Method for producing a photovoltaic cell, photovoltaic cell, stacked cell and photovoltaic module

Abstract

The application relates to a preparation method of a photovoltaic cell, the photovoltaic cell, a laminated cell and a photovoltaic module. The preparation method of the photovoltaic cell comprises the following steps: providing a substrate, performing functional layer preparation on the substrate to form a cell intermediate body, wherein a surface passivation layer is arranged on the cell intermediate body, and the surface passivation layer is provided with a windowed area; depositing a first seed layer on the surface passivation layer and performing annealing treatment on the first seed layer; depositing a second seed layer on the first seed layer subjected to the annealing treatment; electroplating to obtain an electroplated material layer on the second seed layer; and etching to remove the first seed layer, the second seed layer and parts of the electroplated material layer except the windowed area, so as to obtain an electrode layer, thereby forming the photovoltaic cell. The preparation method of the photovoltaic cell can reduce the limitation of the preparation process of the photovoltaic cell.

Description

Technical Field

[0001] This application relates to the field of photovoltaic cell technology, and in particular to a method for preparing a photovoltaic cell, a photovoltaic cell, a tandem cell, and a photovoltaic module. Background Technology

[0002] With the continuous development of science and technology, photovoltaic cells have been widely used in people's daily lives due to their environmental friendliness, economy and reliability. Photovoltaic cells mainly consist of a substrate and an electrode structure. In order to ensure the ohmic contact characteristics between the electrode and the light absorption layer, and to simultaneously improve the carrier collection efficiency and the conductivity and adhesion of the electrode, a seed layer is required to lay the foundation for subsequent electrode preparation.

[0003] Currently, in the process of solar cell fabrication, PVD (Physical Vapor Deposition) is commonly used to prepare composite seed layer structures. For example, the composite seed layer includes an aluminum-silicon alloy layer, a titanium-tungsten alloy layer, and a copper layer. The titanium-tungsten alloy layer acts as a diffusion barrier layer to prevent copper atoms from penetrating downwards and affecting the electrical performance of the photovoltaic cell. However, the titanium-tungsten alloy layer is expensive, and the complex composite seed layer structure leads to a complicated fabrication process. Therefore, the current photovoltaic cell fabrication process has significant limitations. Summary of the Invention

[0004] Therefore, it is necessary to provide a method for preparing photovoltaic cells, photovoltaic cells, tandem cells, and photovoltaic modules that reduces the limitations of photovoltaic cell preparation processes, in order to address the aforementioned technical problems.

[0005] In a first aspect, this application provides a method for preparing a photovoltaic cell, comprising:

[0006] A substrate is provided, and a functional layer is prepared on the substrate to form a battery intermediate, wherein a surface passivation layer is disposed on the battery intermediate, and the surface passivation layer is provided with a window area;

[0007] A first seed layer is deposited on the surface passivation layer, and the first seed layer is annealed.

[0008] A second seed layer is deposited on the annealed first seed layer;

[0009] An electroplating material layer is obtained by electroplating on the second seed layer;

[0010] Etching removes portions of the first seed layer, the second seed layer, and the electroplated material layer, excluding the windowed area, to obtain the electrode layer.

[0011] Secondly, this application also provides a photovoltaic cell, which is prepared using the photovoltaic cell preparation method described above, comprising:

[0012] Substrate;

[0013] A doped semiconductor layer is located on the back side of the substrate;

[0014] A surface passivation layer is located on the side of the doped semiconductor layer away from the back side, and the surface passivation layer is provided with a window area;

[0015] A composite seed layer, comprising a first seed layer and a second seed layer, wherein the first seed layer is located within the windowed region and the second seed layer is located on the side of the first seed layer away from the doped semiconductor layer;

[0016] The electrode layer is located on the side of the second seed layer that is away from the first seed layer.

[0017] Thirdly, this application also provides a stacked battery, the stacked battery including a top battery, an intermediate connecting layer and a bottom battery, the intermediate connecting layer being connected between the top battery and the bottom battery;

[0018] The top cell is one of a perovskite cell, a cadmium telluride photovoltaic cell, a copper indium gallium selenide photovoltaic cell, or a gallium arsenide photovoltaic cell, and the bottom cell is one of the aforementioned photovoltaic cells.

[0019] Fourthly, this application also provides a photovoltaic module, the photovoltaic module comprising a first cover plate, a first encapsulating film, a battery string, a second encapsulating film and a second cover plate stacked together; the battery string comprises a plurality of electrically connected photovoltaic cells, the photovoltaic cells being the photovoltaic cells described above, or the battery string comprising the stacked cells described above.

