Solar cell, preparation method thereof and photovoltaic module

Abstract

The invention discloses a solar cell and a preparation method thereof, and a photovoltaic module, the solar cell comprises a substrate, a first hole transport layer, a perovskite layer, an electron transport layer and a first electrode which are laminated from bottom to top, the substrate has a textured structure, and the first hole transport layer, the perovskite layer and the electron transport layer grow along the textured structure. The thickness of the first hole transport layer is 2nm-15nm, the material of the first hole transport layer is 2Ph-4PACz or R-2Ph-4PACz, the molecular structure of the 2Ph-4PACz is as follows: the structure of the R-2Ph-4PACz is as follows: R is one of NO2, F, Cl, Br, pyrazine or pyridine; the perovskite layer is obtained through reaction of the lead halide framework layer and a cation solution. 2Ph-4PACz or R-2Ph-4PACz is adopted as the first hole transport layer material, so that the crystallinity and shape retention of the perovskite layer with the pyramid suede structure are improved, and the conversion efficiency of the solar cell is improved.

Description

Technical Field

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

[0002] In solar cells, the pyramidal textured perovskite layer has a low light reflectivity, which is beneficial for enhancing the perovskite layer's light absorption and improving the solar cell's conversion efficiency. However, the current pyramidal textured perovskite layer has poor crystallinity and conformation, making it difficult to further improve the solar cell's conversion efficiency. Summary of the Invention

[0003] In order to improve the crystallinity and shape retention properties of the perovskite layer with a pyramidal textured surface, thereby improving the conversion efficiency of solar cells, this application provides a solar cell and its fabrication method.

[0004] In a first aspect, embodiments of the present invention provide a solar cell.

[0005] A solar cell includes a substrate, a first hole transport layer, a perovskite layer, an electron transport layer, and a first electrode stacked from bottom to top. The substrate has a textured structure, and the first hole transport layer, the perovskite layer, and the electron transport layer grow along the textured structure. The thickness of the first hole transport layer is 2 nm to 15 nm, and the material of the first hole transport layer is 2Ph-4PACz or R-2Ph-4PACz. The molecular structure of 2Ph-4PACz is as follows:

[0006]

[0007] The structure of R-2Ph-4PACz is as follows:

[0008]

[0009] R is one of NO2, F, Cl, Br, pyrazine, or pyridine;

[0010] The perovskite layer is obtained by reacting a lead halide framework layer with a cation solution.

[0011] As an optional implementation, in an embodiment of the present invention, the solar cell further includes a second hole transport layer, which is stacked on the side of the first hole transport layer away from the perovskite layer. The material of the second hole transport layer includes Cu2O, CuO, and MoO. x , NIMgLiO or NiO x One or more combinations thereof.

[0012] As an optional implementation, in an embodiment of the present invention, the thickness of the second hole transport layer is 10 nm to 20 nm.

[0013] As an optional implementation, in the embodiments of the present invention, the thickness of the perovskite layer is 600 nm to 900 nm, the thickness of the lead halide framework layer is 300 nm to 600 nm; and / or, the thickness of the electron transport layer is 10 nm to 30 nm; and / or, the thickness of the first electrode is 250 nm to 400 nm.

[0014] As an optional implementation, in an embodiment of the present invention, the substrate includes a textured base cell and a composite layer stacked on the textured base cell, and the solar cell further includes a transparent conductive layer located on the side of the first electrode near the substrate.

[0015] As an optional implementation, in an embodiment of the present invention, the solar cell further includes a passivation layer, which is stacked between the perovskite layer and the electron transport layer; and / or,

[0016] The solar cell further includes a buffer layer, which is stacked between the electron transport layer and the transparent conductive layer; and / or,

[0017] The solar cell also includes an anti-reflection layer, which is stacked on the side of the transparent conductive layer away from the substrate.

[0018] Secondly, embodiments of the present invention provide a method for preparing a solar cell.

[0019] A method for fabricating a solar cell, as mentioned in the first aspect, includes the following steps:

[0020] Provide the substrate;

[0021] Preparation of the first hole transport layer:

[0022] The 2Ph-4PACz or the R-2Ph-4PACz is placed in a solution environment to obtain a 2Ph-4PACz solution or an R-2Ph-4PACz solution. Then, the 2Ph-4PACz solution or the R-2Ph-4PACz solution is coated onto the surface of the substrate and subjected to a first annealing treatment to obtain the first hole transport layer.

[0023] Preparation of the perovskite layer:

[0024] The lead halide framework layer is prepared on the first hole transport layer;

[0025] The cationic solution is coated onto the lead halide framework layer, and the perovskite layer is obtained by a second annealing treatment.

[0026] The electron transport layer is prepared on the perovskite layer;

[0027] The first electrode is fabricated on the electron transport layer.

