Solar cell and preparation method therefor, and photovoltaic module

Abstract

Provided in the present application are a solar cell and a preparation method therefor, and a photovoltaic module. The solar cell comprises a bottom cell, a composite layer and a top cell, wherein the composite layer is located between the bottom cell and the top cell; a light-receiving surface of the bottom cell is provided with an N-type doped layer; and a non-light-receiving surface of the top cell is provided with a hole transport layer. The composite layer comprises a first composite sub-layer and a second composite sub-layer that are stacked, wherein the surface of the first composite sub-layer facing away from the second composite sub-layer faces the N-type doped layer; the surface of the second composite sub-layer facing away from the first composite sub-layer faces the hole transport layer; the carrier concentration of the first composite sub-layer is greater than the carrier concentration of the second composite sub-layer; and the resistivity of the first composite sub-layer and / or the resistivity of the second composite sub-layer are / is from 6.5×10-4 Ω·cm to 1.6×10-2 Ω·cm. The technical solution increases the open-circuit voltage and the filling factor of a solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

Description

A solar cell and its fabrication method, and a photovoltaic module

[0001] This application claims priority to Chinese Patent Application No. 202510099754.5, filed with the Chinese Patent Office on January 22, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of solar cells, and more particularly to a solar cell and its preparation method, and a photovoltaic module. Background Technology

[0003] Stacked solar cells can further improve the utilization of the solar spectrum, thereby improving the photoelectric conversion efficiency of solar cells.

[0004] In tandem solar cells, the composite layer plays a crucial role in the photoelectric conversion efficiency of the solar cell device. Improving the performance of the composite layer to enhance the photoelectric conversion efficiency of the tandem solar cell has become a pressing technical problem to be solved. Summary of the Invention

[0005] To address the aforementioned technical problems, this application discloses a solar cell and its fabrication method, as well as a photovoltaic module, to improve the performance of the composite layer and thereby enhance the photoelectric conversion efficiency of the tandem solar cell.

[0006] In one aspect, this application provides a solar cell, including a bottom cell, a composite layer, and a top cell, wherein the composite layer is located between the bottom cell and the top cell, the light-receiving surface of the bottom cell has an N-type doped layer, and the back-lighting surface of the top cell has a hole transport layer, wherein...

[0007] The composite layer includes a first composite sublayer and a second composite sublayer stacked together. The side of the first composite sublayer facing away from the second composite sublayer faces the N-type doped layer, and the side of the second composite sublayer facing away from the first composite sublayer faces the hole transport layer.

[0008] The carrier concentration of the first composite sublayer is greater than that of the second composite sublayer;

[0009] The resistivity of the first composite sublayer and / or the resistivity of the second composite sublayer is 6.5 × 10⁻⁶. -4 Ω·cm~1.6×10 -2 Ω·cm.

[0010] In some embodiments of this application, the carrier concentration of the first composite sublayer is C1, and the carrier concentration of the second composite sublayer is C2, 7.0 × 10⁻⁶. 20 pcs / cm 3 ≤C1≤1.0×1021 pcs / cm 3 1.0×10 19 pcs / cm 3 ≤C2≤2.5×10 20 pcs / cm 3 .

[0011] In some embodiments of this application, the carrier mobility of the first composite sublayer is CM1, and the carrier mobility of the second composite sublayer is CM2, where CM1 < CM2.

[0012] In some embodiments of this application, 1cm 2 / V·s≤CM1≤13cm 2 / V·s, 30cm 2 / V·s≤CM2≤40cm 2 / V·s.

[0013] In some embodiments of this application, the resistivity of the first composite sublayer is R1, 6.5 × 10⁻⁶. -4 Ω·cm≤R1≤6.5×10 -3 Ω·cm, the resistivity of the second composite sublayer is R2, 8.0 × 10⁻⁶. -4 Ω·cm≤R2≤1.6×10 -2 Ω·cm.

[0014] In some embodiments of this application, the work function of the first composite sublayer is 3.4 eV to 3.8 eV, and the work function of the second composite sublayer is 4.3 eV to 5.0 eV.

[0015] In some embodiments of this application, the thickness of the first composite sublayer is H1, the thickness of the second composite sublayer is H2, and 0nm≤H2-H1≤14nm.

[0016] In some embodiments of this application, 1nm≤H1≤5nm, 3nm≤H2≤15nm.

[0017] In some embodiments of this application, the materials of the first composite sublayer and / or the second composite sublayer include at least one of indium zinc oxide, indium tin oxide, zinc aluminum oxide, tungsten-doped indium oxide, and cerium-doped indium oxide.

[0018] In some embodiments of this application, the bottom cell includes a silicon substrate, wherein a first intrinsic amorphous silicon layer and an N-type doped layer are sequentially stacked on the light-receiving surface of the silicon substrate, and a second intrinsic amorphous silicon layer, a P-type doped layer, and a second transparent electrode layer are sequentially stacked on the back-light-receiving surface of the silicon substrate.

[0019] In some embodiments of this application, a hole modification layer, a perovskite layer, a passivation layer, an electron transport layer, a buffer layer, a first transparent electrode layer, and an antireflection layer are stacked sequentially on the hole transport layer.

[0020] Secondly, this application provides a method for fabricating a solar cell as described in the first aspect, comprising the following steps:

[0021] A bottom cell is provided, and a first composite sublayer and a second composite sublayer are sequentially prepared on the surface of the N-type doped layer of the bottom cell by magnetron sputtering to form a composite layer, wherein the oxygen flow rate introduced to prepare the second composite sublayer is greater than the oxygen flow rate introduced to prepare the first composite sublayer.

[0022] Other functional layers are sequentially prepared on the surface of the composite layer, and the other functional layers include at least a hole transport layer, a hole modification layer, and a perovskite layer.

[0023] In some embodiments of this application, the oxygen flow rate introduced to prepare the first composite sublayer is F1, where 0 Sccm ≤ F1 ≤ 6 Sccm, and the oxygen flow rate introduced to prepare the second composite sublayer is F2, where 20 Sccm ≤ F2 - F1 ≤ 50 Sccm.

[0024] In some embodiments of this application, the sputtering pressure of the magnetron sputtering method is 0.3 Pa to 1.0 Pa, the temperature is 23 °C to 200 °C, the flow rate of argon gas is 500 Sccm to 1200 Sccm, and the sputtering power of the target material is 100 W to 2000 W.

[0025] And / or, the coating transfer rate of the first composite sublayer is 4.1 mm / s to 495.0 mm / s, and the coating transfer rate of the second composite sublayer is 1.4 mm / s to 165.0 mm / s.

[0026] In some embodiments of this application, the preparation method further includes:

[0027] An electron transport layer, a buffer layer, a first transparent electrode layer, and an antireflection layer are sequentially fabricated on the surface of the passivation layer.

[0028] Thirdly, this application provides a photovoltaic module, which includes a solar cell as described in the first aspect, or the photovoltaic module includes a solar cell prepared by the preparation method described in the second aspect.