[0020] The aforementioned method for fabricating photovoltaic cells, photovoltaic cells, tandem cells, and photovoltaic modules first provides a substrate, and then fabricates a functional layer on the substrate to form a cell intermediate. The cell intermediate has a surface passivation layer, which includes a windowed area penetrating the passivation layer. Next, a first seed layer is deposited on the passivation layer, and the first seed layer is annealed. Then, a second seed layer is deposited on the annealed first seed layer. Finally, an electroplated material layer is obtained by electroplating on the second seed layer. Finally, the portions of the first seed layer, the second seed layer, and the electroplated material layer, excluding the windowed areas, are removed by etching to obtain... An electrode layer is used to form a photovoltaic cell. After depositing the first seed layer on the surface passivation layer, the first seed layer is annealed, which gives it the corresponding diffusion barrier capability, preventing the metal in the second seed layer from penetrating into the substrate functional layer. Therefore, there is no need to set a diffusion barrier layer in the seed layer preparation process. The purpose of replacing the composite seed layer structure with a double seed layer structure composed of the first and second seed layers can be achieved. At the same time, compared with the traditional physical vapor deposition process, the above preparation process only involves two seed layer depositions, one annealing and electroplating film thickness, which reduces the complexity of parameter control for multiple PVD depositions, thereby improving the process efficiency. Overall, it reduces the limitations of photovoltaic cell preparation process. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic flowchart of a photovoltaic cell fabrication method in one embodiment;

[0023] Figure 2 This is a schematic diagram of the flow of photovoltaic cells in the fabrication equipment of a photovoltaic cell fabrication method in one embodiment;

[0024] Figure 3 This is a flowchart illustrating the manufacturing process of a conventional photovoltaic cell in one embodiment.

[0025] Figure 4 This is a process flow diagram of an improved photovoltaic cell fabrication method in one embodiment;

[0026] Figure 5 This is a schematic flowchart of a photovoltaic cell fabrication method in another embodiment;

[0027] Figure 6 This is a side view of the photovoltaic cell provided in another embodiment before etching;

[0028] Figure 7 A top view of the photovoltaic cell provided in another embodiment before etching;

[0029] Figure 8 This is a side view of the photovoltaic cell after etching, provided in another embodiment;

[0030] Figure 9 This is a top view of the photovoltaic cell provided in another embodiment after etching.

[0031] Figure label:

[0032] 11-Substrate;

[0033] 12-Doped semiconductor layer;

[0034] 13-Surface passivation layer;

[0035] 14 - Window opening area;

[0036] 15-Composite seed layer;

[0037] 151 - First seed layer;

[0038] 152 - Second seed layer;

[0039] 16-Electrode layer. Detailed Implementation

[0040] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0041] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0042] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0043] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0044] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0045] First, it should be understood that mainstream photovoltaic cells currently employ PVD (Physical Vapor Deposition) technology to fabricate composite seed layer structures. These structures provide an initial interface for subsequent metal deposition, guiding uniform growth and improving adhesion. PVD is a technology that, in a vacuum environment, physically transforms solid or liquid materials into gaseous atoms, molecules, or ions, which are then deposited onto a substrate surface to form a film. For example, in one feasible implementation, the composite seed layer comprises an aluminum-silicon alloy layer, a titanium-tungsten alloy layer, and a copper layer. The aluminum-silicon alloy layer directly contacts the silicon substrate, enhancing the seed layer structure. To improve adhesion between the aluminum-silicon alloy and the silicon substrate and provide diffusion barrier capabilities, aluminum-silicon alloy can be directly deposited onto the silicon substrate surface via magnetron sputtering to obtain an aluminum-silicon alloy layer of 50nm~200nm. A titanium-tungsten alloy layer serves as an intermediate barrier layer, preventing subsequent copper atom diffusion into the silicon substrate while enhancing adhesion to the upper copper layer. The titanium-tungsten alloy layer is deposited by continuous sputtering on top of the aluminum-silicon alloy layer, with a thickness of 50nm~100nm. The copper layer serves as the top conductive layer, providing a conductive layer for subsequent thick copper electroplating. To provide a uniform current distribution, the copper layer can be deposited by sputtering pure copper onto a titanium-tungsten alloy layer, with a thickness ranging from 100 nm to 300 nm. It's understandable that existing composite seed layer structures require a titanium-tungsten alloy layer as a copper diffusion barrier, acting as a buffer layer between the aluminum-silicon alloy layer and the copper layer, and also as a barrier against copper diffusion. This material has high resistivity and is costly. However, without the titanium-tungsten alloy layer, copper and aluminum-silicon alloys will interdiffuse during the annealing stage, causing deep-level defects in the battery, and the resulting stubborn alloy... Furthermore, residues are easily left during subsequent cleaning. On the other hand, the steps for preparing the composite seed layer structure involve first depositing an aluminum-silicon alloy layer, then annealing it after exiting the cavity, and finally depositing a copper layer. During this process, the aluminum-silicon alloy will oxidize outside the cavity, resulting in poor adhesion between the copper and the aluminum-silicon alloy. In summary, the currently prepared composite seed layer structure includes a titanium-tungsten alloy layer, which is expensive. Moreover, the complex composite seed layer structure formed by uniform deposition and annealing will lead to a complex preparation process. Therefore, the above-mentioned defects reflect the significant limitations of the current photovoltaic cell preparation process.

[0046] Therefore, this embodiment provides a method for preparing photovoltaic cells to solve the above-mentioned technical problems.

[0047] like Figure 1 As shown, a method for preparing solar energy is provided, including steps 202 to 210:

[0048] Step 202: Provide a substrate, and prepare a functional layer on the substrate to form a battery intermediate, wherein a surface passivation layer is provided on the battery intermediate, and the surface passivation layer is provided with a window area.

