Solar cell and photovoltaic module

Abstract

The invention discloses a solar cell and a photovoltaic module, relates to the technical field of photovoltaics, and is used for solving the problem of poor carrier transport and recombination performance of a composite layer. The solar cell comprises: a crystalline silicon bottom cell; a plurality of parallel top electrodes are arranged on a first light incident surface, far away from the crystalline silicon bottom battery, of the thin film top battery; the composite layer is located between the crystalline silicon bottom battery and the thin film top battery, and the crystalline silicon bottom battery and the thin film top battery are electrically connected through the composite layer; wherein the composite layer comprises a first transparent conductive layer and a first hole transport layer which are stacked, and the first transparent conductive layer and the first hole transport layer are arranged on the whole surface of the solar cell; the composite layer further comprises a second transparent conductive layer and a second hole transport layer which are patterned and stacked, and the projection area of the second transparent conductive layer and the projection area of the second hole transport layer on the first light incident surface are overlapped with the projection area of the top electrode on the first light incident surface.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and more particularly to a solar cell and a photovoltaic module. Background Technology

[0002] Tandem solar cells are solar cells formed by stacking semiconductor cells with different bandgap widths together, which can maximize the energy utilization of sunlight and improve the photoelectric conversion efficiency of solar cells.

[0003] In crystalline silicon / thin-film tandem solar cells, the intermediate recombination layer plays a crucial role in further improving cell efficiency, primarily serving as the efficient recombination layer for majority carriers in the top and bottom cells. Current two-terminal tandem solar cells typically employ tunneling junctions, transparent conductive carbon (TCO) layers, or metal layers as the intermediate recombination layer. However, current intermediate recombination layers often suffer from poor electron-hole recombination or low transmittance for long-wavelength light, resulting in insufficient fill factor. Therefore, improvements to the intermediate recombination layer are needed to enhance the conversion efficiency of solar cells. Summary of the Invention

[0004] The purpose of this invention is to provide a solar cell and a photovoltaic module that improves the intermediate recombination layer, enhances the carrier transport performance and recombination in the dark region below the top electrode, and improves the conversion efficiency of the solar cell.

[0005] In a first aspect, the present invention provides a solar cell, comprising: Crystalline silicon bottom cells; A thin-film top cell has a first light-incident surface on the side away from the crystalline silicon bottom cell, and a plurality of parallel top electrodes are disposed on the first light-incident surface. A composite layer is located between the crystalline silicon bottom cell and the thin-film top cell, and the crystalline silicon bottom cell and the thin-film top cell are electrically connected through the composite layer. The composite layer includes a first transparent conductive layer and a first hole transport layer stacked together, and the first transparent conductive layer and the first hole transport layer are disposed on the entire surface of the solar cell. The composite layer also includes a patterned and stacked second transparent conductive layer and a second hole transport layer. The second transparent conductive layer has multiple spaced first projection regions on the first light-incident surface, and the second hole transport layer has multiple spaced second projection regions on the first light-incident surface. Multiple parallel top electrodes have multiple spaced third projection regions on the first light-incident surface. The extension direction of the first projection region is parallel to the extension direction of the top electrode, and the extension direction of the second projection region is parallel to the extension direction of the top electrode. The first projection region overlaps with the second projection region, and both the first projection region and the second projection region overlap with the third projection region.

[0006] In the above technical solution, the composite layer includes a first transparent conductive layer and a first hole transport layer disposed across the entire surface, and a second transparent conductive layer and a second hole transport layer disposed partially. The second transparent conductive layer has multiple spaced-apart first projection regions on the first light-receiving surface, the second hole transport layer has multiple spaced-apart second projection regions on the first light-receiving surface, and multiple parallel top electrodes have multiple spaced-apart third projection regions on the first light-receiving surface. The extension direction of the first projection regions is parallel to the extension direction of the top electrodes, and the extension direction of the second projection regions is parallel to the extension direction of the top electrodes. The first and second projection regions overlap, and the first and second projection regions overlap with the third projection regions. Because the top electrodes are on the first light-receiving surface of the thin-film top cell, they partially block sunlight irradiated from the first light-receiving surface. Therefore, there are areas in the composite layer corresponding to the top electrodes that are not illuminated, forming dark areas. Areas outside the top electrodes on the first light-receiving surface are not blocked from sunlight, and sunlight enters the composite layer, forming illuminated areas. In the illuminated areas, a large number of electrons generated by the crystalline silicon bottom cell rapidly diffuse to the dark areas due to the difference in concentration gradient. However, for thin-film top-mounted solar cells, the lateral transport capability of holes generated in the hole transport layer is weak, obstructing the hole transport path and reducing the recombination rate between holes and electrons in the dark region. This leads to a large accumulation of electrons in the dark region, causing local band bending and increasing the potential barrier for carrier transport. Consequently, the cell has a lower flyback distance (FF) and volume of charge (Voc). For cell stability, the accumulation of a large number of electrons may accelerate interface degradation or ion migration, reducing cell performance. Therefore, in this application, a patterned second transparent conductive layer and a second hole transport layer are disposed in the dark region, which can increase the lateral transport of holes and provide a dedicated channel for the recombination of electrons and holes in the dark region. This enables electrons in the dark region to recombine with holes quickly, reducing electron accumulation in the dark region. The first transparent conductive layer and the first hole transport layer are disposed across the entire surface, increasing the contact area between holes and electrons, improving the recombination probability, and achieving efficient recombination of electrons and holes.

[0007] In some possible implementations, the thin-film top cell is a perovskite top cell.

[0008] In some possible implementations, the ratio of the sum of the areas of the multiple first projection regions to the sum of the areas of the multiple second projection regions is 1.2:1 to 1:1.2; or, The sum of the areas of multiple first projection regions or the sum of the areas of multiple second projection regions accounts for 50% to 110% of the sum of the areas of multiple third projection regions, respectively.

[0009] In some possible implementations, the boundary of the first projection region or the boundary of the second projection region is recessed and / or extends beyond the boundary of the third projection region, respectively, and the recessed and / or extended distance is 0% to 10% of the width of the top electrode.

[0010] In some possible implementations, the width of the first projection region or the second projection region is 20μm to 60μm, respectively.

[0011] In some possible implementations, the thickness of the first transparent conductive layer is 1 nm to 20 nm; And / or, the thickness of the first hole transport layer is 1nm~5nm; And / or, the thickness of the second transparent conductive layer is 1nm~200nm, preferably 1nm~50nm; And / or, the thickness of the second hole transport layer is 1nm~200nm, preferably 1nm~50nm.

[0012] In some possible implementations, the first transparent conductive layer includes one or more of indium tin oxide, indium zinc oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, boron-doped zinc oxide, indium gallium zinc oxide, and antimony-doped titanium dioxide; And / or, the second transparent conductive layer includes one or more of indium tin oxide, indium zinc oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, boron-doped zinc oxide, indium gallium zinc oxide, and antimony-doped titanium dioxide.