[0029] Compared with the prior art, this application has at least the following beneficial effects:

[0030] The solar cell and its fabrication method, as well as the photovoltaic module provided in this application, wherein the composite layer of the solar cell includes a first composite sublayer and a second composite sublayer stacked together, and the resistivity of the first composite sublayer and / or the resistivity of the second composite sublayer is 6.5 × 10⁻⁶. -4 Ω·cm~1.6×10 -2 The resistivity of the first composite sublayer is greater than that of the second composite sublayer, and the resistivity of the first composite sublayer and / or the second composite sublayer is adjusted within the range of this application. This allows the first and second composite sublayers to have suitable resistivity, which on the one hand suppresses the lateral charge transport at the interface between the first composite sublayer and the bottom cell, and on the other hand suppresses the lateral charge transport at the interface between the second composite sublayer and the top cell. Furthermore, based on the aforementioned resistivity range, by adjusting the carrier concentration of the first composite sublayer to be greater than that of the second composite sublayer, the Fermi level of the first composite sublayer is shifted upward, achieving energy level matching between the first composite sublayer and the N-type doped layer, reducing the contact barrier between the interface of the first composite sublayer and the N-type doped layer, and promoting the transport of electrons from the bottom cell to the composite layer. On the other hand, the Fermi level of the second composite sublayer is shifted downward, achieving energy level matching between the second composite sublayer and the hole transport layer, reducing the interface contact barrier between the second composite sublayer and the hole transport layer, and promoting the transport of holes from the top cell to the composite layer. In summary, the composite layer of this application has a bilayer structure, which simultaneously achieves contact energy level matching between the composite layer and the N-type doped layer of the bottom cell and the hole transport layer of the top cell. It also suppresses the lateral transport of charge on the surface of the composite layer, promotes the transport of charge at the interface, reduces open-circuit voltage loss, and improves the open-circuit voltage and fill factor of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in 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.

[0032] Figure 1 is a schematic diagram of the structure of a solar cell in one embodiment of this application.

[0033] Explanation of reference numerals in the attached figures: 1. Bottom cell; 2. Composite layer; 3. Top cell; 4. Positive electrode; 5. Back electrode; 11. N-type doped layer; 12. First intrinsic amorphous silicon layer; 13. Silicon substrate; 14. Second intrinsic amorphous silicon layer; 15. P-type doped layer; 16. Second transparent electrode layer; 21. First composite sublayer; 22. Second composite sublayer; 31. Hole transport layer; 32. Hole modification layer; 33. Perovskite layer; 34. Passivation layer; 35. Electron transport layer; 36. Buffer layer; 37. First transparent electrode layer; 38. Antireflection layer. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0036] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0037] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; 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, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0038] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0039] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0040] Currently, the composite layer contacts the N-type doped layer of the bottom cell on one side and the hole transport layer of the top cell on the other, requiring simultaneous good contact at both interfaces. A single-layer composite layer struggles to achieve energy level matching with both the N-type doped layer and the hole transport layer, resulting in a high contact barrier that hinders electron transport between the bottom and top cells, leading to charge accumulation and open-circuit voltage loss. Furthermore, to balance the contact performance at both interfaces, the single-layer composite layer needs low surface resistance. This low surface resistance allows for lateral charge transport across the composite layer surface, causing current shunting in the solar cell and further reducing its open-circuit voltage.

[0041] In view of this, firstly, this application provides a solar cell. Figure 1 is a schematic diagram of the structure of a solar cell according to one embodiment of this application. Referring to Figure 1, the solar cell includes a bottom cell 1, a composite layer 2, and a top cell 3. The composite layer 2 is located between the bottom cell 1 and the top cell 3. The light-receiving surface of the bottom cell 1 has an N-type doped layer 11, and the back-lighting surface of the top cell 3 has a hole transport layer 31. The composite layer 2 includes a first composite sublayer 21 and a second composite sublayer 22 stacked together. The side of the first composite sublayer 21 facing away from the second composite sublayer 22 faces the N-type doped layer 11, and the side of the second composite sublayer 22 facing away from the first composite sublayer 21 faces the hole transport layer 31. The carrier concentration of the first composite sublayer 21 is greater than that of the second composite sublayer 22. The resistivity of the first composite sublayer 21 and / or the resistivity of the second composite sublayer 22 is 6.5 × 10⁻⁶. -4 Ω·cm~1.6×10 -2 Ω·cm.

[0042] In this application, by adjusting the resistivity of the first composite sublayer and / or the resistivity of the second composite sublayer within the range of this application, the first and second composite sublayers are made to have suitable resistivity. On the one hand, this suppresses the lateral charge transport at the interface between the first composite sublayer and the bottom cell, and on the other hand, it suppresses the lateral charge transport at the interface between the second composite sublayer and the top cell. Furthermore, based on the aforementioned resistivity range, by adjusting the carrier concentration of the first composite sublayer to be greater than that of the second composite sublayer, the Fermi level of the first composite sublayer is shifted upward, achieving energy level matching between the first composite sublayer and the N-type doped layer, reducing the contact barrier between the interface of the first composite sublayer and the N-type doped layer, and promoting the transport of electrons from the bottom cell to the composite layer. On the other hand, the Fermi level of the second composite sublayer is shifted downward, achieving energy level matching between the second composite sublayer and the hole transport layer, reducing the interface contact barrier between the second composite sublayer and the hole transport layer, and promoting the transport of holes from the top cell to the composite layer. In summary, the composite layer of this application has a bilayer structure, which simultaneously achieves contact energy level matching between the composite layer and the N-type doped layer of the bottom cell and the hole transport layer of the top cell. It also suppresses the lateral transport of charge on the surface of the composite layer, promotes the transport of charge at the interface, reduces open-circuit voltage loss, and improves the open-circuit voltage and fill factor of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

[0043] As some examples of this embodiment, the resistivity of the first composite sublayer 21 and / or the resistivity of the second composite sublayer 22 may be 6.5 × 10⁻⁶. -4 Ω·cm, 6.75×10 -4 Ω·cm, 6.96×10 -4 Ω·cm, 9×10 -4 Ω·cm, 1×10 -3 Ω·cm, 1.36×10 -3 Ω·cm, 1.59×10 -3 Ω·cm, 1.60×10 -3 Ω·cm, 1.61×10 -3 Ω·cm, 2.67×10 -3 Ω·cm, 5×10 -3 Ω·cm, 5.67×10 -3 Ω·cm, 1×10 -2 Ω·cm, 1.18×10 -2 Ω·cm, 1.42×10 -2 Ω·cm, 1.47×10 -2 Ω·cm, 1.6×10 -2 Ω·cm, or the resistivity of the first composite sublayer 21 and / or the resistivity of the second composite sublayer 22 may be between any two of the above resistivity.

