A back contact cell and photovoltaic module

Abstract

The application discloses a back contact cell and a photovoltaic module, and relates to the technical field of photovoltaics, which is used for reducing the parasitic absorption of a first doped region and a second doped region, and is beneficial to improving the bifacial rate of the back contact cell. The back contact cell comprises a cell body, a first electrode and a second electrode arranged on the cell body. The first electrode is arranged on the first doped region and is electrically connected with the first doped region. The second electrode is arranged on the second doped region and is electrically connected with the second doped region. The first electrode and the second electrode both comprise a current collecting electrode. In a second direction, a part between two current collecting electrodes with opposite polarities and adjacent to each other is a first interval sub-region. The width of the first doped sub-region is greater than or equal to the width of the second doped sub-region. The width of at least one first interval sub-region in the second direction is greater than the width of at least one first doped sub-region in the second direction; and / or the area of at least one first interval sub-region is greater than the area of at least one first doped sub-region.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic technology, in particular to a back contact cell and a photovoltaic module. BACKGROUND

[0002] The back contact cell refers to a solar cell in which no electrode is arranged on the light-receiving surface of the cell, and the positive and negative electrodes are arranged on the back surface of the cell, so that the shading of the electrodes on the cell can be reduced, the short-circuit current of the cell can be increased, and the energy conversion efficiency of the cell can be improved.

[0003] However, in the existing back contact cell, the first doped region and / or the second doped region arranged on the back surface of the cell have high parasitic absorption, which leads to low light utilization rate on the back surface side, and is not conducive to improving the bifaciality of the back contact cell. SUMMARY

[0004] The purpose of the present application is to provide a back contact cell and a photovoltaic module for reducing the parasitic absorption of the first doped region and the second doped region, improving the light utilization rate on the first surface side, and improving the bifaciality of the back contact cell.

[0005] To achieve the above purpose, in a first aspect, the present application provides a back contact cell, which comprises a cell body, and a first electrode and a second electrode arranged on the cell body. The cell body has opposite first and second surfaces. The first surface comprises first and second doped regions arranged alternately and spaced apart, and a spacing region between the first and second doped regions. The first electrode is arranged on the first doped region and electrically connected to the first doped region. The second electrode is arranged on the second doped region and electrically connected to the second doped region. The first electrode and the second electrode each comprise a current collecting electrode. The current collecting electrode included in the first electrode and the current collecting electrode included in the second electrode extend in a first direction and are arranged alternately and spaced apart in a second direction. The first direction is different from the second direction. In the second direction, the portion of the spacing region between two current collecting electrodes with opposite polarities and adjacent to each other is a first spacing sub-region. The portion of the first doped region below the current collecting electrode included in the first electrode is a first doped sub-region, and the portion of the second doped region below the current collecting electrode included in the second electrode is a second doped sub-region. The width of the first doped sub-region is greater than or equal to the width of the second doped sub-region. At least one first spacing sub-region has a width in the second direction greater than that of at least one first doped sub-region; and / or, the area of at least one first spacing sub-region is greater than that of at least one first doped sub-region.

[0006] In the case of the above technical solution, when the back contact cell is in a working state, the first doped region and the second doped region can effectively shunt and collect carriers, which is conducive to the formation of photocurrent. The spacing region arranged between the first doped region and the second doped region is used to electrically isolate the first doped region and the second doped region with opposite conductivity types, thereby reducing the carrier recombination rate between the two. It can be understood that the spacing region does not have a doped semiconductor layer extending from the first doped region and / or the second doped region for shunting and collecting carriers and having parasitic absorption (or the thickness of the doped semiconductor layer with parasitic absorption on the spacing region is smaller than the thickness of the doped semiconductor layer with parasitic absorption in the first doped region and / or the second doped region). Based on this, the width of the first doped sub-region in the back contact cell provided by the application is greater than or equal to the width of the second doped sub-region. Moreover, the width and / or area of the first spacing sub-region between two adjacent collector electrodes with opposite polarities are greater than the width and / or area of the first doped sub-region, respectively, which is conducive to increasing the area ratio of the spacing region in the first surface and reducing the risk of leakage between adjacent first doped sub-regions and second doped sub-regions. At the same time, because the first doped region, the second doped region and the spacing region are located in the first surface, when the width and / or area of the first spacing sub-region increases, the area ratio of the spacing region in the first surface increases, and the area ratio of the first doped sub-region and the second doped sub-region in the first surface decreases, which can reduce the parasitic absorption of the first doped region and the second doped region. Moreover, when the area ratio of the first doped sub-region and the second doped sub-region in the first surface decreases, the light-shielding area of the collector electrode arranged on the first doped sub-region and the second doped sub-region also decreases, thereby improving the light utilization rate on the first surface of the cell and improving the bifaciality of the back contact cell.

[0007] As a possible implementation scheme, the surface of the spacing region has a textured structure, and the ratio of the total area of all spacing regions included in the first surface to the total area of the first surface is greater than 50%.

[0008] In the case of the above technical solution, when the ratio of the total area of all spacing regions included in the first surface to the total area of the first surface is greater than 50%, the area ratio of the spacing region is large, which can further reduce the parasitic absorption of the first doped region and the second doped region, and reduce the light-shielding area of the collector electrode. Moreover, the textured structure of the surface of the spacing region has a light-trapping effect, which can further improve the light utilization rate on the first surface of the cell and further improve the bifaciality of the back contact cell. Moreover, the surface of the spacing region has a textured structure with unevenness, which is conducive to increasing the specific surface area of the spacing region, increasing the passivation contact area of the spacing region and the surface passivation layer, and improving the open-circuit voltage and short-circuit current of the cell.

[0009] As a possible implementation, a ratio of a width of the at least one first sub-separation region to a sum of widths of the adjacent first doped sub-region and the second doped sub-region is P1; 0.5 < P1 < 3.

[0010] In the case of the above technical solution, the ratio P1 is within the above range, which is beneficial to prevent the width of the first doped sub-region and / or the second doped sub-region from being too large due to the ratio P1 being too small, thereby further reducing the area ratio of the first doped region including the first doped sub-region and the second doped region including the second doped sub-region in the first surface, reducing the parasitic absorption of the two, and the light-shielding area of the collector electrode electrically connected to the two, respectively. In the case of the surface of the separation region having a textured structure, the width of the first sub-separation region is increased, which can also increase the area ratio of the surface of the first surface provided with the textured structure, thereby further improving the light utilization rate of the first surface side of the cell. In addition, it can also prevent the width of the first doped sub-region and / or the second doped sub-region from being too small due to the ratio P1 being too large, which is beneficial to the first doped region and the second doped region having a certain carrier shunting and collecting capacity, and is beneficial to the first surface side having a relatively low carrier recombination rate. At the same time, it can also prevent the width of the collector electrode provided on the first doped sub-region and / or the second doped sub-region from being too small due to the width of the first doped sub-region and / or the second doped sub-region being too small, thereby reducing the risk of the collector electrode breaking and being beneficial to meeting the electrical interconnection requirement of the collector electrode and the auxiliary bus electrode or the interconnection structure, and reducing the interconnection resistance.

[0011] As a possible implementation, along the second direction, a region between the midlines of two adjacent first doped sub-regions is a unit region, or a region between the midlines of two adjacent second doped sub-regions is a unit region. Along the second direction, a ratio between the width of a single first sub-separation region and the width of the unit region is P2, and The application principle of the beneficial effects in this case is the same as that of the beneficial effects of 0.5 < P1 < 3 described above, which will not be described here. In addition, it can also prevent the carrier transport distance of the carriers at the first sub-separation region from being too large due to the width of the first sub-separation region being too large, thereby reducing the probability of loss such as radiation recombination of the carriers in the transport process, and being beneficial to improving the conversion efficiency of the back contact cell.