[0013] In some possible implementations, the first hole transport layer includes 2PACz, MeO-4PACz, Me-4PACz, MeO-2PACz, MeO-6PACz, PTAA, NiO x One or more of the following; And / or, the second hole transport layer includes 2PACz, MeO-4PACz, Me-4PACz, MeO-2PACz, MeO-6PACz, PTAA, NiO x One or more of them.

[0014] In some possible implementations, the second transparent conductive layer is in contact with the crystalline silicon bottom cell, the second hole transport layer is in contact with the first transparent conductive layer, the portion of the first transparent conductive layer outside the third projection region is in contact with the crystalline silicon bottom cell, and the first hole transport layer is in contact with the perovskite top cell. Alternatively, the second hole transport layer is in contact with the perovskite top cell, the second transparent conductive layer is in contact with the first hole transport layer, the portion of the first hole transport layer outside the third projection region is in contact with the perovskite top cell, and the first transparent conductive layer is in contact with the crystalline silicon bottom cell.

[0015] In some possible implementations, when the second transparent conductive layer is in contact with the crystalline silicon bottom cell, the first hole transport layer is a monomolecular self-assembled layer; and / or, when the second hole transport layer is in contact with the perovskite top cell, the second hole transport layer is a monomolecular self-assembled layer.

[0016] In some possible implementations, when the second transparent conductive layer is in contact with the crystalline silicon bottom cell, the first hole transport layer includes one or more of 2PACz, MeO-4PACz, Me-4PACz, MeO-2PACz, and MeO-6PACz; or, When the second hole transport layer is in contact with the perovskite top cell, the second hole transport layer includes one or more of 2PACz, MeO-4PACz, Me-4PACz, MeO-2PACz, and MeO-6PACz.

[0017] Among some possible implementations, the crystalline silicon bottom cell is one of the following: passivated emitter back cell, heterojunction cell, back contact cell, back contact heterojunction cell, and tunneling oxide passivated contact cell.

[0018] Secondly, the present invention also provides a photovoltaic module, comprising: A battery string, which is formed by electrically connecting a plurality of solar cells as described in any of the above; Interconnectors are electrically connected to the solar cells; And an encapsulation layer that covers the surface of the battery string.

[0019] Since photovoltaic modules use solar cells described in any of the above descriptions, they have the same beneficial effects as the aforementioned solar cells, and will not be elaborated further. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 A top view schematic diagram of a solar cell provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a first composite layer of a solar cell provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the projection area of ​​the top electrode, the second hole transport layer, and the second transparent conductive layer of a solar cell provided in an embodiment of the present invention on the first light-incident surface. Figure 4 This is a schematic diagram of the structure of a second composite layer in a solar cell provided in an embodiment of the present invention; Figure 5 A schematic diagram of a composite layer structure provided in the prior art; Figure 6 This is a schematic diagram of another composite layer structure provided in the prior art.

[0021] Reference numerals: 1 is the top electrode, 2 is the thin-film top cell, 3 is the composite layer, 31 is the first hole transport layer, 32 is the first transparent conductive layer, 33 is the second hole transport layer, 34 is the second transparent conductive layer, 35 is the metal layer, 301 is the first projection area, 302 is the second projection area, 303 is the third projection area, 4 is the crystalline silicon bottom cell, and 5 is the back electrode. Detailed Implementation

[0022] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0023] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0025] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] In crystalline silicon / thin-film tandem solar cells, the intermediate recombination layer plays a crucial role in further improving cell efficiency, primarily serving as the efficient recombination layer for majority carriers in the top and bottom cells. Existing two-terminal tandem solar cells typically employ tunneling junctions, transparent conductive carbon (TCO) layers, and metal layers as the intermediate recombination layer. The tunneling junction is significantly affected by the subsequent fabrication process of the thin-film top cell. For example, organic solvents used in perovskite fabrication can easily damage the tunneling junction's performance, resulting in a poor fill factor (FF). The TCO layer is primarily n-type, with a higher electron conductivity than hole conductivity, leading to more electron accumulation at the tandem solar cell interface. This electrons cannot balance recombination with holes, resulting in a poor FF and low open-circuit voltage (Voc). The metal layer generally has higher reflectivity, significantly affecting the transmission of long-wavelength light, resulting in a low short-circuit current (Jsc) in the tandem solar cell. Furthermore, for existing inverted thin-film / crystalline silicon tandem solar cells, i.e., thin-film top cells, the hole transport layer is close to the recombination layer. In their existing recombination layer structure, the shading of the top electrode on the light-incident surface of the cell leads to the formation of dark and illuminated areas in the recombination layer region. In the illuminated area, a large number of electrons generated by the silicon bottom cell diffuse rapidly to the dark area due to the concentration gradient difference. However, for inverted thin-film top cells, the lateral resistance of holes generated by the thin-film top cell on the hole transport layer is much greater than that of the transparent conductive layer, which obstructs the hole transport path. This increases the series resistance of the cell and reduces the recombination rate between holes and electrons in the dark area, leading to a large accumulation of electrons in the dark area. The accumulated electrons cause local band bending, increasing the potential barrier for carrier transport, resulting in a lower flyback distance (FF) and Voc. For cell stability, the accumulation of a large number of electrons may accelerate interface degradation or ion migration, deteriorating device performance.

[0028] In view of this, such as Figures 1-4As shown, this embodiment of the invention provides a solar cell, including a crystalline silicon bottom cell 4, a thin-film top cell 2, and a composite layer 3. The thin-film top cell 2 has multiple parallel top electrodes 1 disposed on its first light-incident surface away from the crystalline silicon bottom cell 4. Each top electrode 1 can be a current collector electrode for collecting charge carriers. The multiple current collector electrodes are parallel to each other, extend along a first direction, and are spaced apart along a second direction. The first and second directions can be perpendicular. The composite layer 3 is located between the crystalline silicon bottom cell 4 and the thin-film top cell 2, and the crystalline silicon bottom cell 4 and the thin-film top cell 2 are electrically connected through the composite layer 3. The composite layer 3 includes a first transparent conductive layer 32 and a first hole transport layer 31 stacked together. The first transparent conductive layer 32 and the first hole transport layer 31 are disposed on the entire surface of the solar cell, i.e., covering the crystalline silicon bottom cell 4 or the thin-film top cell 2. The entire surface of the membrane top cell 2; the composite layer 3 further includes a patterned and stacked second transparent conductive layer 34 and a second hole transport layer 33. The second transparent conductive layer 34 has multiple spaced first projection regions 301 on the first light-incident surface, and the second hole transport layer 33 has multiple spaced second projection regions 302 on the first light-incident surface. Multiple parallel top electrodes 1 have multiple spaced third projection regions 303 on the first light-incident surface. The extending direction of the first projection region 301 is parallel to the extending direction of the top electrode 1, and the extending direction of the second projection region 302 is parallel to the extending direction of the top electrode 1. The first projection region 301 and the second projection region 302 overlap, and both the first projection region 301 and the second projection region 302 overlap with the third projection region 303. Figure 2 , Figure 3 and Figure 4 As shown, a portion of each third projection region 303 overlaps with the corresponding first projection region 301 and second projection region 302, or all of each third projection region 303 overlaps with the corresponding first projection region 301 and second projection region 302; the first projection region 301 and second projection region 302 can also completely overlap or partially overlap. That is, at least a portion of the composite layer 3 located directly below the top electrode 1 is provided with the second transparent conductive layer 34 and the second hole transport layer 33. The second transparent conductive layer 34 and the second hole transport layer 33 can be partially or completely disposed within the third projection region 303 of the top electrode 1. The projection region on the first light-incident surface refers to a two-dimensional planar projection along the thickness direction of the solar cell onto the first light-incident surface. The first light-incident surface is a plane perpendicular to the thickness direction of the solar cell, and the projection region can be understood as a two-dimensional planar region.

