Back contact cell and method for manufacturing the same, photovoltaic module

Abstract

The application relates to the photovoltaic field, and provides a back contact cell, a preparation method of the back contact cell, a laminated cell and a photovoltaic module, and at least the performance of the back contact cell can be improved. The back contact cell comprises a substrate, a first doped part, a second doped part, a passivation layer, a first electrode and a second electrode. The substrate has a first area and a second area and a third area between the first area and the second area; the first doped part is located in the first area and the third area; the second doped part is located in the second area and the third area, and the second doped part is located on the same side of the substrate as the first doped part; the passivation layer is located in the second area and the third area, the passivation layer comprises an interface passivation part and a third doped part, the interface passivation part is located between the substrate and the second doped part and between the second doped part and the first doped part, the third doped part is located between the interface passivation part and the second doped part and is spaced from the first doped part, and the doped elements in the third doped part and the doped elements in the second doped part have the same conductive type.

Description

Cross-references to related applications

[0001] This application is a divisional application of Chinese patent application No. 202610290465.8, filed on March 11, 2026, entitled "Back Contact Battery and Preparation Method Thereof, Tandem Battery, Photovoltaic Module". Technical Field

[0002] This application relates to the photovoltaic field, and in particular to a back contact battery and its preparation method, a tandem battery, and a photovoltaic module. Background Technology

[0003] As fossil fuels are gradually depleted, solar energy is becoming increasingly widely used as a new energy alternative. A solar cell is a device that converts sunlight into electrical energy. Solar cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thus facilitating the efficient use of electrical energy.

[0004] Back-contact solar cells are a type of solar cell where all the grid lines are located on the back of the cell. Because there are no metal grid electrodes obstructing the front of the cell, back-contact cells have increased light absorption efficiency, significantly improving short-circuit current and effectively increasing conversion efficiency, making them a promising technology. However, further improving the performance of back-contact solar cells is a pressing issue that needs to be addressed. Summary of the Invention

[0005] This application provides a back contact battery and its preparation method, a tandem battery, and a photovoltaic module, which can at least improve the performance of the back contact battery.

[0006] This application provides a back contact battery. The back contact battery includes: a substrate having a first region and a second region, and a third region located between the first region and the second region; a first doped portion located between the first region and the third region; a second doped portion located between the second region and the third region, and the second doped portion and the first doped portion being located on the same side of the substrate; a passivation layer located between the second region and the third region, the passivation layer including an interface passivation portion and a third doped portion, the interface passivation portion being located between the substrate and the second doped portion, and between the second doped portion and the first doped portion, the third doped portion being located between the interface passivation portion and the second doped portion and spaced apart from the first doped portion, and the doping element in the third doped portion having the same conductivity type as the doping element in the second doped portion; a first electrode electrically connected to the first doped portion; and a second electrode electrically connected to the second doped portion.

[0007] Optionally, the interface passivation portion includes a first sub-portion and a second sub-portion located on both sides of the first sub-portion, wherein the first sub-portion is located between the third doped portion and the substrate; and wherein the thickness of the first sub-portion is less than the thickness of the second sub-portion.

[0008] Optionally, the thickness of the first sub-part is 1nm to 4nm; the thickness of the second sub-part is 7nm to 20nm.

[0009] Optionally, the second doped portion includes: a first doped sub-portion located on the surface of the third doped portion away from the substrate; and a second doped sub-portion adjacent to the first doped sub-portion; wherein the crystallinity of the first doped sub-portion is greater than that of the second doped sub-portion, and / or the grain size of the first doped sub-portion is greater than that of the second doped sub-portion.

[0010] Optionally, the crystallinity of the first doped sub-part is 20% to 80%; the crystallinity of the second doped sub-part is 0% to 10%.

[0011] Optionally, the grain size of the first doped sub-part is 3nm to 200nm; the grain size of the second doped sub-part is less than or equal to 1nm.

[0012] Optionally, the second doped portion includes: a first doped sub-portion located on the surface of the third doped portion away from the substrate; and a second doped sub-portion adjacent to the first doped sub-portion; wherein the doping concentration of the doping element in the first doped sub-portion is greater than the doping concentration of the doping element in the second doped sub-portion.

[0013] Optionally, the thickness of the interface passivation portion located between the third doped portion and the substrate is a first thickness, and the ratio of the thickness of the third doped portion to the first thickness is 1 to 15.

[0014] Optionally, the thickness of the third doped portion is 4nm to 15nm; the thickness of the interface passivation portion located between the third doped portion and the substrate is a first thickness, which is 1nm to 4nm.

[0015] Optionally, the doping concentration of the dopant element in the third doped portion is 5E17 atoms / cm³. 3 ~5E19atoms / cm 3 .

[0016] Optionally, along the first direction, the ratio of the length of the third doped portion to the length of the second doped portion is 0.06 to 0.7.

[0017] This application also provides a method for fabricating a back contact battery. The method includes: providing an initial battery, the initial battery comprising: a substrate having a first region and a second region, and a third region located between the first region and the second region; a first doped portion located between the first region and the third region; an initial doped portion located between the second region and the third region, and the initial doped portion and the first doped portion being located on the same side of the substrate; an initial passivation layer located between the second region and the third region, and located between the substrate and the initial doped portion, and between the initial doped portion and the first doped portion; performing a doping process to transform the initial doped portion into a second doped portion, and transforming a portion of the initial passivation layer spaced apart from the first doped portion into a third doped portion, the remaining portion of the initial passivation layer being an interface passivation portion; wherein the doping element in the third doped portion has the same conductivity type as the doping element in the second doped portion; forming a first electrode and a second electrode, the first electrode being electrically connected to the first doped portion, and the second electrode being electrically connected to the second doped portion.

[0018] Optionally, the doping process includes laser processing.

[0019] Optionally, the wavelength of the laser treatment is 325nm~532nm, and the energy density of the laser treatment is 150mJ / cm². 2 ~5000mJ / cm 2 .

[0020] Optionally, the doping process includes ion implantation.

[0021] Optionally, the energy of the ion implantation treatment is 0.1 keV to 10 keV; the implantation dose of the ion implantation treatment is 1 E11 ions / cm. 2 ~1E17ions / cm 2 The ion implantation process temperature is 25℃~200℃.

[0022] This application also provides a stacked battery. The stacked battery includes: a bottom battery, which is a back contact battery as described above, or a back contact battery prepared by a method described above for preparing a back contact battery; and a perovskite battery located on one side of the bottom battery.

[0023] This application also provides a photovoltaic module. The photovoltaic module includes: a battery string, which is formed by connecting a plurality of back-contact batteries as described above, or by connecting back-contact batteries prepared by the method described above, or by connecting a plurality of stacked batteries as described above; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film opposite to the surface of the battery string.

[0024] The technical solution provided in this application has at least the following advantages: In the back contact battery provided in this application, the passivation layer includes an interface passivation portion and a third doped portion. The interface passivation portion located between the first doped portion and the second doped portion can reduce the leakage current between the first doped portion and the second doped portion, thereby improving the performance of the back contact battery. The interface passivation portion located between the second doped portion and the substrate can passivate the substrate, which also helps to improve the performance of the back contact battery. In addition, the third doped portion is located between the interface passivation portion and the second doped portion, and the doping element in the third doped portion has the same conductivity type as the doping element in the second doped portion. Since the second electrode is electrically connected to the second doped portion, the third doped portion can improve the efficiency of the second electrode in collecting charge carriers, which also helps to improve the performance of the back contact battery. Attached Figure Description

[0025] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a back contact battery provided in an embodiment of this application; Figure 2 This is a schematic diagram of another structure of the back contact battery provided in an embodiment of this application; Figure 3 This is another structural schematic diagram of a back contact battery provided in an embodiment of this application; Figure 4 A schematic diagram of the structure of an initial battery provided in the method for preparing a back contact battery according to an embodiment of this application; Figure 5 This is a schematic diagram of a stacked battery provided in an embodiment of this application; Figure 6This is a schematic diagram of another structure of the stacked battery provided in an embodiment of this application; Figure 7 This is a partial three-dimensional schematic diagram of a cell string in a photovoltaic module provided in an embodiment of this application; Figure 8 This is a partial cross-sectional schematic diagram of a photovoltaic module provided in an embodiment of this application.

