Back contact cell and manufacturing method thereof, back contact laminated cell and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a back contact cell and a manufacturing method thereof, a back contact laminated cell and a photovoltaic module, and the manufacturing method comprises the steps: providing a substrate with a first surface and a second surface which are opposite to each other, and the second surface comprises a first region and a second region which are alternately arranged along a second direction; forming a laminated structure comprising a tunneling layer, a doped polycrystalline silicon layer and a first protection layer which are stacked on the first region; forming an initial second passivation lamination layer which covers the second surface and comprises an intrinsic amorphous silicon film and a doped amorphous silicon film which are stacked; forming a second protection layer on one side, far away from the substrate, of the doped amorphous silicon film; etching the first region by adopting a first laser etching process; and taking the second protection layer on the second region as an etching barrier layer, taking the first protection layer as an etching stop layer, and removing the initial second passivation lamination layer or the second protection layer and the initial second passivation lamination layer remaining on the first region by adopting a first etching solution, thereby at least facilitating the improvement of the photoelectric conversion efficiency of the back contact battery.

Description

Technical Field

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

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

[0003] However, in order to improve the photoelectric conversion efficiency of BC cells, a passivated contact structure is also designed on the back surface of BC cells. Based on this, the preparation process of the existing back contact battery with a passivated contact structure is usually relatively complex. Moreover, when designing different passivated contact structures in different regions to contact grid lines with different polarities, both laser and etching solution are required. It is not only difficult to completely remove the passivated contact structure to be removed, but also easy to cause various damages to the passivated contact structure to be retained, resulting in poor stability of the preparation process of the back contact battery and low photoelectric conversion efficiency of the prepared back contact battery.

[0004] Therefore, how to improve the photoelectric conversion efficiency of BC cells still needs further research. Summary of the Invention

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

[0006] According to some embodiments of the present disclosure, on the one hand, a method for manufacturing a back contact battery is provided, including: providing a substrate having a first surface and a second surface opposite to each other in a first direction, the second surface including a first region and a second region arranged alternately in a second direction, the first direction being the thickness direction of the substrate, and the second direction intersecting with the first direction; forming a stacked structure on the first region, the stacked structure including a tunneling layer, a doped polysilicon layer, and a first protective layer stacked along the first direction; forming an initial second passivation stack on the surface jointly formed by the second surface and the stacked structure, the initial second passivation stack including an intrinsic amorphous silicon film and a doped amorphous silicon film stacked along the first direction; forming a second protective layer on a side of the doped amorphous silicon film away from the intrinsic amorphous silicon film; using a first laser etching process to etch the second protective layer and the initial second passivation stack located on the first region, and part of the initial second passivation stack, or part of the second protective layer and part of the initial second passivation stack remain on the first region; using the second protective layer located on the second region as an etching stop layer and using the first protective layer as an etching stop layer, and using a first etching solution to remove the initial second passivation stack remaining on the first region, or to remove the second protective layer and the initial second passivation stack remaining on the first region, and the remaining initial second passivation stack located on the second region is the second passivation stack, and the tunneling layer and the doped polysilicon layer constitute the first passivation stack.

[0007] In some embodiments, after forming the stacked structure and before forming the initial second passivation stack, the method for manufacturing the back contact battery further includes: performing texturing treatment on the first surface to convert the first surface into a textured surface; forming a passivation and antireflection layer on the textured surface; wherein, the process temperature used in the step of forming the passivation and antireflection layer is a first temperature, and the process temperature used in the step of forming the second protective layer is a second temperature, and the first temperature is greater than or equal to the second temperature.

[0008] In some embodiments, the second temperature is 150°C to 250°C.

[0009] In some embodiments, the steps of forming the passivation and antireflection layer include: adopting a first deposition process to form an aluminum oxide film on the textured surface, and the aluminum oxide film is also formed on a partial area of the second surface and on the side surface connecting the first surface and the second surface; adopting a second deposition process to form a silicon nitride film on the side of the aluminum oxide film away from the substrate; adopting a chain etching process to remove the silicon nitride film on the partial area of the second surface and on the side surface, and the remaining silicon nitride film on the first surface is the silicon nitride layer; using the silicon nitride layer as an etching barrier layer, and adopting a third etching solution to remove the aluminum oxide film on the partial area of the second surface and on the side surface, and the remaining aluminum oxide film on the first surface is the aluminum oxide layer, and the passivation and antireflection layer includes the aluminum oxide layer and the silicon nitride layer.

[0010] In some embodiments, the steps of forming the stacked structure include: forming an initial stacked structure on the second surface, and the initial stacked structure includes a tunneling film, a doped polysilicon film, and a first protective film stacked along the first direction; adopting a second laser etching process to preliminarily etch the initial stacked structure located on the second region to remove a partial thickness of the initial stacked structure, and performing a laser modification process on at least a partial thickness of the initial stacked structure; adopting a second etching solution to remove the remaining initial stacked structure located on the second region, and the remaining initial stacked structure located on the first region is the stacked structure, the remaining tunneling film located on the first region is the tunneling layer, the remaining doped polysilicon film located on the first region is the doped polysilicon layer, and the remaining first protective film located on the first region is the first protective layer.

[0011] In some embodiments, the reaction temperature of the first etching solution is less than the reaction temperature of the second etching solution; and / or, the reaction time of the first etching solution is less than the reaction time of the second etching solution; and / or, both the first etching solution and the second etching solution are potassium hydroxide solutions, and the concentration of potassium hydroxide in the first etching solution is less than the concentration in the second etching solution.

[0012] In some embodiments, in the steps of forming the stacked structure, the second etching solution also etches the substrate located in the second region, the surface of the substrate located in the second region is the second surface, the surface of the substrate located in the first region is the first surface, and taking the first surface as the reference surface, the second surface is lower than the first surface.

[0013] In some embodiments, along the first direction, the distance between the second surface and the first surface is 3 μm to 10 μm.

[0014] In some embodiments, the laser used in the first laser etching process is the first laser, and the laser used in the second laser etching process is the second laser, and the wavelength of the first laser is less than the wavelength of the second laser.

[0015] In some embodiments, a first laser is generated by a first laser device in the first laser etching process; a second laser is generated by a second laser device in the second laser etching process; wherein, the laser scanning speed of the first laser device is greater than the laser scanning speed of the second laser device; and / or, the power of the first laser device is less than the power of the second laser device; and / or, the frequency of the first laser device is less than the frequency of the second laser device.

[0016] In some embodiments, the laser scanning speed of the first laser device is 40 m / s to 60 m / s, and the laser scanning speed of the second laser device is 30 m / s to 50 m / s; and / or, the power of the first laser device is 10 W to 30 W, and the power of the second laser device is 60 W to 80 W; and / or, the frequency of the first laser device is 900 kHz to 1100 kHz, and the frequency of the second laser device is 1100 kHz to 1300 kHz.

[0017] In some embodiments, after forming the second passivation stack, the manufacturing method of the back contact battery further includes: using an acid pickling process to remove the second protective layer located on the second region and the first protective layer.

[0018] According to some embodiments of the present disclosure, on the other hand, the present disclosure also provides a back contact battery, which is the back contact battery formed by the manufacturing method of the back contact battery as described in any one of the above.

[0019] According to some embodiments of the present disclosure, on another aspect, the present disclosure also provides a back contact stacked battery, including: a bottom battery, which is the back contact battery formed by the manufacturing method of the back contact battery as described in any one of the above, or the back contact battery as described above; a top battery, which is one of a perovskite battery, a donor-acceptor battery, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell, and the top battery is located on one side of the bottom battery.

[0020] According to some embodiments of the present disclosure, on yet another aspect, the present disclosure also provides a photovoltaic module, including: a battery string, which is formed by connecting a plurality of back contact batteries formed by the manufacturing method of the back contact battery as described in any one of the above, or a plurality of back contact batteries as described above, or a plurality of back contact stacked batteries as described above; an encapsulation adhesive film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulation adhesive film facing away from the battery string.