[0029] It is understood that the thin-film top cell 2 can be a perovskite top cell, a copper indium gallium selenide cell, a microcrystalline silicon cell, a nanocrystalline silicon cell, an indium phosphide cell, an amorphous silicon cell, a gallium arsenide cell, or a cadmium telluride cell.

[0030] It is understood that the top electrode 1 is typically strip-shaped, and the third projection region 303 of multiple parallel top electrodes 1 on the first incident light surface consists of multiple spaced strip-shaped regions. The first projection region 301 and the second projection region 302 can be of any shape, as long as they overlap with the third projection region 303. From the perspective of facilitating fabrication and controlling the degree of overlap between the first projection region 301, the second projection region 302, and the third projection region 303, the first projection region 301 and the second projection region 302 are preferably strip-shaped.

[0031] When the above technical solution is adopted, the composite layer 3 includes a first transparent conductive layer 32 and a first hole transport layer 31 disposed on the entire surface, and a second transparent conductive layer 34 and a second hole transport layer 33 disposed in a patterned manner. The first projection area 301 of the second transparent conductive layer 34 on the first light-receiving surface and the second projection area 302 of the second hole transport layer 33 on the first light-receiving surface overlap with the third projection area 303 of the top electrode 1 on the first light-receiving surface. Therefore, at least a portion of the composite layer 3 located directly below the top electrode 1 contains a four-layer structure consisting of the first transparent conductive layer 32, the first hole transport layer 31, the second transparent conductive layer 34, and the second hole transport layer 33. The area of ​​the composite layer 3 outside the area directly below the top electrode contains a two-layer structure consisting of the first transparent conductive layer 32 and the first hole transport layer 31. Since the top electrode 1 is located on the first light-incident surface of the thin-film top cell 2, it partially blocks sunlight from shining through the first light-incident surface. Therefore, there is a dark area in the composite layer 3 corresponding to the position of the top electrode 1, which is not illuminated by sunlight (corresponding to the third projection area 303 of the top electrode 1 on the first light-incident surface). However, the area outside the top electrode 1 on the first light-incident surface is not blocked from sunlight, and sunlight enters the composite layer 3 to form an illuminated area (corresponding to the area outside the third projection area 303 of the top electrode 1 on the first light-incident surface). In the illuminated area, a large number of electrons generated by the crystalline silicon bottom cell 4 will rapidly diffuse to the dark area due to the difference in concentration gradient. However, for the thin-film top cell 2, the holes generated by the thin-film top cell 2 have a weak lateral transport capability on the hole transport layer, which obstructs the hole transport path, reduces the recombination rate of holes and electrons in the dark area, and causes a large accumulation of electrons in the dark area. The accumulated electrons cause local band bending, increase the potential barrier for carrier transport, and thus the cell has a low fill factor (FF) and open circuit voltage (Voc). In terms of cell stability, the accumulation of a large number of electrons may accelerate interface degradation or ion migration and reduce cell performance. Therefore, the patterned second hole transport layer 33 in this application is disposed in the dark area blocked by the top electrode 1, which can increase the lateral transport of holes. The patterned second transparent conductive layer 34 disposed in the dark area blocked by the top electrode 1 can extract electrons from the crystalline silicon bottom cell 4, so that holes in the illuminated area are laterally transported to the second hole transport layer 33 in the dark area through the first transparent conductive layer 32. Holes recombine with electrons from the crystalline silicon bottom cell 4 in the second hole transport layer 33 and the second transparent conductive layer 34, which enables electrons in the dark area to recombine with holes quickly, providing a dedicated channel for electron-hole recombination in the dark area and reducing electron accumulation in the dark area. This can reduce optical loss caused by light absorption and enable electrons in the dark area to recombine with holes quickly, reducing electron accumulation in the dark area. The first transparent conductive layer 32 and the first hole transport layer 31 are disposed on the entire surface, increasing the contact area between holes and electrons. Therefore, the recombination probability is increased, and efficient recombination of electrons and holes is achieved.

[0032] like Figures 2-4 As shown, in some embodiments, the ratio of the sum of the areas of the plurality of first projection regions 301 to the sum of the areas of the plurality of second projection regions 302 is 1.2:1 to 1:1.2, specifically 1.2:1, 1.1:1, 1:1, 1:1.1, 1:1.2, etc. That is, the sum of the areas of all the first projection regions 301 of the second transparent conductive layer 34 is similar to the sum of the areas of all the second projection regions 302 of the second hole transport layer 33, making the second transparent conductive layer 34 and the second hole transport layer 33 essentially completely overlap. This maximizes the utilization of the electron-hole transport channel formed by the second transparent conductive layer 34 and the second hole transport layer 33 in the dark area, enabling electrons in the dark area to recombine with holes quickly and reducing electron accumulation in the dark area.

[0033] In some embodiments, the sum of the areas of the plurality of first projection regions 301, or the sum of the areas of the plurality of second projection regions 302, accounts for 50% to 110% of the sum of the areas of the plurality of third projection regions 303, specifically 50%, 60%, 70%, 80%, 90%, 100%, 110%, etc. When the sum of the areas of the first projection regions 301 of the second transparent conductive layer 34 or the sum of the areas of the second projection regions 302 of the second hole transport layer 33 is less than 50%, the area of ​​the second transparent conductive layer 34 and the second hole transport layer 33 located in the dark region is too small, which is not conducive to the lateral transport of holes into the dark region, not conducive to the recombination of electrons and holes in the dark region, cannot effectively reduce the accumulation of electrons in the dark region, and cannot effectively improve the battery conversion efficiency. When the sum of the areas of the first projected regions 301 of the second transparent conductive layer 34 and the second projected regions 302 of the second hole transport layer 33 exceeds 110%, the first projected regions 301 or 302 extend excessively beyond the third projected region 303 on the first light-incident surface of the top electrode 1. This increases manufacturing costs. Furthermore, the second transparent conductive layer 34 and the second hole transport layer 33 encroach on the area of ​​the illuminated region, stacking with the first transparent conductive layer 32 and the first hole transport layer 31 in the illuminated region, increasing the transport paths of holes and electrons in the illuminated region and affecting carrier transport and recombination efficiency. Therefore, considering the combined transport and recombination efficiency of carriers in the dark and illuminated regions, the sum of the areas of multiple first projected regions 301 and the sum of the areas of second projected regions 302 is chosen to be between 50% and 110%.