[0012] As a possible implementation, in the back contact cell, along the second direction, a ratio between the total number of the collector electrodes included in the first electrode and the collector electrodes included in the second electrode and the width of the first sub-separation region along the second direction is P3, and 0.1 ≤ P3 ≤ 15.

[0013] In the above technical solution, the ratio P3 is within the range, which is beneficial to prevent the first interval sub-region from being too large in width due to the too small ratio P3, thereby shortening the lateral transport distance of the carriers and reducing the lateral transport loss. In addition, it can also prevent the first interval sub-region from being too small in width due to the too large ratio P3. The application principle of preventing the first interval sub-region from being too small in width can be referred to the foregoing description, which will not be repeated here. It should be noted that the ratio range of P3 is calculated based on the width of the first interval sub-region along the second direction in micrometers.

[0014] As a possible implementation, the first doped region is an emitter region. The ratio between the cross-sectional area of the first doped sub-region and the cross-sectional area of the second doped sub-region is P4, and 0.04 < P4 < 30; or, the ratio between the aspect ratio of the first doped sub-region and the aspect ratio of the second doped sub-region is P5, and 0.04 < P5 < 30.

[0015] In the above technical solution, when the first doped region is an emitter region, the first doped region can form a PN junction with the semiconductor substrate included in the cell body. It can be understood that the junction area and the electric field strength of the built-in electric field of the PN junction will affect the splitting and collection rate of the photo-generated carriers in the semiconductor substrate. Based on this, when P4 or P5 is greater than 0.04 and less than 30, the cross-sectional area or the aspect ratio of the first doped sub-region included in the emitter region is greater than the cross-sectional area or the aspect ratio of the second doped sub-region included in the field region, which is beneficial to increase the junction area of the above-mentioned PN junction, and is beneficial to the improvement of the splitting and collection rate of the carriers, and further reduces the carrier recombination rate. It should be noted that the ratio range of P5 is calculated based on the unit of height in nanometers and the unit of width in micrometers.

[0016] As a possible implementation, the surface passivation layer is formed on the side of the first surface of the cell body. The collector electrode included in the first electrode is electrically connected to the first doped region through the surface passivation layer, and the collector electrode included in the second electrode is electrically connected to the second doped region through the surface passivation layer. The ratio between the width of the first interval sub-region along the second direction and the thickness of the surface passivation layer is P6, and 1000 < P6 < 5000.

[0017] In the above technical solution, the value of the ratio P6 is within the range, which is beneficial to prevent the first interval sub-region from being too small in width due to the too small value of the ratio P6. The beneficial effect of preventing the first interval sub-region from being too small in width can be referred to the foregoing, and will not be described herein. In addition, the ratio P6 is prevented from being too large, which prevents the first interval sub-region from being too large in width and / or the surface passivation layer from being too small in thickness, and is beneficial to set the width of the first interval sub-region and the thickness of the surface passivation layer within a reasonable range, so as to increase the width of the first interval sub-region relative to the prior art, thereby reducing parasitic absorption and light-shielding area of the current collecting electrode, and at the same time, solve the problem that the area ratio of the first doped region and the second doped region with field passivation is too small due to the large width and / or area of the interval region, thereby reducing the passivation effect on the first side. It is beneficial to make the first side have a lower carrier recombination rate.

[0018] As a possible implementation, the first electrode and the second electrode further include auxiliary bus electrodes. The auxiliary bus electrodes included in the first electrode and the auxiliary bus electrodes included in the second electrode both extend along the second direction and are alternately and spacedly distributed along the first direction. The auxiliary bus electrodes included in the first electrode are electrically connected with at least part of the current collecting electrodes included in the first electrode, and the auxiliary bus electrodes included in the second electrode are electrically connected with at least part of the current collecting electrodes included in the second electrode. The current collecting electrodes are disconnected at the intersections with the auxiliary bus electrodes having opposite polarities. Along the first direction, the part of the interval region between the current collecting electrode and the auxiliary bus electrode adjacent to the current collecting electrode and having an opposite polarity is a second interval sub-region. The part of the first doped region below the auxiliary bus electrode included in the first electrode is a third doped sub-region, and the part of the second doped region below the auxiliary bus electrode included in the second electrode is a fourth doped sub-region. The width of the second interval sub-region along the first direction is smaller than the width of the larger one of the third doped sub-region and the fourth doped sub-region, or the area of the second interval sub-region is smaller than the area of the larger one of the third doped sub-region and the fourth doped sub-region.

[0019] In the above technical solution, the third doped sub-region and the fourth doped sub-region have a larger width along the first direction, which is beneficial to make the first doped region and the second doped region have a higher carrier shunting and collecting capacity, and is beneficial to reduce the carrier recombination rate.

[0020] As a possible implementation, the width of the third doped sub-region is greater than the width of the first doped sub-region. In this case, it is beneficial to reduce the risk of electric leakage between the auxiliary bus electrode above the third doped sub-region and the second doped region, and to reduce the process difficulty of forming the auxiliary bus electrode above the third doped sub-region.

[0021] As a possible implementation, the fourth doped sub-region has a width greater than that of the second doped sub-region. In this case, it is beneficial to reduce the risk of leakage between the auxiliary bus electrode formed above the fourth doped sub-region and the first doped region, and to reduce the process difficulty of forming the auxiliary bus electrode above the fourth doped sub-region.

[0022] As a possible implementation, the first electrode and the second electrode further comprise an interconnection structure electrically connected with the current collecting electrode. The portion of the first doped region below the interconnection structure comprised by the first electrode is a fifth doped sub-region, and the portion of the second doped region below the interconnection structure comprised by the second electrode is a sixth doped sub-region. The width of the interconnection structure in the second direction is greater than the width of the current collecting electrode. The width of the fifth doped sub-region is greater than the width of the first doped sub-region. The width of the sixth doped sub-region is greater than the width of the second doped sub-region. This is beneficial to reduce the risk of leakage between the interconnection structure and the differently doped region, and to improve the electrical reliability of the back contact cell.

[0023] As a possible implementation, the first electrode and the second electrode further comprise an interconnection structure electrically connected with the current collecting electrode. The portion of the first doped region below the interconnection structure comprised by the first electrode is a fifth doped sub-region, and the portion of the second doped region below the interconnection structure comprised by the second electrode is a sixth doped sub-region. In this case, the ratio between the width of the first interval sub-region in the second direction and the width of the one of the fifth doped sub-region and the sixth doped sub-region having a greater width in the second direction is greater than or equal to one-fiftieth and less than or equal to one-half; and / or, the ratio between the area of the first interval sub-region and the area of the one of the fifth doped sub-region and the sixth doped sub-region having a greater area is greater than or equal to one-fiftieth and less than or equal to one-half. The application principle of the beneficial effects in this case is similar to that of the beneficial effects described above in the case where the width of the third doped sub-region is greater than the width of the first doped sub-region, and will not be described here again.

[0024] In a second aspect, the present application provides a photovoltaic module comprising the back contact cell provided by the first aspect and various implementation manners thereof.

[0025] The beneficial effects of the second aspect and various implementation manners thereof in the present application can be analyzed with reference to the beneficial effects of the first aspect and various implementation manners thereof, and will not be described here again. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings, which are included to provide a further understanding of the present application and constitute a part of this application, illustrate certain illustrative embodiments of the present application and assist in explaining the present application. In the drawings:

[0027] Figure 1 A longitudinal sectional view schematically showing a first structure of the back contact cell provided by an embodiment of the present application.

