Back contact cell and method of manufacturing the same, stacked cell, photovoltaic module

Abstract

This disclosure relates to the photovoltaic field, providing a back contact cell and its manufacturing method, a tandem cell, and a photovoltaic module. The manufacturing method of the back contact cell includes: providing a substrate having a first region and a second region alternately distributed along a first direction; forming an initial passivation layer on the first region and the second region; removing the initial passivation layer located in the second region, leaving the initial passivation layer located in the first region as a passivation layer; performing an alkaline treatment on the surface of the substrate located in the second region using an alkaline solution; and performing an acidic treatment on the surface of the substrate located in the second region using an acidic solution, which at least helps to improve the yield and photoelectric conversion efficiency of the formed back contact cell.

Description

Technical Field

[0001] This disclosure relates to the photovoltaic field, and in particular to a back contact battery and its manufacturing method, a tandem battery, and a photovoltaic module. Background Technology

[0002] A photovoltaic cell is a device that converts solar energy into electrical energy. Photovoltaic cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thus facilitating the efficient use of electrical energy.

[0003] Current photovoltaic cells mainly include BC cells (Back Contact cells), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and real cell) cells, and heterojunction cells (Heterojunction with Intrinsic Thin-film, abbreviated as HIT or HJT).

[0004] However, the photoelectric conversion efficiency of current photovoltaic cells still needs to be improved. Summary of the Invention

[0005] This disclosure provides a back contact cell and its manufacturing method, a tandem cell, and a photovoltaic module, which at least helps to improve the yield and photoelectric conversion efficiency of the formed back contact cell.

[0006] This disclosure provides a method for manufacturing a back contact battery, comprising: providing a substrate having alternating first and second regions; forming an initial passivation layer on the first and second regions; ablating the initial passivation layer located in the second region using a first laser, leaving the initial passivation layer remaining in the first region as a passivation layer; performing an alkaline treatment on the surface of the substrate located in the second region using an alkaline solution; and performing an acidic treatment on the surface of the substrate located in the second region using an acidic solution.

[0007] Optionally, after the alkaline treatment and before the acidic treatment, the method for manufacturing the back contact battery further includes rinsing the surface of the substrate located in the second region.

[0008] Optionally, during the process of ablating the initial passivation layer with the first laser, the first laser carries a dopant source, and the first laser is used to cause the dopant element in the dopant source to diffuse into the substrate, so that a portion of the substrate located in the second region is transformed into a doped portion; wherein, the alkaline treatment and the acidic treatment are performed on the doped portion.

[0009] Optionally, the energy density of the first laser is E1, where E1 is expressed in J / cm². 2 The alkaline treatment duration is T, where T is in minutes; and the product of E1 and T is 0.15 to 0.75.

[0010] Optional, 0.5J / cm 2 ≤E1≤2.5J / cm 2 ; and / or, 5s≤T≤25s.

[0011] Optionally, the mass fraction of the alkaline solution is 0.5% to 5%; and / or, the treatment temperature of the alkaline treatment is 20°C to 40°C.

[0012] Optionally, after the acid treatment, the manufacturing method of the back contact battery further includes: forming an initial second doped conductive portion on the side of the passivation layer away from the substrate; annealing the initial second doped conductive portion with a second laser to transform the initial second doped conductive portion into a second doped conductive portion, wherein the energy density of the second laser is less than the energy density of the first laser, and the crystallinity of the second doped conductive portion is higher than that of the initial second doped conductive portion.

[0013] Optionally, the step of forming the initial passivation layer includes: forming an initial first doped conductive portion on the first region and the second region; in the step of forming the passivation layer, the initial first doped conductive portion remaining in the first region is a first doped conductive portion; the step of forming the initial second doped conductive portion includes: growing the initial second doped conductive portion in situ on the side of the first doped conductive portion away from the substrate; wherein the first doped conductive portion and the initial second doped conductive portion are doped with the same type of doping element, the doping concentration of the doping element in the first doped conductive portion is a first concentration, the doping concentration of the doping element in the initial second doped conductive portion is a second concentration, the second concentration is greater than the first concentration; and / or, the crystallinity of the second doped conductive portion is higher than the crystallinity of the first doped conductive portion.

[0014] Optionally, in the step of ablating the initial passivation layer located in the second region with the first laser, the edge of the remaining initial passivation layer located in the first region is modified so that the connection between the side of the passivation layer near the second region and the top surface of the passivation layer away from the substrate is an arc surface.

[0015] This disclosure also provides a back contact battery formed by the manufacturing method of the back contact battery described in any of the preceding claims, the back contact battery comprising: a substrate having alternating first and second regions; a passivation layer located in the first region; and the surface of the substrate located in the second region having undergone an alkaline treatment and an acidic treatment in sequence.

[0016] Optionally, the junction between the side of the passivation layer near the second region and the top surface of the passivation layer away from the substrate is an arc surface; and / or, the substrate located in the second region includes a doped portion, the doped portion being located on the side of the substrate near the passivation layer.

[0017] Optionally, the back contact battery further includes: a second doped conductive portion located on the side of the passivation layer away from the substrate; a dielectric layer located on the surface jointly formed by the second doped conductive portion and the substrate located in the second region; a first electrode embedded in the dielectric layer located in the first region and electrically connected to the second doped conductive portion; and a second electrode embedded in the dielectric layer located in the second region and electrically connected to the substrate.

[0018] This disclosure also provides a stacked battery, comprising: a bottom battery, which is a back contact battery formed by the manufacturing method of the back contact battery described in any of the preceding claims, or a back contact battery described in any of the preceding claims; and a perovskite battery, which is located on one side of the bottom battery.

[0019] This disclosure also provides a photovoltaic module, comprising: a battery string, which is formed by connecting a plurality of back-contact batteries formed by the manufacturing method of the back-contact batteries as described in any of the above claims, or by connecting a plurality of back-contact batteries as described in any of the above claims, or by connecting a plurality of stacked batteries as described in the above claims; 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 battery string.

[0020] The technical solution provided in this disclosure has at least the following advantages: First, an alkaline solution is applied to the second region to remove damage and prevent the corners of the passivation layer near the second region from being too sharp and easily damaged, thus improving the structural stability of the back contact cell and facilitating the fabrication of subsequent layers. Next, an acidic solution is applied to the second region to remove surface oxide residues and create a clean surface. This combination of alkaline and acidic treatments significantly reduces the surface defect state density of the second region while forming a passivation layer that meets requirements. This reduces carrier recombination on the surface of the second region, and improves the contact performance between the second region and other layers during subsequent layer formation, ultimately enhancing the yield and photoelectric conversion efficiency of the resulting back contact cell. Attached Figure Description

[0021] 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 disclosure or 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 disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A process flow diagram of a method for manufacturing a back contact battery according to an embodiment of this disclosure; Figure 2 This is a partial cross-sectional view of the structure after the initial passivation layer is formed in a method for manufacturing a back contact battery according to an embodiment of this disclosure. Figure 3 This is a partial cross-sectional view of the structure after the passivation layer is formed in a method for manufacturing a back contact battery according to an embodiment of this disclosure. Figure 4 This is a partial cross-sectional view of the structure after the doped portion is formed in a method for manufacturing a back contact battery according to an embodiment of the present disclosure. Figure 5 This is a partial cross-sectional view of the structure after the initial second doped conductive portion is formed in a method for manufacturing a back contact battery according to an embodiment of the present disclosure. Figure 6 This is a partial cross-sectional view of the structure after the formation of the second doped conductive portion in a method for manufacturing a back contact battery according to an embodiment of the present disclosure. Figure 7 This is a schematic diagram of another partial cross-sectional structure after the initial passivation layer is formed in the manufacturing method of the back contact battery provided in an embodiment of the present disclosure; Figure 8 This is a schematic diagram of another partial cross-sectional structure after the passivation layer is formed in the manufacturing method of the back contact battery provided in an embodiment of the present disclosure; Figure 9 This is a schematic diagram of another partial cross-sectional structure after the initial second doped conductive portion is formed in the manufacturing method of the back contact battery provided in an embodiment of the present disclosure. Figure 10 This is a partial cross-sectional view of the structure after the electrodes are formed in a method for manufacturing a back contact battery according to an embodiment of the present disclosure. Figure 11 This is a schematic diagram of another partial cross-sectional structure after the electrodes are formed in a method for manufacturing a back contact battery according to an embodiment of the present disclosure. Figure 12 A partial cross-sectional structural diagram of a stacked battery provided in yet another embodiment of this disclosure; Figure 13 A partial three-dimensional structural diagram of a cell string in a photovoltaic module provided in yet another embodiment of this disclosure; Figure 14 This is a partial cross-sectional structural diagram of a photovoltaic module provided in yet another embodiment of the present disclosure.