[0027] Explanation of reference numerals in the attached figures: 10. Substrate; 101. First region; 102. Second region; 103. Third region; 104. First surface; 105. Second surface; 106. First sub-region; 107. Second sub-region; 11. First doped portion; 12. Second doped portion; 121. First doped sub-region; 122. Second doped sub-region; 13. Passivation layer; 131. Interface passivation portion; 1311. First sub-region; 1312. Second sub-region; 132. Third doped portion; 14. First electrode; 15. Second electrode; 16. Tunneling layer; 17. 18. First conductive layer; 19. Second conductive layer; 10. First conductive sub-section; 11. Second conductive sub-section; 12. Passivation film; 23. Initial doped section; 24. Initial passivation layer; 35. Bottom cell; 36. Perovskite cell; 37. First transport layer; 38. Perovskite functional layer; 39. Second transport layer; 40. Transparent conductive layer; 41. Anti-reflective layer; 42. Back contact cell; 43. Encapsulating film; 44. Cover plate; 45. First cover plate; 46. Second cover plate; 47. Solder ribbon. Detailed Implementation

[0028] As can be seen from the background technology, the performance of back contact batteries currently needs to be improved.

[0029] Therefore, this application provides a back-contact battery and its fabrication method, a tandem battery, and a photovoltaic module. In the back-contact battery provided in this application, the passivation layer includes an interface passivation portion and a third doped portion. The interface passivation portion located between the first and second doped portions can reduce the leakage current between the first and second doped portions, thereby improving the performance of the back-contact battery. The interface passivation portion located between the second doped portion and the substrate can passivate the substrate, which also helps improve the performance of the back-contact battery. Furthermore, the third doped portion can improve the efficiency of the second electrode in collecting charge carriers, which also helps improve the performance of the back-contact battery.

[0030] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0031] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0032] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0033] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0034] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0035] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0036] In the description of the embodiments of this application, "electrically connected to one component" means that both components are made of conductive materials, and the two components are in direct contact and connected or connected via other conductive materials. Therefore, when the photovoltaic module is generating electricity, there is current transfer between the two components. "Electrically contacting one component to another" means that the two components are not only in contact, but also, because both components are made of conductive materials, there is current transfer between the two components when the photovoltaic module is generating electricity.

[0037] In the accompanying drawings corresponding to the embodiments of this application, the thickness and / or area of ​​layers, films, panels, regions, etc., are enlarged for better understanding and ease of description. Throughout the specification, the same reference numerals denote the same elements. It should be understood that when describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be an intermediate component between the two components. Conversely, when describing a component on the surface of another component, or a component "directly" on another component, or a component surface on which another component is formed or disposed, it indicates that there is no intermediate component between the two components. Furthermore, when describing a component as "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0038] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Moreover, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0039] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0040] Figure 1 This is a schematic diagram of a back contact battery provided in an embodiment of this application.

[0041] refer to Figure 1The back contact battery includes: a substrate 10, a first doped portion 11, a second doped portion 12, a passivation layer 13, a first electrode 14, and a second electrode 15. The substrate 10 has a first region 101 and a second region 102, and a third region 103 located between the first region 101 and the second region 102; a first doped portion 11 is located in the first region 101 and the third region 103; a second doped portion 12 is located in the second region 102 and the third region 103, and the second doped portion 12 and the first doped portion 11 are located on the same side of the substrate 10; a passivation layer 13 is located in the second region 102 and the third region 103, and the passivation layer 13 includes an interface passivation portion 131 and a third doped portion 132. The interface passivation portion 131 is located between the substrate 10 and the second doped portion 12, and between the second doped portion 12 and the first doped portion 11. The third doped portion 132 is located between the interface passivation portion 131 and the second doped portion 12 and is spaced apart from the first doped portion 11. The dopant element in the third doped portion 132 has the same conductivity type as the dopant element in the second doped portion 12; a first electrode 14 is electrically connected to the first doped portion 11; and a second electrode 15 is electrically connected to the second doped portion 12.

[0042] The substrate 10 is used to receive light and generate photogenerated carriers. In some embodiments, the substrate 10 may be a semiconductor substrate.

[0043] In some embodiments, the material of the substrate 10 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material may be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon may be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon.

[0044] In some embodiments, the substrate 10 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium arsenide, perovskite, cadmium telluride, copper indium selenide, etc.

[0045] The substrate 10 can also be a sapphire substrate, a silicon substrate on an insulator, or a germanium substrate on an insulator.

[0046] The substrate 10 can be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type dopant element, which can be at least one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type dopant element, which can be at least one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0047] The substrate 10 has a first region 101 and a second region 102 that are alternately distributed along a first direction X, and a third region 103 located between the first region 101 and the second region 102.

[0048] It should be noted that the first region 101, the second region 102, and the third region 103 are artificially defined regions, and there is actually no substantial boundary between them. The first region 101 is the region containing the remaining portion of the first doped part 11, excluding the portion that stacks with the second doped part 12; the second region 102 is the region containing the remaining portion of the second doped part 12, excluding the portion that stacks with the first doped part 11; and the third region 103 is the region where the first doped part 11 and the second doped part 12 are stacked in the thickness direction of the substrate 10.

[0049] The substrate 10 has a first surface 104 and a second surface 105 facing each other. In some embodiments, the back-contact cell used in a single-glass photovoltaic module is considered a single-sided cell, and the first surface 104 can serve as a light-receiving surface for receiving sunlight, while the second surface 105 serves as a back-lighting surface. In some embodiments, the back-contact cell used in a double-glass module or a bifacial module is considered a bifacial cell, and both the first surface 104 and the second surface 105 can serve as light-receiving surfaces and can both be used to receive sunlight. It is understood that the back-lighting surface referred to in the embodiments of this application can also receive sunlight, but the degree of sunlight reception is weaker than that of the light-receiving surface, and therefore it is defined as a back-lighting surface.

[0050] In some embodiments, a flocking process may be performed on at least one of the first surface 104 and the second surface 105 to form a flocked surface on at least one of the first surface 104 and the second surface 105, thereby enhancing the absorption and utilization rate of the first surface 104 and / or the second surface 105 for incident light.

[0051] In some embodiments, the second surface 105 has a first region 101, a second region 102, and a third region 103.

[0052] The doping element in the first doped portion 11 and the doping element in the second doped portion 12 have different conductivity types. For example, the doping element in the first doped portion 11 is either a P-type doping element or an N-type doping element, and the doping element in the second doped portion 12 is either a P-type doping element or an N-type doping element. For a detailed explanation of the P-type and N-type doping elements, please refer to the description corresponding to the aforementioned substrate 10; further details will not be repeated here.

[0053] Unless otherwise specified, "doped elements having different conductivity types" in the embodiments of this application means that the doped element in one component is a P-type doped element and the doped element in another component is an N-type doped element, that is, the conductivity types of the doped elements are N-type and P-type, respectively. Similarly, "having the same conductivity type" in the embodiments of this application means that the doped elements in one component and the other component are both N-type doped elements, or that the doped elements in one component and the other component are both P-type doped elements. It is understood that for the limitation of having the same conductivity type, the doped elements in one component and the other component can be the same, and of course, the doped elements in one component and the other component can also be different, as long as the requirement that they are all N-type doped elements or all P-type doped elements is met.

[0054] In some embodiments, the material of the first doped portion 11 may include doped polycrystalline silicon, doped amorphous silicon, doped microcrystalline silicon, or doped nanocrystalline silicon. For example, the first doped portion 11 may be doped polycrystalline silicon with an N-type dopant element.

[0055] In some embodiments, the material of the second doped portion 12 may include doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon. For example, the second doped portion 12 may be doped amorphous silicon with p-type dopant or doped nanocrystalline silicon with p-type dopant.

[0056] Figure 2 This is a schematic diagram of another structure of the back contact battery provided in an embodiment of this application.

[0057] refer to Figure 1 and Figure 2 In some embodiments, the second doped portion 12 includes a first doped sub-portion 121 and a second doped sub-portion 122, wherein the first doped sub-portion 121 is located on the surface of the third doped portion 132 away from the substrate 10; and the second doped sub-portion 122 is adjacent to the first doped sub-portion 121.

[0058] The first doped sub-part 121 is the portion of the second doped part 12 that is stacked with the third doped part 132 along the thickness direction of the substrate 10.

[0059] Alternatively, the substrate 10 may have a first sub-region 106 and a second sub-region 107, with a second doped portion 12 located on both sub-regions 106 and 107, and a third doped portion 132 located in the first sub-region 106. The first sub-region 106 is the area where the third doped portion 132 is located; the second sub-region 107 is the area containing the remaining portion of the second doped portion 12, excluding the portion stacked with the third doped portion 132. Specifically, the first doped sub-region 121 is located in the first sub-region 106, and the second doped sub-region 122 is located in the second sub-region 107. It should be noted that the first sub-region 106 and the second sub-region 107 are artificially defined regions; in reality, there is no substantial boundary between them.

