A stacked solar cell and a method of manufacturing the same

Abstract

The application relates to the technical field of solar cells, and discloses a laminated solar cell and a preparation method thereof. The preparation method comprises the following steps: providing a bottom cell provided with a first electrode and a second electrode with opposite electric properties; forming an intermediate layer on one side surface of the bottom cell; forming a top cell on the intermediate layer; forming a potential well structure penetrating through the top cell, the intermediate layer and the bottom cell, one end of the potential well structure close to the bottom cell being connected with the first electrode or the second electrode; forming a third electrode on the top cell, the third electrode being connected with the other end of the potential well structure away from the bottom cell, so that the potential well structure is electrically connected with the top cell and the bottom cell. By forming the penetrating potential well structure in the cell, efficient charge extraction in the top cell and the bottom cell is realized respectively, internal heat is uniformly distributed, the performance of the cell is not affected, and additional wiring is not generated, the performance and photoelectric conversion efficiency of the laminated solar cell are improved, the cell structure is miniaturized, the cost is reduced, and a light-weight product is possible.

Description

Technical Field

[0001] This invention relates to the field of tandem solar cell technology, and more specifically to a tandem solar cell and its fabrication method. Background Technology

[0002] Tandem solar cells have different absorption band gaps between their top and bottom cells, enabling them to absorb light over a wider range and resulting in higher photoelectric conversion efficiency. In a conventional two-terminal (2T) monolithic perovskite / crystalline silicon tandem solar cell structure, the top cell is a perovskite solar cell near the light-receiving surface, while the bottom cell is a crystalline silicon solar cell. The absorption layer band gap of the top perovskite solar cell is approximately 1.6 to 1.75 eV, primarily used for absorbing ultraviolet light, while the silicon material of the bottom crystalline silicon solar cell has a band gap of approximately 1.12 eV, primarily absorbing visible and infrared light. In a 2T tandem solar cell, the electrodes of the top cell and the bottom cell are directly connected to achieve current harvesting. Therefore, the total voltage is the sum of the voltages of the top and bottom cells. However, since the current paths of the top and bottom cells share the same loop, the actual current harvested is limited by the smaller current value between the two. That is, in a 2T monolithic perovskite / crystalline silicon tandem solar cell, the voltage is the sum of the voltages of the top and bottom cells, while the current is limited by the lower current value of the two cells. The current mismatch between the top and bottom cells will have a significant impact on the cell performance. Not only is the output current limited, but the fill factor (FF) will also decrease, resulting in a decrease in the overall photoelectric conversion efficiency of the tandem solar cell.

[0003] To address this issue, three-terminal (3T) monolithic perovskite / crystalline silicon tandem solar cells have received widespread attention in recent years. 3T tandem solar cells connect two sub-cells, the top and bottom cells, in series via a high-transmittance conductive thin film layer, which serves as a common electrode for both sub-cells, collecting photogenerated carriers generated by each cell. This allows for the separate collection of current flowing from the top and bottom cells, thus avoiding the main problem of 2T tandem solar cells—current mismatch. However, while the connection method between the top and bottom cells in a 3T tandem solar cell is similar to that of a 2T tandem solar cell, the bottom cell typically uses a back-contact (BC) solar cell or an intermediate layer to connect the top and bottom cells. Therefore, a 3T tandem solar cell requires an additional electrode compared to a 2T tandem solar cell. This necessitates additional wiring during module assembly, increasing module cost and complicating the manufacturing process. Summary of the Invention

[0004] In view of this, the present invention provides a tandem solar cell and its preparation method to solve the problems of complex structure, difficulty in lightweighting and mass production of existing tandem solar cells.

[0005] In a first aspect, the present invention provides a method for preparing a tandem solar cell, comprising:

[0006] A bottom battery is provided, on which a first electrode and a second electrode with opposite electrical polarities are disposed;

[0007] An intermediate layer is formed on one side surface of the bottom battery;

[0008] A top cell is formed on the surface of the middle layer opposite to the bottom cell to form the main structure of the stacked solar cell;

[0009] A potential well structure is formed in the main structure of the tandem solar cell. The potential well structure runs through the top cell, the middle layer and the bottom cell, and the end of the potential well structure near the bottom cell is connected to the first electrode or the second electrode.

[0010] A third electrode is formed on the surface of the top cell away from the bottom cell. The third electrode is connected to the end of the potential well structure away from the bottom cell, so that the potential well structure is electrically connected to the top cell and the bottom cell.

[0011] Beneficial effects: The method for fabricating tandem solar cells of the present invention forms a potential well structure that runs through the top cell, middle layer, and bottom cell within the main structure of the tandem solar cell. This enables efficient charge extraction from the top and bottom cells, while uniformly dispersing internal heat, avoiding the impact of heat accumulation on cell performance, and improving the performance stability and photoelectric conversion efficiency of the tandem solar cell. Furthermore, it avoids the need for additional external wiring, simplifies internal wiring, provides more possibilities for tandem cell design, miniaturizes the tandem solar cell structure, reduces costs, and enables lightweight products, making it particularly suitable for applications such as building-integrated photovoltaics.