[0044] In one optional embodiment, the carrier concentration of the first composite sublayer is C1, and the carrier concentration of the second composite sublayer is C2, 7.0 × 10⁻⁶. 20 pcs / cm 3 ≤C1≤1.0×10 21 pcs / cm 3 1.0×10 19 pcs / cm 3 ≤C2≤2.5×10 20 pcs / cm 3 By adjusting the carrier concentrations C1 and C2 of the first and second composite sublayers within the aforementioned ranges, electron transport from the bottom cell to the composite layer and hole transport from the top cell to the composite layer are promoted, reducing open-circuit voltage loss and promoting longitudinal charge transport. Furthermore, the lower carrier concentration of the second composite sublayer can, to some extent, increase its resistivity and suppress lateral charge transport at the interface between the second composite sublayer and the top cell. Under the combined effect of these factors, the open-circuit voltage and fill factor are improved, thereby contributing to the improvement of the solar cell's photoelectric conversion efficiency.

[0045] As some examples of this embodiment, the value of C1 can be 7.00 × 10. 20 pcs / cm 3 7.50×10 20 pcs / cm 3 8.00×10 20 pcs / cm 3 8.15×10 20 pcs / cm 3 8.48×10 20 pcs / cm 3 8.50×10 20 pcs / cm 3 8.59×10 20 pcs / cm 3 9.00×10 20 pcs / cm 3 1.00×10 21 pcs / cm 3 Alternatively, the value of C1 can be either of the two values ​​mentioned above.

[0046] As some examples of this embodiment, the value of C2 can be 1.0 × 10. 19 pcs / cm 3 1.06×10 19 pcs / cm 3 1.10×10 19 pcs / cm 3 1.35×10 19pcs / cm 3 3.0×10 19 pcs / cm 3 5.0×10 19 pcs / cm 3 6.10×10 19 pcs / cm 3 7.0×10 19 pcs / cm 3 9.0×10 19 pcs / cm 3 1.0×10 20 pcs / cm 3 1.36×10 20 pcs / cm 3 2.5×10 20 pcs / cm 3 Alternatively, C2 can take any of the two values ​​mentioned above.

[0047] In one optional embodiment, the carrier mobility of the first composite sublayer is CM1, and the carrier mobility of the second composite sublayer is CM2, where CM1 < CM2. By adjusting the carrier mobility CM1 of the first composite sublayer to be less than that of the second composite sublayer, the resistivity of the first composite sublayer can be increased to a certain extent, thereby suppressing lateral charge transport at the interface between the first composite sublayer and the bottom cell. This is beneficial for improving the open-circuit voltage and fill factor, and thus for improving the photoelectric conversion efficiency of the solar cell.

[0048] In one alternative implementation, 1cm 2 / V·s≤CM1≤13cm 2 / V·s, 30cm 2 / V·s≤CM2≤40cm 2 / V·s. By adjusting the carrier mobility CM1 of the first composite sublayer and the carrier mobility CM2 of the second composite sublayer within the above range, making the carrier mobility CM1 of the first composite sublayer smaller than the carrier mobility CM2 of the second composite sublayer, the resistivity of the first composite sublayer can be increased to a certain extent, thereby suppressing the lateral charge transport at the contact interface between the first composite sublayer and the bottom cell. This is beneficial to improving the open-circuit voltage and fill factor, and thus to improving the photoelectric conversion efficiency of the solar cell.

[0049] As some examples of this embodiment, the value of CM1 can be 1cm. 2 / V·s、1.1cm 2 / V·s、2cm 2 / V·s、3cm 2 / V·s、4.5cm 2 / V·s、4.6cm2 / V·s、4.8cm 2 / V·s、5cm 2 / V·s、7cm 2 / V·s、8cm 2 / V·s、10cm 2 / V·s、11cm 2 / V·s、12cm 2 / V·s、12.8cm 2 / V·s、13cm 2 / V·s, or, the value of CM1 can be between any two of the above values.

[0050] As some examples of this embodiment, the value of CM2 can be 30cm. 2 / V·s、30.5cm 2 / V·s、31cm 2 / V·s、32cm 2 / V·s、33cm 2 / V·s、33.8cm 2 / V·s、34cm 2 / V·s、35cm 2 / V·s、36cm 2 / V·s、37cm 2 / V·s、38cm 2 / V·s、38.3cm 2 / V·s、39cm 2 / V·s、39.3cm 2 / V·s、39.8cm 2 / V·s、40.0cm 2 / V·s, or, the value of CM2 can be between any two of the above values.

[0051] In one alternative embodiment, the resistivity of the first composite sublayer is R1, 6.5 × 10⁻⁶. -4 Ω·cm≤R1≤6.5×10 -3 Ω·cm, the resistivity of the second composite sublayer is R2, 8.0 × 10⁻⁶. -4 Ω·cm≤R2≤1.6×10 -2The resistivity of the first and second composite sublayers is Ω·cm. The first and second composite sublayers possess suitable resistivity, which suppresses lateral charge transport at the interface between the first composite sublayer and the bottom cell, and also suppresses lateral charge transport at the interface between the second composite sublayer and the top cell. This is beneficial for improving the open-circuit voltage and fill factor, thereby improving the photoelectric conversion efficiency of the solar cell. Furthermore, by synergistically controlling the carrier concentration and carrier mobility of the first composite sublayer within the scope of this application, it is advantageous to obtain a first composite sublayer with the aforementioned resistivity range; similarly, by synergistically controlling the carrier concentration and carrier mobility of the second composite sublayer within the scope of this application, it is advantageous to obtain a second composite sublayer with the aforementioned resistivity range.

[0052] As some examples of this embodiment, the value of R1 can be 6.5 × 10⁻⁶. -4 Ω·cm, 6.96×10 -4 Ω·cm, 7.0×10 -4 Ω·cm, 7.5×10 -4 Ω·cm, 8.0×10 -4 Ω·cm, 8.5×10 -4 Ω·cm, 9.0×10 -4 Ω·cm, 9.5×10 -4 Ω·cm, 1.0×10 -3 Ω·cm, 1.59×10 -3 Ω·cm, 1.60×10 -3 Ω·cm, 1.61×10 -3 Ω·cm, 3.0×10 -3 Ω·cm, 5.0×10 -3 Ω·cm, 5.67×10 -3 Ω·cm, 6.5×10 -3 Ω·cm, or, the value of R1 can be between any two of the above values.

[0053] As some examples of this embodiment, the value of R2 can be 8.0 × 10⁻⁶. -4 Ω·cm, 8.5×10 -4 Ω·cm, 9.0×10 -4 Ω·cm, 9.5×10 -4 Ω·cm, 1.0×10 -3 Ω·cm, 1.36×10 -3 Ω·cm, 1.60×10 -3 Ω·cm, 2.67×10 -3 Ω·cm, 3.0×10 -3 Ω·cm, 5.0×10 -3 Ω·cm, 7.0×10 -3Ω·cm, 9.0×10 -3 Ω·cm, 1.0×10 -2 Ω·cm, 1.18×10 -2 Ω·cm, 1.42×10 -2 Ω·cm, 1.47×10 -2 Ω·cm, 1.60×10 -2 Ω·cm, or R2 can be any of the two values ​​mentioned above.