[0023] Explanation of reference numerals in the attached figures: 100. Substrate; 110. First region; 120. Second region; 101. Initial passivation layer; 111. Passivation layer; 111a. Side surface; 111b. Top surface; 111c. Curved surface; 102. Doped portion; 103. Initial second doped conductive portion; 113. Second doped conductive portion; 104. Initial first doped conductive portion; 114. First doped conductive portion; 105. Dielectric layer; 106. First electrode; 116. Second electrode; 107. Bottom cell; 117. Perovskite cell; 108. Initial tunneling layer; 118. Tunneling layer; 109. Front surface field structure; 40. Back contact cell; 41. Encapsulating film; 42. Cover plate; 43. Solder ribbon. Detailed Implementation

[0024] As can be seen from the background technology, the photoelectric conversion efficiency of photovoltaic cells still needs to be improved.

[0025] Analysis revealed that back-contact solar cells, by moving all electrodes to the back of the cell, eliminate the light-shielding loss of the front electrodes, representing a crucial technological approach to achieving the theoretical efficiency limit of photovoltaic cells. A typical BC cell structure includes a front surface field, an interdigitated emitter on the back surface, and a base region.

[0026] However, existing BC cell manufacturing processes typically involve complex steps such as masking, photolithography, doping, and isolation. While these processes can produce cells with market-compliant efficiencies, they generally suffer from lengthy process flows, poor compatibility between processes, narrow process windows, and silicon wafer damage or performance degradation due to repeated high-temperature or high-energy processes. For example, improper sequence of laser doping processes may damage existing passivation layers; mismatched parameters in chemical processing steps may lead to uneven surface properties of the film, affecting subsequent metallization contacts.

[0027] Therefore, there is an urgent need for a manufacturing method for back contact batteries that features high integration, coordinated optimization of each step, and high process tolerance, in order to simplify the manufacturing process, reduce manufacturing costs, and steadily improve the performance of the resulting batteries.

[0028] This disclosure provides a back-contact battery and its manufacturing method, a tandem battery, and a photovoltaic module. In the manufacturing method of the back-contact battery, an alkaline solution is first used to treat the second region, which helps remove damage to the second region and prevents the corners of the passivation layer near the second region from being too sharp and easily damaged, thereby improving the structural stability of the back-contact battery and facilitating the preparation of subsequent film layers. Furthermore, an acidic solution is used to treat the second region, which helps remove surface oxidation residues and forms a clean second region. Thus, the combination of alkaline and acidic treatments helps to significantly reduce the surface defect state density of the second region while forming a passivation layer that meets the requirements, thereby reducing carrier recombination on the surface of the second region. When other film layers are subsequently formed on the second region, the contact performance between the second region and the film layer can also be improved, thereby comprehensively improving the yield and photoelectric conversion efficiency of the formed back-contact battery.

[0029] In the description of the embodiments of this disclosure, 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 or secondary relationship of the indicated technical features. In the description of the embodiments of this disclosure, "multiple" means two or more (including two), unless otherwise explicitly defined. Similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple pieces" refers to two or more pieces (including two pieces).

[0030] 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 disclosure. 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.

[0031] In the description of the embodiments of this disclosure, 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. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0032] In the description of the embodiments of this disclosure, 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," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of this disclosure and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the embodiments of this disclosure. For example, if the device or element in the illustration is inverted, then the element described as "below," "under," "below," or "bottom" of other elements or features will be oriented "above" or "top" of said other elements or features. Therefore, the term "below" may, depending on the context in which the term is used, encompass both above and below orientations, which will be obvious to those skilled in the art. Materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0033] In the description of the embodiments of this disclosure, unless otherwise expressly specified and limited, 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. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0034] In the description of the embodiments disclosed herein, electrical connection between one component and another 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, so that current flows between the two components when the device is generating electricity. Electrical contact between one component and another means that the two components are not only in contact, but also that current flows between them when the device is generating electricity because both components are made of conductive materials.

[0035] In the description of embodiments of this disclosure, the terms "about," "approximately," "roughly," or "about" for a numerical value referring to a specific parameter include the numerical value, and those skilled in the art will understand that the deviation from the numerical value is within acceptable tolerances of the specific parameter. For example, "about" or "about" for a numerical value may include additional numerical values ​​that are in the range of 90.0% to 110.0% of the numerical value, such as in the range of 95.0% to 105.0%, 97.5% to 102.5%, 99.0% to 101.0%, 99.5% to 100.5%, or 99.9% to 100.1%.

[0036] In the accompanying drawings corresponding to the embodiments of this disclosure, 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. Furthermore, when describing a component as being "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 on a portion of the edge of the entire surface.

[0037] In the description of embodiments of this disclosure, when a component "includes" another component, other components are not excluded unless otherwise stated, and may be further included. When a component (such as a layer, film, region, or substrate) is described as being 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 a component is described as being on the surface of another component, or a component is "directly" on another component, or another component is formed or disposed on the surface of a component, it indicates that there is no intermediate component between the two components. For simplicity and clarity, various components may be drawn at any scale. In the drawings, some components may be omitted for simplicity.

[0038] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "the component" is also intended to include the plural form unless the context clearly indicates otherwise.

[0039] The “components” mentioned above can refer to layers, films, regions, parts, structures, etc.

[0040] The embodiments of this disclosure 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 disclosure to facilitate a better understanding of the embodiments. However, the technical solutions claimed in the embodiments of this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0041] This disclosure provides a method for manufacturing a back contact battery according to an embodiment. The method for manufacturing a back contact battery according to an embodiment of this disclosure will be described in detail below with reference to the accompanying drawings.

[0042] Reference Figures 1 to 3 , Figure 1 This is a process flow diagram of a method for manufacturing a back contact battery according to an embodiment of the present disclosure. Figure 2 This is a partial cross-sectional view of the structure after the initial passivation layer is formed in a method for manufacturing a back contact battery according to an embodiment of this disclosure. Figure 3 This is a partial cross-sectional view of the back contact battery after the passivation layer has been formed, according to an embodiment of the present disclosure. The manufacturing method of the back contact battery includes at least the following steps: S1: Provide a substrate 100, which has an alternating first region 110 and a second region 120.

[0043] S2: An initial passivation layer 101 is formed on the first region 110 and the second region 120.

[0044] S3: Remove the initial passivation layer 101 located in the second region 120, and the remaining initial passivation layer 101 located in the first region 110 becomes the passivation layer 111.

[0045] S4: The surface of the substrate 100 located in the second zone 120 is treated with an alkaline solution.

[0046] S5: The surface of the substrate 100 located in the second zone 120 is acid-treated with an acidic solution.

[0047] It is worth noting that the step of removing the initial passivation layer 101 located in the second region 120 can easily damage the surface of the substrate 100 in the second region 120 that is exposed again, such as causing microcracks on the surface. Based on this, the second region 120 is first treated with an alkaline solution, which helps to remove damage on the second region 120 and avoids the passivation layer 111 near the corner of the second region 120 being too sharp and easily damaged, thereby improving the structural stability of the back contact battery and facilitating the preparation of other films in the future. Furthermore, the second region 120 is then treated with an acidic solution, which helps to remove surface oxidation residues on the second region 120 and form a clean second region 120. Thus, the combination of alkaline and acidic treatments helps to significantly reduce the surface defect state density of the second region 120 while forming a passivation layer 111 that meets the requirements. This reduces the recombination of charge carriers on the surface of the second region 120. When other films are subsequently formed on the second region 120, the contact performance between the second region 120 and the film can also be improved, thereby comprehensively improving the yield and photoelectric conversion efficiency of the formed back contact battery.