[0021] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages: Before performing the first laser etching process, not only is a first protective layer formed on the first region, but also a second protective layer is formed on the side of the doped amorphous silicon film away from the intrinsic amorphous silicon film. Then, on the premise of not causing laser damage and over-etching to the stacked structure, the first laser etching process is first used to preliminarily etch the second protective layer and the initial second passivation stack located on the first region, and then, with the cooperation of the second protective layer and the first protective layer located on the second region, a first etching solution is used to supplement the etching of the initial second passivation stack remaining on the first region, or the second protective layer and the initial second passivation stack remaining on the first region, so as to ensure that in the finally formed back contact battery, the first passivation stack composed of the tunneling layer and the doped polysilicon layer is only located in the first region, and the second passivation stack is only located in the second region, thereby facilitating the reduction of the series resistance of the finally formed back contact battery and the improvement of the fill factor of the back contact battery, and thus improving the photoelectric conversion efficiency of the back contact battery. Moreover, with the mutual cooperation of each step, it is beneficial to improve the stability of the manufacturing process of the back contact battery and reduce the difference in the photoelectric conversion efficiency between different back contact energy batteries prepared, thereby improving the yield of the prepared back contact battery. Description of the Drawings

[0022] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments. Unless otherwise stated, the figures in the drawings do not constitute a proportional limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the traditional technology, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is a flowchart of a method for manufacturing a back contact battery provided by an embodiment of the present disclosure; Figure 2 It is a partial cross-sectional schematic diagram of a substrate in a method for manufacturing a back contact battery provided by an embodiment of the present disclosure; Figure 3 It is a partial cross-sectional schematic diagram after forming an initial stack structure in a method for manufacturing a back contact battery provided by an embodiment of the present disclosure; Figure 4 It is a partial cross-sectional schematic diagram after forming a stack structure in a method for manufacturing a back contact battery provided by an embodiment of the present disclosure; Figure 5A partial cross-sectional schematic diagram after forming an aluminum oxide film and a silicon nitride film in the manufacturing method of a back-contact battery provided by an embodiment of the present disclosure; Figure 6 A partial cross-sectional schematic diagram after forming a silicon nitride layer in the manufacturing method of a back-contact battery provided by an embodiment of the present disclosure; Figure 7 A partial cross-sectional schematic diagram after forming an aluminum oxide layer in the manufacturing method of a back-contact battery provided by an embodiment of the present disclosure; Figure 8 A partial cross-sectional schematic diagram after forming an initial second passivation stack in the manufacturing method of a back-contact battery provided by an embodiment of the present disclosure; Figure 9 A partial cross-sectional schematic diagram after forming a second protective layer in the manufacturing method of a back-contact battery provided by an embodiment of the present disclosure; Figure 10 A partial cross-sectional schematic diagram after performing a first laser etching process in the manufacturing method of a back-contact battery provided by an embodiment of the present disclosure; Figure 11 A partial cross-sectional schematic diagram after etching with a first etching solution in the manufacturing method of a back-contact battery provided by an embodiment of the present disclosure; Figure 12 A partial cross-sectional schematic diagram after performing a pickling process in the manufacturing method of a back-contact battery provided by an embodiment of the present disclosure; Figure 13 A partial cross-sectional schematic diagram of a back-contact stacked battery provided by another embodiment of the present disclosure; Figure 14 A schematic diagram of a connection method between a top cell and a bottom cell in a back-contact stacked battery provided by another embodiment of the present disclosure; Figure 15 A schematic diagram of another connection method between a top cell and a bottom cell in a back-contact stacked battery provided by another embodiment of the present disclosure; Figure 16 A schematic diagram of yet another connection method between a top cell and a bottom cell in a back-contact stacked battery provided by another embodiment of the present disclosure.

[0024] Explanation of reference numerals: 100. Substrate; 110. First surface; 120. Second surface; 130. First region; 140. Second region; 150. Side surface; 101. Stacked structure; 111. Initial stacked structure; 102. Tunneling layer; 112. Tunneling film; 103. Doped polysilicon layer; 113. Doped polysilicon film; 123. First passivation stack; 104. First protective layer; 114. First protective film; 105. Initial second passivation stack; 115. Second passivation stack; 106. Intrinsic amorphous silicon film; 116. Intrinsic amorphous silicon layer; 107. Doped amorphous silicon film; 117. Doped amorphous silicon layer; 108. Second protective layer; 109. Passivation and antireflection layer; 119. Aluminum oxide film; 129. Silicon nitride film; 139. Silicon nitride layer; 149. Aluminum oxide layer; 159. Bottom cell; 169. Top cell. Detailed implementation manners

[0025] As can be seen from the background art, the photoelectric conversion efficiency of the back contact cell needs to be improved.

[0026] The embodiments of the present disclosure provide a back contact cell, a manufacturing method thereof, a back contact stacked cell, and a photovoltaic module. In the manufacturing method of the back contact cell, before performing the first laser etching process, not only a first protective layer is formed on the first region, but also a second protective layer is formed on the side of the doped amorphous silicon film away from the intrinsic amorphous silicon film. Then, on the premise of not causing laser damage and over-etching to the stacked structure, the first laser etching process is first used to preliminarily etch the second protective layer and the initial second passivation stack located on the first region, and then, under the cooperation of the second protective layer and the first protective layer located on the second region, a first etching solution is used to supplement the etching of the initial second passivation stack remaining on the first region, or the second protective layer and the initial second passivation stack remaining on the first region, so as to ensure that in the finally formed back contact cell, the first passivation stack composed of the tunneling layer and the doped polysilicon layer is only located in the first region, and the second passivation stack is only located in the second region, thereby being beneficial to reducing the series resistance of the finally formed back contact cell and improving the fill factor of the back contact cell, and thus improving the photoelectric conversion efficiency of the back contact cell. Moreover, with the mutual cooperation of each step, it is beneficial to improve the stability of the manufacturing process of the back contact cell and reduce the difference in the photoelectric conversion efficiency between different manufactured back contact cells, thereby improving the yield of the manufactured back contact cells.

[0027] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality" is more than two, unless otherwise clearly and specifically defined.

[0028] References to "embodiments" in this disclosure mean that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present disclosure. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment each time, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of the association relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can mean: the existence of A, the simultaneous existence of A and B, and the existence of B. Additionally, the character " / " in this document generally represents an "or" relationship between the associated objects before and after.

[0030] In the description of the embodiments of the present disclosure, the term "plurality" refers to two or more (including two). Similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).

[0031] In the description of the embodiments of the present disclosure, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the embodiments of the present disclosure.

[0032] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "install", "connect", "couple", "fix", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0033] In the accompanying drawings corresponding to the embodiments of the present disclosure, for better understanding and description, the thickness and area of the layers are enlarged. When describing a component (such as a layer, film, region, or substrate) being on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. Conversely, when describing a component being on the surface of another component or when the surface of one component forms or is provided with another component, it means there is no third component between the two components. In addition, when describing a component being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0034] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise stated, other components are not excluded, and other components may further be included. In addition, when components such as layers, films, regions, or plates are referred to as being "on / at" another component, it can be "directly on" the other component (i.e., on the surface of the other component with no other components between them), or there can be another component between them. In addition, when components such as layers, films, regions, plates, etc. are "directly located on" another component, or when layers, films, regions, plates, etc. are located on the surface of another component, it means there are no other components located between them.

[0035] The terms used in the description of the various embodiments herein are only for describing specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is also intended to include the plural form, unless the context clearly indicates otherwise. Among them, the component includes components such as layers, films, regions, or plates.

[0036] The following will elaborate on the embodiments of the present disclosure in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are presented for the reader to better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions required to be protected by the embodiments of the present disclosure can be implemented.

[0037] An embodiment of the present disclosure provides a method for manufacturing a back-contact battery. The following will elaborate in detail on the method for manufacturing a back-contact battery provided by an embodiment of the present disclosure in conjunction with the accompanying drawings.

[0038] With reference to Figures 1 to 11 , Figure 1 is a flowchart of a method for manufacturing a back-contact battery provided by an embodiment of the present disclosure. The method for manufacturing a back-contact battery at least includes the following steps: S1: With reference to Figure 2 ,Figure 2 A partial cross-sectional view of a substrate in a method for manufacturing a back-contact battery provided by an embodiment of the present disclosure. A substrate 100 is provided. The substrate 100 has a first surface 110 and a second surface 120 opposite to each other along a first direction X. The second surface 120 includes a first region 130 and a second region 140 arranged alternately along a second direction Y. The first direction X is the thickness direction of the substrate 100, and the second direction Y intersects the first direction X.

