Laminated battery and preparation method of laminated battery

Abstract

The invention provides a laminated cell and a preparation method thereof, and the laminated cell comprises a bottom cell which at least comprises a substrate and a back reflector structure located at one side of the substrate, the back reflector structure comprises a first transparent conductive layer, a barrier layer, a first anti-reflection layer and a first metal layer, the barrier layer is located at one side, far away from the substrate, of the first transparent conductive layer, and the first anti-reflection layer is located at the other side of the first transparent conductive layer; the first anti-reflection layer is located on the side, away from the first transparent conductive layer, of the barrier layer, and the first metal layer is located on the side, away from the substrate, of the first anti-reflection layer and / or the side, away from the substrate, of the first transparent conductive layer and makes contact with the first transparent conductive layer. The middle layer is located on the side, away from the back reflector structure, of the substrate; and the perovskite top cell is positioned on one side, far away from the bottom cell, of the middle layer. The stability of the laminated cell can be improved.

Description

Technical Field

[0001] This application relates to the photovoltaic field, and more specifically, to a tandem solar cell and a method for preparing the tandem solar cell. Background Technology

[0002] Tandem solar cells combine sub-cells with different bandgap widths through optical and electrical coupling to achieve segmented spectral absorption, representing a technological approach to overcome the efficiency limits of single-junction solar cells. However, due to the complexity of their structure, their stability is not ideal.

[0003] The information disclosed above in the background section is only intended to enhance the understanding of the background art of the art described herein. Therefore, the background art may contain certain information that does not constitute prior art known to those skilled in the art in this country. Summary of the Invention

[0004] The main objective of this application is to provide a tandem battery and a method for preparing a tandem battery, so as to solve the problem of how to improve the stability of tandem batteries in the prior art.

[0005] To achieve the above objectives, according to one aspect of this application, a stacked solar cell is provided, comprising: a bottom cell, including at least a substrate and a back reflector structure located on one side of the substrate, the back reflector structure including a first transparent conductive layer, a barrier layer, a first antireflective layer, and a first metal layer, wherein the barrier layer is located on the side of the first transparent conductive layer away from the substrate, the first antireflective layer is located on the side of the barrier layer away from the first transparent conductive layer, the first metal layer is located on the side of the first antireflective layer away from the substrate and / or the side of the first transparent conductive layer away from the substrate, and is in contact with the first transparent conductive layer; an intermediate layer located on the side of the substrate away from the back reflector structure; and a perovskite top cell located on the side of the intermediate layer away from the bottom cell.

[0006] Optionally, the blocking layer includes a plurality of blocking portions arranged at intervals, and the first antireflection layer includes a plurality of antireflection portions arranged at intervals.

[0007] Optionally, the width of the blocking portion is the same as the width of the anti-reflection portion along a direction perpendicular to the base.

[0008] Optionally, the blocking portion satisfies at least one of the following: the width of the blocking portion is 0.5mm to 1.5mm in the direction perpendicular to the substrate; the distance between any two adjacent blocking portions is 10μm to 100μm in the direction perpendicular to the substrate.

[0009] Optionally, in a predetermined direction, the orthographic projection of the blocking portion onto the first transparent conductive layer has a first boundary, the first transparent conductive layer has a second boundary, and the minimum distance between the first boundary and the second boundary is 1mm to 2mm, wherein the predetermined direction is perpendicular to the arrangement direction of the blocking portion.

[0010] Optionally, the material of the barrier layer includes one or more of silicon oxide, aluminum oxide, and rare earth metal oxides.

[0011] Optionally, the bottom cell satisfies at least one of the following: the thickness of the first antireflection layer is 150~300nm; the thickness of the barrier layer is 1nm~30nm.

[0012] Optionally, the bottom battery further includes a second transparent conductive layer located between the substrate and the intermediate layer.

[0013] Optionally, in the direction from the bottom cell to the perovskite top cell, the perovskite top cell includes a perovskite substrate, a connecting layer, a transport layer, a buffer layer, a third transparent conductive layer, a second antireflection layer, and a second metal layer stacked sequentially.

