Perovskite laminated solar cell, preparation method thereof and photovoltaic module

Abstract

The invention discloses a perovskite laminated solar cell, a preparation method thereof and a photovoltaic module. The cell comprises a silicon substrate cell; a perovskite top cell; the perovskite top cell comprises a perovskite layer, a buffer layer and a transparent conductive layer, wherein the buffer layer is located between the perovskite layer and the transparent conductive layer; a composite layer located between the silicon substrate cell and the perovskite top cell; the buffer layer extends towards the direction close to the silicon substrate cell through the side surface, and at least covers the intersection of the perovskite layer and the side surface. According to the invention, the buffer layer fully protects the perovskite layer, improves the stability of the perovskite layer, improves the passivation effect and the protection effect on the perovskite layer, is easy to achieve mass production, and is lower in cost.

Description

Technical Field

[0001] This application belongs to the field of photovoltaic technology, specifically relating to a perovskite tandem solar cell, its preparation method, and a photovoltaic module. Background Technology

[0002] Perovskite solar cells have advantages such as high conversion efficiency, simple fabrication process and low cost potential, and have become thin-film solar cells with promising industrialization prospects.

[0003] Among them, perovskite tandem solar cells have seen rapid development due to their advantages of high cell conversion efficiency and low cost. For example, the theoretical photoelectric conversion efficiency of some perovskite tandem solar cells can reach over 30%.

[0004] However, the instability of the perovskite layer remains a significant factor restricting the large-area fabrication and widespread use of perovskite tandem solar cells. Summary of the Invention

[0005] This application aims to provide a perovskite tandem solar cell, its preparation method, and a photovoltaic module, at least solving the problem of instability of the perovskite layer in perovskite tandem solar cells.

[0006] In a first aspect, embodiments of this application propose a perovskite tandem solar cell, comprising: Silicon-based solar cells; A perovskite top solar cell, comprising a perovskite layer, a buffer layer, and a transparent conductive layer, wherein the buffer layer is located between the perovskite layer and the transparent conductive layer; A composite layer is located between the silicon substrate cell and the perovskite top cell; Along the thickness direction of the perovskite tandem solar cell, the perovskite tandem solar cell has a first surface and a second surface opposite to each other; the perovskite tandem solar cell also has a side surface connecting the first surface and the second surface; The buffer layer extends from the side toward the silicon substrate cell, covering at least the junction of the perovskite layer and the side.

[0007] In existing technologies, the portion where the perovskite layer intersects with the side surface is not covered by adjacent perovskite layers. In this application, a buffer layer is added to at least the intersection of the perovskite layer and the side surface. This buffer layer covers the uncovered portion of the perovskite layer in existing technologies, protecting the perovskite layer during transportation and packaging of the perovskite tandem solar cell, thus improving its stability. Especially when the buffer layer is formed using methods such as ALD (atomic layer densification), it becomes denser, significantly reducing side damage to the perovskite layer. Furthermore, this buffer layer, covering at least the side surface of the perovskite layer, can effectively isolate the perovskite tandem solar cell and the perovskite layer from external factors such as moisture, oxygen, and heat sources, further enhancing the stability of the perovskite layer and consequently improving the reliability of the perovskite tandem solar cell.

[0008] In some embodiments, the buffer layer extends to the junction of the composite layer and the side surface.

[0009] First, the buffer layer located between the transparent conductive layer and the composite layer extends to the junction of the composite layer and this side, i.e., it covers the side of the composite layer, thus physically isolating the composite layer and the transparent conductive layer. This prevents direct contact between the transparent conductive layer and the composite layer in the perovskite tandem solar cell, thereby reducing the risk of leakage. Second, compared to other films between the transparent conductive layer and the composite layer, when the buffer layer is formed using methods such as ALD, the buffer layer is denser and has a certain insulating effect, providing better physical isolation between the composite layer and the transparent conductive layer, further reducing the risk of leakage. Third, compared to other films between the transparent conductive layer and the composite layer, when the buffer layer is formed using methods such as ALD, the production capacity is higher, the process is mature and the cost is low. In the process of mass-producing the portion of the buffer layer located on the side of the composite layer, it has almost no impact on the uniformity of the buffer layer thickness of other cells, and also has almost no impact on the production efficiency of the perovskite tandem solar cell, making it suitable for mass production.

[0010] In some embodiments, the first side is close to the silicon substrate cell, and the second side is close to the perovskite top cell; The silicon substrate solar cell further includes: a doped layer located on the side of the silicon substrate closer to the first surface; The buffer layer extends to the junction of the doped layer and the side surface.

[0011] In some embodiments, the first side is close to the silicon substrate cell, and the second side is close to the perovskite top cell; The buffer layer extends and wraps around at least a portion of the first surface.

[0012] In some embodiments, the buffer layer comprises one or a combination of tin oxide, titanium oxide, or aluminum oxide.

[0013] In some embodiments, the perovskite top solar cell further includes a hole transport layer located between the composite layer and the perovskite layer, the hole transport layer extending from the side surface toward the silicon substrate solar cell and covering at least a portion of the side surface; or... The perovskite top solar cell further includes: an antireflection layer located on the side of the transparent conductive layer away from the composite layer; the antireflection layer extends from the side towards the silicon substrate solar cell, covering at least a portion of the side.