[0060] The first doped sub-section 121 is electrically connected to the second electrode 15, and the second electrode 15 overlaps with the first doped sub-section 121 along the thickness direction of the substrate 10. In this way, the conductivity of the first doped sub-section 121 can be improved by increasing the crystallinity and / or grain size of the first doped sub-section 121, thereby improving the efficiency of the second electrode 15 in collecting charge carriers.

[0061] At least a portion of the second doped sub-section 122 is located on the third region 103. That is, at least a portion of the second doped sub-section 122 is located on the side of the first doped section 11 facing away from the substrate. When the back contact battery is shielded or experiences localized abnormal heating, a leakage path can be formed between the second doped sub-section 122 located in the third region 103 and the first doped section 11. This prevents the current from being entirely concentrated in the shielded or abnormally heated area of ​​the back contact battery, thereby reducing the current density in the shielded or abnormally heated area and helping to reduce the heating power in the shielded or abnormally heated area, thus improving the hot spot effect of the back contact battery. In short, setting at least a portion of the second doped sub-section 122 in the third region is beneficial for improving the hot spot effect of the back contact battery.

[0062] In other embodiments, the second doped sub-section 122 may also be located only in the second region 102.

[0063] In some embodiments, the crystallinity of the first doped sub-section 121 can be greater than that of the second doped sub-section 122. A higher crystallinity of the first doped sub-section 121 results in a lower sheet resistance and stronger conductivity. Since the first doped sub-section 121 is electrically connected to the second electrode 15, the efficiency of the second electrode 15 in collecting charge carriers can be improved, thereby enhancing the performance of the back contact battery. Conversely, a lower crystallinity of the second doped sub-section 122 results in a higher sheet resistance and weaker conductivity. This hinders current flow between the first doped section 11 and the second doped sub-section 122, preventing excessive current in the leakage channel between them and ensuring a high photoelectric conversion efficiency for the back contact battery.

[0064] In other embodiments, the grain size of the first doped sub-section 121 can be larger than the grain size of the second doped sub-section 122. The larger grain size of the first doped sub-section 121 results in a lower sheet resistance and stronger conductivity. Furthermore, the first doped sub-section 121 is electrically connected to the second electrode 15, thereby improving the carrier collection efficiency of the second electrode 15 and thus enhancing the performance of the back contact cell. Conversely, the smaller grain size of the second doped sub-section 122 results in a higher sheet resistance and weaker conductivity, hindering current flow between the first doped section 11 and the second doped sub-section 122. This prevents excessive current in the leakage path between the first doped section 11 and the second doped sub-section 122, ensuring a high photoelectric conversion efficiency for the back contact cell.

[0065] In some embodiments, the crystallinity of the first doped sub-section 121 can be greater than that of the second doped sub-section 122, and the grain size of the first doped sub-section 121 is larger than that of the second doped sub-section 122. The larger crystallinity and grain size of the first doped sub-section 121 result in a lower sheet resistance and stronger conductivity. Since the first doped sub-section 121 is electrically connected to the second electrode 15, the efficiency of the second electrode 15 in collecting charge carriers can be improved, thereby enhancing the performance of the back contact battery. Conversely, the smaller crystallinity and grain size of the second doped sub-section 122 result in a higher sheet resistance and weaker conductivity. This hinders current flow between the first doped section 11 and the second doped sub-section 122, preventing excessive current in the leakage path between them and ensuring a high photoelectric conversion efficiency for the back contact battery.

[0066] It should be noted that grain size refers to the diameter of the grains.

[0067] In some embodiments, the crystallinity of the first doped sub-section 121 can be 20% to 80%. Optionally, the crystallinity of the first doped sub-section 121 can be 20% to 40%, 40% to 60%, or 60% to 80%. For example, the crystallinity of the first doped sub-section 121 is 20%, 30%, 40%, 50%, 60%, 70%, or 80%. A higher crystallinity of the first doped sub-section 121 within the above range results in a lower sheet resistance, which can improve the efficiency of the second electrode 15 in collecting charge carriers, thereby improving the performance of the back contact battery.

[0068] The crystallinity of the second doped sub-section 122 is 0% to 10%. Optionally, the crystallinity of the second doped sub-section 122 can be 0% to 3%, 3% to 7%, or 7% to 10%. For example, the crystallinity of the second doped sub-section 122 is 0%, 1.5%, 3%, 5%, 7%, 8.5%, or 10%. Since the crystallinity of the second doped sub-section 122 is within the above range, a smaller crystallinity can prevent the sheet resistance of the second doped sub-section 122 from being too small due to an excessively large crystallinity, thus avoiding excessive leakage current between the first doped section 11 and the second doped sub-section 122.

[0069] It should be noted that the crystallinity of the first doped sub-section 121 (hereinafter referred to as the first crystallinity) refers to the average crystallinity of each region in the first doped sub-section 121. In other words, the first crystallinity reflects the average degree of crystallinity of the first doped sub-section 121. In some cases, the crystallinity of each region in the first doped sub-section 121 is within the range of the first crystallinity; in other cases, the crystallinity of most regions in the first doped sub-section 121 is within the range of the first crystallinity, while the crystallinity of a small portion is not within the range of the first crystallinity, but the overall average crystallinity of the first doped sub-section 121 is the first crystallinity.

[0070] Similarly, the crystallinity of the second doped sub-section 122 (hereinafter referred to as the second crystallinity) refers to the average crystallinity of each region in the second doped sub-section 122. In other words, the second crystallinity reflects the average degree of crystallinity of the second doped sub-section 122. In some cases, the crystallinity of each region in the second doped sub-section 122 is within the range of the second crystallinity; in other cases, the crystallinity of most regions in the second doped sub-section 122 is within the range of the second crystallinity, while the crystallinity of a small portion is not within the range of the second crystallinity, but the overall average crystallinity of the second doped sub-section 122 is the second crystallinity.

[0071] The average crystallinity of the first doped sub-section 121 can be measured by selecting several sampling points at different locations on the first doped sub-section 121 and calculating the average crystallinity of these sampling points. That is, the average crystallinity of the first doped sub-section 121 can be measured using a sampling method. Similarly, the average crystallinity of the second doped sub-section 122 can also be measured using a sampling method.

[0072] In addition, X-ray diffraction, differential scanning calorimetry, nuclear magnetic resonance, infrared spectroscopy and other methods can be used to measure the crystallinity of the first doped sub-part 121 and the crystallinity of the second doped sub-part 122.

[0073] In other embodiments, the crystallinity of the first doped sub-section 121 and the crystallinity of the second doped sub-section 122 can both be 0%. That is, the first doped sub-section 121 and the second doped sub-section 122 can both be doped amorphous silicon.

[0074] It is understandable that as grain size increases, grain boundaries decrease, carrier scattering within the grain decreases, mobility increases, and conductivity improves. In other words, grain size is positively correlated with conductivity.

[0075] In some embodiments, the grain size of the first doped sub-section 121 can be 3 nm to 200 nm. Optionally, the grain size of the first doped sub-section 121 can be 3 nm to 20 nm, 20 nm to 50 nm, 50 nm to 100 nm, or 100 nm to 200 nm. For example, the grain size of the first doped sub-section 121 can be 3 nm, 8 nm, 11.5 nm, 20 nm, 35 nm, 50 nm, 75 nm, 100 nm, 120 nm, 150 nm, 180 nm, or 200 nm. When the grain size of the first doped sub-section 121 is within the above range, a larger grain size results in better conductivity of the first doped sub-section 121, which can improve the efficiency of the second electrode 15 in collecting charge carriers, thereby improving the performance of the back contact battery.

[0076] The grain size of the second doped sub-section 122 can be less than or equal to 1 nm. Optionally, the grain size of the second doped sub-section 122 can be 0.01 nm to 0.3 nm, 0.3 nm to 0.7 nm, or 0.7 nm to 1 nm. For example, the grain size of the second doped sub-section 122 can be 0.01 nm, 0.1 nm, 0.2 nm, 0.3 nm, 0.5 nm, 0.7 nm, 0.85 nm, or 1 nm. When the grain size of the second doped sub-section 122 is within the above range, the grain size is moderate, which avoids excessive conductivity of the second doped sub-section 122 due to an excessively large grain size, thus preventing excessive leakage current between the first doped section 11 and the second doped sub-section 122. It also avoids excessively poor conductivity of the second doped sub-section 122 due to an excessively small grain size, thus preventing any impact on the efficiency of the second electrode 15 in collecting charge carriers.