[0034] like Figures 2-4As shown, in some embodiments, on the composite layer 3, corresponding to a position below a top electrode 1, the boundary of the first projection region 301 or the boundary of the second projection region 302 is recessed and / or extends beyond the boundary of the third projection region 303, and the recessed and / or extended distance is 0% to 10% of the width of the top electrode, specifically 0%, 2%, 4%, 6%, 8%, 10%, etc. The boundary of the first projection region 301 refers to the closed edge formed by the side of the first projection region 301 parallel to its extension direction and the side parallel to its width direction; similarly, the boundary of the second projection region 302 refers to the closed edge formed by the side of the second projection region 302 parallel to its extension direction and the side parallel to its width direction; similarly, the boundary of the third projection region 303 refers to the closed edge formed by the side of the third projection region 303 parallel to its extension direction and the side parallel to its width direction, which can also be the closed edge formed by the side of the top electrode 1 parallel to its extension direction and the side parallel to its width direction. Boundary convergence and / or extrapolation refers to the fact that, in the same direction, such as the extension direction or width direction of each projection area, at least a portion of the edge of one projection area parallel to its extension direction converges inward and / or extends outward along a direction perpendicular to the extension direction (i.e., along the width direction) to the corresponding edge of another projection area; or, at least a portion of the edge of one projection area parallel to its width direction converges inward and / or extends outward along a direction perpendicular to the width direction (i.e., along the extension direction) to the corresponding edge of another projection area. When both the first projection area 301 and the second projection area 302 are strip-shaped or nearly strip-shaped, the degree of overlap between the first projection area 301 and the second projection area 302 and the third projection area 303 can be measured by the degree of overlap of the boundaries of the projection areas. When the convergence and / or extrapolation distance is equal to 0% of the width of the top electrode 1 (collector electrode), the boundary of the first projection area 301 or the boundary of the second projection area 302 coincides with the boundary of the third projection area 303, and the shapes of the projection areas are consistent. When the inward distance exceeds 10% of the width of the top electrode 1, the area occupied by the second transparent conductive layer 34 and the second hole transport layer 33 in the dark region is too small. This is not conducive to the lateral transport of holes into the dark region, nor to the recombination of electrons and holes in the dark region. Consequently, it cannot effectively reduce electron accumulation in the dark region and cannot effectively improve the battery conversion efficiency. When the excess distance exceeds 10% of the width of the top electrode 1, the boundary of the first projection region 301 or the second projection region 302 exceeds the boundary of the third projection region 303 by too much. On the one hand, this increases the manufacturing cost of the second transparent conductive layer 34 and the second hole transport layer 33. On the other hand, the second transparent conductive layer 34 and the second hole transport layer 33 encroach on the area of ​​the illuminated region and are stacked with the first transparent conductive layer 32 and the first hole transport layer 31 in the illuminated region. This increases the transport path of holes and electrons in the illuminated region and affects the carrier transport and recombination efficiency.Therefore, considering the combined transport and recombination efficiency of charge carriers in the dark and illuminated regions, the distance by which the boundary of the first projection region 301 or the boundary of the second projection region 302 is recessed and / or extended relative to the boundary of the third projection region 303 is selected to be 0% to 10% of the width of the top electrode 1.

[0035] For example, the inward and / or outward distance is greater than or equal to 0 and less than or equal to 5 μm, depending on the different widths of the current collector electrodes.

[0036] like Figures 2-4 As shown, in some embodiments, the width of a first projection region 301 or a second projection region 302 is 20μm to 60μm, respectively. That is, the width of a second transparent conductive layer 34 or a second hole transport layer 33 located below a top electrode 1 is 20μm to 60μm. Since the second transparent conductive layer 34 and the second hole transport layer 33 are located in the dark area below the top electrode 1, the top electrode 1 is a collector electrode. The collector electrode is usually a gate line extending along a first direction, and multiple collector electrodes are arranged at intervals along a second direction. The first direction and the second direction are perpendicular. Therefore, the extension direction of the second transparent conductive layer 34 and the second hole transport layer 33 is the same as the extension direction of the current collector electrode, both extending along the first direction. Correspondingly, the first projection region 301 and the second projection region 302 both extend along the first direction. In the second direction perpendicular to the extension direction of the first projection region 301 and the second projection region 302, the width of the first projection region 301 and the second projection region 302 is 20μm to 60μm, specifically 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, etc. When the width is less than 20μm, the width of the second transparent conductive layer 34 and the second hole transport layer 33 located in the dark area below one top electrode 1 is too small, which is not conducive to the lateral transport of holes into the dark area, not conducive to the recombination of electrons and holes in the dark area, cannot effectively reduce electron accumulation in the dark area, and cannot effectively improve the battery conversion efficiency. When the width exceeds 60 μm, the width of the second transparent conductive layer 34 and the second hole transport layer 33, located in the dark region below the top electrode 1, becomes excessive. This increases manufacturing costs and encroaches on the illuminated area, stacking with the first transparent conductive layer 32 and the first hole transport layer 31 in the illuminated region. This increases the transport paths for holes and electrons in the illuminated region, affecting carrier transport and recombination efficiency. Therefore, considering the combined transport and recombination efficiency of carriers in both the dark and illuminated regions, the width of the second transparent conductive layer 34 and the second hole transport layer 33 is chosen to be between 20 μm and 60 μm.

[0037] In this application, the width of the first projection area 301 or the width of the second projection area 302 can be measured by scanning electron microscopy. Ten positions are randomly selected from the first projection area 301 or the second projection area 302 in the SEM image, their widths are measured, and then the arithmetic mean is calculated to obtain the width of the first projection area 301 or the width of the second projection area 302.

[0038] In some embodiments, the thickness of the first transparent conductive layer 32 is 1 nm to 20 nm, specifically 1 nm, 3 nm, 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, etc. If the thickness of the first transparent conductive layer 32 is less than 1 nm, the thickness is too small, the lateral flow resistance is too large, which is not conducive to the lateral transport of charge carriers. If the thickness of the first transparent conductive layer 32 is greater than 20 nm, the thickness is too large, which affects light transmission, increases material cost and preparation time cost, and increases the longitudinal transport path of charge carriers, which is not conducive to improving the carrier transport efficiency.

[0039] In some embodiments, the thickness of the first hole transport layer 31 is 1nm to 5nm, specifically 1nm, 2nm, 3nm, 4nm, 5nm, etc. If the thickness of the first hole transport layer 31 is less than 1nm, the thickness is too small, and holes cannot be effectively captured in time, reducing the carrier utilization rate. If the thickness of the first hole transport layer 31 is greater than 5nm, the thickness is too large, affecting light transmission, increasing material cost and preparation time cost, and increasing the longitudinal transport path of carriers, which is not conducive to improving carrier transport efficiency.