[0014] To achieve the above objectives, according to another aspect of this application, a method for fabricating the aforementioned stacked solar cell is provided, comprising: providing a substrate and forming a first transparent conductive layer on one side of the substrate; forming a barrier layer on a portion of the surface of the first transparent conductive layer away from the substrate; forming a first antireflective layer on the side of the barrier layer away from the first transparent conductive layer; forming a first metal layer on the side of the first transparent conductive layer away from the substrate and / or on the side of the first antireflective layer away from the barrier layer, wherein the first transparent conductive layer, the barrier layer, the first antireflective layer, and the first metal layer form a back reflector structure; and sequentially forming an intermediate layer and a perovskite top solar cell on the side of the substrate away from the back reflector structure.

[0015] This application provides a tandem solar cell, comprising a bottom cell, an intermediate layer, and a perovskite top cell. The bottom cell includes at least a substrate and a back reflector structure located on one side of the substrate. The back reflector structure includes a first transparent conductive layer, a barrier layer, a first antireflective layer, and a first metal layer. The barrier layer is located on the side of the first transparent conductive layer away from the substrate, the first antireflective layer is located on the side of the barrier layer away from the first transparent conductive layer, and the first metal layer is located on the side of the first antireflective layer away from the substrate and / or the side of the first transparent conductive layer away from the substrate, and is in contact with the first transparent conductive layer. The intermediate layer is located on the side of the substrate away from the back reflector structure, and the perovskite top cell is located on the side of the intermediate layer away from the bottom cell. This solution improves the stability of the tandem solar cell by setting a barrier layer between the first transparent conductive layer and the first antireflective layer in the back reflector structure of the bottom cell. This barrier layer prevents ions in the first antireflective layer from passing through the first transparent conductive layer into the substrate, thereby preventing damage to the bottom cell structure. This improves the stability of the tandem solar cell and solves the technical problem of how to improve the stability of tandem solar cells. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0017] Figure 1 A schematic diagram of a stacked battery structure according to an embodiment of this application is shown;

[0018] Figure 2 A schematic diagram of a back reflector structure according to an embodiment of this application is shown;

[0019] Figure 3 A top view of a back reflector structure provided according to an embodiment of this application is shown.

[0020] Figure 4 A schematic flowchart of a method for fabricating a stacked battery according to an embodiment of this application is shown.

[0021] Figure 5 A schematic diagram showing test results according to embodiments and comparative examples of this application is illustrated.

[0022] The above figures include the following reference numerals:

[0023] 10. Bottom cell; 11. Substrate; 12. Back reflector structure; 121. First transparent conductive layer; 122. Barrier layer; 123. First antireflection layer; 124. First metal layer; 125. Barrier portion; 126. Antireflection portion; 13. Second transparent conductive layer; 20. Intermediate layer; 30. Perovskite top cell; 31. Perovskite substrate; 32. Connecting layer; 33. Transport layer; 34. Buffer layer; 35. Third transparent conductive layer; 36. Second antireflection layer; 37. Second metal layer. Detailed Implementation

[0024] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0028] As described in the background section, the stability of existing stacked batteries is not ideal. To solve the above problems, embodiments of this application provide a stacked battery and a method for preparing a stacked battery.

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0030] Figure 1 This is a schematic diagram of the structure of a stacked battery according to an embodiment of this application. Figure 1 As shown, it includes:

[0031] The bottom battery 10 includes at least a substrate 11 and a back reflector structure 12 located on one side of the substrate 11. The back reflector structure 12 includes a first transparent conductive layer 121, a barrier layer 122, a first antireflective layer 123, and a first metal layer 124. The barrier layer 122 is located on the side of the first transparent conductive layer 121 away from the substrate 11. The first antireflective layer 123 is located on the side of the barrier layer 122 away from the first transparent conductive layer 121. The first metal layer 124 is located on the side of the first antireflective layer 123 away from the substrate 11 and / or on the side of the first transparent conductive layer 121 away from the substrate 11, and is in contact with the first transparent conductive layer 121.