[0012] In one alternative embodiment, the step of forming a potential well structure in the tandem solar cell body structure includes:

[0013] Atmospheric pressure plasma technology is used to drill holes on one side of the top cell or the bottom cell of the tandem solar cell main structure to form a potential well that runs through the top cell, the middle layer and the bottom cell.

[0014] A potential well structure is formed by filling the potential well with conductive material.

[0015] Beneficial effects: The method of forming potential wells using atmospheric pressure plasma technology can firstly create nanoscale fine patterns with excellent uniformity; secondly, because plasma is used for etching and drilling, soft etching can be performed, causing minimal damage to the structure; and thirdly, atmospheric pressure plasma etching technology can achieve a higher aspect ratio than laser methods, facilitating the etching of narrow and deep spaces, thus maximizing production line throughput. Filling the potential well with conductive material creates the potential well structure, allowing for rapid and efficient charge flow to the structure, improving charge collection efficiency and amount, and ultimately enhancing photoelectric conversion efficiency.

[0016] In one alternative implementation, atmospheric pressure plasma technology includes: dielectric barrier discharge, plasma jet, or plasma torch.

[0017] Beneficial effects: Dielectric barrier discharge (DBD) can operate at high pressure and over a wide frequency range without requiring a vacuum system. During the drilling process, the low-temperature plasma generated by DBD pre-treats the material surface, altering its physical morphology and chemical composition through its chemical activity, thus facilitating drilling. Plasma jet drilling utilizes high-temperature plasma jets with extremely high temperature and energy density. When these jets act on the material surface, they rapidly heat the material to a molten or even vaporized state. Subsequently, the molten material is removed by jetting, ultimately forming the desired hole. Plasma torch drilling applies high voltage and high-frequency current to a gas (usually an inert gas or a mixture of gases), ionizing the gas and generating high-temperature plasma. This method offers fast drilling speeds and produces smooth, burr-free holes.

[0018] In one alternative implementation, atmospheric pressure plasma technology is used to perform a perforation process on the side of the top battery opposite to the bottom battery, including:

[0019] A mask is placed on the surface of the top cell facing away from the bottom cell. The mask has a cutout area to expose part of the top cell.

[0020] The tandem solar cell main structure with a mask is placed in an atmospheric pressure plasma device for processing to form a potential well in the tandem solar cell main structure exposed by the mask.

[0021] Beneficial effects: The mask selectively blocks the main structure of the tandem solar cell, exposing the area where potential wells need to be formed. Then, atmospheric pressure plasma equipment is used to spray plasma to etch and remove the tandem solar cells exposed by the mask, forming several potential wells efficiently and quickly without damaging the cell materials.

[0022] In one alternative embodiment, the number of potential wells is 800 to 1000, and the diameter of the potential wells is 50 μm to 100 μm.

[0023] Beneficial effects: Setting up several potential wells enables full extraction of internal charge from the top and bottom cells, while setting their diameter to the micrometer level facilitates full photoelectric conversion of the cells.

[0024] In one alternative embodiment, the mask comprises an Invar alloy material and has a thickness of less than 1 μm.

[0025] Beneficial effects: The photomask is made of Invar alloy, which has a low coefficient of thermal expansion and can maintain its length over a wide temperature range, facilitating precise dimensional control. Secondly, it exhibits good stability; even under extreme temperature conditions, Invar alloy maintains stable shape and strength, and is not prone to deformation or cold cracking. The photomask's thickness is less than 1μm, facilitating patterning and processing.

[0026] In one optional embodiment, the atmospheric pressure plasma device includes: a chamber, a conveying structure, a heating structure, and a plasma source. The conveying structure is located at the bottom of the chamber and is adapted to receive the tandem solar cell main body structure and convey the tandem solar cell main body structure along a preset direction. The heating structure is disposed on the conveying structure and is adapted to heat the conveying structure. The heating structure includes a molding heater or a lamp heater (not shown in the figure). The plasma source is disposed at the top of the chamber and is adapted to spray plasma onto the tandem solar cell main body structure carried on the conveying structure.

[0027] Beneficial effects: A conveyor structure, such as a conveyor belt, is installed at the bottom of the chamber of the atmospheric pressure plasma device to continuously move and transport the main structure of the tandem solar cell. A heating structure is located below the conveyor structure to heat it. Precise temperature control can be achieved by controlling the power and operating time of the heating elements, resulting in efficient and rapid heating. A plasma source is located above the conveyor structure to spray plasma onto one side of the structure. By setting the plasma injection frequency and the conveying speed of the conveyor structure, uniform and rapid potential well formation on the tandem solar cell can be efficiently achieved.

[0028] In one alternative embodiment, processing the tandem solar cell body structure with a mask in an atmospheric pressure plasma device includes:

[0029] Turn on the heating structure to heat the conveying structure to between 50°C and 100°C;

[0030] The main structure of the tandem solar cell with a mask is placed on the delivery structure;

[0031] The plasma source ejects plasma toward the transport structure. The plasma includes one or more of the following: argon, helium, hydrogen, sulfur hexafluoride, nitrogen trifluoride, and oxygen. The frequency range of the plasma generated by the plasma source is 40kHz to 300kHz, and the power range of the plasma source is 100W to 3000W.