[0028] Figure 2 Structure distribution of the back side of the back contact cell provided by the embodiment of the present application Figure 1 ;

[0029] Figure 3 Longitudinal sectional view of the second structure of the back contact cell provided by the embodiment of the present application

[0030] Figure 4 Longitudinal sectional view of the third structure of the back contact cell provided by the embodiment of the present application

[0031] Figure 5 Structure distribution of the back side of the back contact cell provided by the embodiment of the present application Figure 2 ;

[0032] Figure 6 Structure distribution of the back side of the back contact cell provided by the embodiment of the present application Figure 3 ;

[0033] Figure 7 Longitudinal sectional view of the fourth structure of the back contact cell provided by the embodiment of the present application

[0034] Figure 8 Structure distribution of the back side of the back contact cell provided by the embodiment of the present application Figure 4 .

[0035] The reference numerals: 11 is the first doped region, 12 is the second doped region, 13 is the interval region, 14 is the current collecting electrode, 15 is the first interval sub-region, 16 is the first doped sub-region, 17 is the second doped sub-region, 18 is the unit region, 19 is the surface passivation layer, 20 is the auxiliary bus electrode, 21 is the second interval sub-region, 22 is the third doped sub-region, 23 is the fourth doped sub-region, 24 is the interconnection structure, 25 is the fifth doped sub-region, 26 is the sixth doped sub-region, 27 is the semiconductor substrate, 28 is the first interface passivation layer, and 29 is the second interface passivation layer. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. It should be understood, however, that the description is merely exemplary of the present application, but not intended to limit the scope of the present application. Also, in the following description, description of well-known structures and techniques is omitted to avoid obscuring the concept of the present application.

[0037] Various structural schematic diagrams according to embodiments of the present application are shown in the accompanying drawings. These diagrams are not drawn to scale, in which certain details are shown in a somewhat exaggerated manner for the purpose of making the drawings more illustrative and understandable, and certain details can be omitted. The shapes of various regions, layers, and the relative sizes and positional relationships between them shown in the drawings are merely exemplary, and in actuality can be deviated due to manufacturing tolerances or technical limitations, and regions / layers with different shapes, sizes, and relative positions can be additionally designed according to actual needs by those skilled in the art.

[0038] In the context of the present application, when one layer / element is referred to as being located "on" another layer / element, the layer / element can be directly located on the other layer / element, or there can be an intermediate layer / element therebetween. In addition, if one layer / element is located "on" another layer / element in one orientation, it can be located "under" the other layer / element when the orientation is reversed. In order to make the technical problems to be solved, technical solutions and beneficial effects of the present application more clear and understandable, the present application is further described in detail below in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are merely used to explain the present application, and are not used to limit the present application.

[0039] In addition, the terms "first", "second", etc. are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited. The meaning of "several" is one or more, unless otherwise explicitly specified and limited.

[0040] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0041] A solar cell is a device capable of converting light energy of the sun into electric energy. Specifically, when the solar cell is in working condition, sunlight is shone on the semiconductor p-n junction of the solar cell, forming new hole-electron pairs, under the action of the built-in electric field of the p-n junction, the photo-generated holes flow to the p region, and the photo-generated electrons flow to the n region. After the circuit is connected, an electric current can be generated. Among them, the solar cell with the positive electrode and the negative electrode on the back of the cell is a back contact cell. Compared with the double-sided contact solar cell, the front side of the back contact cell has no metal electrode blocking, so that the light utilization rate of the light side of the back contact cell is higher, and therefore the back contact cell has higher short-circuit current and photoelectric conversion efficiency. It is one of the technical directions to realize high-efficiency crystalline silicon cells at present.

[0042] However, in the existing back contact cell, in order to improve the collection efficiency of carriers, the area ratio of the first doped region and the second doped region disposed on the back of the cell and having opposite conductivity types is high (or the area ratio of one of the first doped region and the second doped region is high), and the manufacturing materials of the first doped region and the second doped region usually include light-absorbing semiconductor materials such as polysilicon, amorphous silicon, nanocrystalline silicon and microcrystalline silicon, resulting in high parasitic absorption of the first doped region and the second doped region. And in order to timely export the carriers collected by the first doped region and the second doped region with a high area ratio, the cross-sectional area and / or the number of the first electrode disposed on the first doped region and the second electrode disposed on the second doped region are also large, and the light-shielding area of the first electrode and the second electrode is large, thereby resulting in low light utilization rate on the back side of the cell, which is not conducive to improving the double-sided rate of the back contact cell.

[0043] To solve the above technical problems, in a first aspect, embodiments of the present application provide a back contact cell. As Figure 1 and Figure 2As shown, the back contact cell comprises a cell body, and a first electrode and a second electrode disposed on the cell body. The cell body has opposite first and second faces. The first face comprises first and second doped regions 11 and 12 alternately and spacedly distributed, and a spacer region 13 between the first and second doped regions 11 and 12. The first electrode is disposed on and electrically connected with the first doped regions 11. The second electrode is disposed on and electrically connected with the second doped regions 12. The first and second electrodes each comprise a current collecting electrode 14. The current collecting electrodes 14 comprised by the first electrode and the current collecting electrodes 14 comprised by the second electrode extend along a first direction and are alternately and spacedly distributed along a second direction. The first direction is different from the second direction. Along the second direction, the spacer region 13 is located between two current collecting electrodes 14 of opposite polarity and adjacent to each other, and the portion is a first spacer sub-region 15. The portion of the first doped regions 11 below the current collecting electrodes 14 comprised by the first electrode is a first doped sub-region 16, and the portion of the second doped regions 12 below the current collecting electrodes 14 comprised by the second electrode is a second doped sub-region 17. The width of the first doped sub-region 16 is greater than or equal to the width of the second doped sub-region 17. Wherein, the width of at least one first spacer sub-region 15 along the second direction is greater than the width of at least one first doped sub-region 16 along the second direction; and / or, the area of at least one first spacer sub-region 15 is greater than the area of at least one first doped sub-region 16.

[0044] It should be noted that "the portion of the first doped region below the current collecting electrode comprised by the first electrode is a first doped sub-region" means that the complete region of the first doped region corresponding to the portion below the current collecting electrode comprised by the first electrode is a first doped sub-region, and the portion of the region along the second direction not covered by the current collecting electrode comprised by the first electrode also belongs to the first doped sub-region (i.e. the portion of the region with a width greater than the width of the current collecting electrode comprised by the first electrode also belongs to the first doped sub-region). In addition, "the portion of the second doped region below the current collecting electrode comprised by the second electrode is a second doped sub-region" means that the complete region of the second doped region corresponding to the portion below the current collecting electrode comprised by the second electrode is a second doped sub-region, and the portion of the region along the second direction not covered by the current collecting electrode comprised by the second electrode also belongs to the second doped sub-region (i.e. the portion of the region with a width greater than the width of the current collecting electrode comprised by the second electrode also belongs to the second doped sub-region).

[0045] In the case of adopting the above technical solution, under the working state of the back contact cell, the first and second doped regions can effectively shunt and collect carriers, which is beneficial to form a photocurrent. The spacer region disposed between the first and second doped regions is used to electrically isolate the first and second doped regions of opposite conductivity types, thereby reducing the carrier recombination rate between the two. It can be understood that, for example, Figure 1 and Figure 2As shown, the interval region 13 is not provided with a doped semiconductor layer extending from the first doped region 11 and / or the second doped region 12 for shunting and collecting carriers and existing parasitic absorption (or the thickness of the doped semiconductor layer with parasitic absorption on the interval region 13 is less than the thickness of the doped semiconductor layer with parasitic absorption in the first doped region 11 and / or the second doped region 12). Based on this, the width of the first doped sub-region 16 is greater than or equal to the width of the second doped sub-region 17 in the back contact cell provided by the embodiment of the present application. And the width and / or area of the first interval sub-region 15 between the two adjacent collector electrodes 14 with opposite polarities are greater than the width and / or area of the first doped sub-region 16, respectively, which is beneficial to increase the area ratio of the interval region 13 in the first surface and reduce the risk of leakage between the adjacent first doped sub-region 16 and the second doped sub-region 17; at the same time, because the first doped region 11, the second doped region 12 and the interval region 13 are located in the first surface, in the case that the width and / or area of the first interval sub-region 15 is increased, the area ratio of the interval region 13 in the first surface is increased, and the area ratio of the first doped sub-region 16 and the second doped sub-region 17 in the first surface is decreased, which can reduce the parasitic absorption of the first doped region 11 and the second doped region 12. And when the area ratio of the first doped sub-region 16 and the second doped sub-region 17 in the first surface is decreased, the light shielding area of the collector electrode 14 arranged on the first doped sub-region 16 and the second doped sub-region 17 is also decreased, thereby the light utilization rate of the first surface side of the cell can be improved, which is beneficial to improve the bifaciality of the back contact cell.