[0032] The bottom cell 10, located in the lower layer of the stacked structure, uses a narrow bandgap material to receive long-wavelength light (650~1100nm) that the top cell fails to absorb, enabling secondary utilization of the spectrum. It converts low-energy photons into electrical energy, breaking the photocurrent limit of a single-junction cell. The back reflector structure 12 is an optical functional layer located on one side of the bottom of the bottom cell 10. Its main function is to reflect long-wavelength photons that penetrate the absorption layer back into the cell, achieving secondary or multiple absorption, thereby improving photoelectric conversion efficiency and reducing material usage. In practical applications, in silicon-based thin-film stacked cells (such as amorphous silicon / microcrystalline silicon stacks), long-wavelength photons (650~1200nm) are difficult to completely capture by the thin absorption layer. The back reflector reflects these photons through optical interference or photon bandgap effects, which can more than double the optical path length. Furthermore, the short-circuit current of a stacked cell is limited by the cell with the smallest current. The back reflector structure 12 can selectively enhance the long-wavelength absorption of the bottom cell 10, helping to achieve current matching between the top and bottom cells 10 and improving the overall output. By reusing light energy, the thickness of the microcrystalline silicon bottom cell 10 can be reduced while maintaining the absorption rate, thereby lowering material costs and mitigating light-induced degradation. The first transparent conductive layer 121 can be made of a transparent conductive oxide material, such as indium-based oxides like indium tin oxide, indium zinc oxide, and indium zirconium oxide; tin-based oxides like fluorine-doped tin oxide; and zinc-based oxides like zinc aluminum oxide. The barrier layer 122 can be made of silicon oxide, aluminum oxide, rare earth metal oxides, or other substances that can block ions in the first antireflection layer 123. The first antireflection layer 123 can be made of at least one of magnesium fluoride, lithium fluoride, and sodium fluoride. The first metal layer 124 can be made of at least one of gold, silver, copper, and aluminum.

[0033] The intermediate layer 20 is located on the side of the substrate 11 away from the back reflector structure 12;

[0034] In practical applications, the intermediate layer 20 connects the top cell and the bottom cell 10. This intermediate layer 20 can also serve as a charge transport layer (CTL), functioning to perform electrical coupling and carrier recombination, optical management, and interface passivation. In the tandem cell, electrons (or holes) from the top cell recombine with holes (or electrons) from the bottom cell 10 at the interface of the intermediate layer 20, forming an electrical series connection. In practical applications, the intermediate layer 20 exhibits high tunneling current density and low resistance, ensuring that the recombination process does not become a limiting factor. Furthermore, the intermediate layer 20 can achieve nanoscale thickness uniformity by replicating the morphology of the substrate 11, suppressing lateral leakage and preventing short circuits between the top and bottom cells 10.

[0035] The perovskite top cell 30 is located on the side of the intermediate layer 20 away from the bottom cell 10.

[0036] The perovskite top cell 30 is a sub-cell located near the incident light side in the tandem solar cell. It is used to absorb high-energy, short-wavelength light (such as ultraviolet light, 300~700nm) to avoid thermal loss of high-energy photons. Furthermore, the short-circuit current of the perovskite top cell 30 is matched with that of the bottom cell 10.

[0037] An embodiment of this application provides a stacked solar cell, including a bottom cell, an intermediate layer, and a perovskite top cell. The bottom cell includes at least a substrate and a back reflector structure located on one side of the substrate. The back reflector structure includes a first transparent conductive layer, a barrier layer, a first antireflective layer, and a first metal layer. The barrier layer is located on the side of the first transparent conductive layer away from the substrate, the first antireflective layer is located on the side of the barrier layer away from the first transparent conductive layer, and the first metal layer is located on the side of the first antireflective layer away from the substrate and / or the side of the first transparent conductive layer away from the substrate, and is in contact with the first transparent conductive layer. The intermediate layer is located on the side of the substrate away from the back reflector structure, and the perovskite top cell is located on the side of the intermediate layer away from the bottom cell. This solution improves the stability of the stacked solar cell by setting a barrier layer between the first transparent conductive layer and the first antireflective layer in the back reflector structure of the bottom cell. This barrier layer is used to prevent ions in the first antireflective layer from passing through the first transparent conductive layer into the substrate, thereby preventing damage to the bottom cell structure. This improves the stability of the stacked solar cell and solves the technical problem of how to improve the stability of the stacked solar cell.

[0038] In the specific implementation process, such as Figure 2As shown, the barrier layer 122 includes a plurality of spaced-apart barrier portions 125, and the first antireflective layer 123 includes a plurality of spaced-apart antireflective portions 126. The first antireflective layer 123 is located on the side of the barrier layer 122 away from the first transparent conductive layer 121, and the first metal layer 124 is located on the side of the first antireflective layer 123 away from the first transparent conductive layer 121 and / or on the side of the first transparent conductive layer 121 away from the substrate, and is in contact with the first transparent conductive layer 121. By using the spaced-apart first antireflective layer 123 and the spaced-apart barrier layer 122, excellent optical performance can be maintained while also considering electrical performance, process stability, and cost-effectiveness.

