference numeral 5 indicates the disconnection position between the first transmission layer and the dielectric layer 4 .

[0095] Specifically, the first laser can be used to interrupt the dielectric layer 4 and the first transmission layer. The width of the disconnection position 5 can be 20 μm to 2000 μm, and the direction of the width is parallel to the first direction M. The first laser used for disconnection can be selected with a wavelength of 532 nm and a pulse width of picosecond type. The film layer that needs to be disconnected by the first laser is thicker, and the power of the first laser will be greater than the power of the second laser. For example, the power density of the first laser can be 200 mJ / cm 2 The power of the first laser can be in the range of 100 mJ / cm 2 Up to 500mJ / cm 2 The first laser can be a 200 μm spot with three lines to process the disconnection position 5. The overlap rate of the first laser is about 60%, and the overlap rate can be changed. The greater the power used, the lower the overlap rate can be (for example, the overlap rate of the first laser can range from 0-100%).

[0096] Then, a wet etching step is performed to remove the damaged layer caused by the first laser, and the disconnection position 5 is textured at the same time, and the remaining dielectric layer is also removed. This step can be etching the damaged layer and textured at the same time, or it can be polishing to remove the damaged layer. The basic purpose is to remove the damaged layer. Figure 2 , is a schematic diagram of the edge morphology after the first laser is disconnected and the disconnected position is wet-etched. It can be seen that the side of the first transmission layer close to the second conductive area has a first concave-convex morphology extending along the second direction Q. In the first direction M, the concave-convex amplitude of the first concave-convex morphology is R1.

[0097] Step 104: forming 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.

[0098] Reference Figure 8 , a second transmission layer is formed on the second conductive region and the first transmission layer; the first transmission layer and the second transmission layer have different conductivity types. For example, the first transmission layer may be an N-type transmission layer, and the second transmission layer may be a P-type transmission layer. The first transmission layer may include a tunneling oxide layer 2 and an N-type doped polysilicon layer 3. The second transmission layer may include an intrinsic amorphous silicon layer 6 and a P-type doped amorphous silicon layer 7.

[0099] Reference Figure 8 In this step, a front passivation layer 8 and a front anti-reflection layer 9 can be formed on the second surface of the silicon substrate. The front passivation layer 8 can be made of intrinsic amorphous silicon, or the front passivation layer 8 can be made of AlO. x The thickness of the (aluminum oxide) layer, the intrinsic amorphous silicon layer 6 and the front passivation layer 8 can all range from 3nm to 20nm. The thickness of the P-type doped amorphous silicon layer 7 can range from 3nm to 100nm. The front anti-reflection layer 9 can be made of SiN x (Silicon nitride), the thickness of which can range from 10nm to 300nm.

[0100] Step 105, using a second laser to process a portion of the second transmission layer located on the first conductive region to expose the first transmission layer; in the stacking region, at least a portion of the second transmission layer is located on a side of the first transmission layer away from the silicon substrate; in the stacking region: a side of the first transmission layer close to the second conductive region has a first concave-convex morphology extending along a second direction, a side of the second transmission layer close to the first conductive region has a second concave-convex morphology extending along the second direction, and the first concave-convex morphology is different from the second concave-convex morphology; the second direction intersects with the first direction, and both are perpendicular to the direction in which the thickness of the silicon substrate is located.

[0101] Reference Fig. 9The second transmission layer is patterned with a second laser to form a gap 10. The width of the gap 10 can be 150 μm to 200 μm, for example, 180 μm, and the direction of the width is parallel to the first direction M. The wavelength of the second laser is 532 nm, and the pulse width is picoseconds. The power density used can be 120 mJ / cm2, and the range of the second laser can be 30 mJ / cm 2 Up to 300mJ / cm 2 A single spot can be used, and the spot size can be 180μm. The spot overlap rate of the second laser is about 10%. When the spot shaping of the second laser is a rectangular spot, it is best if the spot of the second laser is tangent. Figure 4 This is an optical microscope photograph after the second laser process. It can be seen that the side of the second transmission layer close to the first conductive area has a second concave-convex morphology extending along the second direction Q; the first concave-convex morphology is different from the second concave-convex morphology; the second direction intersects with the first direction, and both are perpendicular to the direction where the thickness of the silicon substrate is located.