[0046] In actual application process, the specific structure and material of the cell body are not limited in the embodiment of the present application, as long as it can be applied to the back contact cell provided by the embodiment of the present application.

[0047] For example, the cell body can include a semiconductor substrate, a first doped region and a second doped region. The first doped region is arranged on a local area of the semiconductor substrate corresponding to the first surface side. The second doped region is arranged on a local area of the semiconductor substrate corresponding to the second surface side.

[0048] In the first doped region and the second doped region, the material of only one of them can include the semiconductor material with parasitic absorption, or the material of both of them can include the semiconductor material with parasitic absorption. The semiconductor material with parasitic absorption can be single crystal silicon, polycrystalline silicon, amorphous silicon, microcrystalline silicon, nanocrystalline silicon, etc. When the material of only one of the first doped region and the second doped region includes the semiconductor material with parasitic absorption, the semiconductor material without parasitic absorption included by the other one can be determined according to the type of the carrier transported by itself. For example, when the semiconductor material without parasitic absorption is used to collect electrons, the semiconductor material without parasitic absorption can be ZnO, SnO2, TiO2, etc. Or, when the semiconductor material without parasitic absorption is used to collect holes, the semiconductor material without parasitic absorption can be copper aluminum sulfide or copper aluminum oxide, etc.

[0049] Of course, in the first doped region and the second doped region, the material including the semiconductor material with parasitic absorption can also include the semiconductor material without parasitic absorption.

[0050] Secondly, the materials of the first doped region and the second doped region can be the same or different. For example, the materials of the first doped region and the second doped region can both be polycrystalline silicon or amorphous silicon. For another example, the material of one of the first doped region and the second doped region is polycrystalline silicon, and the material of the other one is amorphous silicon.

[0051] In addition, the conductive type of the first doped region and the second doped region is not specifically limited in the embodiment of the present application. For example, the first doped region can be an N-type doped region, and the second doped region is a P-type doped region. Or, the first doped region can be a P-type doped region, and the second doped region is an N-type doped region.

[0052] As shown in FIG. 1, the first doped region 11 can be directly arranged on the semiconductor substrate 27. Or, as shown in FIG. 2, the first doped region 11 can be arranged on the semiconductor substrate 27 through a buffer layer 28. Figure 1 Figure 3 ​As shown, the battery body can further include a first interface passivation layer 28 between the semiconductor substrate 27 and the first doped region 11. The passivation contact structure composed of the first interface passivation layer 28 and the first doped region 11 has excellent interface passivation effect and can realize selective collection of carriers, reduce the carrier recombination rate on the side of the first surface of the semiconductor substrate 27, and further improve the photoelectric conversion efficiency of the back contact battery. The material and thickness of the first interface passivation layer 28 can be set according to the material of the first doped region 11 and actual requirements, and are not specifically limited here. For example, when the material of the first doped region is doped polysilicon, the first interface passivation layer is a tunnel passivation layer. For another example, when the material of the first doped region includes at least one of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon, the first interface passivation layer is an intrinsic amorphous silicon layer, an intrinsic microcrystalline silicon layer, an intrinsic nanocrystalline silicon layer, or a mixed layer of the above three.

[0053] As for the second doped region, as shown in Figure 1 the above-mentioned second doped region 12 can be directly arranged on the semiconductor substrate 27. Alternatively, as shown in Figure 3 the above-mentioned back contact battery can further include a second interface passivation layer 29 between the semiconductor substrate 27 and the second doped region 12. In this case, the passivation contact structure composed of the second interface passivation layer 29 and the second doped region 12 can realize selective collection of carriers and reduce the carrier recombination rate on the side of the first surface of the semiconductor substrate 27. The material and thickness of the second interface passivation layer 29 can refer to the setting principle of the material and thickness of the first interface passivation layer 28, and will not be repeated here.

[0054] From the aspect of surface topography, as shown in Figure 3 the surface of the first doped region 11 and the surface of the second doped region 12 in the first surface of the battery body can be a plane, at this time the surface of the semiconductor substrate 27 corresponding to the first doped region 11 and the second doped region 12 is also relatively flat, which is beneficial to improve the formation quality of the first doped region 11 and the second doped region 12 on the semiconductor substrate 27 and improve the field passivation effect of the first doped region 11 and the second doped region 12. Alternatively, the surface of the first doped region and the surface of the second doped region can also be a rough surface to further improve the bifaciality of the back contact battery; at the same time, it is beneficial to increase the contact area between the first doped region and the first electrode and between the second doped region and the second electrode, and is beneficial to reduce the contact resistance. In this case, the type and size of the rough surface structure of the first doped region and the second doped region are not specifically limited by the embodiment of the application, and can be set according to actual requirements.

[0055] As for the interval region in the first surface, the surface of the interval region can be a plane. Alternatively, as shown in Figure 4As shown, the surface of the spacing region 13 can also have a textured structure. In this case, the textured structure has a light-trapping effect, which can further improve the light utilization on the first side of the cell and further improve the bifaciality of the back contact cell. Moreover, the surface of the spacing region 13 has a textured structure with unevenness, which is conducive to increasing the specific surface area of the spacing region 13, increasing the passivation contact area of the spacing region 13 and the surface passivation layer 19, and improving the open-circuit voltage and short-circuit current of the cell. In this case, the embodiments of the present application do not make specific limitations on the type and size of the textured structure on the surface of the spacing region 13, which can be set according to actual needs.

[0056] For example, the textured structure on the surface of the spacing region can be a pyramid structure. The one-dimensional size (which can refer to the side length or diagonal length of the base of the pyramid structure, or the height or side length of the pyramid structure) of the pyramid structure can be greater than or equal to 0.5 μm and less than or equal to 5 μm. The apex angle of the pyramid structure can be greater than or equal to 30° and less than or equal to 60°.

[0057] As for the shape of the first doped region, the second doped region and the spacing region in the first surface, it can be set according to actual needs, which is not specifically limited here.

[0058] For example, as shown in Figure 2 and 5 At least part of the first doped region 11 and at least part of the second doped region 12 can be alternately and spacedly distributed in a strip shape. At this time, the first doped region 11 and the second doped region 12 both include strip-shaped doped regions. Moreover, the strip-shaped doped regions included in the first doped region 11 and the second doped region 12 both extend along the first direction and are alternately and spacedly distributed along the second direction.

[0059] For example, as shown in Figure 5 and Figure 6 At least part of the first doped region 11 and at least part of the second doped region 12 can be alternately and spacedly distributed in an interdigital shape. At this time, the first doped region 11 and the second doped region 12 both include strip-shaped doped regions and connecting doped regions. The strip-shaped doped regions included in the first doped region 11 and the second doped region 12 both extend along the first direction and are alternately and spacedly distributed along the second direction. The connecting doped regions included in the first doped region 11 and the second doped region 12 both extend along the second direction and are alternately and spacedly distributed along the first direction. The connecting doped regions included in the first doped region 11 are connected to at least part of the strip-shaped doped regions included in the first doped region 11, and the connecting doped regions included in the second doped region 12 are connected to at least part of the strip-shaped doped regions included in the second doped region 12.

