A stacked battery, a method of manufacturing the same, and a photovoltaic module

Abstract

The application relates to the technical field of photovoltaic modules, in particular to a laminated cell, a preparation method thereof and a photovoltaic module. The laminated cell comprises a top cell unit, a bottom cell unit and a composite layer between the top cell unit and the bottom cell unit. The composite layer comprises a plurality of spaced rod bodies, the rod bodies extend along a first direction, and the rod bodies have a first doping element. The rod bodies at least have a first part and a second part which are stacked, and the doping concentration of the first part is different from that of the second part. The structure of the rod bodies which are spaced and extend along the first direction in the composite layer can form a vertical carrier transport channel in the composite layer, the diffusion path of the carriers is shortened, and thus the carrier transport rate is improved. Meanwhile, by adjusting the doping concentrations of the first part and the second part, the conduction band energy levels of the first part and the second part can be adjusted, so that the potential barrier of the carriers during transmission in the composite layer is reduced, and voltage loss is reduced.

Description

Technical Field

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

[0002] Photovoltaic modules convert solar energy into electrical energy, offering advantages such as being pollution-free, not geographically limited, and inexhaustible, making them a major direction for developing new energy sources. A photovoltaic module comprises multiple photovoltaic cells. Tandem cells, a type of photovoltaic cell, typically consist of three parts stacked sequentially: a top cell, a composite layer, and a bottom cell. The composite layer is used to transport charge carriers between the top and bottom cells. Summary of the Invention

[0003] This application provides a tandem battery, its fabrication method, and a photovoltaic module, which helps to solve the technical problem of poor carrier transport between the top and bottom battery units in the prior art.

[0004] In a first aspect, embodiments of this application provide a stacked battery, the stacked battery including a top battery unit, a bottom battery unit, and a composite layer located between the top battery unit and the bottom battery unit; the composite layer includes a plurality of spaced rods extending along a first direction, the rods having a first doping element; wherein, the rods have at least a first portion and a second portion stacked together, the doping concentration of the first portion being different from the doping concentration of the second portion.

[0005] In this embodiment, the composite layer includes multiple spaced rod structures extending along a first direction. This creates a vertical carrier transport channel within the composite layer, shortening the carrier diffusion path and thus improving the carrier transport rate. Simultaneously, the high specific surface area of ​​the rods provides more recombination sites for electrons and holes, enabling efficient recombination of holes generated by the top cell and electrons generated by the bottom cell within the composite layer, forming a continuous current path and avoiding voltage loss caused by charge accumulation. In summary, by incorporating rod structures extending along the first direction in the composite layer, the carrier transport path can be optimized and voltage loss reduced, thereby improving the carrier transport effect between the top and bottom cells and enhancing the photoelectric conversion efficiency of the tandem solar cell. Furthermore, the multiple spaced rod structures in the composite layer can scatter incident light multiple times upon its entry into the composite layer, extending the propagation path of the incident light and improving its absorption effect.

[0006] Meanwhile, by adjusting the doping concentration of the first and second parts, the conduction band energy levels of the first and second parts can be adjusted to reduce the potential barrier for carrier transport in the composite layer and reduce voltage loss.

[0007] In one specific embodiment, the doping concentration of the first portion is less than the doping concentration of the second portion.

[0008] In one specific embodiment, the ratio of the doping concentration D1 of the first part to the doping concentration D2 of the second part satisfies 0.2≤D1 / D2≤0.3.

[0009] In one specific embodiment, the length L1 of the first part satisfies 100nm≤L1≤300nm, and the length L2 of the second part satisfies 200nm≤L2≤500nm.

[0010] In one specific embodiment, the diameter φ1 of the rod satisfies 50nm≤φ1≤80nm.

[0011] In one specific embodiment, the conduction band of the first portion is 3.6eV-3.8eV, and the conduction band of the second portion is 4.2eV-4.4eV.

[0012] In one specific embodiment, along the first direction, the top cell includes a stacked electron transport layer, a perovskite layer, and a passivation transport layer; the material of the passivation transport layer includes in-situ polymerized thioacetamide.