[0040] In some embodiments, the thickness of the second transparent conductive layer 34 is 1 nm to 200 nm, specifically 1 nm, 10 nm, 30 nm, 50 nm, 70 nm, 90 nm, 110 nm, 130 nm, 150 nm, 180 nm, 200 nm, etc. If the thickness of the second transparent conductive layer 34 is less than 1 nm, the thickness is too small, the lateral flow resistance is too large, which is not conducive to the lateral transport of charge carriers. If the thickness of the second transparent conductive layer 34 is greater than 200 nm, the thickness is too large, the material cost and preparation time cost increase, and the longitudinal transport path of charge carriers in the dark region increases, which is not conducive to improving the carrier transport efficiency. Preferably, the thickness of the second transparent conductive layer 34 is 1 nm to 50 nm, specifically 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0041] In some embodiments, the thickness of the second hole transport layer 33 is 1 nm to 200 nm, specifically 1 nm, 10 nm, 30 nm, 50 nm, 70 nm, 90 nm, 110 nm, 130 nm, 150 nm, 180 nm, 200 nm, etc. If the thickness of the second hole transport layer 33 is less than 1 nm, the thickness is too small, and the effect on modifying the interface energy level is limited, making it impossible to effectively adjust the surface work function of the transparent conductive layer, reduce the interface injection energy barrier of holes, and reduce the carrier transport rate. If the thickness of the second hole transport layer 33 is greater than 200 nm, the thickness is too large, increasing the material cost and fabrication time cost, and increasing the longitudinal transport path of carriers, which is not conducive to improving carrier transport efficiency. Preferably, the thickness of the second hole transport layer 33 is 1 nm to 50 nm, specifically 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc. The thickness of the second transparent conductive layer 34 and the second hole transport layer 33 is preferably less than or equal to 50 nm, so that these two layers do not produce obvious steps with the first transparent conductive layer 32 and the first hole transport layer 31, thereby reducing the impact on the film formation quality of the light absorption layer of the thin film top battery 2.

[0042] In some embodiments, the thin-film top cell 2 is a perovskite top cell, that is, the light-absorbing layer of the top cell is a perovskite material. The perovskite material can be an ABX3 type perovskite, where A includes monovalent cations such as CH3NH3, C4H9NH3, NH2=CHNH2 or Cs; B includes at least one divalent cation of lead or tin; and X includes at least one monovalent anion of iodine, bromine, or chloride.

[0043] Furthermore, the perovskite top solar cell can be an inorganic perovskite solar cell, an organic perovskite solar cell, or an organic-inorganic hybrid perovskite solar cell. For inorganic perovskite solar cells, A is Cs. + Ions; for organic perovskite batteries, A is one or more monovalent cations selected from CH3NH3, C4H9NH3, and NH2=CHNH2; for organic-inorganic hybrid perovskite batteries, A includes one or more monovalent cations selected from CH3NH3, C4H9NH3, and NH2=CHNH2, as well as Cs + .

[0044] For example, along the direction from the crystalline silicon bottom cell to the perovskite top cell, the perovskite top cell includes a perovskite light-absorbing layer, an electrically insulating layer, a carrier transport layer, a buffer layer, a fourth transparent conductive layer, and a top electrode, which are sequentially stacked. The carrier transport layer of the perovskite top cell is an electron transport layer, specifically a C0... 60The material can be one or more of the following: PCBM, SnO2, TiO2, ZnO, etc. The electrically insulating layer can be made of LiF, CaF2, NaF, MgF2, etc., and the buffer layer can be one or more of the following: SnO2, TiO2, ZnO, etc. The perovskite light-absorbing layer can be prepared from a perovskite precursor solution.

[0045] In some embodiments, for a perovskite top-mounted solar cell, the first transparent conductive layer 32 includes one or more of indium tin oxide, indium zinc oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, boron-doped zinc oxide, indium gallium zinc oxide, and antimony-doped titanium dioxide. The first transparent conductive layer 32 can be a single-layer structure or a multi-layer stacked structure, with each layer made of a different material.

[0046] In some embodiments, for a perovskite top-mounted solar cell, the second transparent conductive layer 34 includes one or more of indium tin oxide, indium zinc oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, boron-doped zinc oxide, indium gallium zinc oxide, and antimony-doped titanium dioxide. The second transparent conductive layer 34 can be a single-layer structure or a multi-layer stacked structure, with each layer made of a different material.

[0047] In some embodiments, for a perovskite top solar cell, the first hole transport layer 31 can be an organic hole transport material, such as 2PACz ((2-(9H-carbazole-9-yl)ethyl)phosphonic acid) or 4-PACz ((4-(9H-carbazole-9-yl)ethyl)phosphonic acid). MeO-4PACz ([4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphate), Me-2PACz ([2-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate), Me-4PACz ([4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate), MeO-2PACz (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid), MeO-6PACz (6-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid), PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine) or one or more of these, and the first hole transport layer 31 may also be NiO. x Materials include CuSCN, etc. The first hole transport layer 31 can be a single-layer structure or a multi-layer stacked structure, with each layer made of a different material.

[0048] In some embodiments, for a perovskite top solar cell, the second hole transport layer 33 can be an organic hole transport material, such as one or more of 2PACz, 4-PACz, MeO-4PACz, Me-2PACz, Me-4PACz, MeO-2PACz, MeO-6PACz, and PTAA. The second hole transport layer 33 can also be NiO. xCuSCN. The second hole transport layer 33 can be a single-layer structure or a multi-layer stacked structure, with each layer made of a different material.

[0049] like Figure 2 and Figure 3 As shown, in some embodiments, for inverted perovskite top cells, the perovskite top cell supplies holes as charge carriers for recombination to the composite layer 3. This embodiment provides a first composite layer structure, in which the second transparent conductive layer 34 is in contact with the crystalline silicon bottom cell 4, the second hole transport layer 33 is in contact with the first transparent conductive layer 32, the portion of the first transparent conductive layer 32 located outside the third projection region 303 is in contact with the crystalline silicon bottom cell 4, and the first hole transport layer 31 is in contact with the perovskite top cell. In other words, in the composite layer 3 located in the third projection region 303, that is, in the composite layer 3 located in the dark region, along the direction from the crystalline silicon bottom cell 4 to the perovskite top cell, a second transparent conductive layer 34, a second hole transport layer 33, a first transparent conductive layer 32, and a first hole transport layer 31 are sequentially stacked. The second transparent conductive layer 34 is in contact with the crystalline silicon bottom cell 4, and the first hole transport layer 31 is in contact with the perovskite top cell. In the composite layer 3 located outside the third projection region 303, that is, in the composite layer 3 located in the illuminated region, along the direction from the crystalline silicon bottom cell 4 to the perovskite top cell, a first transparent conductive layer 32 and a first hole transport layer 31 are sequentially stacked. The first transparent conductive layer 32 is in contact with the crystalline silicon bottom cell 4, and the first hole transport layer 31 is in contact with the perovskite top cell.