[0032] Beneficial effects: Before plasma jetting, the heating structure is first activated to heat the conveying structure, maintaining its temperature between 50℃ and 100℃. This improves the efficiency of plasma jetting and drilling while ensuring the structural stability and performance of the tandem solar cells. After the conveying structure is heated, the tandem solar cells to be processed are placed at the starting end of the conveying structure through the inlet of the atmospheric pressure plasma equipment. The conveying structure then moves the main structure of the tandem solar cells uniformly to the left. Simultaneously, the plasma source is activated to jet high-energy plasma downwards, rapidly forming several potential wells on the main structure of the tandem solar cells. Using a gaseous medium as the jetting plasma helps avoid damage to the cell structure and ensures the performance of the tandem solar cells.

[0033] In one alternative embodiment, the bottom cell includes a first surface and a second surface disposed opposite to each other, with an intermediate layer disposed on the first surface; the top cell includes a perovskite solar cell.

[0034] The first electrode and the second electrode are located on the first surface and the second surface of the bottom cell, respectively; or both the first electrode and the second electrode are located on the second surface.

[0035] Beneficial effects: The top cell of a tandem solar cell is a perovskite thin-film solar cell, and the bottom cell can be a heterojunction cell with the positive and negative electrodes set on opposite sides of the cell, a tunnel oxide passivated contact cell, or a back contact cell with the positive and negative electrodes set on the same side of the cell, such as an interdigitated back contact cell, which has a wide range of applications.

[0036] Secondly, the present invention also provides a tandem solar cell, fabricated using the above-described method for preparing a tandem solar cell, comprising: a bottom cell, an intermediate layer, a top cell, a first electrode, a second electrode, a third electrode, and a potential well structure. The bottom cell has a first electrode and a second electrode with opposite electrical polarities disposed on it. The intermediate layer is disposed on one side surface of the bottom cell. The top cell is disposed on the side surface of the intermediate layer facing away from the bottom cell. The bottom cell, intermediate layer, and top cell form the main structure of the tandem solar cell. The potential well structure is disposed within the main structure of the tandem solar cell, penetrating the top cell, intermediate layer, and bottom cell, with one end near the bottom cell connected to either the first electrode or the second electrode. The third electrode is disposed on the side surface of the top cell facing away from the bottom cell, and is connected to the end of the potential well structure near the top cell, so that the potential well structure electrically connects the top cell and the bottom cell.

[0037] Beneficial effects: The tandem solar cell of the present invention has a potential well structure that runs through the top cell, middle layer and bottom cell inside the main structure of the tandem solar cell. This enables efficient charge extraction from the top cell and bottom cell, while uniformly dispersing internal heat, avoiding the impact of heat accumulation on cell performance, improving the performance stability and photoelectric conversion efficiency of the tandem solar cell. In addition, it avoids the need for additional external wiring, simplifies internal wiring, provides more possibilities for cell unit stacking design, miniaturizes the tandem solar cell structure, reduces costs and makes lightweight products possible, especially suitable for applications such as building-integrated photovoltaics. Attached Figure Description

[0038] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of a two-terminal (2T) stacked solar cell in the prior art;

[0040] Figure 2 This is a schematic diagram of the structure of a three-terminal (3T) tandem solar cell in the prior art;

[0041] Figure 3 This is a schematic flowchart of the method for preparing a tandem solar cell according to an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of the bottom battery structure according to an embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of a structure in which a first electrode and a second electrode are formed on a bottom battery according to an embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram of another structure in which the first electrode and the second electrode are formed on the bottom battery according to an embodiment of the present invention;

[0045] Figure 7 This is a schematic diagram of the structure after an intermediate layer is formed on the bottom battery according to an embodiment of the present invention;

[0046] Figure 8 This is a schematic diagram of the structure after the top battery is formed on the intermediate layer according to an embodiment of the present invention;

[0047] Figure 9 This is a schematic diagram of the structure after the formation of the potential well according to an embodiment of the present invention;

[0048] Figure 10 This is a schematic diagram of the structure after filling the potential well with conductive material according to an embodiment of the present invention;

[0049] Figure 11 This is a schematic diagram of the structure after the third electrode is formed on the top battery according to an embodiment of the present invention;

[0050] Figure 12 This is a schematic diagram of a structure for connecting a stacked solar cell to an electrical appliance according to an embodiment of the present invention;

[0051] Figure 13 This is another schematic diagram of the connection between the stacked solar cell and the electrical appliance according to an embodiment of the present invention;

[0052] Figure 14 This is a schematic diagram of the internal structure of the atmospheric pressure plasma device according to an embodiment of the present invention;

[0053] Figure 15 This is a schematic diagram comparing the photoelectric conversion efficiency of a battery formed using atmospheric pressure plasma technology in an embodiment of the present invention and a battery formed using laser technology in a related scheme.