[0048] It should be noted that after alkaline treatment with an alkaline solution and before acidic treatment with an acidic solution, a very thin layer of chemical oxide is easily formed naturally on the surface of the exposed second region 120. Specifically, the surface of the second region 120 after alkaline treatment is hydrogen-terminated hydrophobic, but oxygen dissolved in the alkaline solution, as well as oxygen in the air when the semi-finished battery is transferred to the subsequent acidic solution, may rapidly form a native oxide layer of about 1 nm thick on the surface of the second region 120. This is the surface oxide residue on the second region 120 that needs to be removed by the subsequent acidic solution.

[0049] In some cases, for ease of description of the placement of the passivation layer 111 and subsequent films on the substrate 100, the substrate 100 is divided into a first region 110 and a second region 120, meaning the first region 110 and the second region 120 are different areas of the substrate 100. The first region 110 can be considered as the area where the passivation layer 111 is placed on the surface of the substrate 100; the second region 120 can be considered as the substrate 100 requiring alkaline or acidic treatment. In other words, the first region can be considered as the area within the substrate 100 directly opposite the passivation layer 111 along the second direction, or it can be understood as the area where the orthogonal projection of the passivation layer 111 is located on the substrate 100. Therefore, the surface of the first region 110 mentioned herein refers to the surface of the substrate 100 located in the first region 110, and the surface of the second region 120 refers to the surface of the substrate 100 located in the second region 120.

[0050] It should be noted that, Figure 3The diagram only shows three first zones 110 and two second zones 120. In practical applications, the first and second zones can be arranged alternately along the first direction as follows: the base includes multiple first zones and multiple second zones, with one first zone interspersed between two adjacent second zones, and one second zone interspersed between two adjacent first zones.

[0051] The following will describe in more detail a method for manufacturing a back contact battery according to an embodiment of the present disclosure, with reference to the accompanying drawings.

[0052] In some embodiments, continue to refer to Figure 3 After alkaline treatment and before acidic treatment, the manufacturing method of the back contact battery may further include rinsing the surface of the substrate 100 located in the second region 120. This facilitates the rapid removal of residual alkaline solution from the finished battery. When subsequent acidic treatment is performed, it helps reduce the risk of a violent reaction between the acidic solution and the residual alkaline solution, thereby avoiding damage to the surface of the second region 120 and preventing the thermal effects of the acid-base reaction from affecting the second region 120. This improves the surface quality of the second region 120 in multiple ways and prevents dissolved oxygen in the alkaline solution from forming primary oxides on the surface of the second region 120.

[0053] In some cases, the rinsing process can be performed by rinsing the entire finished battery with deionized water.

[0054] In some cases, the rinsing process can last less than 60 seconds, just enough to moisten the surface of the finished battery without drying it out. It should be noted that, without considering the rinsing interval of less than 60 seconds, the alkaline and acidic treatments can be considered as continuous processes. In other words, the interval between alkaline and acidic treatments is controlled to be very short, which also helps to prevent the re-adsorption of contaminants and the uneven growth of native oxides.

[0055] In some embodiments, the mass fraction of the alkaline solution can be 0.5% to 5%, for example, 0.5% to 2%, 2% to 3.5%, or 3.5% to 5%. Optionally, the mass fraction of the alkaline solution can be 0.5%, 1%, 1.5%, 1%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, etc.

[0056] It is worth noting that, reference Figure 3 Compared to conventional alkaline etching or alkaline texturing, the alkaline treatment step involves a very low concentration of alkaline solution. It only removes laser-damaged, heat-affected areas or microcracks in the second region 120. The etching rate on the intact passivation layer 111 is extremely low and has almost no effect, thus not causing damage to the passivation layer 111.

[0057] In some cases, an alkaline solution can be a potassium hydroxide solution, a tetramethylammonium hydroxide solution, or a sodium hydroxide solution. Therefore, the mass fraction of an alkaline solution refers to the mass fraction of at least one of the following: potassium hydroxide solution, tetramethylammonium hydroxide solution, or sodium hydroxide solution.

[0058] Furthermore, following the alkaline treatment with a designed rinsing process to remove residual alkaline solution can also prevent residual metal ions, such as potassium ions, from remaining on the surface of the semi-finished battery. + Or Na + This reduces the risk of performance degradation of the back contact battery caused by metal ions, as it is carried into the subsequent acidic solution and prevents metal ions from contaminating other processes.

[0059] In some embodiments, the acidic solution may be a mixed solution comprising hydrofluoric acid and ozone. Wherein, reference... Figure 3 Hydrofluoric acid helps remove the native oxides formed on the surface of the second zone 120 in the previous process, exposing a clean second zone 120; ozone helps to regenerate an ultra-thin, dense chemical oxide layer with high passivation quality on the basis of the clean second zone 120, so as to improve the passivation effect on the substrate 100.

[0060] In some cases, the process of treating the surface of the substrate 100 located in the second region 120 can be as follows: first, the surface of the substrate 100 located in the second region 120 is treated with an alkaline solution; the surface of the substrate 100 located in the second region 120 is rinsed; the semi-finished battery is transferred to a subsequent acidic solution, where oxygen in the air forms native oxide on the surface of the second region 120; then, the native oxide formed on the surface of the second region 120 is removed with an acidic solution, and new ultrathin, dense chemical oxides with high passivation quality are grown.

[0061] In some embodiments, the alkaline treatment temperature can be 20℃~40℃, for example, 20℃~25℃, 25℃~30℃, 30℃~35℃, or 35℃~40℃. Optionally, the alkaline treatment temperature can be 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, 35℃, 36℃, 37℃, 38℃, 39℃, or 40℃, etc. Thus, refer to... Figure 3 The design of a lower processing temperature can also avoid the alkaline treatment causing etching damage to the passivation layer 111.

[0062] In some embodiments, in conjunction with reference Figure 2 and Figure 3The step of removing the initial passivation layer 101 located in the second region 120 may include: ablating the initial passivation layer 101 located in the second region 120 using a first laser. This facilitates the selective removal of the initial passivation layer 101 located in the second region 120, thereby rapidly and efficiently forming the passivation layer 111 and improving the accuracy of the area where the passivation layer 111 is located.

[0063] It is worth noting that the first laser is prone to causing laser damage and certain thermal effects on the surface of the second region 120 that is exposed again. Alkaline treatment helps to remove this laser damage, and the high-quality passivation chemical oxide formed in the acid treatment helps to passivate and repair the thermal effects on the surface of the second region 120, thereby effectively reducing the defect state density on the surface of the second region 120, which in turn facilitates the formation of a high-quality passivation structure on the second region 120.

[0064] In some cases, in conjunction with references Figure 2 and Figure 4 During the process of ablation of the initial passivation layer 101 by the first laser, the first laser carries a dopant source and uses the first laser to cause the dopant element in the dopant source to diffuse into the substrate 100, so that a portion of the thickness of the substrate 100 located in the second region 120 is transformed into a doped portion 102; wherein, alkaline treatment and acidic treatment are performed on the doped portion 102.

[0065] It should be noted that, Figure 4 This is a partial cross-sectional view of the structure after the doped portion is formed in the manufacturing method of the back contact battery provided in an embodiment of this disclosure; furthermore, to illustrate that the doped portion 102 is transformed from a substrate 100 of a certain thickness, Figure 4 The region where the doped portion 102 is located is roughly delineated within the substrate 100 by dashed lines. The formation steps of other films will then be explained using the formation of the doped portion 102 in the second region 120 as an example.

