Back contact battery and photovoltaic module

Abstract

The utility model discloses a back contact cell and a photovoltaic assembly, relates to the field of photovoltaic technology, and aims to reasonably set the area proportion between a first contact region and an emitter region and between the first contact region and a first doped region. The back contact battery comprises a semiconductor substrate, a surface passivation layer, a first electrode and a second electrode. The second doped region is an emitter region. The surface passivation layer is formed on the first doped region and the second doped region on one side of the backlight surface of the semiconductor substrate. The first electrode penetrates through the surface passivation layer through the first conductive window and is in ohmic contact with the first doped region. And the second electrode penetrates through the surface passivation layer through the second conductive window and is in ohmic contact with the second doped region. The area, exposed through the first conductive window, in the first doped area is a first contact area. The area ratio of the first contact region to the emitter region is greater than or equal to 0.93% and less than or equal to 4.42%. The area ratio of the first contact region to the first doped region is greater than or equal to 2.16% and less than or equal to 17.7%.

Description

[0001] This application claims priority of the Chinese patent application number 202311542462.1 filed with the Patent Office of China on November 20, 2023, with the invention name “A Back Contact Cell and Photovoltaic Module”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The utility model relates to the technical field of photovoltaics, in particular to a back contact battery and a photovoltaic component. Background Art

[0003] A back-contact cell refers to a solar cell in which the light-facing side of the cell has no electrode, and both the positive and negative electrodes are arranged on the backlight side of the cell. This can reduce the shading of the electrode on the cell, increase the short-circuit current of the cell, and improve the energy conversion efficiency of the cell.

[0004] However, existing back-contact cells have a first doped region and a second doped region of opposite conductivity types on the backside, with the second doped region serving as the emitter region. Furthermore, the first electrode in the back-contact cell makes ohmic contact with the first doped region through a first conductive window in the surface passivation layer, and the second electrode makes ohmic contact with the second doped region through a second conductive window in the surface passivation layer. However, the area ratio between the area of ​​the first doped region exposed through the first conductive window and the emitter region is irrational, resulting in poor photoelectric conversion efficiency in the back-contact cell. Utility Model Content

[0005] The purpose of the present utility model is to provide a back-contact cell and photovoltaic module, which are used to reasonably set the area ratio between the area exposed to the outside through the first conductive window in the first doping region and the emitter region, so as to improve the photoelectric conversion efficiency of the back-contact cell.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a back-contact battery, comprising: a semiconductor substrate, a surface passivation layer, a first electrode, and a second electrode. The back-light surface of the semiconductor substrate comprises a first doped region and a second doped region of opposite conductivity types, with the second doped region being an emitter region. The first doped regions and at least a portion of the second doped regions are alternately distributed. A surface passivation layer is formed on the first doped region and the second doped region on the back-light side of the semiconductor substrate. First and second conductive windows are provided through the surface passivation layer. The first and second electrodes are formed on the back-light side of the semiconductor substrate and are insulated from each other. The projection of the first electrode on the semiconductor substrate is located within the first doped region, and the first electrode penetrates the surface passivation layer through the first conductive window and forms ohmic contact with the first doped region. The projection of the second electrode on the semiconductor substrate is located within the second doped region, and the second electrode penetrates the surface passivation layer through the second conductive window and forms ohmic contact with the second doped region. The region of the first doped region exposed through the first conductive window constitutes the first contact region. An area ratio of the first contact region to the emitter region is greater than or equal to 0.93% and less than or equal to 4.42%; an area ratio of the first contact region to the first doping region is greater than or equal to 2.16% and less than or equal to 17.7%.

[0007] When the above technical solution is adopted, in the back-contact battery provided by the present invention, the first doped region and at least part of the second doped region are alternately distributed, which means that the first electrode and at least part of the second electrode are alternately distributed, that is, a second electrode with opposite polarity is also provided between adjacent first electrodes, and a first electrode with opposite polarity is also provided between adjacent second electrodes. Compared with the double-sided contact battery, the spacing between adjacent first electrodes or the spacing between adjacent second electrodes is larger, and the carrier transmission distance of the corresponding conductive type is longer before it can be collected by the first electrode or the second electrode. In order to overcome the problem of long transmission distance, the area ratio of the first contact region to the first doped region should be designed to be higher. Based on this, it can be understood that when the spacing between adjacent first electrodes becomes larger, the carrier transmission distance of the corresponding conductive type will also become larger before it can be collected by the first electrode. The present application overcomes the problem of increased power loss due to increased carrier transmission distance by increasing the area of ​​the first contact region to the first doped region. On the other hand, the area of ​​the first contact region also affects the area of ​​the emitter region. Compared with double-sided contact cells, the first doped region and the second doped region of the back contact cell are both located on the same surface. The area of ​​the first contact region in the first doped region becomes larger, and the area of ​​the second doped region, i.e., the emitter region, may become smaller, affecting the carrier separation effect. The present application solves the carrier transport problem while also satisfying the carrier separation effect and increasing the probability of carrier collection by designing the area ratio of the first contact region and the emitter region. In addition, the area of ​​the first contact region also affects the passivation effect. The surface passivation layer is used to chemically passivate the backlight side of the semiconductor substrate to reduce the carrier recombination rate on the backlight side. Within a certain range, the passivation effect of the surface passivation layer on the backlight side is proportional to the actual formation area of ​​the surface passivation layer on the backlight side of the semiconductor substrate. In addition, the first electrode formed on the backlight side needs to penetrate the surface passivation layer through the first conductive window to make ohmic contact with the first doped region, and the second electrode needs to penetrate the surface passivation layer through the second conductive window to make ohmic contact with the second doped region, and the area of ​​the first doped region exposed to the outside through the first conductive window is the first contact region. In this case, after forming the first and second electrodes, the actual surface passivation layer area on the backlight side needs to be reduced by the area of ​​the first and second conductive windows penetrating the surface passivation layer. Based on this, it can be understood that the larger the area of ​​the first electrode penetrating the surface passivation layer, the poorer the passivation effect of the surface passivation layer on the backlight side. Furthermore, the larger the area of ​​the first electrode penetrating the surface passivation layer, the greater the distribution density of the first electrodes, resulting in a lower series resistance of the back-contact battery.In the above case, under the premise that other factors remain unchanged, when the area ratio of the first contact region and the emitter region is greater than or equal to 0.93% and less than or equal to 4.42%, and the area ratio of the first contact region and the first doping region is greater than or equal to 2.16% and less than or equal to 17.7%, the area ratio of the first contact region and the first doping region, the area ratio of the first contact region and the emitter region, the passivation area and the contact area are reasonably set, so that the carrier separation, carrier transport, surface passivation effect and series resistance are optimized, which is beneficial to improve the photoelectric conversion efficiency of the back contact battery.

[0008] As a possible implementation scheme, the first electrode and the second electrode each include a plurality of bus electrodes and a plurality of collector electrodes. The bus electrodes included in the first electrode and the bus electrodes included in the second electrode both extend along the first direction and are spaced apart along the second direction, which is different from the first direction. The collector electrodes included in the first electrode and the collector electrodes included in the second electrode both extend along the second direction and are spaced apart along the first direction. At least a portion of each collector electrode included in the first electrode penetrates the surface passivation layer and is in ohmic contact with the first doped region. At least a portion of each collector electrode included in the second electrode penetrates the surface passivation layer and is in ohmic contact with the second doped region. Each bus electrode is connected to a collector electrode of the same polarity and is insulated from a collector electrode of the opposite polarity. In this case, the first electrode and the second electrode both include a collector electrode for collecting carriers, and also include a bus electrode for at least collecting and conducting the carriers collected by the collector electrodes of the same polarity. Based on this, since the bus electrode has a smaller resistivity than the collector electrode, it is beneficial to improve the conductivity of the first electrode and the second electrode, reduce transmission loss, and thus help improve the photoelectric conversion efficiency of the back contact battery.

[0009] As a possible implementation, the portion of the first doped region exposed through the first conductive window that makes ohmic contact with each collector electrode included in the first electrode serves as the second contact region. The portion of the second doped region exposed through the second conductive window that makes ohmic contact with each collector electrode included in the second electrode serves as the third contact region. The area ratio of the second contact region to the first doped region is different from the area ratio of the third contact region to the second doped region.

[0010] When the above technical solution is adopted, in the actual application process, the doping concentrations of the first doping region and the second doping region are different, so the transmission resistance of the carriers in the two regions is also different, which will cause the problem of current mismatch. The present application balances the carrier collection capabilities of the first doping region and the second doping region by making the corresponding contact regions have different area ratios in the doping region, thereby solving the problem of current mismatch. Based on this, the area ratio of the second contact region to the first doping region, as well as the area ratio of the third contact region to the second doping region, can be set according to the area ratios of the first doping region and the second doping region on the backlight side, respectively, to ensure that the transmission loss of the corresponding carriers to the collector electrode included in the adjacent first electrode, and the transmission loss of the corresponding carriers to the collector electrode included in the adjacent second electrode are both small and adaptive. In addition, the materials and widths of collector electrodes with different polarities can be set differently (for example, the collector electrodes included in the negative electrode are usually made of silver material and have a smaller width; while the collector electrodes included in the positive electrode are usually made of aluminum material and have a larger width). At this time, the proportion of the second contact area in the first doping area and the proportion of the third contact area in the second doping area are set to different values, that is, the contact ratios of collector electrodes with different widths and corresponding doping areas are set to different ratios, ensuring that collector electrodes with opposite polarities and different widths have higher carrier collection capabilities, and that the carriers collected by the first doping area and the second doping area are adapted.