[0060] Wherein, the above-mentioned first direction and second direction can be any two directions parallel to the first surface and different from each other. Optionally, the first direction and the second direction are orthogonal.

[0061] As for the area ratio of the first doped region, the second doped region, and the spacer region in the first surface, and the difference between the width of the first spacer region and the width of the first doped region and the second doped region, they can be determined according to the shape of the first doped region and the second doped region in the actual application scenario, the parasitic absorption and carrier collection efficiency of the first doped region and the second doped region, and the bifaciality requirements of the battery. As long as the width of at least one first spacer region along the second direction is greater than the width of at least one first doped region along the second direction; and / or the area of ​​at least one first spacer region is greater than the area of ​​at least one first doped region.

[0062] For example, the ratio of the total area of ​​all spacer regions included in the first surface to the total area of ​​the first surface can be greater than 50%. For instance, the ratio can be 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or 60%, etc. In this case, the larger area ratio of the spacer regions can further reduce the parasitic absorption of the first and second doped regions, as well as reduce the light-shielding area of ​​the current collector electrode.

[0063] For example, the width of at least one first spacer sub-region is P1, which is the sum of the widths of adjacent first and second doped sub-regions; 0.5 < P1 < 3. For example, the ratio P1 can be 0.51, 0.55, 0.6, 0.7, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.4, 2.6, or 2.8, etc. In this case, the ratio P1 is within the above range, which helps to prevent the width of the first and / or second doped sub-regions from being too large due to the ratio P1 being too small, further reducing the area ratio of the first doped region including the first doped sub-region and the second doped region including the second doped sub-region in the first surface, reducing their parasitic absorption, and reducing the light-shielding area of ​​the current collector electrodes electrically connected to them respectively; and when the surface of the spacer region has a textured structure, increasing the width of the first spacer sub-region can also increase the area ratio of the surface with the textured structure in the first surface, further improving the light utilization rate on the first surface of the battery. In addition, it can prevent the width of the first doped sub-region and / or the second doped sub-region from being too small due to an excessively large ratio P1. This is beneficial for the first and second doped regions to have a certain carrier splitting and collection capability, and for the first side to have a relatively low carrier recombination rate. At the same time, it can also prevent the width of the collector electrode set on the first and / or second doped sub-region from being too small due to the small width of the first doped sub-region and / or the second doped sub-region. This reduces the risk of collector electrode breakage and helps to meet the electrical interconnection requirements between the collector electrode and the auxiliary bus electrode or interconnection structure, thereby reducing the interconnection resistance.

[0064] For example, such as Figure 2 ,Figure 5 and Figure 6 As shown, along the second direction, the region between the center lines of two adjacent first doped sub-regions 16 is a unit region 18, or the region between the center lines of two adjacent second doped sub-regions 17 is a unit region 18. Along the second direction, the ratio between the width of a single first spacer sub-region 15 and the width of the unit region 18 is P2, and... For example, the ratio P2 can be 0.26, 0.28, 0.3, 0.4, 0.5, 0.6, or 0.65, etc. The application principle of the beneficial effect in this case is the same as that of the beneficial effect of 0.5 < P1 < 3 mentioned above, and will not be repeated here. In addition, it can also prevent the carriers from having a large transport distance in the first spacer region due to the excessive width of the first spacer region, reduce the probability of carriers losing power such as radiative recombination during transport, and help improve the conversion efficiency of the back contact cell.

[0065] In practical applications, the cross-sectional area and / or aspect ratio of the first doped region and the second doped region can be the same.

[0066] Or, such as Figure 2 , Figure 5 and Figure 6 As shown, when the first doped region 11 is the emitter region, the ratio between the cross-sectional area of ​​the first doped sub-region 16 and the cross-sectional area of ​​the second doped sub-region 17 is P4, 0.04 < P4 < 30; or, the ratio between the aspect ratio of the first doped sub-region 16 and the aspect ratio of the second doped sub-region 17 is P5, 0.04 < P5 < 30. In this case, when the first doped region 11 is the emitter region, the first doped region 11 can form a PN junction with the semiconductor substrate 27 included in the battery body. It is understood that the junction area and electric field strength of the built-in electric field of the PN junction will affect the shunting and collection rate of photogenerated carriers within the semiconductor substrate 27. Based on this, when P4 or P5 is greater than 0.04 and less than 30, the cross-sectional area or aspect ratio of the first doped sub-region 16 included in the emitter region is greater than the cross-sectional area or aspect ratio of the second doped sub-region 17 included in the field region. This is beneficial for increasing the junction area of ​​the PN junction, improving the shunting and collection rates of charge carriers, and further reducing the carrier recombination rate. It should be noted that when the first and second doped regions are doped semiconductor layers (such as doped amorphous silicon layers, doped polycrystalline silicon layers, doped monocrystalline silicon layers, or doped microcrystalline silicon layers, etc.) disposed on the first surface of the semiconductor substrate, the aspect ratio of the first and / or second doped sub-regions refers to the ratio between the thickness and width of the doped semiconductor layer.

[0067] Exemplarily, in the back contact cell, the ratio between the total number of the current collecting electrodes included by the first electrode and the second electrode and the width of the first interval sub-region along the second direction is P3, and 0.1≤P3≤15. For example, the ratio P3 can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.5, 1, 3, 5, 8, 10, 12 or 15, etc. In this case, the ratio P3 is within the above range, which is beneficial to prevent the width of the first interval sub-region from being too large due to the too small ratio P3, thereby shortening the lateral transport distance of the carriers and reducing the lateral transport loss. In addition, it can also prevent the width of the first interval sub-region from being too small due to the too large ratio P3. The application principle of the beneficial effect of preventing the width of the first interval sub-region from being too small can be referred to the foregoing, which will not be described here.

[0068] As for the size information of the first doped sub-region, the second doped sub-region and the first interval sub-region along the second direction and the length along the first direction, as well as the width along the second direction of the current collecting electrodes included by the first electrode and the second electrode and the total number, they can be set according to the size of the cell body in the actual application scenario and the actual demand, which will not be specifically limited here.

[0069] Exemplarily, the width of the first doped sub-region and / or the second doped sub-region along the second direction can be greater than or equal to 50μm and less than or equal to 500μm. For example, the width of the first doped sub-region and / or the second doped sub-region along the second direction can be 50μm, 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm or 500μm, etc. Optionally, the width of the first doped sub-region and / or the second doped sub-region along the second direction can be greater than or equal to 100μm and less than or equal to 300μm.

[0070] Exemplarily, the width of the first interval sub-region along the second direction can be greater than or equal to 80μm and less than or equal to 1000μm. For example, the width of the first interval sub-region along the second direction can be 80μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm or 1000μm, etc. Optionally, the width of the first interval sub-region along the second direction can be greater than or equal to 100μm and less than or equal to 600μm.

[0071] For example, the length of at least one of the first doped sub-region, the second doped sub-region, and the first spacer sub-region in the first direction can be greater than or equal to 0.05 mm and less than or equal to 300 mm. For example, the length of at least one of the first doped sub-region, the second doped sub-region, and the first spacer sub-region in the first direction can be 0.05 mm, 1 mm, 10 mm, 20 mm, 50 mm, 100 mm, 200 mm, or 300 mm, etc. Optionally, the width of at least one of the first doped sub-region, the second doped sub-region, and the first spacer sub-region in the second direction can be greater than or equal to 50 mm and less than or equal to 220 mm.

[0072] For example, the total area of the first doped sub-region and / or the second doped sub-region in the first face can be greater than or equal to 10 cm 2 and less than or equal to 250 cm 2 . For example, the total area of the first doped sub-region and / or the second doped sub-region in the first face can be 10 cm 2 , 20 cm 2 , 50 cm 2 , 80 cm 2 , 100 cm 2 , 120 cm 2 , 150 cm 2 , 180 cm 2 , 200 cm 2 , or 250 cm 2 , etc. Optionally, the total area of the first doped sub-region and / or the second doped sub-region in the first face can be greater than or equal to 40 cm 2 and less than or equal to 150 cm 2 .