[0054] Explanation of reference numerals in the attached figures:

[0055] 1. Bottom cell; 101. First surface; 102. Second surface; 2. First electrode; 3. Second electrode; 4. Intermediate layer; 5. Top cell; 6. Potential well structure; 601. Potential well; 602. Conductive material; 7. Third electrode; 8. Mask; 9. Transport structure; 10. Plasma source; 11. Wiring; 12. Electrical appliance. Detailed Implementation

[0056] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the drawings, not all structures. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of the invention. Various structural schematic diagrams according to embodiments of the present invention are shown in the drawings. These figures are not drawn to scale, and some details are enlarged for clarity, and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from actual practices due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. Additionally, if one layer / component is "above" another layer / component in one orientation, then when the orientation is reversed, that layer / component can be "below" that other layer / component.

[0057] With the continuous development and advancement of new materials, perovskite materials have demonstrated great potential in many fields. For example, perovskite materials are used in solar cells. Furthermore, perovskite materials exhibit high performance and potential as semiconductor media in other optoelectronic devices, especially since some perovskites exhibit strong photoluminescence properties, making them promising candidates for light-emitting diodes (LEDs). Moreover, some perovskites possess coherent emission characteristics, implying their significant potential in electrically driven lasers. In these optoelectronic devices, electron and hole carriers are injected into the photoluminescent medium, whereas in solar cells, carriers need to be extracted to generate current. In the field of solar cells, perovskite materials can be used to prepare perovskite thin films using techniques such as solution processing and vacuum evaporation, and then to fabricate perovskite solar cells. Perovskite solar cells, as top cells, can be combined with different bottom cells to form tandem solar cells, such as perovskite / crystalline silicon tandem solar cells.

[0058] like Figure 1As shown, in a typical two-terminal (2T) monolithic perovskite / crystalline silicon tandem solar cell, the electrodes of the top perovskite cell are directly connected to the electrodes of the bottom crystalline silicon cell for current harvesting. The voltage is the sum of the voltages of the top cell (5) and the bottom cell (1), while the current is limited by the lower current value of the two cells. This current mismatch between the top and bottom cells significantly affects the cell performance, not only limiting the output current of the tandem solar cell but also reducing the fill factor (FF), thus leading to a decrease in the overall photoelectric conversion efficiency of the tandem cell. Figure 2 As shown, the three-terminal (3T) monolithic perovskite / crystalline silicon tandem solar cell connects the top cell 5 and the bottom cell 1 in series through a high-light-transmittance conductive thin film layer, namely the middle layer 4, which serves as a common electrode for the two sub-cells, collecting the photogenerated carriers generated by each sub-cell. It can collect the current moving from the top cell 5 and the bottom cell 1 respectively, thus avoiding the main problem of 2T tandem solar cells—current mismatch. However, although the connection method between the top cell 5 and the bottom cell 1 in the 3T tandem solar cell is similar to that of the 2T tandem solar cell, the bottom cell 1 is usually a back-contact solar cell. Therefore, the 3T tandem solar cell requires an additional electrode compared to the 2T tandem solar cell. This results in additional wiring 11 during the assembly of the solar module, increasing the cost of the module and making the process more complex.

[0059] Therefore, there is an urgent need to design a tandem solar cell that is simple in structure, low in cost, and has high photoelectric conversion efficiency. Based on this, such as... Figures 3 to 15 As shown, this embodiment provides a method for fabricating a tandem solar cell. Figure 3 The diagram below illustrates the process of this preparation method, which includes the following steps:

[0060] Step S301: Provide a bottom battery 1, on which a first electrode 2 and a second electrode 3 with opposite electrical properties are disposed.

[0061] like Figure 4 As shown, firstly, a bottom cell 1 is fabricated; then, a first electrode 2 and a second electrode 3 are fabricated on the bottom cell 1, forming a structure as shown. Figure 5 The heterojunction with intrinsic thin-layer cell (HJT cell) or tunnel oxide passivating contact cell (TOPCon cell) shown, or as... Figure 6The bottom battery 1 shown is of the type of interdigitated back contact cell (IBC battery). In this embodiment, the TOPCon battery is used as an example for the following description. One of the first electrode 2 and the second electrode 3 is a positive electrode, and the other is a negative electrode. The first electrode 2 and the second electrode 3 can be formed by screen printing or magnetron sputtering.

[0062] In step S302, an intermediate layer 4 is formed on one side surface of the bottom battery 1.

[0063] refer to Figure 7 In this embodiment, an intermediate layer 4 is formed on the surface of the bottom cell 1 near the light-receiving side. The intermediate layer 4 is heavily doped (doping concentration of 10). 19 cm -3 The above) are formed, or a transparent electrode is formed using a transparent thin-film conductive material 602.

[0064] In step S303, a top cell 5 is formed on the surface of the intermediate layer 4 facing away from the bottom cell 1 to form the main structure of the stacked solar cell.