[0054] In one optional embodiment, the work function of the first composite sublayer is 3.4 eV to 3.8 eV, and the work function of the second composite sublayer is 4.3 eV to 5.0 eV. In this application, the work function refers to the energy required for an electron to rise from the Fermi level to its rest state outside the surface (i.e., the vacuum level). By adjusting the work functions of the first and second composite sublayers within the aforementioned ranges, it is beneficial to reduce the contact potential between the composite layer and the bottom N-type doped layer, as well as between the composite layer and the top hole transport layer, allowing electrons in the bottom N-type doped layer to be smoothly transported to the top hole transport layer, while simultaneously reducing the contact resistance at the interface.

[0055] As some examples of this embodiment, the work function of the first composite sublayer can be 3.4eV, 3.5eV, 3.6eV, 3.7eV, or 3.8eV, or the work function of the first composite sublayer can be between any two of the above work functions.

[0056] As some examples of this embodiment, the work function of the second composite sublayer can be 4.3eV, 4.4eV, 4.5eV, 4.6eV, 4.7eV, 4.8eV, 4.9eV, or 5.0eV, or the work function of the second composite sublayer can be between any two of the above work functions.

[0057] In one optional embodiment, the thickness of the first composite sublayer is H1, and the thickness of the second composite sublayer is H2, where 0 nm ≤ H2 - H1 ≤ 14 nm. The inventors have found that if the thickness difference between the first and second composite sublayers is too large, it will affect the performance of the first composite sublayer, causing a change in the carrier concentration and consequently worsening the contact with the N-type doped layer. Therefore, H2 - H1 should not be too large. This application, by controlling the thickness difference between the first and second composite sublayers, i.e., H2 - H1, within the aforementioned range, facilitates the use of the high carrier mobility of the second composite sublayer to achieve rapid electron transport and avoid interface charge accumulation.

[0058] As some examples of this embodiment, the values ​​of H2-H1 can be 0nm, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 10nm, 12nm, 13nm, 14nm, or the values ​​of H2-H1 can be between any two of the above values.

[0059] In one optional implementation, 1nm ≤ H1 ≤ 5nm, and 3nm ≤ H2 ≤ 15nm. By adjusting the thickness H1 of the first composite sublayer and the thickness H2 of the second composite sublayer within the above ranges, it is not only beneficial to achieve good energy level matching between the composite layer and the N-type layer and the hole transport layer, but also to achieve rapid electron transport and avoid interface charge accumulation.

[0060] As some examples of this embodiment, the value of H1 can be 1nm, 2nm, 3nm, 4nm, 5nm, or the value of H1 can be between any two of the above values.

[0061] As some examples of this embodiment, the value of H2 can be 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 10nm, 12nm, 13nm, 14nm, or 15nm, or the value of H2 can be between any two of the above values.

[0062] In some embodiments of this application, the materials of the first composite sublayer and / or the second composite sublayer include at least one of indium zinc oxide (IZO), indium tin oxide (ITO), aluminum zinc oxide (AZO), tungsten-doped indium oxide (IWO), and cerium-doped indium oxide (ICO).

[0063] In one optional embodiment, referring to FIG1, the bottom cell 1 includes a silicon substrate 13, the light-receiving surface of the silicon substrate 13 is provided with a first intrinsic amorphous silicon layer 12 and an N-type doped layer 11 stacked sequentially, and the backlight surface of the silicon substrate 13 is provided with a second intrinsic amorphous silicon layer 14, a P-type doped layer 15 and a second transparent electrode layer 16 stacked sequentially.

[0064] In an alternative embodiment, referring to FIG1, a hole modification layer 32, a perovskite layer 33, a passivation layer 34, an electron transport layer 35, a buffer layer 36, a first transparent electrode layer 37, and an antireflection layer 38 are also stacked sequentially on the hole transport layer 31.

[0065] This application does not impose any particular restrictions on the electrodes of the solar cell, as long as they can achieve the purpose of this application. For example, referring to Figure 1, a positive electrode 4 can be provided on the light-receiving surface of the solar cell, and a back electrode 5 can be provided on the back surface of the solar cell.

[0066] In related technologies, composite layers can be prepared using solution methods. However, solution methods require multiple steps such as solution preparation, spin coating, and annealing, which are cumbersome and time-consuming. In addition, the light-receiving surface of the bottom cell usually has a pyramid-shaped textured structure. Solution methods can result in the pyramid having thicker valleys and thinner peaks, leading to uneven composite layer coverage, which is not conducive to the mass production of large-area and uniformly covered composite layer films. Furthermore, the use of deionized water in the solution can cause defects in the amorphous silicon of the bottom cell and produce an insulating SiO2 layer, increasing the contact resistance between the bottom cell and the composite layer and reducing the cell fill factor. On the other hand, the low resistivity of the composite layer prepared by solution methods makes it easy for charge to transport laterally on the surface of the composite layer, resulting in lateral current shunting and hindering the longitudinal transport of charge, thus affecting the photoelectric conversion efficiency of the solar cell.

[0067] In view of this, secondly, this application provides a method for fabricating a solar cell as described in the first aspect, comprising the following steps:

[0068] Step A: Provide a base cell, and sequentially prepare a first composite sublayer and a second composite sublayer on the surface of the N-type doped layer of the base cell by magnetron sputtering to form a composite layer, wherein the oxygen flow rate introduced to prepare the second composite sublayer is greater than the oxygen flow rate introduced to prepare the first composite sublayer.

[0069] Step B: Sequentially prepare other functional layers on the surface of the composite layer. The other functional layers include at least a hole transport layer, a hole modification layer, and a perovskite layer.

[0070] In step A, a first composite sublayer can be prepared on the surface of the N-type doped layer of the bottom cell by magnetron sputtering, and then a second composite sublayer can be prepared on the surface of the first composite sublayer to form a composite layer.

[0071] This application does not impose any particular limitation on the target materials for the first and second composite sublayers, as long as they can achieve the purpose of this application. For example, the target materials for the first and second composite sublayers include transparent conductive oxide (TCO) materials, including but not limited to indium zinc oxide (IZO), indium tin oxide (ITO), aluminum zinc oxide (AZO), tungsten-doped indium oxide (IWO), or cerium-doped indium oxide (ICO).

