Perovskite solar cell and preparation method thereof, laminated cell and photovoltaic module

Abstract

The application relates to the technical field of photoelectric devices, in particular to a perovskite solar cell, a preparation method thereof, a stacked cell and a photovoltaic module. The perovskite solar cell comprises a first electrode, a perovskite layer, an electron transport layer and a second electrode, the perovskite layer is located between the first electrode and the second electrode, the electron transport layer is located between the perovskite layer and the second electrode, the electron transport layer comprises a modified fullerene layer, the modified fullerene layer comprises a fullerene material and a sulfur atom located on the surface of the fullerene material, the fullerene material is connected with the sulfur atom through a C-S covalent bond; and a tin oxide layer, the tin oxide layer is located on the modified fullerene layer and is in contact with the sulfur atom. The application modifies the fullerene material through the sulfur atom, improves the interface bonding force between the fullerene layer and the tin oxide layer, reduces the proportion of Sn in the tin oxide layer, improves the electron transport efficiency, effectively passivates the defects on the surface of the perovskite layer, reduces the interface non-radiative recombination, and improves the photoelectric conversion efficiency of the perovskite solar cell. 2+ ​

Description

Technical Field

[0001] This application relates to the field of optoelectronic device technology, and in particular to perovskite solar cells and their fabrication methods, tandem cells and photovoltaic modules. Background Technology

[0002] Perovskite solar cells have become a research hotspot in the photovoltaic field due to their excellent photoelectric performance, high photoelectric conversion efficiency, simple fabrication methods, and low production costs. In perovskite solar cells, the electron transport layer is responsible for extracting and transporting photogenerated electrons and blocking holes; its properties play a decisive role in the cell's photoelectric conversion performance and stability. Currently, composite electron transport layers composed of fullerene and tin oxide (SnO2) layers combine the high electron extraction efficiency of fullerenes with the high stability and high mobility of tin oxide, making them one of the most common structural types for electron transport layers.

[0003] However, the poor interfacial bonding between the fullerene layer and the tin oxide layer leads to a decrease in the charge transport capacity between the layers. Simultaneously, the interface between the fullerene layer and the adjacent perovskite layer exhibits non-ideal contact, including energy level mismatch and carrier recombination caused by interfacial defects, which reduces the photoelectric conversion efficiency of the perovskite solar cell. Summary of the Invention

[0004] Based on this, this application provides perovskite solar cells and their fabrication methods, tandem cells, and photovoltaic modules. The perovskite solar cells provided in this application modify the fullerene material with sulfur atoms, which significantly improves the interfacial bonding force between the fullerene layer and the tin oxide layer, and reduces the Sn content in the tin oxide layer. 2+ The proportion of [something] increases electron transport efficiency and effectively passivates defects on the surface of the perovskite layer, reducing non-radiative recombination at the interface, thereby improving the photoelectric conversion efficiency of perovskite solar cells.

[0005] The first aspect of this application provides a perovskite solar cell, comprising: a first electrode, an electron transport layer, a perovskite layer, and a second electrode, wherein the perovskite is located between the first electrode and the second electrode, and the electron transport layer is located between the perovskite layer and the second electrode. The electron transport layer comprises: a modified fullerene layer, wherein the modified fullerene layer comprises a fullerene material and sulfur atoms located on the surface of the fullerene material, the fullerene material and the sulfur atoms being connected by CS covalent bonds; and a tin oxide layer, wherein the tin oxide layer is located on the modified fullerene layer and is in contact with the sulfur atoms.

[0006] In some implementations, the thickness of the modified fullerene layer is 5 nm to 30 nm.

[0007] In some embodiments, the fullerene material includes at least one of C60, C70, methyl [6,6]-phenyl-C61-butyrate, methyl [6,6]-phenyl-C71-butyrate, and indene-C60 diadduct.

[0008] In some implementations, the thickness of the tin oxide layer is 5nm-30nm.

[0009] The second aspect of this application provides a method for fabricating a perovskite solar cell, comprising the following steps: sequentially fabricating a perovskite layer on a first electrode; depositing a fullerene material on the perovskite layer; fabricating a modified fullerene layer by connecting sulfur atoms to the fullerene material via CS covalent bonds using atomic layer deposition; fabricating a tin oxide layer on the side of the modified fullerene layer opposite to the fullerene material where the sulfur atoms are located; and fabricating a second electrode on the tin oxide layer.