[0050] In this first type of composite layer, the recombination pathways of electrons and holes include two types, such as... Figure 2 As shown, the first recombination path mainly exists in the illuminated region, where holes from the perovskite top cell are transported to the first hole transport layer 31, and electrons from the N-type crystalline silicon bottom cell are transported to the first transparent conductive layer 32. Holes and electrons recombine at the interface between the first hole transport layer 31 and the first transparent conductive layer 32. The second recombination path mainly exists in the dark region. Holes generated in the illuminated region from the perovskite top cell reach the first transparent conductive layer 32 through the first hole transport layer 31. The first transparent conductive layer 32 contacts the second hole transport layer 33. Due to good energy level alignment, holes can efficiently transport laterally from the first transparent conductive layer 32 to the second hole transport layer 33, recombinating with electrons from the N-type crystalline silicon bottom cell in the second transparent conductive layer 34. The design of the second recombination path in the dark region effectively compensates for the charge accumulation phenomenon of the first recombination path in the dark region, thereby improving recombination efficiency, increasing the open-circuit voltage and fill factor of the solar cell, and improving conversion efficiency.

[0051] In this first type of composite layer, the first hole transport layer 31 preferably contains self-assembled molecular layers (SAMs), which have an interface energy level modification function. This function can precisely adjust the surface work function of the first transparent conductive layer 32, aligning the energy level of the first transparent conductive layer 32 with the valence band top energy level of the perovskite top solar cell. This reduces the interface injection barrier for holes, allowing holes generated from the illumination area of ​​the perovskite top solar cell to quickly reach the first transparent conductive layer 32 through the first hole transport layer 31.

[0052] Furthermore, the self-assembled molecular layers (SAMs) contain self-assembled small molecules with phosphate or silica anchoring groups, such as one or more of 2PACz, MeO-4PACz, Me-4PACz, MeO-2PACz, and MeO-6PACz.

[0053] like Figure 3 and Figure 4 As shown, in some other embodiments, this embodiment provides a second composite layer structure, in which a patterned second hole transport layer 33 contacts the perovskite top cell, a second transparent conductive layer 34 contacts the first hole transport layer 31, the portion of the first hole transport layer 31 located outside the third projection region 303 contacts the perovskite top cell, and the first transparent conductive layer 32 contacts the crystalline silicon bottom cell 4. Figure 2 Unlike the first composite layer structure, the second transparent conductive layer 34 and the second hole transport layer 33 have their stacking order reversed relative to the first transparent conductive layer 32 and the first hole transport layer 31. The second transparent conductive layer 34 and the second hole transport layer 33 are closer to the perovskite top cell. That is, in the composite layer 3 located in the third projection region 303, i.e., in the composite layer 3 located in the dark region, the first transparent conductive layer 32, the first hole transport layer 31, the second transparent conductive layer 34, and the second hole transport layer 33 are stacked sequentially along the direction from the crystalline silicon bottom cell 4 to the perovskite top cell. The first transparent conductive layer 32 is in contact with the crystalline silicon bottom cell 4, and the second hole transport layer 33 is in contact with the perovskite top cell. In the composite layer 3 located outside the third projection area 303, that is, in the composite layer 3 located in the illumination area, a first transparent conductive layer 32 and a first hole transport layer 31 are sequentially stacked along the direction from the crystalline silicon bottom cell 4 to the perovskite top cell. The first transparent conductive layer 32 is in contact with the crystalline silicon bottom cell 4, and the first hole transport layer 31 is in contact with the perovskite top cell.

[0054] In this second type of composite layer, the recombination pathways of electrons and holes include two types, such as... Figure 4As shown, the first recombination path mainly exists in the illuminated region, where holes from the perovskite top cell are transported to the first hole transport layer 31, and electrons from the N-type crystalline silicon bottom cell are transported to the first transparent conductive layer 32. Holes and electrons recombine at the interface between the first hole transport layer 31 and the first transparent conductive layer 32. The second recombination path mainly exists in the dark region, where holes from the perovskite top cell can reach the second transparent conductive layer 34 via the second hole transport layer 33 and / or the first hole transport layer 31 in the illuminated region. The second transparent conductive layer 34 transports holes, allowing them to reach the first hole transport layer 31 in the dark region, where they recombine with electrons from the crystalline silicon bottom cell 4 at the interface between the first transparent conductive layer 32 and the first hole transport layer 31. The design of the second recombination path in the dark region effectively compensates for the charge accumulation phenomenon of the first recombination path in the dark region, thereby improving recombination efficiency, increasing the open-circuit voltage and fill factor of the solar cell, and improving conversion efficiency.

[0055] In this second type of composite layer, the second hole transport layer 33 preferably includes self-assembled molecular layers (SAMs). The self-assembled molecular layers have an interface energy level modification effect, which can precisely adjust the surface work function of the second transparent conductive layer 34, so that the energy level of the second transparent conductive layer 34 is aligned with the valence band top energy level of the perovskite top cell, thereby reducing the interface injection energy barrier of holes and allowing holes generated from the perovskite top cell to quickly reach the second transparent conductive layer 34 through the second hole transport layer 33.

[0056] Furthermore, the self-assembled molecular layers (SAMs) contain self-assembled small molecules with phosphate or silica anchoring groups, such as one or more of 2PACz, MeO-4PACz, Me-4PACz, MeO-2PACz, and MeO-6PACz.

[0057] In some embodiments, the crystalline silicon bottom cell 4 can be one of a passivated emitter back cell, a heterojunction cell, a back contact cell, a back contact heterojunction cell, or a tunneling oxide passivated contact cell. Depending on the conductivity type, the crystalline silicon bottom cell can be an N-type crystalline silicon cell or a P-type crystalline silicon cell.

[0058] For example, when the crystalline silicon bottom cell is a heterojunction cell, the heterojunction cell, along the direction from the crystalline silicon bottom cell to the perovskite top cell, includes a back electrode 5, a third transparent conductive layer, a first doped conductive layer, a first passivation layer, a semiconductor substrate, a second passivation layer, and a second doped conductive layer, stacked sequentially. The second doped conductive layer is in contact with the composite layer. The semiconductor substrate can be any semiconductor material, such as a silicon substrate, a germanium-silicon substrate, a germanium substrate, or a gallium arsenide substrate.

[0059] When the heterojunction cell is an N-type cell, the semiconductor substrate has an N-type conductivity. The second doped conductive layer in contact with the composite layer can be an N-type doped conductive layer, specifically a phosphorus-doped microcrystalline silicon layer or an amorphous silicon layer, serving as the electron conductive layer. The second passivation layer can be an intrinsic amorphous silicon layer, and the intrinsic amorphous silicon layer and the phosphorus-doped microcrystalline silicon layer or amorphous silicon layer constitute a heterojunction structure. The first doped conductive layer can be a P-type doped conductive layer, specifically a boron-doped microcrystalline silicon layer or amorphous silicon layer, serving as the hole transport layer. The first passivation layer can also be an intrinsic amorphous silicon layer, forming a heterojunction structure with the boron-doped microcrystalline silicon layer or amorphous silicon layer. The material of the third transparent conductive layer can refer to the material of the first transparent conductive layer, and will not be described further.

