Back contact battery, manufacturing method thereof and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a back contact cell and a manufacturing method thereof, and a photovoltaic module, and the back contact cell comprises a first doped region and a second doped region which are located on a substrate and are spaced from each other; the passivation layer is located on the sides, away from the substrate, of the first and second doped regions; the first main grids and the second main grids are alternately arranged in the first direction, the first fine grids and the second fine grids are alternately arranged in the second direction, the first main grids and the fine grids are right opposite to the first doped region, and the second main grids and the fine grids are right opposite to the second doped region; at least part of the main grids comprise non-contact parts and at least one contact part in contact connection with the non-contact parts, the contact parts penetrate through the passivation layer and are in contact connection with the doped region, and each contact part is at least located in a gap between two adjacent same-polarity fine grids; and the main grid is the first main grid, the doped region is the first doped region and the same-polarity fine grid is the first fine grid, and / or the main grid is the second main grid, the doped region is the second doped region and the same-polarity fine grid is the second fine grid, so that the photoelectric conversion efficiency of the cell is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaics, and particularly to a back contact battery, a manufacturing method thereof, and a photovoltaic module. Background Art

[0002] With the gradual depletion of fossil energy, photovoltaic cells, as a new energy alternative, are being used more and more widely. A photovoltaic cell is a device that converts the light energy of the sun into electrical energy. The photovoltaic cell utilizes the photovoltaic effect to generate carriers, and then uses electrodes to extract the carriers, thereby facilitating the effective utilization of electrical energy. To further reduce the shading of the front surface of the photovoltaic cell by the grid lines, the research on IBC cells (Interdigitated Back Contact cells) has become more and more in-depth.

[0003] However, in addition to shading losses, the reasons affecting the photoelectric conversion efficiency of IBC cells also include: carrier recombination losses in the substrate, carrier recombination losses in highly doped film layers, and optical losses such as refractive losses of the film layers, as well as electrical losses such as resistance losses of the materials themselves, contact losses of the electrodes, contact losses between the solder ribbon and the photovoltaic cell, and virtual soldering between the solder ribbon and the IBC cell.

[0004] Therefore, further research is still needed to improve the photoelectric conversion efficiency of IBC cells. Summary of the Invention

[0005] Embodiments of the present disclosure provide a back contact battery, a manufacturing method thereof, and a photovoltaic module, which are at least beneficial to improving the photoelectric conversion efficiency of the back contact battery.

[0006] According to some embodiments of the present disclosure, on the one hand, an embodiment of the present disclosure provides a back-contact battery, including: a substrate; a first doping region and a second doping region that are located on the substrate and spaced apart from each other; a passivation layer located on a side of both the first doping region and the second doping region away from the substrate; a first main grid and a second main grid that are alternately arranged in a first direction, and a first fine grid and a second fine grid that are alternately arranged in a second direction, wherein the first fine grid is disconnected at the second main grid, the second fine grid is disconnected at the first main grid, the first main grid and the first fine grid are in contact connection and the orthographic projections of both on the substrate are located in the orthographic projection of the first doping region on the substrate, the second main grid and the second fine grid are in contact connection and the orthographic projections of both on the substrate are located in the orthographic projection of the second doping region on the substrate; at least a portion of the main grids include a non-contact portion, and at least one contact portion that is in contact connection with the non-contact portion, the contact portion penetrates through the passivation layer and is in contact connection with the doping region, and a single contact portion is at least located in the interval between adjacent two same-sex fine grids; wherein, the main grid is the first main grid, the doping region is the first doping region and the same-sex fine grid is the first fine grid, and / or, the main grid is the second main grid, the doping region is the second doping region and the same-sex fine grid is the second fine grid.

[0007] In some embodiments, a single main grid includes one non-contact portion and one contact portion, or, a single main grid includes one non-contact portion and a plurality of spaced-apart contact portions; wherein, a single contact portion is in contact connection with at least one same-sex fine grid and is at least located in two intervals between adjacent three same-sex fine grids, or, a single contact portion is only located in the interval between adjacent two same-sex fine grids.

[0008] In some embodiments, the shape of the orthographic projection of the contact portion on the substrate includes a serrated shape or a wavy shape.

[0009] In some embodiments, along the first direction, the width of the non-contact portion is a first width, the width of the layout area occupied by the contact portion is a second width, and the ratio of the second width to the first width is 0.2 to 0.5.

[0010] In some embodiments, along the first direction, the width of the layout area occupied by the contact portion is a second width, the width of the contact portion is a third width, and the ratio of the third width to the second width is 0.2 to 0.8.

[0011] In some embodiments, a single contact portion includes a plurality of sub-contact portions that are spaced apart along the second direction, and any one of the sub-contact portions penetrates through the passivation layer and is in contact connection with the doping region.

[0012] In some embodiments, a single contact portion includes a plurality of contact points arranged at intervals along the first direction and / or the second direction, and any one of the contact points penetrates the passivation layer and is in contact connection with the doped region.

[0013] In some embodiments, the orthographic projection area of the non-contact portion on the substrate is a first area, the orthographic projection area of the contact portion on the substrate is a second area, and the ratio of the second area to the first area is 0.2 to 0.5.

[0014] In some embodiments, with the surface of the substrate as a reference plane, the top surface of the contact portion protrudes from the top surface of the passivation layer.

[0015] According to some embodiments of the present disclosure, on the other hand, the present disclosure also provides a method for manufacturing a back-contact battery, including: providing a substrate; forming first and second doped regions spaced apart from each other on the substrate; forming a passivation layer on a side of both the first and second doped regions away from the substrate; forming first main grids and second main grids arranged alternately along a first direction and first fine grids and second fine grids arranged alternately along a second direction; wherein, the first fine grid is disconnected at the second main grid, the second fine grid is disconnected at the first main grid, the first main grid and the first fine grid are in contact connection and their orthographic projections on the substrate are both located in the orthographic projection of the first doped region on the substrate, the second main grid and the second fine grid are in contact connection and their orthographic projections on the substrate are both located in the orthographic projection of the second doped region on the substrate; at least a portion of the main grids include non-contact portions, and at least one contact portion in contact connection with the non-contact portions, the contact portion penetrates the passivation layer and is in contact connection with the doped region, and a single contact portion is at least located in the interval between adjacent two same-sex fine grids; wherein, the main grid is the first main grid, the doped region is the first doped region and the same-sex fine grid is the first fine grid, and / or, the main grid is the second main grid, the doped region is the second doped region and the same-sex fine grid is the second fine grid.

[0016] In some embodiments, the steps of forming the first fine grid, the second fine grid, the first main grid, and the second main grid include: printing a burn-through paste on the area of the passivation layer opposite to the contact portions of the first fine grid and the first main grid, and printing the burn-through paste on the area of the passivation layer opposite to the contact portions of the second fine grid and the second main grid; printing a non-burn-through paste on the side of the contact portion away from the substrate and on a part of the top surface of the passivation layer; performing a sintering process to form the contact portions of the first fine grid and the first main grid penetrating through the passivation layer on the first doping region, form the contact portions of the second fine grid and the second main grid penetrating through the passivation layer on the second doping region, and form the non-contact portions on the side of the contact portion away from the substrate and on a part of the top surface of the passivation layer.

[0017] In some embodiments, after forming the first fine grid and the second fine grid, the steps of forming the first main grid and the second main grid include: forming an opening in the area of the passivation layer opposite to the contact portion, the opening penetrating through the passivation layer; printing a main grid paste in the opening and on the side of the passivation layer away from the substrate; performing a sintering process to form the main grid in the opening and on the side of the passivation layer away from the substrate, and the contact portion is at least located in the opening.

[0018] According to some embodiments of the present disclosure, on the other hand, the embodiments of the present disclosure further provide a photovoltaic module, including: a battery string formed by connecting a plurality of the back contact batteries described in any one of the above, or a back contact battery formed by the manufacturing method described in any one of the above; an encapsulation adhesive film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulation adhesive film facing away from the battery string.