[0010] In some embodiments, sulfur atoms are covalently bonded to fullerene materials via CS bonds by atomic layer deposition, including the following steps: performing at least one deposition cycle in an atomic layer deposition chamber, each deposition cycle including the following steps: alternately introducing ozone and sulfur sources.

[0011] In some implementations, each deposition cycle includes: introducing ozone; introducing a first purge gas; introducing a sulfur source; introducing a second purge gas; and the number of deposition cycles is 1 to 10.

[0012] In some embodiments, the method for preparing perovskite solar cells satisfies at least one of the following conditions: (1) the flow rate of ozone introduced each time is 100 sccm-1000 sccm; (2) the time of ozone introduction each time is 50 ms-500 ms; (3) the flow rate of sulfur source introduced each time is 100 sccm-1000 sccm; (4) the time of sulfur source introduction each time is 50 ms-500 ms.

[0013] A third aspect of this application provides a tandem solar cell, including a top cell and a bottom cell, wherein the top cell includes the perovskite solar cell described above or a perovskite solar cell prepared by the above-described method for preparing perovskite solar cells.

[0014] A fourth aspect of this application provides a photovoltaic module, including the above-described perovskite solar cell, the perovskite solar cell prepared by the above-described method for preparing perovskite solar cells, or the above-described tandem cell.

[0015] Compared with traditional technologies, this application has the following beneficial effects: The perovskite solar cell provided by this application modifies the fullerene material with sulfur atoms. The sulfur atoms are connected to the surface of the fullerene material through CS covalent bonds. This not only maintains the excellent electron transport performance of the bulk phase of the modified fullerene layer, but also endows the surface of the modified fullerene layer with multiple functions: Firstly, the sulfur atoms introduced on the surface of the modified fullerene layer provide abundant nucleation sites for the subsequent deposition of the tin oxide layer, inducing SnO2 to grow rapidly and uniformly in a layered mode, forming a dense and continuous tin oxide layer, which significantly enhances the interfacial bonding force between the modified fullerene layer and the tin oxide layer, and improves the charge transport capacity between the film layers.

[0016] Secondly, sulfur atoms bonded to the surface of the modified fullerene layer improve the band arrangement at the modified fullerene / perovskite layer interface, enhance charge extraction at the interface, optimize the energy level matching at the modified fullerene / perovskite layer interface, and significantly reduce non-radiative recombination loss at the interface, which is beneficial to improving the photoelectric conversion efficiency of perovskite solar cells. Attached Figure Description

[0017] To better describe and illustrate embodiments or examples of the applications disclosed herein, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the embodiments or examples currently described, or the best mode of conduct of these applications as currently understood. Furthermore, throughout the drawings, the same reference numerals denote the same parts.

[0018] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell in one embodiment of this application.

[0019] Figure 2 This is a schematic flowchart of a method for fabricating a perovskite solar cell according to one embodiment of this application.

[0020] Figure 3 The images show the Fourier transform infrared spectra of the fullerene material deposited on the surface of the perovskite layer before and after modification in Example 1 of this application.

[0021] Figure reference numerals: 10, perovskite solar cell; 101, transparent conductive electrode; 102, hole transport layer; 103, perovskite layer; 104, electron transport layer; 1041, modified fullerene layer; 1042, tin oxide layer; 105, metal electrode. Detailed Implementation

[0022] Reference will now be made to detailed embodiments of this application, one or more of which are described below. Each example is provided for explanation and not for limitation of this application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0023] Therefore, this application is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of this application are disclosed in or will be apparent from the following detailed description. It will be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this application.

[0024] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0025] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0026] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0027] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0028] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0029] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0030] In this application, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0031] In this application, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0032] like Figure 1 As shown, a first aspect of this application provides a perovskite solar cell 10, including a first electrode, a perovskite layer 103, an electron transport layer 104, and a second electrode. The perovskite layer 103 is located between the first electrode and the second electrode, and the electron transport layer 104 is located between the perovskite layer 103 and the second electrode. The electron transport layer 104 includes: a modified fullerene layer 1041, which includes a fullerene material and sulfur atoms located on the surface of the fullerene material, and the fullerene material and the sulfur atoms are connected by CS covalent bonds; and a tin oxide layer 1042, which is located on the modified fullerene layer 1041 and is in contact with the sulfur atoms.