[0028] As an optional implementation, in an embodiment of the present invention, in the step of preparing the first hole transport layer, the concentration of the 2Ph-4PACz solution or the R-2Ph-4PACz solution is 1 mg / mL to 1.5 mg / mL, the method for coating the 2Ph-4PACz solution or the R-2Ph-4PACz solution is spin coating, the spin coating speed is 3000 rpm to 5000 rpm, and the spin coating time is 30 s to 50 s.

[0029] As an optional implementation, in the embodiments of the present invention, the solvent of the 2Ph-4PACz solution or the R-2Ph-4PACz solution is one or a mixture of anhydrous ethanol, isopropanol or cyclohexane.

[0030] As an optional implementation, in an embodiment of the present invention, the method for fabricating the solar cell further includes: fabricating a second hole transport layer between the substrate and the first hole transport layer.

[0031] As an optional implementation, in an embodiment of the present invention, the method for preparing the solar cell further includes the following steps:

[0032] A transparent conductive layer is prepared on the side of the electron transport layer opposite to the perovskite layer;

[0033] The method for preparing the substrate includes the following steps:

[0034] Provides soft-bottom batteries;

[0035] A composite layer is prepared on the textured bottom battery.

[0036] As an optional implementation, in embodiments of the present invention, a buffer layer is further prepared between the electron transport layer and the transparent conductive layer; and / or, a passivation layer is further prepared between the perovskite layer and the electron transport layer; and / or, an antireflection layer is further prepared on the side of the transparent conductive layer opposite to the substrate.

[0037] Thirdly, embodiments of the present invention provide a photovoltaic module.

[0038] A photovoltaic module includes a solar cell as mentioned in the first aspect or a solar cell prepared by the preparation method mentioned in the second aspect.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] By placing the first hole transport layer of the aforementioned thickness at the bottom of the perovskite layer, not only can the hole extraction capability be effectively improved and the non-radiative recombination at the interface be reduced, but the textured surface retention and crystallinity of the perovskite layer can also be effectively improved, overcoming the problems of poor crystallinity and poor textured surface retention of the perovskite layer on the substrate surface of the textured structure. This is because: 2Ph-4PACz or R-2Ph-4PACz has a unique structure. The benzene ring and carbazole group in the molecular end group of 2Ph-4PACz or R-2Ph-4PACz are connected by a single bond. In space, the benzene ring and carbazole group present a certain angle, which makes it difficult for 2Ph-4PACz or R-2Ph-4PACz molecules to aggregate, resulting in better coverage of the textured substrate surface. Furthermore, the introduction of benzene rings or benzene rings with R groups can enhance the interaction between the first hole transport layer and lead halide, thereby affecting the deposition distribution of lead halide on the surface of the first hole transport layer, improving the conformability of the lead halide framework layer, and thus improving the conformability and crystallinity of the perovskite layer, thereby promoting the improvement of the conversion efficiency of solar cells. The thickness of the first hole transport layer significantly affects the crystallinity and conformability of the perovskite layer. When the thickness of the first hole transport layer is too low, the interaction between 2Ph-4PACz or R-2Ph-4PACz and lead halide is relatively weak, resulting in poor conformability coverage of the lead halide framework layer. When the thickness of the first hole transport layer is too high, the series resistance of the battery increases, which is not conducive to improving the battery conversion efficiency. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the solar cell structure disclosed in an embodiment of the present invention;

[0043] Figure 2 This is a SEM image of a perovskite cross section disclosed in Embodiment 1 of the present invention;

[0044] Figure 3 This is a SEM image of a perovskite cross section disclosed in Comparative Example 1 of this invention;

[0045] Figure 4 This is a SEM image of a perovskite cross section disclosed in Comparative Example 2 of this invention;

[0046] Figure 5This is a comparison diagram of the X-ray diffraction results of the perovskite layer in Embodiment 1 and Comparative Example 1 of the present invention.

[0047] Icons: 1. Substrate; 11. Texturized base cell; 111. Second electrode; 12. Composite layer; 21. Second hole transport layer; 22. First hole transport layer; 3. Perovskite layer; 4. Passivation layer; 5. Electron transport layer; 6. Buffer layer; 7. Transparent conductive layer; 8. Antireflection layer; 9. First electrode. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] 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 invention based on the specific circumstances.

[0050] 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.

[0051] The technical solution of the present invention will be further described below with reference to the embodiments and accompanying drawings.

[0052] In a first aspect, embodiments of the present invention provide a solar cell.