[0011] As a possible implementation, the area ratio of the second contact region to the first doped region is greater than or equal to 2.16% and less than or equal to 17.7%. In this case, the area ratio of the second contact region to the first doped region is equal to the area ratio of the first contact region to the first doped region. In this case, only the collector electrode of the first electrode is electrically connected to the first doped region, and the bus electrode included in the first electrode does not directly electrically contact the first doped region.

[0012] As a possible implementation scheme, when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, the area ratio of the third contact region and the second doping region is greater than or equal to 0.78% and less than or equal to 13.15%, or, when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the area ratio of the third contact region and the second doping region is greater than or equal to 0.78% and less than or equal to 17.38%.

[0013] When the above technical solution is adopted, the area ratio of the third contact region and the second doped region is within the above range, which can prevent the transmission loss from being large due to the small ratio. In addition, it can also prevent the metal composite loss from being high and the surface passivation effect from being small due to the large ratio. The balance between the surface passivation effect, series resistance and transmission loss can be further improved, and the photoelectric conversion efficiency of the back contact battery can be further improved. In addition, the above third contact region is the region where the collector electrode included in the second electrode contacts the second doped region. When the conductivity type of the second doped region is N-type, the second electrode is a negative electrode. When the conductivity type of the second electrode is P-type, the second electrode is a positive electrode. Based on this, it can be seen from the above two area ratios that when the second electrode is a positive electrode, the upper limit of the area ratio of the third contact region to the second doped region is large. At this time, aluminum material can be used to manufacture the collector electrode included in the second electrode to reduce the consumption of metal slurry, which is conducive to controlling the manufacturing cost of the back contact battery.

[0014] As a possible implementation, when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, the area ratio between the second contact region and the third contact region is greater than or equal to 33.6% and less than or equal to 120%. Alternatively, when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the area ratio between the second contact region and the third contact region is greater than or equal to 25.43% and less than or equal to 120%.

[0015] When the above technical solution is adopted, when the conductivity type of the first doped region is P type and the conductivity type of the second doped region is N type, the first electrode is the positive electrode and the second electrode is the negative electrode; at this time, the area ratio between the second contact region and the third contact region is within the above range, which can prevent the holes in the semiconductor substrate of the back contact battery from being collected and exported in time by the first electrode when the back contact battery is in a working state due to the small ohmic contact area between the collector electrode included in the positive electrode and the first doped region, which is beneficial to reducing the carrier recombination rate on the backlight side and further improving the photoelectric conversion efficiency of the back contact battery; in addition, the area ratio between the above second contact region and the third contact region has a larger optional range, which is beneficial to improving the applicability of the back contact battery provided by the utility model in different application scenarios. As for the beneficial effect of the area ratio between the second contact region and the third contact region being greater than or equal to 25.43% and less than or equal to 120% when the conductivity type of the first doped region is N-type and the conductivity type of the second doped region is P-type, you can refer to the beneficial effect analysis of the area ratio between the second contact region and the third contact region being greater than or equal to 33.6% and less than or equal to 120% when the conductivity type of the first doped region is P-type and the conductivity type of the second doped region is N-type, which will not be repeated here.

[0016] As a possible implementation scheme, when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area is greater than or equal to 5% and less than or equal to 22.5%. In this case, when the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area is within the above range, it can prevent the contact resistance between the first electrode and the semiconductor substrate from being large due to the small ohmic contact area between each collector electrode included in the first electrode and the first doping region, which is beneficial to improving the contact performance between the first electrode and the semiconductor substrate. In addition, it can also prevent the actual formation area of ​​the surface passivation layer on the backlight side from being small due to the large surface area of ​​each collector electrode included in the first electrode penetrating the surface passivation layer due to the large ratio, thereby ensuring that the surface passivation layer has a relatively high surface passivation effect on the backlight side.

[0017] As a possible implementation solution, when the conductivity type of the first doped region is N-type and the conductivity type of the second doped region is P-type, the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area is greater than or equal to 12% and less than or equal to 72%. The beneficial effects of this situation can be referred to the beneficial effects of the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area being greater than or equal to 5% and less than or equal to 22.5% when the conductivity type of the first doped region is P-type and the conductivity type of the second doped region is N-type, and will not be repeated here.

[0018] As a possible implementation, when at least a portion of a bus electrode included in the first electrode penetrates the surface passivation layer and is in ohmic contact with the first doped region, the portion of the first doped region exposed through the first conductive window that is in ohmic contact with each bus electrode included in the first electrode constitutes the fourth contact region. Furthermore, the ratio of the area of ​​each bus electrode included in the first electrode to its own cross-sectional area is greater than or equal to 0.67% and less than or equal to 100%.

[0019] When the above technical solution is adopted, in addition to each collector electrode included in the first electrode being able to penetrate the surface passivation layer and form ohmic contact with the first doped region, the bus electrode included in the first electrode can also penetrate the surface passivation layer and form ohmic contact with the first doped region, providing another possible solution for the contact method between the first electrode and the first doped region, which is conducive to expanding the scope of application of the back-contact battery provided by the utility model. In addition, the ratio of the area of ​​the fourth contact region corresponding to each bus electrode included in the first electrode to its own cross-sectional area has a large range of optional values, and the appropriate value can be determined according to the actual application scenario, which is conducive to expanding the applicability of the back-contact battery provided by the utility model in different application scenarios.

[0020] As a possible implementation, when the conductivity type of the first doped region is P-type and the conductivity type of the second doped region is N-type, the area ratio between the fourth contact region and the second contact region is greater than or equal to 1.23% and less than or equal to 5.05%. In this case, the area of ​​the collector electrode included in the first electrode in ohmic contact with the first doped region accounts for the vast majority of the total area of ​​the first doped region exposed through the first conductive window. Based on this, because the cross-sectional area of ​​the collector electrode is generally smaller than the cross-sectional area of ​​the bus electrode, when the area ratio between the fourth contact region and the second contact region is greater than or equal to 1.23% and less than or equal to 5.05%, the area of ​​the bus electrode included in the first electrode in ohmic contact with the first doped region is smaller, which helps reduce the number of bus electrodes included in the first electrode, thereby reducing the light-shielding area of ​​the bus electrode included in the first electrode, and thus helps allow more light to pass through the backlight surface of the back-contact cell and be utilized by the semiconductor substrate, thereby improving the photoelectric conversion efficiency of the back-contact cell.

[0021] As a possible implementation solution, when the conductivity type of the first doped region is N-type and the conductivity type of the second doped region is P-type, the area ratio between the fourth contact region and the second contact region is greater than or equal to 1.23% and less than or equal to 6.17%. The beneficial effects in this case can be referred to the beneficial effects of the area ratio between the fourth contact region and the second contact region being greater than or equal to 1.23% and less than or equal to 5.05% when the conductivity type of the first doped region is P-type and the conductivity type of the second doped region is N-type, and will not be repeated here.

[0022] As a possible implementation solution, along the first direction, the width of each second contact region is greater than or equal to 28 μm and less than or equal to 120 μm.

[0023] When using the above technical solution, the width of each second contact region along the first direction is within the above range. This can prevent the contact resistance between each collector electrode included in the first electrode and the semiconductor substrate from being large due to the smaller area of ​​the second contact region caused by the smaller width, thereby improving the transmission performance of the first electrode and reducing transmission loss. In addition, it can also prevent the area of ​​each collector electrode included in the first electrode penetrating the surface passivation layer from being large due to the larger width, ensuring that the surface passivation layer has a high passivation effect on the backlight side.

[0024] As a possible implementation solution, along the first direction, a width of a portion of the first doping region corresponding to a portion below each collector electrode included in the first electrode is greater than or equal to 190 μm and less than 260 μm.

[0025] When the above technical solution is adopted, along the first direction, the width of the portion below each collector electrode included in the first electrode corresponding to the first doping region is within the above range, which can prevent the collector electrode included in the first electrode from overlapping with the second doping region with the opposite polarity due to the smaller width of the portion below each collector electrode included in the first doping region corresponding to the first electrode, thereby ensuring that the back contact battery has high electrical reliability. In addition, it can also prevent the area of ​​the second doping region located on the backlight side together with the first doping region from being small due to the larger width of the portion below each collector electrode included in the first doping region corresponding to the first electrode, thereby ensuring that the second doping region serving as the emitter region has a relatively large area on the backlight side, which is beneficial to increasing the strength of the built-in electric field, reducing the carrier recombination rate on the backlight side, and further improving the photoelectric conversion efficiency of the back contact battery.

[0026] As a possible implementation scheme, along the first direction, the width of each second contact region is the first width, the width of the first doped region located below each collector electrode included in the first electrode is the second width, and the ratio of the second width to the first width is greater than or equal to 475% and less than or equal to 650%.

[0027] When the above technical solution is adopted, when the ratio of the second width to the first width is small, the second width can be smaller or the first width can be larger; and when the ratio of the second width to the first width is large, the second width can be larger or the first width can be smaller. Based on this, when the ratio of the second width to the first width is within the above range, it can prevent the second width from being smaller and / or the first width from being larger due to the small ratio of the second width to the first width, and it can also prevent the second width from being larger and / or the first width from being smaller due to the large ratio of the second width to the first width. The effects of preventing the first width from being larger or smaller, and preventing the second width from being larger or smaller can be referred to above and will not be repeated here.