[0077] It should be noted that the grain size of the first doped sub-section 121 (hereinafter referred to as the first grain size) refers to the average grain size of each region in the first doped sub-section 121. In some cases, the grain size of each region in the first doped sub-section 121 is within the range of the first grain size; in other cases, the grain size of most regions in the first doped sub-section 121 is within the range of the first grain size, while a small portion of the grain size is outside the range of the first grain size, but the overall average grain size of the first doped sub-section 121 is the first grain size. Similarly, the grain size of the second doped sub-section 122 (hereinafter referred to as the second grain size) refers to the average grain size of each region in the second doped sub-section 122. In some cases, the grain size of each region in the second doped sub-section 122 is within the range of the second grain size; in other cases, the grain size of most regions in the second doped sub-section 122 is within the range of the second grain size, and the grain size of a small portion is not within the range of the second grain size, but the overall average grain size of the second doped sub-section 122 is the second grain size.

[0078] It should also be noted that, compared to the entire back-contact cell / photovoltaic module, the grain size of the first doped sub-section 121 is extremely small, and the number of grains in the first doped sub-section 121 is extremely large. Therefore, actual measurement cannot exhaustively measure all grains in the entire first doped sub-section 121. Instead, several sampling points are selected at different locations in the first doped sub-section 121, and the average grain size of these sampling points is measured and calculated to obtain the average grain size of the first doped sub-section 121. That is, the average grain size of the first doped sub-section 121 can be measured using a sampling method. For example, the average grain size of 5 sampling points in the first doped sub-section 121 can be measured and calculated as the average grain size of the first doped sub-section 121. Similarly, the average grain size of the second doped sub-section 122 can also be measured using a sampling method.

[0079] In addition, testing equipment such as optical microscopes, laser confocal microscopes, scanning electron microscopes, transmission electron microscopes, X-ray diffractometers, and atomic force microscopes can be used to measure the grain size of the first doped sub-part 121 and the grain size of the second doped sub-part 122.

[0080] In other embodiments, the first doped sub-section 121 may be doped amorphous silicon, in which case the first doped sub-section 121 does not contain grains; the second doped sub-section 122 may be doped amorphous silicon, in which case the second doped sub-section 122 does not contain grains.

[0081] In some embodiments, the second doped portion 12 includes a first doped sub-portion 121 and a second doped sub-portion 122. The first doped sub-portion 121 is located on the surface of the third doped portion 132 facing away from the substrate 10. The second doped sub-portion 122 is adjacent to the first doped sub-portion 121. The doping concentration of the doping element in the first doped sub-portion 121 is greater than the doping concentration of the doping element in the second doped sub-portion 122. A higher doping concentration in the first doped sub-portion 121 helps reduce its resistance, thereby improving the performance of the back contact battery. It also helps reduce the contact resistance between the first doped sub-portion 121 and the first conductive layer 17, further improving the performance of the back contact battery. Conversely, a lower doping concentration in the second doped sub-portion 122 helps reduce parasitic absorption, also improving the performance of the back contact battery.

[0082] In some embodiments, the doping concentration of the dopant element in the first doped sub-part 121 can be 5E17 atoms / cm³. 3 ~3E20atoms / cm 3 Optionally, the doping concentration of the dopant element in the first doped sub-section 121 can be 5E17 atoms / cm³. 3 ~5E18atoms / cm3 5E18atoms / cm 3 ~5E19atoms / cm 3 Or 5E19 atoms / cm 3 ~3E20atoms / cm 3 For example, the doping concentration of the dopant element in the first doped sub-section 121 can be 5E17 atoms / cm³. 3 8E17atoms / cm 3 1E18atoms / cm 3 5E18atoms / cm 3 1E19atoms / cm 3 5E19atoms / cm 3 8E19atoms / cm 3 1E20atoms / cm 3 Or 3E20 atoms / cm 3 .

[0083] In some embodiments, the doping concentration of the dopant element in the second doped sub-section 122 can be 1E17 atoms / cm³. 3 ~2E20atoms / cm 3 Optionally, the doping concentration of the dopant element in the second doped sub-section 122 can be 1E17 atoms / cm³. 3 ~1E18atoms / cm 3 1E18atoms / cm 3 ~1E19atoms / cm 3 Or 1E19 atoms / cm 3 ~2E20atoms / cm 3 For example, the doping concentration of the dopant element in the second doped sub-section 122 can be 1E17 atoms / cm³. 3 5E17atoms / cm 3 1E18atoms / cm 3 5E18atoms / cm 3 1E19atoms / cm 3 5E19atoms / cm 3 8E19atoms / cm 3 1E20atoms / cm 3 Or 2E20atoms / cm 3 .

[0084] It should be noted that the doping concentration of the dopant element in the first doped sub-section 121 refers to the average doping concentration of activated and unactivated dopant elements contained in the first doped sub-section 121. This can be obtained using secondary ion mass spectrometry or transmission electron microscopy. Similarly, the doping concentration of the dopant element in the second doped sub-section 122 refers to the average doping concentration of activated and unactivated dopant elements in the second doped sub-section 122. This can also be obtained using secondary ion mass spectrometry or transmission electron microscopy.

[0085] In some embodiments, the effective doping concentration of the dopant element in the first doped sub-section 121 is greater than the effective doping concentration of the dopant element in the second doped sub-section 122. A higher effective doping concentration in the first doped sub-section 121 helps reduce the resistance of the first doped sub-section 121, thereby improving the performance of the back contact battery. It also helps reduce the contact resistance between the first doped sub-section 121 and the first conductive layer 17, thus further improving the performance of the back contact battery.

[0086] It should be noted that the effective doping concentration of the dopant element in the first doped sub-section 121 refers to the average doping concentration of the activated dopant element in the first doped sub-section 121, which can be obtained using the electrochemical capacitance-voltage method. Similarly, the effective doping concentration of the dopant element in the second doped sub-section 122 refers to the average doping concentration of the activated dopant element in the second doped sub-section 122, which can also be obtained using the electrochemical capacitance-voltage method.

[0087] In some embodiments, the effective doping concentration of the dopant element in the first doped sub-part 121 can be 2E16 atoms / cm². 3 ~2E20atoms / cm 3 Optionally, the effective doping concentration of the dopant element in the first doped sub-section 121 can be 2E16 atoms / cm². 3 ~1E17atoms / cm 3 1E17atoms / cm 3 ~5E18atoms / cm 3 5E18atoms / cm 3 ~5E19atoms / cm 3 Or 5E19 atoms / cm 3 ~2E20atoms / cm 3 For example, the effective doping concentration of the dopant element in the first doped sub-section 121 can be 2E16 atoms / cm². 3 6E16atoms / cm 3 1E17atoms / cm 3 8E17atoms / cm 31E18atoms / cm 3 5E18atoms / cm 3 1E19atoms / cm 3 5E19atoms / cm 3 8.5E19 atoms / cm 3 Or 2E20atoms / cm 3 .

[0088] In some embodiments, the effective doping concentration of the dopant element in the second doped sub-section 122 can be 1E16 atoms / cm². 3 ~1E20atoms / cm 3 Optionally, the effective doping concentration of the dopant element in the second doped sub-section 122 can be 1E16 atoms / cm². 3 ~1E17atoms / cm 3 1E17atoms / cm 3 ~1E18atoms / cm 3 1E18atoms / cm 3 ~1E19atoms / cm 3 Or 1E19 atoms / cm 3 ~1E20atoms / cm 3 For example, the effective doping concentration of the dopant element in the second doped sub-section 122 can be 1E16 atoms / cm². 3 5E16 atoms / cm 3 1E17atoms / cm 3 5E17atoms / cm 3 1E18atoms / cm 3 5E18atoms / cm 3 1E19atoms / cm 3 5E19atoms / cm 3 Or 1E20 atoms / cm 3 .

[0089] The passivation layer 13 is used to saturate the dangling bonds of the second surface 105, reduce the defect state density of the second surface 105, and reduce the recombination centers of the second surface 105 to reduce the carrier recombination rate.

[0090] The passivation layer 13 includes an interface passivation portion 131. A portion of the interface passivation portion 131 is located on the surface of the substrate 10 and can be used to passivate the substrate 10, thereby improving the performance of the back contact battery; another portion of the interface passivation portion 131 is located between the first doped portion 11 and the second doped portion 12, which can reduce the leakage current between the first doped portion 11 and the second doped portion 12, thereby improving the performance of the back contact battery.