[0072] In step B, other functional layers can be prepared on the surface of the composite layer by magnetron sputtering. For example, a hole transport layer, a hole modification layer, a perovskite layer, and a passivation layer can be prepared sequentially on the surface of the second composite sublayer. The hole transport layer is made of nickel oxide, and its thickness is 10 nm to 25 nm. As examples of this embodiment, the thickness of the hole transport layer can be 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, or 25 nm. Alternatively, the thickness of the hole transport layer can be between any two of the above thicknesses. This application does not impose any particular limitation on the material of the hole modification layer; for example, it can be selected from [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), [4-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), and [4-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz). Materials such as [-9H-carbazole-9-yl)butylphosphonic acid (MeO-4PACz) and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) can be used to prepare hole-modifying layers with a thickness of 0.5 nm to 1.5 nm on the surface of the hole transport layer by spin coating or slot coating. As some examples of this embodiment, the thickness of the hole-modifying layer can be 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1.0 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, or 1.5 nm, or the thickness of the hole-modifying layer can be between any two of the above thicknesses. When preparing the perovskite layer, a framework layer can be prepared first, and then an organic salt solution can be spin-coated onto the surface of the framework layer, followed by thermal annealing to obtain the perovskite layer. The framework layer can be obtained by vapor deposition of PbI2 and CsX (X represents a halogen element). This application does not impose any particular limitation on the type of organic salt. For example, at least two of the following can be combined and dissolved in a solvent to obtain an organic salt solution: formamidine hydroiodide (FAI), formamidine hydrobromide (FABr), formamidine hydrochloride (FACl), methylamine iodide (MAI), methylamine bromide (MABr), and methylamine chloride (MACl). This application also does not impose any particular limitation on the coating method. For example, spin coating, spray coating, slot coating, and doctor blade coating can be used.The thickness of the perovskite layer is 400 nm to 500 nm. As some examples of this embodiment, the thickness of the perovskite layer can be 420 nm, 440 nm, 450 nm, 470 nm, 480 nm, 490 nm, or 500 nm, or the thickness of the perovskite layer can be between any two of the above thicknesses. A LiF film layer with a thickness of 1 nm to 2 nm is prepared on the surface of the perovskite layer as a passivation layer by metal evaporation. As some examples of this embodiment, the thickness of the passivation layer can be 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.7 nm, 1.9 nm, or 2 nm, or the thickness of the passivation layer can be between any two of the above thicknesses.

[0073] In one optional embodiment, the oxygen flow rate introduced into the preparation of the first composite sublayer is F1, where 0 Sccm ≤ F1 ≤ 6 Sccm, and the oxygen flow rate introduced into the preparation of the second composite sublayer is F2, where 20 Sccm ≤ F2 - F1 ≤ 50 Sccm. By controlling the difference between F2 and F1 within the above range, the carrier concentrations of the first and second composite sublayers can be adjusted, thereby controlling the Fermi levels of the first and second composite sublayers. This allows for adjustable work functions of the first and second composite sublayers, which is beneficial for obtaining the composite layer of this application.

[0074] As some examples of this embodiment, the value of F1 can be 0Sccm, 1Sccm, 2Sccm, 3Sccm, 4Sccm, 5Sccm, 6Sccm, or the value of F1 can be between any two of the above values.

[0075] As some examples of this embodiment, the values ​​of F2-F1 can be 20Sccm, 25Sccm, 26Sccm, 30Sccm, 35Sccm, 38Sccm, 40Sccm, 45Sccm, 48Sccm, or 50Sccm, or the values ​​of F2-F1 can be between any two of the above values.

[0076] In one optional embodiment, when the first and second composite sublayers are prepared by magnetron sputtering, the sputtering pressure of the magnetron sputtering method is 0.3 Pa to 1.0 Pa, the temperature is 23 °C to 200 °C, the flow rate of argon gas is 500 Sccm to 1200 Sccm, and the sputtering power of the target material is 100 W to 2000 W; and / or, the coating transfer rate of the first composite sublayer is 4.1 mm / s to 495.0 mm / s, preferably 45.0 mm / s to 225.0 mm / s; and the coating transfer rate of the second composite sublayer is 1.4 mm / s to 165.0 mm / s, preferably 15.0 mm / s to 75.0 mm / s.

[0077] As some examples of this embodiment, the sputtering pressure of magnetron sputtering can be 0.3 Pa, 0.4 Pa, 0.5 Pa, 0.6 Pa, 0.7 Pa, 0.8 Pa, 0.9 Pa, or 1.0 Pa, or the sputtering pressure of magnetron sputtering can be between any two of the above values.

[0078] As some examples of this embodiment, the sputtering temperature of magnetron sputtering can be 23°C, 28°C, 30°C, 35°C, 40°C, 50°C, 70°C, 90°C, 120°C, 140°C, 150°C, 170°C, 180°C, 190°C, or 200°C, or the sputtering temperature of magnetron sputtering can be between any two of the above values.

[0079] As some examples of this embodiment, the flow rate of argon gas introduced by magnetron sputtering can be 500 Sccm, 600 Sccm, 700 Sccm, 800 Sccm, 900 Sccm, 1000 Sccm, 1100 Sccm, or 1200 Sccm, or the flow rate of argon gas introduced by magnetron sputtering can be between any two of the above values.

[0080] As some examples of this embodiment, the sputtering power of the magnetron sputtering target can be 100W, 300W, 500W, 700W, 900W, 1000W, 1200W, 1400W, 1500W, 1700W, 1900W, or 2000W, or the sputtering power of the magnetron sputtering target can be between any two of the above values.

[0081] As some examples of this embodiment, the deposition transfer rate of the first composite sublayer by magnetron sputtering can be 4.1 mm / s, 10 mm / s, 45 mm / s, 50 mm / s, 75 mm / s, 100 mm / s, 150 mm / s, 200 mm / s, 225 mm / s, 250 mm / s, 300 mm / s, 350 mm / s, 400 mm / s, 450 mm / s, or 495.0 mm / s. Alternatively, the deposition transfer rate of the first composite sublayer by magnetron sputtering can be between any two of the above values.

[0082] As some examples of this embodiment, the deposition transfer rate of the second composite sublayer by magnetron sputtering can be 1.4 mm / s, 10 mm / s, 15 mm / s, 30 mm / s, 32.1 mm / s, 50 mm / s, 70 mm / s, 75 mm / s, 100 mm / s, 130 mm / s, 150 mm / s, or 165.0 mm / s. Alternatively, the deposition transfer rate of the second composite sublayer by magnetron sputtering can be between any two of the above values.

[0083] In one optional embodiment, the preparation method further includes:

[0084] An electron transport layer, a buffer layer, a first transparent electrode layer, and an antireflection layer are sequentially fabricated on the surface of the passivation layer.

[0085] This application does not impose any particular limitations on the fabrication methods of the electron transport layer, buffer layer, first transparent electrode layer, antireflection layer, and electrodes. For example, the electron transport layer material C can be used. 60 An electron transport layer with a thickness of 10 nm to 20 nm is obtained by thermal evaporation deposition using a metal evaporation device. As examples of this embodiment, the thickness of the electron transport layer can be 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, or 20 nm, or any two of the above thicknesses. A buffer layer material, SnO2, can be obtained by atomic layer deposition (ALD) with a thickness of 10 nm to 17 nm. As examples of this embodiment, the thickness of the buffer layer can be 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, or 17 nm, or any two of the above thicknesses. A first transparent electrode layer with a thickness of 30 nm to 110 nm can be obtained by magnetron sputtering using indium zinc oxide (IZO) as the transparent electrode layer material. As examples of this embodiment, the thickness of the first transparent electrode layer can be... The thickness of the first transparent electrode layer can be 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, or 110nm, or it can be between any two of the above thicknesses. The antireflective layer material, LiF or MgF2, can be thermally evaporated and deposited using a metal evaporation device to obtain the antireflective layer, with a thickness of 80nm to 130nm. As some examples of this embodiment, the thickness of the antireflective layer can be 80nm, 90nm, 100nm, 110nm, 120nm, or 130nm, or it can be between any two of the above thicknesses. The electrode material, Ag, can be thermally evaporated and deposited using a metal evaporation device to obtain the positive electrode and the back electrode, with an electrode thickness of 300nm to 500nm. As some examples of this embodiment, the electrode thickness can be 300nm, 320nm, 350nm, 400nm, 420nm, 450nm, or 500nm, or it can be between any two of the above thicknesses.