[0013] In one specific embodiment, the composite layer further includes a first substrate connected to the second portion, the first substrate being located between the second portion and the bottom battery cell; the passivation transport layer further includes a second substrate and a connecting portion, the second substrate being disposed toward the top battery cell, and the connecting portion being located between adjacent rods.

[0014] In one specific embodiment, the thickness L3 of the first substrate satisfies 50nm≤L3≤100nm; and the thickness L4 of the second substrate satisfies 5nm≤L4≤10nm.

[0015] In one specific embodiment, along the first direction, the bottom battery cell includes a passivation contact layer, a silicon substrate, and a passivation layer stacked sequentially; wherein, along the first direction, the silicon substrate includes a first end and a second end disposed opposite to each other, the first end being connected to the passivation contact layer, and the second end being connected to the passivation layer; the first end has an inverted pyramid structure; and the second end has a regular pyramid structure.

[0016] In one specific embodiment, the height L5 of the inverted pyramid structure satisfies 1um≤L5≤3um, and the height L6 of the upright pyramid structure satisfies 200nm≤L6≤500nm.

[0017] Secondly, embodiments of this application also provide a method for preparing a stacked battery, the method comprising: Fabrication of bottom battery cells; A composite layer is prepared on top of the bottom battery cell; A top battery cell is fabricated on top of the composite layer; The composite layer includes a plurality of spaced rods, and along a first direction, the rods have at least a first part and a second part stacked together, wherein the doping concentration of the first part is different from that of the second part; the composite layer also includes a first substrate connected to the second part.

[0018] In one specific embodiment, when fabricating a composite layer on top of the bottom battery cell, the method for fabricating the stacked battery specifically includes: The first substrate was prepared by magnetron sputtering; The rod was prepared on the first substrate using a hydrothermal method.

[0019] In one specific embodiment, when the rod is fabricated on the first substrate using a hydrothermal method, the fabrication method of the stacked battery specifically includes: The first substrate is placed in a first growth solution, the first growth solution having a first doping element with a first preset doping concentration; the first growth solution is heated to a temperature of 80℃-100℃ for a time of 15min-60min to prepare the second part. The first substrate and the second part are placed in a second growth solution, the second growth solution having a first doping element with a second preset doping concentration; the second growth solution is heated to a temperature of 80℃-100℃ for a time of 30min-120min to prepare the first part; The first preset doping concentration is greater than the second preset doping concentration.

[0020] Thirdly, embodiments of this application also provide a photovoltaic module, the photovoltaic module including the tandem battery. Attached Figure Description

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

[0022] Figure 1 This is a schematic diagram of the structure of the stacked battery provided in this application in a specific embodiment; Figure 2 for Figure 1 A schematic diagram of the structure of a silicon substrate.

[0023] Figure label: 1-Stacked battery; 11-Top battery cell; 111-Perovskite layer; 112 - Electron transport layer; 113-Passivation transport layer; 113a - Second substrate; 113b - Connecting part; 114 - Conductive thin film layer; 12-bottom battery cell; 121 - Passivation contact layer; 122-Silicon substrate; 122a - First end; 122b - Second end; 122c - Inverted pyramid structure; 122d - Right Pyramid Structure; 123 - Passivation layer; 13-Composite layer; 131-rod body; 131a - Part 1; 131b - Part Two; 132-First basement; 14-Electrode. Detailed Implementation

[0024] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0025] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0026] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0027] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0028] Photovoltaic cells can convert solar energy into electrical energy, offering advantages such as being pollution-free, not geographically limited, and inexhaustible, making them a major direction for developing new energy sources. A photovoltaic module comprises multiple photovoltaic cells. Tandem cells, a type of photovoltaic cell, typically consist of three parts stacked sequentially: a top cell, a composite layer, and a bottom cell. The composite layer facilitates carrier transport between the top and bottom cells. Indium tin oxide (ITO) thin films are commonly used as the composite layer, but ITO thin films have relatively poor carrier transport performance.

[0029] To solve the above technical problems, such as Figure 1 As shown, this application embodiment provides a stacked battery 1, including a top battery unit 11, a bottom battery unit 12, and a composite layer 13 located between the top battery unit 11 and the bottom battery unit 12. The composite layer 13 includes a plurality of spaced rods 131 extending along a first direction Z.