[0014] In some embodiments, the antireflective layer extends to the junction of the perovskite layer and the side surface.

[0015] In some embodiments, the thickness of the buffer layer covering the side is H1, where H1 is greater than or equal to 3 nm.

[0016] In some embodiments, H1 is less than or equal to 20 nm.

[0017] In some embodiments, H1 gradually decreases along the direction toward the silicon substrate.

[0018] In some embodiments, along the thickness direction of the perovskite tandem solar cell, the silicon substrate includes opposing third and fourth surfaces, and the silicon substrate cell further includes a doped layer and a passivation layer located on at least one of the third and fourth surfaces. At least one of the doped layer and the passivation layer covers the junction of the silicon substrate and the side surface.

[0019] Secondly, embodiments of this application propose a method for fabricating a perovskite tandem solar cell, comprising: Provide silicon-based solar cells; A composite layer is formed on the silicon substrate cell; A perovskite layer, a buffer layer, and a transparent conductive layer are sequentially formed on the composite layer; The buffer layer is formed by fully exposing the surface to be deposited before forming the buffer layer, using atomic layer deposition, vapor deposition, or magnetron sputtering, preferably atomic layer deposition.

[0020] Thirdly, embodiments of this application propose a photovoltaic module, including an electrical connector and a plurality of the aforementioned perovskite tandem solar cells, wherein the electrical connector is used to electrically connect adjacent perovskite tandem solar cells.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a front view schematic diagram of a perovskite tandem solar cell according to an embodiment of this application; Figure 2 This is a side view of a perovskite tandem solar cell according to an embodiment of this application; Figure 3 This is a partial side SEM image of a silicon substrate solar cell according to an embodiment of this application; Figure 4 This is a partial side SEM image of a silicon substrate cell in a perovskite tandem solar cell according to an embodiment of this application; Figure 5 This is a partial side EDS image of a silicon substrate cell in a perovskite tandem solar cell according to an embodiment of this application; Figure 6 This is a partial side elemental analysis diagram of a silicon substrate cell in a perovskite tandem solar cell according to an embodiment of this application.

[0023] Figure label: 1-First interface passivation layer, 2-N-type doped layer, 3-P-type doped layer, 4-Back conductive layer, 5-Composite layer, 6-Hole transport layer, 7-Perovskite layer, 8-Second interface passivation layer, 9-Electron transport layer, 10-Buffer layer, 11-Transparent conductive layer, 12-Antireflection layer, 13-Electrode structure, 14-First side, 15-Second side, 16-Side side, 20-Silicon substrate. Detailed Implementation

[0024] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0025] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0026] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0028] This application provides a perovskite tandem solar cell, which includes a silicon substrate cell and a perovskite top cell. (Refer to...) Figure 1 Along the thickness direction Z of the perovskite tandem solar cell, the perovskite tandem solar cell has a first surface 14 and a second surface 15 facing each other, and a side surface 16 connecting the first surface 14 and the second surface 15. Of the first surface 14 and the second surface 15, one is the front or light-facing surface of the perovskite tandem solar cell, and the other is the back or backlight surface. During normal operation of the perovskite tandem solar cell, the surface that primarily absorbs light is its front or light-facing surface, while the back surface is opposite to the front surface, or the front surface is closer to the light source than the back surface. For example, the present application... Figure 1 and Figure 2 In this paper, the first side 14, which is the back side of the perovskite tandem solar cell, will be used as an example for explanation.

[0029] Reference Figure 1 and Figure 2The silicon-based solar cell includes a silicon substrate 20, and there are no limitations on the crystal phase or doping of the silicon substrate 20. The perovskite top solar cell includes a perovskite layer 7, which can be made of a material with an ABX3 structure. A can be one or more combinations of Cs (cesium), Rb (rubidium), CH3NH3 (methylammonium ion or methylamine ion), HC(NH2)2 (formamidine ion), CH3(CH2)3NH3 (butylamine ion), and (C6H5)(CH2)2NH3 (phenylethylammonium ion); B can be one of Pb (lead), Sn (tin), and Ge (germanium); and X can be a halogen element, specifically one or more of I (iodine), Br (bromine), or Cl (chlorine), such as MAPbBr3 (methylamine bromide perovskite), FAPbI3 (formamidine triiodohydrolead hydroxide), and (FA... 0.8 Cs 0.2 )Pb(I 0.7 Br 0.3 )3 (formamidinium cesium lead iodide bromide perovskite), (FA 0.85 Cs 0.15 )Pb(I 0.7 Br 0.3 The perovskite layer 7, made of materials such as formamidinium cesium lead iodide bromide perovskite, can be prepared using methods such as solution spin coating, inkjet printing, spraying, or slot coating. The perovskite layer 7 primarily absorbs light to generate photogenerated carriers (electron-hole pairs). This perovskite tandem solar cell includes a composite layer 5 located between the silicon substrate cell and the perovskite top cell. The composite layer 5 can be made of transparent conductive oxide (TCO), such as one or more combinations of ITO (indium tin oxide), IZO (indium zinc oxide), IWO (indium-doped tungsten oxide), ICO (indium cerium oxide), and GZO (gallium zinc oxide). It can be prepared using methods such as PVD (physical vapor deposition, such as magnetron sputtering) and RPD (reactive plasma deposition). The composite layer 5 primarily collects and recombines carriers and connects the silicon substrate cell and the perovskite top cell.