[0033] The perovskite solar cell 10 provided in this application modifies the fullerene material with sulfur atoms. The sulfur atoms are covalently connected to the surface of the fullerene material through CS bonds. This not only maintains the excellent electron transport performance of the bulk phase of the modified fullerene layer 1041, but also endows the surface of the modified fullerene layer 1041 with multiple functions: Firstly, the sulfur atoms introduced on the surface of the modified fullerene layer 1041 provide abundant nucleation sites for the subsequent deposition of the tin oxide layer 1042, inducing SnO2 to grow rapidly and uniformly in a layered mode, forming a dense and continuous tin oxide layer 1042. This significantly enhances the interfacial bonding force between the modified fullerene layer 1041 and the tin oxide layer 1042, and improves the charge transport capability between the film layers.

[0034] Secondly, sulfur atoms are bonded to the surface of the modified fullerene layer 1041, which improves the band arrangement of the modified fullerene layer 1041 / perovskite layer 103 interface, enhances the charge extraction at the interface, optimizes the energy level matching of the modified fullerene layer 1041 / perovskite layer 103 interface, significantly reduces the nonradiative recombination loss at the interface, and is conducive to improving the photoelectric conversion efficiency of the perovskite solar cell 10.

[0035] In some embodiments, the thickness of the modified fullerene layer 1041 in the perovskite solar cell 10 is 5 nm to 30 nm.

[0036] Optionally, the thickness of the modified fullerene layer 1041 is 5 nm, 10 nm, 15 nm, 20 nm, 25 nm or 30 nm, or the thickness of the modified fullerene layer 1041 can be within any two of the above thicknesses.

[0037] Within the thickness range of the modified fullerene layer 1041, the film is ensured to be continuous and dense to support sulfur modification.

[0038] In some embodiments, the thickness of the modified fullerene layer 1041 in the perovskite solar cell 10 is 10 nm to 30 nm.

[0039] In some embodiments, the fullerene material includes at least one of C60, C70, methyl [6,6]-phenyl-C61-butyrate, methyl [6,6]-phenyl-C71-butyrate, and indene-C60 diadduct.

[0040] In some embodiments, the thickness of the tin oxide layer 1042 in the perovskite solar cell 10 is 5 nm to 30 nm.

[0041] In some embodiments, in the perovskite solar cell 10, at least one of the first electrode and the second electrode is a transparent conductive electrode 101.

[0042] In some embodiments, in the perovskite solar cell 10, one of the first electrode and the second electrode is a transparent conductive electrode 101, and the other is one or more of a transparent conductive electrode 101 and a metal electrode 105.

[0043] Optionally, the metal electrode 105 includes one or more of silver (Ag) and copper (Cu).

[0044] Optionally, the transparent conductive electrode 101 includes one or more of indium tin oxide (ITO), indium zinc oxide (IZO), tungsten-doped indium oxide (IWO), and aluminum-doped zinc oxide (AZO).

[0045] In some embodiments, the perovskite solar cell 10 further includes a hole transport layer 102 disposed between the first electrode and the perovskite layer 103.

[0046] Understandably, the perovskite solar cell 10 includes a standard (upright) perovskite solar cell 10 and an inverted (reverse) perovskite solar cell 10. Exemplarily, the standard perovskite solar cell 10 includes, from bottom to top, a transparent conductive electrode 101, an electron transport layer 104, a perovskite layer 103, a hole transport layer 102, and a metal electrode 105; the inverted perovskite solar cell 10 replaces the positions of the hole transport layer 102 and the electron transport layer 104, and its structure typically includes, from bottom to top, a transparent conductive electrode 101, a hole transport layer 102, a perovskite layer 103, an electron transport layer 104, and a metal electrode 105.

[0047] In some embodiments, the first electrode of the perovskite solar cell 10 is a transparent conductive electrode 101, and the second electrode is a metal electrode 105. In this case, the perovskite solar cell 10 is an inverted perovskite solar cell 10.