[0039] It should be noted that, for the sake of clarity of the illustration, Figure 2 only one first region 130 and one second region 140 are schematically shown. In actual applications, the second surface includes a plurality of first regions and a plurality of second regions. A first region and a second region are arranged alternately along the second direction. In other words, there is a first region between two adjacent second regions, and there is a second region between two adjacent first regions.

[0040] S2: With reference to Figure 3 and Figure 4 , a stacked structure 101 is formed on the first region 130. The stacked structure 101 includes a tunneling layer 102, a doped polysilicon layer 103, and a first protective layer 104 stacked along the first direction X. It should be noted that Figure 3 and Figure 4 will be described in detail later.

[0041] S3: With reference to Figures 5 to 8 , an initial second passivation stack 105 is formed on the surface jointly constituted by the second surface 120 and the stacked structure 101. The initial second passivation stack 105 includes an intrinsic amorphous silicon film 106 and a doped amorphous silicon film 107 stacked along the first direction X. It should be noted that Figure 8 is a partial cross-sectional view after forming the initial second passivation stack in a method for manufacturing a back-contact battery provided by an embodiment of the present disclosure. Figures 5 to 7 will be described in detail later.

[0042] S4: With reference to Figure 9 , Figure 9 is a partial cross-sectional view after forming the second protective layer in a method for manufacturing a back-contact battery provided by an embodiment of the present disclosure. A second protective layer 108 is formed on the side of the doped amorphous silicon film 107 away from the intrinsic amorphous silicon film 106.

[0043] S5: With reference to Figure 9 and Figure 10 , using a first laser etching process, the second protective layer 108 and the initial second passivation stack 105 located on the first region 130 are etched, and part of the initial second passivation stack 105, or part of the second protective layer 108 and part of the initial second passivation stack 105 remain on the first region 130.

[0044] It should be noted that Figure 10 FIG. is a partial cross-sectional schematic diagram after the first laser etching process in the manufacturing method of the back contact battery provided in an embodiment of the present disclosure. In addition, Figure 10 Taking the example that after the first laser etching process, part of the second protective layer 108 and part of the initial second passivation stack 105 remain on the first region 130, in practical applications, the first laser etching process can also remove all the second protective layers located on the first region, and in the initial second passivation stack, both the doped amorphous silicon film and the intrinsic amorphous silicon film can remain, or only the intrinsic amorphous silicon film can remain.

[0045] S6: With reference to Figure 10 and Figure 11 , using the second protective layer located on the second region 140 as an etching stop layer and the first protective layer 104 as an etching stop layer, and using a first etching solution, remove the initial second passivation stack 105 remaining on the first region 130, or remove the second protective layer 108 and the initial second passivation stack 105 remaining on the first region 130, and the remaining initial second passivation stack 105 located on the second region 140 is the second passivation stack 115.

[0046] It should be noted that the remaining intrinsic amorphous silicon film 106 located on the second region 140 can be regarded as the intrinsic amorphous silicon layer 116, the remaining doped amorphous silicon film 107 located on the second region 140 can be regarded as the doped amorphous silicon layer 117, and the second passivation stack 115 includes the intrinsic amorphous silicon layer 116 and the doped amorphous silicon layer 117 stacked along the first direction X.

[0047] Among them, Figure 11 FIG. is a partial cross-sectional schematic diagram after etching with the first etching solution in the manufacturing method of the back contact battery provided in an embodiment of the present disclosure.

[0048] It should be noted that when performing step S5: using the first laser etching process to etch the second protective layer 108 and the initial second passivation stack 105 located on the first region 130, on the one hand, due to the limitation of the accuracy of the laser itself, such as the insufficient uniformity of the laser energy, on the other hand, to avoid laser damage to the stack structure 101 located on the first region 130, and on the other hand, to avoid over-etching of the stack structure 101 by the first laser etching process, the laser energy used in the first laser etching process is limited. Therefore, after the first laser etching process, part of the initial second passivation stack 105, or part of the second protective layer 108 and part of the initial second passivation stack 105 remain on the first region 130.

[0049] On this basis, a first protective layer 104 and a second protective layer 108 are designed before the first laser etching process. Subsequently, the second protective layer located on the second region 140 is used as an etching stop layer, and the first protective layer 104 is used as an etching stop layer. A first etching solution is used to remove the initial second passivation stack 105 remaining on the first region 130, or to remove the second protective layer 108 and the initial second passivation stack 105 remaining on the first region 130, so as to ensure that in the finally formed back contact battery, the first passivation stack 123 composed of the tunneling layer 102 and the doped polysilicon layer 103 is only located in the first region 130, and the second passivation stack 115 is only located in the second region 140. In this way, on the one hand, it can effectively avoid the initial second passivation stack 105 remaining on the stack structure 101, so as to avoid the increase in the series resistance and the decrease in the fill factor of the back contact battery caused by the initial second passivation stack 105 remaining on the first region 130. On the other hand, based on the supplementary etching of the first etching solution, it is beneficial to reduce the laser energy used in the first laser etching process in step S5, so as to avoid laser damage to the stack structure 101 located on the first region 130 and avoid over-etching of the stack structure 101 by the first laser etching process. On the other hand, in the step of supplementary etching of the first etching solution, not only can the second protective layer 108 located on the second region 140 be used as an etching stop layer to avoid etching the initial second passivation stack 105 located on the second region 140 by the first etching solution, but also the first protective layer 104 can be used as an etching stop layer to avoid over-etching of the stack structure 101 by the first etching solution, for example, to avoid etching into the doped polysilicon layer 103. With such a multi-faceted cooperative design, it is not only beneficial to improve the photoelectric conversion efficiency of the back contact battery, but also beneficial to improve the stability of the preparation process of the back contact battery, and reduce the difference in the photoelectric conversion efficiency between different prepared back contact batteries, thereby improving the yield of the prepared back contact battery.

[0050] In other words, before performing the first laser etching process, not only is the first protective layer 104 formed on the first region 130, but also the second protective layer 108 is formed on the side of the doped amorphous silicon film 107 away from the intrinsic amorphous silicon film 106. Then, on the premise of not causing laser damage and over-etching to the stacked structure 101, the first laser etching process is first used to preliminarily etch the second protective layer 108 and the initial second passivation stack 105 located on the first region 130, and then, with the cooperation of the second protective layer 108 and the first protective layer 104 located on the second region 140, the first etching solution is used to supplement the etching of the second protective layer 108 and the initial second passivation stack 105 located on the first region 130, so as to ensure that in the finally formed back-contact battery, the stacked structure 101 is only located in the first region 130, and the second passivation stack 115 is only located in the second region 140, which is beneficial to reducing the series resistance of the finally formed back-contact battery and improving the fill factor of the back-contact battery, thereby improving the photoelectric conversion efficiency of the back-contact battery. Moreover, with the mutual cooperation of steps S2 to S6, it is beneficial to improve the stability of the manufacturing process of the back-contact battery and reduce the difference in photoelectric conversion efficiency between different manufactured back-contact batteries, thereby improving the yield of the manufactured back-contact battery.

[0051] It should be noted that the back-contact battery provided by an embodiment of the present disclosure is a photovoltaic battery formed by combining the Topcon (Tunnel Oxide Passivated Contact) technology and the HJT (Heterojunction with Intrinsic Thin-layer) technology on the basis of the BC battery as the platform technology.

[0052] The manufacturing method of the back-contact battery provided by an embodiment of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0053] In some embodiments, referring to Figure 4 , the doped polysilicon layer 103 formed in step S2 is doped with a first type of doping element. Referring to Figure 8 , the doped amorphous silicon film 107 formed in step S3 is doped with a second type of doping element. The first type of doping element is one of the N-type doping element and the P-type doping element, and the second type of doping element is the other of the N-type doping element and the P-type doping element.

[0054] In some examples, the N-type doping element may 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 element, and the P-type doping element may be at least one of Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0055] In some embodiments, the substrate 100 is configured to receive incident light and generate photo-generated carriers.