[0102] The first concavo-convex morphology and the second concavo-convex morphology are different here, and reference can be made to the aforementioned related records. For example, in the first direction M, the concavo-convex amplitude R1 of the first concavo-convex morphology is smaller than the concavo-convex amplitude R2 of the second concavo-convex morphology.

[0103] Here, the spot overlap rate of the first laser is greater than the spot overlap rate of the second laser, so that the concave-convex amplitude R1 of the first concave-convex shape is smaller than the concave-convex amplitude R2 of the second concave-convex shape.

[0104] Optionally, the power density of the first laser is greater than or equal to the power density of the second laser. Specifically, the total thickness of the first transmission layer and the dielectric layer 4 thereon is larger, while the thickness of the second transmission layer is smaller. Therefore, a larger power density is used to interrupt the first transmission layer and the dielectric layer 4 thereon.

[0105] Optionally, the spot of the first laser is at least one of a square spot, a circular spot, and an elliptical spot; and / or the spot of the second laser is at least one of a square spot, a circular spot, and an elliptical spot. The laser spots of the above shapes are easy to achieve the required overlap ratios.

[0106] Optionally, the spot of the first laser is a square spot, and the size of the spot is 100μm to 600μm. Further, 200μm to 520μm; the size of the square spot is within the above range, and it is easy to control the overlap rate. For example, the spot of the first laser is a square spot, and the size of the spot is 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, 365μm, 550μm, 600μm. It should be noted that the size of the spot of the first laser here can be its length or its width, that is, the length and width of the spot of the first laser are both 100μm to 600μm.

[0107] Optionally, the spot of the second laser is a square spot, and the spot size is 50μm to 300μm. Further, it can be 180μm; the size of the square spot is within the above range, and it is easy to control the overlap rate. For example, the spot of the second laser is a square spot, and the size of the spot is 50μm, 100μm, 150μm, 200μm, 250μm, 300μm, 180μm, 220μm, 280μm. It should be noted that the size of the spot of the second laser here can be its length or its width, that is, the length and width of the spot of the second laser are both 50μm to 300μm.

[0108] Optionally, the preparation method may further include: referring to Fig.10 A transparent conductive layer 11 is formed on the first transmission layer and the second transmission layer on the side away from the silicon substrate 1; Fig.11 , using a third laser, an opening 12 is formed at a local position of the transparent conductive layer 11 and the second transmission layer in the stacking area. The width of the opening 12 can be 20μm to 200μm. The transparent conductive layer 11 can play a certain role in energy level matching, and can further improve the performance of the back contact solar cell. The opening 12 here can avoid short circuits. The transparent conductive layer 11 can be coated using a PVD (physical vapor deposition) device or an RPD (reactive plasma deposition) device, and the thickness of the transparent conductive layer 11 can range from 20nm to 200nm.

[0109] Optionally, the spot overlap rate of the third laser forming the opening 12 is different from that of the first laser, and the spot overlap rate of the third laser is different from that of the second laser. Therefore, the second transmission layer formed at an opening includes a third concave-convex shape extending along the second direction Q formed on the sides of the relative third end and the fourth end, which is different from the shape of the first concave-convex shape, and the shape of the third concave-convex shape is also different from the shape of the second concave-convex shape.

[0110] It should be noted that the transparent conductive layer 11 may also be etched using an etching paste, and no opening will be formed on the second transmission layer, and the first transmission layer and the second transmission layer are continuously arranged below the opening.

[0111] Reference Figure 1 , to prepare the electrode, the electrode 13 can be prepared by screen printing, and the material of the electrode is not specifically limited.

[0112] The present application is further explained below in conjunction with specific embodiments.

[0113] Example

[0114] The first step is to wet-polish the silicon substrate. The wet-polishing scheme mainly includes two steps: cleaning and alkaline polishing.