[0030] In some embodiments, refer to Figure 1 and Figure 2 Since the perovskite layer 7 completely covers the silicon substrate cell, the area of ​​the silicon substrate cell is not wasted and is all effective power generation area, which can improve the power generation efficiency of the perovskite tandem solar cell.

[0031] It should be noted that the perovskite layer 7 completely covers the silicon substrate cell. This can mean that the perovskite layer 7 and the film structure located in the perovskite top cell completely cover the silicon substrate cell. For example, the perovskite layer 7, hole transport layer 6, and electron transport layer 9 can all completely cover the silicon substrate cell. Specifically, the projection of the perovskite layer 7 covers the silicon substrate cell at corresponding positions on the first and second surfaces. The projection mentioned in this application refers to the projection of the corresponding structure onto the first and second surfaces when illuminated by light parallel to the thickness direction Z of the perovskite tandem solar cell. Side surface 16 refers to the surface located between the first surface 14 and the second surface 15 in the perovskite tandem solar cell.

[0032] Reference Figure 1 and Figure 2 The perovskite top solar cell further includes a buffer layer 10 and a transparent conductive layer 11. The buffer layer 10 is located between the perovskite layer 7 and the transparent conductive layer 11. The buffer layer 10 extends from the side surface 16 towards the silicon substrate solar cell, covering at least to the junction of the perovskite layer 7 and the side surface 16. This junction may include a location where the buffer layer 10 is in direct contact with the perovskite layer 7, or a location where there are other films between the buffer layer 10 and the perovskite layer 7, and the buffer layer 10 is in indirect contact with the side surface of the perovskite layer 7. The materials of these other films are not limited. The junction of the perovskite layer 7 and the side surface 16 refers to the location of the perovskite layer 7 within the side surface 16. The definition of the side surface of other structures mentioned in this application is similar, and will not be repeated here to avoid repetition.

[0033] Reference Figure 2On the side 16 of the perovskite tandem solar cell, the buffer layer 10 contacts the perovskite layer 7, thus directly and physically covering the side of the perovskite layer 7. This design serves two purposes: firstly, it isolates the perovskite layer 7 from erosion by moisture, oxygen, and heat sources from the side, protecting the side of the perovskite tandem solar cell and the perovskite layer 7 during transportation and packaging, thereby improving the stability of the perovskite layer 7. Especially when the buffer layer is formed using methods such as ALD, the buffer layer is more dense, significantly reducing damage to the perovskite layer 7 and the side of the perovskite tandem solar cell. Furthermore, this buffer layer, at least covering the side of the perovskite layer 7 of the perovskite tandem solar cell, can also significantly isolate the perovskite tandem solar cell and the perovskite layer 7 from external factors such as moisture, oxygen, and heat sources, particularly effectively protecting the sensitive perovskite layer 7, further improving the stability of the perovskite layer 7, and consequently enhancing the reliability of the perovskite tandem solar cell. Secondly, compared to other edge protection methods, the preparation process of the buffer layer 10 is simple, mature, and low-cost, making it suitable for mass production. Thirdly, the buffer layer 10, which covers at least the sides of the perovskite layer 7 of the perovskite tandem solar cell, can also provide passivation for at least a portion of the sides of the perovskite tandem solar cell, thereby reducing recombination and improving its performance. Fourthly, the formation of the transparent conductive layer 11 typically causes bombardment damage to the surrounding film layers. The buffer layer 10 can protect the underlying film layers, reducing the bombardment damage during the formation of the transparent conductive layer 11. Simultaneously, it can also protect at least a portion of the sides of the perovskite tandem solar cell, particularly the sides of the perovskite layer 7, thereby reducing the bombardment damage to at least a portion of the sides of the perovskite tandem solar cell and the sides of the perovskite layer 7 during the formation of the transparent conductive layer 11, and improving the performance of the perovskite tandem solar cell.

[0034] It should be noted that the perovskite layer 7 can extend towards the silicon substrate cell, covering at least part of the side 16. The specific location to which the perovskite layer 7 extends is not limited, but the buffer layer 10 will cover the perovskite layer 7 to fully protect it.

[0035] In some embodiments, the buffer layer 10 comprises tin oxide and titanium oxide (TiO2). x ) or aluminum oxide (AlO x One or more combinations of the following. The buffer layer 10 can be prepared by methods such as ALD, vapor deposition, PVD (magnetron sputtering), for example, it can be formed by ALD in this application. The x in the chemical formula of this application is greater than 0.

[0036] It should be noted that the material and preparation method of the transparent conductive layer 11 can refer to the material and preparation method of the aforementioned composite layer 5, and will not be repeated here. The transparent conductive layer 11 mainly serves as the carrier carrier... Figure 1 The main function is the collection and lateral transport of electrons, which are then led from the other end of the battery to the electrode structure 13. The electrode structure 13 mentioned in this application can be one or a combination of several metal materials with good conductivity, such as Ag (silver), Cu (copper), and Al (aluminum). It can be prepared by methods such as vapor deposition, magnetron sputtering, and screen printing. Its function is to lead the generated current from both ends of the battery for use by external electrical appliances, etc.