[0019] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages: When carriers are generated in the back-contact battery based on the photovoltaic effect, the first fine grid is used to collect the carriers generated in the first doped region, and the first main grid in contact connection with the first fine grid is used to further collect the carriers collected in the first fine grid; the second fine grid is used to collect the carriers generated in the second doped region, and the second main grid in contact connection with the second fine grid is used to further collect the carriers collected in the second fine grid. On this basis, there is still a first doped region in the interval between two adjacent same-sex fine grids, for example, between two adjacent first fine grids, and there is still a second doped region in the interval between two adjacent second fine grids. Thus, at least part of the main grids are designed to include a contact part in contact connection with the doped region and a non-contact part not in contact connection with the doped region. Then, the contact part of at least part of the first main grids will be in contact connection with the first doped region located in the interval between two adjacent first fine grids, and / or the contact part of at least part of the second main grids will be in contact connection with the second doped region located in the interval between two adjacent second fine grids, so that the carriers in the doped region located in the interval between two adjacent opposite-sex fine grids can be directly collected by the main grid, which is beneficial to shortening the transmission distance of the carriers in the doped region to the main grid, thereby reducing the transmission loss of the carriers, and thus is beneficial to improving the collection efficiency of the first main grid and / or the second main grid for the carriers, so as to improve the photoelectric conversion efficiency of the back-contact battery.

[0020] In addition, in the main grid including the contact part, the non-contact part does not penetrate the passivation layer and is only located on the side of the passivation layer away from the substrate, so the non-contact part will not be in contact connection with the doped region, and only part of the region of the main grid is in contact connection with the doped region, so as to avoid the carrier recombination caused by the large-area contact between the main grid and the doped region while improving the collection efficiency of the main grid for the carriers, so as to control the relatively small recombination loss of the carriers. Description of the Drawings

[0021] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments unless otherwise stated. The figures in the drawings do not constitute a proportional limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0022] Figure 1 It is a partial top view schematic diagram of a back-contact battery provided by an embodiment of the present disclosure; Figure 2 It is a partial enlarged top view schematic diagram of a back-contact battery provided by an embodiment of the present disclosure; Figure 3Another partial enlarged top view schematic diagram of the back contact battery provided by an embodiment of the present disclosure; Figure 4 is Figure 2 A partial cross-sectional schematic diagram of the back contact battery shown along the first cross-sectional direction AA1; Figure 5 is Figure 2 A partial cross-sectional schematic diagram of the back contact battery shown along the second cross-sectional direction BB1; Figure 6 is Figure 2 A partial cross-sectional schematic diagram of the back contact battery shown along the third cross-sectional direction CC1; Figure 7 Another partial enlarged top view schematic diagram of the back contact battery provided by an embodiment of the present disclosure; Figure 8 Another partial enlarged top view schematic diagram of the back contact battery provided by an embodiment of the present disclosure; Figure 9 Another partial cross-sectional schematic diagram of the back contact battery provided by an embodiment of the present disclosure along the second cross-sectional direction BB1; Figure 10 A partial enlarged bottom view schematic diagram of the main grid in the back contact battery provided by an embodiment of the present disclosure; Figure 11 Another partial enlarged bottom view schematic diagram of the main grid in the back contact battery provided by an embodiment of the present disclosure; Figure 12 A partial bottom view schematic diagram of the main grid in the back contact battery provided by an embodiment of the present disclosure; Figure 13 Another partial bottom view schematic diagram of the main grid in the back contact battery provided by an embodiment of the present disclosure; Figure 14 Another partial cross-sectional schematic diagram of the back contact battery provided by an embodiment of the present disclosure along the second cross-sectional direction BB1; Figure 15 Another partial bottom view schematic diagram of the main grid in the back contact battery provided by an embodiment of the present disclosure; Figure 16 A partial cross-sectional schematic diagram after forming the first doping region, the second doping region and the passivation layer in the manufacturing method of the back contact battery provided by another embodiment of the present disclosure; Figure 17 A partial cross-sectional schematic diagram after forming an opening in the passivation layer in the manufacturing method of the back contact battery provided by another embodiment of the present disclosure; Figure 18 A partial three-dimensional schematic diagram of the photovoltaic module provided by still another embodiment of the present disclosure; Figure 19 is Figure 18A partial cross-sectional schematic diagram of the photovoltaic module shown in the direction of the fourth cross-section DD1.

[0023] Description of the reference numerals: 100, substrate; 101, first doping region; 102, second doping region; 112, doping region; 103, passivation layer; 113, opening; 104, first main grid; 105, second main grid; 145, main grid; 1451, non-contact portion; 1452, contact portion; 1452a, sub-contact portion; 1452b, contact point; 106, first fine grid; 107, second fine grid; 167, same-sex fine grid; 40, back-contact cell; 41, encapsulation adhesive film; 42, cover plate; 43, conductive strip. Detailed implementation manners

[0024] As can be seen from the background art, the photoelectric conversion efficiency of the back-contact cell is beneficial to improvement.

[0025] The embodiments of the present disclosure provide a back-contact cell, a manufacturing method thereof, and a photovoltaic module. In the back-contact cell, when carriers are generated based on the photovoltaic effect, the first fine grid is used to collect the carriers generated in the first doping region, and the first main grid in contact connection with the first fine grid is used to further collect the carriers collected in the first fine grid; the second fine grid is used to collect the carriers generated in the second doping region, and the second main grid in contact connection with the second fine grid is used to further collect the carriers collected in the second fine grid. On this basis, in the interval between two adjacent same-sex fine grids, for example, between two adjacent first fine grids, there is also a first doping region, and in the interval between two adjacent second fine grids, there is also a second doping region. Thus, it is designed that at least part of the main grids include a contact portion in contact connection with the doping region and a non-contact portion not in contact connection with the doping region. Then, the contact portion of at least part of the first main grids will be in contact connection with the first doping region located in the interval between two adjacent first fine grids, and / or the contact portion of at least part of the second main grids will be in contact connection with the second doping region located in the interval between two adjacent second fine grids, so that the carriers in the doping region located in the interval between two adjacent opposite-sex fine grids can be directly collected by the main grid, which is beneficial to shortening the transmission distance of the carriers in the doping region to the main grid, thereby reducing the transmission loss of the carriers, and thus being beneficial to improving the collection efficiency of the first main grid and / or the second main grid for the carriers, so as to improve the photoelectric conversion efficiency of the back-contact cell. In addition, in the main grid including the contact portion, the non-contact portion does not penetrate the passivation layer and is only located on the side of the passivation layer away from the substrate, so the non-contact portion is not in contact connection with the doping region, and only part of the region of the main grid is in contact connection with the doping region, so as to avoid the carrier recombination caused by the large-area contact between the main grid and the doping region while improving the collection efficiency of the main grid for the carriers, so as to control the small recombination loss of the carriers.

[0026] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality of" is more than two, unless otherwise specifically defined.

[0027] Reference to "embodiment" in this text means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of the present disclosure. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0028] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: there is A, there is both A and B, and there is B. In addition, the character " / " in this text generally represents an "or" relationship between the associated objects before and after.

[0029] In the description of the embodiments of the present disclosure, the term "a plurality of" means more than two (including two). Similarly, "a plurality of groups" means more than two groups (including two groups), and "a plurality of pieces" means more than two pieces (including two pieces).

[0030] In the description of the embodiments of the present disclosure, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present disclosure.

[0031] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific situations.

[0032] In the accompanying drawings corresponding to the embodiments of the present disclosure, for better understanding and description, the thickness and area of the layers are enlarged. When describing a component (such as a layer, film, region, or substrate) being on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. Conversely, when describing a component being on the surface of another component or when the surface of one component forms or is provided with another component, it means there is no third component between the two components. In addition, when describing a component being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0033] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise specified, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / lying on" another component, it can be "directly on" the other component (i.e., on the surface of the other component with no other components therebetween), or there can be another component therebetween. In addition, when a component such as a layer, film, region, or plate is "directly located on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means there is no other component located therebetween.

[0034] The terms used in the description of the various embodiments herein are only for describing specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is also intended to include the plural form, unless the context clearly indicates otherwise. Among them, the component includes components such as layers, films, regions, or plates.

[0035] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are provided to enable readers to better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the embodiments of the present disclosure can still be implemented.