[0030] This design incorporates multiple spaced rod-shaped structures 131 extending along the first direction Z within the composite layer 13. This creates a vertical carrier transport channel within the composite layer 13, shortening the carrier diffusion path and thus improving the carrier transport rate. Simultaneously, the high specific surface area of ​​the rod-shaped structures 131 provides more recombination sites for electrons and holes, enabling efficient recombination of holes generated by the top cell unit 11 and electrons generated by the bottom cell unit 12 within the composite layer 13. This forms a continuous current path, preventing voltage loss due to charge accumulation. In summary, by incorporating rod-shaped structures 131 extending along the first direction Z within the composite layer 13, the carrier transport path can be optimized, and voltage loss reduced, thereby improving the carrier transport efficiency between the top cell unit 11 and the bottom cell unit 12 and ultimately enhancing the photoelectric conversion efficiency of the tandem solar cell 1. In addition, the multiple spaced rods 131 in the composite layer 13 can scatter the incident light multiple times when it enters the composite layer 13, thus extending the propagation path of the incident light and improving the absorption effect of the incident light.

[0031] In the above embodiments, the rod 131 may also have a first doping element, and the rod 131 has at least a first part 131a and a second part 131b stacked together, wherein the doping concentration of the first part 131a is different from the doping concentration of the second part 131b.

[0032] By adjusting the doping concentration of the first part 131a and the second part 131b, the conduction band energy levels of the first part 131a and the second part 131b can be adjusted to reduce the potential barrier for carrier transport in the composite layer 13 and reduce voltage loss.

[0033] Specifically, the top cell unit 11 can be a perovskite cell, and the bottom cell unit 12 can be a TOPCon cell. When the tandem cell 1 is operating, holes generated in the top cell unit 11 are transported towards the bottom cell unit 12, and electrons generated in the bottom cell unit 12 are transported towards the top cell unit 11. Holes and electrons efficiently recombine within the composite layer 13, forming a continuous current path. This results in a lower doping concentration in the first part 131a and a higher doping concentration in the second part 131b, thus making the conduction band value of the first part 131a smaller than that of the second part 131b. When holes in the top cell unit 11 are transported towards the bottom cell unit 12, the direction of hole transport changes from the first part 131a towards the second part 131b, ensuring that the hole transport trend follows a migration from a low conduction band to a high conduction band. This reduces the potential barrier for holes flowing through the composite layer 13, increases the hole transport rate, and reduces voltage loss. Simultaneously, when electrons in the bottom cell 12 are transported towards the top cell 11, the direction of electron transport changes from the second part 131b towards the first part 131a. This ensures that the electron transport trend conforms to migration from the high conduction band to the low conduction band, thereby reducing the potential barrier for electrons flowing in the composite layer 13, increasing the electron transport rate, and reducing voltage loss. In summary, by adjusting the doping concentration of the first part 131a and the second part 131b of the rod 131, the conduction band values ​​of the first part 131a and the second part 131b can be adjusted, thereby improving the efficient bidirectional transport of charge carriers in the composite layer 13 and reducing voltage loss during the transport process.

[0034] In this embodiment of the application, the doping concentration of the first doped element in the first part 131a and the second part 131b of the rod 131 can be measured by ECV (electrochemical capacitance-voltage method). Specifically, three or more points are selected for doping concentration measurement in the first part 131a and the second part 131b of the rod 131, and the average value is taken to obtain the specific doping concentration values ​​of the first part 131a and the second part 131b, respectively.

[0035] In the above embodiments, the rod structure in the composite layer 13 can be zinc oxide material, and the first doping element can be aluminum element, thereby providing free electrons to improve the conductivity of the composite layer 13 and also improve the optical transparency of the composite layer 13.

[0036] In this embodiment, the first direction Z can be the thickness direction of the stacked battery 1.