[0065] For example, the top cell 5 is a perovskite thin-film solar cell, including a first carrier transport layer, a perovskite absorber layer and a second carrier transport layer stacked sequentially on the intermediate layer 4. In the first carrier transport layer and the second carrier transport layer, one of them is an electron transport layer (ETL) and the other is a hole transport layer (HTL). The electron transport layer includes one of titanium dioxide (TiO), tin dioxide (SnO), zinc oxide (ZnO), a C60 derivative (Phenyl-C61-Butyric Acid Methyl Ester, abbreviated as PCBM), and C60; the hole transport layer can be one of nickel oxide (NiOx), poly[bis4-phenyl)(2,4,6-trimethylphenyl)amine, 2,2',7,7'-tetratetra[n,n-bis(4-methoxyphenyl)amino]-9,9'-spirodifluorene, or poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate, abbreviated as PEDOT); the perovskite absorber layer includes methylammonium lead iodide (MAPbI) or formamidinium lead iodide. Iodide (abbreviated as FAPbI), mixed cationic perovskites, and 2D / 3D halide perovskites are all types of perovskites.

[0066] In step S304, a potential well structure 6 is formed in the main structure of the tandem solar cell. The potential well structure 6 penetrates the top cell 5, the intermediate layer 4 and the bottom cell 1, and the end of the potential well structure 6 near the bottom cell 1 is connected to the first electrode 2 or the second electrode 3.

[0067] Compared to the conventional 3T structure which uses an extended external wiring 11 for connection, this embodiment forms a through-hole potential well structure 6 inside the main structure of the tandem solar cell, such as... Figure 9 and Figure 10As shown, the potential well structure 6 enables direct connection between the top cell 5 and the bottom cell 1. Firstly, it allows for the extraction of charges generated inside the top cell 5 and the bottom cell 1, reducing contact resistance and shortening the conductive path, thus significantly reducing voltage loss and avoiding current matching issues in series-parallel structures, thereby improving photoelectric conversion efficiency. Secondly, the presence of the potential well structure 6 inside the cell eliminates the need for additional wiring 11 for external electrical discharge, improving space utilization and facilitating the fabrication of thinner and more efficient solar modules. Thirdly, by directly connecting the top cell 5 and the bottom cell 1 using the potential well structure 6, each cell can operate independently, effectively dispersing the heat generated inside the cell. Heat is not concentrated on a single cell but is evenly distributed between the top cell 5 and the bottom cell 1, helping to prevent performance degradation due to high temperatures and thus improving the long-term stability of the tandem solar cell.

[0068] In step S305, a third electrode 7 is formed on the surface of the top cell 5 away from the bottom cell 1. The third electrode 7 is connected to the end of the potential well structure 6 away from the bottom cell 1, so that the potential well structure 6 is electrically connected to the top cell 5 and the bottom cell 1.

[0069] like Figure 11 As shown, a third electrode 7 is provided on the top cell 5 to efficiently collect the charge of the top cell 5. The potential well structure 6 is connected to the third electrode 7. While the potential well structure 6 extracts the charge inside the top cell 5, it can also further extract the charge through the connected third electrode 7, thereby achieving the fastest and most maximized charge extraction, effectively improving the photoelectric conversion efficiency of the tandem solar cell, and ultimately achieving effective power supply to the electrical appliance 12, such as... Figure 12 and Figure 13 .

[0070] In summary, the fabrication method of the tandem solar cell in this embodiment achieves efficient charge extraction from the top cell 5 and the bottom cell 1 by forming a potential well structure 6 that penetrates the top cell 5, the middle layer 4, and the bottom cell 1 within the main structure of the tandem solar cell. Simultaneously, it uniformly disperses internal heat, avoiding the impact of heat accumulation on cell performance, thus improving the performance stability and photoelectric conversion efficiency of the tandem solar cell. Furthermore, it avoids the need for additional external wiring 11, simplifies internal wiring 11, provides more possibilities for tandem cell design, miniaturizes the tandem solar cell structure, reduces costs, and enables lightweight products, making it particularly suitable for applications such as building-integrated photovoltaics (BIPV).

[0071] In this embodiment, the aforementioned tandem solar cell is specifically a perovskite / crystalline silicon tandem solar cell. The top cell 5 is a perovskite thin-film solar cell. The bottom cell 1 can be a heterojunction cell (HJT cell) with the positive electrode and the negative electrode respectively set on both sides of the cell, or a tunnel oxide passivating contact cell (TOPCon cell). Alternatively, it can be a back contact cell with the positive electrode and the negative electrode set on the same side of the cell, such as an interdigitated back contact cell (IBC cell). That is, the bottom battery 1 includes a first surface 101 and a second surface 102 disposed opposite to each other. An intermediate layer 4 is disposed on the first surface 101. The first electrode 2 and the second electrode 3 can be located on the first surface 101 and the second surface 102 of the bottom battery 1 respectively, or the first electrode 2 and the second electrode 3 can both be located on the second surface 102. One of the first electrode 2 and the second electrode 3 is a positive electrode and the other is a negative electrode. In this embodiment, the second electrode 3 and the third electrode 7 have the same electrical properties. The first electrode 2 and the third electrode 7 are respectively connected to the two ends of the potential well structure 6.