[0036] An embodiment of the present disclosure provides a solar cell, and the solar cell provided by an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0037] With reference to Figures 1 to 4, the back-contact battery includes: a substrate 100; a first doping region 101 and a second doping region 102 which are located on the substrate 100 and spaced apart from each other; a passivation layer 103, which is located on the side of both the first doping region 101 and the second doping region 102 away from the substrate 100; a first main grid 104 and a second main grid 105 which are alternately arranged along a first direction X, and a first fine grid 106 and a second fine grid 107 which are alternately arranged along a second direction Y. The first fine grid 106 is disconnected at the second main grid 105, and the second fine grid 107 is disconnected at the first main grid 104. The first main grid 104 and the first fine grid 106 are in contact connection, and their orthographic projections on the substrate 100 are both located in the orthographic projection of the first doping region 101 on the substrate 100. The second main grid 105 and the second fine grid 107 are in contact connection, and their orthographic projections on the substrate 100 are both located in the orthographic projection of the second doping region 102 on the substrate 100; at least a part of the main grids 145 includes a non-contact part 1451 and at least one contact part 1452 which is in contact connection with the non-contact part 1451. The contact part 1452 penetrates through the passivation layer 103 and is in contact connection with the doping region 112. A single contact part 1452 is at least located in the interval between two adjacent same-sex fine grids 167; wherein, the main grid 145 is the first main grid 104, the doping region 112 is the first doping region 101 and the same-sex fine grid 167 is the first fine grid 106, and / or, the main grid 145 is the second main grid 105, the doping region 112 is the second doping region 102 and the same-sex fine grid 167 is the second fine grid 107.

[0038] It should be noted that Figure 1 is a partial top view schematic diagram of a back-contact battery provided by an embodiment of the present disclosure; Figure 2 is a partial enlarged top view schematic diagram of a back-contact battery provided by an embodiment of the present disclosure; Figure 3 is another partial enlarged top view schematic diagram of a back-contact battery provided by an embodiment of the present disclosure; Figure 4 is Figure 2 a partial cross-sectional schematic diagram of the back-contact battery shown along a first cross-sectional direction AA1. Wherein, Figure 2 the first main grid 104 including the non-contact part 1451 and at least one contact part 1452 is taken as an example, Figure 3 and the second main grid 105 including the non-contact part 1451 and at least one contact part 1452 is taken as an example.

[0039] In addition, first, to clearly show the positional relationship among the first main grid 104, the second main grid 105, the first fine grid 106 and the second fine grid 107 on the substrate 100, Figure 1The first doping region 101 and the second doping region 102 on the substrate 100 are not shown, nor is the specific structure of the main gate 145 and the passivation layer shown. Different filling methods are used to draw the first main gate 104 and the second main gate 105 respectively, and a perspective drawing method is used for both the first main gate 104 and the second main gate 105 to show the connection relationship between the first main gate 104 and the first fine gate 106, and the connection relationship between the second main gate 105 and the second fine gate 107.

[0040] Second, to clearly show the positional relationship between the first doping region 101 and the second doping region 102 and the main gate 145 and the same-sex fine gate 167, Figure 2 and Figure 3 different filling methods are used to draw the first doping region 101 and the second doping region 102 respectively, and the passivation layer is not shown; Third, to clearly show the morphology of the contact portion 1452, Figure 2 and Figure 3 the main gate 145 is drawn in a white perspective drawing method; Fourth, Figures 1 to 3 the first fine gate 106 is shown by a relatively thick solid line, and the second fine gate 107 is shown by a relatively thin solid line.

[0041] It should be noted that, on the one hand, when the back-contact battery generates carriers based on the photovoltaic effect, the first fine gate 106 is used to collect the carriers generated in the first doping region 101, and the first main gate 104 in contact connection with the first fine gate 106 is used to further collect the carriers collected in the first fine gate 106. On this basis, the first main gate 104 and the first fine gate 106 are in contact connection and their positive projections on the substrate 100 are both located in the positive projection of the first doping region 101 on the substrate 100. In other words, along the third direction Z (the thickness direction of the substrate 100), not only is the first fine gate 106 directly opposite to the first doping region 101, but also the first main gate 104 is directly opposite to the first doping region 101. There is also a first doping region 101 in the interval between two adjacent same-sex fine gates 167, such as two adjacent first fine gates 106.

[0042] Thus, at least a partial number of the first main grids 104 are designed to include a non-contact portion 1451 and a contact portion 1452. The contact portion 1452 penetrates through the passivation layer 103 and is in contact connection with the first doped region 101. A single contact portion 1452 is at least located in the interval between two adjacent first fine grids 106. Then, the contact portion 1452 of the first main grid 104 will be in contact connection with the first doped region 101 located in the interval between two adjacent first fine grids 106, so that the carriers in the first doped region 101 located in the interval between two adjacent first fine grids 106 can be directly transmitted to the non-contact portion 1451 via the contact portion 1452. In other words, the carriers in the first doped region 101 located in the interval between two adjacent first fine grids 106 can be directly collected by the first main grid 104 along the third direction Z, without first passing through the first fine grid 106 and then being collected by the first main grid 104, which is beneficial to shortening the transmission distance of the carriers in the first doped region 101 to the first main grid 104, thereby reducing the transmission loss of the carriers, and thus being beneficial to improving the carrier collection efficiency of the first main grid 104 to improve the photoelectric conversion efficiency of the back contact battery. In addition, in the first main grid 104 including the contact portion 1452, the non-contact portion 1451 does not penetrate through the passivation layer 103 and is only located on the side of the passivation layer 103 away from the substrate 100. Then, the non-contact portion 1451 is not in contact connection with the first doped region 101, so that only a partial area of the first main grid 104 is in contact connection with the first doped region 101, so as to avoid the carrier recombination caused by the large-area contact between the first main grid 104 and the first doped region 101 while improving the carrier collection efficiency of the first main grid 104, and to control the relatively small recombination loss of the carriers.

[0043] On the other hand, when the back contact battery generates carriers based on the photovoltaic effect, the second fine grid 107 is used to collect the carriers generated in the second doped region 102, and the second main grid 105 in contact connection with the second fine grid 107 is used to further collect the carriers collected in the second fine grid 107. On this basis, the second main grid 105 and the second fine grid 107 are in contact connection and their orthographic projections on the substrate 100 are both located in the orthographic projection of the second doped region 102 on the substrate 100. In other words, along the third direction Z, not only is the second fine grid 107 opposite to the second doped region 102, but the second main grid 105 is also opposite to the second doped region 102. The third direction Z is the thickness direction of the substrate 100, so there is also a second doped region 102 in the interval between two adjacent same-sex fine grids 167, such as two adjacent second fine grids 107.

[0044] Thus, at least a partial number of the second main grids 105 are designed to include a non-contact portion 1451 and a contact portion 1452. The contact portion 1452 penetrates through the passivation layer 103 and is in contact connection with the second doped region 102. A single contact portion 1452 is at least located in the interval between two adjacent second fine grids 107. Then, the contact portion 1452 of the second main grid 105 will be in contact connection with the second doped region 102 located in the interval between two adjacent second fine grids 107, so that the carriers in the second doped region 102 located in the interval between two adjacent second fine grids 107 can be directly transmitted to the non-contact portion 1451 via the contact portion 1452. In other words, the carriers in the second doped region 102 located in the interval between two adjacent second fine grids 107 can be directly collected by the second main grid 105 along the third direction Z, without first passing through the second fine grid 107 and then being collected by the second main grid 105, which is beneficial to shortening the transmission distance of the carriers in the second doped region 102 to the second main grid 105, thereby reducing the transmission loss of the carriers, and thus being beneficial to improving the carrier collection efficiency of the second main grid 105 to improve the photoelectric conversion efficiency of the back contact battery. In addition, in the second main grid 105 including the contact portion 1452, the non-contact portion 1451 does not penetrate through the passivation layer 103 and is only located on the side of the passivation layer 103 away from the substrate 100. Then, the non-contact portion 1451 is not in contact connection with the second doped region 102. Only a partial area of the second main grid 105 is in contact connection with the second doped region 102, so as to avoid the carrier recombination caused by the large-area contact between the second main grid 105 and the second doped region 102 while improving the carrier collection efficiency of the second main grid 105, and to control the relatively small recombination loss of the carriers.

[0045] In some cases, compared with the solution where the entire main grid is located on the side of the passivation layer away from the substrate, that is, the entire main grid is not in contact connection with the doped region, in the back contact battery designed in an embodiment of the present disclosure, at least a partial number of the main grids 145 are designed to include a contact portion 1452 in contact connection with the doped region 112 and a non-contact portion 1451 not in contact connection with the doped region 112, which is beneficial to shortening the transmission path of the carriers from the doped region 112 to the main grid 145 via the contact portion 1452 to reduce the transmission loss, and based on the design of the non-contact portion 1451, avoiding the carrier recombination caused by the large-area contact between the main grid 145 and the doped region 112, thereby at least being beneficial to improving the photoelectric conversion efficiency of the back contact battery by about 0.05% or more.

[0046] The back contact battery provided by an embodiment of the present disclosure will be described in more detail below with reference to the drawings.