[0037] In the above embodiments, the conduction band of the first portion 131a can be 3.6eV-3.8eV, for example, the conduction band of the first portion 131a can specifically be 3.6eV, 3.65eV, 3.7eV, 3.75eV, 3.8eV, etc. Simultaneously, the conduction band of the second portion 131b can be 4.2eV-4.4eV, for example, the conduction band of the second portion 131b can specifically be 4.2eV, 4.25eV, 4.3eV, 4.35eV, 4.4eV, etc., so that the conduction band value of the first portion 131a is smaller than the conduction band value of the second portion 131b. This reduces the potential barrier when holes in the top battery cell 11 propagate towards the bottom battery cell 12, increases the hole propagation rate, and reduces voltage loss during hole propagation. Simultaneously, it also reduces the potential barrier when electrons in the bottom battery cell 12 propagate towards the top battery cell 11, increases the electron propagation rate, and reduces voltage loss during electron propagation.

[0038] In other embodiments, the conductors of the first part 131a and the second part 131b may also be other specific values, which can be adaptively adjusted according to the actual situation.

[0039] In the above embodiments, the ratio of the doping concentration D1 of the first part 131a to the doping concentration D2 of the second part 131b satisfies 0.2≤D1 / D2≤0.3. By limiting the ratio of the doping concentration of the first part 131a to the doping concentration of the second part 131b, the conduction band values ​​of the first part 131a and the second part 131b are adjusted to improve the carrier transport effect in the composite layer 13 and enhance the working efficiency of the tandem cell 1.

[0040] In other embodiments, the doping concentration ratio of the first part 131a and the second part 131b can also be other values, which can be adaptively adjusted according to the actual situation.

[0041] In another embodiment, the rod may further include a third portion (not shown in the figure) located between the first portion and the second portion, and the doping concentration of the third portion is adjusted to be greater than the doping concentration of the first portion and less than the doping concentration of the second portion, so that the conduction band of the third portion is greater than the conduction band value of the first portion and less than the conduction band value of the second portion, thereby reducing the conduction band value difference between the first portion, the third portion and the second portion, thereby reducing the potential barrier value when charge carriers flow between the first portion, the third portion and the second portion, and reducing voltage loss.

[0042] In other embodiments, the doping concentration of the first doped element in the rod 131 can also be gradually varied along the first direction Z. For example, along the direction from the top battery cell 11 to the bottom battery cell 12, the doping concentration of the first doped element in the rod 131 gradually increases, thereby further reducing the potential barrier when the charge carriers flow in the composite layer 13, significantly improving the charge carrier transport rate and reducing voltage loss.

[0043] In one specific embodiment, such as Figure 1 As shown, the diameter φ1 of the rod 131 satisfies 50nm≤φ1≤80nm. For example, the diameter φ1 of the rod 131 can be 50nm, 60nm, 70nm, 80nm, etc. By limiting the diameter of the rod 131, the specific surface area of ​​the rod 131 and the resistance to carrier migration can be balanced, the increase of interface defects can be avoided, and the effective contact area can be increased, thereby improving the carrier transport efficiency of the rod 131.

[0044] In addition, in other embodiments, the diameter of the rod 131 can be other values, which can be adaptively adjusted according to the actual situation.

[0045] In the above embodiments, the length L1 of the first part 131a satisfies 100nm ≤ L1 ≤ 300nm. For example, the length L1 of the first part 131a can be 100nm, 150nm, 200nm, 250nm, 300nm, etc., making the length of the first part 131a shorter, which can reduce the absorption of long-wavelength light by the rod 131 and ensure the absorption and utilization of short-wavelength light by the top battery unit 11. At the same time, the length L2 of the second part 131b satisfies 200nm ≤ L2 ≤ 500nm. For example, the length L2 of the second part 131b can be 200nm, 300nm, 400nm, 450nm, 500nm, etc., making the length of the second part 131b longer, which can optimize light scattering, allowing more long-wavelength light to reach the bottom battery unit 12, improving the utilization rate of low-energy photons by the bottom battery unit 12, and reducing spectral waste.

[0046] Furthermore, in other embodiments, the lengths of the first portion 131a and the second portion 131b can also be other specific values, which can be adaptively adjusted according to actual conditions. The lengths of the first portion 131a and the second portion 131b can be the same or different.