[0028] As a possible implementation, along the first direction, of all the collecting electrodes included in the first electrode and the second electrode, the two outer collecting electrodes are the collecting electrodes included in the second electrode, and the two outer collecting electrodes are continuous collecting electrodes. Of all the collecting electrodes included in the first electrode and the second electrode, except for the two outer collecting electrodes, the remaining collecting electrodes are discontinuous collecting electrodes, and each discontinuous collecting electrode is disconnected at the intersection with the bus electrode of opposite polarity.

[0029] When the above technical solution is adopted, the projection of the second electrode on the semiconductor substrate is located within the second doped region. Based on this, when, along the first direction, of all the collector electrodes included in the first electrode and the second electrode, the two collector electrodes located on the outer side are the collector electrodes included in the second electrode, and the two collector electrodes located on the outer side are continuous collector electrodes, the second doped regions located on different areas on the backlight side of the semiconductor substrate are connected to each other. At this time, the second doped region surrounds at least one first doped region, which is beneficial to increasing the area ratio of the second doped region serving as the emitter region on the backlight side, which is beneficial to increasing the strength of the built-in electric field, reducing the carrier recombination rate on the backlight side, and further improving the photoelectric conversion efficiency of the back-contact battery.

[0030] As a possible implementation, the width of the collector electrode included in the first electrode is different from the width of the collector electrode included in the second electrode. In this case, the collector electrode included in the first electrode and the collector electrode included in the second electrode, which have different polarities, can be manufactured using different conductive materials, which helps reduce metal slurry consumption and control the manufacturing cost of the back-contact battery.

[0031] As a possible implementation solution, the area ratio between the first doping region and the second doping region is greater than or equal to 2:8 and less than or equal to 3:7.

[0032] When the above technical solution is adopted, the area ratio between the first doping region and the second doping region is within the above range, which can prevent the corresponding conductive type of carriers in the semiconductor substrate from being unable to be transmitted to the first electrode in time through the first doping region due to the smaller area between the first doping region and the second doping region; in addition, it can also prevent the area ratio of the second doping region from being smaller due to the larger area between the first doping region and the second doping region, ensuring that the second doping region serving as the emitter region has a relatively large area on the backlight side, which is conducive to increasing the strength of the built-in electric field, further reducing the carrier recombination rate on the backlight side, and thereby improving the photoelectric conversion efficiency of the back-contact battery.

[0033] In a second aspect, the present invention further provides a photovoltaic module, which includes a back-contact cell array formed by back-contact cells provided by the first aspect and various implementations thereof through conductive interconnects.

[0034] The beneficial effects of the second aspect of the present invention and its various implementations can be analyzed with reference to the beneficial effects of the first aspect and its various implementations, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0036] Figure 1 Schematic diagram of the distribution relationship between the first doping region and the second doping region on the backlight side in the embodiment of the utility model Figure 1 ;

[0037] Figure 2 Schematic diagram of the distribution relationship between the first doping region and the second doping region on the backlight side in the embodiment of the utility model Figure 2 ;

[0038] Figure 3 Schematic diagram of the distribution relationship between the first doping region and the second doping region on the backlight side in the embodiment of the utility model Figure 3 ;

[0039] Figure 4 Schematic diagram of the distribution relationship between the first electrode and the second electrode on the backlight side in the embodiment of the utility model Figure 1 ;

[0040] Figure 5 Schematic diagram of the distribution relationship between the first electrode and the second electrode on the backlight side in the embodiment of the utility model Figure 2 ;

[0041] Figure 6 Schematic diagram of the distribution relationship between the first electrode and the second electrode on the backlight side in the embodiment of the utility model Figure 3 ;

[0042] Figure 7 : This is a simulation test relationship diagram between the area ratio of the first contact region and the emitter region and the conversion efficiency in an embodiment of the present utility model;

[0043] Figure 8 A simulation test relationship diagram between the width of the portion below each collector electrode included in the first electrode and the conversion efficiency in the embodiment of the utility model corresponding to the first doping region;

[0044] Figure 9This is a simulation test relationship diagram between the area ratio between the second contact region and the third contact region and the conversion efficiency when the conductivity type of the first doped region is P-type and the conductivity type of the second doped region is N-type in an embodiment of the present invention;

[0045] Figure 10 1 is a simulation test relationship diagram between the area ratio between the second contact region and the third contact region and the conversion efficiency when the conductivity type of the first doped region is N-type and the conductivity type of the second doped region is P-type in an embodiment of the present invention;

[0046] Figure 11 This is a simulation test relationship diagram between the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area and the conversion efficiency when the conductivity type of the first doped region is P-type and the conductivity type of the second doped region is N-type in an embodiment of the present invention;

[0047] Figure 12 This is a simulation test relationship diagram between the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area and the conversion efficiency when the conductivity type of the first doped region is N-type and the conductivity type of the second doped region is P-type in an embodiment of the present invention;

[0048] Figure 13 A simulation test relationship diagram between the ratio of the area of ​​the fourth contact region corresponding to each bus electrode included in the first electrode to its own cross-sectional area and the conversion efficiency in an embodiment of the utility model;

[0049] Figure 14 1 is a simulation test relationship diagram between the area ratio between the fourth contact region and the second contact region and the conversion efficiency when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type in an embodiment of the present invention;

[0050] Figure 15 1 is a simulation test relationship diagram between the area ratio between the fourth contact region and the second contact region and the conversion efficiency when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type in an embodiment of the present invention;

[0051] Figure 16 1 is a simulation test relationship diagram between the width of each second contact region and the conversion efficiency in an embodiment of the present invention.

[0052] Reference numerals: 11 is a first doping region, 12 is a second doping region, 13 is a first electrode, 14 is a second electrode, 15 is a bus electrode, and 16 is a collecting electrode. DETAILED DESCRIPTION

[0053] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0054] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments of the present disclosure. These figures are not drawn to scale, and for the purpose of clarity, certain details are exaggerated and certain details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0055] In the context of this disclosure, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intervening layer / element between them. Furthermore, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element. To further clarify the technical problems, technical solutions, and beneficial effects to be solved by the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the present invention and are not intended to limit the present invention.

[0056] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of this utility model, "plurality" means two or more, unless otherwise specifically defined. "Several" means one or more, unless otherwise specifically defined.

[0057] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0058] At present, solar cells are used more and more widely as a new energy alternative. Among them, photovoltaic solar cells are devices that convert sunlight energy into electrical energy. Specifically, solar cells use the principle of photovoltaics to generate carriers, and then use electrodes to lead out the carriers, thereby facilitating the effective use of electrical energy. Among them, when the positive and negative electrodes included in the solar cell are both located on the back of the solar cell, the solar cell is a back contact cell. Because the front of the back contact cell is not affected by the metal electrode, it has a higher short-circuit current I sc , which is one of the current technical directions for achieving high-efficiency crystalline silicon cells.

[0059] Specifically, existing back-contact cells typically include a semiconductor substrate, a surface passivation layer, a first electrode, and a second electrode. The backlight surface of the semiconductor substrate has alternating first and second doped regions. The first and second doped regions have opposite conductivity types, and the second doped region serves as an emitter region. The surface passivation layer is formed on the backlight side of the semiconductor substrate. The first and second electrodes are located on the backlight side of the semiconductor substrate and are insulated from each other. Specifically, the projection of the first electrode on the semiconductor substrate is located within the first doped region and forms ohmic contact with the first doped region through a first conductive window provided in the surface passivation layer. The projection of the second electrode on the semiconductor substrate is located within the second doped region and forms ohmic contact with the second doped region through a second conductive window provided in the surface passivation layer. Therefore, when the first doped region is a P region and the second doped region is an N region, the first electrode is a positive electrode and the second electrode is a negative electrode. When the second doped region is an N region and the first doped region is a P region, the first electrode is a negative electrode and the second electrode is a positive electrode.

[0060] However, in the existing back-contact battery, the area ratio between the area of ​​the first doped region exposed to the outside through the first conductive window and the emitter region is set unreasonably, which makes the area of ​​the film-opening area set in the surface passivation layer unreasonable, thereby affecting the passivation effect of the surface passivation layer on the backlight side and the series resistance of the solar cell, resulting in poor photoelectric conversion efficiency of the back-contact battery. Specifically, the larger the film-opening area, the worse the passivation effect of the surface passivation layer on the backlight side. The larger the film-opening area, the greater the distribution density of the first electrode and / or the second electrode, and the smaller the series resistance of the back-contact battery. Based on this, when the area ratio of the above two contact areas is set unreasonably, it is difficult to achieve a balance between the surface passivation effect and the series resistance, which in turn makes the photoelectric conversion efficiency of the back-contact battery poor.

[0061] In order to solve the above technical problems, in the first aspect, the embodiment of the present invention provides a back contact battery. Specifically, the back contact battery provided by the embodiment of the present invention includes: a semiconductor substrate, a surface passivation layer, a first electrode and a second electrode. Figures 1 to 3As shown, the backlight side of the semiconductor substrate has a first doping region 11 and a second doping region 12 of opposite conductivity types, and the second doping region 12 is an emitter region. The first doping regions 11 and at least part of the second doping regions 12 are alternately distributed. A surface passivation layer is formed on the first doping region 11 and the second doping region 12 on the backlight side of the semiconductor substrate. A first conductive window and a second conductive window are provided through the surface passivation layer. Figures 4 to 6 As shown, the first electrode 13 and the second electrode 14 are formed on the backlight side of the semiconductor substrate, and the first electrode 13 and the second electrode 14 are insulated from each other. The projection of the first electrode 13 on the semiconductor substrate is located in the first doping region, and the first electrode 13 penetrates the surface passivation layer through the first conductive window and is in ohmic contact with the first doping region. The projection of the second electrode 14 on the semiconductor substrate is located in the second doping region, and the second electrode 14 penetrates the surface passivation layer through the second conductive window and is in ohmic contact with the second doping region. Among them, the area of ​​the first doping region exposed to the outside through the first conductive window is the first contact region. The area ratio of the first contact region to the emitter region is greater than or equal to 0.93% and less than or equal to 4.42%; the area ratio of the first contact region to the first doping region is greater than or equal to 2.16% and less than or equal to 17.7%.