[0072] In this embodiment, reference Figure 9 and Figure 10 The step S304 of forming the potential well structure 6 in the main structure of the tandem solar cell specifically includes:

[0073] In step S3041, atmospheric pressure plasma technology is used to drill holes on one side of the top cell 5 or the bottom cell 1 of the tandem solar cell main structure to form a potential well 601 that penetrates the top cell 5, the intermediate layer 4 and the bottom cell 1.

[0074] Conventional internal drilling of solar cells typically employs laser pulse drilling, a process that is short and simple. However, forming numerous potential wells 601 within a 3T tandem solar cell structure requires a large number of laser sources, increasing process complexity, equipment costs, and reducing processing efficiency. In contrast, the atmospheric pressure plasma technology used in this application for forming potential wells 601 offers several advantages over laser methods. First, it can create nanoscale patterns with excellent uniformity. Second, because plasma etching is used, soft etching can be performed, minimizing structural damage. Furthermore, atmospheric pressure plasma etching achieves a higher aspect ratio compared to laser methods, facilitating the etching of narrow and deep spaces, thus maximizing production line output.

[0075] Step S3042: Fill the potential well 601 with conductive material 602 to form a potential well structure 6.

[0076] For example, in this embodiment, a conductive material 602 is filled into the formed potential well 601 using screen printing. The conductive material 602 can be a metal such as silver, aluminum, or copper. Filling the potential well 601 with the conductive material 602 results in a potential well structure 6, which facilitates the rapid and efficient flow of charge to the potential well structure 6, improving charge collection efficiency and collection amount, and ultimately improving photoelectric conversion efficiency.

[0077] In one embodiment, the atmospheric pressure plasma technology described above specifically includes the following methods: dielectric barrier discharge, plasma jet, or plasma torch.

[0078] Specifically, Dielectric Barrier Discharge (DBD) is a non-thermal equilibrium plasma discharge technology. Its working principle is based on a gas discharge where an insulating dielectric is inserted into the discharge space. It can operate at high pressure and over a wide frequency range without requiring a vacuum system. During the drilling process, the low-temperature plasma generated by DBD pre-treats the material surface, altering its physical morphology and chemical composition through its chemical activity, thus facilitating drilling. Plasma jet drilling primarily relies on the high temperature and energy density of plasma. During drilling, a high-temperature plasma jet is generated using a specific device (such as an atmospheric pressure plasma jet device). These jets possess extremely high temperature and energy density, rapidly heating the material surface to a molten or even vaporized state when they act on it. Subsequently, the molten material is removed by jetting, ultimately forming the desired hole in the material. Plasma torch drilling is a technique for generating directional plasma jets. It involves applying high voltage and high-frequency current to a gas (usually an inert gas or a mixture of gases) to ionize the gas and generate high-temperature plasma. These plasma jets are characterized by high temperature, high speed, and high energy. In other words, plasma torch drilling utilizes the high-temperature plasma jet to rapidly heat and melt the material surface, thus achieving the drilling purpose. During the drilling process, the jet generated by the plasma torch directly acts on the material surface, causing the material to melt rapidly and form a hole. Due to the high temperature and high energy of the plasma jet, the drilling speed is usually very fast, and the edges of the holes are smooth and burr-free.

[0079] Furthermore, step S3041, which employs atmospheric pressure plasma technology to perform perforation on the side of the top battery 5 opposite to the bottom battery 1, includes:

[0080] Step S3041a: A mask 8 is provided on the surface of the top battery 5 facing away from the bottom battery 1. The mask 8 has a cutout area to expose part of the top battery 5.

[0081] Specifically, the aforementioned mask 8 can be made of Invar alloy, also known as Invar steel, a unique nickel-iron alloy. Firstly, it has a low coefficient of thermal expansion, maintaining its length over a wide temperature range, facilitating precise dimensional control. Secondly, it exhibits good stability; even under extreme temperature conditions, Invar alloy maintains stable shape and strength, resisting deformation or cold cracking. The mask 8 has a thickness of less than 1 μm, facilitating patterning and processing.

[0082] In step S3041b, the tandem solar cell main structure with the mask plate 8 is placed in an atmospheric pressure plasma device for processing to form a potential well 601 in the tandem solar cell main structure exposed by the mask plate 8.

[0083] The mask 8 selectively blocks the main structure of the tandem solar cell, exposing the area where potential wells 601 need to be formed. Then, plasma is ejected through an atmospheric pressure plasma device to etch and remove the tandem solar cell exposed by the mask, thus efficiently and quickly forming several potential wells 601 without damaging the cell material.

[0084] In one embodiment, the number of potential wells 601 is 800 to 1000, and the diameter of the potential wells 601 is 50 μm to 100 μm. Setting up a number of potential wells 601 enables sufficient extraction of the internal charge of the top cell 5 and the bottom cell 1, while setting their diameter to the micrometer level facilitates sufficient photoelectric conversion of the cells.

[0085] In one embodiment, the atmospheric pressure plasma device specifically includes: a chamber, a conveying structure 9, a heating structure, and a plasma source 10. The conveying structure 9 is located at the bottom of the chamber and is adapted to receive the main structure of the tandem solar cell and convey the main structure of the tandem solar cell along a preset direction. The heating structure is disposed on the conveying structure 9 and is adapted to heat the conveying structure 9. The heating structure includes a molding heater or a lamp heater (not shown in the figure). The plasma source 10 is disposed at the top of the chamber and is adapted to spray plasma onto the main structure of the tandem solar cell carried on the conveying structure 9.