[0053] Reference Figure 1 A solar cell includes a substrate 1, a first hole transport layer 22, a perovskite layer 3, an electron transport layer 5, and a first electrode 9 stacked from bottom to top. The substrate 1 has a textured structure. The first hole transport layer 22, the perovskite layer 3, and the electron transport layer 5 grow along the textured structure. The thickness of the first hole transport layer 22 is 2 nm to 15 nm. The material of the first hole transport layer 22 is 2Ph-4PACz or R-2Ph-4PACz. The molecular structure of 2Ph-4PACz is as follows:

[0054]

[0055] The structure of R-2Ph-4PACz is as follows:

[0056]

[0057] R is one of NO2, F, Cl, Br, pyrazine, or pyridine;

[0058] The perovskite layer 3 is obtained by reacting a lead halide framework layer with a cation solution.

[0059] The inventors' experiments revealed that, compared with other self-assembled materials such as 2PACz or [4-(7H-dibenzocarbazole-7-yl)butyl]phosphoric acid, setting the first hole transport layer 22 of the above thickness at the bottom of the perovskite layer 3 can not only effectively improve the hole extraction capability and reduce non-radiative recombination at the interface, but also effectively improve the texture retention and crystallinity of the perovskite layer 3, overcoming the problems of poor crystallinity and poor texture retention of the perovskite layer 3 on the surface of the textured substrate 1. This is because: 2Ph-4PACz or R-2Ph-4PACz has a unique structure. The benzene ring and carbazole group in the molecular end group of 2Ph-4PACz or R-2Ph-4PACz are connected by a single bond. In space, the benzene ring and carbazole group present a certain angle, which makes it difficult for 2Ph-4PACz or R-2Ph-4PACz molecules to aggregate. This results in better coverage of the textured substrate 1 surface. Therefore, the material of the first hole transport layer 22 exhibits better conformability on the substrate 1 surface. Furthermore, the introduction of benzene rings or benzene rings with R groups can enhance the interaction between the first hole transport layer 22 and lead halide, thereby affecting the deposition distribution of lead halide on the surface of the first hole transport layer 22, improving the conformability of the lead halide framework layer, and thus improving the conformability and crystallinity of the perovskite layer 3, promoting the improvement of the conversion efficiency of the solar cell.

[0060] The thickness of the first hole transport layer 22 significantly affects the crystallinity and conformation of the perovskite layer 3. When the thickness of the first hole transport layer 22 is too low, the interaction between 2Ph-4PACz or R-2Ph-4PACz and lead halide is relatively weak, resulting in poor conformation coverage of the lead halide framework layer. When the thickness of the first hole transport layer 22 is too high, the series resistance of the solar cell increases, which is not conducive to improving the conversion efficiency of the solar cell.

[0061] For example, the thickness of the first hole transport layer can be 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm and 15nm, etc.

[0062] It should be noted that the textured surface is a pyramid-shaped textured surface, which can effectively enhance the absorption of light by the solar cell, reduce surface reflectivity, and increase the photocurrent density.

[0063] The electron transport layer 5 is made of any material capable of transporting electrons. This application does not limit the specific material of the electron transport layer 5. For example, the material of the electron transport layer 5 can be C. 60 And polyisobutylene dicarboxylate, etc.

[0064] For example, the structure of R-2Ph-4PACz can be:

[0065]

[0066] wait.

[0067] In some embodiments, the solar cell further includes a second hole transport layer 21, which is stacked on the side of the first hole transport layer 22 away from the perovskite layer 3. The material of the second hole transport layer 21 includes Cu2O, CuO, and MoO. x NiMgLiO and NiO x One or more of them.

[0068] Due to Cu2O, CuO, MoO x NiMgLiO and NiO x The hydroxyl groups on the surface of the second hole transport layer 21, formed from metal oxides, facilitate anchoring and bonding with the phosphate groups in 2Ph-4PACz or R-2Ph-4PACz, promoting the uniform deposition of the first hole transport layer 22 on the textured second hole transport layer 21. Using the second hole transport layer 21 formed from any of the above materials as the growth substrate 1 of the first hole transport layer 22 promotes better conformal growth of the first hole transport layer 22. Furthermore, the strong interaction between the first hole transport layer 22 and lead halide enhances the conformal effect of the perovskite layer 3, effectively increasing the open-circuit voltage and fill factor at the interface, reducing non-radiative recombination at the interface, and further improving the photoelectric conversion efficiency of the solar cell.

[0069] More preferably, the material of the second hole transport layer 21 is NiO. x NiO x The second hole transport layer 21, formed from the material of the second hole transport layer 21, has more hydroxyl groups on its surface, which interact more strongly with the phosphate groups in 2Ph-4PACz or R-2Ph-4PACz, resulting in better conformal growth of the first hole transport layer 22 on the surface of the second hole transport layer 21.

[0070] In some embodiments, the thickness of the second hole transport layer 21 is 10 nm to 20 nm.