[0037] It should be noted that, Figure 2 It can be Figure 1 A partially enlarged schematic diagram, Figure 2 It is mainly used to demonstrate the relevant structures on the side of perovskite tandem solar cells.

[0038] In some embodiments, refer to Figure 2 The buffer layer 10 covers the junction of the composite layer 5 and the side surface 16. This junction may involve direct contact between the buffer layer 10 and the composite layer 5, or there may be other film layers between the buffer layer 10 and the composite layer 5, with indirect contact between the buffer layer 10 and the side surface of the composite layer 5. The materials of these other film layers are not limited. Specifically, the composite layer 5 is typically made of a transparent conductive oxide. Both the composite layer 5 and the transparent conductive layer 11 have a certain lateral conductivity, and their side contact could easily lead to leakage or even a short circuit. To address the above technical problems, this application addresses this issue by having the buffer layer 10, located between the transparent conductive layer 11 and the composite layer 5, cover the junction of the composite layer 5 and the side surface 16. This physically isolates the composite layer 5 and the transparent conductive layer 11, meaning they cannot directly contact each other, thus reducing the risk of leakage. Secondly, compared to other films between the transparent conductive layer 11 and the composite layer 5, when the buffer layer 10 is formed using methods such as ALD, the buffer layer 10 is denser and has a certain insulating effect, providing better physical isolation between the composite layer 5 and the transparent conductive layer 11, further reducing the risk of leakage. Thirdly, compared to other films between the transparent conductive layer 11 and the composite layer 5, when the buffer layer 10 is formed using methods such as ALD, the production capacity is higher, and the process is mature and low-cost. During the mass production process of forming the side portion of the buffer layer, it has almost no impact on the uniformity of the buffer layer thickness of each cell, and also has almost no impact on the production efficiency of the perovskite tandem solar cell, making it suitable for mass production.

[0039] In this application, the other film layers between the transparent conductive layer 11 and the composite layer 5 mainly refer to: electron transport layer, hole transport layer, second interface passivation layer, etc. The electron transport layer 9 can be one or a combination of C60, PCBM (methyl phenyl-C61-butyrate), SnO2, etc., and can be prepared by vapor deposition, mainly for collecting and transporting generated electrons. The hole transport layer 6 can be organic materials such as Sprio-OMeTAD (2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene), Sprio-TTB (spiropyran-TTB), TATM (triaminotriazine), P3HT (poly(3-hexylthiophene)), PEDOT (poly(3,4-ethylenedioxythiophene)), Me-4PACz ([4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid), MoO x (Molybdenum oxide), NiO x The perovskite layer 7 can be prepared using one or more of the following inorganic materials: nickel oxide, cuprous oxide, etc., and can be prepared by solution spin coating, inkjet printing, vapor deposition, etc., mainly for collecting and transporting generated holes. The second interface passivation layer 8 can be prepared using one or more of the following: BCP (bath copper phosphate), Al2O3 (aluminum oxide), TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene), Cs2O3 (cesium oxide), LiF (lithium fluoride), etc., and can be prepared by vapor deposition, mainly for passivating defects on the surface of the perovskite layer 7.

[0040] It should be noted that this application does not limit the specific type of perovskite tandem solar cell, the number of layers, the specific type of silicon-based cell, or the specific type of perovskite top cell. For example, Figure 1 The perovskite tandem solar cell shown is a perovskite top cell / silicon-based heterojunction tandem solar cell. This perovskite tandem solar cell has a high photoelectric conversion efficiency. Meanwhile, silicon-based heterojunction solar cells have advantages such as simple process, low preparation temperature, high conversion efficiency, symmetrical structure, high infrared absorption, and strong weak light effect. When stacked with the perovskite top cell, the absorption of the solar spectrum can be distributed, and higher conversion efficiency is expected to be obtained. Figure 1 and Figure 2 The perovskite tandem solar cell shown is merely illustrative; all perovskite tandem solar cells containing a perovskite layer, a composite layer, a buffer layer, and a transparent conductive layer are within the scope of this application. For example, regarding... Figure 1 and Figure 2 In the corresponding perovskite tandem solar cell, the electron transport layer and hole transport layer can be swapped, and similarly, the N-type doped layer 2 and the P-type doped layer 3 need to be swapped.

[0041] In some embodiments, refer to Figure 1 and Figure 2 The first side 14 is close to the silicon substrate cell, and the second side 15 is close to the perovskite top cell. Alternatively, the first side 14 can be considered the back side of the perovskite tandem solar cell, and the second side 15 can be considered the front side. The silicon substrate cell may further include a doped layer located on the side of the silicon substrate 20 close to the first side 14. This doped layer may include an N-type doped layer and / or a P-type doped layer. On the side 16 of the perovskite tandem solar cell, a buffer layer 10 covers the junction of the doped layer and the side 16. Thus, the buffer layer 10 further expands the passivation range of the perovskite tandem solar cell's side surface, reducing bombardment damage.