[0115] The cleaning steps are: (1) using SC1 (standard cleaning 1) in the RCA cleaning (industrial standard wet cleaning) process for cleaning. (2) then washing with deionized water to neutralize the residual chemicals in the SC1 cleaning; alkali polishing steps: (1) KOH removes the surface damage layer caused by cutting, and the surface of the silicon substrate is polished; (2) then high-efficiency SC1 cleaning is performed; (3) SC2 (standard cleaning 2 in the industrial standard wet cleaning) is used to remove the residual metal ions; (4) finally, 5%wt (mass concentration 5%) hydrofluoric acid cleaning is performed to complete the polishing of the silicon substrate surface, and the polishing thickness of the front and back sides of the silicon substrate is 5μm to 10μm. After polishing, the surface of the silicon substrate forms a silicon substrate with different crystal orientations. 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 overlapping region located between the first conductive region and the second conductive region. The direction in which the first conductive region, the overlapping region, and the second conductive region are sequentially distributed is the first direction M.

[0116] Step 2: Refer to Figure 5 , using LPCVD equipment to deposit the first transmission layer. The first transmission layer includes a tunneling oxide layer 2 and an N-type doped polysilicon layer 3. A dielectric layer 4 is also deposited on the first transmission layer. The thickness of the tunneling oxide layer 2 can be 3nm; the thickness of the N-type doped polysilicon layer 3 can be 100nm; the thickness of the dielectric layer 4 is 300nm, and the material of the dielectric layer 4 can be silicon nitride. The specific implementation method is: first prepare the tunneling oxide layer 2 in the LPCVD equipment, then deposit polysilicon, and then prepare the N-type doped polysilicon layer 3 through the diffusion equipment.

[0117] Step 3: Refer to Figure 6 and Figure 7, a first laser is used to remove the portion of the first transmission layer located on the second conductive region and the portion of the dielectric layer 4 located on the second conductive region, so that the second conductive region is exposed. The first laser can be selected with a wavelength of 532nm and a pulse width of picosecond type. The power density of the first laser can be 200mJ / cm 2 , the overlap rate of the first laser spot is about 60%. Figure 2 , is a schematic diagram of the edge morphology after the first laser is disconnected and the disconnected position is wet-etched. It can be seen that the side of the first transmission layer close to the second conductive area has a first concave-convex morphology extending along the second direction Q. In the first direction M, the concave-convex amplitude of the first concave-convex morphology is R1.

[0118] Step 4: Refer to Figure 8 , a second transmission layer is formed on the second conductive region and the first transmission layer; the second transmission layer may include an intrinsic amorphous silicon layer 6 and a P-type doped amorphous silicon layer 7. A front passivation layer 8 and a front anti-reflection layer 9 are formed on the second surface of the silicon substrate. The front passivation layer 8 is an intrinsic amorphous silicon layer, and the thickness range of the intrinsic amorphous silicon layer 6 and the front passivation layer 8 can both be 10nm. The thickness range of the P-type doped amorphous silicon layer 7 can be 40nm. The front anti-reflection layer 9 can be made of SiN x (Silicon nitride), the thickness of which can be 50nm.

[0119] Step 5: Refer to Fig. 9 The second transmission layer is patterned with a second laser to form a gap 10, and the width of the gap 10 can be 180 μm. The wavelength of the second laser is 532 nm, the pulse width is picoseconds, and the power density used can be 120 mJ / cm 2 , the second laser uses a single spot with a spot size of 180μm. The spot overlap rate of the second laser is about 10%. Figure 4 , is an optical microscope photo after the second laser process, from which it can be seen that the side of the second transmission layer close to the first conductive region has a second concave-convex morphology extending along the second direction Q; in the first direction M, the concave-convex amplitude R1 of the first concave-convex morphology is smaller than the concave-convex amplitude R2 of the second concave-convex morphology. Among them, R2>R1, and d2<d3.