[0073] For example, the total area of the spacer region in the first face can be greater than or equal to 20 cm 2 and less than or equal to 300 cm 2 . For example, the total area of the spacer region in the first face can be 20 cm 2 , 50 cm 2 , 80 cm 2 , 100 cm 2 , 120 cm 2 , 150 cm 2 , 180 cm 2 , 200 cm 2 , 250 cm 2 , or 300 cm 2 , etc. Optionally, the total area of the spacer region in the first face can be greater than or equal to 80 cm 2 and less than or equal to 250 cm 2 .

[0074] As a possible implementation, as shown in Figure 7 The first side of the battery body can be formed with a surface passivation layer 19 to passivate surface defects on the first side of the battery body and reduce the carrier recombination rate. In this case, the current collecting electrode 14 included in the first electrode is electrically connected to the first doped region 11 through the surface passivation layer 19, and the current collecting electrode 14 included in the second electrode is electrically connected to the second doped region 12 through the surface passivation layer 19. In addition, it can be understood that when the area ratio of the first doped region 11 and the second doped region 12 having a field passivation effect on the first side is reduced, the presence of the surface passivation layer 19 can reduce the number of surface defects of the spacing region 13, which is beneficial to the first side of the battery body having a higher passivation effect. Therefore, the size relationship between the width of the first spacing sub-region 15 and the thickness of the surface passivation layer 19 can be set according to actual needs, as long as it can be applied to the back contact battery provided in the embodiments of the present application.

[0075] For example, the ratio between the width of the first spacing sub-region in the second direction and the thickness of the surface passivation layer is P6, and 1000 < P6 < 5000. For example, the ratio P6 can be 1001, 1100, 1200, 1500, 2000, 2500, 3000, 3500, 4000, 4500 or 4999, etc. In this case, the size of the ratio P6 is within the above range, which is beneficial to prevent the width of the first spacing sub-region from being too small due to the too small value of the ratio P6. The application principle of the beneficial effect of preventing the width of the first spacing sub-region from being too small can be referred to the foregoing, which will not be described here. In addition, it can also prevent the width of the first spacing sub-region from being too large and / or the thickness of the surface passivation layer from being too small due to the too large value of the ratio P6, which is beneficial to set the width of the first spacing sub-region and the thickness of the surface passivation layer within a reasonable range, so as to increase the width of the first spacing sub-region relative to the prior art to reduce parasitic absorption and light shielding area of the current collecting electrode, while solving the problem that the area ratio of the first doped region and the second doped region having a field passivation effect is small due to the large width and / or area of the spacing region, which leads to the passivation effect of the first side being poor, and is beneficial to the first side having a lower carrier recombination rate.

[0076] In addition, the material of the surface passivation layer can include any insulating material having a passivation effect, which is not limited here. For example, the material of the surface passivation layer can include at least one of silicon oxide, silicon nitride and aluminum oxide.

[0077] For the first electrode and the second electrode, the specific structure of the first electrode and the second electrode can be determined according to the shape of the first doped region and the second doped region, respectively, which is not limited here.

[0078] For example, as shown in Figure 2As shown, when the first doped regions 11 and the second doped regions 12 are alternately and spacedly distributed in the interdigital manner, the first electrode and the second electrode can only include the current collecting electrodes 14.

[0079] As shown, the first electrode and the second electrode can also include auxiliary bus electrodes 20. The auxiliary bus electrodes 20 included in the first electrode and the auxiliary bus electrodes 20 included in the second electrode are both extended along the second direction and alternately and spacedly distributed along the first direction. The auxiliary bus electrodes 20 included in the first electrode are electrically connected with at least part of the current collecting electrodes 14 included in the first electrode, and the auxiliary bus electrodes 20 included in the second electrode are electrically connected with at least part of the current collecting electrodes 14 included in the second electrode. The current collecting electrodes 14 are disconnected at the intersections with the auxiliary bus electrodes 20 of opposite polarity. Figure 5 Figure 6 As shown, in the first electrode, the same auxiliary bus electrode 20 can be electrically connected with only part of the rows of the current collecting electrodes 14 spacedly distributed along the second direction; and in the second electrode, the auxiliary bus electrode 20 can be electrically connected with only part of the rows of the current collecting electrodes 14 spacedly distributed along the second direction. Alternatively, as shown, in the first electrode, the auxiliary bus electrode 20 can also be electrically connected with all the rows of the current collecting electrodes 14 spacedly distributed along the second direction; and in the second electrode, the auxiliary bus electrode 20 can also be electrically connected with all the rows of the current collecting electrodes 14 spacedly distributed along the second direction.

[0080] As shown, in the first electrode, the same auxiliary bus electrode 20 can be electrically connected with only part of the rows of the current collecting electrodes 14 spacedly distributed along the second direction; and in the second electrode, the auxiliary bus electrode 20 can be electrically connected with only part of the rows of the current collecting electrodes 14 spacedly distributed along the second direction. Alternatively, as shown, in the first electrode, the auxiliary bus electrode 20 can also be electrically connected with all the rows of the current collecting electrodes 14 spacedly distributed along the second direction; and in the second electrode, the auxiliary bus electrode 20 can also be electrically connected with all the rows of the current collecting electrodes 14 spacedly distributed along the second direction. Figure 5 Figure 6 The length of the auxiliary bus electrodes along the second direction and the width of the auxiliary bus electrodes along the first direction can be set according to actual needs, which are not specifically limited here. In some examples, the width of the auxiliary bus electrodes along the first direction can be greater than the width of the current collecting electrodes along the second direction, so as to increase the carrier conduction area of the auxiliary bus electrodes and reduce transmission loss.

[0081] As an example, the width of the at least one auxiliary bus electrode along the first direction can be greater than or equal to 0.05 mm and less than or equal to 300 mm. For example, the width of the at least one auxiliary bus electrode along the first direction can be 0.05 mm, 0.1 mm, 1 mm, 10 mm, 50 mm, 80 mm, 100 mm, 150 mm, 200 mm, 250 mm or 300 mm, etc. Alternatively, the width of the at least one auxiliary bus electrode along the first direction can be greater than or equal to 0.5 mm and less than or equal to 100 mm.

[0082] As an example, the width of the at least one auxiliary bus electrode along the first direction can be greater than or equal to 0.05 mm and less than or equal to 300 mm. For example, the width of the at least one auxiliary bus electrode along the first direction can be 0.05 mm, 0.1 mm, 1 mm, 10 mm, 50 mm, 80 mm, 100 mm, 150 mm, 200 mm, 250 mm or 300 mm, etc. Alternatively, the width of the at least one auxiliary bus electrode along the first direction can be greater than or equal to 0.5 mm and less than or equal to 100 mm.

[0083] ​​The width of the auxiliary bus electrode in the second direction can be the same or different. For example, the width of the auxiliary bus electrode from the middle line to the end in the second direction can gradually decrease. In addition, when the width of the auxiliary bus electrode changes, the width of the part of the first doped region and / or the second doped region located below the corresponding auxiliary bus electrode can also change in the same trend as the width of the auxiliary bus electrode, that is, when the width of the auxiliary bus electrode decreases, the width of the part of the first doped region and / or the second doped region located below the smaller width of the auxiliary bus electrode is also smaller.

[0084] As for the first direction, the spacing between the auxiliary bus electrode and the collector electrode with the opposite conductivity type can be determined according to the anti-creeping requirement between the two in the actual application scenario and the carrier collection capability requirement of the collector electrode, which is not specifically limited here.

[0085] The spacing between the auxiliary bus electrode included in the first electrode and the corresponding collector electrode included in the second electrode in the first direction can be the same as or different from the spacing between the auxiliary bus electrode included in the second electrode and the corresponding collector electrode included in the first electrode in the first direction.