[0066] In this way, the first laser can be used to both pattern the initial passivation layer 101 to form the passivation layer 111 and to dope the second region 120 to form the doped portion 102, thus completing the fabrication of the passivation layer 111 and the doped portion 102 in the same step. In other words, in the back contact battery manufacturing method provided in one embodiment of this disclosure, the formation of the passivation layer 111 and the doped portion 102 can be achieved using industrially mature laser equipment and deposition equipment, avoiding the use of expensive photolithography or complex multiple masking techniques, making the manufacturing process simpler, which is conducive to large-scale production and reducing manufacturing costs. The doped portion 102 helps to passivate the surface of the second region 120 and improve the collection efficiency of charge carriers in the second region 120.

[0067] It is worth noting that the passivation layer 111 is an additional film layer formed on the surface of the substrate 100, and the doped portion 102 is transformed from a portion of the thickness of the substrate 100. Therefore, there is a height difference between the passivation layer 111 and the doped portion 102 along the second direction Y, or in other words, a step is formed between the passivation layer 111 and the doped portion 102.

[0068] Wherein, the second direction Y is the thickness direction of the substrate 100, and the second direction Y intersects with the first direction X.

[0069] It is worth emphasizing that the intersection of the first direction X and the second direction Y includes the following situations: the first direction X and the second direction Y are orthogonal, or the angle formed by the first direction X and the second direction Y is an obtuse angle, or the angle formed by the first direction X and the second direction Y is an acute angle.

[0070] In some examples, the angle between the first direction X and the second direction Y can be 10° to 90°, such as 10°, 20°, 45°, 55°, 70°, 82°, or 90°. In some specific examples, the angle between the first direction X and the second direction Y can be 45° to 90°, such as 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, or 90°.

[0071] In some examples, the method of making the first laser carry the dopant source may include: when emitting the laser, introducing a gas containing the dopant source near the laser head to complete the doping of a portion of the thickness of the substrate 100 located in the second region 120; or, when emitting the laser, controlling the laser to knock elements in a solid film containing the dopant source onto the second region 120 to complete the doping of a portion of the thickness of the substrate 100 located in the second region 120.

[0072] Thus, the first laser rapidly melts the surface of the exposed second region 120, while simultaneously pushing the dopant element from the dopant source into the molten region of the second region 120, which is then recrystallized to form the doped portion 102.

[0073] In some examples, the doping element in at least a portion of the passivation layer 111 is of a different type than the doping element in the doped portion 102.

[0074] In one example, at least a portion of the passivation layer 111 is doped with an N-type dopant, while the doped portion 102 is doped with a P-type dopant. For instance, the passivation layer 111 is doped with phosphorus, and the doped portion 102 can be considered as a boron laser doped portion.

[0075] In another example, at least a portion of the passivation layer 111 is doped with a p-type dopant, while the doped portion 102 is doped with an n-type dopant. For instance, the passivation layer 111 is doped with boron, and the doped portion 102 can be considered a phosphorus laser doped portion.

[0076] The N-type dopant can be at least one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As); the P-type dopant can be at least one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or gallium (In).

[0077] In some cases, the energy density of the first laser is E1, where the unit of E1 is J / cm². 2 The alkaline treatment duration is T, where T is in minutes; the product of E1 and T is 0.15 to 0.75.

[0078] It is worth noting that the energy density E1 of the first laser not only affects the precision of the area where the passivation layer 111 is formed, i.e., the precision of the first region 110, but also the degree of laser damage to the surface of the second region 120 and the size of the heat-affected zone on the substrate 100. The duration T of the alkaline treatment not only affects the degree of laser damage removal from the second region 120, but also the corrosion risk to the passivation layer 111. Furthermore, the energy density E1 of the first laser reflects the rate of laser damage generation, while the treatment duration T of the alkaline treatment reflects the rate of laser damage removal. Laser damage is generated relatively rapidly, almost instantaneously, while the corrosion of laser damage by the alkaline treatment is continuous. Therefore, matching the total amounts of both ensures that the laser damage is removed by the substrate.

[0079] The product of E1 and T represents the degree of matching between the "total laser damage" and the "chemical removal capability". Furthermore, the thickness of the damaged layer generated by the first laser is approximately α × E1 (α is the material absorption coefficient), and the thickness removed by chemical corrosion under alkaline treatment is approximately β × T (β is the corrosion rate). Multiplying these two values, α × β is approximately a constant under certain conditions. Therefore, when the product of E1 and T is within a preset range, it indicates that the laser damage generated by the first laser is just removed by the alkaline treatment.

[0080] Based on this, the product of E1 and T is designed to be between 0.15 and 0.75, ensuring that the degree of laser damage caused by the first laser to the surface of the second region 120 matches the degree of laser damage removal by the alkaline treatment. This helps to ensure that the laser damage on the surface of the second region 120 is effectively removed and avoids corrosion of the passivation layer 111, thereby ensuring effective repair of laser damage and maintenance of pattern accuracy. It is worth emphasizing that the relevant process parameters of the first laser and the alkaline treatment support and synergize with each other, thereby widening the process window and improving production yield.

[0081] In some examples, the product of E1 and T can be 0.15~0.3, 0.3~0.45, 0.45~0.6, or 0.6~0.75. Alternatively, the product of E1 and T can be 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, or 0.75, etc.

[0082] In some examples, the pulse width of the first laser can be from 1 nanosecond to 50 nanoseconds, for example, it can be from 1 nanosecond to 10 nanoseconds, 10 nanoseconds to 20 nanoseconds, 20 nanoseconds to 30 nanoseconds, 30 nanoseconds to 40 nanoseconds, or 40 nanoseconds to 50 nanoseconds. Optionally, the pulse width of the first laser can be 1 nanosecond, 5 nanoseconds, 10 nanoseconds, 15 nanoseconds, 20 nanoseconds, 25 nanoseconds, 30 nanoseconds, 35 nanoseconds, 40 nanoseconds, 45 nanoseconds, or 50 nanoseconds, etc.

[0083] In some examples, the wavelength of the first laser can be 532nm or 1064nm, etc.

[0084] In some examples, 0.5 J / cm 2 ≤E1≤2.5J / cm 2 For example, 0.5 J / cm 2 ≤E1≤1J / cm 2 1J / cm 2 ≤E1≤1.5J / cm 2 1.5J / cm 2 ≤E1≤2J / cm 2 or 2J / cm 2 ≤E1≤2.5J / cm 2 Optionally, the energy density of the first laser, E1, can be 0.5 J / cm². 2 0.6J / cm 2 0.7J / cm 2 0.8J / cm 2 0.9J / cm 2 1J / cm 2 1.1 J / cm2 1.2J / cm 2 1.3J / cm 2 1.4J / cm 2 1.5J / cm 2 1.6J / cm 2 1.7J / cm 2 1.8J / cm 2 1.9J / cm 2 2J / cm 2 2.1 J / cm 2 2.2J / cm 2 2.3J / cm 2 2.4J / cm 2 Or 2.5J / cm 2 wait.

[0085] If the energy density E1 of the first laser is less than 0.5 J / cm² 2 The low removal efficiency of the initial passivation layer 101 leads to a low fabrication efficiency of the passivation layer 111; if the energy density E1 of the first laser is greater than 2.5 J / cm²... 2 This can easily cause significant laser damage to the surface of the second region 120. Therefore, a laser strength of 0.5 J / cm² is designed. 2 ≤E1≤2.5J / cm 2 This is beneficial to ensure high efficiency in the preparation of the passivation layer 111 while minimizing laser damage to the surface of the second region 120 caused by the first laser.

[0086] In some examples, 5s ≤ T ≤ 25s, for example, 5s ≤ T ≤ 10s, 10s ≤ T ≤ 15s, 15s ≤ T ≤ 20s, or 20s ≤ T ≤ 25s. Optionally, the treatment time for alkaline treatment, i.e., T, can be 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s, 20s, 21s, 22s, 23s, 24s, or 25s, etc.