[0049] Step 204: Deposit a first seed layer on the surface passivation layer and anneal the first seed layer;

[0050] Step 206: Deposit a second seed layer on the annealed first seed layer;

[0051] Step 208: Electroplating is performed on the second seed layer to obtain an electroplating material layer;

[0052] Step 210: Etch away the portion of the first seed layer, the second seed layer, and the electroplated material layer except for the windowed area to obtain the electrode layer, thereby forming a photovoltaic cell.

[0053] It should be noted that the substrate is the basic material for fabricating photovoltaic cells and can be made of monocrystalline or polycrystalline materials, specifically silicon substrate, silicon carbide substrate, and gallium arsenide substrate, etc. The thickness of the substrate can be [missing information]. (include and Functional layers are fabricated on a substrate to achieve specific functions. Specifically, functional layers can be fabricated on the front side or the back side of the substrate. For example, in one feasible approach, a 100nm~200nm (inclusive) amorphous silicon film layer can be deposited on the back side of the substrate using low-pressure chemical vapor deposition technology. Battery intermediates characterize intermediate products in the photovoltaic cell manufacturing process. Surface passivation layers refer to insulating film layers deposited on the semiconductor surface to reduce surface defects and provide stable electrical performance.

[0054] It should be noted that after forming the surface passivation layer and setting the window area on the surface passivation layer, a new preparation process can be used to prepare the composite seed layer. First, a first seed layer can be deposited on the surface passivation layer. The first seed layer represents the first layer of material deposited on the surface passivation layer. The deposition method of the first seed layer can be physical vapor deposition, chemical vapor deposition, atomic layer deposition, etc. After the first seed layer is deposited, the first seed layer can be annealed to improve the pull-out force between the first seed layer and the substrate, thereby reducing the diffusion risk caused by high temperature. The annealing process parameters for the first seed layer can be adaptively set based on the preparation requirements. For example, in one feasible method, the annealing temperature for the first seed layer can be 300℃-500℃ (inclusive), the annealing time can be 1h~2h (inclusive), and the heating rate can be 5℃ / min~20℃ / min (inclusive).

[0055] It should be noted that after the annealing treatment of the first seed layer is completed, a second seed layer can be deposited on the first seed layer. The second seed layer represents the second layer of material deposited on the surface passivation layer. The deposition method can be the same as or different from the deposition method of the first seed layer. This embodiment will not be described in detail here.

[0056] It should be noted that the electroplated material layer is a material layer deposited on the second seed layer through an electroplating process. It can be understood that obtaining an electroplated material layer through electroplating can improve the conductivity of solar cells, enhance adhesion, and improve the barrier ability against metal diffusion. Etching refers to the technique of removing the material layer through physical or chemical means; specific etching methods can include wet etching and dry etching. The electrode layer obtained through etching is used to achieve electrical connections and charge collection. The electrode layer refers to the metal layer retained in the windowed area and its surrounding area through the etching process.

[0057] It should be noted that the windowed area refers to an opening region formed on the surface passivation layer through a specified process, facilitating electrical contact in subsequent fabrication processes. The specified process can specifically be laser grooving or etching. The specific shape of the windowed area can be adapted based on different cell types. Specifically, the windowed area can be elongated. It is understood that setting the shape of the windowed area to elongated can increase the contact area between the electrode and the functional layer, thereby reducing current loss during transmission. This is suitable for conventional photovoltaic cells. For example, in one feasible embodiment, the length of the windowed area can be... (Including the endpoints), the width of the surface passivation layer can be 178. Therefore, the width of the window area is usually set shorter than the width of the surface passivation layer, specifically 174. 175 Or 176 The windowed area can also be grid-shaped. It is understood that setting the shape of the windowed area to a grid shape allows for current collection from multiple directions, making it suitable for high-density current batteries. For example, in one feasible embodiment, the shape of the windowed area is a grid formed by alternating horizontal and vertical stripes, and the spacing between points within the windowed area can be the same or different. The windowed area can also be dot-shaped. It is understood that setting the shape of the windowed area to a dot-shaped shape maximizes the preservation of the surface area of ​​the surface passivation layer, thereby reducing surface recombination losses, making it suitable for high-efficiency crystalline silicon batteries. The arrangement of the windowed areas is not limited in this embodiment; specifically, it can be a parallel equidistant arrangement, a gradually denser arrangement from the center region of the substrate to the edge region, or a staggered arrangement, etc.

[0058] As an example, a silicon substrate is first provided as a substrate, and then a functional layer is prepared on the back side of the silicon substrate. A surface passivation layer is deposited on the back side of the silicon substrate, and part of the material is removed from the surface passivation layer by etching to obtain a windowed area, thereby forming a cell intermediate. A first seed layer is deposited on the surface passivation layer using physical vapor deposition, and after the first seed layer is deposited, it is annealed. After the first seed layer is annealed, a second seed layer is deposited on the first seed layer using physical vapor deposition. An electroplating material layer is obtained by electroplating on the second seed layer. The portion other than the first seed layer, the second seed layer, and the electroplating material layer is removed by wet etching to obtain an electrode layer, thereby forming a photovoltaic cell.

[0059] It is understandable that the photovoltaic cells described above can be prepared using conventional equipment according to the above-described process, or they can be prepared using integrated equipment according to the above-described process.