[0056] In some cases, the material of the substrate 100 may be an elemental semiconductor material. Optionally, the elemental semiconductor material is composed of a single element, for example, it may be silicon or germanium. Among them, the elemental semiconductor material may be in single crystal state, polycrystalline state, amorphous state, or microcrystalline state (a state with both single crystal state and amorphous state is called microcrystalline state). For example, silicon may be at least one of single crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0057] In other cases, the material of the substrate 100 may be a compound semiconductor material. Optionally, common compound semiconductor materials include but are not limited to materials such as silicon germanide, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, or copper indium selenide.

[0058] In still other cases, the substrate 100 may also be a sapphire substrate, a silicon-on-insulator substrate, or a germanium-on-insulator substrate.

[0059] In some embodiments, the substrate 100 may be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type doping element, and the P-type semiconductor substrate is doped with a P-type element.

[0060] In some embodiments, with reference to Figures 5 to 8 , after performing step S2, that is, forming the stacked structure 101, and before performing step S3, that is, forming the initial second passivation stack 105, the manufacturing method of the back-contact battery may further include the following steps: With reference to Figure 4 and Figure 5 , the first surface 110 is textured to convert the first surface 110 into a textured surface; with reference to Figures 5 to 8 , a passivation and antireflection layer 109 is formed on the textured surface; wherein, the process temperature used in the step of forming the passivation and antireflection layer 109 is the first temperature, and the process temperature used in the step of forming the second protective layer 108 (refer to Figure 9 ) is the second temperature, and the first temperature is greater than or equal to the second temperature.

[0061] It should be noted that in the subsequent step S3 of forming the initial second passivation stack 105, both the intrinsic amorphous silicon film 106 and the doped amorphous silicon film 107 are in amorphous state. To ensure the excellent passivation performance of the intrinsic amorphous silicon film 106 and the doped amorphous silicon film 107 for the second region 140 and prevent the photoelectric conversion efficiency of the back contact battery from decreasing, the process temperature of other process steps after forming the initial second passivation stack 105 should not be too high to avoid affecting the amorphous state of the intrinsic amorphous silicon film 106 and the doped amorphous silicon film 107. Based on this, before forming the initial second passivation stack 105 on the second surface 120, that is, after texturing the first surface 110 and forming the passivation and antireflection layer 109 on the textured surface, even if the first temperature is greater than the second temperature, it is possible to avoid the adverse effect of the process temperature of forming the passivation and antireflection layer 109 on the amorphous state of the intrinsic amorphous silicon film 106 and the doped amorphous silicon film 107, so as to ensure the excellent passivation performance of the finally formed second passivation stack 115 for the second region 140, improve the light trapping effect of the first surface 110 on incident light, and ensure good passivation treatment of the second surface 120, thereby further improving the photoelectric conversion efficiency of the back contact battery.

[0062] It should be noted that inserting the process step of texturing the first surface 110 and forming the passivation and antireflection layer 109 on the textured surface between the step of preparing the stack structure 101 for the first region 130 of the second surface 120 and the step of preparing the second passivation stack 115 for the second region 140 of the second surface 120 is beneficial for making the process temperature of forming the passivation and antireflection layer 109 on the textured surface, that is, the first temperature, not be overly restricted. It can be prepared using a relatively high process temperature, that is, designing the first temperature to be greater than the second temperature, or it can be prepared using a relatively low process temperature adapted to the subsequent formed intrinsic amorphous silicon film 106 and doped amorphous silicon film 107, that is, designing the first temperature to be equal to the second temperature.

[0063] In addition, the process temperature of texturing the first surface 110 is generally also lower than the process temperature used in the step of forming the second protective layer 108, that is, the second temperature. In some examples, the process temperature of texturing the first surface 110 is generally lower than 100 °C.

[0064] In some cases, the second temperature can be 150 °C to 250 °C. For example, it can be 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C or 240 °C, etc.

[0065] In some cases, a plasma enhanced chemical vapor deposition (PECVD) process can be used to form the second protective layer 108. It should be noted that the PECVD process uses plasma to enhance the deposition process, thereby enabling a lower process temperature and a faster deposition rate, which is beneficial to ensuring the process temperature adopted in the step of forming the second protective layer 108, that is, the second temperature is relatively low, and improving the manufacturing efficiency of the back contact battery.

[0066] In some cases, with reference to Figures 5 to 7 , the step of forming the passivation and antireflection layer 109 may include: with reference to Figure 5 , using a first deposition process to form an aluminum oxide film 119 on the textured surface, and the aluminum oxide film 119 is also formed on a partial area of the second surface 120 and on the side surface 150 connecting the first surface 110 and the second surface 120; continuing to refer to Figure 5 , using a second deposition process to form a silicon nitride film 129 on the side of the aluminum oxide film 119 away from the substrate 100; with reference to Figure 5 and Figure 6 , using a chain etching process to remove the silicon nitride film 129 located on a partial area of the second surface 120 and the side surface 150, and the remaining silicon nitride film 129 located on the first surface 110 is the silicon nitride layer 139; with reference to Figure 6 and Figure 7 , using the silicon nitride layer 139 as an etching barrier layer and a third etching solution to remove the aluminum oxide film 119 located on a partial area of the second surface 120 and the side surface 150, and the remaining aluminum oxide film 119 located on the first surface 110 is the aluminum oxide layer 149. The passivation and antireflection layer 109 includes the aluminum oxide layer 149 and the silicon nitride layer 139.

[0067] Wherein, Figure 5 is a partial cross-sectional schematic diagram after forming the aluminum oxide film and the silicon nitride film in the manufacturing method of the back contact battery provided by an embodiment of the present disclosure; Figure 6 is a partial cross-sectional schematic diagram after forming the silicon nitride layer in the manufacturing method of the back contact battery provided by an embodiment of the present disclosure; Figure 7 is a partial cross-sectional schematic diagram after forming the aluminum oxide layer in the manufacturing method of the back contact battery provided by an embodiment of the present disclosure. In addition, to show the side surface 150, Figure 5 and Figure 6 only show a first region 130 and a second region 140 between two side surfaces 150. In practical applications, there are multiple first regions and multiple second regions between the opposite two side surfaces.

[0068] It should be noted that during the step of forming the alumina film 119, there is a phenomenon of overplating on the alumina film 119; during the step of forming the silicon nitride film 129, there is also a phenomenon of overplating on the silicon nitride film 129. Based on this, in the follow-up, different etching processes need to be used to sequentially remove the silicon nitride film 129 and the alumina film 119 formed by overplating, that is, to remove the silicon nitride film 129 and the alumina film 119 in the places where the silicon nitride film 129 and the alumina film 119 are not required to be formed. First, the silicon nitride film 129 on the partial area of the second surface 120 and the side surface 150 is removed by means of a chain etching process, and the silicon nitride film 129 on the first surface 110 is reserved as the silicon nitride layer 139. When etching the alumina film 119 formed by overplating subsequently, the silicon nitride layer 139 can be used as an etching barrier layer, and a third etching solution is used to remove the alumina film 119 on the partial area of the second surface 120 and the side surface 150. In this way, based on the protection of the silicon nitride layer 139 on the alumina film 119 on the first surface 110, there is no need to use a chain etching process to remove the silicon nitride film 129 formed by overplating. For example, a tank etching process can be used to remove the silicon nitride film 129 formed by overplating, which is beneficial to reducing the process cost of manufacturing the back contact battery.

[0069] It should be noted that in practical applications, on the basis of using the silicon nitride layer as an etching barrier layer, a chain etching process can also be used to remove the alumina film on the partial area of the second surface and the side surface. In other words, based on the protection of the silicon nitride layer, in the step of forming the alumina layer in the manufacturing method of the back contact battery provided by an embodiment of the present disclosure, a variety of different etching processes can be applied.