[0071] For example, the thickness of the second hole transport layer 21 can be 10nm, 12nm, 14nm, 16nm, 18nm, and 20nm, etc.

[0072] In some embodiments, the thickness of the perovskite layer 3 is 600 nm to 900 nm, and the thickness of the lead halide framework layer is 300 nm to 600 nm.

[0073] By selecting specific materials for the first hole transport layer 22, this application can effectively maintain the conformal properties of the lead halide framework layer of the aforementioned thickness. The perovskite layer 3 formed on the lead halide framework layer also exhibits excellent conformal properties. Furthermore, controlling the thickness of the perovskite layer 3 within the aforementioned range is beneficial for obtaining better light absorption and improving the photoelectric conversion efficiency of the solar cell.

[0074] For example, the thickness of the perovskite layer 3 can be 600nm, 630nm, 660nm, 700nm, 750nm, 800nm, 850nm and 900nm, etc., and the thickness of the lead halide framework layer can be 300nm, 330nm, 360nm, 400nm, 450nm, 500nm, 550nm and 600nm, etc.

[0075] In some embodiments, the thickness of the electron transport layer 5 is 10nm to 30nm. For example, the thickness of the electron transport layer 5 can be 10nm, 15nm, 20nm, 25nm, 27nm, and 30nm, etc.

[0076] In some embodiments, the thickness of the first electrode 9 is 250 nm to 400 nm. Exemplarily, the thickness of the first electrode 9 is 250 nm, 265 nm, 280 nm, 300 nm, 340 nm, 360 nm, 380 nm, and 400 nm, etc.

[0077] The first electrode 9 is used to collect photogenerated carriers and is made of a metallic material. For example, the first electrode 9 is one of silver, copper, or zinc.

[0078] In some embodiments, the substrate 1 is a textured bottom cell 11 and a composite layer 12 stacked on the textured bottom cell 11. The solar cell also includes a transparent conductive layer 7, which is located on the side of the first electrode 9 near the substrate 1.

[0079] It should be noted that the textured bottom cell 11 can be any bottom cell with a textured surface, such as a heterojunction cell. The textured bottom cell 11 has a second electrode 111 corresponding to the first electrode 9. The second electrode 111 is made of a metallic material with good conductivity, such as silver, copper, or zinc. Like the first electrode, the second electrode 111 is used to collect photogenerated carriers, ensuring that charge can be smoothly discharged from the inside of the solar cell, thus promoting efficient operation of the solar cell. The thickness of the second electrode 111 is 150 nm to 300 nm. For example, the thickness of the second electrode 111 can be 150 nm, 180 nm, 200 nm, 210 nm, 240 nm, 260 nm, 280 nm, and 300 nm.

[0080] Preferably, the composite layer 12 and the transparent conductive layer 7 are made of indium oxide semiconductor material.

[0081] The composite layer 12 and the transparent conductive layer 7 can be made of the same or different materials. Doped indium oxide semiconductor materials include indium tin oxide, indium zinc oxide, indium cerium oxide, etc. For example, the composite layer 12 is indium tin oxide, and the transparent conductive layer 7 is indium zinc oxide.

[0082] When the material of the second hole transport layer 21 is Cu2O, CuO, MoO x NiMgLiO and NiO x When one or more of the following are present, the hydroxyl structure on the surface of the second hole transport layer 21 has a strong bonding ability with the doped indium oxide semiconductor material, which is conducive to forming a dense second hole transport layer 21 with excellent conformability on the composite layer 12, thereby improving the interface performance between the composite layer 12 and the second hole transport layer 21, and further enhancing the textured conformability of the first hole transport layer 22 and the perovskite layer 3.

[0083] Preferably, the thickness of the composite layer 12 and the transparent conductive layer 7 is 30 nm to 100 nm.

[0084] For example, the thickness of the composite layer 12 can be 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, and 100nm, etc. The thickness of the transparent conductive layer 7 can be 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, and 100nm, etc.

[0085] In addition, in some embodiments, the substrate 1 can also be any substrate with a pyramidal textured surface, such as a glass substrate.

[0086] In some embodiments, the solar cell further includes a passivation layer 4, which is stacked between the perovskite layer 3 and the electron transport layer 5; and / or,

[0087] The solar cell also includes a buffer layer 6, which is stacked between the electron transport layer 5 and the transparent conductive layer 7; and / or,

[0088] The solar cell also includes an antireflection layer 8, which is stacked on the side of the transparent conductive layer 7 facing away from the substrate 1.

[0089] For example, the material of the passivation layer 4 is LiF, and the thickness is 1nm to 2nm. For example, the thickness of the passivation layer 4 is 1nm, 1.5nm, and 2nm, etc.