[0048] See Figure 1 In some embodiments, the solar cell is an inverted perovskite solar cell 10, which includes a transparent conductive electrode 101, a hole transport layer 102, a perovskite layer 103, an electron transport layer 104 and a metal electrode 105 stacked sequentially.

[0049] In some embodiments, in the perovskite solar cell 10, the perovskite layer 103 is made of ABX3, where A ions are monovalent cations, including Cs. + K + 、Rb + One or more of monovalent amine cations and monovalent amido cations. Non-limiting examples of monovalent amine cations include CH3NH3. + (Methylamine, MA) + ), ammonium (NH4) + Non-limiting examples of monovalent amidine cations include NH₂CH=NH₂. + (Formamidin, FA) + B ions are divalent cations, including Pb. 2+ Sn 2+ Fe 2+ Mn 2+ Ni 2+ 、Ge 2+ Co 2+ and Sb 2+ One or more of the following. X monovalent anions, including I... - ,Br - Cl - and SCN- One or more of them.

[0050] It should be understood that those skilled in the art can make corresponding adjustments to the content of each part of the above-mentioned compound according to actual needs, and this embodiment does not impose specific limitations in this regard.

[0051] In some embodiments, the B ion includes Pb. 2+ X ions include I - .

[0052] This application improves the band structure at the 1041 / 103 perovskite interface by bonding sulfur atoms to the surface of fullerene materials, enhances charge extraction at the interface, optimizes the energy level matching at the 1041 / 103 perovskite interface, and significantly passivates the insufficiently coordinated Pb on the perovskite surface. 2+ Ion and iodine vacancy defects reduce interfacial nonradiative recombination losses, which is beneficial to improving the photoelectric conversion efficiency of perovskite solar cells.

[0053] In some embodiments, the B ion includes Pb. 2+ and including Sn 2+ Fe 2+ Mn 2+ Ni 2+ 、Ge 2+ Co 2+ and Sb 2+ One or more of them.

[0054] In some implementations, X includes I - , and including Br - and Cl - One or more of them.

[0055] In some embodiments, the thickness of the perovskite layer 103 is 400 nm to 700 nm.

[0056] In some embodiments, the hole transport layer 102 is composed of one or more of the following: self-assembled monomolecular material, polyethylene terephthalate (PTAA), 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Sprio-OMeTAD), a polymer of 3-hexylthiophene (P3HT), mixed conductor poly(3,4-ethylenedioxythiophene)poly(styrene sulfonate) (PEDOT:PSS), 2,2',7,7'-tetratetra(di-p-tolylamino)spiro-9,9'-difluorene (Spiro-TTB), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4-TCNQ), 2,2'-(perfluoronaphthalene-2,6-dimethylene)dimalonitrile (F6TCNNQ), and nickel oxide (NiOx).

[0057] Optionally, the self-assembled monomolecular materials include [2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl]phosphonic acid, (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid, (4-(7H-dibenzocarbazole-7-yl)butyl)phosphonic acid, [2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [4-(9H-carbazole-9-yl)butyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid, [4-(3,6-dimethoxy-9H-carbazole-9-yl]ethyl]phosphonic acid, [4-(3,6-dimethoxy-9H-carbazole-9-yl]ethyl]phosphonic acid, [4-(3,6-dimethoxy-9H-carbazole-9-yl]ethyl]phosphonic acid, [4-(3,6-dimethoxy-9H-carbazole-9-yl) ... [2-(3,6-dibromo-9H-carbazole-9-yl)ethyl]phosphonic acid, [4-(3,6-dibromo-9H-carbazole-9-yl)butyl]phosphonic acid, [4-(3,6-diphenyl-9H-carbazole-9-yl)hexyl]phosphonic acid, [2-(7H-dibenzocarbazole-7-yl)ethyl]phosphonic acid, (4-(2,7-dibromo-9,9-dimethylacridin-10(9H)yl)butyl)phosphonic acid, and [4-(3,7-dibromo-10H-phenthiazin-10-yl)butyl]phosphonic acid.

[0058] In some implementations, the hole transport layer 102 has a thickness of 5 nm to 20 nm.