[0086] The base cell of this application can be a commercially available or industrially produced silicon-based cell. In one optional embodiment, the base cell is prepared by the following steps:

[0087] 1) A first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer are fabricated on the light-receiving side and the back-light-receiving side of an N-type silicon wafer (i.e., a silicon substrate), respectively. The thickness of the first intrinsic amorphous silicon layer is 5 nm to 12 nm. As some examples of this embodiment, the thickness of the first intrinsic amorphous silicon layer can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, or 12 nm, or it can be between any two of the above thicknesses. The thickness of the second intrinsic amorphous silicon layer is 5 nm to 12 nm. As some examples of this embodiment, the thickness of the second intrinsic amorphous silicon layer can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, or 12 nm, or it can be between any two of the above thicknesses.

[0088] 2) An N-type doped layer is prepared on the surface of the first intrinsic amorphous silicon layer, and a P-type doped layer is prepared on the surface of the second intrinsic amorphous silicon layer. The thickness of the N-type doped layer is 5 nm to 25 nm. As examples of this embodiment, the thickness of the N-type doped layer can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 15 nm, 20 nm, 22 nm, or 25 nm, or the thickness of the N-type doped layer can be between any two of the above thicknesses. The thickness of the P-type doped layer is 10 nm to 30 nm. As examples of this embodiment, the thickness of the P-type doped layer can be 10 nm, 12 nm, 15 nm, 20 nm, 22 nm, 25 nm, 28 nm, or 30 nm, or the thickness of the P-type doped layer can be between any two of the above thicknesses.

[0089] 3) A second transparent electrode layer of ITO material is prepared on the surface of the P-type doped layer using DC or RF magnetron sputtering process. The thickness of the second transparent electrode layer is 90nm to 120nm. As some examples of this embodiment, the thickness of the second transparent electrode layer can be 90nm, 95nm, 100nm, 105nm, 110nm, 115nm, or 120nm, or the thickness of the second transparent electrode layer can be between any two of the above thicknesses.

[0090] In one alternative embodiment, the light-receiving surface of the silicon substrate has a textured structure. To better absorb solar energy, the light-receiving surface of the silicon substrate has a textured structure; for example, the textured structure can be a pyramid-shaped textured structure. This textured structure allows for a higher surface area for the solar cell while reducing light reflection and diffusion. This application does not impose any particular limitation on the method of preparing the textured structure, as long as it achieves the purpose of this application.

[0091] It is understood that after obtaining the bottom cell, the composite layer of this application can be prepared on the surface of the N-type doped layer of the bottom cell. The top cell of this application can be a single-junction perovskite solar cell.

[0092] The solar cell fabrication method provided in this application produces a composite layer comprising a first composite sublayer and a second composite sublayer. Compared to existing solution methods, this method offers advantages such as simpler fabrication processes and easier operation. Furthermore, this application sequentially forms the first and second composite sublayers using magnetron sputtering. The magnetron sputtering target creates a uniformly distributed target atom region, ensuring that target atoms are uniformly attached to the textured surface in all directions. Moreover, the target atoms possess high energy and strong adhesion to the pyramid surface, preventing atoms from detaching and falling into the pyramid's valleys. This avoids a situation where the valleys are too thick and the pyramid peaks are too thin, thus achieving uniform coverage of the pyramid by the magnetron sputtering film. This method is beneficial for industrial production and suitable for large-scale manufacturing of tandem solar cells.

[0093] Thirdly, this application provides a photovoltaic module, which includes a solar cell as described in the first aspect, or the photovoltaic module includes a solar cell prepared by the preparation method described in the second aspect.

[0094] This application also provides a photovoltaic module for converting received light energy into electrical energy and transmitting it to an external load. The photovoltaic module includes: at least one cell string, which is composed of multiple solar cells connected together; an encapsulating film for covering the surface of the cell string; and a cover plate for covering the surface of the encapsulating film facing away from the cell string.

[0095] Example

[0096] The solar cells, their fabrication methods, and photovoltaic modules of this application will be further described below with reference to more specific embodiments.

[0097] Example 1

[0098] <Preparation of Composite Layer>

[0099] <Preparation of the first composite sublayer>

[0100] A bottom cell is provided, wherein the thickness of the N-type doped layer is 6nm, the thickness of the first intrinsic amorphous silicon layer is 8nm, the thickness of the N-type silicon wafer is 120μm, the thickness of the second intrinsic amorphous silicon layer is 8nm, the thickness of the P-type doped layer is 10nm, and the thickness of the second transparent electrode layer is 100nm.

[0101] Using an IZO target, the first composite sublayer was prepared on the surface of the N-type doped layer on the light-receiving surface of the bottom cell by magnetron sputtering. The sputtering pressure, temperature, argon gas flow rate, target RF sputtering power, coating transmission rate, oxygen flow rate F1, and thickness H1 of the first composite sublayer are shown in Table 1.

[0102] <Preparation of the Second Composite Sublayer>

[0103] IZO target material was selected, and a second composite sublayer was prepared on the surface of the first composite sublayer by magnetron sputtering. The sputtering pressure, temperature, argon gas flow rate, target RF sputtering power, coating transmission rate, oxygen flow rate F2, and thickness H2 of the second composite sublayer are shown in Table 2.

[0104] <Preparation of Hole Transport Layer>

[0105] Nickel oxide (NiO) was selected x A hole transport layer with a thickness of 20 nm was prepared on the surface of the second composite sublayer using a target material and a radio frequency magnetron sputtering method.

[0106] <Preparation of Hole Modification Layer>

[0107] SAM material 2-PACz was prepared on the surface of the hole transport layer by solution spin coating to form a hole modification layer with a thickness of 1 nm.

[0108] <Preparation of Perovskite Layer>

[0109] First, a framework layer is deposited on the surface of the hole-modified layer by vapor deposition. The framework layer can be obtained by vapor deposition of PbI2 and CsBr. Then, an organic salt cation is spin-coated onto the surface of the framework layer. After the organic salt cation reacts fully with the framework layer, a perovskite layer with a thickness of 450 nm is obtained.

[0110] <Preparation of Passivation Layer>

[0111] A 1 nm thick LiF film was prepared on the surface of the perovskite layer as a passivation layer using a metal vapor deposition method.

[0112] <Preparation of other functional layers>

[0113] An electron transport layer, a buffer layer, and a first transparent electrode layer are sequentially prepared on the surface of the passivation layer.