[0090] The buffer layer 6 is made of SnO2 and has a thickness of 10nm to 30nm. For example, the thickness of the buffer layer 6 is 10nm, 15nm, 20nm, 25nm, 27nm and 30nm, etc. The antireflection layer 8 is made of LiF and has a thickness of 80nm to 120nm. For example, the thickness of the antireflection layer 8 is 80nm, 90nm, 95nm, 100nm, 103nm, 109nm, 116nm and 120nm, etc.

[0091] Secondly, embodiments of the present invention provide a method for preparing a solar cell.

[0092] A method for fabricating a solar cell, as mentioned in the first aspect, includes the following steps:

[0093] Provide substrate 1;

[0094] Preparation of the first hole transport layer 22:

[0095] 2Ph-4PACz or R-2Ph-4PACz is placed in a solution environment to obtain a 2Ph-4PACz solution or an R-2Ph-4PACz solution. Then, the 2Ph-4PACz solution or R-2Ph-4PACz solution is coated onto the surface of substrate 1 and subjected to a first annealing treatment to obtain a first hole transport layer 22.

[0096] Preparation of perovskite layer 3:

[0097] A lead halide framework layer is prepared on the first hole transport layer 22;

[0098] A cationic solution was coated on the lead halide framework layer, and after a second annealing treatment, a perovskite layer 3 was obtained.

[0099] An electron transport layer 5 is prepared on the perovskite layer 3;

[0100] A first electrode 9 is fabricated on the electron transport layer 5, and a second electrode 111 is fabricated on the substrate 1.

[0101] The first hole transport layer 22 is placed at the bottom of the lead halide framework layer. There is a strong interaction between lead halide and 2Ph-4PACz or R-2Ph-4PACz, which is conducive to guiding the lead halide framework layer to achieve shape-preserving growth on the surface of the first hole transport layer 22 of the textured structure. The cationic solution is coated on the surface of the lead halide framework layer, and after the second annealing treatment, the cationic solution and the lead halide framework layer react fully to obtain the perovskite layer 3 with excellent shape-preserving effect.

[0102] In some embodiments, in the preparation step of the first hole transport layer 22, the concentration of the 2Ph-4PACz solution or the R-2Ph-4PACz solution is 1 mg / mL to 1.5 mg / mL, and the method for coating the 2Ph-4PACz solution or the R-2Ph-4PACz solution is spin coating, with a spin coating speed of 3000 rpm to 5000 rpm and a spin coating time of 30 s to 50 s.

[0103] By controlling the concentration of the 2Ph-4PACz solution or the R-2Ph-4PACz solution, and in conjunction with the spin coating speed control, the thickness of the first hole transport layer 22 can be effectively controlled, thereby better influencing the deposition distribution of lead halide on the surface of the first hole transport layer 22, and thus improving the conformation effect of the perovskite layer 3.

[0104] In some embodiments, the solvent for the 2Ph-4PACz solution or the R-2Ph-4PACz solution is one or a mixture of anhydrous ethanol, isopropanol, or cyclohexane.

[0105] Anhydrous ethanol, isopropanol, or cyclohexane exhibit good solubility for 2Ph-4PACz or R-2Ph-4PACz, which facilitates their uniform dispersion, thereby promoting the formation of high-quality, uniform thin films and improving solar cell performance. Furthermore, the good volatility of anhydrous ethanol, isopropanol, or cyclohexane allows for rapid removal during film formation, reducing solvent residue and contributing to improved quality of the first hole transport layer 22 and solar cell stability.

[0106] In some embodiments, the method for fabricating a solar cell further includes: fabricating a second hole transport layer 21 between the substrate 1 and the first hole transport layer 22.

[0107] In some embodiments, the method for fabricating solar cells further includes the following steps:

[0108] A transparent conductive layer 7 is prepared on the side of the electron transport layer 5 opposite to the perovskite layer 3;

[0109] The preparation method of substrate 1 includes the following steps:

[0110] Provides 11 soft-bottomed batteries;

[0111] A composite layer 12 is prepared on the texturized bottom battery 11.

[0112] In some embodiments, a buffer layer 6 is further prepared between the electron transport layer 5 and the transparent conductive layer 7; and / or, a passivation layer 4 is further prepared between the perovskite layer 3 and the electron transport layer 5; and / or, an antireflection layer 8 is further prepared on the side of the transparent conductive layer 7 facing away from the substrate 1.

[0113] For example, the material of the passivation layer is LiF, and the thickness is 1nm to 2nm. For example, the thickness of the passivation layer is 1nm, 1.5nm, and 2nm, etc.

[0114] Thirdly, embodiments of the present invention provide a photovoltaic module.