[0060] In one feasible approach, a silicon substrate is provided as the base. After the functional layer is fabricated to form a battery intermediate, high-temperature annealing is performed. The specific process for fabricating the functional layer can be as follows: a laser is used to open the insulating passivation layer of silicon nitride or aluminum oxide + silicon nitride in the N and P regions; then, a step-by-step process of coating and annealing is adopted, using integrated equipment, to first perform a coating process of aluminum-silicon alloy seed layer (first seed layer), and then enter the annealing chamber to improve the pull-out force between the aluminum-silicon alloy and the battery base. Then, a copper seed layer (second seed layer) coating process is performed; then, a window is opened on the insulating layer using photolithography to expose the area where the electrode needs to be fabricated. Functional ink is coated in the opened area, and copper electrodes are electroplated on the exposed seed layer as the base to obtain an electroplated material layer; then, the seed layer in the non-electrode area is etched, that is, the aluminum-silicon alloy layer, copper layer, and electroplated material layer except for the opened area are etched away to obtain the electrode layer to form a photovoltaic cell; finally, the prepared photovoltaic cell is tested.

[0061] Reference Figure 2 , Figure 2To illustrate the flow diagram of photovoltaic cells in the fabrication process equipment, specifically, after the material passes through the buffer zone, the first seed layer is deposited, and then after passing through the first temperature buffer zone, the first seed layer undergoes annealing. The fabrication process equipment is equipped with an annealing chamber buffer device, in which multiple carrier plates are stacked sequentially. The annealing chamber buffer device ensures sufficient carrier plate buffer space to improve production capacity and match the production capacity requirements of the preceding and following processes. The fabrication process equipment has carrier plate coding identification and recording functions and process monitoring functions. According to the program-set time, it performs the exit action from the chamber, and then after passing through the second temperature buffer zone, the second seed layer is deposited on the first seed layer. Finally, after passing through the buffer zone, the material is unloaded. The first temperature buffer zone and the second temperature buffer zone are temperature buffer zones established before and after the annealing chamber of the fabrication process equipment, respectively, to ensure the temperature stability of the annealing chamber and reduce temperature disturbances.

[0062] Understandably, referring to Figure 3 , Figure 3 This is a flow chart of the traditional photovoltaic cell manufacturing process. Specifically, an aluminum-silicon alloy layer, a titanium-tungsten alloy layer, and a copper layer are uniformly deposited on a substrate, followed by annealing, coating with functional inks, and electroplating with copper. (Refer to...) Figure 4 , Figure 4 The flowchart illustrates the improved photovoltaic cell fabrication process. Specifically, an aluminum-silicon alloy layer is first deposited on the substrate, followed by a copper layer after annealing of the aluminum-silicon alloy layer, and then functional ink and electroplated copper are applied. Thus, the photovoltaic cell fabrication process provided in this embodiment reduces film resistivity, improves electrode ohmic contact, increases fill factor (FF), enhances carrier collection capability, and increases current density by removing the titanium-tungsten alloy material, thereby improving fabrication efficiency while reducing production costs. Furthermore, optimizing the deposition and annealing process sequence reduces the risk of copper diffusion caused by high temperatures and eliminates the need for the titanium-tungsten alloy layer as a functional film layer for the copper layer. Moreover, if the deposition and annealing processes can be integrated into a single device, the process objectives of depositing the aluminum-silicon alloy layer, annealing, depositing the copper layer, and improving the deposition and adhesion of the seed layer can be achieved simultaneously by setting the cavity function and sequence, while meeting the requirements of both deposition and annealing processes.

[0063] The above-described photovoltaic cell fabrication method involves providing a substrate and fabricating a functional layer on the substrate to form a cell intermediate. The intermediate has a surface passivation layer, which includes a windowed area penetrating the passivation layer. A first seed layer is then deposited on the passivation layer and annealed. A second seed layer is then deposited on the annealed first seed layer. An electroplated material layer is then obtained on the second seed layer. Finally, the portions of the first seed layer, the second seed layer, and the electroplated material layer, excluding the windowed areas, are removed by etching to obtain an electrode layer, thus forming a photovoltaic cell. Since the first seed layer is deposited on the passivation layer, ... Annealing the first seed layer endows it with diffusion barrier capabilities, preventing the metal in the second seed layer from penetrating into the substrate functional layer. This eliminates the need for a diffusion barrier layer during seed layer fabrication, allowing the dual-layer seed layer structure (comprising the first and second seed layers) to replace the composite seed layer structure. Furthermore, compared to traditional physical vapor deposition (PVD) processes, this fabrication process involves only two seed layer depositions, one annealing step, and electroplating to achieve the desired film thickness. This reduces the complexity of parameter control in multiple PVD depositions, thereby improving process efficiency. Overall, this reduces the limitations of photovoltaic cell fabrication processes.

[0064] In one embodiment, refer to Figure 5 The battery intermediate includes a back-contact battery precursor; a functional layer is fabricated on a substrate to form the battery intermediate, including steps 302 to 306:

[0065] Step 302: Form a doped semiconductor layer on the back side of the substrate;

[0066] Step 304: Deposit a surface passivation layer on the side of the doped semiconductor layer away from the substrate;

[0067] Step 306: Laser-assisted opening of the surface passivation layer to obtain the back contact battery precursor.