[0047] In some embodiments, with combined reference Figures 4 to 6, the first fine grid 106 penetrates through the passivation layer 103 and is in contact connection with the first doped region 101; the second fine grid 107 penetrates through the passivation layer 103 and is in contact connection with the second doped region 102. It should be noted that most of the surface area of the substrate 100 is composed of the first doped region 101 and the second doped region 102. The orthographic projection area of the first doped region 101 on the substrate 100 is greater than the sum of the orthographic projection areas of the first main grid 104 and the first fine grid 106 on the substrate 100, and the orthographic projection area of the second doped region 102 on the substrate 100 is greater than the sum of the orthographic projection areas of the second main grid 105 and the second fine grid 107 on the substrate 100.

[0048] Among them, Figure 5 is Figure 2 a partial cross-sectional schematic diagram of the back-contact battery shown along the second cross-sectional direction BB1; Figure 6 is Figure 2 a partial cross-sectional schematic diagram of the back-contact battery shown along the third cross-sectional direction CC1.

[0049] The main grid 145 including the non-contact portion 1451 and at least one contact portion 1452 will be described in detail below. It should be emphasized that the main grid 145 mentioned later can be either the first main grid 104 or the second main grid 105.

[0050] In some embodiments, with reference to Figure 2 and Figure 5 , or with reference to Figure 2 and Figure 7 , Figure 7 is another partial enlarged top view schematic diagram of the back-contact battery provided by an embodiment of the present disclosure. A single main grid 145 may include a non-contact portion 1451 and a contact portion 1452. Among them, the non-contact portion 1451 extends along the second direction Y, and in the third direction Z, a single non-contact portion 1451 is directly opposite to a plurality of same-sex fine grids 167.

[0051] As for the positional relationship between a single non-contact portion 1451 and the same-sex fine grid 167, it includes at least the following two examples: In some examples, with reference to Figure 2 and Figure 5 , or with reference to Figure 2 and Figure 7, a single contact portion 1452 is in contact connection with at least one same-sex fine grid 167 and is at least located in two intervals of at least three adjacent same-sex fine grids 167. In this way, the carriers near the contact connection between the contact portion 1452 and the same-sex fine grid 167 can also be directly transmitted to the non-contact portion 1451 through the contact portion 1452. Even if the subsequent solder strip causes a break in the part of the same-sex fine grid 167 that crosses the main grid 145 during the contact connection, the carriers in the doping region 112 directly opposite to the intersection of the same-sex fine grid 167 and the main grid 145 can be effectively collected through the contact portion 1452 to ensure the high-efficiency collection efficiency of the main grid 145 for carriers.

[0052] In one example, with reference to Figure 2 and Figure 7 , in the same main grid 145, the contact portion 1452 extends along the second direction Y in the same way as the non-contact portion 1451, and in the third direction Z, a single contact portion 1452 is in contact connection with a plurality of same-sex fine grids 167. In this way, a contact portion 1452 is provided at the intersection of the main grid 145 and any same-sex fine grid 167, and a contact portion 1452 is also provided in the interval between any two adjacent same-sex fine grids 167, which is beneficial to further ensuring the high-efficiency collection efficiency of the main grid 145 for carriers and effectively reducing the risk of breakage of the part of the same-sex fine grid 167 that crosses the main grid 145.

[0053] In some other examples, a single contact portion may be only located in the interval between two adjacent same-sex fine grids.

[0054] In the above two examples, in a single main grid 145, a non-contact portion 1451 is only in contact connection with a single contact portion 1452. In the doping region 112 opposite to the interval between the adjacent same-sex fine grids 167, at least part of the region is in contact connection with the contact portion 1452 to directly collect the carriers in the doping region 112 through the contact portion 1452 without passing through the same-sex fine grid 167, thereby shortening the transmission distance of the carriers in at least part of the region of the doping region 112 to the main grid 145, reducing the transmission loss of the carriers, and being beneficial to improving the collection efficiency of the main grid 145 for carriers to improve the photoelectric conversion efficiency of the back-contact battery.

[0055] It should be noted that Figure 2 , Figure 4 , Figure 5 and Figure 7 only take the main grid 145 as the first main grid 104 as an example. In actual applications, when the second main grid includes a contact portion and a non-contact portion, the positional relationship between the contact portion and the non-contact portion and the second fine grid is similar to the positional relationship between the contact portion and the non-contact portion in the first main grid and the first fine grid, which will not be elaborated here.

[0056] In some other embodiments, with reference toFigure 8 or Figure 9 For a single main grid 145, it may include a non-contact part 1451 and a plurality of contact parts 1452 arranged at intervals. Among them, the non-contact part 1451 extends along the second direction Y, and in the third direction Z, a single non-contact part 1451 faces a plurality of same-sex fine grids 167.

[0057] Among them, Figure 8 is another partially enlarged top view schematic diagram of the back contact battery provided by an embodiment of the present disclosure; Figure 9 is another partially sectional schematic diagram of the back contact battery along the second section direction BB1 provided by an embodiment of the present disclosure.

[0058] Regarding the positional relationship between a single non-contact part 1451 and the same-sex fine grid 167, at least the following two examples are included: In some examples, referring to Figure 8 , a single contact part 1452 is in contact connection with at least one same-sex fine grid 167 and is at least located in two intervals of at least three adjacent same-sex fine grids 167. In this way, the carriers near the contact connection between the contact part 1452 and the same-sex fine grid 167 can also be directly transmitted to the non-contact part 1451 by means of the contact part 1452. Even if the subsequent solder strip is in contact connection with the main grid 145 and causes the fracture of the part of the same-sex fine grid 167 that crosses the main grid 145, the carriers in the doping region 112 directly opposite to the intersection of the same-sex fine grid 167 and the main grid 145 can be effectively collected by means of the contact part 1452 to ensure the high-efficiency collection efficiency of the main grid 145 for carriers.

[0059] In one example, continuing to refer to Figure 8 , in the same main grid 145, there is a same-sex fine grid 167 spaced between two adjacent contact parts 1452 along the second direction Y. When a single contact part 1452 is in contact connection with at least one same-sex fine grid 167, in the second direction Y, the carriers in the doping region 112 between two adjacent contact parts 1452 can be selected nearby and transmitted to the non-contact part 1452 by means of the same-sex fine grid 167 or any contact part 1452 to ensure the high-efficiency collection efficiency of the main grid 145 for carriers.

[0060] In some other examples, referring to Figure 9 , a single contact part 1452 is only located in the interval between two adjacent same-sex fine grids 167.

[0061] In one example, continuing to refer to Figure 9, a contact portion 1452 is disposed in the interval between any two adjacent same-sex fine grids 167. In this way, the regions in the doping region 112 that are opposite to the intervals between any two adjacent same-sex fine grids 167 are in contact connection with the contact portion 1452, so that the carriers in the regions of the doping region 112 that are far from the same-sex fine grids 167 can be directly transmitted to the non-contact portion 1451 by means of the contact portion 1452, which is beneficial to shortening the transmission distance of the carriers in multiple regions of the doping region 112 that are opposite to the intervals between two adjacent same-sex fine grids 167, further improving the carrier collection efficiency of the main grid 145, and thus improving the photoelectric conversion efficiency of the back-contact battery.

[0062] In the above two examples, in a single main grid 145, a non-contact portion 1451 is in contact connection with a plurality of contact portions 1452 arranged at intervals, so that the carriers in at least two places in the doping region 112 can be directly transmitted to the non-contact portion 1451 by means of the contact portion 1452, so as to improve the carrier collection efficiency of the main grid 145. In addition, a contact portion 1452 with a large contact area with the doping region 112 in the main grid 145 is avoided, so as to further avoid the carrier recombination caused by the large-area contact between the main grid 145 and the doping region 112, and further reduce the recombination loss of the carriers.

[0063] It should be noted that Figure 8 and Figure 9 only take the first main grid 104 as an example of the main grid 145. In practical applications, when the second main grid includes a contact portion and a non-contact portion, the positional relationship between the contact portion and the non-contact portion and the second fine grid is similar to the positional relationship between the contact portion and the non-contact portion and the first fine grid in the first main grid, and will not be elaborated here.

[0064] In some embodiments, referring to Figure 2 or Figure 10 , Figure 10 is a partial enlarged bottom-up view of the main grid in the back-contact battery provided by an embodiment of the present disclosure. The orthographic projection shape of the contact portion 1452 on the substrate 100 may be serrated; in other embodiments, referring to Figure 3 or Figure 11 , Figure 11 is another partial enlarged bottom-up view of the main grid in the back-contact battery provided by an embodiment of the present disclosure. The orthographic projection shape of the contact portion 1452 on the substrate 100 may be wavy.