[0086] refer to Figure 14 A conveyor structure 9 is installed at the bottom of the chamber of the atmospheric pressure plasma device. The conveyor structure 9 can be a conveyor belt or similar structure, along which... Figure 14The tandem solar cell main structure is continuously moved and transported in a counter-clockwise direction, as shown. A heating structure is located below the transport structure 9. This heating structure can be a molding heater or a lamp heater. A molding heater is a device that converts electrical energy into heat energy through heating elements (such as heating rods or heating coils) to heat a mold. For example, a heating rod or heating coil can be placed on the back of the transport structure 9 to heat it. Its working principle is based on electrothermal conversion, and precise temperature control can be achieved by accurately controlling the power and working time of the heating elements. A lamp heater is a device that generates heat by energizing a heating element (such as a tungsten filament) inside a bulb, which then transfers the heat to the surrounding environment. Its conversion efficiency is low in the visible light range, but its efficiency in converting to total electromagnetic waves, including infrared light, is very high, resulting in efficient and rapid heating. A plasma source 10 is located above the transport structure 9 to spray plasma onto one side of the transport structure 9. By setting the plasma spray frequency and the transport rate of the transport structure 9, uniform and rapid formation of the potential well 601 on the tandem solar cell is achieved efficiently.

[0087] In one embodiment, step S3042b, which involves placing the tandem solar cell body structure having the mask 8 in an atmospheric pressure plasma device for processing, includes:

[0088] Turn on the heating structure to heat the conveying structure 9 to between 50°C and 100°C.

[0089] Before plasma jetting, the heating structure is first turned on to heat the conveying structure 9, keeping the temperature of the conveying structure 9 between 50℃ and 100℃, so as to improve the efficiency of plasma jetting and drilling, while ensuring the structural stability and performance of the tandem solar cell.

[0090] The tandem solar cell main structure with mask 8 is placed on the delivery structure 9.

[0091] After the conveying structure 9 has been heated, the main structure of the tandem solar cell to be processed is placed from the inlet of the atmospheric pressure plasma equipment to the starting end of the conveying structure 9, that is... Figure 14 The right end of the conveying structure 9 is shown, and then the conveying structure 9 drives the main structure of the stacked solar cell to move uniformly to the left.

[0092] The plasma source 10 ejects plasma toward the transport structure 9. The plasma includes one or more of argon, helium, hydrogen, sulfur hexafluoride, nitrogen trifluoride, and oxygen. The plasma source 10 generates plasma in the frequency range of 40kHz to 300kHz and in the power range of 100W to 3000W.

[0093] While the transport structure 9 moves the main structure of the tandem solar cell uniformly to the left, the plasma source 10 is activated to spray high-energy plasma downwards, thereby rapidly forming several potential wells 601 on the main structure of the tandem solar cell. Using the aforementioned gaseous medium as the sprayed plasma helps to avoid damage to the cell structure and ensure the performance of the tandem solar cell.

[0094] Figure 15 A schematic diagram illustrating the photoelectric conversion efficiency using the atmospheric pressure plasma technology provided in this embodiment and the conventional laser drilling technology is shown. Figure 15 As shown, the atmospheric pressure plasma technology provided in this embodiment has a photoelectric conversion efficiency that is basically the same as, or even better than, that of general laser drilling technology. In other words, in a 3T integrated perovskite / crystalline silicon tandem solar cell, using the atmospheric pressure plasma technology provided in this embodiment to form the potential well 601 can effectively guarantee the photoelectric conversion efficiency while improving processing efficiency and cell stability.

[0095] refer to Figure 12 and Figure 13 This embodiment also provides a tandem solar cell, fabricated using the above-described method for preparing a tandem solar cell, comprising: a bottom cell 1, an intermediate layer 4, a top cell 5, a first electrode 2, a second electrode 3, a third electrode 7, and a potential well structure 6. The bottom cell 1 is provided with a first electrode 2 and a second electrode 3 of opposite electrical polarity. The intermediate layer 4 is disposed on one side surface of the bottom cell 1. The top cell 5 is disposed on the side surface of the intermediate layer 4 facing away from the bottom cell 1. The bottom cell 1, the intermediate layer 4, and the top cell 5 form the main structure of the tandem solar cell. The potential well structure 6 is disposed in the main structure of the tandem solar cell, penetrating the top cell 5, the intermediate layer 4, and the bottom cell 1, and its end near the bottom cell 1 is connected to the first electrode 2 or the second electrode 3. The third electrode 7 is disposed on the side surface of the top cell 5 facing away from the bottom cell 1, and the third electrode 7 is connected to the end of the potential well structure 6 near the top cell 5, so that the potential well structure 6 electrically connects the top cell 5 and the bottom cell 1.