[0062] It should be noted that the back-contact cell provided in the embodiments of the present invention may be a whole-piece back-contact cell or a sliced ​​back-contact cell (such as a half-sliced ​​back-contact cell or a third-sliced ​​back-contact cell). The whole-piece back-contact cell may be a whole-piece cell that does not require slicing; alternatively, the whole-piece back-contact cell may include at least two slice units with a symmetrical electrode design; alternatively, the whole-piece back-contact cell may include at least two slice units with an asymmetric electrode design.

[0063] Furthermore, the aforementioned ohmic contact between the first electrode and the first doped region refers to direct ohmic contact between the portion of the first electrode that penetrates the surface passivation layer and the first doped region. Therefore, the area of ​​the first contact region is the cross-sectional area of ​​the portion of the first electrode that penetrates the surface passivation layer. In other words, the area of ​​the first contact region is the cross-sectional area of ​​the first conductive window.

[0064] Under the condition of adopting the above technical solution, in the back contact battery provided by the embodiment of the present invention, the first doped region and at least part of the second doped region are alternately distributed, which means that the first electrode and at least part of the second electrode are alternately distributed, that is, a second electrode with opposite polarity is also provided between adjacent first electrodes, and a first electrode with opposite polarity is also provided between adjacent second electrodes. Compared with the double-sided contact battery, the spacing between adjacent first electrodes or the spacing between adjacent second electrodes is larger, and the carrier transmission distance of the corresponding conductive type is longer before it can be collected by the first electrode or the second electrode. In order to overcome the problem of long transmission distance, the area ratio of the first contact region to the first doped region should be designed to be higher. Based on this, it can be understood that when the spacing between adjacent first electrodes becomes larger, the carrier transmission distance of the corresponding conductive type will also become larger before it can be collected by the first electrode. The present application overcomes the problem of increased power loss due to the increase in carrier transmission distance by increasing the area of ​​the first contact region to the first doped region. On the other hand, the area of ​​the first contact region also affects the area of ​​the emitter region. Compared with double-sided contact cells, the first doped region and the second doped region of the back contact cell are both located on the same surface. The area of ​​the first contact region in the first doped region becomes larger, and the area of ​​the second doped region, i.e., the emitter region, may become smaller, affecting the carrier separation effect. The present application solves the carrier transport problem while also satisfying the carrier separation effect and increasing the probability of carrier collection by designing the area ratio of the first contact region and the emitter region. In addition, the area of ​​the first contact region also affects the passivation effect. The surface passivation layer is used to chemically passivate the backlight side of the semiconductor substrate to reduce the carrier recombination rate on the backlight side. Within a certain range, the passivation effect of the surface passivation layer on the backlight side is proportional to the actual formation area of ​​the surface passivation layer on the backlight side of the semiconductor substrate. In addition, the first electrode formed on the backlight side needs to pass through the surface passivation layer through the first conductive window and make ohmic contact with the first doped region. The second electrode needs to pass through the surface passivation layer through the second conductive window and make ohmic contact with the second doped region. The area of ​​the first doped region exposed to the outside through the first conductive window is the first contact region. In this case, after forming the first electrode and the second electrode, the actual formation area of ​​the surface passivation layer on the backlight side needs to be subtracted from the area of ​​the first conductive window and the second conductive window penetrating the surface passivation layer. Based on this, it can be understood that the larger the area of ​​the first electrode penetrating the surface passivation layer, the worse the passivation effect of the surface passivation layer on the backlight side. The larger the area of ​​the first electrode penetrating the surface passivation layer, the greater the distribution density of the first electrode, which makes the series resistance of the back contact battery smaller. In the above case, under the premise that other factors remain unchanged, such as Figure 7As shown, when the area ratio of the first contact region and the emitter region is greater than or equal to 0.93% and less than or equal to 4.42%, and the area ratio of the first contact region and the first doping region is greater than or equal to 2.16% and less than or equal to 17.7%, the area ratio of the first contact region and the first doping region, the area ratio of the first contact region and the emitter region, the passivation area and the contact area are reasonably set, so that the carrier separation, carrier transport, surface passivation effect and series resistance are optimized, which is beneficial to improve the photoelectric conversion efficiency of the back contact battery.

[0065] In actual application, the embodiment of the present invention does not impose any specific restrictions on the structure and material of the above-mentioned semiconductor substrate, as long as it can be applied to the back contact battery provided by the embodiment of the present invention.

[0066] Exemplarily, the semiconductor base may include a semiconductor substrate, and a first doped semiconductor layer and a second doped semiconductor layer located on the backlight side of the semiconductor substrate. The first doped semiconductor layer and the second doped semiconductor layer have opposite conductivity types. The first doped semiconductor layer may be located in the semiconductor substrate or on a partial area of ​​the backlight side of the semiconductor substrate; and the first doped region is the region of the first doped semiconductor layer facing away from the semiconductor substrate. The second doped semiconductor layer may be located in the semiconductor substrate or on a partial area of ​​the backlight side of the semiconductor substrate; and the second doped region is the region of the second doped semiconductor layer facing away from the semiconductor substrate. Secondly, the first doped semiconductor layer (or first contact region) and / or the second doped semiconductor layer may be formed by diffusion, ion implantation, or sintering of an electrode paste used to manufacture the first electrode and / or the second electrode.

[0067] Specifically, in terms of conductivity type, the second doped region is an emitter region, and therefore has a conductivity type opposite to that of the semiconductor substrate. The first doped region and the second doped region have opposite conductivity types, and therefore have the same conductivity type as the semiconductor substrate. Therefore, when the semiconductor substrate is a P-type semiconductor substrate, the conductivity type of the first doped region is P-type, and the conductivity type of the second doped region is N-type. When the semiconductor substrate is an N-type semiconductor substrate, the conductivity type of the first doped region is N-type, and the conductivity type of the second doped region is P-type.

[0068] Secondly, in terms of materials, the above-mentioned semiconductor substrate can be made of semiconductor materials such as silicon, silicon germanium, germanium or gallium arsenide. When the first doped semiconductor layer is formed on a partial area of ​​the backlight surface of the semiconductor substrate, the material of the first doped semiconductor layer can be semiconductor materials such as silicon, silicon germanium, germanium or gallium arsenide; the crystal orientation of the first doped semiconductor layer can be amorphous, nanocrystalline, microcrystalline, single crystal or polycrystalline. When the second doped semiconductor layer is formed on a partial area of ​​the backlight surface of the semiconductor substrate, the material and crystal orientation of the second doped semiconductor layer can refer to the material of the first doped semiconductor layer described above, and will not be repeated here. Among them, when the first doped semiconductor layer and the second doped semiconductor layer are both formed on the semiconductor substrate, the materials of the first doped semiconductor layer and the second doped semiconductor layer can be the same or different.

[0069] In some cases, the back-contact cell provided by embodiments of the present invention may also be a cell having a selective passivation contact structure. In this case, a first passivation layer is formed between the first doped semiconductor layer and the semiconductor substrate, and / or a second passivation layer is formed between the second doped semiconductor layer and the semiconductor substrate. The materials of the first and second passivation layers can be determined based on the materials of the first and second doped semiconductor layers, respectively, as well as the type of selective passivation contact structure required in the actual application scenario.

[0070] With respect to the first passivation layer, when the portion of the back-contact cell corresponding to the first doped region has a heterogeneous contact structure, the material of the first passivation layer is intrinsic amorphous silicon and / or intrinsic microcrystalline silicon, and the material of the first doped semiconductor layer is doped amorphous silicon and / or doped microcrystalline silicon. When the portion of the back-contact cell corresponding to the first doped region has a tunneling passivation contact structure, the first passivation layer is a tunneling passivation layer, and the material of the tunneling passivation layer can be silicon oxide, aluminum oxide, titanium oxide, or the like; and the material of the first doped semiconductor layer is doped polycrystalline silicon.

[0071] Similarly, for the second passivation layer, when the portion of the back-contact cell corresponding to the second doped region has a heterogeneous contact structure, the material of the second passivation layer is intrinsic amorphous silicon and / or intrinsic microcrystalline silicon, and the material of the second doped semiconductor layer is doped amorphous silicon and / or doped microcrystalline silicon. When the portion of the back-contact cell corresponding to the second doped region has a tunneling passivation contact structure, the second passivation layer is a tunneling passivation layer, and the material of the second doped semiconductor layer is doped polycrystalline silicon.

[0072] Optionally, the semiconductor substrate included in the semiconductor base is a P-type semiconductor substrate, the first contact region is a P-type doped region formed within the semiconductor substrate by sintering an electrode paste used to manufacture the first electrode, the second doped semiconductor layer is an N-type doped polycrystalline silicon layer, and a tunneling passivation layer is formed between the P-type semiconductor substrate and the N-type doped polycrystalline silicon layer. In this case, the solar cell provided by the embodiment of the present invention is a HPBC (composite passivated back contact) cell. The tunneling passivation layer and the N-type doped polycrystalline silicon layer constitute an N-type tunneling passivation contact structure.