[0086] For example, when the first electrode is a positive electrode and the second electrode is a negative electrode, the spacing between the auxiliary bus electrode included in the first electrode and the corresponding collector electrode included in the second electrode in the first direction can be greater than the spacing between the auxiliary bus electrode included in the second electrode and the corresponding collector electrode included in the first electrode in the first direction. At this time, the spacing between the auxiliary bus electrode included in the second electrode and the corresponding collector electrode included in the first electrode in the first direction is smaller, which is beneficial to increase the length of the collector electrode included in the first electrode and improve the carrier collection capability of the collector electrode included in the first electrode.

[0087] In addition, when the first electrode and the second electrode also include auxiliary bus electrodes, if the auxiliary bus electrodes are burn-through electrodes, at least the regions of the first doped region and the second doped region corresponding to the auxiliary bus electrodes are alternately and spacedly distributed in a finger shape. In the first direction, the strip-shaped doped regions with the same conductivity type in the same row are disconnected at the intersection with the connecting doped region with the opposite conductivity type.

[0088] If the auxiliary bus electrodes are non-burn-through electrodes, the first doped region and the second doped region can be alternately and spacedly distributed in a strip shape, that is, in the region of the auxiliary bus electrode along the length direction which does not intersect with the collector electrode with the same conductivity type, no doped region with the same conductivity type is arranged above. At this time, the auxiliary bus electrode can be electrically isolated from the doped region with the opposite conductivity type and located below itself through a film layer made of an insulating material such as a surface passivation layer. Or, as Figure 5 and Figure 6As shown, when the auxiliary bus electrode 20 is a non-burn-through electrode, the regions in the first doped region 11 and the second doped region 12 that correspond to the auxiliary bus electrode 20 can also be distributed in an interdigitated alternating pattern. Along the first direction, the strip-shaped doped regions that are in the same row and have the same conductivity type are disconnected at the intersection of the connecting doped regions that have the opposite conductivity type to prevent short circuits.

[0089] Within the first and second doped regions, in the areas that are interdigitated and alternately spaced in a finger-like pattern, a second spacer sub-region is defined as the portion of the spacer region located along the first direction between the current collector electrode and its adjacent auxiliary bus electrode with opposite polarity. A third doped sub-region is the portion of the first doped region located below the auxiliary bus electrode included in the first electrode, and a fourth doped sub-region is the portion of the second doped region located below the auxiliary bus electrode included in the second electrode.

[0090] The width of the second spacer sub-region along the first direction can be equal to the width of the third doped sub-region and / or the fourth doped sub-region along the first direction. In this case, the width of the second spacer sub-region is larger, and the distance between the ends of the auxiliary bus electrode and the collector electrode with opposite polarity and whose extension lines intersect is larger, reducing the risk of leakage between the two.

[0091] Or, such as Figure 5 and Figure 6 As shown, the width of the second spacer region 21 along the first direction can also be smaller than the width of the larger of the third doped sub-region 22 and the fourth doped sub-region 23; or, the area of ​​the second spacer region 21 can be smaller than the area of ​​the larger of the third doped sub-region 22 and the fourth doped sub-region 23. In this case, the larger widths of the third doped sub-region 22 and the fourth doped sub-region 23 in the first direction are beneficial for the first doped region 11 and the second doped region 12 to have higher carrier splitting and collection capabilities, which helps to reduce the carrier recombination rate. At the same time, it helps to retain sufficient carrier collection space and improve the current collection capability.

[0092] Furthermore, the width of the third doped sub-region can be equal to the width of the first doped sub-region; or, as... Figure 5 and Figure 6 As shown, the width of the third doped sub-region 22 can be greater than the width of the first doped sub-region 16. In this case, it is beneficial to reduce the leakage risk between the auxiliary bus electrode 20 disposed above the third doped sub-region 22 and the second doped region 12, and to reduce the process difficulty of forming the auxiliary bus electrode 20 above the third doped sub-region 22.

[0093] The width of the fourth doped subregion can be equal to the width of the second doped subregion; or, as... Figure 5 and Figure 6As shown, the width of the fourth doped sub-region 23 is greater than the width of the second doped sub-region 17. In this case, it is beneficial to reduce the risk of leakage between the auxiliary bus electrode 20 arranged above the fourth doped sub-region 23 and the first doped region 11, and to reduce the process difficulty of forming the auxiliary bus electrode 20 above the fourth doped sub-region 23.

[0094] As for the width information of the third doped sub-region, the fourth doped sub-region, and the second interval sub-region along the first direction, the size can be set according to the size of the battery body in the actual application scenario and the actual demand, which is not specifically limited here.

[0095] As a possible implementation, as shown in Figure 8 The first electrode and the second electrode can also include an interconnection structure 24 electrically connected to the current collecting electrode 14, for realizing electrical interconnection between different batteries. The shape of the interconnection structure 24, the distribution and the number of the interconnection structure 24 on the battery body, and the size of the interconnection structure 24 can be set according to the actual demand, which is not specifically limited here.

[0096] The width of the interconnection structure in the second direction can be equal to the width of the current collecting electrode, or can be greater than the width of the current collecting electrode.

[0097] For example, the length of the at least one interconnection structure along the first direction can be 0.05 mm, 0.1 mm, 1 mm, 10 mm, 50 mm, 80 mm, 100 mm, 150 mm, 200 mm, 250 mm, or 300 mm, etc. Alternatively, the length of the at least one interconnection structure along the first direction can be greater than or equal to 0.5 mm and less than or equal to 100 mm.

[0098] For example, the width of the at least one interconnection structure along the second direction can be 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, or 800 μm, etc. Alternatively, the width of the at least one interconnection structure along the second direction can be greater than or equal to 200 μm and less than or equal to 500 μm.

[0099] For example, the area ratio of all the interconnection structures included in the first electrode and / or the second electrode on one side of the first surface can be 0.1 cm 2 , and less than or equal to 100 cm 2 . For example, the area ratio of all the interconnection structures included in the first electrode and / or the second electrode on one side of the first surface can be 0.1 cm 21cm 2 5cm 2 10cm 2 20cm 2 50cm 2 60cm 2 80cm 2 or 100cm 2 etc. Alternatively, the ratio of the area occupied by all the interconnection structures included in the first electrode and / or the second electrode on one side of the first surface can be greater than or equal to 1cm 2 and less than or equal to 50cm 2 .

[0100] For example, in a single unit area, the number of interconnection structures arranged above the first doped region and / or the second doped region can be greater than or equal to 2 and less than or equal to 50.

[0101] For example, in the first surface, the total number of interconnection structures arranged above the first doped region and / or the second doped region can be greater than or equal to 100 and less than or equal to 3000.

[0102] In addition, as Figure 8 shown, the part of the first doped region 11 located below the interconnection structure 24 included in the first electrode is defined as the fifth doped sub-region 25, and the part of the second doped region 12 located below the interconnection structure 24 included in the second electrode is defined as the sixth doped sub-region 26. In this case, when the width of the interconnection structure 24 along the second direction is greater than the width of the collector electrode 14, the width of the fifth doped sub-region 25 is greater than the width of the first doped sub-region 16. The width of the sixth doped sub-region 26 is greater than the width of the second doped sub-region 17, so as to reduce the risk of leakage between the interconnection structure 24 and the opposite doped region, and improve the electrical reliability of the back contact cell.

[0103] As for the width of the fifth doped sub-region and the sixth doped sub-region, it can be determined according to the size of the interconnection structure and the requirement for the double-sided rate of the back contact cell in the actual application scenario, which is not specifically limited here.