[0047] The following descriptions will use the top cell unit 11 as a perovskite cell and the bottom cell unit 12 as an example of a TOPCon cell.

[0048] In one specific embodiment, such as Figure 1As shown, along the first direction Z, the top battery cell 11 includes a stacked conductive thin film layer 114, an electron transport layer 112, a perovskite layer 111, and a passivation transport layer 113. The passivation transport layer 113 is made of in-situ polymerized thioacetamide.

[0049] Through this design, the sulfur atoms in the in-situ polymerized thioacetamide in the passivation transport layer 113 have strong coordination ability, enabling them to coordinate with lead ions on the surface of the perovskite layer 111 to form Pb-S bonds. This passivates the surface of the perovskite layer 111, reducing recombination losses. Simultaneously, the in-situ polymerized thioacetamide also possesses hole transport properties, preferentially extracting holes and transporting them towards the bottom cell unit 12, while blocking electron backflow and reducing charge recombination.

[0050] Furthermore, by positioning the passivation transport layer 113 between the perovskite layer 111 and the composite layer 13, the passivation transport layer 113 also provides passivation and protection for the composite layer 13. Compared to the hole transport layer placed between the perovskite layer and the composite layer in related technologies, this embodiment, by providing a passivation transport layer 113 comprising in-situ polymerized thioacetamide, not only functions as a hole transport layer but also simultaneously provides passivation and protection for both the perovskite layer 111 and the composite layer 13.

[0051] In the above embodiments, the composite layer 13 further includes a first substrate 132 connected to the second portion 131b, the first substrate 132 being located between the second portion 131b and the bottom battery cell 12. The passivation transport layer 113 further includes a second substrate 113a and a connecting portion 113b, the second substrate 113a being disposed toward the top battery cell 11, and the connecting portion 113b being located between adjacent rods 131.

[0052] This design allows the passivation transport layer 113 to have a second substrate 113a and a connecting portion 113b, with the connecting portion 113b positioned between adjacent rod 131 structures of the composite layer 13. This further increases the contact area between the passivation transport layer 113 and the rod 131, thereby enhancing the passivation effect of the passivation transport layer 113 on the rod 131. Simultaneously, it also increases the coverage area of ​​the passivation transport layer 113 on the rod 131, thus improving the protective effect of the passivation transport layer 113 on the rod 131.

[0053] In the above embodiments, the thickness L3 of the first substrate 132 satisfies 50nm ≤ L3 ≤ 100nm. For example, the thickness L3 of the first substrate 132 can specifically be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc. By limiting the thickness of the first substrate 132, the structural strength of the first substrate 132 can be improved, preventing interface cracking or peeling, and simultaneously improving the connection strength between the rod and the first substrate. Meanwhile, the thickness L4 of the second substrate 113a satisfies 5nm ≤ L4 ≤ 10nm. For example, the thickness L4 of the second substrate 113a can specifically be 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, etc. By limiting the thickness of the second substrate 113a, the passivation effect of the passivation transport layer 113 on the perovskite layer 111 can be improved, thereby increasing the photoelectric conversion efficiency of the top cell unit 11.

[0054] In addition, in other embodiments, the thicknesses of the first substrate 132 and the second substrate 113a can be other specific values, which can be adaptively adjusted according to the actual situation.

[0055] In one specific embodiment, such as Figure 1 and Figure 2 As shown, along the first direction Z, the bottom battery cell 12 may include a passivation contact layer 121, a silicon substrate 122, and a passivation layer 123 stacked sequentially. The silicon substrate 122 may include a first end 122a and a second end 122b disposed opposite each other along the first direction Z. The first end 122a is connected to the passivation contact layer 121, and the second end 122b is connected to the passivation layer 123. The first end 122a has an inverted pyramid structure 122c, and the second end 122b has a regular pyramid structure 122d.