[0091] The interface passivation section 131 is called the "interface passivation section" because, relative to the second region 102, the interface passivation section 131 mainly serves to passivate the surface defects of the substrate 10.

[0092] In some examples, the material of the interface passivation portion 131 may include, but is not limited to, amorphous silicon (such as intrinsic amorphous silicon or micro-doped amorphous silicon), silicon oxide, silicon nitride, silicon oxynitride, or silicon carbide.

[0093] It should be noted that in some examples, the interface passivation portion 131 may be free of doped elements. In other examples, the interface passivation portion 131 may contain doped elements, but the doping content of the doped elements in the interface passivation portion 131 is much smaller than that in the third doped portion 132 and can be ignored. The doped elements present in the interface passivation portion 131 may be due to the diffusion of doped elements from the third doped portion 132 towards the substrate 10.

[0094] Continue to refer to Figure 1 and Figure 2 In some embodiments, the interface passivation portion 131 includes a first sub-portion 1311 and second sub-portions 1312 located on both sides of the first sub-portion 1311. The first sub-portion 1311 is located between the third doped portion 132 and the substrate 10. The thickness of the first sub-portion 1311 is less than the thickness of the second sub-portion 1312. The smaller thickness of the first sub-portion 1311 avoids affecting the efficiency of the second electrode 15 in collecting charge carriers due to its larger thickness, thereby improving the performance of the back contact battery. Furthermore, at least a portion of the second sub-portion 1312 is located between the first doped portion 11 and the second doped portion 12. The larger thickness of the second sub-portion 1312 can reduce the leakage current between the first doped portion 11 and the second doped portion 12, thereby improving the performance of the back contact battery.

[0095] In some embodiments, the thickness of the first sub-part 1311 can be 1 nm to 4 nm. Optionally, the thickness of the first sub-part 1311 can be 1 nm to 2 nm, 2 nm to 3 nm, or 3 nm to 4 nm. For example, the thickness of the first sub-part 1311 can be 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, or 4 nm. When the thickness of the first sub-part 1311 is within the above range, it can effectively passivate the substrate 10 while avoiding the impact of a large thickness of the first sub-part 1311 on the efficiency of the second electrode 15 in collecting charge carriers, thereby improving the performance of the back contact battery.

[0096] The thickness of the second sub-part 1312 can be 7nm to 20nm. Optionally, the thickness of the second sub-part 1312 can be 7nm to 11nm, 11nm to 15nm, or 15nm to 20nm. For example, the thickness of the second sub-part 1312 can be 7nm, 9nm, 11nm, 13nm, 15nm, 17.5nm, or 20nm. The thickness of the second sub-part 1312 is within the above range. A larger thickness of the second sub-part 1312 can effectively reduce the leakage current between the first doped part 11 and the second doped part 12, thereby improving the performance of the back contact battery.

[0097] In other embodiments, the thickness of the first sub-part may also be equal to the thickness of the second sub-part.

[0098] The conductivity type of the dopant element in the third doped section 132 is the same as that of the dopant element in the second doped section 12. The presence of the third doped section 132, together with the second doped section 12, assists the second electrode 15 in collecting charge carriers, thereby improving the performance of the back contact battery. In some examples, the dopant element in the third doped section 132 is the same as that in the second doped section 12.

[0099] The material of the third doped part 132 may include, but is not limited to, amorphous silicon, microcrystalline silicon, nanocrystalline silicon, silicon oxide, silicon nitride, silicon oxynitride, or silicon carbide.

[0100] In some embodiments, the thickness of the interface passivation portion 131 located between the third doped portion 132 and the substrate 10 is a first thickness, that is, the thickness of the first sub-portion 1311 is a first thickness, and the ratio of the thickness of the third doped portion 132 to the first thickness can be 1 to 15. Optionally, the ratio of the thickness of the third doped portion 132 to the first thickness can be 1 to 5, 5 to 10, or 10 to 15. For example, the ratio of the thickness of the third doped portion 132 to the first thickness can be 1, 2, 2.5, 5, 7.5, 10, 12.5, or 15. Since the ratio of the thickness of the third doped portion 132 to the first thickness is within the above range, the thickness of the third doped portion 132 can be relatively large, which can ensure that the third doped portion 132 has a sufficient thickness to promote the collection of carriers by the second electrode 15, and also makes the thickness of the first sub-portion 1311 relatively small, which can avoid affecting the efficiency of the second electrode 15 in collecting carriers due to the large thickness of the first sub-portion 1311.

[0101] In some embodiments, the thickness of the third doped portion 132 can be 4 nm to 15 nm. Optionally, the thickness of the third doped portion 132 can be 4 nm to 8 nm, 8 nm to 12 nm, or 12 nm to 15 nm. For example, the thickness of the third doped portion 132 can be 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 13.5 nm, or 15 nm. The thickness of the third doped portion 132 is within the above ranges. A larger thickness of the third doped portion 132 ensures sufficient thickness to facilitate carrier collection by the second electrode 15, and also avoids resource waste due to excessive thickness of the third doped portion 132.

[0102] In some embodiments, the first thickness can be 1 nm to 4 nm. Optionally, the first thickness can be 1 nm to 2 nm, 2 nm to 3 nm, or 3 nm to 4 nm. For example, the thickness of the first sub-part 1311 can be 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, or 4 nm. The thickness of the first sub-part 1311 is within the above range, which can effectively passivate the substrate 10 while avoiding the impact of a large thickness of the first sub-part 1311 on the efficiency of the second electrode 15 in collecting carriers from the substrate 10, thereby improving the performance of the back contact battery.

[0103] In some embodiments, the doping concentration of the dopant element in the third doped portion 132 can be 5E17 atoms / cm³. 3 ~5E19atoms / cm 3 Optionally, the doping concentration of the dopant element in the third doped section 132 can be 5E17 atoms / cm³. 3 ~1E18atoms / cm 3 1E18atoms / cm 3~1E19atoms / cm 3 Or 1E19 atoms / cm 3 ~5E19atoms / cm 3 For example, the doping concentration of the dopant element in the third doped section 132 can be 5E17 atoms / cm³. 3 8E17atoms / cm 3 1E18atoms / cm 3 5E18atoms / cm 3 1E19atoms / cm 3 3E19atoms / cm 3 Or 5E20 atoms / cm 3 The doping concentration of the doping element in the third doped section 132 is within the above-mentioned range, which can effectively help the second electrode 15 collect charge carriers.

[0104] It should be noted that the doping concentration of the dopant element in the third doped section 132 here refers to the average doping concentration of the activated and unactivated dopant elements in the third doped section 132. This concentration can be obtained using secondary ion mass spectrometry or transmission electron microscopy.

[0105] In some embodiments, along the first direction X, the ratio of the length of the third doped portion 132 to the length of the second doped portion 12 can be 0.06 to 0.7. Optionally, the ratio of the length of the third doped portion 132 to the length of the second doped portion 12 can be 0.06 to 0.1, 0.1 to 0.3, or 0.3 to 0.7. For example, the ratio of the length of the third doped portion 132 to the length of the second doped portion 12 is 0.06, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7. When the ratio of the length of the third doped portion 132 to the length of the second doped portion 12 is within the above range, it can be ensured that the third doped portion 132 is of sufficient length to help the second electrode 15 collect charge carriers.

[0106] In some embodiments, the length of the third doped portion 132 along the first direction X can be 80 μm to 260 μm. Optionally, the length of the third doped portion 132 along the first direction X can be 80 μm to 140 μm, 140 μm to 200 μm, or 200 μm to 260 μm. For example, the length of the third doped portion 132 along the first direction X can be 80 μm, 100 μm, 110 μm, 140 μm, 170 μm, 200 μm, 230 μm, or 260 μm.

[0107] The first electrode 14 is located in the first region 101 and is electrically connected to the first doped portion 11 for collecting charge carriers. The second electrode 15 is located in the second region 102 and is electrically connected to the second doped portion 12 for collecting charge carriers.

[0108] The metallic material of the first electrode 14 includes at least one of gold, silver, copper, nickel, aluminum, and tin. The metallic material of the second electrode 15 includes at least one of gold, silver, copper, nickel, aluminum, and tin.

[0109] In some embodiments, the second electrode 15 is located in the first sub-region 106.

[0110] In some embodiments, the second electrode 15 is electrically connected to the second doped portion 12, and the second electrode 15 overlaps with the first doped portion 121 in the thickness direction along the substrate 10. The first doped portion 121 has superior conductivity, thereby improving the ability of the second electrode 15 to collect charge carriers.