[0087] If the alkaline treatment time T is less than 5s, the laser damage to the second region 120 may not be completely removed; if the alkaline treatment time T is greater than 25s, the risk of corrosion of the passivation layer 111 may increase. Therefore, designing a time of 5s≤T≤25s is beneficial to ensure that the laser damage to the second region 120 is completely removed while minimizing the risk of corrosion of the passivation layer 111, thereby ensuring the yield of the final back contact battery.

[0088] In some embodiments, the method for manufacturing the back contact battery after acid treatment may further include: referencing Figure 5 , Figure 5 This is a partial cross-sectional view of a back contact battery manufacturing method according to an embodiment of the present disclosure, showing the initial second doped conductive portion 103 formed on the side of the passivation layer 111 away from the substrate 100; in conjunction with reference to... Figure 5 and Figure 6 , Figure 6 This is a partial cross-sectional structural diagram of a back contact battery manufacturing method provided in an embodiment of the present disclosure after the formation of the second doped conductive portion. The initial second doped conductive portion 103 is annealed using a second laser to transform the initial second doped conductive portion 103 into the second doped conductive portion 113. The energy density of the second laser is less than that of the first laser, and the crystallinity of the second doped conductive portion 113 is higher than that of the initial second doped conductive portion 103.

[0089] This allows for the formation of a second doped conductive portion 113 with a higher crystallinity using the second laser, thereby enhancing the passivation effect of the second doped conductive portion 113 on the first region 110 and reducing carrier recombination on the surface of the first region 110. Furthermore, the high crystallinity of the second doped conductive portion 113 results in high conductivity, which helps improve the collection efficiency of carriers in the substrate 100. It is worth emphasizing that after forming the passivation layer 111, the surface of the second region 120 is pre-processed to prepare it into the desired form, for example, by pre-forming the doped portion 102 before forming the second doped conductive portion 113 on the passivation layer 111. This helps avoid the formation of the second doped conductive portion 113 affecting the surface of the second region 120, thus ensuring that the second region 120 remains unaffected while improving the passivation effect and carrier collection efficiency of the first region 110.

[0090] Furthermore, designing the energy density of the second laser to be lower than that of the first laser is beneficial in increasing the crystallinity of the second doped conductive portion 113 without damaging the passivation layer 111 or the first region 110 located below the second doped conductive portion 113. In other words, the second laser has almost no impact on the passivation layer 111. Moreover, the second laser improves the conductivity of the second doped conductive portion 113 without sacrificing the passivation quality of the passivation layer 111, thereby simultaneously improving the open-circuit voltage and fill factor of the formed back contact cell. It is worth emphasizing that the energy density of the second laser and the energy density of the first laser support and synergize with each other, thereby improving the production yield.

[0091] In some cases, the ratio of the energy density of the second laser to that of the first laser can be less than or equal to 0.6. For example, the ratio can be 0.5~0.6, 0.4~0.5, 0.3~0.4, 0.2~0.3, or 0.1~0.2. Optionally, the ratio can be 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0... 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, or 0.59, etc.

[0092] Thus, designing the energy density of the second laser to be less than or equal to 0.6 with the energy density of the first laser helps to ensure that the second laser is only used to improve the crystallinity of the initial second doped conductive portion 103, and that the second laser will not penetrate the initial second doped conductive portion 103 to damage the passivation layer 111 and the first region 110.

[0093] In some cases, the wavelength of the second laser can be shorter than that of the first laser.

[0094] In some examples, the wavelength of the second laser can be 355 nm.

[0095] In some examples, the energy density of the second laser can be 0.3 J / cm². 2 ~1J / cm 2 For example, it can be 0.3 J / cm 2 ~0.5J / cm 2 0.5J / cm 2 ~0.7J / cm 2 Or 0.7J / cm 2 ~1J / cm 2 Optionally, the energy density of the second laser can be 0.3 J / cm². 2 0.35J / cm 2 0.4J / cm 2 0.45J / cm 2 0.5J / cm 2 0.55J / cm 2 0.6J / cm 20.65J / cm 2 0.7J / cm 2 0.75J / cm 2 0.8J / cm 2 0.85J / cm 2 0.9J / cm 2 0.95J / cm 2 / or 1J / cm 2 wait.

[0096] In some cases, refer to Figure 7 , Figure 7 This is a schematic diagram of another partial cross-sectional structure after the initial passivation layer is formed in the manufacturing method of the back contact battery provided in an embodiment of the present disclosure. The step of forming the initial passivation layer 101 may include: forming an initial first doped conductive portion 104 on the first region 110 and the second region 120.

[0097] Reference Figure 7 and Figure 8 , Figure 8 This is a schematic diagram of another partial cross-sectional structure after the passivation layer is formed in the manufacturing method of the back contact battery provided in an embodiment of the present disclosure. In the step of forming the passivation layer 111, the remaining initial first doped conductive portion 104 located in the first region 110 is the first doped conductive portion 114.

[0098] Reference Figure 8 and Figure 9 , Figure 9 This is a schematic diagram of another partial cross-sectional structure after forming an initial second doped conductive portion in a method for manufacturing a back contact battery according to an embodiment of the present disclosure. The step of forming the initial second doped conductive portion 103 may include: growing the initial second doped conductive portion 103 in situ on the side of the first doped conductive portion 114 away from the substrate 100.

[0099] It should be noted that, Figure 8 and Figure 9 The example in which a doped portion 102 is formed in the second region 120 is taken as an example.

[0100] It is worth emphasizing that in-situ growth is only performed in the area of ​​passivation layer 111, i.e., the first region 110. The surface of the second region 120, which has been treated by the first laser, has been exposed. Therefore, in the in-situ growth step, the initial second doped conductive portion 103 will only be formed on the side of the first doped conductive portion 114 away from the substrate 100.

[0101] In some examples, the initial second doped conductive portion 103 can also be grown in situ on the side of the first doped conductive portion 114 away from the substrate 100 using a PECVD process.

[0102] In some examples, reference Figure 7 Before forming the initial first doped conductive portion 104, the step of forming the initial passivation layer 101 may further include: forming an initial tunneling layer 108 on the first region 110 and the second region 120; in conjunction with reference to... Figure 7 and Figure 8 In the step of forming the passivation layer 111, the remaining initial tunneling layer 108 located in the first region 110 is a tunneling layer 118. In other words, the passivation layer 111 includes a tunneling layer 118 and a first doped conductive portion 114 stacked along the second direction Y.

[0103] In addition, in conjunction with reference Figure 9 and Figure 10 The doped conductive structure located in the first region 110 includes a first doped conductive portion 114 and a second doped conductive portion 113 stacked along the second direction Y. Figure 10 This is a partial cross-sectional view of the structure after the electrodes are formed in a manufacturing method of a back contact battery according to an embodiment of the present disclosure. The electrodes include a first electrode 106 and a second electrode 116.

[0104] In some examples, the first doped conductive portion 114 and the initial second doped conductive portion 103 are doped with the same type of doping element. The doping concentration of the doping element in the first doped conductive portion 114 is a first concentration, and the doping concentration of the doping element in the initial second doped conductive portion 103 is a second concentration. The second concentration may be greater than the first concentration.

[0105] It is worth noting that, subsequently, under the action of the second laser, the doping concentration of the doped element in the second doped conductive portion 113 formed based on the initial second doped conductive portion 103 will be greater than or equal to the doping concentration of the doped element in the initial second doped conductive portion 103. Specifically, the second laser helps to further increase the doping concentration of the doped element in the second doped conductive portion 113.

[0106] Thus, the doping concentration of the doped element in the second doped conductive portion 113 is greater than that in the first doped conductive portion 114. This is beneficial for improving the passivation effect on the first region 110 by using the second doped conductive portion 113 with a higher doping concentration, thereby reducing the recombination of charge carriers on the surface of the first region 110. Moreover, the second doped conductive portion 113 with a higher doping concentration has higher conductivity, which helps to improve the collection efficiency of charge carriers in the substrate 100. This helps to improve the conductivity of the second doped conductive portion 113 without sacrificing the passivation quality of the passivation layer 111.