[0059] Furthermore, during the fabrication of the perovskite solar cell 10, researchers attempted various traditional doping techniques, including wet chemical methods, high-temperature solid-state heat treatment, and thermal evaporation co-evaporation, to study how to stably and uniformly introduce sulfur into the fullerene layer. However, these methods all failed to achieve stable, controllable, and uniform sulfur introduction into the fullerene layer.

[0060] Specifically, wet chemical methods: the reaction path is uncontrollable, sulfur exists mainly in the form of physical adsorption or charge transfer complexes, and solvent and byproduct residues are easily left, introducing impurities. High-temperature solid-state heat treatment: it is difficult to achieve effective doping and easily leads to the decomposition of the perovskite layer. Thermal evaporation and co-evaporation: sulfur grows in islands on the fullerene surface, resulting in non-uniform deposition, and the sulfur atoms are bonded to the fullerene layer by van der Waals forces. In subsequent processes (such as ALD deposition of SnO2) or during device operation, sulfur is easily detached or migrated. At the same time, the thermal evaporation process easily leads to the aggregation of fullerene molecules.

[0061] Based on this, such as Figure 2 As shown, the second aspect of this application provides a method for preparing a perovskite solar cell 10, comprising the following steps: S10, preparing a perovskite layer 103 on a first electrode.

[0062] S20. Deposit fullerene material on perovskite layer 103.

[0063] S30. A modified fullerene layer 1041 is prepared by connecting sulfur atoms to fullerene materials via CS covalent bonds using atomic layer deposition.

[0064] S40. Prepare a tin oxide layer 1042 on the side of the modified fullerene layer 1041 where the sulfur atoms are away from the fullerene material.

[0065] And S50, a second electrode is prepared on the tin oxide layer 1042.

[0066] This application describes sulfur modification on the surface of the fullerene layer away from the perovskite layer 103 using atomic layer deposition. This allows sulfur atoms to be stably bonded to the fullerene material surface through CS covalent bonds, forming a uniform and controllable sulfur doping. This avoids local agglomeration, has good doping repeatability, and overcomes the technical problems of instability and non-uniformity of traditional methods.

[0067] Meanwhile, the CS covalent bond structure helps to suppress sulfur shedding, oxidation and degradation, effectively maintaining the stability of interface functions; and significantly enhances the interfacial bonding force between the modified fullerene layer 1041 and the tin oxide layer 1042, thereby extending the device lifespan.

[0068] In addition, the energy level matching of the modified fullerene layer 1041 / perovskite layer 103 interface was optimized, which significantly reduced the nonradiative recombination loss at the interface.

[0069] In some embodiments, sulfur atoms are covalently bonded to fullerene materials via CS bonds by atomic layer deposition, including the following steps: performing at least one deposition cycle in an atomic layer deposition chamber, each deposition cycle including the following steps: alternately introducing ozone and sulfur sources.

[0070] In some implementations, ozone is generated by an ozone generator with a generation power of 1%-100%.

[0071] In some embodiments, the sulfur source includes at least one of hydrogen sulfide (H2S) and tert-butyl mercaptan.

[0072] Furthermore, hydrogen sulfide is used as the sulfur source. Using hydrogen sulfide as the sulfur source for sulfur modification of the fullerene layer results in a single decomposition product that is easy to remove.

[0073] Optionally, hydrogen sulfide is a water source or gas containing hydrogen sulfide.

[0074] In this application, the modification of sulfur atoms on the surface of the fullerene layer is achieved through atomic layer deposition (ALD) process. The reaction mechanism is as follows (taking hydrogen sulfide as the sulfur source as an example): The atomic layer deposition process includes the first half-reaction: the introduced ozone (O3) attacks the carbon-carbon double bond (C=C) cage on the surface of the fullerene material molecule to form epoxy group (COC); the second half-reaction: the active sites provided by COC are more likely to react with the subsequently introduced hydrogen sulfide (H2S). The SH bond in H2S breaks and forms CS covalent bond with the carbon site, while releasing water molecules (H2O).

[0075] The first half of the reaction can be simplified as: C + O3 → CO (activation).

[0076] The second half of the reaction can be simplified as: CO + H2S → CS + H2O.