[0070] In some embodiments, with reference to Figure 3 and Figure 4 , the step of forming the stacked structure 101 may include: with reference to Figure 3 , an initial stacked structure 111 is formed on the second surface 120, and the initial stacked structure 111 includes a tunneling film 112, a doped polysilicon film 113, and a first protective film 114 stacked along the first direction X; with reference to Figure 3 and Figure 4 , a second laser etching process is used to preliminarily etch the initial stacked structure 111 located in the second region 140 to remove a partial thickness of the initial stacked structure 111, and at least a partial thickness of the initial stacked structure 111 is subjected to laser modification treatment; continuing to combine with reference to Figure 3 and Figure 4, the remaining initial stack structure 111 located on the second region 140 is removed using a second etchant. The remaining initial stack structure 111 located on the first region 130 is the stack structure 101. The remaining tunneling film 112 located on the first region 130 is the tunneling layer 102. The remaining doped polysilicon film 113 located on the first region 130 is the doped polysilicon layer 103. The remaining first protective film 114 located on the first region 130 is the first protective layer 104.

[0071] Among them, Figure 3 is a partial cross-sectional schematic diagram after forming the initial stack structure in the manufacturing method of the back contact battery provided by an embodiment of the present disclosure; Figure 4 is a partial cross-sectional schematic diagram after forming the stack structure in the manufacturing method of the back contact battery provided by an embodiment of the present disclosure.

[0072] It should be noted that in the step of performing the second laser etching process, the laser not only etches a part of the thickness of the first protective film 114 located in the second region 140, but also at least modifies the remaining first protective film 114 located in the second region 140, making the remaining first protective film 114 located in the second region 140 easier to be etched by the second etchant than the first protective film 114 located in the first region 130, that is, the subsequently formed first protective layer 104. It should be noted that the doped polysilicon film 113 or the tunneling film 112 located in the second region 140 may also be affected by the laser in the second laser etching process and undergo modification, making the subsequently located doped polysilicon film 113 or tunneling film 112 in the second region 140 easier to be etched by the second etchant.

[0073] In other words, in the step of using the second etchant, the first protective film 114 located in the first region 130 can serve as an etching barrier layer, which is beneficial to removing the first protective film 114, the tunneling film 112, and the doped polysilicon film 113 located in the second region 140 completely while avoiding the etching of the doped polysilicon film 113 and the tunneling film 112 located in the first region 130 by the second etchant, so as to expose the substrate 100 located in the second region 140.

[0074] In some cases, the tunneling film 112, the doped polysilicon film 113, and the first protective film 114 can be formed by using a low-pressure chemical vapor deposition (LPCVD, Low Pressure Chemical Vapor Deposition) process. It should be noted that the LPCVD process does not use plasma, and the deposition process relies on low pressure and thermal energy to drive chemical reactions, which is beneficial to forming high-quality and uniform-thickness thin films, thereby being beneficial to improving the film-forming quality of the tunneling film 112, the doped polysilicon film 113, and the first protective film 114, so as to improve the passivation effect of the finally formed first passivation stack 123 on the first region 130.

[0075] In some embodiments, with reference to Figure 3 and Figure 4 , a second etching solution is used to remove the remaining initial stacked structure 111 on the second region 140; with reference to Figure 10 and Figure 11 , a first etching solution is used to remove the remaining initial second passivation stack 105 on the first region 130, or to remove the second protective layer 108 and the initial second passivation stack 105 remaining on the first region 130. It should be noted that in the step of using the first etching solution, the stacked structure 101 has been formed on the first region 130, and the first protective layer 104, as an etching stop layer, may also be damaged due to over-etching of the first etching solution. To avoid over-etching of the stacked structure 101 by the first etching solution and affecting the passivation effect of the first passivation stack 123 on the first region 130, the relevant parameters of the first etching solution can be adjusted to ensure the protective effect of the first protective layer 104 on the doped polysilicon layer 103 and the tunneling layer 102.

[0076] In some cases, the reaction temperature of the first etching solution can be lower than that of the second etching solution. Thus, compared with the reaction temperature of the second etching solution, by reducing the reaction temperature of the first etching solution, the probability of over-etching of the first protective layer 104 by the first etching solution can be reduced, so as to improve the yield of the formed back contact battery. In addition, the first laser etching process has preliminarily etched the second protective layer 108 and the initial second passivation stack 105 on the first region 130. In the step of using the first etching solution to supplement the etching of the second protective layer 108 and the initial second passivation stack 105 on the first region 130, appropriately reducing the reaction temperature of the first etching solution can also ensure the removal of the remaining initial second passivation stack 105 on the first region 130, or the removal of the second protective layer 108 and the initial second passivation stack 105 remaining on the first region 130.

[0077] In some cases, the reaction time of the first etching solution can be shorter than that of the second etching solution. Thus, compared with the reaction time of the second etching solution, by reducing the reaction time of the first etching solution, the probability of over-etching of the first protective layer 104 by the first etching solution can also be reduced, so as to improve the yield of the formed back contact battery. In addition, the first laser etching process has preliminarily etched the second protective layer 108 and the initial second passivation stack 105 on the first region 130. In the step of using the first etching solution to supplement the etching of the second protective layer 108 and the initial second passivation stack 105 on the first region 130, appropriately reducing the reaction time of the first etching solution can also ensure the removal of the remaining initial second passivation stack 105 on the first region 130, or the removal of the second protective layer 108 and the initial second passivation stack 105 remaining on the first region 130.

[0078] In some cases, both the first etchant and the second etchant can be potassium hydroxide solutions, and the concentration of potassium hydroxide in the first etchant is less than that in the second etchant. Thus, compared with the concentration of potassium hydroxide in the second etchant, by reducing the concentration of potassium hydroxide in the first etchant, the probability of over-etching the first protective layer 104 by the first etchant can also be reduced, so as to improve the yield of the formed back-contact battery. In addition, the first laser etching process has preliminarily etched the second protective layer 108 and the initial second passivation stack 105 located on the first region 130. In the step of supplementing the etching of the second protective layer 108 and the initial second passivation stack 105 located on the first region 130 with the first etchant, appropriately reducing the concentration of potassium hydroxide in the first etchant can also ensure the removal of the initial second passivation stack 105 remaining on the first region 130, or the removal of the second protective layer 108 and the initial second passivation stack 105 remaining on the first region 130.

[0079] It should be noted that in order to reduce the probability of over-etching the first protective layer 104 by the first etchant and improve the yield of the formed back-contact battery, it can be achieved by designing at least one of the reaction temperature, reaction time or the concentration of potassium hydroxide of the first etchant to be smaller than that of the second etchant. In other words, the above three cases can be designed selectively, or two of them can be designed selectively, or they can be designed simultaneously in the manufacturing method.

[0080] In some examples, both the step of using the first etchant and the step of using the second etchant can be realized by a tank-type alkaline polishing process. In the step of using the first etchant, the concentration of potassium hydroxide in the first etchant can be 2% - 10%, for example, it can be 3%, 4%, 5%, 6%, 7%, 8% or 9%, etc.; the reaction temperature can be lower than 80°C, for example, it can be 78°C, 75°C, 73°C, 70°C, 68°C, 65°C, 63°C or 60°C, etc.; the reaction time is 50s - 1000s, for example, it can be 100s, 200s, 300s, 400s, 500s, 600s, 700s, 800s or 900s, etc. The concentration in the second etchant can be 2% - 10%, for example, it can be 3%, 4%, 5%, 6%, 7%, 8% or 9%, etc.; the reaction temperature can be higher than or equal to 80°C, for example, it can be 80°C, 83°C, 85°C, 88°C, 90°C, 93°C, 95°C or 98°C, etc.; the reaction time is 50s - 1000s, for example, it can be 100s, 200s, 300s, 400s, 500s, 600s, 700s, 800s or 900s, etc.

[0081] In some cases, referring to Figure 4, in the step of forming the stacked structure 101, the second etching solution also etches the substrate 100 located in the second region 140. The surface of the substrate 100 located in the second region 140 is the second surface, and the surface of the substrate 100 located in the first region 130 is the first surface. Taking the first surface 110 as the reference plane, the second surface is lower than the first surface. On this basis, after performing step S6, with reference to Figure 4 and Figure 11 , the second passivation stack 115 located in the second region 140, that is, the second passivation stack 115 located on the second surface; the stacked structure 101 located in the first region 130, that is, the stacked structure 101 located on the first surface.