[0042] It should be noted that the N-type doped layer 2 can be prepared by phosphorus doping using phosphorus diffusion / printing paste, etc., mainly for electron extraction and collection. The P-type doped layer 3 can be prepared by boron doping using boron diffusion / printing paste, etc., mainly for hole extraction and collection.

[0043] In some embodiments, refer to Figure 1 and Figure 2 The first side 14 is close to the silicon substrate cell, and the second side 15 is close to the perovskite top cell. Alternatively, the first side 14 can be considered as the back side of the perovskite tandem solar cell, and the second side 15 as the front side of the perovskite tandem solar cell. The buffer layer 10 extends and wraps around at least part of the first side 14.

[0044] Specifically, refer to Figure 1 and Figure 2 A back conductive layer 4 may also be provided on the side near the first surface 14 to facilitate the lateral conduction and collection of charge carriers such as holes, which are then led out from one end of the cell to the electrode structure 13. In order to avoid leakage or short circuit between the transparent conductive layer 11, the composite layer 5 and the back conductive layer 4, the buffer layer 10 extends to at least part of the first surface 14 and covers the back conductive layer 4. This avoids leakage or short circuit due to the back conductive layer 4 and also provides good protection and passivation for the first surface 14 located outside the perovskite tandem solar cell, further improving the reliability of the perovskite tandem solar cell.

[0045] It should be noted that, for Figure 1 and Figure 2 In the perovskite tandem solar cell shown, the first surface can be the surface of the back conductive layer 4 facing away from the silicon substrate 20. The buffer layer 10 can also provide good protection and passivation for the surface of the back conductive layer 4 facing away from the silicon substrate 20. The specific size and proportion of the buffer layer 10 covering the first surface 14 are not limited.

[0046] In some embodiments, the perovskite top solar cell further includes a hole transport layer 6, which is located between the composite layer 5 and the perovskite layer 7. The hole transport layer 6 extends from the side surface 16 toward the silicon substrate solar cell, covering at least a portion of the side surface 16. Firstly, the hole transport layer 6 covering the side surface can protect the side surface of the perovskite tandem solar cell during transportation and encapsulation, reducing damage to the side surface. Simultaneously, the hole transport layer 6 covering the side surface of the perovskite tandem solar cell can also isolate it from external factors such as moisture, oxygen, and heat sources, thereby improving the reliability of the perovskite tandem solar cell.

[0047] In some embodiments, refer to Figure 1 and Figure 2 The perovskite top solar cell may further include an antireflection layer 12, located on the side of the transparent conductive layer 11 away from the composite layer 5. The antireflection layer 12 extends from the side surface 16 towards the silicon substrate cell, covering at least a portion of the side surface 16. Firstly, this antireflection layer 12, covering at least a portion of the side surface of the perovskite tandem solar cell, can provide passivation to at least a portion of the side surface, thereby reducing recombination in the perovskite tandem solar cell and improving its performance. Secondly, the antireflection layer 12 has a mature manufacturing process; during the mass production process of forming the side portion of the antireflection layer, it has almost no impact on the uniformity of the antireflection layer thickness of each cell, and also has almost no impact on the production efficiency of the perovskite tandem solar cell, making it suitable for mass production.

[0048] Antireflection layer 12 can be MgF2 (magnesium fluoride), LiF (lithium fluoride), or SiO2. x (Silicon oxide), SiN x One or more of silicon nitride and other materials can be used to prepare the battery by methods such as vapor deposition, PECVD, LPCVD, and magnetron sputtering (PVD). Its main function is to reduce light reflection and allow more light to enter the battery and be utilized.

[0049] In some embodiments, where the antireflection layer 12 covers the junction of the perovskite layer 7 and the side surface 16, the antireflection layer 12 can protect the perovskite layer 7, significantly isolating it from external factors such as water vapor, oxygen, and heat sources, thereby further improving the reliability of the perovskite tandem solar cell.

[0050] It should be noted that the size or size ratio of the antireflective layer 12 covering the perovskite layer 7 on the side 16 is not limited.

[0051] In some embodiments, refer to Figure 2The thickness H1 of the buffer layer 10 covering the side 16 is greater than or equal to 3 nm and less than or equal to the thickness H2 of the buffer layer 10 projected onto the first surface 14. Specifically, if H1 is too small, its protection of the side and its effect on reducing leakage current are poor; if H1 is too large, the process time for forming the buffer layer 10 will be too long, affecting production efficiency. Therefore, in this application, the thickness H1 is within the above range, which not only does not affect production efficiency, but also provides good protection of the side and reduces leakage current.

[0052] It should be noted that H1 represents the thickness of the buffer layer 10 covering any position on side 16, and the direction of this thickness can be perpendicular to side 16. The thickness at each position can be within the aforementioned thickness range. H2 represents the average thickness of the buffer layer 10 projected onto the first surface 14, and the direction of this thickness can be parallel to the thickness direction Z of the perovskite tandem solar cell. H2 can be the arithmetic mean of the thicknesses at two or more positions. The thickness values ​​corresponding to H1 and H2 in this application can be measured by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

[0053] For example, the thickness H1 of the buffer layer 10 covering the side 16 can be 3nm, 4nm, 4.5nm, 5nm, 6nm, 7nm, 7.3nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 18nm, or 20nm.