[0039] In the above implementation process, the plurality of blocking portions 125 may be uniformly distributed or non-uniformly distributed. The plurality of anti-reflection portions 126 may be uniformly distributed or non-uniformly distributed. In other embodiments, the blocking portions 125 and the anti-reflection portions 126 are arranged in a one-to-one correspondence.

[0040] To further reduce the difficulty of the process, such as Figure 2 As shown, along the direction perpendicular to the base, the width of the blocking portion 125 is the same as the width of the anti-reflection portion 126.

[0041] In the above implementation scheme, the blocking part 125 and the anti-reflection part 126 have the same size, and the two layers, the blocking layer 122 and the first anti-reflection layer 123, can be directly prepared during the preparation process.

[0042] like Figure 2 As shown, the aforementioned blocking portion 125 satisfies at least one of the following: the width of the blocking portion 125 along the direction perpendicular to the substrate is 0.5 mm to 1.5 mm; and the distance between any two adjacent blocking portions 125 along the direction perpendicular to the substrate is 10 μm to 100 μm. The blocking portions 125 being within the aforementioned width range provides good blocking effect for ions in the first antireflection layer 123 while preventing an increase in lateral resistance due to excessive width, thus avoiding a reduction in the fill factor. The spacing between adjacent blocking portions 125 being within the aforementioned distance range enhances the antireflection effect of the first antireflection layer 123 and avoids increased fabrication difficulty due to excessively small spacing.

[0043] In other words, the anti-reflection portion 126 also satisfies at least one of the following: the width of the anti-reflection portion 126 in the direction perpendicular to the substrate is 0.5 mm to 1.5 mm; and the distance between any two adjacent anti-reflection portions 126 in the direction perpendicular to the substrate is 10 μm to 100 μm. In the above implementation, the width of the blocking portion 125 in the direction perpendicular to the substrate can be any value among 0.5 mm, 1.0 mm, and 1.5 mm, or it can be within the range of any two of the above values. The distance between any two adjacent blocking portions 125 in the direction perpendicular to the substrate can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, and 100 μm, or it can be within the range of any two of the above values.

[0044] In some embodiments, such as Figure 3 As shown, in the predetermined direction d, the orthogonal projection of the blocking portion 125 onto the first transparent conductive layer 121 has a first boundary, and the first transparent conductive layer 121 has a second boundary. The minimum distance between the first boundary and the second boundary is 1mm to 2mm, wherein the predetermined direction d is perpendicular to the arrangement direction of the blocking portion 125. The minimum distance between the first boundary and the second boundary is within the above range, which can prevent edge leakage and short circuits, and also prevent local stress concentration and film cracking caused by uneven thickness or edge stacking of materials (especially liquid slurry or vapor deposition) at the edges.

[0045] It should be noted that the above Figure 3 for Figure 2 In the top view, the predetermined direction d refers to the extension direction of the blocking part 125. The minimum distance between the first boundary and the second boundary can be 1 mm, 2 mm, or any two of the above values. The anti-reflection part 126 also satisfies the following: in the predetermined direction d, the orthographic projection of the anti-reflection part 126 onto the first transparent conductive layer 121 has a third boundary, and the minimum distance between the third boundary and the second boundary is 1 mm to 2 mm, wherein the predetermined direction d is perpendicular to the arrangement direction of the anti-reflection part 126.

[0046] In some embodiments, the material of the barrier layer includes one or more of silicon oxide, aluminum oxide, and rare earth metal oxides.

[0047] Because silicon oxide can form an amorphous glass network structure, which is dense and has few defects, it can directly and physically block the diffusion channels of ions in the first antireflection layer. Furthermore, its surface is rich in Si-OH groups, which chemically adsorb onto ions in the first antireflection layer in a humid and hot environment, forming stable chemical bonds and fixing free ions on the surface. In acidic or weakly alkaline environments, alumina carries a positive charge on its surface, which can electrostatically attract and capture negatively charged ions, hindering their migration. In addition, aluminum ions in alumina can form Al-O-Al bridging bonds with the matrix oxide, eliminating oxygen ion vacancies and further reducing the diffusion path of ions in the first antireflection layer via vacancies. Similarly, rare earth elements (such as Y, La, Ce) in rare earth metal oxides accumulate at grain boundaries to form oxide particles, physically blocking grain boundary diffusion. Ions in the first antireflection layer mainly migrate rapidly along grain boundaries under humid and hot conditions; this "pinning effect" can greatly reduce the ion transport cross-sectional area. Furthermore, high-valence rare earth ions can generate a strong electric field, binding anions and forming an electrostatic barrier.