[0120] Step 6: Refer to Fig.10 A transparent conductive layer 11 is formed on the first transmission layer and the second transmission layer on the side away from the silicon substrate 1; Fig.11, using a third laser, an opening 12 is formed at a local position of the transparent conductive layer 11 and the second transmission layer in the stacking area. The width of the opening 12 can be 100μm. The transparent conductive layer 11 can be coated by a PVD device or an RPD device, and the thickness of the transparent conductive layer 11 can be in the range of 120nm. The spot overlap rate of the third laser that forms the opening 12 is different from the spot overlap rate of the first laser, and the spot overlap rate of the third laser is different from the spot overlap rate of the second laser. Therefore, the third concave-convex morphology extending along the second direction Q formed on the side of the third end and the fourth end opposite to each other at an opening of the formed second transmission layer is different from the shape of the first concave-convex morphology, and the shape of the third concave-convex morphology is also different from the shape of the second concave-convex morphology.

[0121] Step 7, refer to Figure 1 , to prepare the electrode, the electrode 13 can be prepared by screen printing.

[0122] 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.

[0123] It should be noted that the photovoltaic module and the preparation method of the back-contact solar cell have the same or similar beneficial effects as any of the aforementioned back-contact solar cells, and the three can be referenced to each other. In order to avoid repetition, they will not be described here.

[0124] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0125] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection 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 a stacked region located between the first conductive region and the second conductive region; the direction in which the first conductive region, the stacked region and the second conductive region are sequentially distributed is a first direction; A first transmission layer, located on the first conductive region and the stacked region; a second transmission layer, located on the second conductive region and the stacked region, and in the stacked region, at least a portion of 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; In the stacked area: the side of the first transmission layer close to the second conductive area has a first concave-convex morphology extending along the second direction, the side of the second transmission layer close to the first conductive area has a second concave-convex morphology extending along the second direction, and the first concave-convex morphology is different from the second concave-convex morphology; the second direction intersects with the first direction, and both are perpendicular to the direction where the thickness of the silicon substrate is located.

2. The back contact solar cell according to claim 1, characterized in that: The first concave-convex morphology is different from the second concave-convex morphology, including: the concave-convex amplitude of the first concave-convex morphology is different from the concave-convex amplitude of the second concave-convex morphology, and / or the concave-convex frequency of the first concave-convex morphology is different from the concave-convex frequency of the second concave-convex morphology.

3. The back contact solar cell according to claim 2, characterized in that: The concavo-convex amplitude of the first concavo-convex profile is different from the concavo-convex amplitude of the second concavo-convex profile, including: In the first direction, the concavo-convex amplitude of the first concavo-convex topography is smaller than the concavo-convex amplitude of the second concavo-convex topography; The concave-convex frequency of the first concave-convex shape is different from the concave-convex frequency of the second concave-convex shape, including: In the second direction, the concavo-convex frequency of the first concavo-convex topography is greater than the concavo-convex frequency of the second concavo-convex topography.

4. The back contact solar cell according to claim 1, characterized in that: In a boundary region between the stacked region and the second conductive region, the second transmission layer covers a side surface of the first transmission layer.

5. The back contact solar cell according to claim 1, characterized in that: The first concavo-convex morphology includes: a first sub-concavo-convex morphology and a second sub-concavo-convex morphology; along the first direction, one of the second conductive regions includes a first end and a second end opposite to each other; The first sub-concave-convex topography is adjacent to the first end, and the second sub-concave-convex topography is adjacent to the second end; The first sub-concave-convex topography and the second sub-concave-convex topography have different concave-convex amplitudes.

6. The back contact solar cell according to claim 1, characterized in that: Also includes: a transparent conductive layer, wherein the transparent conductive layer is at least disposed on the first transmission layer in the first conductive region and on the second transmission layer in the second conductive region; The transparent conductive layer has a disconnected opening, and the disconnected opening is at least arranged on the stacked region.