[0054] In some embodiments, refer to Figure 2 Along the direction close to the silicon substrate 20, H1 gradually decreases. The thickness of the buffer layer 10 covering the side 16 varies according to the above pattern. The buffer layer 10 covering the side 16 can be formed by appropriate wrapping deposition on the side 16 during the formation of the buffer layer 10, which is a simple process. It should be noted that compared with processes such as specially preparing insulating layers on the side, this application does not require additional equipment for preparing insulating layers on the side, thus reducing equipment costs. Moreover, the process steps of this application are simpler, which is conducive to mass production. Compared with cutting or laser processing of the parts on the side that have the risk of leakage or short circuit, this application does not require cutting or laser processing, and will not cause serious damage to the edge passivation of the perovskite tandem solar cell. Therefore, this application can improve the passivation performance of the cell.

[0055] It should be noted that along the direction close to the silicon substrate 20, H1 can gradually decrease in the manner of exponential thinning, linear thinning, etc., and there is no limitation on the thinning method.

[0056] In some embodiments, refer to Figure 1 and Figure 2Along the thickness direction Z of the perovskite tandem solar cell, the silicon substrate 20 includes opposing third and fourth surfaces, one of which is the front side of the silicon substrate 20, and the other is its back side. During normal operation of the perovskite tandem solar cell, the surface of the silicon substrate 20 that primarily receives light is its front side. For example, Figure 1 In this configuration, the surface of the silicon substrate 20 closest to the perovskite top cell is its front side, and the surface of the silicon substrate 20 opposite to the perovskite top cell is its back side. The silicon substrate cell also includes: a doped layer and a passivation layer located on at least one of the third and fourth surfaces of the silicon substrate 20; the doped layer ( Figure 2 The N-type doped layer 2 and the P-type doped layer 3 shown, along with at least one of the passivation layer, cover the junction of the silicon substrate 20 and the side surface 16, i.e., cover the side surface of the silicon substrate 20. Therefore, firstly, the side surface of the silicon substrate 20 can be protected during transportation and encapsulation of the perovskite tandem solar cell, further improving the reliability of the perovskite tandem solar cell. Secondly, at least one of the doped layer and passivation layer covering the side surface of the silicon substrate 20 can also provide passivation to the side surface of the silicon substrate 20, thereby reducing recombination in the perovskite tandem solar cell and improving its performance.

[0057] It should be noted that the doped layer here may include an N-type doped layer 2 and / or a P-type doped layer 3. The passivation layer here may include at least one of an interface passivation layer and a surface passivation layer. The interface passivation layer is typically located between the doped layer and the silicon substrate, and the surface passivation layer is typically located on the side of the doped layer away from the silicon substrate. For example, Figure 1 and Figure 2 The passivation layer in the text can refer to the first interface passivation layer 1, which can be hydrogenated intrinsic amorphous silicon SiO2. x (Silicon oxide), AlO x One or more of the following can be used to prepare the substrate: alumina, etc. It can be prepared by plate / tube PECVD (plasma-enhanced chemical vapor deposition) / ALD / LPCVD (low-pressure chemical vapor deposition) to passivate defects on the surface of silicon substrate 20 and reduce recombination of photogenerated carriers at the interface.

[0058] This application also provides a method for fabricating a perovskite tandem solar cell, comprising: Step S1: Provide a silicon-based solar cell.

[0059] The fabrication method of silicon-based solar cells can refer to existing related fabrication processes for silicon-based solar cells, and no specific limitations are imposed.

[0060] Step S2: A composite layer is formed on the silicon substrate cell; a perovskite layer, a buffer layer, and a transparent conductive layer are sequentially formed on the composite layer; wherein, the surface to be deposited is fully exposed before the buffer layer is formed, and the buffer layer is formed by atomic layer deposition, vapor deposition, or magnetron sputtering, preferably atomic layer deposition.

[0061] Specifically, atomic layer deposition (ALD), vapor deposition, or magnetron sputtering methods offer high throughput, mature processes, and are suitable for mass production. They also provide better side protection and reduce leakage risk. The buffer layer formed by ALD is denser. Furthermore, by fully exposing the surface to be deposited before forming the buffer layer, the accompanying edge deposition extends towards the silicon substrate during the buffer layer formation process, at least covering the junction of the perovskite layer and the side surface. During buffer layer deposition, the coverage area and thickness of the buffer layer material on the side of the perovskite tandem solar cell can be controlled by adjusting the deposition rate or by locally applying side masks. Compared to other edge protection methods, the buffer layer fabrication process described in this application is simple, mature, and low-cost, making it suitable for mass production.

[0062] It should be noted that this preparation method can produce any of the aforementioned perovskite tandem solar cells. When it is necessary to add any layer to the aforementioned method, the step of preparing that layer should be added accordingly. Other steps of this preparation method can be referred to in related technologies, and will not be repeated here.

[0063] The following is combined Figure 1 and Figure 2 The perovskite tandem solar cell shown here is roughly described in terms of its fabrication method. The first step is to provide an N-type silicon substrate with a thickness of 200-250 μm. After wet cleaning, the surface dirt and cutting damage layer of the silicon substrate are removed. Then, double-sided texturing is performed to form a pyramid shape of uniform size on both sides of the silicon substrate.