[0048] like Figure 1 As shown, the bottom cell 10 satisfies at least one of the following: the thickness of the first antireflection layer 123 is 150~300 nm; the thickness of the barrier layer 122 is 1 nm~30 nm. The thickness of the first antireflection layer 123 is within the aforementioned range, ensuring good antireflection performance while preventing a significant increase in parasitic absorption due to excessive thickness. The thickness of the barrier layer 122 is also within the aforementioned range, ensuring good blocking effect for ions in the first antireflection layer 123 while preventing the barrier layer 122 from negatively impacting the photoelectric conversion efficiency of the tandem cell due to excessive thickness.

[0049] In specific implementation, the thickness of the first antireflection layer 123 can be any one of 150nm, 200nm, 250nm, and 300nm, or it can be within the range of any two of the above values. The thickness of the barrier layer 122 can be any one of 1nm, 5nm, 10nm, 15nm, 20nm, 25nm, and 30nm, or it can be within the range of any two of the above values.

[0050] In some embodiments, such as Figure 1 As shown, the bottom cell 10 further includes a second transparent conductive layer 13, located between the substrate 11 and the intermediate layer 20. The second transparent conductive layer 13, combined with the intermediate layer 20, can further enhance the optical coupling and electrical series connection between the bottom cell 10 and the perovskite top cell 30.

[0051] In practical applications, the material of the second transparent conductive layer 13 can be a transparent conductive oxide material, such as indium-based oxides like indium tin oxide, indium zinc oxide, and indium zirconium oxide; tin-based oxides like fluorine-doped tin oxide; and zinc-based oxides like zinc aluminum oxide. The material of the second transparent conductive layer 13 can be the same as or different from the material of the first transparent conductive layer 121.

[0052] In other embodiments, such as Figure 1 As shown, in the direction from the bottom cell 10 to the perovskite top cell 30, the perovskite top cell 30 includes a perovskite substrate 31, a connecting layer 32, a transport layer 33, a buffer layer 34, a third transparent conductive layer 35, a second antireflection layer 36, and a second metal layer 37 stacked sequentially. The second metal layer 37 is located on both sides of the third transparent conductive layer 35 and on both sides of the second antireflection layer 36. The film layer configuration of the perovskite top cell 30 can further improve the short-circuit current density and open-circuit voltage of the stacked cell.

[0053] The thickness of the perovskite substrate 31 ranges from 500 to 800 nm. The aforementioned connecting layer 32 can serve as an interface modification layer, preventing the top electrode metal atoms from penetrating into the perovskite substrate 31. Its materials can be various organic or inorganic functional molecules, such as carborane derivatives, silane dipole molecules, isothiocyanates and their derivatives, 4-aminotetrahydropyran bromide, etc. The aforementioned transport layer 33 can preferentially extract electrons or holes, block opposite charge types, and reduce charge recombination. Its materials can be self-assembled monolayer films (such as MeO-2PACz), organic semiconductor materials such as PTAA and PEDOT:PSS, inorganic oxides such as titanium dioxide, tin dioxide, nickel oxide, and molybdenum trioxide, carbon-based materials such as carbon nanotubes, graphene, and graphite carbon electrodes, and inorganic salt materials such as cuprous iodide, cuprous thiocyanate, and cuprous iodide-thiourea complexes. The buffer layer 34 is used to prevent the electron transport layer 33 from directly contacting the top electrode, avoiding leakage and increasing the switching voltage; its material can be BCP (bath copper spirit), and its thickness can be 8~10nm. The third transparent conductive layer 35 can be made of a transparent conductive oxide material, such as indium tin oxide, indium zinc oxide, indium zirconium oxide, etc. (indium-based oxides); tin-based oxides such as fluorine-doped tin oxide; zinc-based oxides such as zinc aluminum oxide. The material of the third transparent conductive layer 35 can be the same as or different from the materials of the second transparent conductive layer 13 and the first transparent conductive layer 121. The second antireflection layer 36 is used to reduce surface reflection, increase light incident, and increase short-circuit current density; its material can be at least one of magnesium fluoride, lithium fluoride, and sodium fluoride. The material of the second metal layer 37 can be at least one of gold, silver, copper, aluminum, etc.