[0068] It should be noted that various types of photovoltaic cells can be fabricated during the process of photovoltaic cell preparation, such as monocrystalline silicon photovoltaic cells, polycrystalline silicon photovoltaic cells, and back-contact cells. Among them, back-contact cells refer to cells in which the positive and negative electrodes are concentrated on the back side of the substrate. Compared with traditional cells, they have better carrier collection efficiency. The back-contact cell precursor represents the intermediate state of the back-contact photovoltaic cell after the back functional layer is prepared, such as the BC cell precursor. A PN junction can be formed by doping the semiconductor layer. After depositing a surface passivation layer on the side of the doped semiconductor layer away from the substrate, since the positive and negative electrodes of the back-contact cell are both located on the back side, the passivation effect of the surface passivation layer can be improved by high-temperature annealing and then laser delamination, thereby improving the carrier collection efficiency.

[0069] As an example, a doped semiconductor layer is obtained by doping the back side of a substrate with a specified material (e.g., P or B). A surface passivation layer is then deposited on the side of the doped semiconductor layer away from the substrate using chemical vapor deposition (PECVD). After the surface passivation layer is deposited, it undergoes high-temperature annealing, followed by laser delamination to obtain the back-contact cell precursor. PECVD, or Plasma-Enhanced Chemical Vapor Deposition, is a film deposition technique that utilizes plasma to activate chemical reactions. This approach not only allows for the fabrication of functional layers on the back side of the substrate through material doping and deposition processes but also enhances the stability of the film layer through high-temperature annealing, thereby improving the electrical performance of the fabricated photovoltaic cell. Therefore, this method not only lays the foundation for reducing the limitations of photovoltaic cell fabrication processes but also for improving the fabrication efficiency of photovoltaic cells.

[0070] In one embodiment, depositing a second seed layer on an annealed first seed layer includes:

[0071] Staged film deposition is performed on the surface of the first seed layer until the second seed layer is obtained.

[0072] It should be noted that due to the complex characteristics of back-contact batteries, specifically, they have structural characteristics such as fine electrode patterns, high requirements for interlayer bonding, and sensitivity to large-area uniformity. Therefore, in addition to depositing the second seed layer in one step, the second seed layer can also be deposited in stages by adjusting the process parameters to adapt to the special structural requirements of back-contact batteries. For example, in one feasible approach, a Cu layer can be deposited in the first stage with a power of 45W and a process parameter of 0.4nm / s. Then, when the actual thickness of the Cu layer reaches the first thickness value, the second stage of deposition can be started, that is, the Cu layer can continue to be deposited with a power of 100W and a process parameter of 3nm / s. Then, when the actual thickness of the Cu layer reaches the second thickness value, the third stage of deposition can be started, that is, the Cu layer can continue to be deposited with a power of 60W and a process parameter of 1nm / s, until a Cu layer of 250nm is deposited. In this way, by adopting a staged deposition process, depositing the second seed layer on the first seed layer, the material accumulation problem caused by rapid deposition can be avoided. Furthermore, by precisely controlling the deposition process parameters at each stage, both deposition efficiency and the performance of the deposited second seed layer can be taken into account. Therefore, this not only lays the foundation for reducing the limitations of photovoltaic cell fabrication processes but also lays the foundation for improving the fabrication effect of photovoltaic cells.

[0073] In one embodiment, the first seed layer is made of an alloy material, the second seed layer is made of a metallic material, and the first thickness of the first seed layer is less than the second thickness of the second seed layer.

[0074] It should be noted that the first seed layer is made of an alloy material, which can improve the bonding ability between the seed layer structure and the substrate, thereby reducing the contact resistance between them. The second seed layer can be made of a metal material, which can improve the conductivity of the seed layer structure, thus providing a reliable substrate for subsequent electroplating. The first thickness of the first seed layer is set to be less than the second thickness of the second seed layer. Since the first and second seed layers can adopt their respective suitable deposition methods, the fabrication efficiency and performance of the photovoltaic cell can be balanced. For example, in one feasible embodiment, assuming the photovoltaic cell is a back-contact cell, the first seed layer is made of an alloy material, which can improve the interfacial bonding ability of the back-contact cell, while the second seed layer can be made of a pure metal material, thereby ensuring the high conductivity and high compatibility requirements of the back-contact cell compared to other photovoltaic cells.

[0075] As an example, the first seed layer is made of aluminum-silicon alloy, the second seed layer is made of Cu material, and the first thickness of the first seed layer is [missing information]. The second thickness of the second seed layer is .

[0076] In one feasible approach, the first thickness is... The second thickness is , and satisfy: , .

[0077] It is understandable that the first thickness Second thickness By controlling the thickness within the corresponding range, the fabrication efficiency and performance of back-contact batteries can be balanced to the greatest extent.

[0078] As an example, the first thickness for Second thickness for .

[0079] As another example, the first thickness for Second thickness for .

[0080] As another example, the first thickness for Second thickness for .

[0081] As another example, the first thickness for Second thickness for .

[0082] As another example, the first thickness for Second thickness for .

[0083] In one feasible embodiment, the first seed layer comprises at least one of an aluminum-silicon alloy, an aluminum-copper alloy, an aluminum-titanium alloy, a nickel-vanadium alloy, and a copper-silicon alloy, and the second seed layer comprises at least one of copper, aluminum, nickel, and silver.