[0064] The second step involves sequentially depositing a first interface passivation layer 1 using plate-type PECVD to passivate surface defects and dangling bonds on the silicon substrate 20, reducing recombination of photogenerated carriers at this interface, depositing an N-type doped layer 2 to form a back-side field passivation layer, and depositing a P-type doped layer 3 to form a silicon substrate battery PN junction.

[0065] In the third step, magnetron sputtering is used to deposit a 50nm-130nm ITO layer on the P-type doped layer 3 prepared in the second step as a back conductive layer 4, which laterally transports the holes generated by the silicon substrate cell to the electrode structure 13. To prevent leakage caused by the back conductive layer 4 being deposited around the side of the cell, a mask is set at the edge of the cell during deposition; at the same time, a 7-14nm ITO layer is deposited on the N-type doped layer 2 as a composite layer 5.

[0066] In the fourth step, silver grid lines are printed on the back conductive layer 4 prepared in the third step using screen printing to form the electrode structure 13 on the backlight side. For the composite layer 5, after the electrode structure 13 on the backlight side is dried and cured, a 7-14 nm layer of ITO can be deposited on the N-type doped layer 2 prepared in the third step using magnetron sputtering to collect holes and electrons and connect the silicon substrate cell and the perovskite top cell.

[0067] After the fourth step of preparation is completed, SEM images of the side of the silicon substrate cell are generated. See the attached image for details. Figure 3 SEM images refer to images obtained using a scanning electron microscope. Figure 3 The highest highlighted part is the location of the slope on the side.

[0068] In the fifth step, a 10-15 nm hole transport layer 6 is prepared on the composite layer 5 prepared in the fourth step using solution spin coating. This separates the electron-hole pairs generated by the perovskite layer and guides the holes out. A 0.7-1.0 μm perovskite layer 7 is then spin-coated onto the hole transport layer 6 to serve as the light-absorbing layer of the perovskite top solar cell. This layer primarily absorbs light in the mid-to-short wavelength range, generating photogenerated carriers. The perovskite layer 7 covers the composite layer on the side, physically isolating the composite layer from the subsequent transparent conductive layer.

[0069] The sixth step involves depositing 3-5 nm of LiF onto the perovskite layer 7 prepared in the fifth step as a second interface passivation layer 8 to passivate defects on the surface of the perovskite layer 7 and reduce the recombination of photogenerated carriers at this interface.

[0070] In the seventh step, a 5-10 nm layer of C60 is deposited on the second interface passivation layer 8 prepared in the sixth step as an electron transport layer 9 to separate the electron-hole pairs generated by the perovskite layer and export the electrons.

[0071] Step 8: Without using a mask to block the sides of the electron transport layer 9, the surface of the electron transport layer 9 facing away from the second interface passivation layer 8 is completely exposed. A 10-20 nm layer is then fabricated on the electron transport layer 9 prepared in step 7 using ALD. Figure 2SnO2 (H2) in the buffer layer 10 is used as a buffer layer to reduce the damage to the underlying film layer caused by the deposition of the transparent conductive layer 11. When preparing the buffer layer 10, the buffer layer 10 is deposited around the side of the battery (and may even be deposited around the first side 14 of the battery). The thickness H1 of the buffer layer 10 covering the side is 3-20nm. The buffer layer 10 covers at least the perovskite layer 7 through the side. The buffer layer 10 covering the side can also isolate the composite layer 5 and the transparent conductive layer on the side, reduce the leakage current of the battery, and protect the perovskite layer 7 on the side from external factors such as water vapor, oxygen, and heat sources, thereby improving the reliability of the battery. The buffer layer 10 covering the side can cover the side of the P-type doped layer 3, which can reduce the bombardment damage to the side film layer during the deposition of the transparent conductive layer 11 and improve the passivation effect of the battery side.

[0072] In the ninth step, a 20-50 nm layer of IZO is deposited on the buffer layer 10 prepared in the eighth step using magnetron sputtering or RPD as a transparent conductive layer 11, which laterally transports the electrons generated by the perovskite top cell to the light-facing electrode structure 13.

[0073] In the tenth step, silver grid lines are printed on the transparent conductive layer 11 deposited in the ninth step to form an electrode structure 13 facing the light side. After curing and drying, 100nm-130nm MgF2 is deposited as an anti-reflection layer 12 to reduce the reflection of incident light and allow more sunlight to enter the battery and be absorbed.

[0074] After the tenth step of fabrication is completed, SEM images of the side surface of the silicon substrate cell in the perovskite tandem solar cell are generated. See the attached image for details. Figure 4 .contrast Figure 3 and Figure 4 It can be concluded that Figure 4 The corresponding perovskite tandem solar cell has material that clearly covers the side of the silicon substrate cell. Figure 4 The uppermost highlighted part and Figure 3 The location corresponds to the part of the slope on the side.

[0075] against Figure 4 EDS (Energy Dispersive X-ray Spectroscopy) analysis was performed on the side of the silicon substrate cell in the corresponding perovskite tandem solar cell. See the attached EDS image for details. Figure 5 The elemental distribution on the side of the perovskite tandem solar cell is referenced. Figure 6 .pass Figures 3 to 6 It can be concluded that the perovskite tandem solar cell is covered by at least a perovskite layer 7 and a buffer layer 10 on its sides. The buffer layer 10 protects the perovskite layer 7 from interference from water vapor, oxygen, heat sources, etc., thus improving the reliability of the perovskite tandem solar cell. EDS refers to energy dispersive spectroscopy.