[0107] Furthermore, on the one hand, the first doped conductive portion 114 with a lower doping concentration can closely adhere to the tunneling layer 118, serving as an interface passivation layer to ensure a higher open-circuit voltage for the back contact battery; on the other hand, the second doped conductive portion 113 with a higher doping concentration can improve the conductivity of lateral carrier transport and subsequently enhance the performance of contact with the electrode. Thus, based on the cooperation of the first doped conductive portion 114 and the second doped conductive portion 113, both low-concentration passivation of the first region 110 and high-concentration conductivity of the doped conductive portion located in the first region 110 can be achieved, and the subsequent penetration of the passivation layer 111 by the electrode located in the first region 110 can be prevented.

[0108] In some examples, the crystallinity of the second doped conductive portion 113 may be higher than that of the first doped conductive portion 114.

[0109] It is worth noting that under the action of the second laser, the crystallinity of the second doped conductive portion 113 is higher than that of the initial second doped conductive portion 103. Moreover, the doped conductive structure located on the first region 110 includes the first doped conductive portion 114 and the second doped conductive portion 113. Based on this, it is further ensured that the crystallinity of the second doped conductive portion 113 can be higher than that of the first doped conductive portion 114, which helps to ensure that the crystallinity of the second doped conductive portion 113 in the doped conductive structure is higher, thereby improving the passivation capability of the overall doped conductive structure for the first region 110; moreover, it helps to improve the overall conductivity of the doped conductive structure without sacrificing the passivation quality of the passivation layer 111.

[0110] In some examples, the crystalline state of the second doped conductive portion 113 may include at least one of the following: microcrystalline state (a state that simultaneously has a single crystalline state and an amorphous state, referred to as microcrystalline state), nanocrystalline state, microcrystalline state, or a mixture of nanocrystalline and microcrystalline states, for example, a mixture of nanocrystalline silicon and microcrystalline silicon, which can improve the conductivity of the second doped conductive portion 113; the crystalline state of the first doped conductive portion 114 remains basically amorphous, so as to maximize the passivation effect of the first doped conductive portion 114 on the first region 110.

[0111] In some embodiments, in conjunction with reference Figure 2 and Figure 3 or in conjunction with references Figure 7 and Figure 8 In the step of removing the initial passivation layer 101 located in the second region 120, the edge of the remaining initial passivation layer 101 located in the first region 110 is modified so that the connection between the side surface 111a of the passivation layer 111 near the second region 120 and the top surface 111b of the passivation layer 111 away from the substrate 100 can be an arc surface 111c.

[0112] It is worth noting that, in addition to modifying the corner of the passivation layer 111 near the second region 120 during the subsequent alkaline treatment of the surface of the second region 120, the corner of the passivation layer 111 near the second region 120 can be rounded for the first time by means of a removal process, such as a first laser, during the step of removing the initial passivation layer 101 located in the second region 120. Subsequently, the corner of the passivation layer 111 near the second region 120 can be rounded for the second time by means of alkaline treatment. This helps to further ensure that the corner of the final passivation layer 111 near the second region 120, that is, the connection between the side 111a of the passivation layer 111 near the second region 120 and the top surface 111b of the passivation layer 111 away from the substrate 100, is an arc surface 111c. This improves the structural stability of the back contact battery and facilitates the preparation of other films in the future.

[0113] In some embodiments, reference Figure 10 After forming the second doped conductive portion 113, the method for manufacturing the back contact battery may further include: forming a dielectric layer 105 on the surface jointly formed by the second doped conductive portion 113 and the substrate 100 located in the second region 120; forming a first electrode 106 and a second electrode 116, wherein the first electrode 106 is embedded in the dielectric layer 105 located in the first region 110 and electrically connected to the second doped conductive portion 113, and the second electrode 116 is embedded in the dielectric layer 105 located in the second region 120 and electrically connected to the substrate 100.

[0114] It is worth noting that the dielectric layer 105 can not only serve as a passivation and antireflection layer to improve the absorption and utilization rate of light by the back contact battery, but also isolate the first electrode 106 and the second electrode 116.

[0115] In some cases, a deposition process can be used to form the dielectric layer 105. In some examples, a deposition process can be used to form a film of at least one of silicon nitride, aluminum oxide, or silicon oxynitride on the surface formed by the second doped conductive portion 113 and the substrate 100 located in the second region 120.

[0116] In some examples, the dielectric layer 105 can be a silicon nitride layer or a stacked structure consisting of an aluminum oxide layer and a silicon nitride layer.

[0117] In some cases, the method of forming the first electrode 106 and the second electrode 116 may include: using a third laser to ablate the dielectric layer 105 located in the first region 110 and the second region 120, respectively, to form a first contact hole exposing a portion of the passivation layer 111 or the second doped conductive portion 113, and a second contact hole exposing a portion of the second region 120 or the doped portion 102; and then forming a first electrode 106 that at least fills the first contact hole, and a second electrode 116 that at least fills the second contact hole. Thus, the first electrode 106 achieves ohmic contact with the passivation layer 111 or the second doped conductive portion 113 via the first contact hole, and the second electrode 116 achieves ohmic contact with the second region 120 or the doped portion 102 via the second contact hole.

[0118] In some examples, the parameters of the third laser can be the same as those of the second laser, which helps to avoid damage to the film layer located below the dielectric layer 105 by the third laser.

[0119] In some examples, the first electrode 106 and the second electrode 116 can be formed by physical vapor deposition processes, such as sputtering, or by a combination of physical vapor deposition and electroplating.

[0120] In some examples, both the first electrode 106 and the second electrode 116 can be copper electrodes.

[0121] In some embodiments, in conjunction with reference Figure 7 and Figure 11 , Figure 11 This is a schematic diagram of another partial cross-sectional structure after electrode formation in a method for manufacturing a back contact battery according to an embodiment of the present disclosure. The substrate 100 has a front side and a back side opposite to each other along a first direction X. The back side is used to form an initial passivation layer 101. After forming the initial passivation layer 101, the method for manufacturing the back contact battery may further include: performing a doping treatment on the front side to transform a portion of the thickness of the substrate 100 into a front surface field structure 109; or, additionally forming a front surface field structure 109 on the front side. The front surface field structure and the substrate 100 are doped with different types of doping elements.

[0122] It should be noted that the manufacturing method of the front surface field structure 109 in the manufacturing method of the back contact battery provided in one embodiment of this disclosure is not limited, and can be flexibly selected according to actual needs.

[0123] The following provides a detailed description of a method for manufacturing a back contact battery according to an embodiment of the present disclosure. Examples 1, 1 Comparative Example, and 2 are provided below, exemplarily manufactured according to the method for manufacturing a back contact battery according to an embodiment of the present disclosure.

[0124] Example 1 This embodiment provides a method for manufacturing a back contact battery, the method is as follows: (1) Provide an N-type silicon wafer, and after texturing, use boron diffusion to form a front surface field structure.

[0125] (2) After cleaning the N-type silicon wafer that forms the front surface field structure, a silicon oxide layer of about 2 nm thick is grown on the back side of the N-type silicon wafer by thermal oxidation as a tunneling layer.

[0126] (3) A phosphorus-doped amorphous silicon layer with a thickness of about 10 nm is formed by PECVD process as the first doped conductive part.

[0127] (4) A wavelength of 532 nm, a pulse width of 20 ns, and an energy density of 1.8 J / cm² were used. 2 The laser scans according to a predetermined pattern, ablates the second region 120, and performs boron laser doping on the second region 120 to form a doped part.

[0128] (5) Immediately place the N-type silicon wafer with the doped part into a 2% tetramethylammonium hydroxide solution and treat it at 35°C for 9 seconds (i.e. 0.15 minutes). The product of E1 and T can be the product of 1.8 and 0.15, i.e. 0.27, and its value of 0.27 is in the range of 0.15 to 0.75.

[0129] (6) Then it is transferred to a mixed solution containing hydrofluoric acid and ozone for cleaning.