[0111] Continue to refer to Figure 2 In some embodiments, the back contact battery further includes a tunneling layer 16 located between the first doped portion 11 and the substrate 10. The tunneling layer 16 is used to saturate the dangling bonds of the second surface 105, reduce the defect state density of the second surface 105, reduce the recombination centers of the second surface 105 to reduce the carrier recombination rate, and also to form band bends to achieve selective carrier transport, thereby improving the efficiency of the first electrode 14 in collecting carriers.

[0112] The material of the tunneling layer 16 may include, but is not limited to, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride.

[0113] The back contact battery further includes a first conductive layer 17 located in the first region 101 and a second conductive layer 18 located in the second region 102. The first conductive layer 17 is located on the side of the first doped portion 11 facing away from the substrate 10 and is electrically connected to the first electrode 14. The second conductive layer 18 is located on the side of the second doped portion 12 facing away from the substrate 10 and is electrically connected to the second electrode 15.

[0114] The first conductive layer 17 can reduce the contact resistance between the first electrode 14 and the first doped portion 11, thereby improving the efficiency of the first electrode 14 in collecting charge carriers. The material of the first conductive layer 17 may include at least one of fluorine-doped tin oxide, aluminum-doped zinc oxide, tin-doped indium oxide, tungsten-doped indium oxide, molybdenum-doped indium oxide, cerium-doped indium oxide, and indium hydroxide.

[0115] The second conductive layer 18 can reduce the contact resistance between the second electrode 15 and the second doped portion 12, thereby improving the efficiency of the second electrode 15 in collecting charge carriers. The material of the second conductive layer 18 may include at least one of fluorine-doped tin oxide, aluminum-doped zinc oxide, tin-doped indium oxide, tungsten-doped indium oxide, molybdenum-doped indium oxide, cerium-doped indium oxide, and indium hydroxide.

[0116] In some embodiments, the second conductive layer 18 may include a first conductive sub-part 181 and a second conductive sub-part 182 located on at least one side of the first conductive sub-part 181. The first conductive sub-part 181 is located on the side of the third doped portion 132 away from the substrate 10. The first conductive sub-part 181 is located in the first sub-region 106, and the second conductive sub-part 182 is located in the second sub-region 107.

[0117] The thickness of the first conductive portion 181 can be greater than or equal to the thickness of the second conductive portion 182. When the thickness of the first conductive portion 181 is equal to the thickness of the second conductive portion 182, it facilitates the fabrication of the second conductive layer 18. When the thickness of the first conductive portion 181 is greater than the thickness of the second conductive portion 182, the sheet resistance of the thicker first conductive portion 181 is smaller, which facilitates the collection of charge carriers by the second electrode 15. The parasitic absorption of the thinner second conductive portion 182 is smaller, which can improve the performance of the back contact battery.

[0118] In some embodiments, the thickness of the first conductive electronic portion 181 can be 30 nm to 80 nm. Optionally, the thickness of the first conductive electronic portion 181 can be 30 nm to 45 nm, 45 nm to 60 nm, or 60 nm to 80 nm. For example, the thickness of the first conductive electronic portion 181 can be 30 nm, 37.5 nm, 45 nm, 52.5 nm, 60 nm, 70 nm, or 80 nm.

[0119] In some embodiments, the thickness of the second conductive electronic portion 182 can be 25 nm to 70 nm. Optionally, the thickness of the second conductive electronic portion 182 can be 25 nm to 40 nm, 40 nm to 55 nm, or 55 nm to 70 nm. For example, the thickness of the second conductive electronic portion 182 can be 25 nm, 32.5 nm, 40 nm, 47.5 nm, 55 nm, 62.5 nm, or 70 nm.

[0120] Figure 3 This is another schematic diagram of the back contact battery provided in the embodiments of this application.

[0121] refer to Figure 3 In some embodiments, the second conductive layer 18 may be located only in the first sub-region 106, which helps to save on the manufacturing cost of the back contact battery.

[0122] Continue to refer to Figure 3In some embodiments, the back contact battery also includes a passivation film 19 located on the first surface 104.

[0123] The passivation film 19 is used to passivate defects on the first surface 104, reduce the defect state density of the first surface 104, reduce the recombination of photogenerated carriers on the first surface 104, thereby improving the open-circuit voltage and efficiency of the back contact cell.

[0124] The material of the passivation film 19 can be one of silicon oxide, aluminum oxide, silicon nitride, and silicon oxynitride.

[0125] The passivation film 19 can be a single-layer structure or a multi-layer structure. In the case of a multi-layer structure, the materials of different layers can be different from each other, or some layers can be made of the same material but different from the materials of other layers. For example, the passivation film 19 can be a multi-layer structure of silicon nitride layers and aluminum oxide layers.

[0126] In the back contact battery provided in this application, the interface passivation portion 131 located between the first doped portion 11 and the second doped portion 12 can reduce the leakage current between the first doped portion 11 and the second doped portion 12, thereby improving the performance of the back contact battery. The interface passivation portion 131 located between the second doped portion 12 and the substrate 10 can passivate the substrate 10, which also helps to improve the performance of the back contact battery. In addition, the third doped portion 132 is located between the interface passivation portion 131 and the second doped portion 12, and the doping element in the third doped portion 132 has the same conductivity type as the doping element in the second doped portion 12. Since the second electrode 15 is electrically connected to the second doped portion 12, the third doped portion 132 can improve the efficiency of the second electrode 15 in collecting charge carriers, which also helps to improve the performance of the back contact battery.

[0127] Accordingly, another aspect of this application embodiment also provides a method for preparing a back contact battery. This method for preparing a back contact battery can produce the back contact battery in any of the above embodiments. It should be noted that parts that are the same as or corresponding to those in the foregoing embodiments can be referred to the corresponding descriptions in the foregoing embodiments, and will not be repeated below.

[0128] Figure 4 This is a schematic diagram of the structure of an initial battery provided in the preparation method of the back contact battery provided in the embodiments of this application.

[0129] refer to Figure 1 and Figure 4The method for fabricating a back-contact battery includes: providing an initial battery, the initial battery comprising: a substrate 10, a first doped portion 11, an initial doped portion 20, and an initial passivation layer 21. The substrate 10 has a first region 101 and a second region 102, and a third region 103 located between the first region 101 and the second region 102; the first doped portion 11 is located in the first region 101 and the third region 103; the initial doped portion 20 is located in the second region 102 and the third region 103, and the initial doped portion 20 and the first doped portion 11 are located on the same side of the substrate 10; the initial passivation layer 21 is located in the second region 102 and the third region 103, and is located between the substrate 10 and the initial doped portion 20, and between the initial doped portion 20 and the first doped portion 11. A doping process is performed to transform the initial doped portion 20 into the second doped portion 12, and to transform the initial passivation layer 21 of a certain thickness separated from the first doped portion 11 into the third doped portion 132, with the remaining portion of the initial passivation layer 21 serving as the interface passivation portion 131; wherein the doping elements in the third doped portion 132 have the same conductivity type as the doping elements in the second doped portion 12; a first electrode 14 and a second electrode 15 are formed, with the first electrode 14 electrically connected to the first doped portion 11 and the second electrode 15 electrically connected to the second doped portion 12.

[0130] The initial doped section 20 contains a doped element, and the conductivity type of the doped element in the initial doped section 20 is different from that of the doped element in the first doped section 11.

[0131] The doping process transforms the initial doped portion 20 into the second doped portion 12, and transforms the initial passivation layer 21, a portion of which is spaced from the first doped portion 11, into the third doped portion 132. The remaining portion of the initial passivation layer 21 serves as the interface passivation portion 131. This results in a final back contact cell where a portion of the interface passivation portion 131 is located between the first doped portion 11 and the second doped portion 12, reducing leakage current between them and improving the performance of the back contact cell. The interface passivation portion 131 located between the second doped portion 12 and the substrate 10 passivates the substrate 10, further enhancing the performance of the back contact cell. Additionally, the third doped portion 132 improves the carrier collection efficiency of the second electrode 15, also contributing to improved back contact cell performance.

[0132] refer to Figure 1 , Figure 2 and Figure 4In some embodiments, the second doped portion 12 includes a first doped sub-portion 121 and a second doped sub-portion 122. The first doped sub-portion 121 is located on the surface of the third doped portion 132 facing away from the substrate 10; the second doped sub-portion 122 is adjacent to the first doped sub-portion 121. The region where the first doped sub-portion 121 is located is the region where the doping process is performed (i.e., the first sub-region 106). That is, the initial doped portion 20 of the first sub-region 106 is subjected to a doping process, transforming the initial doped portion 20 into the second doped portion 12, which includes the first doped sub-portion 121 and the second doped sub-portion 122.