[0076] It should be noted that, Figure 5 The upper part and Figure 3 , Figure 4 The location of the uppermost slope corresponds to the location of the slope, and because the height of this slope varies, therefore... Figure 5 The upper part may be subject to signal interference. Figure 6 The smaller proportion of elements may be the result of signal interference. Figure 6 In this context, At refers to the percentage of atoms on the side of the silicon substrate in a perovskite tandem solar cell. Figure 6 The highest mass percentage of silicon (Si) indicates that this side is the side corresponding to the silicon substrate cell in the perovskite tandem solar cell. The high mass percentages of carbon (C), hydrogen (H), and oxygen (O) indicate that this side is covered with a perovskite layer. The high mass percentages of oxygen (O) and tin (Sn) indicate that this side is covered with a buffer layer (SnO2).

[0077] This application also provides a photovoltaic module, which includes an electrical connector and a plurality of any of the aforementioned perovskite tandem solar cells. The electrical connector is used to electrically connect adjacent perovskite tandem solar cells. The electrical connector may be a structure such as a solder strip, and the specific form of the electrical connector is not limited.

[0078] The perovskite tandem solar cell, the fabrication method of the perovskite tandem solar cell, and the photovoltaic module provided in this application are related to each other. To avoid duplication, the relevant parts will not be described again.

[0079] It should be noted that the embodiments of this application can be implemented in combination or individually without contradiction, and all of them are within the protection scope of this application.

[0080] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0081] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A perovskite tandem solar cell, comprising: Silicon-based solar cells; A perovskite top solar cell, comprising a perovskite layer, a buffer layer, and a transparent conductive layer, wherein the buffer layer is located between the perovskite layer and the transparent conductive layer; A composite layer is located between the silicon substrate cell and the perovskite top cell; Along the thickness direction of the perovskite tandem solar cell, the perovskite tandem solar cell has a first side and a second side opposite to each other, and the perovskite tandem solar cell also has a side side connecting the first side and the second side; The buffer layer extends from the side toward the silicon substrate cell, covering at least the junction of the perovskite layer and the side.

2. The perovskite tandem solar cell according to claim 1, characterized in that, The buffer layer extends to the junction of the composite layer and the side surface.

3. The perovskite tandem solar cell according to claim 1, characterized in that, The first side is close to the silicon substrate cell, and the second side is close to the perovskite top cell; The silicon substrate solar cell further includes: a doped layer located on the side of the silicon substrate closer to the first surface; The buffer layer extends to the junction of the doped layer and the side surface.

4. The perovskite tandem solar cell according to claim 1, characterized in that, The first side is close to the silicon substrate cell, and the second side is close to the perovskite top cell; The buffer layer extends and wraps around at least a portion of the first surface.

5. The perovskite tandem solar cell according to claim 1, characterized in that, The buffer layer comprises one or a combination of tin oxide, titanium oxide, or aluminum oxide.

6. The perovskite tandem solar cell according to claim 1, characterized in that, The perovskite top solar cell further includes a hole transport layer located between the composite layer and the perovskite layer, the hole transport layer extending from the side toward the silicon substrate solar cell and covering at least a portion of the side. or, The perovskite top solar cell further includes: an antireflection layer located on the side of the transparent conductive layer away from the composite layer; The antireflective layer extends from the side toward the silicon substrate cell, covering at least a portion of the side.

7. The perovskite tandem solar cell according to claim 6, characterized in that, The antireflective layer extends to the junction of the perovskite layer and the side surface.

8. The perovskite tandem solar cell according to claim 1, characterized in that, The thickness of the buffer layer covering the side is H1, and H1 is greater than or equal to 3 nm.

9. The perovskite tandem solar cell according to claim 8, characterized in that, The H1 is less than or equal to 20 nm.

10. The perovskite tandem solar cell according to claim 8, characterized in that, H1 gradually decreases along the direction toward the silicon substrate.

11. The perovskite tandem solar cell according to any one of claims 1 to 6, characterized in that, Along the thickness direction of the perovskite tandem solar cell, the silicon substrate includes opposing third and fourth surfaces, and the silicon substrate cell further includes a doped layer and a passivation layer located on at least one of the third and fourth surfaces. At least one of the doped layer and the passivation layer covers the junction of the silicon substrate and the side surface.

12. A method for fabricating a perovskite tandem solar cell, characterized in that, include: Provide silicon-based solar cells; A composite layer is formed on the silicon substrate cell; A perovskite layer, a buffer layer, and a transparent conductive layer are sequentially formed on the composite layer; The buffer layer is formed by fully exposing the surface to be deposited before forming the buffer layer, using atomic layer deposition, vapor deposition, or magnetron sputtering, preferably atomic layer deposition.

13. A photovoltaic module, comprising an electrical connector and several claims 1 The perovskite tandem solar cell according to any one of 11, wherein the electrical connector is used for electrically connecting adjacent perovskite tandem solar cells.

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