[0082] In some examples, with reference to Figure 11 , taking the first surface 110 as the reference plane, on the basis that the second surface is lower than the first surface, most regions of the second passivation stack 115 away from the surface of the substrate 100 are lower than the surface of the stacked structure 101 away from the substrate 100, and most regions of the doped amorphous silicon layer 117 in the second passivation stack 115 are staggered from the doped polysilicon layer 103 in the stacked structure 101 along the first direction X.

[0083] In some examples, with reference to Figure 4 , along the first direction X, the spacing between the second surface and the first surface can be 3 μm to 10 μm. For example, it can be 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, etc.

[0084] It should be noted that the spacing between the second surface and the first surface can be adjusted by adjusting the etching degree of the second etching solution on the substrate 100 located in the second region 140. On this basis, the designed spacing between the second surface and the first surface can be 3 μm to 10 μm. On the one hand, it is beneficial to avoid the spacing between the second surface and the first surface from being too small to ensure that there is a certain step difference between the second passivation stack 115 and the stacked structure 101, so as to ensure that most regions of the doped amorphous silicon layer 117 in the second passivation stack 115 are staggered from the doped polysilicon layer 103 in the stacked structure 101 along the first direction X; on the other hand, it is beneficial to avoid the spacing between the second surface and the first surface from being too large to avoid too large a step difference between the second passivation stack 115 and the stacked structure 101, thereby avoiding too large a concavo-convex difference on the back surface of the finally formed back contact battery, so as to improve the structural stability of the finally formed back contact battery.

[0085] The following details the first laser etching process and the second laser etching process.

[0086] In some embodiments, the laser used in the first laser etching process is the first laser, and the laser used in the second laser etching process is the second laser. The wavelength of the first laser can be less than the wavelength of the second laser.

[0087] It should be noted that with reference to Figure 4 or Figure 7 , before the first laser etching process, a stacked structure 101 has been formed on the first region 130; in combination with reference Figure 9 and Figure 10 , in the subsequent steps of the first laser etching process, if the energy generated when the first laser irradiates the first region 130 is too large or the penetration depth of the film layer on the first region 130 is too large, it is easy to cause relatively large laser damage to the stacked structure 101. On this basis, it is designed that the wavelength of the first laser can be less than the wavelength of the second laser, which is beneficial to reducing the penetration depth of the first laser to avoid relatively large laser damage to the stacked structure 101, thereby ensuring an excellent passivation effect of the first passivation stack 123 on the first region 130.

[0088] In some examples, the first laser is a purple laser, and the second laser can be a green laser. Among them, compared with the green laser, the purple laser has a smaller wavelength, a smaller penetration depth into the film layer, and the energy of the purple laser is more concentrated on the surface of the film layer, all of which are beneficial to reducing the probability of relatively large laser damage to the stacked structure 101 caused by the first laser.

[0089] It should be noted that both the purple laser and the green laser belong to picosecond lasers, and picosecond lasers are ultra-short pulse lasers. The purple laser can also refer to an ultraviolet picosecond laser, and the green laser can also refer to a green picosecond laser.

[0090] In some embodiments, a first laser is generated by a first laser device in the first laser etching process; a second laser is generated by a second laser device in the second laser etching process. On this basis, to avoid laser damage to the stacked structure 101 caused by the first laser, the laser scanning rate, power, or frequency of the first laser device can also be adjusted to avoid excessive energy generated when the first laser irradiates the first region 130.

[0091] In some cases, the laser scanning speed of the first laser device can be greater than the laser scanning speed of the second laser device. It should be noted that the size of the light spot irradiated on the film layer can be controlled by adjusting the laser scanning speed. Designing the laser scanning speed of the first laser device to be greater than the laser scanning speed of the second laser device is beneficial to reducing the size of the light spot irradiated by the first laser on the film layer, so as to reduce the probability of relatively large laser damage to the stacked structure 101 caused by the first laser.

[0092] In some examples, the laser scanning speed of the first laser can be 40 m / s to 60 m / s. For example, it can be 41 m / s, 42 m / s, 43 m / s, 44 m / s, 45 m / s, 46 m / s, 47 m / s, 48 m / s, 49 m / s, 50 m / s, 51 m / s, 52 m / s, 53 m / s, 54 m / s, 55 m / s, 56 m / s, 57 m / s, 58 m / s or 59 m / s, etc.; the laser scanning speed of the second laser can be 30 m / s to 50 m / s. For example, it can be 30 m / s, 31 m / s, 32 m / s, 33 m / s, 34 m / s, 35 m / s, 36 m / s, 37 m / s, 38 m / s, 39 m / s, 40 m / s, 41 m / s, 42 m / s, 43 m / s, 44 m / s, 45 m / s, 46 m / s, 47 m / s, 48 m / s or 49 m / s, etc.

[0093] In some cases, the power of the first laser can be less than the power of the second laser. It should be noted that the energy of the laser output by the laser can be controlled by adjusting the power of the laser. Designing the power of the first laser to be less than the power of the second laser is beneficial to reducing the energy of the first laser output by the first laser, so as to reduce the energy of the first laser irradiating on the film layer, and to reduce the probability of the first laser causing significant laser damage to the stacked structure 101.

[0094] In some examples, the power of the first laser can be 10 W to 30 W. For example, it can be 11 W, 12 W, 13 W, 14 W, 15 W, 16 W, 17 W, 18 W, 19 W, 20 W, 21 W, 22 W, 23 W, 24 W, 25 W, 26 W, 27 W, 28 W or 29 W, etc.; the power of the second laser can be 60 W to 80 W. For example, it can be 61 W, 62 W, 63 W, 64 W, 65 W, 66 W, 67 W, 68 W, 69 W, 70 W, 71 W, 72 W, 73 W, 74 W, 75 W, 76 W, 77 W, 78 W or 79 W, etc.

[0095] In some cases, the frequency of the first laser can be less than the frequency of the second laser. It should be noted that the overlapping rate of the light spots irradiated on the film layer can be controlled by adjusting the frequency of the laser. Designing the frequency of the first laser to be less than the frequency of the second laser is beneficial to reducing the overlapping rate of the light spots formed by the first laser on the film layer, and to reducing the probability of the first laser causing significant laser damage to the stacked structure 101.

[0096] In some examples, the frequency of the first laser can be from 900 kHz to 1100 kHz. For example, it can be 910 kHz, 920 kHz, 930 kHz, 940 kHz, 950 kHz, 960 kHz, 970 kHz, 980 kHz, 990 kHz, 1000 kHz, 1010 kHz, 1020 kHz, 1030 kHz, 1040 kHz, 1050 kHz, 1060 kHz, 1070 kHz, 1080 kHz, or 1090 kHz, etc.; the frequency of the second laser can be from 1100 kHz to 1300 kHz. For example, it can be 1110 kHz, 1120 kHz, 1130 kHz, 1140 kHz, 1150 kHz, 1160 kHz, 1170 kHz, 1180 kHz, 1190 kHz, 1200 kHz, 1210 kHz, 1220 kHz, 1230 kHz, 1240 kHz, 1250 kHz, 1260 kHz, 1270 kHz, 1280 kHz, or 1290 kHz, etc.

[0097] It should be noted that by combining the adjustment of the laser scanning speed and the frequency of the laser, the overlap rate of the light spots irradiated on the film layer can also be controlled.

[0098] In addition, to reduce the probability that the first laser causes significant laser damage to the stacked structure 101 compared to the second laser, it can be achieved by designing at least one of the laser scanning speed, power, or frequency of the first laser to be smaller. In other words, one of the above three situations can be selected for design, or two of them can be selected for design, or all three can be designed simultaneously in the manufacturing method.

[0099] In some examples, based on the design that at least one of the laser scanning speed, power, or frequency of the first laser is smaller than that of the second laser, when the first laser is a purple laser, the second laser can be a green laser or a purple laser.

[0100] In some embodiments, in combination with reference Figure 11 and Figure 12 , Figure 12 FIG. 18 is a partial cross-sectional schematic diagram after the pickling process in the manufacturing method of the back-contact battery provided by an embodiment of the present disclosure. After forming the second passivation stack 115, the manufacturing method of the back-contact battery may further include: using a pickling process to remove the second protective layer 108 located on the second region 140 and the first protective layer 104. In this way, it is beneficial to form the first gate line electrically connected to the doped polysilicon layer 103 on the first passivation stack 123 and the second gate line electrically connected to the doped amorphous silicon layer 117 on the second passivation stack 115.