[0084] Understandably, based on the actual needs of the preparation, different alloy materials can be used to prepare the first seed layer, and different metal materials can be used to prepare the second seed layer. This can further reduce the limitations of the current photovoltaic cell preparation process by expanding the types of deposition materials for the first and second seed layers.

[0085] As an example, the alloy material for preparing the first seed layer is an aluminum-silicon alloy, and the metal material for preparing the second seed layer is copper.

[0086] As another example, the alloy material for preparing the first seed layer is an aluminum-silicon alloy, and the metal material for preparing the second seed layer is silver.

[0087] As another example, the alloy material for preparing the first seed layer is an aluminum-copper alloy, and the metal material for preparing the second seed layer is copper and silver.

[0088] As another example, the alloy materials for preparing the first seed layer are aluminum-silicon alloy and aluminum-copper alloy, and the metal material for preparing the second seed layer is copper.

[0089] It is understandable that when the metal material of the second seed layer includes two or more metal materials, the prepared second seed layer is a stacked structure composed of multiple metal materials. For example, assuming that the metal material for preparing the second seed layer is copper and silver, the second seed layer includes a second seed layer structure a made of copper and a second seed layer structure b made of silver. When the alloy material of the first seed layer includes two or more alloy materials, the first seed layer is also a stacked structure. For example, assuming that the metal material for preparing the first seed layer is aluminum-silicon alloy and aluminum-copper alloy, the first seed layer includes a first seed layer structure c made of aluminum-silicon alloy and a first seed layer structure d made of aluminum-copper alloy.

[0090] In one embodiment, depositing a first seed layer on the surface passivation layer includes:

[0091] An initial seed layer is deposited on the surface passivation layer; under vacuum, a predetermined proportion of doping elements are introduced into the initial seed layer to obtain the first seed layer.

[0092] It should be noted that during the deposition of the first seed layer, the first seed layer obtained can be made entirely of the aforementioned alloy material. However, considering the surface defects and carrier recombination of the seed layer, element doping can be performed under vacuum conditions during the deposition of the first seed layer to improve its performance.

[0093] As an example, an aluminum-silicon alloy is deposited in the first seed layer using chemical vapor deposition to obtain an initial seed layer. A predetermined proportion of doping elements is introduced into the initial seed layer, wherein the predetermined proportion can be 0.7%, and the doping element can be boron.

[0094] In one embodiment, the doping element includes at least one selected from boron, phosphorus, arsenic, antimony, gallium, and aluminum.

[0095] It should be noted that different doping elements can be selected for individual or combined doping based on different preparation requirements.

[0096] As an example, the doping element could be boron.

[0097] As another example, the doping elements can be boron and arsenic.

[0098] As another example, the doping elements can be boron, arsenic, and antimony.

[0099] As another example, the doping elements can be boron, arsenic, antimony, and gallium.

[0100] In one embodiment, the preset ratio is: , satisfy: .

[0101] It should be noted that, considering the purpose of introducing dopant elements into the initial seed layer is to improve the performance of the deposited first seed layer, a specific ratio for the trace doping of these elements needs to be set. Understandably, the preset ratios for different dopant elements can be the same or different, and all preset ratios for all dopant elements must meet the aforementioned range requirements. Specifically, for dopant elements such as boron and arsenic, a preset ratio can be set to... For gallium and aluminum, a preset ratio can be set. For arsenic and antimony, a preset ratio can be set. .

[0102] In one embodiment, the material used to prepare the surface passivation layer can be at least one of silicon nitride, aluminum oxide, silicon oxide, and silicon oxynitride.

[0103] It should be noted that, considering the different types of photovoltaic cells and their different usage requirements, different materials can be used to prepare the surface passivation layer. The surface passivation layer can be a single-layer structure prepared by a single material, or a stacked structure prepared by multiple materials.

[0104] As an example, the surface passivation layer is made of silicon nitride.

[0105] As another example, the surface passivation layer is made of silicon nitride and aluminum oxide.

[0106] As another example, the surface passivation layer is prepared from silicon nitride, aluminum oxide, and silicon oxide.

[0107] As another example, the surface passivation layer is prepared from silicon nitride, aluminum oxide, silicon oxide, and silicon oxynitride.

[0108] In one embodiment, the electrode layer is prepared from alkali metals, copper, and tin.

[0109] It should be noted that, considering the manufacturing cost of photovoltaic cells, other materials can be used to replace the materials used to prepare the electrode layer. For example, in one feasible approach, traditional back-contact cells use silver paste, which consumes a large amount and is costly. Alkali metal copper plus tin can be used to replace silver paste.

[0110] As an example, alkali metals, copper, and tin are doped in a certain mass ratio and used as materials for preparing the electrode layer.

[0111] In one embodiment, the total mass of the material used to fabricate the electrode layer is: The mass percentage of alkali metals is The mass percentage of copper is The mass percentage of tin is , , , and The following conditions must be met: , , , .

[0112] It should be noted that in the combined materials used to prepare the electrode layer, the sum of the mass percentages of all the materials is the total mass of the electrode layer. Considering the electrical performance of the photovoltaic cell, the mass percentages of different materials can be constrained according to the above-mentioned mass percentage range. Among them, tin is the main material with the highest mass percentage, alkali metals are dispersed in the tin matrix as minor components, and copper is used as a doping element.

[0113] As an example, the mass percentage of alkali metals for The mass percentage of copper is The mass percentage of tin is .