[0115] A photovoltaic module includes a solar cell as mentioned in the first aspect or a solar cell prepared by the preparation method mentioned in the second aspect.

[0116] The technical solution of the present invention will be further described below with reference to more specific embodiments and accompanying drawings.

[0117] Example 1

[0118] This invention provides a solar cell, comprising:

[0119] Heterojunction bottom cells;

[0120] A composite layer is stacked on the surface of the heterojunction bottom cell. The composite layer is made of indium tin oxide and has a thickness of 30 nm.

[0121] A second hole transport layer is stacked on the side of the composite layer away from the heterojunction bottom cell, and the material of the second hole transport layer is NiO. x The thickness is 15nm;

[0122] A first hole transport layer is stacked on the side of the second hole transport layer away from the heterojunction bottom cell. The material of the first transport layer is 2Ph-4PACz and the thickness is 6nm.

[0123] The perovskite layer is stacked on the side of the first hole transport layer away from the heterojunction bottom cell. The perovskite layer is formed by reacting the lead iodide framework layer with a cation solution. The lead iodide framework layer has a thickness of 450 nm, and the perovskite layer has a thickness of 700 nm.

[0124] A passivation layer is stacked on the side of the perovskite layer away from the heterojunction bottom cell. The passivation layer is made of LiF and has a thickness of 1.5 nm.

[0125] An electron transport layer is stacked on the side of the passivation layer away from the heterojunction bottom cell. The material of the electron transport layer is C. 60 The thickness is 20nm;

[0126] A buffer layer is stacked on the side of the electron transport layer away from the heterojunction bottom cell. The buffer layer is made of SnO2 and has a thickness of 15nm.

[0127] A transparent conductive layer is stacked on the side of the buffer layer away from the heterojunction bottom cell. The transparent conductive layer is indium zinc oxide and has a thickness of 100 nm.

[0128] An antireflection layer is stacked on the side of the transparent conductive layer away from the heterojunction bottom cell. The antireflection layer is made of LiF and has a thickness of 100 nm.

[0129] The first electrode forms an ohmic contact with the bottom cell. The material of the first electrode is Ag, and the thickness is 200 nm.

[0130] A second electrode is formed through the antireflection layer and the transparent conductive layer to form an ohmic contact. The material of the second electrode is Ag, and the thickness is 300 nm.

[0131] The above-mentioned method for preparing solar cells includes the following steps:

[0132] Provide heterojunction base cells;

[0133] A composite layer was prepared on a heterojunction bottom cell using magnetron sputtering.

[0134] A second hole transport layer was prepared on the composite layer using physical vapor deposition.

[0135] The first hole transport layer was prepared on the second hole transport layer using a solution spin-coating method, as detailed below:

[0136] Take 0.2 mL of 2Ph-4PACz solution with a concentration of 1.3 mg / mL, spin-coat at 4000 rpm for 30 s to spin-coat the 2Ph-4PACz solution onto the surface of the second hole transport layer, and then anneal at 100℃ for 10 min to obtain the first hole transport layer.

[0137] A perovskite layer was prepared on the first hole transport layer using a two-step method, as detailed below:

[0138] Lead iodide and cesium bromide were co-deposited on the surface of the first hole transport layer at a deposition rate ratio of 5:1, resulting in a lead iodide framework layer.

[0139] A cationic solution was spin-coated onto the lead iodide framework layer. The cationic solution was prepared by dissolving FAI, FABr, MACl and MABr in 1 mL of isopropanol at a mass ratio of 50:14:10:8. The solution was then annealed at 150 °C for 20 min to obtain a perovskite layer.

[0140] A passivation layer was prepared on the perovskite layer by vapor deposition.

[0141] An electron transport layer was prepared on the passivation layer by vapor deposition.

[0142] A buffer layer was prepared on the electron transport layer using atomic layer deposition.

[0143] A transparent conductive layer was prepared on the buffer layer using magnetron sputtering.

[0144] An antireflection layer was prepared on a transparent conductive layer using a vapor deposition method.

[0145] The first and second electrodes are prepared by evaporation. The first electrode forms an ohmic contact with the heterojunction bottom cell, and the second electrode forms an ohmic contact with the second transparent electrode through the antireflection layer.

[0146] Example 2

[0147] This invention provides a solar cell that differs from Embodiment 1 in that the material of the first hole transport layer is replaced with NO2-2Ph-4PACz instead of 2Ph-4PACz, while the rest remains the same as in Embodiment 1.

[0148] Example 3

[0149] This invention provides a solar cell that differs from Embodiment 1 in that the material of the first hole transport layer is replaced by F-2Ph-4PACz instead of 2Ph-4PACz, while the rest remains the same as in Embodiment 1.