[0130] (7) A phosphorus-doped amorphous silicon layer with a higher phosphorus doping concentration of about 15 nm is deposited on the side of the first doped conductive part away from the first region using PECVD process as the initial second doped conductive part.

[0131] (8) A wavelength of 355 nm and an energy density of 0.8 J / cm² were used. 2 A laser (satisfying 0.8 < 0.6 × 1.8 = 1.08) is used to scan and anneal the initial second doped conductive part to form the second doped conductive part.

[0132] (9) A silicon nitride film of about 80 nm thick is deposited on the entire back side as a dielectric layer.

[0133] (10) Using a laser with the same parameters as in step (8), open a first contact hole and a second contact hole in the dielectric layer 105 located in the first region 110 and the second region 120, respectively.

[0134] (11) A seed layer is formed by sputtering and a copper electrode is formed by patterned electroplating.

[0135] Tests showed that the average photoelectric conversion efficiency of a batch of back contact batteries formed in Example 1 was approximately 25.2%, the open-circuit voltage exceeded 710mV, the fill factor exceeded 82.5%, and the yield (i.e. the proportion of back contact batteries with a photoelectric conversion efficiency greater than 24.8%) reached 96%.

[0136] Comparative Example 1 This comparative example provides a method for manufacturing a back contact battery, the preparation method of which is as follows: The difference between this comparative example and Example 1 is that steps (5) and (6) are not performed in this comparative example, while the remaining steps are the same as in Example 1.

[0137] Comparative Example 2 This comparative example provides a method for manufacturing a back contact battery, the preparation method of which is as follows: The difference between this comparative example and Example 1 is that the ratio of the laser energy density used in step (8) to the laser energy density used in step (4) in this comparative example is greater than 0.6.

[0138] According to the test, compared with the batch of back contact batteries formed by Example 1, the batch of back contact batteries formed by Comparative Example 1 or Comparative Example 2 had lower open circuit voltage and fill factor. The laser area in step (4) of the EL test pattern had obvious composite defects. The yield (i.e. the proportion of back contact batteries with photoelectric conversion efficiency greater than 24.8%) dropped to below 85%.

[0139] In summary, the manufacturing method of the back contact battery provided in one embodiment of this disclosure has the characteristics of simplified process, good compatibility, minimizing damage to the first region 110, and improving the electrical performance of the back contact battery.

[0140] Another embodiment of this disclosure provides a back contact battery, formed by the manufacturing method of the back contact battery provided in the foregoing embodiment. The back contact battery provided in this other embodiment will be described in detail below with reference to the accompanying drawings. 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 hereafter.

[0141] refer to Figure 3The back contact solar cell includes: a substrate 100 having alternating first regions 110 and second regions 120; a passivation layer 111 located in the first region 110; and the surface of the substrate 100 located in the second region 120 having undergone alkaline and acidic treatments sequentially. It is worth emphasizing that the surface of the substrate 100 located in the second region 120, having undergone alkaline and acidic treatments sequentially, has a low defect state density, which helps reduce carrier recombination on the surface of the second region 120 and improves the contact performance between the second region 120 and the film layer formed on it, thereby comprehensively improving the photoelectric conversion efficiency of the back contact solar cell.

[0142] In some embodiments, reference Figure 3 The junction between the side surface 111a of the passivation layer 111 near the second region 120 and the top surface 111b of the passivation layer 111 away from the substrate 100 can be an arc surface 111c. In this way, the corner of the passivation layer 111 near the second region 120 can be avoided from being too sharp and easily damaged, thereby improving the structural stability of the back contact battery.

[0143] In some embodiments, reference Figure 4 The substrate 100 located in the second region 120 may include a doped portion 102, which is located on the side of the substrate 100 near the passivation layer 111. This helps to passivate the surface of the second region 120 by means of the doped portion 102 and improve the collection efficiency of charge carriers in the second region 120.

[0144] In some embodiments, reference Figure 10 or Figure 11 The back contact battery may further include: a second doped conductive portion 113 located on the side of the passivation layer 111 away from the substrate 100; a dielectric layer 105 located on the surface jointly formed by the second doped conductive portion 113 and the substrate 100 located in the second region 120; a first electrode 106 embedded in the dielectric layer 105 located in the first region 110 and electrically connected to the second doped conductive portion 113; and a second electrode 116 embedded in the dielectric layer 105 located in the second region 120 and electrically connected to the substrate 100.

[0145] Thus, the passivation layer 111 and the second doped conductive portion 113 together passivate the first region 110, thereby helping to further reduce the recombination of charge carriers on the surface of the first region 110. Moreover, the passivation layer 111 and the second doped conductive portion 113 work together to help improve the collection efficiency of charge carriers in the substrate 100.

[0146] In some cases, refer to Figure 10The passivation layer 111 may include a tunneling layer 118 and a first doped conductive portion 114 stacked along the second direction Y. The first doped conductive portion 114 and the second doped conductive portion 113 stacked along the second direction Y in the first region 110 constitute a doped conductive structure.

[0147] In some examples, the crystallinity of the second doped conductive portion 113 may be higher than that of the first doped conductive portion 114.

[0148] In some examples, the crystalline state of the second doped conductive portion 113 may include at least one of the following: microcrystalline state (a state that simultaneously has a single crystalline state and an amorphous state, referred to as microcrystalline state), nanocrystalline state, microcrystalline state, or a mixture of nanocrystalline and microcrystalline states, for example, a mixture of nanocrystalline silicon and microcrystalline silicon; the crystalline state of the first doped conductive portion 114 remains substantially amorphous.

[0149] In some examples, the first doped conductive portion 114 and the second doped conductive portion 113 are doped with the same type of doping element, and the doping concentration of the doping element in the first doped conductive portion 114 is lower than the doping concentration in the second doped conductive portion 113.

[0150] In some cases, refer to Figure 11 The substrate 100 has a front side and a back side opposite to each other along a first direction X; the back contact cell may further include a front surface field structure 109 located on the front side. The front surface field structure and the substrate 100 are doped with different types of doping elements.

[0151] Another embodiment of this disclosure provides a stacked battery, which includes a back contact battery formed by the manufacturing method of the back contact battery provided in the foregoing embodiments, or the back contact battery provided in the foregoing embodiments. The stacked battery provided in another embodiment of this disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that the 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 hereafter.

[0152] refer to Figure 12 , Figure 12 This is a partial cross-sectional structural diagram of a tandem solar cell provided in another embodiment of the present disclosure. The tandem solar cell includes: a bottom cell 107, which is a back contact cell formed by the manufacturing method of the back contact cell of any of the above claims, or is a back contact cell of any of the above claims; and a perovskite cell 117, which is located on one side of the bottom cell 107.

[0153] In some embodiments, the perovskite solar cell 117 may include: a first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an antireflection layer stacked together. The first transport layer is directly opposite the base cell 107.

[0154] In some examples, the first transport layer can be either an electron transport layer or a hole transport layer, and the second transport layer can be either an electron transport layer or a hole transport layer.

[0155] In some embodiments, the bandgap width of the perovskite cell 117 is wider than that of the bottom cell 107. Therefore, stacking the perovskite cell 117 on top of the bottom cell 107 can give the stacked cell a wider spectral response range, thereby maximizing the utilization of solar energy and improving the efficiency of the stacked cell.

[0156] In some embodiments, the stacked cell may further include an intermediate connecting layer (not shown in the figure), which connects the bottom cell 107 and the perovskite cell 117.

[0157] In some cases, the intermediate connecting layer is typically 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 photoelectric properties, high photon transmittance, and high conductivity, thereby enabling the perovskite solar cell 117 and the bottom cell 107 to maintain good ohmic contact.

[0158] In other cases, the electrodes in the back contact cell, which serves as the bottom cell 107, can also be used as an intermediate connecting layer to achieve electrical connection with the perovskite cell 117.

[0159] It should be noted that the electrical connection between the two actually means that both are made of conductive materials and are directly connected or connected through other conductive materials. Therefore, when the tandem battery is generating electricity, there is an electrical connection between the two.