[0056] In this embodiment, the first end 122a of the silicon substrate 122, facing the top battery cell 11, is the light-receiving surface of the bottom battery cell 12. The first end 122a of the silicon substrate 122 is provided with an inverted pyramid structure 122c, which allows the light-receiving surface of the bottom battery cell 12 to have a larger surface area and a more complex incident path, increasing the number of reflections of incident light, thereby reducing reflection loss and improving the absorption effect of incident light. The second end 122b of the silicon substrate 122, facing away from the top battery cell 11, is the backlight surface of the bottom battery cell 12. The second end 122b of the silicon substrate 122 is provided with a positive pyramid structure 122d, which can improve the absorption effect of reflected light and increase the bifaciality of the bottom battery cell 12.

[0057] The passivation contact layer 121 on the front side of the silicon substrate 122 includes a passivation contact structure composed of a tunneling oxide layer and a doped polycrystalline silicon layer, thereby reducing recombination losses. The passivation layer 123 on the back side of the silicon substrate 122 can be an aluminum oxide layer and / or a silicon nitride layer, which serves to passivate and protect the bottom cell 12.

[0058] In the above embodiments, the height L5 of the inverted pyramid structure 122c satisfies 1µm ≤ L5 ≤ 3µm. For example, the height L5 of the inverted pyramid structure 122c can be 1µm, 1.5µm, 2µm, 2.5µm, 3µm, etc., making the height of the inverted pyramid structure 122c on the light-receiving surface of the bottom battery unit 12 relatively high, which can increase the number of reflections of incident light and make the light-trapping effect of long-wavelength light more obvious. At the same time, the height L6 of the upright pyramid structure 122d satisfies 200nm ≤ L6 ≤ 500nm. For example, the height L6 of the upright pyramid structure can be 200nm, 300nm, 400nm, 450nm, 500nm, etc., making the height of the upright pyramid structure 122d on the back light surface of the bottom battery unit 12 relatively small, which can reduce the optical scattering of the back light surface of the bottom battery unit 12 and enhance the utilization rate of long-wavelength light transmitted to the back light surface. It can also reduce the influence of the inverted pyramid structure 122c on the passivation contact layer 121, ensure the passivation effect, and reduce parasitic absorption. Meanwhile, the silicon substrate 122 has a differentiated pyramid structure design for its light-receiving and back-light-receiving surfaces. By optimizing for different lighting conditions on the light-receiving and back-light-receiving surfaces, the light absorption efficiency can be significantly improved.

[0059] In other embodiments, the heights of the inverted pyramid structure 122c and the upright pyramid structure 122d can be other values, which can be adaptively adjusted according to the actual situation.

[0060] In the above embodiments, as Figure 1 As shown, electrodes 14 are also provided on the top battery unit 11 and the bottom battery unit 12 respectively.

[0061] This application also provides a method for preparing the above-mentioned stacked battery 1, including: S11: Fabrication of bottom battery cell 12; S12: A composite layer 13 is prepared on top of the bottom battery cell 12; S13: A top cell unit 11 is fabricated on top of the composite layer 13.

[0062] The composite layer 13 includes a plurality of spaced rods 131. Along the first direction Z, each rod 131 has at least a first portion 131a and a second portion 131b stacked together. The doping concentration of the first portion 131a is different from that of the second portion 131b. The composite layer 13 also includes a first substrate 132 connected to the second portion 131b.

[0063] In this embodiment, by setting a rod structure 131 in the composite layer 13, and making the rod structure 131 have at least a first part 131a and a second part 131b with different doping concentrations, the carrier transport effect between the top cell unit 11 and the bottom cell unit 12 can be significantly optimized, the voltage loss during the transport process can be reduced, and the overall working efficiency of the stacked cell 1 can be improved.

[0064] In some embodiments, step S12 specifically includes: S121: Measurement and control sputtering to prepare the first substrate 132; S122: The rod 131 is prepared on the first substrate 132 by hydrothermal method.

[0065] In this embodiment, when fabricating the composite layer 13 on the bottom battery cell 12, a first substrate 132 is first prepared by measurement and control sputtering. This allows for the fabrication of a rod 131 on the first substrate 132, improving the structural stability of the rod 131 and enhancing the connection between the composite layer 13 and the bottom battery cell 12. Furthermore, the hydrothermal method for fabricating the rod 131 offers advantages such as low energy consumption, ease of control, and low defect density, thereby improving the fabrication quality of the rod 131.