[0133] In some embodiments, the doping process includes laser processing. Laser processing can cause some of the dopant elements located in the initial doped portion 20 of the first sub-region 106 to enter the initial passivation layer 21, resulting in a third doped portion 132. Additionally, the thermal effect of laser processing can be used to activate the dopant elements in the initial doped portion 20 of the first sub-region 106, thereby increasing the number of activated dopant elements in the final first doped sub-region 121. This allows the effective doping concentration of the dopant elements in the first doped sub-region 121 to be greater than that in the second doped sub-region 122. A higher effective doping concentration in the first doped sub-region 121 helps reduce the resistance of the first doped sub-region 121, thus improving the performance of the back contact battery. It also helps reduce the contact resistance between the first doped sub-region 121 and the first conductive layer 17, further improving the performance of the back contact battery.

[0134] In some embodiments, the wavelength of laser processing can be 325nm to 532nm. Optionally, the wavelength of laser processing can be 325nm to 400nm, 400nm to 450nm, 450nm to 500nm, or 500nm to 532nm. For example, the wavelengths of laser processing are 325nm, 350nm, 375nm, 400nm, 425nm, 450nm, 475nm, 500nm, 516nm, or 532nm.

[0135] In some embodiments, the energy density of the laser treatment can be 150 mJ / cm². 2 ~5000mJ / cm 2 Optionally, the energy density of the laser treatment can be 150 mJ / cm³. 2 ~1000mJ / cm 2 1000mJ / cm 2 ~2000mJ / cm 2 2000mJ / cm 2 ~3000mJ / cm 2 3000mJ / cm 2 ~4000mJ / cm2 Or 4000mJ / cm 2 ~5000mJ / cm 2 For example, the energy density of laser treatment can be 150 mJ / cm². 2 300mJ / cm 2 575mJ / cm 2 800mJ / cm 2 1000mJ / cm 2 1500mJ / cm 2 2000mJ / cm 2 2500mJ / cm 2 3000mJ / cm 2 3500mJ / cm 2 4500mJ / cm 2 Or 5000mJ / cm 2 .

[0136] In some examples, when the length of the substrate 10 is 182 mm and the width of the substrate 10 is 105 mm, the process time for laser processing can be 0.2 s to 0.5 s, for example, 0.2 s, 0.3 s, 0.4 s or 0.5 s.

[0137] It should be noted that the processing time of laser treatment is related to the size of the substrate 10 and the size of the area to be treated. The operator can adjust the processing time of laser treatment according to actual needs. This application embodiment does not limit this.

[0138] In some embodiments, the doping process includes ion implantation. Ion implantation can directly implant a dopant source into the initial doped portion 20 and the initial passivation layer 21, transforming a portion of the initial passivation layer 21 into a third doped portion 132. Ion implantation provides a dopant source, thereby increasing the doping concentration of the dopant element in the first doped sub-perimeter 121, which helps reduce the resistance of the first doped sub-perimeter 121, thus improving the performance of the back contact battery. It also helps reduce the contact resistance between the first doped sub-perimeter 121 and the first conductive layer 17, further improving the performance of the back contact battery. The dopant element in the dopant source has the same conductivity type as the dopant element in the initial doped portion 20. For example, the dopant element in the dopant source is the same as the dopant element in the initial doped portion 20.

[0139] In some embodiments, the energy of ion implantation can be 0.1 keV to 10 keV. Optionally, the energy of ion implantation can be 0.1 keV to 3 keV, 3 keV to 7 keV, or 7 keV to 10 keV. For example, the energy of ion implantation can be 0.1 keV, 1 keV, 2 keV, 3 keV, 4 keV, 5 keV, 6 keV, 7 keV, 8 keV, 8.5 keV, 9 keV, or 10 keV.

[0140] The implantation dose for ion implantation can be 1E11 ions / cm 2 ~1E17ions / cm 2 For example, the implantation dose for ion implantation treatment can be 1E11 ions / cm. 2 ~1E12ions / cm 2 1E12ions / cm 2 ~1E13ions / cm 2 1E13ions / cm 2 ~1E14ions / cm 2 1E14ions / cm 2 ~1E15ions / cm 2 1E15ions / cm 2 ~1E16ions / cm 2 or 1E16ions / cm 2 ~1E17ions / cm 2 For example, the implantation dose for ion implantation treatment can be 1E11 ions / cm. 2 5.5E11ions / cm 2 1E12ions / cm 2 5.5E12ions / cm 2 1E13ions / cm 2 5.5E13ions / cm 2 1E14ions / cm 2 5.5E14 ions / cm 2 1E15ions / cm 2 5.5E15ions / cm 2 1E16ions / cm 2 5.5E16ions / cm 2 or 1E17ions / cm 2 .

[0141] The process temperature for ion implantation can be from 25°C to 200°C. Optionally, the process temperature for ion implantation can be from 25°C to 50°C, 50°C to 100°C, 100°C to 150°C, or 150°C to 200°C. For example, the process temperature for ion implantation can be 25°C, 50°C, 75°C, 100°C, 125°C, 150°C, 175°C, or 200°C. Here, the process temperature for ion implantation is the target temperature for raising the initial cell temperature.

[0142] In some embodiments, after the doping process, the method for fabricating a back contact battery may further include removing the second doped portion 12 and the passivation layer 13 of the first region 101; forming an initial conductive layer on the side of the substrate 10 away from the first surface 104; removing at least a portion of the initial conductive layer located on the third region 103, with the remaining portion of the initial conductive layer being the first conductive layer 17 and the second conductive layer 18; forming a passivation film 19 on the first surface 104; and forming a first electrode 14 and a second electrode 15.

[0143] Accordingly, another aspect of this application embodiment also provides a stacked battery. The stacked battery includes the back contact battery described in any of the above embodiments or a back contact battery prepared by any of the above methods. It should be noted that the parts that are the same as or corresponding to the foregoing embodiments can be referred to the corresponding descriptions of the foregoing embodiments, and will not be repeated below.

[0144] Figure 5 This is a schematic diagram of a stacked battery provided in an embodiment of this application.

[0145] refer to Figure 5 The stacked battery includes a bottom cell 30 and a perovskite cell 31. The bottom cell 30 is a back contact cell in any of the foregoing embodiments, or the bottom cell is a back contact cell prepared by the preparation method of the back contact cell in any of the foregoing embodiments. The perovskite cell 31 is located on one side of the bottom cell 30.

[0146] Figure 6 Another schematic diagram of the stacked battery provided in this application embodiment.

[0147] refer to Figure 6 In some embodiments, the perovskite solar cell 31 may include: a first transport layer 311, a perovskite functional layer 312, a second transport layer 313, a transparent conductive layer 314, and an anti-reflection layer 315 stacked together. The first transport layer 311 is directly opposite the bottom solar cell 30.

[0148] In some examples, the first transport layer 311 can be one of an electron transport layer and a hole transport layer, and the second transport layer 313 can be the other of an electron transport layer and a hole transport layer.

[0149] In some embodiments, the band gap width of the perovskite cell 31 is greater than that of the bottom cell 30. Therefore, stacking the perovskite cell 31 on top of the bottom cell 30 can give the stacked cell a wider spectral response range, thereby maximizing the utilization of solar energy and improving the efficiency of the cell.

[0150] In some embodiments, the stacked battery may further include an intermediate connecting layer (not shown) for electrically connecting the bottom battery 30 and the perovskite battery 31.

[0151] In some embodiments, the intermediate connecting layer is generally a tunnel junction or a very thin metal or transparent electrode composite layer. Optionally, the intermediate connecting layer can be a transparent conductive oxide, which has good optoelectronic properties, high photon transmittance and high conductivity, thereby enabling the perovskite cell 31 and the bottom cell 30 to maintain good ohmic contact.

[0152] In some embodiments, the tandem battery can be configured as a 2T (two-terminal series / two-terminal stacked) structure or a 4T (four-terminal series / four-terminal stacked) structure. The tandem battery can also be configured as a 3T (three-terminal series / three-terminal stacked) structure. The three-terminal stacked structure is mainly used in tandem batteries manufactured by combining back-contact batteries and perovskite batteries, and it produces three electrodes. In the four-terminal stacked battery, the two sub-cells are manufactured independently, and they are only optically connected; their circuits are independent. It can be understood that the perovskite battery 31 and the bottom battery 30 are merely physically stacked, and in reality, they each output independently. Therefore, the four-terminal stacked battery will have two positive electrodes and two negative electrodes.