[0073] For the above-mentioned first doping region and second doping region, since the range of the first doping region and the second doping region affect the junction area range of the PN junction in the back contact battery, and thus affect the strength of the built-in electric field in the back contact battery, the area ratio between the first doping region and the second doping region can be determined according to the requirements for the junction area range of the PN junction in the actual application scenario, and no specific limitation is made here.

[0074] For example, Figures 1 to 3 As shown, the area ratio between the first doping region 11 and the second doping region 12 can be greater than or equal to 2:8 and less than or equal to 3:7. For example, the area ratio between the first doping region 11 and the second doping region 12 can be 2:8, 6:19, or 3:7. In this case, if the area ratio between the first doping region 11 and the second doping region 12 is within the above range, it can prevent the corresponding conductive type carriers in the semiconductor substrate from being unable to be timely transmitted to the first electrode 13 through the first doping region 11 due to the small area between the first doping region 11 and the second doping region 12. In addition, it can also prevent the area ratio of the second doping region 12 from being small due to the large area between the first doping region 11 and the second doping region 12. This ensures that the second doping region 12, which serves as the emitter region, has a relatively large area on the backlight side, which is beneficial to increasing the strength of the built-in electric field, further reducing the carrier recombination rate on the backlight side, and thereby improving the photoelectric conversion efficiency of the back-contact cell.

[0075] As for the morphology of the first doping region and the second doping region, since the projections of the first electrode and the second electrode on the semiconductor substrate are respectively located in the first doping region and the second doping region, the morphology of the first doping region and the second doping region can be determined according to the morphology of the first electrode and the second electrode in the actual application scenario, and no specific limitation is made here.

[0076] For example, Figure 4As shown, when the back contact cell provided in the embodiment of the present invention is a main grid-less back contact cell, the first electrode 13 and the second electrode 14 both include a plurality of collector electrodes 16 extending along the first direction and spaced apart along the second direction. The collector electrodes 16 included in the first electrode 13 and the collector electrodes 16 included in the second electrode 14 are spaced apart along the second direction. In this case, the shading area of ​​the first electrode 13 and the second electrode 14 on the backlight side is smaller, which is beneficial for allowing more light to be refracted into the semiconductor substrate through the backlight side of the back contact cell, which is beneficial for improving the photoelectric conversion efficiency of the back contact cell. In addition, the amount of consumables used in the first electrode 13 and the second electrode 14 can also be reduced, which is beneficial for reducing the manufacturing cost of the back contact cell.

[0077] Specifically, the first direction and the second direction can be any two directions parallel to the backlight surface and different from each other. Secondly, the collector electrodes included in the first electrode and the second electrode can be straight-line collector electrodes, wavy-line collector electrodes, or broken-line collector electrodes. In the above case, Figure 1 As shown, the first doping region 11 and the second doping region 12 may be rectangular strip regions, wavy strip regions, etc. located on the backlight side of the semiconductor substrate and matching the morphology of the first electrode 13 and the second electrode 14 respectively.

[0078] For example, Figure 2 and Figure 3 ,as well as Figure 5 and Figure 6As shown, when the back-contact cell provided in an embodiment of the present invention is a busbar back-contact cell, the first electrode 13 and the second electrode 14 both include a plurality of bus electrodes 15 and a plurality of collector electrodes 16. The bus electrodes 15 included in the first electrode 13 and the bus electrodes 15 included in the second electrode 14 both extend along the first direction and are spaced apart along the second direction, which is different from the first direction. The collector electrodes 16 included in the first electrode 13 and the collector electrodes 16 included in the second electrode 14 both extend along the second direction and are spaced apart along the first direction. At least a portion of each collector electrode 16 included in the first electrode 13 penetrates the surface passivation layer and is in ohmic contact with the first doped region 11. At least a portion of each collector electrode 16 included in the second electrode 14 penetrates the surface passivation layer and is in ohmic contact with the second doped region 12. Each bus electrode 15 is connected to a collector electrode 16 of the same polarity as itself and is insulated from a collector electrode 16 of the opposite polarity. In this case, both the first electrode 13 and the second electrode 14 include a collector electrode 16 for collecting carriers, and also include a bus electrode 15 for collecting and conducting carriers collected by at least the collector electrode 16 of the same polarity. Because the bus electrode 15 has a lower resistivity than the collector electrode 16, it helps improve the conductivity of the first electrode 13 and the second electrode 14, reduces transmission losses, and thus helps improve the photoelectric conversion efficiency of the back-contact cell.

[0079] Specifically, the first direction and the second direction can be any two directions that are parallel to the backlight surface and different from each other. Secondly, the collecting electrodes included in the first electrode and the second electrode can be straight-line collecting electrodes, wavy-line collecting electrodes or broken-line collecting electrodes, etc. The bus electrodes included in the first electrode and the second electrode can be straight-line bus electrodes, wavy-line bus electrodes or broken-line bus electrodes, etc. In addition, the collecting electrodes included in the first electrode and the second electrode can both be continuous collecting electrodes, in which case each bus electrode can be insulated from the collecting electrode with the opposite polarity to itself by an insulating material. Or, as Figure 5 As shown, the collector electrodes 16 included in the first electrode 13 and the second electrode 14 are discontinuous collector electrodes, and each discontinuous collector electrode is disconnected at the intersection with the bus electrode 15 of the opposite polarity. Alternatively, as Figure 6 As shown, along the first direction, of all the collecting electrodes 16 included in the first electrode 13 and the second electrode 14, the two collecting electrodes 16 located on the outer sides are the collecting electrodes 16 included in the second electrode 14, and the two collecting electrodes 16 located on the outer sides are continuous collecting electrodes. Of all the collecting electrodes 16 included in the first electrode 13 and the second electrode 14, except for the two collecting electrodes 16 located on the outer sides, the remaining collecting electrodes 16 are discontinuous collecting electrodes, and each discontinuous collecting electrode is disconnected at the intersection with the bus electrode 15 of the opposite polarity.

[0080] It should be noted that a collector electrode included in the first electrode has a polarity opposite to that of a collector electrode included in the second electrode (or a bus electrode included in the second electrode), and has the same polarity as another collector electrode included in the first electrode (or a bus electrode included in the first electrode). Similarly, a bus electrode included in the first electrode has a polarity opposite to that of a collector electrode included in the second electrode (or a bus electrode included in the second electrode), and has the same polarity as another bus electrode included in the first electrode (or a collector electrode included in the first electrode). Accordingly, the situations of electrodes with the same or opposite polarity corresponding to the collector electrode and bus electrode included in the second electrode can be referred to the previous text and will not be repeated here.

[0081] In addition, when the back-contact cell provided in the embodiment of the present invention is a busbar back-contact cell, each collector electrode included in the first electrode may be in ohmic contact with the first doped region over a portion of its length, in which case the contact between each collector electrode included in the first electrode and the first doped region is a localized contact; or each collector electrode included in the first electrode may be in ohmic contact with the first doped region over all portions of its length, in which case the contact between each collector electrode included in the first electrode and the first doped region is a full-area contact. Furthermore, the bus electrode included in the first electrode may be isolated from the first doped region by a surface passivation layer, or at least a portion of the bus electrode included in the first electrode may also be in ohmic contact with the first doped region. As for the second electrode, each collector electrode included in the second electrode may be in ohmic contact with the second doped region over a portion of its length, or each collector electrode included in the second electrode may be in ohmic contact with the second doped region over all portions of its length. Furthermore, the bus electrode included in the second electrode may be isolated from the second doped region by a surface passivation layer, or at least a portion of the bus electrode included in the second electrode may also be in ohmic contact with the second doped region.

[0082] For example, when the collector electrodes included in the first electrode and the second electrode are both continuous collector electrodes, the bus electrodes included in the first electrode and the second electrode may not be in ohmic contact with the first doped region or the second doped region, respectively. For another example, when at least part of the collector electrodes included in the first electrode and the second electrode are discontinuous collector electrodes, the bus electrodes included in the first electrode and the second electrode may not be in ohmic contact with the first doped region or the second doped region, respectively, or may at least partially be in ohmic contact with the first doped region or the second doped region, respectively.

[0083] In the above case, when the first electrode and the second electrode include collector electrodes that are continuous collector electrodes, as Figure 1As shown, the first doped region 11 and the second doped region 12 can be rectangular strip regions, wavy strip regions, etc. located on the backlight side of the semiconductor substrate and matching the morphology of the first electrode 13 and the second electrode 14 respectively. When at least part of the collector electrodes included in the first electrode 13 and the second electrode 14 are discontinuous collector electrodes, as shown in FIG. Figure 2 and Figure 3 As shown, the first doping region 11 and the second doping region 12 can be interdigitated regions located on the backlight side of the semiconductor substrate and matching the morphology of the first electrode 13 and the second electrode 14 respectively. Figure 6 As shown, along the first direction, among all the collecting electrodes 16 included in the first electrode 13 and the second electrode 14, the two collecting electrodes 16 located on the outside are the collecting electrodes 16 included in the second electrode 14, and the two collecting electrodes 16 located on the outside are continuous collecting electrodes; at the same time, among all the collecting electrodes 16 included in the first electrode 13 and the second electrode 14, the remaining collecting electrodes 16 except the two collecting electrodes 16 located on the outside are discontinuous collecting electrodes, as shown in FIG. Figure 3 As shown, the second doping regions 12 located on different areas on the backlight side of the semiconductor substrate are connected to each other. At this time, the second doping region 12 surrounds at least one first doping region 11, which is beneficial to increasing the area ratio of the second doping region 12 serving as the emitter region on the backlight side, which is beneficial to improving the strength of the built-in electric field, reducing the carrier recombination rate on the backlight side, and further improving the photoelectric conversion efficiency of the back-contact battery.