[0065] It should be noted that both the serrated and wavy orthographic projection shapes are non-linear and have multiple bends along the second direction Y. The difference between the serrated and wavy shapes lies in whether the bends are zigzag or curved. In other words, the difference between the serrated and wavy shapes lies in whether the transition at the bends is smooth.

[0066] Moreover, the orthographic projection shape of the contact portion 1452 on the substrate 100 is serrated or wavy. Compared with the isotropic fine grid 167 with a similar straight-line orthographic projection shape, on the one hand, the cross-sectional area of the contact portion 1452 itself is larger, which is beneficial to reducing the transmission resistance of the contact portion 1452 itself, improving the carrier transmission efficiency of the contact portion 1452, shortening the carrier transmission distance, and further reducing the carrier transmission loss. On the other hand, the contact area between the contact portion 1452 and the doped region 112 is also larger, and the contact area between the contact portion 1452 and the non-contact portion 1451 is also larger. Therefore, it is beneficial to reduce the contact resistance between the contact portion 1452 and the doped region 112, and reduce the contact resistance between the contact portion 1452 and the non-contact portion 1451, shortening the carrier transmission distance and further reducing the transmission loss during the process of carriers being transmitted from the doped region 112 to the non-contact portion 1451. In this way, with the combined action of multiple aspects, it is beneficial to improve the carrier transmission path at the contact portion 1452, further improve the carrier collection efficiency of the main grid 145, and further improve the photoelectric conversion efficiency of the back-contact battery.

[0067] On the other hand, the orthographic projection shape of the contact portion 1452 on the substrate 100 is designed to be serrated or wavy. Compared with the isotropic fine grid 167 with a similar straight-line orthographic projection shape, the risk of the contact portion 1452 being broken due to force can be reduced based on the larger cross-sectional area of the contact portion 1452, which is beneficial to improving the yield of the back-contact battery.

[0068] In some embodiments, referring to Figure 2 , Figure 3 , Figure 7 , Figure 8 , Figure 10 or Figure 11 , the orthographic projection of the contact portion 1452 on the substrate 100 may be located within the orthographic projection of the non-contact portion 1451 on the substrate 100.

[0069] In some embodiments, referring to Figure 4 , Figure 5 or Figure 9 , in the same main grid 145, along the third direction Z, the contact portion 1452 and the non-contact portion 1451 are stacked.

[0070] In some embodiments, in combination with referring to Figure 2 and Figure 10 , or Figure 3 and Figure 11, along the first direction X, the width of the non-contact portion 1451 is the first width W1, and the width of the layout area occupied by the contact portion 1452 is the second width W2. The ratio of the second width W2 to the first width W1 can be 0.2 to 0.5. For example, it can be 0.25, 0.3, 0.35, 0.4, or 0.45, etc.

[0071] It should be noted that to control the main grid 145 from occupying too much width in the first direction X, so as to avoid the opening width at the disconnection of the first fine grid 106 or the second fine grid 107 from being too large, and to avoid the low layout length of the first fine grid 106 or the second fine grid 107 in the first direction X, the first width W1 of the non-contact portion 1451 in the main grid 145 will be controlled within a preset range. On this basis, if the ratio of the second width W2 to the first width W1 is less than 0.2, the second width W2 of the layout area occupied by the contact portion 1452 is too small, which will reduce the bending degree of the contact portion 1452 and is not conducive to increasing the contact area between the contact portion 1452 and the doped region 112 per unit length in the second direction Y, so it is not conducive to improving the ability of the contact portion 1452 to collect carriers in the doped region 112; if the ratio of the second width W2 to the first width W1 is greater than 0.5, the second width W2 of the contact portion 1452 is too large, resulting in too large a contact area between the contact portion 1452 and the doped region 112, which is likely to cause a large amount of carrier recombination and is not conducive to reducing the recombination loss of carriers. Thus, designing the ratio of the second width W2 to the first width W1 to be 0.2 to 0.5 is beneficial to ensuring a high collection efficiency of the contact portion 1452 for carriers in the doped region 112 while avoiding carrier recombination caused by large-area contact between the main grid 145 and the doped region 112, so as to ensure a small recombination loss of carriers.

[0072] In addition, by designing the first width W1 of the non-contact portion 1451 to be greater than the second width W2 of the layout area occupied by the contact portion 1452, the non-contact portion 1451 in the main grid 145 can be used to further increase the overall cross-sectional area of the main grid 145, so as to reduce the overall transmission resistance of the main grid 145 and thus improve the conductivity of the main grid 145.

[0073] It should be noted that the width of the layout area occupied by the contact portion 1452 being the second width W2 means: among the contact portion 1452 including a plurality of sequentially connected bending segments, the distance between the two bending points that are farthest apart in the first direction X in the bending segments. In some cases, the second width W2 can be the width at the widest part of the contact portion 1452 in the first direction X.

[0074] In some embodiments, in combination with reference to Figure 2 and Figure 10 , or Figure 3 and Figure 11, along the first direction X, the width of the layout area occupied by the contact portion 1452 is the second width W2, the width of the contact portion 1452 is the third width W3, and the ratio of the third width W3 to the second width W2 can be 0.2 to 0.8. For example, it can be 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, or 0.75, etc.

[0075] If the ratio of the third width W3 to the second width W2 is less than 0.2, the third width W3 of the contact portion 1452 is too small, which is not conducive to reducing the transmission resistance of the contact portion 1452 itself, is not conducive to improving the ability of the contact portion 1452 to collect carriers in the doped region 112, and is not conducive to reducing the contact resistance between the contact portion 1452 and the doped region 112; if the ratio of the third width W3 to the second width W2 is greater than 0.8, the third width W3 of the contact portion 1452 is too large, resulting in too large a contact area between the contact portion 1452 and the doped region 112, which is likely to cause a large amount of carrier recombination and is not conducive to reducing the recombination loss of carriers. Thus, designing the ratio of the third width W3 to the second width W2 to be 0.2 to 0.8 is conducive to ensuring a high collection efficiency of the contact portion 1452 for carriers in the doped region 112 while avoiding carrier recombination caused by large-area contact between the main gate 145 and the doped region 112, so as to ensure a small recombination loss of carriers.

[0076] It should be noted that the third width W3 of the contact portion 1452 refers to: in the contact portion 1452 including a plurality of sequentially connected bent segments, the width of the bent segment in the first direction X. In some cases, the third width W3 can be the width at the narrowest part of the contact portion 1452 in the first direction X.

[0077] The structure of a single contact portion 1452 itself will be described in detail below.

[0078] In some embodiments, with reference to Figures 12 to 14, a single contact portion 1452 may include a plurality of sub-contact portions 1452a arranged at intervals in the second direction Y, and any one of the sub-contact portions 1452a penetrates the passivation layer 103 and is in contact connection with the doped region 112. In this way, the area where a single sub-contact portion 1452a is in contact connection with the doped region 112 is regarded as a single converging region. If it is designed that there are a plurality of converging regions between the single contact portion 1452 and the doped region 112, then the carriers in each region of the doped region 112 can preferentially select the sub-contact portion 1452a with the smallest transfer resistance to transfer to the non-contact portion 1451, which is beneficial to ensuring the efficient collection of carriers by the main grid 145. Moreover, dispersing the single contact portion 1452 into a plurality of sub-contact portions 1452a is beneficial to dispersing the area where the single contact portion 1452 is in contact connection with the doped region 112 into a plurality of converging regions, effectively reducing the orthographic projection area of a single converging region on the substrate 100, so as to effectively reduce the recombination loss of carriers at a single converging region, thereby being beneficial to further reducing the recombination loss of carriers between the entire contact portion 1452 and the doped region 112.

[0079] Among them, Figure 12 is a partial bottom-up view schematic diagram of a main grid in a back-contact battery provided by an embodiment of the present disclosure; Figure 13 is another partial bottom-up view schematic diagram of a main grid in a back-contact battery provided by an embodiment of the present disclosure; Figure 14 is still another partial cross-sectional view schematic diagram of a back-contact battery along the second cross-section direction BB1 provided by an embodiment of the present disclosure.

[0080] In some examples, referring to Figure 12 or Figure 13 , the orthographic projection shape of the single contact portion 1452 on the substrate 100 can be regarded as including a plurality of bent segments arranged at intervals in the second direction Y, and a single bent segment can be regarded as a single sub-contact portion 1452a. In other examples, the orthographic projection shape of the single contact portion on the substrate can be regarded as a straight line disconnected into multiple segments, and the sub-contact portion can be regarded as a certain line segment in the straight line.