[0153] Accordingly, in another aspect, this application also provides a photovoltaic module, which includes a back contact cell as described in any of the above embodiments, or a back contact cell prepared by the preparation method of the back contact cell in any of the embodiments, or a tandem cell as described in the above embodiments. It should be noted that the parts that are the same as or corresponding to the foregoing embodiments can be referred to the corresponding descriptions of the foregoing embodiments, and will not be repeated below.

[0154] Figure 7 This is a partial three-dimensional schematic diagram of a cell string in a photovoltaic module provided in an embodiment of this application; Figure 8 This is a partial cross-sectional schematic diagram of a photovoltaic module provided in an embodiment of this application.

[0155] refer to Figure 7 and Figure 8The photovoltaic module includes: a cell string, which is formed by connecting multiple back-contact cells 40 as described above, or by connecting back-contact cells 40 prepared by the method for preparing back-contact cells according to any of the above embodiments, or by connecting multiple stacked cells as described in the above embodiments. The photovoltaic module also includes an encapsulating film 41 and a cover plate 42; the encapsulating film 41 is used to cover the surface of the cell string; the cover plate 42 is used to cover the surface of the encapsulating film facing away from the cell string.

[0156] In some embodiments, the back contact battery 40 can be electrically connected in the form of a whole cell or sliced ​​cells to form multiple battery strings, which are electrically connected in series and / or parallel. A sliced ​​cell refers to a cell formed by cutting a complete whole cell. Segmented cells can be two-slice cells, three-slice cells, or four-slice cells, etc.

[0157] Multiple back-contact batteries 40 can be electrically connected through solder strips 43.

[0158] In some embodiments, the encapsulating film 41 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the first and second surfaces of the back contact battery 40, and the second encapsulating layer covers the other of the first and second surfaces of the back contact battery 40. Specifically, at least one of the first and second encapsulating layers can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate (EVA) film, polyethylene octene elastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first and second encapsulating layers can also be an EP film, an EPE film, or a PVP film. Among them, EP film refers to a co-extruded film composed of stacked EVA film and POE film; EPE film refers to a co-extruded film formed by sequentially stacking EVA film, POE film, and EVA film; and PVP film refers to a co-extruded film formed by stacking POE film, EVA film, and POE film. Co-extruded films can be prepared by sequentially extruding one or more raw materials onto another pre-made film during the film processing, or by bonding different types of pre-made films together.

[0159] In some cases, the first encapsulation layer and the second encapsulation layer still have a boundary line before lamination. After lamination, the photovoltaic module will no longer have the concept of a first encapsulation layer and a second encapsulation layer. That is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0160] In some embodiments, the cover plate 42 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate 42 facing the encapsulating film 41 can be an uneven surface or a textured surface containing multiple raised structures, thereby increasing the utilization rate of incident light. The cover plate 42 may include a first cover plate 421 and a second cover plate 422, the first cover plate 421 being opposite to the first encapsulation layer, and the second cover plate 422 being opposite to the second encapsulation layer.

[0161] refer to Figure 1 and Figure 8 In the photovoltaic module provided in this application, the passivation layer 13 of the back contact cell 40 includes an interface passivation portion 131 and a third doped portion 132. The interface passivation portion 131, located between the first doped portion 11 and the second doped portion 12, can reduce the leakage current between the first doped portion 11 and the second doped portion 12, thereby improving the performance of the back contact cell 40 and thus the performance of the photovoltaic module. The interface passivation portion 131, located between the second doped portion 12 and the substrate 10, can passivate the substrate 10, which also helps to improve the performance of the back contact cell 40 and thus the performance of the photovoltaic module. Furthermore, the third doped portion 132 can improve the efficiency of the second electrode 15 in collecting charge carriers, which also helps to improve the performance of the back contact cell 40 and thus the performance of the photovoltaic module.

[0162] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A back-contact battery, characterized in that, include: A substrate having a first region and a second region, and a third region located between the first region and the second region; A first doped portion, wherein the first doped portion is located in the first region and the third region; The second doped portion is located in the second region and the third region, and the second doped portion and the first doped portion are located on the same side of the substrate; A passivation layer is located in the second region and the third region. The passivation layer includes an interface passivation portion and a third doped portion. The interface passivation portion is located between the substrate and the second doped portion, and between the second doped portion and the first doped portion. The third doped portion is located between the interface passivation portion and the second doped portion and is spaced apart from the first doped portion. The dopant element in the third doped portion has the same conductivity type as the dopant element in the second doped portion. The thickness of the interface passivation portion located between the third doped portion and the substrate is a first thickness, and the ratio of the thickness of the third doped portion to the first thickness is 1 to 15. Along a first direction, the ratio of the length of the third doped portion to the length of the second doped portion is 0.06 to 0.

7. The first direction is defined as the direction in which the first region and the second region are alternately distributed. The first electrode is electrically connected to the first doped portion; The second electrode is electrically connected to the second doped portion.

2. The back contact battery according to claim 1, characterized in that, The interface passivation portion includes a first sub-portion and a second sub-portion located on both sides of the first sub-portion, wherein the first sub-portion is located between the third doped portion and the substrate; and the thickness of the first sub-portion is less than the thickness of the second sub-portion.

3. The back contact battery according to claim 2, characterized in that, The thickness of the first sub-part is 1nm to 4nm; the thickness of the second sub-part is 7nm to 20nm.

4. The back contact battery according to claim 1, characterized in that, The second doped portion includes: The first doped sub-section is located on the surface of the third doped section opposite to the substrate; The second doped sub-section is adjacent to the first doped sub-section; Wherein, the crystallinity of the first doped sub-part is greater than that of the second doped sub-part, and / or, the grain size of the first doped sub-part is greater than that of the second doped sub-part.

5. The back contact battery according to claim 4, characterized in that, The crystallinity of the first doped sub-part is 20%~80%; the crystallinity of the second doped sub-part is 0%~10%.

6. The back contact battery according to claim 4, characterized in that, The grain size of the first doped sub-part is 3nm to 200nm; the grain size of the second doped sub-part is less than or equal to 1nm.

7. The back contact battery according to claim 1, characterized in that, The second doped portion includes: The first doped sub-section is located on the surface of the third doped section opposite to the substrate; The second doped sub-section is adjacent to the first doped sub-section; Wherein, the doping concentration of the doping element in the first doped sub-part is greater than the doping concentration of the doping element in the second doped sub-part.

8. The back contact battery according to claim 1, characterized in that, The thickness of the third doped portion is 4nm to 15nm; the thickness of the interface passivation portion located between the third doped portion and the substrate is a first thickness, which is 1nm to 4nm.

9. The back contact battery according to claim 1, characterized in that, The doping concentration of the dopant element in the third doped part is 5E17 atoms / cm³. 3 ~5E19atoms / cm 3 .

10. A method for preparing a back-contact battery, characterized in that, include: A substrate is obtained, the substrate having a first region and a second region, and a third region located between the first region and the second region; A first doped portion is formed, the first doped portion being located in the first region and the third region; An initial passivation layer is formed, wherein the initial passivation layer and the first doped portion are located on the same side of the substrate, and the initial passivation layer is located on the surface of the first doped portion in the second region and the third region; An initial doped portion is formed, the initial doped portion being located on the surface of the initial passivation layer in the second region and the third region; A doping process is performed to transform the initial doped portion into a second doped portion, and to transform the initial passivation layer, which is a portion of the thickness separated from the first doped portion, into a third doped portion, with the remaining portion of the initial passivation layer being an interface passivation portion; wherein, the doping elements in the third doped portion have the same conductivity type as the doping elements in the second doped portion; the thickness of the interface passivation portion located between the third doped portion and the substrate is a first thickness, and the ratio of the thickness of the third doped portion to the first thickness is 1 to 15; along a first direction, the ratio of the length of the third doped portion to the length of the second doped portion is 0.06 to 0.7, and the first direction is defined as the direction in which the first region and the second region are alternately distributed; A first electrode and a second electrode are formed, wherein the first electrode is electrically connected to the first doped portion, and the second electrode is electrically connected to the second doped portion.

11. The method for preparing a back contact battery according to claim 10, characterized in that, The doping process includes laser processing.

12. The method for preparing a back contact battery according to claim 11, characterized in that, The wavelength of the laser treatment is 325nm~532nm, and the energy density of the laser treatment is 150mJ / cm². 2 ~5000mJ / cm 2 .

13. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple back contact batteries as described in any one of claims 1 to 9, or by connecting back contact batteries prepared by the method of preparing a back contact battery as described in any one of claims 10 to 12. An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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