[0150] Example 4

[0151] This invention provides a solar cell that differs from Embodiment 1 in that the material of the first hole transport layer is replaced with Br-2Ph-4PACz instead of 2Ph-4PACz, while the rest remains the same as in Embodiment 1.

[0152] Example 5

[0153] This invention provides a solar cell that differs from Embodiment 1 in that the thickness of the first hole transport layer is 2nm, while the rest remains the same as in Embodiment 1.

[0154] Example 6

[0155] This invention provides a solar cell that differs from Embodiment 1 in that the thickness of the first hole transport layer is 4 nm, while the rest remains the same as in Embodiment 1.

[0156] Example 7

[0157] This invention provides a solar cell that differs from Embodiment 1 in that the thickness of the first hole transport layer is 8 nm, while the rest remains the same as in Embodiment 1.

[0158] Comparative Example 1

[0159] The present invention provides a solar cell in a comparative example. The difference between this cell and Example 1 is that the material of the first hole transport layer is replaced by 2PACz instead of 2Ph-4PACz, while the rest remains the same as in Example 1.

[0160] Comparative Example 2

[0161] The present invention provides a solar cell in a comparative example, which differs from Example 1 in that the material of the first hole transport layer is CH3-4PACz instead of 2Ph-4PACz, while the rest remains the same as in Example 1.

[0162] Comparative Example 3

[0163] The present invention provides a solar cell in a comparative example, which differs from Example 1 in that: the material of the first hole transport layer is replaced by [4-(7H-dibenzocarbazole-7-yl)butyl]phosphoric acid instead of 2Ph-4PACz, while the rest remains the same as in Example 1.

[0164] Experiment 1

[0165] 1.1 Electron Microscopy Scanning Test

[0166] The cross-sections of the perovskite layers prepared in Example 1, Comparative Example 1, and Comparative Example 2 were scanned using a scanning electron microscope. The resulting SEM images are shown below. Figure 2 , Figure 3 and Figure 4 .

[0167] Figure 2 The first hole transport layer in the middle is the 2Ph-4PACz layer. Figure 3 The first hole transport layer in the middle is the 2PACz layer. Figure 4 The first hole transport layer in the middle is the CH3-4PACz layer.

[0168] from Figure 2 , Figure 3 and Figure 4 The comparison clearly shows that the perovskite layer on the surface of the 2Ph-4PACz layer has a relatively complete pyramidal textured structure with distinct troughs and valleys, exhibiting excellent shape retention. In contrast, the pyramidal textured surfaces of the perovskite layers on the surfaces of the 2PACz and CH3-4PACz layers show collapsed troughs, resulting in poor shape retention. Therefore, compared to Comparative Example 1 and Comparative Example 2, the perovskite layer prepared in Example 1 demonstrates significantly improved shape retention.

[0169] 1.2 X-ray diffraction test

[0170] The perovskite layers of Example 1 and Comparative Example 1 were tested using X-ray diffraction, and the obtained spectra are shown below. Figure 5 .

[0171] Figure 5 In the diagram, 2Ph-4PACz-based PVK (i.e., the perovskite layer) corresponds to the X-ray diffraction result of the perovskite layer in Example 1, and 2PACz-based PVK corresponds to the X-ray diffraction result of the perovskite layer in Comparative Example 1. Figure 5 It can be seen that the perovskite main peak intensity corresponding to the 2Ph-4PACz layer is significantly improved compared to the perovskite main peak intensity of the 2PACz layer, proving that the perovskite layer in Example 1 has a higher perovskite crystal phase content and better perovskite crystallinity.

[0172] Experiment 2

[0173] Solar cell performance testing

[0174] The performance of perovskite tandem solar cells was tested using the Wavelabs solar simulator under the following conditions: AM1.5, 1000 W / m². 2 The test environment temperature was 25℃. Before testing, the light source was calibrated to simulate sunlight intensity using a standard silicon cell. Performance tests included energy conversion efficiency (%), open-circuit voltage (V), and short-circuit current (mA / cm²). 2 , fill factor, in percentage.

[0175] The test results of the above embodiments and comparative examples are shown in Table 1.

[0176] Table 1

[0177]

[0178]

[0179] Comparing the data of Example 1 and Comparative Examples 1, 2, and 3 in Table 1, it can be seen that, compared with Comparative Examples 1, 2, and 3, Example 1 has significantly improved open-circuit voltage, fill factor, and energy conversion efficiency. This proves that, compared with other self-assembled materials, the 2Ph-4PACz used in this application has excellent dispersibility and can better cover the surface of the textured substrate. Furthermore, the interaction between 2Ph-4PACz and lead iodide is more obvious, which can significantly improve the deposition distribution of the lead iodide framework layer on the textured structure surface, enhance the textured conformation and crystallinity of the perovskite layer, and thus improve the overall performance of the solar cell.