[0054] This application also provides a method for preparing a stacked battery, which can be used to prepare any of the above-mentioned stacked batteries. Figure 4 This is a schematic flowchart illustrating a method for fabricating a tandem battery according to an embodiment of this application. Figure 4 As shown, the above method includes:

[0055] Step S501: Provide a substrate and form a first transparent conductive layer on one side of the substrate;

[0056] Specifically, the material of the first transparent conductive layer can be a transparent conductive oxide material, such as indium-based oxides such as indium tin oxide, indium zinc oxide, and indium zirconium oxide; tin-based oxides such as fluorine-doped tin oxide; and zinc-based oxides such as zinc aluminum oxide.

[0057] Step S502: A barrier layer is formed on a portion of the surface of the first transparent conductive layer on the side away from the substrate.

[0058] Specifically, the barrier layer can be made of materials such as silicon oxide, aluminum oxide, and rare earth metal oxides, which can block ions in the first anti-reaction reaction. In practical applications, the barrier layer can be deposited using processes such as chemical vapor deposition (CVD), physical vapor deposition (PVD), and atomic layer deposition (ALD).

[0059] Step S503: A first anti-reflection layer is formed on the side of the barrier layer away from the first transparent conductive layer;

[0060] The material of the first antireflective layer can be at least one of magnesium fluoride, lithium fluoride, and sodium fluoride.

[0061] Step S504: A first metal layer is formed on the side of the first transparent conductive layer away from the substrate and / or on the side of the first antireflective layer away from the barrier layer. The first transparent conductive layer, the barrier layer, the first antireflective layer and the first metal layer form a back reflector structure.

[0062] The material of the first metal layer can be at least one of metals such as gold, silver, copper, and aluminum. The back reflector structure is an optical functional layer located on one side of the bottom of the cell. Its main function is to reflect long-wavelength photons that penetrate the absorption layer back into the cell, achieving secondary or multiple absorption, thereby improving photoelectric conversion efficiency and reducing material usage. In practical applications, long-wavelength photons (650~1200 nm) are difficult to completely capture by the thin absorption layer in silicon-based thin-film tandem cells (such as amorphous silicon / microcrystalline silicon tandem cells). The back reflector reflects these photons through optical interference or photon bandgap effect, which can more than double the optical path length. Furthermore, the short-circuit current of the tandem cell is limited by the cell with the smallest current. The back reflector structure can selectively enhance the long-wavelength absorption of the bottom cell, helping to achieve current matching between the top and bottom cells and improving overall output. By reusing light energy, the thickness of the microcrystalline silicon bottom cell can be reduced while maintaining the absorption rate, lowering material costs and mitigating light-induced degradation effects.

[0063] In step S505, an intermediate layer and a perovskite top cell are sequentially formed on the side of the substrate away from the back reflector structure.

[0064] The intermediate layer connects the top and bottom cells. This intermediate layer can also serve as a charge transport layer (CTL), functioning to perform electrical coupling and carrier recombination, optical management, and interface passivation. In a tandem cell, electrons (or holes) from the top cell recombine with holes (or electrons) from the bottom cell at the intermediate layer interface, forming an electrical series connection. In practical applications, this intermediate layer exhibits high tunneling current density and low resistance, ensuring that recombination does not become a limiting factor. Furthermore, the intermediate layer can achieve nanoscale thickness uniformity by replicating the substrate morphology, suppressing lateral leakage and preventing short circuits between the top and bottom cells.

[0065] This embodiment provides a method for fabricating a tandem solar cell. First, a substrate is provided, and a first transparent conductive layer is formed on one side of the substrate. A barrier layer is formed on a portion of the surface of the first transparent conductive layer away from the substrate. Then, a first antireflective layer is formed on the side of the barrier layer away from the first transparent conductive layer. Next, a first metal layer is formed on the side of the first transparent conductive layer away from the substrate and / or on the side of the first antireflective layer away from the barrier layer. The first transparent conductive layer, the barrier layer, the first antireflective layer, and the first metal layer form a back reflector structure. Finally, an intermediate layer and a perovskite top solar cell are sequentially formed on the side of the substrate away from the back reflector structure. This solution improves the stability of the tandem solar cell by placing a barrier layer between the first transparent conductive layer and the first antireflective layer in the back reflector structure of the bottom solar cell. This barrier layer prevents ions in the first antireflective layer from penetrating the first transparent conductive layer and entering the substrate, thereby preventing damage to the bottom solar cell structure and improving the stability of the tandem solar cell. This solves the technical problem of how to improve the stability of tandem solar cells.