[0160] Another embodiment of this disclosure provides a photovoltaic module, which includes multiple back-contact cells formed by the manufacturing method of the back-contact cells provided in the foregoing embodiments, or multiple back-contact cells provided in the foregoing embodiments, or multiple stacked cells provided in the foregoing embodiments. The photovoltaic module is used to convert received light energy into electrical energy. 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.

[0161] Reference Figure 13 , Figure 14 as well as Figure 10The photovoltaic module includes: a battery string, which is formed by connecting multiple back contact batteries 40 formed by the manufacturing method of back contact batteries provided in the foregoing embodiments, or by connecting multiple back contact batteries 40 provided in the foregoing embodiments, or by connecting multiple stacked batteries provided in the foregoing embodiments; an encapsulating film 41 for covering the surface of the battery string; and a cover plate 42 for covering the surface of the encapsulating film 41 away from the battery string.

[0162] in, Figure 13 A partial three-dimensional structural diagram of a cell string in a photovoltaic module provided in yet another embodiment of this disclosure; Figure 14 This is a partial cross-sectional structural diagram of a photovoltaic module provided in yet another embodiment of the present disclosure.

[0163] In some embodiments, the back contact battery 40 includes, but is not limited to, IBC (Interdigitated Back Contact), HBC (Heterojunction Back Contact), TBC (TOPCon Back Contact), HTBC (Heterojunction Tunnel Oxide Passivated Back Contact), or HPBC (Hybrid Passivated Back Contact).

[0164] In some cases, multiple back contact batteries 40 can be electrically connected via solder strips 43. It is worth noting that electrical connection actually means that both are made of conductive materials and are directly connected or connected via other conductive materials. Therefore, when the back contact battery 40 is generating electricity, there is an electrical connection between them.

[0165] It should be noted that, Figure 13 and Figure 14 This illustration only shows one positional relationship between the back contact batteries 40, where the side of each back contact battery 40 with electrodes faces the same side, and the solder strip 43 connects the same side of two adjacent back contact batteries 40 respectively. In other embodiments, the back contact batteries may also be arranged such that the side of each of two adjacent back contact batteries with electrodes is located on different sides, in which case the solder strip connects the different sides of the two adjacent back contact batteries.

[0166] In some embodiments, the back contact battery 40 is electrically connected in a single sheet or in multiple segments to form multiple battery strings, and the multiple battery strings are electrically connected in series and / or parallel. The back contact battery 40 can be a single sheet of battery or a slice of battery, where a slice of battery refers to a battery formed by cutting a single sheet of battery.

[0167] 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 front or back sides of the back contact battery 40, and the second encapsulating layer covers the other of the front or back sides of the back contact battery 40. Specifically, at least one of the first encapsulating layer or the second encapsulating layer may be an organic encapsulating film such as polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA), polyolefin thermoplastic elastomer (POE), or polyethylene glycol terephthalate (PET). Alternatively, at least one of the first encapsulating layer or the second encapsulating layer may 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.

[0168] 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.

[0169] 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 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation layer, and the second cover plate being opposite to the second encapsulation layer.

[0170] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the embodiments of this disclosure. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the embodiments of this disclosure; therefore, the scope of protection of the embodiments of this disclosure should be determined by the scope defined in the claims.

Claims

1. A method for manufacturing a back-contact battery, characterized in that, include: A substrate is provided, the substrate having alternating first and second regions; An initial passivation layer is formed on the first region and the second region; The initial passivation layer located in the second region is ablated using a first laser, and the remaining initial passivation layer located in the first region is the passivation layer; The surface of the substrate located in the second region is treated with an alkaline solution. The surface of the substrate located in the second region is acid-treated with an acidic solution.

2. The method for manufacturing a back contact battery according to claim 1, characterized in that, After the alkaline treatment and before the acidic treatment, the method for manufacturing the back contact battery further includes rinsing the surface of the substrate located in the second region.

3. The method for manufacturing a back contact battery according to claim 1, characterized in that, During the process of ablating the initial passivation layer with the first laser, the first laser carries a dopant source, and the first laser is used to cause the dopant element in the dopant source to diffuse into the substrate, so that a portion of the substrate located in the second region is transformed into a doped part; wherein, the alkaline treatment and the acidic treatment are performed on the doped part.

4. The method for manufacturing a back contact battery according to claim 1, characterized in that, The energy density of the first laser is E1, and the unit of E1 is J / cm². 2 The alkaline treatment duration is T, where T is in minutes; and the product of E1 and T is 0.15 to 0.

75.

5. The method for manufacturing a back contact battery according to claim 4, characterized in that, 0.5J / cm 2 ≤E1≤2.5J / cm 2 ; and / or, 5s≤T≤25s.

6. The method for manufacturing a back contact battery according to claim 1, characterized in that, The alkaline solution has a mass fraction of 0.5% to 5%; and / or the alkaline treatment temperature is 20°C to 40°C.

7. The method for manufacturing a back contact battery according to claim 1, characterized in that, After the acid treatment, the method for manufacturing the back contact battery further includes: An initial second doped conductive portion is formed on the side of the passivation layer away from the substrate; The initial second-doped conductive portion is annealed using a second laser to transform it into a second-doped conductive portion. The energy density of the second laser is lower than that of the first laser, and the crystallinity of the second-doped conductive portion is higher than that of the initial second-doped conductive portion.

8. The method for manufacturing a back contact battery according to claim 7, characterized in that, The step of forming the initial passivation layer includes: forming an initial first doped conductive portion on the first region and the second region; in the step of forming the passivation layer, the initial first doped conductive portion remaining in the first region is a first doped conductive portion; The step of forming the initial second doped conductive portion includes: growing the initial second doped conductive portion in situ on the side of the first doped conductive portion away from the substrate; Wherein, the first doped conductive portion and the initial second doped conductive portion are doped with the same type of doping element, the doping concentration of the doping element in the first doped conductive portion is a first concentration, the doping concentration of the doping element in the initial second doped conductive portion is a second concentration, the second concentration is greater than the first concentration; and / or, the crystallinity of the second doped conductive portion is higher than the crystallinity of the first doped conductive portion.

9. The method for manufacturing a back contact battery according to claim 1, characterized in that, In the step of ablating the initial passivation layer located in the second region using the first laser, the edges of the remaining initial passivation layer located in the first region are modified so that the connection between the side of the passivation layer near the second region and the top surface of the passivation layer away from the substrate is an arc surface.

10. A back-contact battery, characterized in that, The back contact battery is formed by the manufacturing method of any one of claims 1 to 9, wherein the back contact battery comprises: A substrate having alternating first and second regions; Passivation layer, located in the first region; The surface of the substrate located in the second region underwent alkaline treatment and acid treatment in sequence.

11. The back contact battery according to claim 10, characterized in that, The junction between the side of the passivation layer near the second region and the top surface of the passivation layer away from the substrate is an arc surface; and / or, The substrate located in the second region includes a doped portion located on the side of the substrate close to the passivation layer.

12. The back contact battery according to claim 10, characterized in that, Also includes: The second doped conductive portion is located on the side of the passivation layer away from the substrate; A dielectric layer is located on the surface jointly formed by the second doped conductive portion and the substrate located in the second region; The first electrode is embedded in the dielectric layer located in the first region and electrically connected to the second doped conductive portion; The second electrode is embedded in the dielectric layer located in the second region and electrically connected to the substrate.

13. A stacked battery, characterized in that, include: The bottom battery is a back contact battery formed by the manufacturing method of a back contact battery as described in any one of claims 1 to 9, or a back contact battery as described in any one of claims 10 to 12; A perovskite solar cell, wherein the perovskite solar cell is located on one side of the bottom solar cell.

14. A photovoltaic module, characterized in that, include: The battery string is formed by connecting multiple back contact batteries formed by the manufacturing method of the back contact batteries as described in any one of claims 1 to 9, or by connecting multiple back contact batteries as described in any one of claims 10 to 12, or by connecting multiple stacked batteries as described in claim 13. 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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