[0081] In other embodiments, referring to Figure 15 , Figure 15Another partial upward view schematic diagram of the main grid in the back-contact battery provided by an embodiment of the present disclosure. A single contact portion 1452 may include a plurality of contact points 1452b arranged at intervals along the first direction X and / or the second direction Y. Any contact point 1452b penetrates the passivation layer 103 and is in contact connection with the doped region 112. In this way, regarding the area where a single contact point 1452b is in contact connection with the doped region 112 as a single converging point, and designing that there are a plurality of converging points between a single contact portion 1452 and the doped region 112, the carriers in each region of the doped region 112 can preferentially select the contact point 1452b with the smallest transmission resistance to transmit to the non-contact portion 1451, which is beneficial to ensuring the efficient collection of carriers by the main grid 145. Moreover, dispersing a single contact portion 1452 into a plurality of contact points 1452b is beneficial to dispersing the area where the single contact portion 1452 is in contact connection with the doped region 112 into a plurality of converging points, effectively reducing the orthographic projection area of a single converging point on the substrate 100, so as to effectively reduce the recombination loss of carriers at a single converging point, thereby being beneficial to further reducing the recombination loss of carriers between the entire contact portion 1452 and the doped region 112.

[0082] It should be noted that Figure 15 only takes the example that a single contact portion 1452 includes a plurality of contact points 1452b arranged at intervals along the first direction X and at intervals along the second direction Y. In practical applications, the plurality of contact points included in a single contact portion may be arranged only at intervals along the first direction, or the plurality of contact points included in a single contact portion may be arranged only at intervals along the second direction.

[0083] In some embodiments, referring to Figures 1 to 5 、 Figures 7 to 15 the orthographic projection area of the non-contact portion 1451 on the substrate 100 is the first area, and the orthographic projection area of the contact portion 1452 on the substrate 100 is the second area. The ratio of the second area to the first area may be 0.2 to 0.5. For example, it may be 0.25, 0.3, 0.35, 0.4, or 0.45, etc.

[0084] It is worth noting that the positive projection area of ​​the contact portion 1452 on the substrate 100, that is, the second area, can be regarded as the contact area between the contact portion 1452 and the doped region 112. If the ratio of the second area to the first area is less than 0.2, the contact area between the contact portion 1452 and the doped region 112 is too small, which is not conducive to reducing the contact resistance between the contact portion 1452 and the doped region 112, and is not conducive to improving the collection ability of the contact portion 1452 for carriers in the doped region 112; if the ratio of the second area to the first area is greater than 0.5, the contact area between the contact portion 1452 and the doped region 112 is too large, which is easy to cause a large carrier recombination, which is not conducive to reducing the carrier recombination loss. In this way, the design of the ratio of the second area to the first area is 0.2~0.5, which is conducive to ensuring that the contact portion 1452 has a high collection efficiency of carriers in the doped region 112, while avoiding the carrier recombination caused by the large-area contact between the main gate 145 and the doped region 112, so as to ensure a small carrier recombination loss.

[0085] In some embodiments, reference Figure 4 , Figure 9 or Figure 14 Taking the surface of the substrate 100 as a reference plane, the top surface of the contact portion 1452 protrudes above the top surface of the passivation layer 103 .

[0086] In some cases, along the third direction Z, the thickness of the passivation layer 103 is at the nanometer level, and the thickness of the contact portion 1452 is at the micrometer level. Thus, the thickness of the contact portion 1452 is greater than that of the passivation layer 103 .

[0087] In some cases, along the third direction Z, the contact portion 1452 may be divided into two parts stacked up and down, one part penetrates the passivation layer 103 , and the other part is embedded in the non-contact portion 1451 .

[0088] In some embodiments, reference Figure 6 , Figure 9 or Figure 14 , taking the surface of the substrate 100 as a reference plane, the top surface of the homogeneous fine gate 167 can be flush with the top surface of the passivation layer 103. In practical applications, the top surface of the homogeneous fine gate can also protrude from the top surface of the passivation layer.

[0089] In summary, when carriers are generated in the back-contact battery based on the photovoltaic effect, the first fine grid 106 is used to collect the carriers generated in the first doped region 101, and the first main grid 104 in contact connection with the first fine grid 106 is used to further collect the carriers collected in the first fine grid 106; the second fine grid 107 is used to collect the carriers generated in the second doped region 102, and the second main grid 105 in contact connection with the second fine grid 107 is used to further collect the carriers collected in the second fine grid 107. On this basis, there is still the first doped region 101 in the interval between two adjacent same-sex fine grids 167, for example, between two adjacent first fine grids 106, and there is still the second doped region 102 in the interval between two adjacent second fine grids 107. Thus, at least part of the main grids 145 are designed to include a contact portion 1452 in contact connection with the doped region 112 and a non-contact portion 1451 not in contact connection with the doped region 112. Then, the contact portion 1452 of at least part of the first main grids 104 will be in contact connection with the first doped region 101 located in the interval between two adjacent first fine grids 106, and / or the contact portion 1452 of at least part of the second main grids 105 will be in contact connection with the second doped region 102 located in the interval between two adjacent second fine grids 107, so that the carriers in the doped region 112 located in the interval between two adjacent same-sex fine grids 167 can be directly collected by the main grid 145 along the third direction Z, which is beneficial to shortening the transmission distance of the carriers in the doped region 112 to the main grid 145, thereby reducing the transmission loss of the carriers, and thus being beneficial to improving the collection efficiency of the first main grid 104 and / or the second main grid 105 for the carriers, so as to improve the photoelectric conversion efficiency of the back-contact battery.

[0090] In addition, in the main grid 145 including the contact portion 1452, the non-contact portion 1451 does not penetrate through the passivation layer 103 and is only located on the side of the passivation layer 103 away from the substrate 100, so the non-contact portion 1451 is not in contact connection with the doped region 112, and only part of the region of the main grid 145 is in contact connection with the doped region 112, so as to avoid the carrier recombination caused by the large-area contact between the main grid 145 and the doped region 112 while improving the collection efficiency of the main grid 145 for the carriers, so as to control the smaller recombination loss of the carriers.

[0091] According to some embodiments of the present disclosure, on the other hand, the present disclosure embodiments also provide a manufacturing method of a back-contact battery for preparing the back-contact battery provided in the foregoing embodiments. The following will combine the drawings to detail the manufacturing method of the back-contact battery provided in another embodiment of the present disclosure. It should be noted that the same or corresponding parts as those in the foregoing embodiments will not be elaborated here.

[0092] With reference to Figures 1 to 4 and Figure 16 and Figure 17 the manufacturing method of the back-contact battery may include the following steps: Reference Figure 16 , Figure 16 is a partial cross-sectional schematic diagram after forming a first doped region 101, a second doped region 102, and a passivation layer 103 in the manufacturing method of a back-contact battery provided in another embodiment of the present disclosure. A substrate 100 is provided; the first doped region 101 and the second doped region 102 spaced apart from each other are formed on the substrate 100; the passivation layer 103 is formed, and the passivation layer 103 is located on the side of both the first doped region 101 and the second doped region 102 away from the substrate 100.

[0093] With reference to Figure 16 and Figures 1 to 4 , a first main grid 104 and a second main grid 105 arranged alternately along the first direction X and a first fine grid 106 and a second fine grid 107 arranged alternately along the second direction Y are formed; wherein, the first fine grid 106 is disconnected at the second main grid 105, the second fine grid 107 is disconnected at the first main grid 104, the first main grid 104 and the first fine grid 106 are in contact connection and the orthographic projections on the substrate 100 are both located in the orthographic projection of the first doped region 101 on the substrate 100, the second main grid 105 and the second fine grid 107 are in contact connection and the orthographic projections on the substrate 100 are both located in the orthographic projection of the second doped region 102 on the substrate 100; at least a part of the main grids 145 include a non-contact part 1451, and at least one contact part 1452 in contact connection with the non-contact part 1451, the contact part 1452 penetrates through the passivation layer 103 and is in contact connection with the doped region 112, and a single contact part 1452 is at least located in the interval between two adjacent same-sex fine grids 167.

[0094] Wherein, the main grid 145 is the first main grid 104, the doped region 112 is the first doped region 101 and the same-sex fine grid 167 is the first fine grid 106, and / or, the main grid 145 is the second main grid 105, the doped region 112 is the second doped region 102 and the same-sex fine grid 167 is the second fine grid 107.