[0066] In some embodiments, step S122 specifically includes: S122a: Place the first substrate 132 in the first growth solution, the first growth solution having a first doping element with a first preset doping concentration; heat the first growth solution at a temperature of 80℃-100℃ for a time of 15min-60min to prepare the second part 131b. S122b: The first substrate 132 and the second part 131b are placed in the second growth solution, the second growth solution having a first dopant element with a second preset doping concentration; the second growth solution is heated to a temperature of 80℃-100℃ for a time of 30min-120min to prepare the first part.

[0067] The first preset doping concentration is greater than the second preset doping concentration.

[0068] In this embodiment, when the second part 131b is prepared on the first substrate 132 using a hydrothermal method, the first preset doping concentration of the first dopant element in the first growth solution is made relatively high, thereby giving the prepared second part 131b a relatively high doping concentration. When the first part 131a is further prepared on the second part 131b using a hydrothermal method, the second preset doping concentration of the first dopant element in the second growth solution is made relatively low, thereby giving the prepared first part 131a a relatively low doping concentration. This allows the conduction band values ​​of the first part 131a and the second part 131b to be set to meet the different carrier transport characteristics, thereby improving the carrier transport effect between the top cell unit and the bottom cell unit, reducing voltage loss, and improving the working efficiency of the tandem cell 1.

[0069] The first preset doping concentration can be 2 mol%, and the second preset doping concentration can be 0.5 mol%, so that the doping concentration of the first part 131a and the doping concentration of the second part 131b meet the usage requirements. In other embodiments, the first and second preset doping concentrations can also be other values, which can be adaptively adjusted according to actual conditions.

[0070] In the above embodiments, when preparing the first part 131a and the second part 131b, the first growth solution and the second growth solution may contain aluminum nitrate, so that the prepared first part 131a and the second part 131b contain a first dopant element. The preparation temperature can be 80℃-100℃, the preparation time of the second part 131b can be 30min-120min, and the preparation time of the first part 131a can be 15min-60min. During the preparation process, the specific lengths of the first part 131a and the second part 131b can be adjusted by controlling the preparation time.

[0071] In the above embodiments, when preparing the bottom battery cell 12, step S11 may include, but is not limited to, the following steps: S111: Fabrication of silicon substrate 122; S112: An inverted pyramid structure 122c is fabricated on the light-receiving surface of the silicon substrate 122, and a positive pyramid structure 122d is fabricated on the back-light-receiving surface of the silicon substrate 122. S113: Deposit a passivation layer 123 on the back surface of the silicon substrate 122; S114: Deposit a passivation contact layer 121 on the light-receiving surface of the silicon substrate 122.

[0072] In this embodiment, the silicon substrate 122 has a differentiated pyramid structure design for its light-receiving and back-light-receiving surfaces. By optimizing for different lighting conditions on the light-receiving and back-light-receiving surfaces, the light absorption efficiency can be significantly improved. During the fabrication process, the light-receiving surface can be etched using a potassium hydroxide solution, and the back-light-receiving surface can be etched using a sodium silicate solution.

[0073] In the above embodiments, when fabricating the top battery cell 11, step S13 may include, but is not limited to, the following steps: S131: A passivation transport layer 113 is prepared on the composite layer 13 using a thermal evaporation process; S132: Deposit a perovskite layer 111 on the passivation transport layer 113; S133: Electron transport layer 112 is prepared by vacuum evaporation on the perovskite layer; S134: A conductive thin film layer 114 is prepared by sputtering on the electron transport layer 112.

[0074] In this embodiment, the passivation transport layer 113 is prepared by thermal evaporation, which has the advantages of low cost and easy control, thereby improving the preparation quality of the passivation transport layer 113.

[0075] This application embodiment also provides a photovoltaic module, including the above-mentioned tandem cell 1. By setting a composite layer 13 with different doping concentration regions, the carrier transport between the top cell unit 11 and the bottom cell unit 12 in the tandem cell 1 is optimized, voltage loss is reduced, and the working efficiency of the tandem cell 1 is improved, thereby improving the overall working efficiency of the photovoltaic module.