[0114] The electron transport layer is fabricated by depositing a 20nm thick C layer on the perovskite layer. 60 As an electron transport layer;

[0115] The preparation process of the buffer layer is as follows: a 10 nm thick tin dioxide layer is prepared on the electron transport layer using atomic layer deposition as a buffer layer;

[0116] The preparation process of the first transparent electrode layer is as follows: a 100 nm thick layer of IZO is prepared on the buffer layer using a magnetron sputtering device as the first transparent electrode layer.

[0117] <Solar Cell Fabrication>

[0118] A 350 nm thick silver layer was prepared on the first transparent electrode layer by thermal evaporation as the positive electrode, and a 300 nm thick silver layer was prepared on the second transparent electrode layer of the bottom cell by thermal evaporation as the back electrode. Then, MgF2 was thermally evaporated and deposited through a metal evaporation device to obtain an anti-reflection layer with a thickness of 100 nm, thus obtaining a solar cell. The cell structure is shown in Figure 1.

[0119] Examples 2 to 8

[0120] Except for adjusting the oxygen flow rate F1 when preparing the first composite sublayer, the oxygen flow rate F2 when preparing the second composite sublayer, the thickness H1 of the first composite sublayer, and the thickness H2 of the second composite sublayer according to Tables 1 and 2 respectively in the <Preparation of Composite Layer>, the other conditions are the same as in Example 1, and the solar cell is finally obtained.

[0121] Example 9

[0122] The difference from Example 1 is that in the <Preparation of Composite Layer>, the oxygen flow rate F1 when preparing the first composite sublayer, the oxygen flow rate F2 when preparing the second composite sublayer, the thickness H1 of the first composite sublayer, and the thickness H2 of the second composite sublayer are adjusted according to Table 1 and Table 2 respectively, so that CM1 = CM2 (see Table 4 for details), and finally a solar cell is obtained.

[0123] Example 10

[0124] The difference from Example 1 is that in the <Preparation of Composite Layer>, the oxygen flow rate F1 when preparing the first composite sublayer, the oxygen flow rate F2 when preparing the second composite sublayer, the thickness H1 of the first composite sublayer, and the thickness H2 of the second composite sublayer are adjusted according to Table 1 and Table 2 respectively, so that CM1 > CM2 (see Table 4 for details), and finally a solar cell is obtained.

[0125] Example 11

[0126] The difference from Example 1 is that in the <Preparation of Composite Layer>, the oxygen flow rate F1 when preparing the first composite sublayer, the oxygen flow rate F2 when preparing the second composite sublayer, the thickness H1 of the first composite sublayer, and the thickness H2 of the second composite sublayer are adjusted according to Table 1 and Table 2 respectively, so that H2-H1<0 (see Table 3 for details), and finally a solar cell is obtained.

[0127] Example 12

[0128] The difference from Example 1 is that in the <Preparation of Composite Layer>, the oxygen flow rate F1 when preparing the first composite sublayer, the oxygen flow rate F2 when preparing the second composite sublayer, the thickness H1 of the first composite sublayer, and the thickness H2 of the second composite sublayer are adjusted according to Table 1 and Table 2 respectively, so that F2-F1=15Sccm (see Table 3 for details), and finally a solar cell is obtained.

[0129] Comparative Example 1

[0130] Except for the fact that the composite layer is a single-layer structure, the other conditions are the same as in Example 1. The preparation process of the single-layer composite layer is as follows:

[0131] Using an IZO target, a composite layer was prepared on the surface of the N-type doped layer on the light-receiving surface of the bottom cell by magnetron sputtering. The sputtering pressure, temperature, argon gas flow rate, target RF sputtering power, coating transmission rate, oxygen flow rate F1, and thickness H1 of the first composite sublayer are shown in Table 1. Finally, the solar cell was obtained.

[0132] Comparative Example 2

[0133] Except for adjusting the oxygen flow rate F1 when preparing the first composite sublayer and the oxygen flow rate F2 when preparing the second composite sublayer according to Tables 1 and 2 respectively in the <Preparation of Composite Layer> section, the other conditions are the same as in Example 1, and the solar cell is finally obtained.

[0134] Comparative Example 3

[0135] The difference from Example 1 is that in the <Preparation of Composite Layer>, the oxygen flow rate F1 when preparing the first composite sublayer, the oxygen flow rate F2 when preparing the second composite sublayer, the thickness H1 of the first composite sublayer, and the thickness H2 of the second composite sublayer are adjusted according to Table 1 and Table 2, respectively, and the resistivity of the first composite sublayer and the resistivity of the second composite sublayer are adjusted (see Table 4 for details) to finally obtain the solar cell.

[0136] The oxygen flow rate difference and thickness difference between the second composite sublayer and the first composite sublayer in the above embodiments and comparative examples are shown in Table 3. The relevant performance data of the composite layer in each embodiment and comparative example are shown in Table 4.

[0137] Table 1: Preparation parameters of the first composite sublayer in each embodiment and comparative example

[0138] Table 2: Preparation parameters of the second composite sublayer in each embodiment and comparative example

[0139] In Table 2, " / " indicates that no relevant preparation parameters exist.

[0140] Table 3: Difference in oxygen flow rate and thickness between the second and first composite sublayers

[0141] In Table 3, " / " indicates that no relevant preparation parameters exist.

[0142] Table 4: Composite layer performance data for each embodiment and comparative example

[0143] In Table 4, " / " indicates that there is no relevant performance data.

[0144] Performance testing:

[0145] Open circuit voltage, short circuit current, and fill factor tests:

[0146] The current (I)-voltage (V) of the solar cells in each embodiment and comparative example were measured using the Wavelabs solar simulator to obtain the open-circuit voltage (Voc), short-circuit current (Jsc), and fill factor (FF) of the solar cells.

[0147] Photoelectric conversion efficiency test:

[0148] The current (I)-voltage (V) of the solar cells in each embodiment and comparative example were measured using the Wavelabs solar simulator to obtain the photoelectric conversion efficiency (PCE) of the solar cells.

[0149] The test results are listed in Table 5.

[0150] Table 5: Solar cell performance data for each embodiment and comparative example

[0151] As can be seen from Examples 1-12 and Comparative Examples 1-3, the open-circuit voltage and fill factor of the solar cell in Comparative Example 1 are relatively low, resulting in a low photoelectric conversion efficiency. This may be because the composite layer of the single film layer in Comparative Example 1 cannot simultaneously achieve energy level matching with the N-type doped layer and the hole transport layer, thus creating a high contact barrier at the contact interface, hindering the transport of electrons from the bottom cell and holes from the top cell, leading to charge accumulation and resulting in a loss of open-circuit voltage and fill factor. The photoelectric conversion efficiency of the solar cell in Comparative Example 2 is also relatively low, which may be due to the introduction of the second composite sublayer. The oxygen flow rate F2 was significantly lower than that introduced during the preparation of the first composite sublayer (F1), resulting in a lower carrier concentration in the first composite sublayer compared to the second composite sublayer. This caused the first composite sublayer to have a lower energy level match with the N-type doped layer, increasing the interfacial barrier between them and hindering electron transport from the bottom cell to the composite layer. Conversely, the second composite sublayer also had difficulty achieving energy level matching with the hole transport layer, increasing the interfacial barrier and hindering hole transport from the top cell to the composite layer. However, the photoelectric conversion efficiency of the solar cell in this application was significantly improved compared to Comparative Examples 1 and 2, with a maximum improvement of nearly 1.5 percentage points, indicating that the solar cell with the double-layer composite structure of this application possesses excellent photoelectric conversion performance. Compared to Example 1, Comparative Example 3 controlled the resistivity of the first and second composite sublayers to be 6.5 × 10⁻⁶. -4 Ω·cm~1.6×10 -2 Outside the Ω·cm range, the PCE and FF values ​​of solar cells are significantly reduced.