[0180] The solar cells, their preparation methods, and photovoltaic modules disclosed in the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the solar cells, their preparation methods, photovoltaic modules, and their core ideas of the present invention. 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 invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A solar cell, characterized in that, The device comprises a substrate, a first hole transport layer, a perovskite layer, an electron transport layer, and a first electrode, stacked from bottom to top. The substrate has a textured structure, and the first hole transport layer, the perovskite layer, and the electron transport layer grow along the textured structure. The thickness of the first hole transport layer is 2 nm to 15 nm, and the material of the first hole transport layer is 2Ph-4PACz or R-2Ph-4PACz. The molecular structure of 2Ph-4PACz is as follows: The structure of the R-2Ph-4PACz is as follows: R is one of NO2, F, Cl, Br, pyrazine, or pyridine; The perovskite layer is obtained by reacting a lead halide framework layer with a cation solution.

2. The solar cell according to claim 1, characterized in that, The solar cell further includes a second hole transport layer, which is stacked on the side of the first hole transport layer away from the perovskite layer. The material of the second hole transport layer includes Cu2O, CuO, and MoO. x NiMgLiO or NiO x One or more combinations thereof.

3. The solar cell according to claim 2, characterized in that, The thickness of the second hole transport layer is 10nm to 20nm.

4. The solar cell according to any one of claims 1-3, characterized in that, The thickness of the perovskite layer is 600 nm to 900 nm, the thickness of the lead halide framework layer is 300 nm to 600 nm; and / or, the thickness of the electron transport layer is 10 nm to 30 nm; and / or, the thickness of the first electrode is 250 nm to 400 nm.

5. The solar cell according to claim 1, characterized in that, The substrate includes a textured base cell and a composite layer stacked on the textured base cell. The solar cell also includes a transparent conductive layer located on the side of the first electrode near the substrate.

6. The solar cell according to claim 5, characterized in that, The solar cell further includes a passivation layer, which is stacked between the perovskite layer and the electron transport layer; and / or, The solar cell further includes a buffer layer, which is stacked between the electron transport layer and the transparent conductive layer; and / or, The solar cell also includes an anti-reflection layer, which is stacked on the side of the transparent conductive layer away from the substrate.

7. A method for fabricating a solar cell, characterized in that, The method for preparing a solar cell according to any one of claims 1-6 includes the following steps: Provide the substrate; Preparation of the first hole transport layer: The 2Ph-4PACz or the R-2Ph-4PACz is placed in a solution environment to obtain a 2Ph-4PACz solution or an R-2Ph-4PACz solution. Then, the 2Ph-4PACz solution or the R-2Ph-4PACz solution is coated onto the surface of the substrate and subjected to a first annealing treatment to obtain the first hole transport layer. Preparation of the perovskite layer: The lead halide framework layer is prepared on the first hole transport layer; The cationic solution is coated onto the lead halide framework layer, and the perovskite layer is obtained by a second annealing treatment. The electron transport layer is prepared on the perovskite layer; The first electrode is fabricated on the electron transport layer.

8. The method for preparing a solar cell according to claim 7, characterized in that, In the step of preparing the first hole transport layer, the concentration of the 2Ph-4PACz solution or the R-2Ph-4PACz solution is 1 mg / mL to 1.5 mg / mL, the method of coating the 2Ph-4PACz solution or the R-2Ph-4PACz solution is spin coating, the spin coating speed is 3000 rpm to 5000 rpm, and the spin coating time is 30 s to 50 s.

9. The method for preparing a solar cell according to claim 7, characterized in that, The solvent for the 2Ph-4PACz solution or the R-2Ph-4PACz solution is one or a mixture of anhydrous ethanol, isopropanol, or cyclohexane.

10. The method for preparing a solar cell according to claim 7, characterized in that, The method for fabricating the solar cell further includes: fabricating a second hole transport layer between the substrate and the first hole transport layer.

11. The method for preparing a solar cell according to any one of claims 7-10, characterized in that, The method for preparing the solar cell further includes the following steps: A transparent conductive layer is prepared on the side of the electron transport layer opposite to the perovskite layer; The method for preparing the substrate includes the following steps: Provides soft-bottom batteries; A composite layer is prepared on the textured bottom battery.

12. The method for preparing a solar cell according to claim 11, characterized in that, A buffer layer is further formed between the electron transport layer and the transparent conductive layer; and / or, a passivation layer is further formed between the perovskite layer and the electron transport layer; and / or, an antireflection layer is further formed on the side of the transparent conductive layer opposite to the substrate.

13. A photovoltaic module, characterized in that, This includes solar cells as described in any one of claims 1-6 or solar cells prepared by the method described in any one of claims 7-12.

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