[0066] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the method for preparing the stacked battery of this application will be described in detail below with reference to specific embodiments and comparative examples.

[0067] Example

[0068] This embodiment provides a stacked battery, including:

[0069] The bottom battery includes at least a substrate and a back reflector structure located on one side of the substrate. The back reflector structure includes a first transparent conductive layer, a barrier layer, a first anti-reflection layer, and a first metal layer. The barrier layer is located on the side of the first transparent conductive layer away from the substrate, the first anti-reflection layer is located on the side of the barrier layer away from the first transparent conductive layer, and the first metal layer is located on the side of the first anti-reflection layer away from the substrate and the side of the first transparent conductive layer away from the substrate, and is in contact with the first transparent conductive layer.

[0070] The intermediate layer is located on the side of the substrate away from the back reflector structure.

[0071] The perovskite top cell is located on the side of the aforementioned intermediate layer away from the aforementioned bottom cell.

[0072] Comparative Example

[0073] This embodiment provides a stacked battery, the only difference from the previous embodiment being that it does not include a barrier layer.

[0074] The performance of the tandem cells in the above embodiments and comparative examples was tested, and the test results are as follows: Figure 5 As shown, the performance test employs a 480-hour dual 85 dark-state storage test, also known as a constant temperature and humidity (high temperature and high humidity) test. The test conditions are 85℃ + 85% relative humidity, abbreviated as dual 85. This test primarily simulates the aging process of multilayer batteries under harsh environments, verifying whether the product can withstand long-term high temperature and humidity. The specific steps are as follows:

[0075] Step S1: Sample preparation, the stacked cell is in the dark (no light, no bias voltage) and in the "power off storage" state; stabilize it in 25°C / 50%RH environment for 2 hours to eliminate residual stress; test IV characteristics, EL image, PL strength, take appearance photos and record the baseline data;

[0076] Step S2: Test chamber preparation: constant temperature and humidity test chamber, accuracy ±1°C / ±3%RH; run unloaded for 30 minutes to confirm that the temperature and humidity are stable at 85±1°C / 85±3%RH; use deionized water with conductivity <5μS / cm to prevent contamination.

[0077] Step S3: Sample placement. Place the stacked battery sample to be tested in the sample holder with a spacing of ≥10cm to ensure airflow circulation; first heat to 85°C, then slowly increase humidity to 85%RH, and stabilize within 3 hours to avoid condensation on the sample surface; the stacked battery needs to be sealed in a test box filled with inert gas to simulate the actual packaging environment.

[0078] Step S4: Store continuously for 480 hours, during which the test chamber is kept constant at 85°C / 85%RH; record the temperature and humidity curves every 24 hours to ensure no overshoot; the sample is not powered or exposed to light throughout the process, and is only exposed to the environment.

[0079] Step S5: Within 480 hours, perform performance testing on the tandem solar cell to obtain power conversion efficiency (PCE) curves at different times, and obtain the results as shown below. Figure 5 The test results are shown.

[0080] from Figure 5 It can be seen that the photoelectric conversion efficiency of the embodiment is higher than that of the comparative example. Furthermore, during the 480-hour test, the photoelectric conversion efficiency of the comparative example decreased more than that of the embodiment, indicating that the tandem battery of this application can improve the performance of the tandem battery.

[0081] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0082] 1) The stacked solar cell of this application includes a bottom cell, an intermediate layer, and a perovskite top cell. The bottom cell includes at least a substrate and a back reflector structure located on one side of the substrate. The back reflector structure includes a first transparent conductive layer, a barrier layer, a first antireflective layer, and a first metal layer. The barrier layer is located on the side of the first transparent conductive layer away from the substrate, the first antireflective layer is located on the side of the barrier layer away from the first transparent conductive layer, and the first metal layer is located on the side of the first antireflective layer away from the substrate and / or the side of the first transparent conductive layer away from the substrate, and is in contact with the first transparent conductive layer. The intermediate layer is located on the side of the substrate away from the back reflector structure. The perovskite top cell is located on the side of the intermediate layer away from the bottom cell. This solution improves the stability of the stacked solar cell by setting a barrier layer between the first transparent conductive layer and the first antireflective layer in the back reflector structure of the bottom cell. This barrier layer is used to prevent ions in the first antireflective layer from passing through the first transparent conductive layer into the substrate, thereby preventing damage to the structure of the bottom cell and improving the stability of the stacked solar cell. This solves the technical problem of how to improve the stability of the stacked solar cell.