[0101] It should be noted that before forming the first gate line and the second gate line, a transparent conductive film is first formed on the surface jointly formed by the first passivation stack 123 and the second passivation stack 115. The transparent conductive film is patterned, and the remaining transparent conductive film includes transparent conductive layers arranged alternately and spaced apart along the second direction Y. Subsequently, the first gate line and the second gate line are fabricated on the transparent conductive layers. Among them, a single transparent conductive layer is located on a single first region 130 or a single second region 140. In this way, there is a gap between adjacent transparent conductive layers, which helps to prevent the first gate line and the second gate line from short-circuiting.

[0102] In some embodiments, referring to Figure 9 , the material of the second protective layer 108 may include at least one of silicon oxide, silicon nitride, or silicon oxynitride.

[0103] In some embodiments, referring to Figure 4 , the material of the first protective layer 104 may include at least one of silicon oxide, silicon nitride, or silicon oxynitride.

[0104] In some examples, with reference to Figure 11 and Figure 12 , in the pickling process, a hydrofluoric acid solution can be used to remove the second protective layer 108 located on the second region 140 and the first protective layer 104.

[0105] In summary, before the first laser etching process, not only is the first protective layer 104 formed on the first region 130, but also the second protective layer 108 is formed on the side of the doped amorphous silicon film 107 away from the intrinsic amorphous silicon film 106. Then, on the premise of not causing laser damage and over-etching to the stack structure 101, the first laser etching process is first used to preliminarily etch the second protective layer 108 and the initial second passivation stack 105 located on the first region 130. Then, with the cooperation of the second protective layer 108 and the first protective layer 104 located on the second region 140, a first etching solution is used to supplement the etching of the second protective layer 108 and the initial second passivation stack 105 located on the first region 130, so as to ensure that in the finally formed back-contact battery, the stack structure 101 is only located in the first region 130 and the second passivation stack 115 is only located in the second region 140, which helps to reduce the series resistance of the finally formed back-contact battery and improve the fill factor of the back-contact battery, thereby improving the photoelectric conversion efficiency of the back-contact battery. Moreover, with the mutual cooperation of steps S2 to S6, it is beneficial to improve the stability of the manufacturing process of the back-contact battery and reduce the difference in the photoelectric conversion efficiency between different manufactured back-contact batteries, thereby improving the yield of the manufactured back-contact battery.

[0106] Another embodiment of the present disclosure also provides a back-contact battery, which is formed by the manufacturing method of the back-contact battery provided in the foregoing embodiment. The back-contact battery provided in another embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that the same or corresponding parts as those in the foregoing embodiment will not be described in detail herein.

[0107] Referring to Figure 12 , the back-contact battery includes: a substrate 100 having a first surface 110 and a second surface 120 opposite to each other in a first direction X. The second surface 120 includes a first region 130 and a second region 140 arranged alternately in a second direction Y. The first direction X is the thickness direction of the substrate 100, and the second direction Y intersects the first direction X; a stacked structure 101 located on the first region 130, the stacked structure 101 including a tunneling layer 102, a doped polysilicon layer 103, and a first protective layer 104 stacked in the first direction X; a second passivation stack 115 located on the second region 140, the second passivation stack 115 including an intrinsic amorphous silicon layer 116 and a doped amorphous silicon layer 117 stacked in the first direction X.

[0108] Another embodiment of the present disclosure also provides a back-contact stacked battery, which includes a back-contact battery formed by the manufacturing method of the back-contact battery provided in the foregoing embodiment, or the back-contact battery provided in the foregoing embodiment. The back-contact stacked battery provided in another embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that the same or corresponding parts as those in the foregoing embodiment will not be described in detail herein.

[0109] Referring to Figure 13 , Figure 13 is a partial cross-sectional schematic diagram of a back-contact stacked battery provided in another embodiment of the present disclosure. The back-contact stacked battery includes: a bottom cell 159, which is a back-contact battery formed by the manufacturing method of the back-contact battery provided in the foregoing embodiment, or the back-contact battery provided in the foregoing embodiment; a top cell 169, which is one of a perovskite battery, a donor-acceptor battery, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell. The top cell 169 is located on one side of the bottom cell 159.

[0110] In some embodiments, the top cell 169 may include: a stacked first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an antireflection layer. Among them, the first transport layer faces the bottom cell 159.

[0111] In some examples, the first transport layer may be one of an electron transport layer or a hole transport layer, and the second transport layer may be the other of an electron transport layer or a hole transport layer.

[0112] In some embodiments, the bandgap width of the top cell 169 is wider than that of the bottom cell 159. Therefore, stacking the top cell 169 above the bottom cell 159 can enable the tandem cell to have a wider spectral response range, thereby maximizing the utilization of solar energy and improving the efficiency of the solar cell.

[0113] In some embodiments, the bottom cell 159 further includes a first grid line electrically connected to the doped polysilicon layer 103, and a second grid line electrically connected to the doped amorphous silicon layer 117.

[0114] The connection manner of the top cell 169 and the bottom cell 159 will be described in detail below.

[0115] In some embodiments, referring to Figure 14 , Figure 14 FIG. is a schematic diagram of a connection manner between the top cell and the bottom cell in a back-contact tandem cell provided by another embodiment of the present disclosure. The top cell 169 and the bottom cell 159 can form a four-terminal tandem structure. The positive electrode and the negative electrode in the top cell 169 are respectively led out as independent terminals, and the first grid line and the second grid line in the bottom cell 159 are also respectively led out as independent terminals. In other words, in the four-terminal tandem structure, the top cell 169 and the bottom cell 159 can be independently fabricated. There is an optical connection between the top cell 169 and the bottom cell 159, and the circuits are independent of each other and output independently.

[0116] In this way, on the one hand, it is beneficial to avoid the limitation of the performance of the back-contact tandem cell by current matching, which is beneficial to maximizing the utilization rate of sunlight and the conversion efficiency, thereby obtaining a higher photoelectric conversion efficiency; on the other hand, through optical coupling between the top cell 169 and the bottom cell 159, there is no need to consider the process compatibility problem caused by the current matching between the top cell 169 and the bottom cell 159. The process is relatively simple. The production lines of the top cell 169 and the bottom cell 159 can be combined to be used for the preparation of the four-terminal tandem structure without separately modifying the existing production lines, thereby reducing the preparation cost of the back-contact tandem cell.

[0117] In other embodiments, referring to Figure 15 , Figure 15 FIG. is a schematic diagram of another connection manner between the top cell and the bottom cell in a back-contact tandem cell provided by another embodiment of the present disclosure. The top cell 169 and the bottom cell 159 can form a three-terminal tandem structure. The top cell 169 and the bottom cell 159 maintain good ohmic contact. One terminal is led out from the end of the top cell 169 far from the bottom cell 159, and the first grid line and the second grid line in the bottom cell 159 are respectively led out as two independent terminals.

[0118] Thus, the top cell 169 and the bottom cell 159 can be connected by directly depositing the top cell 169 on the bottom cell 159, without additional circuit design, which is beneficial to reducing the manufacturing cost of the photovoltaic module composed of the back-contact tandem cell. In addition, the three-terminal tandem structure composed of the top cell 169 and the bottom cell 159 does not need to consider current matching, which also means higher tolerance for the bandgap and thickness of the top cell 169.

[0119] It should be noted that there is a "minimum current limit" in the two-terminal tandem structure of a TOPCon cell or an HJT cell connected in series with a perovskite cell. The current of the two-terminal tandem structure is the minimum current of the two series-connected cells. Only when the currents of the two series-connected cells match or are close to matching, can the whole device operate at the maximum power. When there is a large current mismatch (for example, in the morning or evening when the sunlight color temperature is lower and the spectrum will shift), the power generation of the two-terminal tandem structure drops significantly. While the three-terminal tandem structure composed of a perovskite combined with a back-contact cell can output the mismatched current through an additional terminal, ensuring that the back-contact tandem cell can operate at a relatively higher power. Moreover, the voltage matching required in the three-terminal tandem structure is less affected by the change of the solar spectrum than the current, so the three-terminal tandem structure has a wider scene adaptability.