[0152] The thickness of the first composite sublayer, the thickness of the second composite sublayer, and the oxygen flow rate typically affect the performance of the composite layer. As can be seen from Examples 2 to 8, by adjusting the above-mentioned preparation parameters within the scope of this application, it is beneficial to reduce open-circuit voltage loss, improve the open-circuit voltage and fill factor of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell. As can be seen from Examples 9 to 12, compared with Example 1, controlling CM1 = CM2 in Example 9, controlling CM1 > CM2 in Example 10, controlling H2 - H1 < 0 in Example 11, and controlling F2 - F1 = 15 Sccm in Example 12 slightly reduces the PCE and FF values ​​of the solar cell.

[0153] The present application discloses a solar cell, its preparation method, and a photovoltaic module. Specific examples have been used to illustrate the principles and implementation methods of the present application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of the present application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present application. Therefore, the content of this specification should not be construed as a limitation of the present application.

Claims

1. A solar cell, characterized in that, It includes a bottom cell, a composite layer, and a top cell, with the composite layer located between the bottom cell and the top cell. The light-receiving surface of the bottom cell has an N-type doped layer, and the backlighting surface of the top cell has a hole transport layer. The composite layer includes a first composite sublayer and a second composite sublayer stacked together. The side of the first composite sublayer facing away from the second composite sublayer faces the N-type doped layer, and the side of the second composite sublayer facing away from the first composite sublayer faces the hole transport layer. The carrier concentration of the first composite sublayer is greater than that of the second composite sublayer; The resistivity of the first composite sublayer and / or the resistivity of the second composite sublayer is 6.5 × 10⁻⁶. -4 Ω·cm~1.6×10 -2 Ω·cm.

2. The solar cell according to claim 1, characterized in that, The carrier concentration of the first composite sublayer is C1, and the carrier concentration of the second composite sublayer is C2, 7.0 × 10⁻⁶. 20 pcs / cm 3 ≤C1≤1.0×10 21 pcs / cm 3 1.0×10 19 pcs / cm 3 ≤C2≤2.5×10 20 pcs / cm 3 .

3. The solar cell according to claim 1 or 2, characterized in that, The carrier mobility of the first composite sublayer is CM1, and the carrier mobility of the second composite sublayer is CM2, where CM1 < CM2.

4. The solar cell according to claim 3, characterized in that, 1cm 2 / H·s≤CM1≤13cm 2 / H·s, 30cm 2 / H·s≤CM2≤40cm 2 / V·s.

5. The solar cell according to any one of claims 1 to 4, characterized in that, The resistivity of the first composite sublayer is R1, 6.5 × 10⁻⁶. -4 Ω·cm≤R1≤6.5×10 -3 Ω·cm, the resistivity of the second composite sublayer is R2, 8.0 × 10⁻⁶. -4 Ω·cm≤R2≤1.6×10 -2 Ω·cm.

6. The solar cell according to any one of claims 1 to 5, characterized in that, The work function of the first composite sublayer is 3.4 eV to 3.8 eV, and the work function of the second composite sublayer is 4.3 eV to 5.0 eV.

7. The solar cell according to any one of claims 1 to 6, characterized in that, The thickness of the first composite sublayer is H1, and the thickness of the second composite sublayer is H2, where 0nm ≤ H2 - H1 ≤ 14nm.

8. The solar cell according to claim 7, characterized in that, 1nm≤H1≤5nm, 3nm≤H2≤15nm.

9. The solar cell according to any one of claims 1 to 8, characterized in that, The materials of the first composite sublayer and / or the second composite sublayer include at least one of indium zinc oxide, indium tin oxide, zinc aluminum oxide, tungsten-doped indium oxide, and cerium-doped indium oxide.

10. The solar cell according to any one of claims 1 to 9, characterized in that, The bottom cell includes a silicon substrate, on the light-receiving surface of the silicon substrate a first intrinsic amorphous silicon layer and an N-type doped layer are stacked in sequence, and on the back-light-receiving surface of the silicon substrate a second intrinsic amorphous silicon layer, a P-type doped layer and a second transparent electrode layer are stacked in sequence.

11. The solar cell according to claim 10, characterized in that, The hole transport layer is further stacked with a hole modification layer, a perovskite layer, a passivation layer, an electron transport layer, a buffer layer, a first transparent electrode layer, and an antireflection layer in sequence.

12. A method for preparing a solar cell as described in any one of claims 1 to 11, characterized in that, Includes the following steps: A bottom cell is provided, and a first composite sublayer and a second composite sublayer are sequentially prepared on the surface of the N-type doped layer of the bottom cell by magnetron sputtering to form a composite layer, wherein the oxygen flow rate introduced to prepare the second composite sublayer is greater than the oxygen flow rate introduced to prepare the first composite sublayer. Other functional layers are sequentially prepared on the surface of the composite layer, and the other functional layers include at least a hole transport layer, a hole modification layer, and a perovskite layer.

13. The preparation method according to claim 12, characterized in that, The oxygen flow rate introduced into the first composite sublayer is F1, where 0 Sccm ≤ F1 ≤ 6 Sccm, and the oxygen flow rate introduced into the second composite sublayer is F2, where 20 Sccm ≤ F2 - F1 ≤ 50 Sccm.

14. The preparation method according to claim 12 or 13, characterized in that, The magnetron sputtering method has a sputtering pressure of 0.3 Pa to 1.0 Pa, a temperature of 23 °C to 200 °C, an argon gas flow rate of 500 Sccm to 1200 Sccm, and a target sputtering power of 100 W to 2000 W. And / or, the coating transfer rate of the first composite sublayer is 4.1 mm / s to 495.0 mm / s, and the coating transfer rate of the second composite sublayer is 1.4 mm / s to 165.0 mm / s.

15. The preparation method according to any one of claims 12 to 14, characterized in that, The preparation method further includes: An electron transport layer, a buffer layer, a first transparent electrode layer, and an antireflection layer are sequentially fabricated on the surface of the passivation layer.

16. A photovoltaic module, characterized in that, The photovoltaic module comprises the solar cell according to any one of claims 1 to 11, or the photovoltaic module comprises the solar cell prepared by the preparation method according to any one of claims 12 to 15.

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