[0114] As another example, the mass percentage of alkali metals for The mass percentage of copper is The mass percentage of tin is .

[0115] As another example, the mass percentage of alkali metals for The mass percentage of copper is The mass percentage of tin is .

[0116] It is understandable that the photovoltaic cells prepared using the above embodiments can remove the original titanium-tungsten alloy layer in the complex composite seed layer material, thereby reducing the cost of titanium-tungsten alloy materials, improving ohmic contact and increasing efficiency. Furthermore, by adjusting the preparation process sequence, the removal of the titanium-tungsten alloy layer can prevent deep-level defects in the cell caused by the mutual diffusion of the first and second seed layers during annealing in the original process, and can also avoid stubborn alloys, thus facilitating the cleaning of the prepared energy-regulating cells in the later stages. In addition, if an integrated equipment is used for the preparation of photovoltaic cells, the deposition and annealing processes of the composite seed layer can be completed in one step, thereby saving turnaround time, equipment processes, and floor space. Moreover, the use of alkali metal + copper + tin preparation materials can solve the problem of excessively high costs caused by the high consumption of existing photovoltaic cells.

[0117] This embodiment also provides a photovoltaic cell, which is prepared using the photovoltaic cell preparation method described above. Figure 6 and Figure 7 As shown, where, Figure 6 To show a side view of a photovoltaic cell before etching, Figure 7 To illustrate a top view of a photovoltaic cell before etching, the photovoltaic cell includes a substrate 11, a doped semiconductor layer 12 on the back side of the substrate 11, a surface passivation layer 13 on the side of the doped semiconductor layer 12 away from the back side, the surface passivation layer 13 having a window region 14, a composite seed layer 15, wherein the composite seed layer 15 includes a first seed layer 151 and a second seed layer 152, the first seed layer being located within the window region 14, the second seed layer 152 being located on the side of the first seed layer 151 away from the doped semiconductor layer 12, and an electrode layer 16, wherein the electrode layer 16 is located on the side of the second seed layer 152 away from the first seed layer 151. Further, by etching away the portions of the first seed layer, the second seed layer, and the electroplated material layer excluding the window region, the electrode layer is obtained. Therefore, as... Figure 8 and Figure 9 As shown, Figure 8 To show the side view of the photovoltaic cell after etching, Figure 9 The top view of the photovoltaic cell after etching shows that, since the parts of the first seed layer, the second seed layer, and the electroplating material layer except for the windowed area have been etched, the windowed area 14 is partially retained on the first seed layer 151, the second seed layer 152, and the electrode layer 16. Consequently, the windowed area 14 is replaced by a solid line instead of a dashed line to clearly indicate the actual range of the retained electrode area. Accordingly, in the top view of the photovoltaic cell after etching, only the original dashed windowed area shows a solid electrode layer pattern. The seed layer and electroplating material layer in the non-windowed area have been etched away, directly exposing the surface passivation layer.

[0118] In one feasible approach, the back-contact solar cell is prepared using the following photovoltaic cell fabrication method:

[0119] 1) Provide a silicon substrate as a substrate, and perform element doping on the back side of the substrate to form a doped semiconductor layer;

[0120] 2) A surface passivation layer is deposited on the side of the doped semiconductor layer away from the substrate, wherein the material for the surface passivation layer is silicon nitride;

[0121] 3) After the surface passivation layer undergoes high-temperature annealing, the surface passivation layer is laser-cut to obtain the back contact battery precursor.

[0122] 4) An initial seed layer is deposited on the surface passivation layer. Under vacuum, a preset proportion of doping elements is introduced into the initial seed layer to obtain the first seed layer. The substrate material of the initial seed layer is an aluminum-silicon alloy, the doping element is boron, the preset proportion is 0.05%, and the first thickness of the deposited first seed layer is 30 nm.

[0123] 5) Anneal the first seed layer. After the first seed layer is annealed, staged film deposition is performed on the surface of the first seed layer until the second seed layer is obtained. The substrate material of the second seed layer is copper, and the second thickness of the second seed layer is 100 nm.

[0124] 6) Electroplating is performed on the second seed layer to obtain an electroplating material layer, wherein the material of the electroplating material layer is copper;

[0125] 7) Etching removes the portions of the first seed layer, the second seed layer, and the electroplated material layer, excluding the windowed areas, to obtain the electrode layer, thereby forming a photovoltaic cell. The electrode layer is prepared from a mixture of alkali metals, copper, and tin, and the total mass of the electrode layer preparation material is [missing information]. The mass percentage of alkali metals is The mass percentage of copper is The mass percentage of tin is , for , for , for .

[0126] This embodiment also provides a tandem solar cell, which includes a top cell, an intermediate connecting layer, and a bottom cell, with the intermediate connecting layer connecting the bottom cell and the top cell. The top cell is one of a perovskite solar cell, a cadmium telluride photovoltaic cell, a copper indium gallium selenide photovoltaic cell, or a gallium arsenide photovoltaic cell, and the bottom cell is one of the aforementioned photovoltaic cells.

[0127] This embodiment also provides a photovoltaic module, which includes a first cover plate, a first encapsulating film, a battery string, a second encapsulating film, and a second cover plate stacked together. The battery string includes a plurality of electrically connected photovoltaic cells, which are the photovoltaic cells described above, or the battery string includes the stacked cells described above.