[0083] 2) The fabrication method of the stacked solar cell of this application includes: first, providing a substrate and forming a first transparent conductive layer on one side of the substrate; forming a barrier layer on a portion of the surface of the first transparent conductive layer away from the substrate; then forming a first antireflective layer on the side of the barrier layer away from the first transparent conductive layer; next, forming a first metal layer on the side of the first transparent conductive layer away from the substrate and / or the side of the first antireflective layer away from the barrier layer, wherein the first transparent conductive layer, the barrier layer, the first antireflective layer, and the first metal layer form a back reflector structure; finally, forming an intermediate layer and a perovskite top solar cell sequentially on the side of the substrate away from the back reflector structure. This solution solves the technical problem of how to improve the stability of stacked solar cells by setting a barrier layer between the first transparent conductive layer and the first antireflective layer in the back reflector structure of the bottom solar cell. This barrier layer is used to prevent ions in the first antireflective layer from passing through the first transparent conductive layer into the substrate, thereby preventing damage to the structure of the bottom solar cell and improving the stability of the stacked solar cell.

[0084] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The above description is merely a preferred embodiment of this application and is 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 stacked battery, characterized in that, include: A bottom battery includes at least a substrate and a back reflector structure located on one side of the substrate. The back reflector structure includes a first transparent conductive layer, a barrier layer, a first anti-reflection layer, and a first metal layer. The barrier layer is located on the side of the first transparent conductive layer away from the substrate, the first anti-reflection layer is located on the side of the barrier layer away from the first transparent conductive layer, and the first metal layer is located on the side of the first anti-reflection layer away from the substrate and / or on the side of the first transparent conductive layer away from the substrate, and is in contact with the first transparent conductive layer. The intermediate layer is located on the side of the substrate away from the back reflector structure; The perovskite top cell is located on the side of the intermediate layer away from the bottom cell.

2. The stacked battery according to claim 1, characterized in that, The blocking layer includes a plurality of blocking portions arranged at intervals, and the first antireflection layer includes a plurality of antireflection portions arranged at intervals.

3. The stacked battery according to claim 2, characterized in that, Along a direction perpendicular to the base, the width of the blocking portion is the same as the width of the anti-reflection portion.

4. The stacked battery according to claim 2, characterized in that, The blocking portion satisfies at least one of the following: Along a direction perpendicular to the base, the width of the blocking portion is 0.5mm to 1.5mm; Along a direction perpendicular to the substrate, the distance between any two adjacent blocking portions is 10μm to 100μm.

5. The stacked battery according to claim 2, characterized in that, In a predetermined direction, the orthographic projection of the blocking portion onto the first transparent conductive layer has a first boundary, the first transparent conductive layer has a second boundary, and the minimum distance between the first boundary and the second boundary is 1mm to 2mm, wherein the predetermined direction is perpendicular to the arrangement direction of the blocking portion.

6. The stacked battery according to claim 1, characterized in that, The material of the barrier layer includes one or more of silicon oxide, aluminum oxide, and rare earth metal oxides.

7. The stacked battery according to claim 1, characterized in that, The bottom battery satisfies at least one of the following: The thickness of the first antireflection layer is 150~300nm; The thickness of the barrier layer is 1nm to 30nm.

8. The stacked battery according to claim 1, characterized in that, The bottom battery also includes a second transparent conductive layer located between the substrate and the intermediate layer.

9. The stacked battery according to claim 1, characterized in that, In the direction from the bottom cell to the perovskite top cell, the perovskite top cell includes a perovskite substrate, a connecting layer, a transport layer, a buffer layer, a third transparent conductive layer, a second antireflection layer, and a second metal layer stacked sequentially.

10. A method for preparing a tandem battery according to any one of claims 1 to 9, characterized in that, include: A substrate is provided, and a first transparent conductive layer is formed on one side of the substrate; A barrier layer is formed on a portion of the surface of the first transparent conductive layer on the side away from the substrate; A first anti-reflection layer is formed on the side of the barrier layer away from the first transparent conductive layer; A first metal layer is formed on the side of the first transparent conductive layer away from the substrate and / or on the side of the first antireflective layer away from the barrier layer, and the first transparent conductive layer, the barrier layer, the first antireflective layer and the first metal layer form a back reflector structure; An intermediate layer and a perovskite top cell are sequentially formed on the side of the substrate away from the back reflector structure.

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