[0084] As for the specific specifications of the first and second doped regions, the specifications of the first doped region can be determined based on the specifications of the first electrode to be manufactured. Secondly, because the second doped region and the first doped region are located on the backlight side, the specifications of the second doped region can also be determined once the specific specifications of the first doped region are determined.

[0085] For example, Figure 2 、 Figure 3 and Figure 8As shown, along the first direction, the width W of the portion of the first doped region 11 corresponding to the portion below each collector electrode included in the first electrode can be greater than or equal to 190 μm and less than 260 μm. For example, along the first direction, the width W of the portion of the first doped region 11 corresponding to the portion below each collector electrode included in the first electrode can be 190 μm, 200 μm, 220 μm, 240 μm, or 260 μm. In this case, because each collector electrode included in the first electrode has a certain width, and the equipment used to manufacture the first electrode has a certain processing error, the width W of the portion of the first doped region 11 corresponding to the portion below each collector electrode included in the first electrode along the first direction is within the above range. This can prevent the collector electrode included in the first electrode from overlapping with the second doped region 12 of opposite polarity due to the smaller width W of the portion of the first doped region 11 corresponding to the portion below each collector electrode included in the first electrode, thereby ensuring that the back-contact battery has high electrical reliability. In addition, it can also prevent the area of ​​the second doping region 12 located on the backlight side together with the first doping region 11 from being small due to the large width W of the portion below each collecting electrode included in the first electrode corresponding to the first doping region 11, thereby ensuring that the second doping region 12 serving as the emitter region has a relatively large area on the backlight side, which is beneficial to increasing the intensity of the built-in electric field, reducing the carrier recombination rate on the backlight side, and further improving the photoelectric conversion efficiency of the back-contact battery.

[0086] In addition, when the back-contact battery provided in the embodiment of the present invention is a main-grid back-contact battery, the width of the portion of the first doped region located below the bus electrode included in the first electrode can be determined based on the width of the bus electrode included in the first electrode and the processing error of the equipment for manufacturing the first electrode, and is not specifically limited here.

[0087] The material and thickness of the surface passivation layer can be determined based on actual needs, as long as it can be applied to the back-contact battery provided by the embodiments of the present invention. For example, the material of the surface passivation layer can include at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, and silicon carbide.

[0088] For the above-mentioned first electrode and second electrode, after the first electrode and second electrode penetrate the surface passivation layer and respectively make ohmic contact with the first doping region and the second doping region, the actual formation area of ​​the surface passivation layer on the backlight side becomes smaller, thereby affecting the passivation effect of the surface passivation layer on the backlight side. The larger the area of ​​the first electrode and / or the second electrode penetrating the surface passivation layer, the greater the distribution density of the first electrode and / or the second electrode, thereby making the series resistance of the back contact battery smaller. In addition, the ratio of the first electrode and the second electrode penetrating the surface passivation layer and respectively making ohmic contact with the first doping region and the second doping region will also affect the transmission loss of carriers transmitted to the adjacent collector electrode. In the above case, the specific area ratio of the first electrode and the second electrode penetrating the surface passivation layer and respectively making ohmic contact with the first doping region or the second doping region can be determined based on the requirements for the passivation effect of the surface passivation layer, the specific structure of the first electrode and the second electrode, the series resistance of the solar cell, and the transmission loss in the actual application scenario.

[0089] Specifically, for the first electrode, the portion of the first doped region that is in ohmic contact with the first electrode is the first contact region. The area ratio of the first contact region to the emitter region can be any value greater than or equal to 0.93% and less than or equal to 4.42%. For example, the area ratio of the first contact region to the emitter region can be 0.93%, 1.00%, 1.50%, 2.00%, 2.50%, 3.00%, 3.50%, 4.00%, or 4.42%.

[0090] The area ratio of the first contact region to the first doped region may be any value greater than or equal to 2.16% and less than or equal to 17.7%. For example, the area ratio of the first contact region to the first doped region may be 2.16%, 3%, 5%, 8%, 10%, 12%, 15%, 16%, or 17.7%.

[0091] It should be noted that when the back-contact cell provided by the embodiment of the present invention is a busbar-less back-contact cell, the portion of the first doped region exposed through the first conductive window is in ohmic contact with all the collector electrodes included in the first electrode. When the back-contact cell provided by the embodiment of the present invention is a busbar-equipped back-contact cell, the portion of the first doped region exposed through the first conductive window may be in ohmic contact only with all the collector electrodes included in the first electrode, but not with the bus electrodes included in the first electrode; or the portion of the first doped region exposed through the first conductive window may be in ohmic contact not only with all the collector electrodes included in the first electrode, but also with all the bus electrodes included in the first electrode.

[0092] In addition, embodiments of the present invention define the portion of the first doped region exposed through the first conductive window that makes ohmic contact with each collector electrode included in the first electrode as a second contact region. Furthermore, the portion of the second doped region exposed through the second conductive window that makes ohmic contact with each collector electrode included in the second electrode is defined as a third contact region. The area ratio of the second contact region to the first doped region may be different from the area ratio of the third contact region to the second doped region. In this case, in actual applications, the doping concentrations of the first and second doped regions differ, resulting in different carrier transfer resistances in the two regions, which can lead to current mismatch. This application addresses the current mismatch by balancing the carrier collection capabilities of the first and second doped regions by varying the area proportions of the corresponding contact regions within the doped regions. Based on this, the area ratios of the second contact region to the first doped region, as well as the area ratios of the third contact region to the second doped region, can be set based on the area proportions of the first and second doped regions on the backlight side, respectively, to ensure that the transmission loss of the corresponding carriers to the collector electrodes included in the adjacent first electrode and the transmission loss of the corresponding carriers to the collector electrodes included in the adjacent second electrode are both low. In addition, since the materials and widths of collector electrodes with different polarities can be set differently, the proportion of the second contact area in the first doping area and the proportion of the third contact area in the second doping area are set to different values, that is, the contact ratios of collector electrodes with different widths and corresponding doping areas are set to different proportions, ensuring that collector electrodes with opposite polarities and different widths have higher carrier collection capabilities, and that the carriers collected by the first doping area and the second doping area are adapted.

[0093] It should be noted that the area ratio of the second contact region to the first doped region may also be equal to the area ratio of the third contact region to the first doped region. Secondly, when the area ratio of the second contact region to the first doped region is different from the area ratio of the third contact region to the second doped region, the difference between the two can be set based on the area ratio of the first doped region to the second doped region in the actual application scenario, the difference in the width of the collector electrodes included in the first electrode and the second electrode, and actual needs, and is not specifically limited here.

[0094] Exemplarily, the area ratio of the second contact region to the first doped region may be greater than or equal to 2.16% and less than or equal to 17.7%. For example, the area ratio of the second contact region to the first doped region may be 2.16%, 3%, 5%, 8%, 10%, 12%, 15%, 16%, or 17.7%. In this case, the area ratio of the second contact region to the first doped region is equal to the area ratio of the first contact region to the first doped region; in this case, only the collector electrode of the first electrode is electrically connected to the first doped region, and the bus electrode included in the first electrode is not in direct electrical contact with the first doped region.