[0060] When the heterojunction cell is a P-type cell, the semiconductor substrate is P-type conductive. The second doped conductive layer in contact with the composite layer is a P-type doped conductive layer, specifically a boron-doped microcrystalline silicon layer or an amorphous silicon layer, serving as a hole transport layer. The second passivation layer can be an intrinsic amorphous silicon layer. The intrinsic amorphous silicon layer and the boron-doped microcrystalline silicon layer or an amorphous silicon layer constitute a heterojunction structure. The first doped conductive layer can be an N-type doped conductive layer, specifically a phosphorus-doped microcrystalline silicon layer or an amorphous silicon layer, serving as an electron conductive layer. The first passivation layer can be an intrinsic amorphous silicon layer, which, together with the phosphorus-doped microcrystalline silicon layer or an amorphous silicon layer, constitutes a heterojunction structure.

[0061] The following comparative analysis uses multiple examples and comparative cases: Example 1, such as Figure 2 As shown, the method for fabricating the solar cell in this embodiment is as follows: Taking the crystalline silicon bottom cell 4 as an example of a heterojunction cell, the fabrication process of the crystalline silicon bottom cell 4 is as follows: Textured structures are grown on both sides of a silicon substrate using a wet chemical method. Intrinsic amorphous silicon layers are prepared on both sides of the textured structures using plasma-enhanced chemical vapor deposition (PECVD). A phosphorus-doped microcrystalline silicon layer or amorphous silicon layer is prepared on the light-incident side of the silicon substrate (near the perovskite top cell side) as an electronic conductive layer. A boron-doped amorphous silicon layer or microcrystalline silicon layer is prepared on the back-light side of the silicon substrate as a hole transport layer. A third transparent conductive layer is prepared on the hole transport layer side by plasma sputtering deposition. Finally, a metal electrode layer is prepared by thermal evaporation and screen printing as the back electrode 5.

[0062] Preparation process of composite layer 3: A composite layer 3 is fabricated on one side of the phosphorus-doped amorphous silicon layer or microcrystalline silicon layer of the crystalline silicon bottom cell 4. First, a patterned mask is covered on the phosphorus-doped amorphous silicon layer or microcrystalline silicon layer, wherein the pattern of the mask is consistent with the pattern of the top electrode 1 of the perovskite top cell, such as... Figure 1 and Figure 3As shown, the gate line of the top electrode 1 is located at the opening position of the mask pattern, and the width of the mask opening is less than or equal to the opening width of the gate line pattern. Next, a second transparent conductive layer 34 is prepared using ion sputtering or evaporation. The width of the projected area formed by one layer of the second transparent conductive layer 34 on the first incident light surface is 30 μm. The material of the second transparent conductive layer 34 is ITO with an electron mobility greater than 50 cm² / V·s, and the thickness is 50 nm. Then, a second hole transport layer 33 is prepared using sputtering or thermal evaporation. The material is NiOx, and the thickness is 50 nm. Finally, the mask is removed.

[0063] Next, a first transparent conductive layer 32 and a first hole transport layer 31 are fabricated. The first transparent conductive layer 32 is fabricated on the entire surface of a phosphorus-doped amorphous silicon layer or microcrystalline silicon layer using a sputtering method. The first transparent conductive layer 32 covers the second hole transport layer 33. The material of the first transparent conductive layer 32 is indium zinc oxide (IZO), and its thickness is 10 nm. Subsequently, the first hole transport layer 31 is fabricated on the first transparent conductive layer 32 by solution spin coating, immersion, or thermal evaporation. The material is MeO-4PACz, and its thickness is 5 nm.

[0064] Fabrication process of perovskite top solar cells: A perovskite light-absorbing layer is prepared by spin-coating on the first hole transport layer 31. For example, it can be prepared according to Cs... 0.05 FA 0.8 MA 0.15 Pb(I 0.75 Br 0.25 A perovskite precursor solution was prepared in a ratio of 3, and then the perovskite precursor solution was spin-coated onto the first hole transport layer 31. After that, it was annealed at 120°C for 15 min. The thickness of the perovskite light-absorbing layer prepared was 1 μm. Next, an electrically insulating layer of approximately 1 nm thickness was thermally evaporated and deposited on the perovskite light-absorbing layer using LiF. Then, C was thermally evaporated and deposited on the electrically insulating layer. 60 An electron transport layer with a thickness of about 15 nm is formed. An atomic layer deposition (ALD) technique is used to prepare a buffer layer on the electron transport layer. The material is SnO2 and the thickness is 18 nm. A third transparent conductive layer with a thickness of 30 nm is deposited on the buffer layer using PVD. Metal Ag is deposited or screen-printed on the third transparent conductive layer as the top electrode 1. MgF2 is deposited on the top electrode 1 as an antireflection layer using electron beam evaporation.

[0065] The solar cell described in this application is obtained through the above process.

[0066] In Example 2, unlike Example 1, the width of the projection area formed by the patterned second transparent conductive layer 34 on the first light-incident surface is 50 μm.

[0067] In Example 3, unlike Example 1, the patterned second transparent conductive layer 34 is made of indium zinc oxide (IZO) and has a thickness of 50 nm.

[0068] Example 4 differs from Example 1 in that the patterned second hole transport layer 33 is made of cuprous thiocyanate (CuSCN).

[0069] Comparative Example 1, such as Figure 5 As shown, unlike Embodiment 1, the composite layer 3 removes the second transparent conductive layer 34 and the second hole transport layer 33 in the dark area, retaining only the first transparent conductive layer 32 and the first hole transport layer 31 on the first surface. In this structure, the conductivity of a single transparent conductive layer for electrons is greater than that for holes, which cannot balance the recombination rate of electrons and holes. This results in a large number of unrecombined electrons at the interface between the first transparent conductive layer 32 and the first hole transport layer 31. Furthermore, in the dark area, since the lateral transport rate of holes is lower than that of electrons, the accumulation of electrons is more severe. Ultimately, the accumulation of charge in the composite layer leads to a lower fill factor (FF) and open-circuit voltage (Voc) in the tandem battery.

[0070] Comparative Example 2, such as Figure 6 As shown, unlike Example 1, the composite layer 3 includes a second transparent conductive layer 34, a metal layer 35, a first transparent conductive layer 32, and a first hole transport layer 31, which are stacked sequentially along the direction from the crystalline silicon bottom cell 4 to the perovskite top cell. The metal layer 35 is made of Au and has a thickness of 1 nm.

[0071] In this structure, holes from the perovskite top cell quickly reach the first transparent conductive layer 32 through the first hole transport layer 31, while electrons from the crystalline silicon bottom cell 4 quickly reach the metal layer 35 through the second transparent conductive layer 34. At this point, holes from the perovskite top cell and electrons from the crystalline silicon bottom cell 4 meet at the interface between the first transparent conductive layer 32 and the metal layer 35, resulting in electron-hole recombination. However, the strong reflectivity of the metal layer causes long-wavelength light transmitted through the perovskite top cell to be reflected away, preventing it from reaching the crystalline silicon bottom cell 4 for absorption. This results in a lower short-circuit current density (Jsc) for the solar cell.