[0104] For example, the ratio between the width of the first interval sub-region along the second direction and the width of the larger one of the fifth doped sub-region and the sixth doped sub-region along the second direction can be greater than or equal to one-fiftieth and less than or equal to one-half. For example, taking the case where the width of the fifth doped sub-region along the second direction is greater than or equal to the width of the sixth doped sub-region along the second direction as an example: at this time, the ratio between the width of the first interval sub-region along the second direction and the width of the fifth doped sub-region along the second direction can be one-fiftieth, one-fortieth, one-thirtieth, one-twentieth, one-tenth, one-fifth or one-half, etc.

[0105] For example, the ratio between the area of the first interval sub-region and the area of the larger one of the fifth doped sub-region and the sixth doped sub-region can be greater than or equal to one-fiftieth and less than or equal to one-half. For example, when the area of the fifth doped sub-region is greater than or equal to the area of the sixth doped sub-region, the ratio between the area of the first interval sub-region and the area of the fifth doped sub-region can be one-fiftieth, one-fortieth, one-thirtieth, one-twentieth, one-tenth, one-half, or one-half. The application principle of the beneficial effects in this case is similar to that of the beneficial effects described above, and will not be repeated here.

[0106] The specific width range of the fifth doped sub-region and the sixth doped sub-region can be determined according to the size of the battery body and the size of the first interval sub-region described above, as long as it can be applied to the back contact battery provided in the embodiments of the present application.

[0107] In a second aspect, the embodiments of the present application provide a photovoltaic module, which comprises the back contact battery provided in the first aspect and various implementation manners thereof.

[0108] The beneficial effects of the second aspect and various implementation manners thereof in the embodiments of the present application can be analyzed with reference to the beneficial effects in the first aspect and various implementation manners thereof, which will not be repeated here.

[0109] In the above description, the patterning, etching, and other technical details of each layer are not described in detail. However, those skilled in the art should understand that the layers, regions, and the like with the required shape can be formed by various technical means. In addition, those skilled in the art can also design methods that are not exactly the same as the methods described above in order to form the same structure. In addition, although each embodiment is described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination.

[0110] The embodiments of the present application are described above. However, these embodiments are only for a clearer illustration, and are not intended to limit the scope of the present application. The scope of the present application is defined by the appended claims and their equivalents. Without departing from the scope of the present application, those skilled in the art can make various substitutions and modifications, which should all fall within the scope of the present application.

Claims

1. A back contact cell, characterized in that, The back contact battery comprises: a battery body, and a first electrode and a second electrode arranged on the battery body; the battery body has opposite first and second surfaces; the first surface comprises first and second doped regions and interval regions arranged alternately and spaced apart; the first doped regions are arranged on the first surface and electrically connected with the first surface; the second doped regions are arranged on the second surface and electrically connected with the second surface; the first electrode and the second electrode each comprise a current collecting electrode; the current collecting electrode of the first electrode and the current collecting electrode of the second electrode extend along a first direction and are arranged alternately and spaced apart along a second direction; the first direction is different from the second direction; along the second direction, the interval regions are located between two adjacent current collecting electrodes with opposite polarities, and the portions of the interval regions are first interval sub-regions; the portions of the first doped regions located below the current collecting electrodes of the first electrode are first doped sub-regions, and the portions of the second doped regions located below the current collecting electrodes of the second electrode are second doped sub-regions; the width of the first doped sub-regions is greater than or equal to the width of the second doped sub-regions; the width of at least one first interval sub-region along the second direction is greater than the width of at least one first doped sub-region along the second direction; and / or, the area of at least one first interval sub-region is greater than the area of at least one first doped sub-region; the first electrode and the second electrode further comprise interconnection structures electrically connected with the current collecting electrodes; the portions of the first doped regions located below the interconnection structures of the first electrode are fifth doped sub-regions, and the portions of the second doped regions located below the interconnection structures of the second electrode are sixth doped sub-regions; the width of the interconnection structures along the second direction is greater than the width of the current collecting electrodes; the width of the fifth doped sub-regions is greater than the width of the first doped sub-regions; and the width of the sixth doped sub-regions is greater than the width of the second doped sub-regions. the surface of the interval regions has a velvet structure, and the ratio of the total area of all the interval regions included in the first surface to the total area of the first surface is greater than 50%.

2. The back contact cell of claim 1, wherein, the ratio of the width of at least one first interval sub-region to the sum of the widths of adjacent first and second doped sub-regions is P1; 0.5 < P1 < 3.

3. The back contact cell of claim 1, wherein, and / or, in the back contact battery, the ratio between the total number of the current collecting electrodes of the first electrode and the current collecting electrodes of the second electrode along the second direction and the width of the first interval sub-regions along the second direction is P3, and 0.1 ≤ P3 ≤ 15.

4. The back contact cell of claim 1, wherein, In the second direction, the region between the midlines of two adjacent first doped sub-regions is a unit region, or the region between the midlines of two adjacent second doped sub-regions is a unit region; in the second direction, the ratio between the width of a single first interval sub-region and the width of the unit region is P2, and ; the first doped regions are emitter regions; 5. The back contact cell of claim 1, wherein, the ratio between the cross-sectional area of the first doped sub-regions and the cross-sectional area of the second doped sub-regions is P4, 0.04 < P4 < 30; or, the ratio between the aspect ratio of the first doped sub-regions and the aspect ratio of the second doped sub-regions is P5, 0.04 < P5 < 30. ​ 6. The back contact cell of claim 1, wherein, The first surface of the battery body is provided with a surface passivation layer; the current collecting electrode included in the first electrode is electrically connected with the first doped region through the surface passivation layer, and the current collecting electrode included in the second electrode is electrically connected with the second doped region through the surface passivation layer. The ratio between the width of the first interval sub-region along the second direction and the thickness of the surface passivation layer is P6, and 1000 < P6 < 5000.

7. The back contact cell of claim 1, wherein, The first electrode and the second electrode further include auxiliary bus electrodes; the auxiliary bus electrodes included in the first electrode and the auxiliary bus electrodes included in the second electrode both extend along the second direction and are alternately and intervally distributed along the first direction; the auxiliary bus electrodes included in the first electrode are electrically connected with at least part of the current collecting electrodes included in the first electrode, and the auxiliary bus electrodes included in the second electrode are electrically connected with at least part of the current collecting electrodes included in the second electrode; the current collecting electrodes are disconnected at the intersections of the auxiliary bus electrodes with opposite polarities to themselves; along the first direction, the part of the current collecting electrode between the interval region and the auxiliary bus electrode adjacent to itself and opposite in polarity is a second interval sub-region; the part of the first doped region below the auxiliary bus electrodes included in the first electrode is a third doped sub-region, and the part of the second doped region below the auxiliary bus electrodes included in the second electrode is a fourth doped sub-region. The width of the second interval sub-region along the first direction is smaller than the width of the larger one of the third doped sub-region and the fourth doped sub-region; or, the area of the second interval sub-region is smaller than the area of the larger one of the third doped sub-region and the fourth doped sub-region.

8. The back contact cell of claim 7, wherein, The width of the third doped sub-region is greater than the width of the first doped sub-region. And / or, the width of the fourth doped sub-region is greater than the width of the second doped sub-region.

9. The back contact cell of claim 1, wherein, The first electrode and the second electrode further include interconnection structures electrically connected with the current collecting electrodes; the part of the first doped region below the interconnection structures included in the first electrode is a fifth doped sub-region, and the part of the second doped region below the interconnection structures included in the second electrode is a sixth doped sub-region; The ratio between the width of the first interval sub-region along the second direction and the width of the larger one of the fifth doped sub-region and the sixth doped sub-region along the second direction is greater than or equal to one-fiftieth and less than or equal to one-half; and / or, the ratio between the area of the first interval sub-region and the area of the larger one of the fifth doped sub-region and the sixth doped sub-region is greater than or equal to one-fiftieth and less than or equal to one-half.

10. A photovoltaic module, characterized by, A back contact battery comprising any one of the back contact batteries according to claims 1-9.

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