[0095] Exemplarily, when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, the area ratio of the third contact region to the second doping region can be greater than or equal to 0.78% and less than or equal to 13.15%, or, when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the area ratio of the third contact region to the second doping region can be greater than or equal to 0.78% and less than or equal to 17.38%. Similar to the area ratio of the first contact region to the first doping region, when the spacing between adjacent second electrodes increases, the carrier transmission distance of the corresponding conductivity type will also increase. The present application overcomes the problem of increased power loss due to the increase in the carrier transmission distance by increasing the area of ​​the third contact region to the second doping region. On the other hand, the area of ​​the third contact region will also affect the area of ​​the first doping region. Compared with double-sided contact cells, the first doped region and the second doped region of the back contact cell are located on the same surface. The area of ​​the third contact region occupied by the second doped region becomes larger, and the area of ​​the first doped region, i.e., the field region, may become smaller, affecting the further separation of carriers. The present application solves the problem of carrier transport while also satisfying the further separation of carriers by designing the area ratio of the third contact region to the second doped region, thereby increasing the probability of carrier collection. In addition, the area of ​​the third contact region also affects the passivation effect. The surface passivation layer is used to chemically passivate the backlight side of the semiconductor substrate to reduce the carrier recombination rate on the backlight side. Within a certain range, the passivation effect of the surface passivation layer on the backlight side is proportional to the actual area of ​​the surface passivation layer formed on the backlight side of the semiconductor substrate. In addition, the first electrode formed on the backlight side needs to penetrate the surface passivation layer through the first conductive window to make ohmic contact with the first doped region, and the second electrode needs to penetrate the surface passivation layer through the second conductive window to make ohmic contact with the second doped region, and the area of ​​the second doped region exposed to the outside through the second conductive window is the third contact region. In this case, after forming the first and second electrodes, the actual surface passivation layer area on the backlight side needs to be reduced by the area of ​​the first and second conductive windows penetrating the surface passivation layer. Based on this, it can be understood that the larger the area of ​​the second electrode penetrating the surface passivation layer, the worse the passivation effect of the surface passivation layer on the backlight side. Furthermore, the larger the area of ​​the second electrode penetrating the surface passivation layer, the greater the distribution density of the second electrodes, resulting in a lower series resistance of the back-contact battery.In the above case, under the premise that other factors remain unchanged, when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, the area ratio of the third contact region to the second doping region can be greater than or equal to 0.78% and less than or equal to 13.15%, or when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the area ratio of the third contact region to the second doping region can be greater than or equal to 0.78% and less than or equal to 17.38%. When the area ratio of the third contact region to the second doping region is reasonably set, the carriers are further separated, the carrier transmission, the surface passivation effect, and the series resistance are optimized, thereby helping to improve the photoelectric conversion efficiency of the back contact battery. In this case, the area ratio of the third contact region to the second doping region is within the above range, which can prevent the transmission loss from being large due to the small ratio, and can also prevent the metal composite loss from being high and the surface passivation effect from being small due to the large ratio, which can further improve the balance between the surface passivation effect, the series resistance and the transmission loss, and further improve the photoelectric conversion efficiency of the back contact battery. In addition, the third contact region is the region where the collector electrode included in the second electrode contacts the second doped region. When the conductivity type of the second doped region is N-type, the second electrode is a negative electrode. When the conductivity type of the second electrode is P-type, the second electrode is a positive electrode. Based on this, it can be seen from the above two area ratios that when the second electrode is a positive electrode, the upper limit of the area ratio of the third contact region to the second doped region is relatively large. In this case, aluminum material can be used to manufacture the collector electrode included in the second electrode to reduce the consumption of metal slurry, which is beneficial to controlling the manufacturing cost of the back-contact battery.

[0096] For example: when the conductivity type of the first doping region is P type and the conductivity type of the second doping region is N type, the area ratio of the third contact region to the second doping region can be 0.78%, 1%, 3%, 5%, 8%, 10%, 12% or 13.15%.

[0097] For another example, when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the area ratio of the third contact region to the second doping region can be 0.78%, 2%, 5%, 8%, 10%, 12%, 15%, 16% or 17.38%, etc.

[0098] For example, Figure 9 As shown, when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, the area ratio between the second contact region and the third contact region can be greater than or equal to 33.6% and less than or equal to 120%. Or, as Figure 10As shown, when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the area ratio between the second contact region and the third contact region can be greater than or equal to 25.43% and less than or equal to 120%. In this case, when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, the first electrode is a positive electrode and the second electrode is a negative electrode; at this time, the area ratio between the second contact region and the third contact region is within the above range, which can prevent the holes in the semiconductor substrate of the back contact battery from being collected and extracted in time by the first electrode when the back contact battery is in the working state due to the small ohmic contact area between the collector electrode included in the positive electrode and the first doping region, which is beneficial to reducing the carrier recombination rate on the backlight side and further improving the photoelectric conversion efficiency of the back contact battery; in addition, the area ratio between the second contact region and the third contact region has a large optional range, which is beneficial to improving the applicability of the back contact battery provided by the embodiment of the utility model in different application scenarios. As for the beneficial effect of the area ratio between the second contact region and the third contact region being greater than or equal to 25.43% and less than or equal to 120% when the conductivity type of the first doped region is N-type and the conductivity type of the second doped region is P-type, you can refer to the beneficial effect analysis of the area ratio between the second contact region and the third contact region being greater than or equal to 33.6% and less than or equal to 120% when the conductivity type of the first doped region is P-type and the conductivity type of the second doped region is N-type, which will not be repeated here.

[0099] For example, when the conductivity type of the first doped region is P-type and the conductivity type of the second doped region is N-type, the area ratio between the second contact region and the third contact region may be 33.6%, 40.0%, 60.0%, 80.0%, 100.0% or 120%, etc.

[0100] For example: when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the area ratio between the second contact region and the third contact region can be 25.43%, 26.0%, 30.0%, 50.0%, 70.0%, 90.0%, 110.0% or 120%, etc.

[0101] In the above case, in the first electrode, the ratio of the area of ​​the second contact region corresponding to each collecting electrode to its own cross-sectional area can be determined based on the passivation effect of the surface passivation layer in the actual application scenario, and the contact performance requirements between the first electrode and the semiconductor substrate. In addition, the widths of the collecting electrodes with different polarities may be different (such as the collecting electrodes included in the negative electrode are usually made of silver material and have a smaller width; while the collecting electrodes included in the positive electrode are usually made of aluminum material and have a larger width. Of course, the widths of the collecting electrodes with different polarities may also be the same), and the contact ratios of the collecting electrodes with different widths to the corresponding doping regions may be different. Therefore, according to the different conductivity types of the first doping regions, the ratio of the area of ​​the second contact region corresponding to each collecting electrode included in the first electrode to its own cross-sectional area is divided into the following two cases for explanation:

[0102] For example, when the conductivity type of the first doping region is P type and the conductivity type of the second doping region is N type, Figure 11 As shown, the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area can be greater than or equal to 5% and less than or equal to 22.5%. For example, when the conductivity type of the first doped region is P-type and the conductivity type of the second doped region is N-type, the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area can be 5%, 8%, 10%, 15%, 20%, or 22.5%. In this case, when the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area is within the above range, it can prevent the ohmic contact area between each collector electrode included in the first electrode and the first doped region from being small, resulting in a large contact resistance between the first electrode and the semiconductor substrate, thereby improving the contact performance between the first electrode and the semiconductor substrate. In addition, it can also prevent the actual formed area of ​​the surface passivation layer on the backlight side from being small due to the large surface area of ​​each collector electrode included in the first electrode penetrating the surface passivation layer due to the large ratio, thereby ensuring that the surface passivation layer has a relatively high surface passivation effect on the backlight side.

[0103] For example, when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, Figure 12As shown, the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area can be greater than or equal to 12% and less than or equal to 72%. For example: when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area can be 12%, 20%, 40%, 60% or 72%, etc. The beneficial effects in this case can refer to the beneficial effect analysis of the ratio of the area of ​​the second contact region corresponding to each collector electrode included in the first electrode to its own cross-sectional area being greater than or equal to 5% and less than or equal to 22.5% when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, which will not be repeated here.

[0104] In actual application, as mentioned above, when the back-contact battery provided in the embodiment of the present invention is a main-grid back-contact battery, the bus electrode included in the first electrode may be in ohmic contact with the first doped region. In this case, the portion of the first doped region that is exposed to the outside through the first conductive window and is in ohmic contact with each bus electrode included in the first electrode is defined as the fourth contact region. It can be understood that the above-mentioned first contact region is equal to the sum of the areas of all second contact regions and all fourth contacts. Based on this, the size of the above-mentioned fourth contact can be determined according to the specifications of the first contact region, the second contact region, the bus electrode included in the first electrode, and the conductivity type of the first doped region mentioned above, and is not specifically limited here.

[0105] For example, Figure 13 As shown, the ratio of the area of ​​the fourth contact region corresponding to each bus electrode included in the first electrode to its own cross-sectional area can be greater than or equal to 0.67% and less than or equal to 100%. For example, the ratio of the area of ​​the fourth contact region corresponding to each bus electrode included in the first electrode to its own cross-sectional area can be 0.67%, 10%, 30%, 50%, 80% or 100%, etc. In this case, in addition to each collector electrode included in the first electrode being able to penetrate the surface passivation layer and make ohmic contact with the first doped region, the bus electrode included in the first electrode can also penetrate the surface passivation layer and make ohmic contact with the first doped region, providing another possible solution for the contact method between the first electrode and the first doped region, which is conducive to expanding the scope of application of the back contact battery provided by the embodiment of the present invention. In addition, the optional range of the ratio of the area of ​​the fourth contact region corresponding to each bus electrode included in the first electrode to its own cross-sectional area is large, and the appropriate value can be determined according to the actual application scenario, which is conducive to expanding the applicability of the back contact battery provided by the embodiment of the present invention in different application scenarios.

[0106] For example, Figure 14As shown, when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, the area ratio between the fourth contact region and the second contact region can be greater than or equal to 1.23% and less than or equal to 5.05%. For example, when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, the area ratio between the fourth contact region and the second contact region can be 1.23%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5% or 5.05%, etc. In this case, the area of ​​the collector electrode included in the first electrode in ohmic contact with the first doping region accounts for the vast majority of the total area exposed to the outside of the first doping region through the first conductive window. Based on this, since the cross-sectional area of ​​the collecting electrode is usually smaller than the cross-sectional area of ​​the bus electrode, when the area ratio between the fourth contact region and the second contact region is greater than or equal to 1.23% and less than or equal to 5.05%, the area of ​​ohmic contact between the bus electrode included in the first electrode and the first doping region is smaller, which is beneficial to reducing the number of bus electrodes included in the first electrode, thereby reducing the shading area of ​​the bus electrode included in the first electrode, and further beneficial to allowing more light to pass through the backlight surface of the back contact battery and be utilized by the semiconductor substrate, thereby improving the photoelectric conversion efficiency of the back contact battery.