7. The back contact solar cell according to claim 1, characterized in that: Also includes: A transparent conductive layer, wherein the transparent conductive layer is disposed on the first transmission layer in the first conductive region, on the second transmission layer in the second conductive region, and on the second transmission layer in the stacked region; Wherein, at a local position of the stacked layer region, the transparent conductive layer and the second transmission layer have a disconnection opening; The second transmission layer includes opposite third and fourth ends at one of the openings along the first direction; The side surface of the third end and the side surface of the fourth end both have a third concave-convex morphology, and the third concave-convex morphology is different from the first concave-convex morphology and the second concave-convex morphology.

8. The back contact solar cell according to claim 7, characterized in that: The third concavo-convex topography is different from the first concavo-convex topography and the second concavo-convex topography, and includes: The concavo-convex amplitude of the third concavo-convex profile is different from the concavo-convex amplitude of the first concavo-convex profile and the concavo-convex amplitude of the second concavo-convex profile; And / or, the concavo-convex frequency of the third concavo-convex morphology is different from the concavo-convex frequency of the first concavo-convex morphology and the concavo-convex frequency of the second concavo-convex morphology.

9. The back-contact solar cell according to any one of claims 1 to 8, characterized in that: The first concavo-convex topography is formed by a first laser, and the second concavo-convex topography is formed by a second laser; The spot overlap rate of the first laser is greater than the spot overlap rate of the second laser.

10. The back contact solar cell according to claim 9, characterized in that: The power density of the first laser is greater than or equal to the power density of the second laser.

11. The back contact solar cell according to claim 9, characterized in that: The spot size of the first laser is larger than the spot size of the second laser.

12. The back contact solar cell according to claim 1, characterized in that: The first transmission layer has a third surface and a fourth surface opposite to each other, the third surface is a surface of the first transmission layer away from the silicon substrate, and the fourth surface is a surface of the first transmission layer close to the silicon substrate; The second transmission layer has a fifth surface and a sixth surface opposite to each other, the fifth surface is a surface of the second transmission layer away from the silicon substrate, and the sixth surface is a surface of the second transmission layer close to the silicon substrate; Wherein, in the thickness direction of the silicon substrate, the distance from the third surface of the first transmission layer to the silicon substrate is greater than the distance from the fifth surface of the second transmission layer to the fourth surface of the first transmission layer.

13. The back-contact solar cell according to any one of claims 1 to 8, characterized in that: In the first direction, the width of the second conductive region is greater than the width of the first conductive region.

14. The back contact solar cell according to claim 9, characterized in that: In the first direction, the width of the first conductive region is greater than or equal to the spot size of the second laser.

15. The back contact solar cell according to claim 7, characterized in that: The first concavo-convex topography is formed by a first laser, the second concavo-convex topography is formed by a second laser, and the third concavo-convex topography is formed by a third laser; The spot overlap rate of the third laser light is different from the spot overlap rate of the first laser light, and the spot overlap rate of the third laser light is different from the spot overlap rate of the second laser light.

16. 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: the first surface comprises: a first conductive region, a second conductive region and a stacked region located between the first conductive region and the second conductive region; the direction in which the first conductive region, the stacked region and the second conductive region are sequentially distributed is a first direction; forming a first transmission layer on the first surface; Using a first laser to process a portion of the first transmission layer located on the second conductive region to expose the second conductive region; forming 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 a second laser to process a portion of the second transmission layer located on the first conductive region to expose the first transmission layer; In the stacking area, at least a portion of the second transmission layer is located on a side of the first transmission layer away from the silicon substrate; in the stacking area: the side of the first transmission layer close to the second conductive area has a first concave-convex morphology extending along a second direction, and the side of the second transmission layer close to the first conductive area has a second concave-convex morphology extending along the second direction, and the first concave-convex morphology is different from the second concave-convex morphology; the second direction intersects with the first direction, and both are perpendicular to the direction where the thickness of the silicon substrate is located.

17. The method for preparing a back contact solar cell according to claim 16, characterized in that: Also includes: forming a whole transparent conductive layer on the side of the first transmission layer and the second transmission layer facing away from the silicon substrate; A third laser is used to form openings at local positions of the transparent conductive layer and the second transmission layer in the stacked layer region.

18. A photovoltaic module, characterized in that: include: A back-contact solar cell as claimed in any one of claims 1 to 15.

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