[0076] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A stacked battery, characterized in that, The stacked battery includes a top battery unit, a bottom battery unit, and a composite layer located between the top battery unit and the bottom battery unit; The composite layer includes a plurality of spaced rods that extend along a first direction and have a first doping element. The rod body has at least a first part and a second part stacked together, wherein the doping concentration of the first part is different from that of the second part.

2. The stacked battery according to claim 1, characterized in that, The doping concentration of the first part is less than that of the second part.

3. The stacked battery according to claim 2, characterized in that, The ratio of the doping concentration D1 of the first part to the doping concentration D2 of the second part satisfies 0.2≤D1 / D2≤0.

3.

4. The stacked battery according to any one of claims 1-3, characterized in that, The length L1 of the first part satisfies 100nm≤L1≤300nm, and the length L2 of the second part satisfies 200nm≤L2≤500nm.

5. The stacked battery according to any one of claims 1-3, characterized in that, The diameter φ1 of the rod satisfies 50nm≤φ1≤80nm.

6. The stacked battery according to any one of claims 1-3, characterized in that, The conduction band of the first part is 3.6eV-3.8eV, and the conduction band of the second part is 4.2eV-4.4eV.

7. The stacked battery according to claim 2, characterized in that, Along the first direction, the top battery cell includes an electron transport layer, a perovskite layer, and a passivation transport layer stacked together; The material of the passivation transport layer includes in-situ polymerized thioacetamide.

8. The stacked battery according to claim 7, characterized in that, The composite layer further includes a first substrate connected to the second portion, the first substrate being located between the second portion and the bottom battery cell; The passivation transport layer further includes a second substrate and a connecting portion, the second substrate being disposed toward the top battery cell, and the connecting portion being located between adjacent rods.

9. The stacked battery according to claim 8, characterized in that, The thickness L3 of the first substrate satisfies 50nm≤L3≤100nm; the thickness L4 of the second substrate satisfies 5nm≤L4≤10nm.

10. The stacked battery according to claim 1, characterized in that, Along the first direction, the bottom battery cell includes a passivation contact layer, a silicon substrate, and a passivation layer stacked sequentially. Along the first direction, the silicon substrate includes a first end and a second end disposed opposite to each other, the first end being connected to the passivation contact layer, and the second end being connected to the passivation layer; the first end has an inverted pyramid structure; and the second end has an upright pyramid structure.

11. The stacked battery according to claim 10, characterized in that, The height L5 of the inverted pyramid structure satisfies 1um≤L5≤3um, and the height L6 of the upright pyramid structure satisfies 200nm≤L6≤500nm.

12. A method for preparing a stacked battery, characterized in that, The method for preparing the stacked battery includes: Fabrication of bottom battery cells; A composite layer is prepared on top of the bottom battery cell; A top battery cell is fabricated on top of the composite layer; The composite layer includes a plurality of spaced rods, and along a first direction, the rods have at least a first part and a second part stacked together, wherein the doping concentration of the first part is different from that of the second part; the composite layer also includes a first substrate connected to the second part.

13. The method for preparing a stacked battery according to claim 12, characterized in that, When fabricating a composite layer on top of the bottom battery cell, the method for fabricating the stacked battery specifically includes: The first substrate was prepared by magnetron sputtering; The rod was prepared on the first substrate using a hydrothermal method.

14. The method for preparing a stacked battery according to claim 13, characterized in that, When the rod is prepared on the first substrate using a hydrothermal method, the preparation method of the stacked battery specifically includes: The first substrate is placed in a first growth solution, the first growth solution having a first doping element with a first preset doping concentration; the first growth solution is heated to a temperature of 80℃-100℃ for a time of 15min-60min to prepare the second part. The first substrate and the second part are placed in a second growth solution, the second growth solution having a first doping element with a second preset doping concentration; the second growth solution is heated to a temperature of 80℃-100℃ for a time of 30min-120min to prepare the first part; The first preset doping concentration is greater than the second preset doping concentration.

15. A photovoltaic module, characterized in that, The photovoltaic module includes the tandem cell as described in any one of claims 1-11.

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