[0107] For example, Figure 15 As shown, when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the area ratio between the fourth contact region and the second contact region can be greater than or equal to 1.23% and less than or equal to 6.17%. For example, when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the area ratio between the fourth contact region and the second contact region can be 1.23%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5% or 6.17%, etc. The beneficial effects in this case can refer to the beneficial effects of the area ratio between the fourth contact region and the second contact region being greater than or equal to 1.23% and less than or equal to 5.05% when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, and will not be repeated here.

[0108] As for the first electrode, the specific width of the second contact region corresponding to each collecting electrode, and the width ratio between each second contact region and the first doped region located below each collecting electrode included in the first electrode can be determined based on the passivation effect of the surface passivation layer in the actual application scenario, and the contact performance requirements between the first electrode and the semiconductor substrate.

[0109] For example, Figure 16As shown, along the first direction, the width of each second contact area can be greater than or equal to 28μm and less than or equal to 120μm. For example: along the first direction, the width of each second contact area can be 28μm, 30μm, 60μm, 80μm, 100μm or 120μm, etc. In this case, along the first direction, the width of each second contact area is within the above range, which can prevent the contact resistance between each collector electrode included in the first electrode and the semiconductor substrate from being large due to the smaller area of ​​the second contact area caused by the smaller width, which is beneficial to improving the transmission performance of the first electrode and reducing transmission loss. In addition, it can also prevent the area of ​​each collector electrode included in the first electrode from penetrating the surface passivation layer from being large due to the larger width, ensuring that the surface passivation layer has a higher passivation effect on the backlight side.

[0110] Exemplarily, along the first direction, the width of each second contact region is the first width, and the width of the portion of the first doped region located below each collector electrode included in the first electrode is the second width. The ratio of the second width to the first width may be greater than or equal to 475% and less than or equal to 650%. For example, the ratio of the second width to the first width may be 475%, 500%, 520%, 550%, 580%, 600%, 620%, or 650%. In this case, when the ratio of the second width to the first width is small, the second width may be smaller or the first width may be larger; and when the ratio of the second width to the first width is large, the second width may be larger or the first width may be smaller. Based on this, the ratio of the second width to the first width is within the above range, which can prevent the second width from being smaller and / or the first width from being larger due to the smaller ratio of the second width to the first width, and can also prevent the second width from being larger and / or the first width from being smaller due to the larger ratio of the second width to the first width. The effects of preventing the first width from being larger and smaller, and preventing the second width from being larger and smaller can be referred to the previous text and will not be repeated here.

[0111] For the second electrode, the ratio of each collector electrode included in the second electrode to the ohmic contact with the second doped region, and when the back contact battery is a main grid back contact battery, the ratio of the bus electrode included in the second electrode to the ohmic contact with the second doped region can be determined according to the actual application scenario, as long as it can be applied to the back contact battery provided in the embodiment of the present invention.

[0112] In a second aspect, an embodiment of the present invention further provides a photovoltaic module, which includes a back-contact cell array formed by back-contact cells provided by the first aspect and various implementations thereof through conductive interconnects.

[0113] The beneficial effects of the second aspect and its various implementations in the embodiments of the present invention can be analyzed with reference to the beneficial effects of the first aspect and its various implementations, and will not be repeated here.

[0114] While the above description does not provide detailed technical details regarding the patterning and etching of each layer, those skilled in the art will appreciate that various technical means can be employed to form layers, regions, and the like in desired shapes. Furthermore, those skilled in the art may devise methods that differ from those described above to form the same structure. Furthermore, while each embodiment has been described separately, this does not mean that the measures in each embodiment cannot be advantageously combined.

[0115] The above describes the embodiments of the present disclosure. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make various substitutions and modifications, which are intended to fall within the scope of the present disclosure.

Claims

1. A back contact battery, characterized in that: include: A semiconductor substrate, wherein a backlight surface of the semiconductor substrate has a first doping region and a second doping region of opposite conductivity types, and the second doping region is an emitter region; The first doping regions and at least a portion of the second doping regions are alternately distributed; a surface passivation layer formed on the first doped region and the second doped region on the backlight side of the semiconductor substrate; a first conductive window and a second conductive window penetrating the surface passivation layer; A first electrode and a second electrode are formed on a backlight side of the semiconductor substrate, and the first electrode and the second electrode are insulated from each other; a projection of the first electrode on the semiconductor substrate is located within the first doped region, and the first electrode penetrates the surface passivation layer through the first conductive window and is in ohmic contact with the first doped region; The projection of the second electrode on the semiconductor substrate is located in the second doped region, and the second electrode penetrates the surface passivation layer through a second conductive window and is in ohmic contact with the second doped region; Among them, the area of ​​the first doped region exposed to the outside through the first conductive window is the first contact region; the area ratio of the first contact region to the emitter region is greater than or equal to 0.93% and less than or equal to 4.42%; the area ratio of the first contact region to the first doped region is greater than or equal to 2.16% and less than or equal to 17.7%.

2. The back contact battery according to claim 1, characterized in that The first electrode and the second electrode each include a plurality of bus electrodes and a plurality of collecting electrodes; the bus electrodes included in the first electrode and the bus electrodes included in the second electrode both extend along a first direction and are spaced apart along a second direction, and the second direction is different from the first direction; the collecting electrodes included in the first electrode and the collecting electrodes included in the second electrode both extend along the second direction and are spaced apart along the first direction; at least a portion of each collecting electrode included in the first electrode penetrates the surface passivation layer and is in ohmic contact with the first doped region; at least a portion of each collecting electrode included in the second electrode penetrates the surface passivation layer and is in ohmic contact with the second doped region; each bus electrode is connected to a collecting electrode with the same polarity as itself and is insulated from a collecting electrode with an opposite polarity.

3. The back contact battery according to claim 2, characterized in that The portion of the first doped region exposed through the first conductive window that is in ohmic contact with each collector electrode included in the first electrode is a second contact region; the portion of the second doped region exposed through the second conductive window that is in ohmic contact with each collector electrode included in the second electrode is a third contact region; The area ratio of the second contact region to the first doping region is different from the area ratio of the third contact region to the second doping region.

4. The back contact battery according to claim 3, characterized in that An area ratio of the second contact region to the first doping region is greater than or equal to 2.16% and less than or equal to 17.7%; and / or, when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, an area ratio of the third contact region to the second doping region is greater than or equal to 0.78% and less than or equal to 13.15%; or, when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, an area ratio of the third contact region to the second doping region is greater than or equal to 0.78% and less than or equal to 17.38%; And / or, when the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, the area ratio between the second contact region and the third contact region is greater than or equal to 33.6% and less than or equal to 120%, or, when the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the area ratio between the second contact region and the third contact region is greater than or equal to 25.43% and less than or equal to 120%.

5. The back contact battery according to claim 3, characterized in that When the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, a ratio of an area of ​​the second contact region corresponding to each collector electrode of the first electrode to its own cross-sectional area is greater than or equal to 5% and less than or equal to 22.5%; or, When the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, the ratio of the area of ​​the second contact region corresponding to each collecting electrode included in the first electrode to its own cross-sectional area is greater than or equal to 12% and less than or equal to 72%.

6. The back contact battery according to claim 3, characterized in that In a case where at least a portion of the bus electrode included in the first electrode penetrates the surface passivation layer and is in ohmic contact with the first doped region, a portion of the first doped region exposed through the first conductive window and in ohmic contact with each bus electrode included in the first electrode is a fourth contact region; The ratio of the area of ​​the fourth contact region corresponding to each bus electrode included in the first electrode to the cross-sectional area of ​​the fourth contact region is greater than or equal to 0.67% and less than or equal to 100%.

7. The back contact battery according to claim 6, characterized in that When the conductivity type of the first doping region is P-type and the conductivity type of the second doping region is N-type, an area ratio between the fourth contact region and the second contact region is greater than or equal to 1.23% and less than or equal to 5.05%; or, When the conductivity type of the first doping region is N-type and the conductivity type of the second doping region is P-type, an area ratio between the fourth contact region and the second contact region is greater than or equal to 1.23% and less than or equal to 6.17%.

8. The back contact battery according to claim 3, characterized in that Along the first direction, the width of each of the second contact regions is greater than or equal to 28 μm and less than or equal to 120 μm; and / or, Along the first direction, the width of the first doped region corresponding to the portion below each collector electrode included in the first electrode is greater than or equal to 190 μm and less than 260 μm; and / or, Along the first direction, the width of each second contact region is the first width, the width of the first doped region located below each collector electrode included in the first electrode is the second width, and the ratio of the second width to the first width is greater than or equal to 475% and less than or equal to 650%.

9. The back contact battery according to claim 2, characterized in that Along the first direction, among all the collecting electrodes included in the first electrode and the second electrode, the two collecting electrodes located on the outside are the collecting electrodes included in the second electrode, and the two collecting electrodes located on the outside are continuous collecting electrodes; among all the collecting electrodes included in the first electrode and the second electrode, except the two collecting electrodes located on the outside, the remaining collecting electrodes are discontinuous collecting electrodes, and each of the discontinuous collecting electrodes is disconnected at the intersection with the bus electrode with opposite polarity.

10. The back contact battery according to claim 2, characterized in that The width of the collector electrode included in the first electrode is different from the width of the collector electrode included in the second electrode.

11. The back contact battery according to any one of claims 1 to 10, characterized in that: An area ratio between the first doping region and the second doping region is greater than or equal to 2:8 and less than or equal to 3:

7.

12. A photovoltaic module, characterized in that: The photovoltaic module comprises a back contact cell array formed by the back contact cells according to any one of claims 1 to 11 through conductive interconnectors.

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