[0095] It should be noted that the non-contact portion 1451 and the contact portion 1452 in the main grid 145 can be completed in different preparation steps respectively, so as to realize the design that only part of the area in the main grid 145 is in contact connection with the doping area 112. Further, the contact portion 1452 is at least formed in the interval between two adjacent same-sex fine grids 167, so that the carriers in the area of the doping area 112 far from the same-sex fine grid 167 can be directly collected by means of the contact portion 1452 without being collected via the same-sex fine grid 167, which is beneficial to shortening the transmission distance of the carriers in the doping area 112 to the main grid 145, thereby reducing the transmission loss of the carriers, and thus being beneficial to improving the carrier collection efficiency of the main grid 145 to improve the photoelectric conversion efficiency of the back contact battery. In addition, it is avoided that the entire main grid 145 is in contact with the doping area 112 to reduce the probability of carrier recombination at the contact connection between the main grid 145 and the doping area 112.

[0096] The formation steps of the first fine grid 106, the second fine grid 107, the first main grid 104 and the second main grid 105 will be described in detail below.

[0097] In some embodiments, with reference to Figure 16 and Figures 1 to 4 , the steps of forming the first fine grid 106, the second fine grid 107, the first main grid 104 and the second main grid 105 may include: printing a burn-through paste on the area of the passivation layer 103 opposite to the contact portion 1452 of the first fine grid 106 and the first main grid 104, and printing a burn-through paste on the area of the passivation layer 103 opposite to the contact portion 1452 of the second fine grid 107 and the second main grid 105; printing a non-burn-through paste on the side of the contact portion 1452 away from the substrate 100 and on a part of the top surface of the passivation layer 103; performing a sintering process to form the contact portion 1452 of the first fine grid 106 and the first main grid 104 penetrating the passivation layer 103 on the first doping area 101, form the contact portion 1452 of the second fine grid 107 and the second main grid 105 penetrating the passivation layer 103 on the second doping area 102, and form the non-contact portion 1451 on the side of the contact portion 1452 away from the substrate 100 and on a part of the top surface of the passivation layer 103.

[0098] It should be noted that on the side of the passivation layer 103 away from the substrate, a burn-through paste and a non-burn-through paste are respectively printed, and then sintered, so that the burn-through paste penetrates into the passivation layer 103 and penetrates the passivation layer 103 to contact the doping region 112. Among them, the materials of the formed first fine grid 106, the contact part 1452 of the first main grid 104, the second fine grid 107, and the contact part 1452 of the second main grid 105 are all burn-through paste, so that the first fine grid 106, the contact part 1452 of the first main grid 104, the second fine grid 107, and the contact part 1452 of the second main grid 105 can all penetrate the passivation layer 103 and contact and connect with the doping region 112. In this way, in the step of printing the burn-through paste for forming the first fine grid 106 and the second fine grid 107, the printing work of the burn-through paste for forming the contact part 1452 of the first main grid 104 and the contact part 1452 of the second main grid 105 can be completed synchronously, and the preliminary printing work of the contact part 1452 in the main grid 145 can be completed without adding extra processes, which is beneficial to simplifying the preparation process of the back-contact battery and improving the preparation efficiency of the back-contact battery.

[0099] In some other embodiments, with reference to Figure 17 and Figure 1 , Figure 17 is a partial cross-sectional schematic diagram after forming the opening 113 in the passivation layer 103 in the manufacturing method of the back-contact battery provided by another embodiment of the present disclosure. After forming the first fine grid 106 and the second fine grid 107, the steps of forming the first main grid 104 and the second main grid 105 may include: referring to Figure 17 , an opening 113 is formed in the region of the passivation layer 103 opposite to the contact part 1452, and the opening 113 penetrates the passivation layer 103; with reference to Figure 17 and Figure 9 , a main grid paste is printed in the opening 113 and on the side of the passivation layer 103 away from the substrate 100; sintering treatment is performed to form a main grid 145 in the opening 113 and on the side of the passivation layer 103 away from the substrate 100, and the contact part 1452 is at least located in the opening 113.

[0100] It should be noted that opening the opening 113 in the passivation layer 103 in advance to expose a part of the region of the doping region 112 is beneficial to ensuring that the subsequently formed contact part 1452 can be filled in the opening 113 to achieve contact connection with the doping region 112. Among them, the doping region 112 exposed by the opening 113 at least includes the doping region 112 located in the interval between two adjacent same-sex fine grids 167 to ensure that the contact part 1452 can collect the carriers in the doping region 112 located in the interval between two adjacent same-sex fine grids 167.

[0101] In some cases, the main grid paste can be a non-burning-through type paste. An opening 113 is formed in the passivation layer 103 in advance, so that the contact portion 1452 of the main grid 145 located in the opening 113 can be in ohmic contact with the doped region 112 directly, and the main grid 145 formed by the non-burning-through type paste will not cause sintering damage to the surface of the doped region 112, so as to further reduce the contact resistance between the contact portion 1452 and the doped region 112. In addition, compared with the commonly used high-burning-through type conductive materials in the market, the low-burning-through type conductive materials have lower costs, which is beneficial to reducing the manufacturing cost of the back-contact battery.

[0102] Moreover, based on the characteristic that the non-burning-through type paste has almost no erosion and burning-through performance, on the basis of meeting the performance of the passivation layer 103, along the third direction Z, the thickness of the passivation layer 103 can be thinned. In other words, there is no need to rely on the thickness of the passivation layer 103 to prevent the contact portion 1452 from further infiltrating into the doped region 112 after burning through the passivation layer 103. Therefore, it is beneficial to reduce the manufacturing cost of the passivation layer 103 based on the thinning of the passivation layer 103, so as to further reduce the manufacturing cost of the back-contact battery. It is also beneficial to reduce the parasitic absorption of light by the passivation layer 103 based on the thinning of the passivation layer 103, so that more light energy can be absorbed by the substrate 100, thereby further improving the photoelectric conversion efficiency of the back-contact battery.

[0103] In some cases, a laser film opening process can be adopted to form an opening 113 in the region of the passivation layer 103 opposite to the contact portion 1452.

[0104] In some embodiments, with reference to Figure 17 , and Figure 2 , Figure 3 , Figure 7 , Figure 8 , Figures 10 to 15 In any one of them, the orthographic projection of the opening 113 on the substrate 100 can coincide with the orthographic projection of the finally formed contact portion 1452 on the substrate 100, and the shape of the orthographic projection of the opening 113 on the substrate 100 is the same as the shape of the orthographic projection of the finally formed contact portion 1452 on the substrate 100.

[0105] In some embodiments, with reference to Figure 1 , the back-contact battery may further include: a plurality of pads (not shown in the figure), located on the side of the main grid 145 away from the substrate 100. It should be emphasized that whether it is the first main grid 104 or the second main grid 105, a plurality of pads arranged at intervals along the second direction Y are provided on a single main grid 145.

[0106] According to some embodiments of the present disclosure, on the other hand, an embodiment of the present disclosure further provides a photovoltaic module, which is formed by connecting a plurality of back-contact batteries provided by the foregoing embodiments, or by connecting back-contact batteries formed by the manufacturing methods of back-contact batteries provided by the foregoing embodiments. The following will describe the photovoltaic module provided by another embodiment of the present disclosure with reference to the accompanying drawings. It should be noted that the same or corresponding parts as the foregoing embodiments will not be described in detail herein.

[0107] With reference to Figure 18 、 Figure 19 and Figures 1 to 15 , the photovoltaic module includes: a battery string, which is formed by connecting a plurality of back-contact batteries 40 provided by the foregoing embodiments, or by connecting back-contact batteries formed by the manufacturing methods of back-contact batteries provided by the foregoing embodiments; an encapsulant film 41 for covering the surface of the battery string; and a cover plate 42 for covering the surface of the encapsulant film 41 facing away from the battery string.

[0108] Wherein, Figure 18 A partial three-dimensional schematic diagram of a photovoltaic module provided by another embodiment of the present disclosure, Figure 19 is Figure 18 A partial cross-sectional schematic diagram of the photovoltaic module shown in the direction of the fourth section DD1.

[0109] In some embodiments, the back-contact batteries 40 are electrically connected in the form of a whole piece or multiple sub-pieces to form a plurality of battery strings, and the plurality of battery strings are electrically connected in series and / or in parallel. The back-contact battery 40 can be a whole battery or a sliced battery, and the sliced battery refers to a battery formed by cutting a complete whole battery through a cutting process.