[0120] In still other embodiments, referring to Figure 16 , Figure 16 is a schematic diagram of another connection method between the top cell and the bottom cell in the back-contact tandem cell provided by another embodiment of the present disclosure. The top cell 169 and the bottom cell 159 can form a two-terminal tandem structure. The positive electrode in the top cell 169 is electrically connected to one of the first grid line and the second grid line in the bottom cell 159 to form one terminal, and the negative electrode in the top cell 169 is electrically connected to the other of the first grid line and the second grid line in the bottom cell 159 to form another terminal.

[0121] Another embodiment of the present disclosure provides a photovoltaic module, including a plurality of back-contact cells formed by the manufacturing methods of the back-contact cells provided in the foregoing embodiments, or a plurality of back-contact cells provided in the foregoing embodiments, or a plurality of back-contact tandem cells provided in the foregoing embodiments. It should be noted that the same or corresponding parts as those in the foregoing embodiments will not be described in detail here.

[0122] The photovoltaic module includes: a battery string, which is formed by connecting back-contact cells formed by the manufacturing methods of the back-contact cells provided in the foregoing embodiments, or by connecting a plurality of back-contact cells provided in the foregoing embodiments, or by connecting a plurality of back-contact tandem cells provided in the foregoing embodiments; an encapsulation film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulation film facing away from the battery string.

[0123] Those of ordinary skill in the art can understand that the above embodiments are specific examples for implementing the present disclosure. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be subject to the scope defined by the claims.

Claims

1. A manufacturing method of a back contact battery, characterized in that, Comprising: Providing a substrate having a first surface and a second surface opposite to each other in a first direction, the second surface including a first region and a second region alternately arranged in a second direction, the first direction being the thickness direction of the substrate, and the second direction intersecting the first direction; Forming a stacked structure on the first region, the stacked structure including a tunneling layer, a doped polysilicon layer, and a first protective layer stacked along the first direction; Forming an initial second passivation stack on the surface jointly formed by the second surface and the stacked structure, the initial second passivation stack including an intrinsic amorphous silicon film and a doped amorphous silicon film stacked along the first direction; Forming a second protective layer on a side of the doped amorphous silicon film away from the intrinsic amorphous silicon film; Using a first laser etching process to etch the second protective layer and the initial second passivation stack located on the first region, and part of the initial second passivation stack, or part of the second protective layer and part of the initial second passivation stack remain on the first region; Using the second protective layer located on the second region as an etching stop layer and the first protective layer as an etching stop layer, and using a first etching solution to remove the initial second passivation stack remaining on the first region, or remove the second protective layer and the initial second passivation stack remaining on the first region, and the remaining initial second passivation stack located on the second region is the second passivation stack, and the tunneling layer and the doped polysilicon layer constitute the first passivation stack.

2. The manufacturing method of the back contact battery according to claim 1, characterized in that, After forming the stacked structure and before forming the initial second passivation stack, the manufacturing method of the back contact battery further includes: Texturing the first surface to convert the first surface into a textured surface; Forming a passivation and antireflection layer on the textured surface; Wherein, the process temperature used in the step of forming the passivation and antireflection layer is a first temperature, and the process temperature used in the step of forming the second protective layer is a second temperature, and the first temperature is greater than or equal to the second temperature.

3. The manufacturing method of the back-contact battery according to claim 2, characterized in that, The second temperature is 150°C to 250°C.

4. The manufacturing method of the back-contact battery according to claim 2, characterized in that, The step of forming the passivation and antireflection layer includes: Using a first deposition process to form an aluminum oxide film on the textured surface, and the aluminum oxide film is also formed on a partial region of the second surface and on a side surface connecting the first surface and the second surface; Using a second deposition process to form a silicon nitride film on a side of the aluminum oxide film away from the substrate; Using a chain etching process to remove the silicon nitride film located on a partial region of the second surface and the side surface, and the remaining silicon nitride film located on the first surface is the silicon nitride layer; Using the silicon nitride layer as an etching stop layer and using a third etching solution to remove the aluminum oxide film located on a partial region of the second surface and the side surface, and the remaining aluminum oxide film located on the first surface is the aluminum oxide layer, and the passivation and antireflection layer includes the aluminum oxide layer and the silicon nitride layer.

5. The manufacturing method of the back-contact battery according to claim 1, characterized in that, The step of forming the stacked structure includes: Forming an initial stacked structure on the second surface, the initial stacked structure including a tunneling film, a doped polysilicon film, and a first protective film stacked along the first direction; Using a second laser etching process, the initial stacked structure located on the second region is preliminarily etched to remove a part of the thickness of the initial stacked structure, and the initial stacked structure with at least a part of the thickness is subjected to laser modification treatment; Using a second etching solution, the remaining initial stacked structure located on the second region is removed. The remaining initial stacked structure located on the first region is the stacked structure, the remaining tunneling film located on the first region is the tunneling layer, the remaining doped polysilicon film located on the first region is the doped polysilicon layer, and the remaining first protective film located on the first region is the first protective layer.

6. The manufacturing method of the back-contact battery according to claim 5, characterized in that, The reaction temperature of the first etching solution is lower than that of the second etching solution; and / or, the reaction time of the first etching solution is shorter than that of the second etching solution; and / or, both the first etching solution and the second etching solution are potassium hydroxide solutions, and the concentration of potassium hydroxide in the first etching solution is lower than that in the second etching solution.

7. The manufacturing method of the back contact battery according to claim 5, characterized in that, In the step of forming the stacked structure, the second etching solution also etches the substrate located in the second region. The surface of the substrate located in the second region is the second surface, and the surface of the substrate located in the first region is the first surface. Taking the first surface as the reference surface, the second surface is lower than the first surface.

8. The manufacturing method of the back-contact battery according to claim 7, characterized in that, In the first direction, the distance between the second surface and the first surface is 3 μm to 10 μm.

9. The manufacturing method of the back contact battery according to claim 5, characterized in that, The laser used in the first laser etching process is the first laser, and the laser used in the second laser etching process is the second laser. The wavelength of the first laser is shorter than that of the second laser.

10. The manufacturing method of the back-contact battery according to claim 5, characterized in that, The first laser is generated by a first laser device in the first laser etching process; the second laser is generated by a second laser device in the second laser etching process; Wherein, the laser scanning speed of the first laser device is greater than that of the second laser device; and / or, the power of the first laser device is lower than that of the second laser device; and / or, the frequency of the first laser device is lower than that of the second laser device.

11. The manufacturing method of the back-contact battery according to claim 10, characterized in that, The laser scanning speed of the first laser device is 40 m / s to 60 m / s, and the laser scanning speed of the second laser device is 30 m / s to 50 m / s; and / or, the power of the first laser device is 10 W to 30 W, and the power of the second laser device is 60 W to 80 W; and / or, the frequency of the first laser device is 900 kHz to 1100 kHz, and the frequency of the second laser device is 1100 kHz to 1300 kHz.

12. The manufacturing method of the back-contact battery according to claim 1, wherein, After forming the second passivation stack, the manufacturing method of the back contact battery further includes: Using an acid pickling process to remove the second protective layer located on the second region and the first protective layer.

13. A back-contact battery, characterized in that, The back contact battery is the back contact battery formed by the manufacturing method of the back contact battery according to any one of claims 1 to 12.

14. A back-contact stacked cell, characterized in that, Including: The bottom cell, which is a back-contact cell formed by the manufacturing method of the back-contact cell according to any one of claims 1 to 12, or is the back-contact cell according to claim 13; The top cell, which is one of a perovskite cell, a donor-acceptor cell, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell, and the top cell is located on one side of the bottom cell.

15. A photovoltaic module, characterized in that, Comprising: A battery string, which is formed by connecting multiple back-contact cells formed by the manufacturing method of the back-contact cell according to any one of claims 1 to 12, or multiple back-contact cells according to claim 13, or is formed by connecting multiple back-contact stacked cells according to claim 14; An encapsulation film, which is used to cover the surface of the battery string; A cover plate, which is used to cover the surface of the encapsulation film facing away from the battery string.

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