[0128] It should be noted that the first cover plate is located on the light-facing side of the battery string, used to transmit sunlight and also to improve the waterproof and moisture-proof capabilities of the photovoltaic module, and together with the second cover plate, seals the battery string; during the lamination process of the photovoltaic module, the first and second encapsulants are used to encapsulate the battery string, preventing the external environment from affecting the performance of the battery string, and at the same time, they can also bond the first cover plate, the battery string and the second cover plate into a whole.

[0129] The first and second films can be made of one of the following materials: ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), polyvinyl butyral (PVB), etc., or they can be EPE film (EVA-POE-EVA co-extrusion structure) or EP film (EVA-EP co-extrusion structure).

[0130] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a photovoltaic cell, characterized in that, The method includes: A substrate is provided, and a functional layer is prepared on the substrate to form a battery intermediate, wherein a surface passivation layer is disposed on the battery intermediate, and the surface passivation layer is provided with a window area; A first seed layer is deposited on the surface passivation layer, and the first seed layer is annealed. A second seed layer is deposited on the annealed first seed layer; An electroplating material layer is obtained by electroplating on the second seed layer; Etching removes portions of the first seed layer, the second seed layer, and the electroplated material layer, excluding the windowed area, to obtain an electrode layer, thereby forming a photovoltaic cell.

2. The method for preparing a photovoltaic cell according to claim 1, characterized in that, The battery intermediate includes a back-contact battery precursor; the process of fabricating a functional layer on the substrate to form the battery intermediate includes: A doped semiconductor layer is formed on the back side of the substrate; The surface passivation layer is deposited on the side of the doped semiconductor layer away from the substrate; The surface passivation layer is laser-cut to obtain the back contact battery precursor.

3. The method for preparing a photovoltaic cell according to claim 1, characterized in that, The deposition of the second seed layer on the annealed first seed layer includes: A phased film deposition process is performed on the surface of the first seed layer until the second seed layer is obtained.

4. The method for preparing a photovoltaic cell according to claim 1, characterized in that, The first seed layer is made of an alloy material, the second seed layer is made of a metallic material, and the first thickness of the first seed layer is less than the second thickness of the second seed layer.

5. The method for preparing a photovoltaic cell according to claim 4, characterized in that, The first thickness is The second thickness is , and satisfy: ， 。 6. The method for preparing a photovoltaic cell according to claim 4, characterized in that, The first seed layer comprises at least one of aluminum-silicon alloy, aluminum-copper alloy, aluminum-titanium alloy, nickel-vanadium alloy, and copper-silicon alloy, and the second seed layer comprises at least one of copper, aluminum, nickel, and silver.

7. The method for preparing a photovoltaic cell according to claim 1, characterized in that, The deposition of the first seed layer on the surface passivation layer includes: An initial seed layer is deposited on the surface passivation layer; In a vacuum state, a predetermined proportion of doping elements are introduced into the initial seed layer to obtain the first seed layer.

8. The method for preparing a photovoltaic cell according to claim 7, characterized in that, The preset ratio is , satisfy: .

9. The method for preparing a photovoltaic cell according to claim 7, characterized in that, The doping element includes at least one of boron, phosphorus, arsenic, antimony, gallium, and aluminum.

10. The method for preparing a photovoltaic cell according to claim 1, characterized in that, The material used to prepare the surface passivation layer includes at least one of silicon nitride, aluminum oxide, silicon oxide, and silicon oxynitride.

11. The method for preparing a photovoltaic cell according to claim 1, characterized in that, The materials used to prepare the electrode layer include alkali metals, copper, and tin.

12. The method for preparing a photovoltaic cell according to claim 11, characterized in that, The total mass of the materials used to prepare the electrode layer is The mass percentage of the alkali metal is The mass percentage of copper is The mass percentage of tin is , , , and The following conditions must be met: , , , .

13. A photovoltaic cell, characterized in that, The photovoltaic cell is prepared using the photovoltaic cell preparation method according to any one of claims 1 to 12, comprising: Substrate; A doped semiconductor layer is located on the back side of the substrate; A surface passivation layer is located on the side of the doped semiconductor layer away from the back side, and the surface passivation layer is provided with a window area; A composite seed layer, comprising a first seed layer and a second seed layer, wherein the first seed layer is located within the windowed region and the second seed layer is located on the side of the first seed layer away from the doped semiconductor layer; The electrode layer is located on the side of the second seed layer that is away from the first seed layer.

14. A stacked battery, characterized in that, The stacked battery includes a top battery, an intermediate connecting layer, and a bottom battery, wherein the intermediate connecting layer connects the top battery and the bottom battery. The top cell is one of a perovskite cell, a cadmium telluride photovoltaic cell, a copper indium gallium selenide photovoltaic cell, or a gallium arsenide photovoltaic cell, and the bottom cell is the photovoltaic cell as described in claim 13.

15. A photovoltaic module, characterized in that, The photovoltaic module includes a first cover plate, a first encapsulating film, a battery string, a second encapsulating film, and a second cover plate stacked together. The battery string includes a plurality of electrically connected photovoltaic cells, wherein the photovoltaic cells are the photovoltaic cells as described in claim 13, or the battery string includes tandem cells as described in claim 14.

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