[0096] In this embodiment, a potential well structure 6 is provided inside the main structure of the tandem solar cell, penetrating the top cell 5, the middle layer 4, and the bottom cell 1. This structure enables efficient charge extraction from the top cell 5 and the bottom cell 1, while uniformly dispersing internal heat. This avoids the impact of heat accumulation on cell performance, improves the performance stability and photoelectric conversion efficiency of the tandem solar cell, and eliminates the need for additional external wiring 11. It also simplifies the internal wiring 11, provides more possibilities for cell unit stacking design, miniaturizes the tandem solar cell structure, reduces costs, and makes lightweight products possible, especially suitable for applications such as building-integrated photovoltaics.

[0097] Further functional descriptions of the above parts are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0098] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0099] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for fabricating a tandem solar cell, characterized in that, include: A bottom battery is provided, wherein a first electrode and a second electrode with opposite electrical polarities are disposed on the bottom battery; An intermediate layer is formed on one side surface of the bottom battery; A top cell is formed on the surface of the intermediate layer opposite to the bottom cell to form a stacked solar cell main structure; A potential well structure is formed in the main structure of the stacked solar cell. The potential well structure penetrates the top cell, the intermediate layer and the bottom cell, and the end of the potential well structure near the bottom cell is connected to the first electrode or the second electrode. A third electrode is formed on the surface of the top cell facing away from the bottom cell. The third electrode is connected to the end of the potential well structure away from the bottom cell, so that the potential well structure is electrically connected to the top cell and the bottom cell.

2. The method for preparing a tandem solar cell according to claim 1, characterized in that, The step of forming a potential well structure in the main structure of the stacked solar cell includes: Atmospheric pressure plasma technology is used to drill holes on one side of the top cell or the bottom cell of the tandem solar cell main structure to form a potential well that penetrates the top cell, the intermediate layer and the bottom cell; The potential well is filled with a conductive material to form the potential well structure.

3. The method for preparing a tandem solar cell according to claim 2, characterized in that, The atmospheric pressure plasma technology includes: dielectric barrier discharge, plasma jet, or plasma torch.

4. The method for preparing a tandem solar cell according to claim 3, characterized in that, The method of using atmospheric pressure plasma technology to perform drilling on the side of the top battery away from the bottom battery includes: A mask is provided on the surface of the top battery facing away from the bottom battery. The mask has a cutout area to expose a portion of the top battery. The tandem solar cell main structure with the mask is placed in an atmospheric pressure plasma device for processing to form a potential well in the tandem solar cell main structure exposed by the mask.

5. The method for preparing a tandem solar cell according to claim 4, characterized in that, The number of potential wells is 800 to 1000, and the diameter of the potential wells is 50 μm to 100 μm.

6. The method for preparing a tandem solar cell according to claim 4, characterized in that, The mask is made of Invar alloy material and has a thickness of less than 1 μm.

7. The method for preparing a tandem solar cell according to claim 4, characterized in that, The atmospheric pressure plasma device includes: chamber; A conveying structure is located at the bottom of the chamber. The conveying structure is adapted to receive the stacked solar cell main structure and convey the stacked solar cell main structure along a preset direction. A heating structure is disposed on the conveying structure and is adapted to heat the conveying structure; the heating structure includes a molding heater or a lamp heater; A plasma source, disposed at the top of the chamber, is adapted to inject plasma into the tandem solar cell main structure carried on the delivery structure.

8. The method for preparing a tandem solar cell according to claim 7, characterized in that, The process of placing the tandem solar cell main structure having the mask in an atmospheric pressure plasma device includes: The heating structure is activated to heat the conveying structure to between 50°C and 100°C. The stacked solar cell main structure having the mask is placed on the conveying structure; The plasma source ejects plasma toward one side of the conveying structure. The plasma includes one or more of argon, helium, hydrogen, sulfur hexafluoride, nitrogen trifluoride, and oxygen. The frequency range of the plasma generated by the plasma source is 40kHz to 300kHz, and the power range of the plasma source is 100W to 3000W.

9. The method for preparing a tandem solar cell according to any one of claims 1-8, characterized in that, The bottom cell includes a first surface and a second surface disposed opposite to each other, and the intermediate layer is disposed on the first surface; the top cell includes a perovskite solar cell. The first electrode and the second electrode are located on the first surface and the second surface of the bottom battery, respectively; or both the first electrode and the second electrode are located on the second surface.

10. A tandem solar cell, prepared by the method for preparing a tandem solar cell according to any one of claims 1-9, characterized in that, include: A bottom battery, wherein a first electrode and a second electrode with opposite electrical polarities are disposed on the bottom battery; An intermediate layer is disposed on one side surface of the bottom battery; The top battery is disposed on the surface of the intermediate layer opposite to the bottom battery. The bottom cell, the middle layer, and the top cell form the main structure of a stacked solar cell; A potential well structure is disposed in the main structure of the stacked solar cell. The potential well structure penetrates the top cell, the intermediate layer and the bottom cell, and one end near the bottom cell is connected to the first electrode or the second electrode. A third electrode is disposed on the surface of the top cell facing away from the bottom cell. The third electrode is connected to the end of the potential well structure near the top cell, so that the potential well structure electrically connects the top cell and the bottom cell.

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