[0110] In some embodiments, with reference to Figure 18 and Figure 19 , the plurality of back-contact batteries 40 can be electrically connected through a conductive strip 43. Figure 18 and Figure 19 Only show a positional relationship between the back-contact batteries 40. In actual applications, the grid lines of adjacent back-contact batteries can also be located on different sides respectively, and the conductive strip connects different sides of two adjacent back-contact batteries.

[0111] In some embodiments, the encapsulation film 41 includes a first encapsulation layer and a second encapsulation layer. The first encapsulation layer covers one of the front or back surfaces of the back-contact battery 40, and the second encapsulation layer covers the other of the front or back surfaces of the back-contact battery 40. Specifically, at least one of the first encapsulation layer or the second encapsulation layer can be an organic encapsulation film such as a polyvinyl butyral (PVB) film, an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene co-elastic body (POE) film, or a polyethylene terephthalate (PET) film. Alternatively, at least one of the first encapsulation layer or the second encapsulation layer can also be a film such as an EP film, an EPE film, or a PVP film. Among them, the EP film refers to a co-extruded film composed of an EVA film and a POE film stacked, the EPE film refers to a co-extruded film formed by sequentially stacking an EVA film + a POE film + an EVA film, and the PVP film refers to a co-extruded film formed by stacking a POE film + an EVA film + a POE film. The co-extruded film can be prepared by extruding one or more raw materials onto another film that has already been made during the film processing, or by bonding different types of films that have already been made together.

[0112] In some cases, there is a demarcation line between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination process, there will no longer be the concept of the first encapsulation layer and the second encapsulation layer in the formed photovoltaic module, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0113] In some embodiments, the cover plate 42 can be a cover plate with a light-transmitting function such as a glass cover plate or a plastic cover plate. Specifically, the surface of the cover plate 42 facing the encapsulation film 41 can be a concave-convex surface or a suede surface including a plurality of convex structures, so as to increase the utilization rate of incident light. The cover plate 42 includes a first cover plate and a second cover plate. The first cover plate is opposite to the first encapsulation layer, and the second cover plate is opposite to the second encapsulation layer.

[0114] In some cases, when the back-contact battery 40 is a battery with main grids, the surface of the back-contact battery 40 has a plurality of main grids arranged at intervals in a first direction and a plurality of fine grids arranged at intervals in a second direction. During the process of constructing a battery string using the back-contact battery 40, the conductive tape 43 is electrically connected to at least one main grid on each of two adjacent back-contact batteries 40.

[0115] Those of ordinary skill in the art will understand that the above embodiments are specific examples for implementing the present disclosure. In actual applications, various changes can be made to them in form and details without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be subject to the scope defined by the claims.

Claims

1. A back contact battery, characterized in that: include: substrate; A first doping region and a second doping region located on the substrate and spaced apart from each other; A passivation layer, located on a side of the first doping region and the second doping region away from the substrate; A first main gate and a second main gate are alternately arranged along a first direction, and a first fine gate and a second fine gate are alternately arranged along a second direction, the first fine gate is disconnected at the second main gate, the second fine gate is disconnected at the first main gate, the first main gate and the first fine gate are in contact with each other, and their orthographic projections on the substrate are both located in the orthographic projection of the first doped region on the substrate, and the second main gate and the second fine gate are in contact with each other, and their orthographic projections on the substrate are both located in the orthographic projection of the second doped region on the substrate; At least part of the main gates include a non-contact portion and at least one contact portion connected to the non-contact portion and the contact portion, the contact portion penetrates the passivation layer and is in contact with the doped region, and a single contact portion is at least located in the interval between two adjacent fine gates of the same sex; Among them, the main gate is the first main gate, the doped region is the first doped region and the isotropic fine gate is the first fine gate, and / or the main gate is the second main gate, the doped region is the second doped region and the isotropic fine gate is the second fine gate.

2. The back contact cell according to claim 1, characterized in that: A single main grid includes one non-contact portion and one contact portion, or a single main grid includes one non-contact portion and a plurality of contact portions arranged at intervals; Wherein, a single contact portion is in contact with and connected to at least one of the fine grids of the same sex, and is located at least in two intervals between three adjacent fine grids of the same sex, or a single contact portion is only located in the interval between two adjacent fine grids of the same sex.

3. The back contact cell according to claim 1 or 2, characterized in that: The orthographic projection shape of the contact portion on the substrate includes a sawtooth shape or a wave shape.

4. The back contact cell according to claim 3, characterized in that: Along the first direction, the width of the non-contact portion is a first width, the width of the layout area occupied by the contact portion is a second width, and the ratio of the second width to the first width is 0.2-0.

5.

5. The back contact battery according to claim 3, characterized in that: Along the first direction, the width of the layout area occupied by the contact portion is the second width, the width of the contact portion is the third width, and the ratio of the third width to the second width is 0.2-0.

8.

6. The back contact cell according to claim 1 or 2, characterized in that: The single contact portion includes a plurality of sub-contact portions spaced apart along the second direction, and any of the sub-contact portions penetrates the passivation layer and is in contact with the doped region.

7. The back contact cell according to claim 1 or 2, characterized in that: A single contact portion includes a plurality of contact points arranged at intervals along the first direction and / or the second direction, and any of the contact points penetrates the passivation layer and is in contact with the doped region.

8. The back contact cell according to claim 1, characterized in that: The orthographic projection area of ​​the non-contact portion on the substrate is a first area, the orthographic projection area of ​​the contact portion on the substrate is a second area, and a ratio of the second area to the first area is 0.2-0.

5.

9. The back contact cell according to claim 1, characterized in that: Taking the surface of the substrate as a reference plane, the top surface of the contact portion protrudes above the top surface of the passivation layer.

10. A method for manufacturing a back contact battery, characterized in that: include: providing a substrate; forming a first doping region and a second doping region spaced apart from each other on the substrate; forming a passivation layer, wherein the passivation layer is located on a side of the first doping region and the second doping region away from the substrate; Forming first main grids and second main grids alternately arranged along a first direction and first fine grids and second fine grids alternately arranged along a second direction; The first fine gate is disconnected at the second main gate, the second fine gate is disconnected at the first main gate, the first main gate and the first fine gate are in contact and connection, and their orthographic projections on the substrate are both located in the orthographic projection of the first doped region on the substrate, and the second main gate and the second fine gate are in contact and connection, and their orthographic projections on the substrate are both located in the orthographic projection of the second doped region on the substrate; At least part of the main gates include a non-contact portion and at least one contact portion connected to the non-contact portion and the contact portion, the contact portion penetrates the passivation layer and is in contact with the doped region, and a single contact portion is at least located in the interval between two adjacent fine gates of the same sex; Among them, the main gate is the first main gate, the doped region is the first doped region and the isotropic fine gate is the first fine gate, and / or the main gate is the second main gate, the doped region is the second doped region and the isotropic fine gate is the second fine gate.

11. The method for manufacturing a back contact battery according to claim 10, characterized in that: The steps of forming the first fine gate, the second fine gate, the first main gate and the second main gate include: Printing a fire-through paste on a region of the passivation layer directly facing the contact portion of the first fine gate and the first main gate, and printing the fire-through paste on a region of the passivation layer directly facing the contact portion of the second fine gate and the second main gate; Printing a non-fire-through paste on a side of the contact portion away from the substrate and on a portion of the top surface of the passivation layer; A sintering treatment is performed to form the contact portion of the first fine gate and the first main gate penetrating the passivation layer on the first doping region, to form the contact portion of the second fine gate and the second main gate penetrating the passivation layer on the second doping region, and to form the non-contact portion on the side of the contact portion away from the substrate and on a portion of the top surface of the passivation layer.

12. The method for manufacturing a back contact battery according to claim 10, characterized in that: After forming the first fine gate and the second fine gate, the step of forming the first main gate and the second main gate includes: forming an opening in the passivation layer in a region directly opposite to the contact portion, wherein the opening penetrates the passivation layer; Printing a main gate paste in the opening and on a side of the passivation layer away from the substrate; A sintering process is performed to form the main gate on the side of the opening and the passivation layer away from the substrate, and the contact portion is at least located in the opening.

13. A photovoltaic module, characterized in that: include: A battery string formed by connecting a plurality of back-contact batteries as claimed in any one of claims 1 to 9, or by connecting a plurality of back-contact batteries formed by the method for manufacturing a back-contact battery as claimed in any one of claims 10 to 12; A packaging film, used to cover the surface of the battery string; The cover plate is used to cover the surface of the packaging film away from the battery string.

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