[0072] The performance parameters of the embodiments and comparative examples are compared in Table 1 below: Table 1. Comparison of performance parameters between the examples and comparative examples. Energy conversion efficiency (Eff / %) Open circuit voltage Voc / V <![CDATA[Short-circuit current density Jsc / mA / cm 2 > Fill factor FF / % Example 1 34.29 1.990 20.64 83.50 Example 2 33.35 1.992 20.62 83.65 Example 3 34.37 1.997 20.63 83.45 Example 4 34.19 1.987 20.65 83.35 Comparative Example 1 33.99 1.983 20.62 83.15 Comparative Example 2 33.28 1.980 20.18 83.30 The IV test results of Examples 1, 2, 3, 4 and Comparative Examples 1, 2 show that the composite layer structure of the patterned second transparent conductive layer 34 and the second hole transport layer 33, as well as the entire first transparent conductive layer 32 and the first hole transport layer 31, can achieve rapid recombination of holes and electrons, improve the Voc and FF of the solar cell, and at the same time, without losing Jsc, ultimately making the solar cell have a higher energy conversion efficiency.

[0073] Based on the solar cells described in any of the above embodiments, this invention also provides a photovoltaic module, including a cell string, interconnecting components, and an encapsulation layer. The cell string is formed by electrically connecting a plurality of solar cells as described in any of the above embodiments; the interconnecting components are electrically connected to the solar cells; and the encapsulation layer covers the surface of the cell string. The encapsulation layer may include cover plates and back plates located on both sides of the cell string, as well as encapsulating films and other structures for encapsulation. Because this photovoltaic module uses the solar cells described in any of the above embodiments, it has the same beneficial effects as any of the above embodiments.

[0074] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A solar cell, characterized in that, include: Crystalline silicon bottom cells; A thin-film top cell has a first light-incident surface on the side away from the crystalline silicon bottom cell, and a plurality of parallel top electrodes are disposed on the first light-incident surface. A composite layer is located between the crystalline silicon bottom cell and the thin-film top cell, and the crystalline silicon bottom cell and the thin-film top cell are electrically connected through the composite layer; The composite layer includes a first transparent conductive layer and a first hole transport layer stacked together, and the first transparent conductive layer and the first hole transport layer are disposed on the entire surface of the solar cell. The composite layer further includes a patterned and stacked second transparent conductive layer and a second hole transport layer. The second transparent conductive layer has multiple spaced first projection areas on the first light-receiving surface. The second hole transport layer has multiple spaced second projection areas on the first light-receiving surface. The multiple parallel top electrodes have multiple spaced third projection areas on the first light-receiving surface. The extension direction of the first projection area is parallel to the extension direction of the top electrode. The extension direction of the second projection area is parallel to the extension direction of the top electrode. The first projection area and the second projection area overlap. Both the first projection area and the second projection area overlap with the third projection area.

2. The solar cell according to claim 1, characterized in that, The thin-film top cell is a perovskite top cell.

3. The solar cell according to claim 1 or 2, characterized in that, The ratio of the sum of the areas of the plurality of first projection regions to the sum of the areas of the plurality of second projection regions is 1.2:1 to 1:1.2; or, The sum of the areas of the first projection areas or the sum of the areas of the second projection areas accounts for 50% to 110% of the sum of the areas of the third projection areas.

4. The solar cell according to claim 1 or 2, characterized in that, The boundary of the first projection area or the boundary of the second projection area are respectively recessed and / or extended relative to the boundary of the third projection area, and the recessed and / or extended distance is 0% to 10% of the width of the top electrode.

5. The solar cell according to claim 1 or 2, characterized in that, The width of the first projection area or the second projection area is 20μm~60μm respectively.

6. The solar cell according to claim 1 or 2, characterized in that, The thickness of the first transparent conductive layer is 1nm~20nm; And / or, the thickness of the first hole transport layer is 1nm~5nm; And / or, the thickness of the second transparent conductive layer is 1nm~200nm, preferably 1nm~50nm; And / or, the thickness of the second hole transport layer is 1nm~200nm, preferably 1nm~50nm.

7. The solar cell according to claim 2, characterized in that, The first transparent conductive layer comprises one or more of indium tin oxide, indium zinc oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, boron-doped zinc oxide, indium gallium zinc oxide, and antimony-doped titanium dioxide; And / or, the second transparent conductive layer comprises one or more of indium tin oxide, indium zinc oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, boron-doped zinc oxide, indium gallium zinc oxide, and antimony-doped titanium dioxide.

8. The solar cell according to claim 2, characterized in that, The first hole transport layer includes 2PACz, MeO-4PACz, Me-4PACz, MeO-2PACz, MeO-6PACz, PTAA, and NiO. x One or more of CuSCN; And / or, the second hole transport layer includes 2PACz, MeO-4PACz, Me-4PACz, MeO-2PACz, MeO-6PACz, PTAA, NiO x One or more of CuSCN.

9. The solar cell according to claim 2, characterized in that, The second transparent conductive layer is in contact with the crystalline silicon bottom cell, the second hole transport layer is in contact with the first transparent conductive layer, the portion of the first transparent conductive layer outside the third projection area is in contact with the crystalline silicon bottom cell, and the first hole transport layer is in contact with the perovskite top cell. Alternatively, the second hole transport layer is in contact with the perovskite top cell, the second transparent conductive layer is in contact with the first hole transport layer, the portion of the first hole transport layer outside the third projection region is in contact with the perovskite top cell, and the first transparent conductive layer is in contact with the crystalline silicon bottom cell.

10. The solar cell according to claim 9, characterized in that, When the second transparent conductive layer is in contact with the crystalline silicon bottom cell, the first hole transport layer is a monomolecular self-assembled layer; and / or, when the second hole transport layer is in contact with the perovskite top cell, the second hole transport layer is a monomolecular self-assembled layer.

11. The solar cell according to claim 9, characterized in that, When the second transparent conductive layer is in contact with the crystalline silicon bottom cell, the first hole transport layer includes one or more of 2PACz, MeO-4PACz, Me-4PACz, MeO-2PACz, and MeO-6PACz; or, When the second hole transport layer is in contact with the perovskite top cell, the second hole transport layer includes one or more of 2PACz, MeO-4PACz, Me-4PACz, MeO-2PACz, and MeO-6PACz.

12. The solar cell according to any one of claims 1-11, characterized in that, The crystalline silicon bottom cell is one of the following: passivated emitter back cell, heterojunction cell, back contact cell, back contact heterojunction cell, and tunneling oxide passivated contact cell.

13. A photovoltaic module, characterized in that, include: A battery string, wherein the battery string is formed by electrically connecting a plurality of solar cells as described in any one of claims 1-12; Interconnector, electrically connected to the solar cell; And an encapsulation layer that covers the surface of the battery string.

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