[0077] The reaction can be completed at a relatively low ALD process temperature. Sulfur atoms are stably anchored to the surface of the fullerene material through CS covalent bonds, forming a uniform and controllable sulfur doping. This application achieves controllable, uniform, and covalent bonding of sulfur atoms on the surface of the fullerene material through a two-step reaction of selective activation of the fullerene surface by O3 and nucleophilic ring-opening grafting by H2S, avoiding problems such as uneven sulfur distribution and weak bonding force in traditional methods.

[0078] In some implementations, each deposition cycle includes: introducing ozone; introducing a first purge gas; introducing a sulfur source; and introducing a second purge gas.

[0079] In some embodiments, the first purge gas and the second purge gas are each independently an inert gas. It is understood that the inert gas includes, but is not limited to, at least one of nitrogen and argon.

[0080] In some implementations, the number of cycles is 1 to 10. Optionally, the number of cycles is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. Further, the number of cycles is 3 to 7.

[0081] Within the range of the above-mentioned number of cycles, it is beneficial to form uniform and controllable sulfur doping on the surface of fullerene materials; ensure the stable formation of CS covalent bonds and avoid physical adsorption or agglomeration; and provide abundant nucleation sites for the subsequent formation of tin oxide.

[0082] In some embodiments, in the method for fabricating the perovskite solar cell 10, the flow rate of ozone introduced each time is 100 sccm-1000 sccm. Optionally, the flow rate of ozone introduced each time is 100 sccm, 200 sccm, 300 sccm, 400 sccm, 500 sccm, 600 sccm, 700 sccm, 800 sccm, 900 sccm, or 1000 sccm, or the flow rate of ozone introduced each time may be within the range of any two of the above flow rates.

[0083] In some embodiments, the ozone introduction time in the fabrication method of the perovskite solar cell 10 is 50ms-500ms each time. Optionally, the ozone introduction time each time is 50ms, 100ms, 200ms, 300ms, 400ms, or 500ms, or the ozone introduction time each time may be within any two of the above-mentioned time ranges.

[0084] If the ozone flow rate is too low or the ozone introduction time is too short, the number of epoxy groups generated on the surface of the fullerene material will be insufficient, resulting in low coverage of subsequent sulfur modification, insignificant interface modification effect, and no significant improvement in film adhesion. If the ozone flow rate is too high or the ozone introduction time is too long, it is easy to cause excessive oxidation or even damage to the cage structure of the fullerene material, introducing unexpected defects. Although the film adhesion is improved, the performance of the perovskite solar cell 10 is reduced. Therefore, the ozone flow rate and introduction time are controlled within the above range to ensure the number of active sites (mainly epoxy groups) while avoiding excessive oxidation that damages the cage structure of the fullerene material.

[0085] In some embodiments, in the method for fabricating the perovskite solar cell 10, the flow rate of the sulfur source introduced each time is 100 sccm-1000 sccm. Optionally, the flow rate of the sulfur source introduced each time is 100 sccm, 200 sccm, 300 sccm, 400 sccm, 500 sccm, 600 sccm, 700 sccm, 800 sccm, 900 sccm, or 1000 sccm, or the flow rate of the sulfur source introduced each time may be within the range of any two of the above flow rates.

[0086] In some embodiments, the time for introducing the sulfur source each time in the fabrication method of the perovskite solar cell 10 is 50ms-500ms. Optionally, the time for introducing the sulfur source each time is 50ms, 100ms, 200ms, 300ms, 400ms, or 500ms, or the time for introducing the sulfur source each time can be within any two of the above-mentioned times.

[0087] If the sulfur source flow rate is too low or the sulfur source introduction time is too short, the epoxy ring-opening reaction will be incomplete, resulting in low surface thiol modification density and no significant improvement in film adhesion. Conversely, if the sulfur source flow rate is too high or the sulfur source introduction time is too long, unintended sulfur-containing species aggregates are easily formed on the fullerene material surface, contaminating the interface and undermining the self-limiting property of the atomic layer deposition process, thus reducing film adhesion. Therefore, the sulfur source flow rate and introduction time should be controlled within the above-mentioned ranges to ensure that the epoxy ring-opening reaction proceeds fully.

[0088] In some implementations, the temperature for atomic layer deposition is 25°C to 120°C.

[0089] Optionally, the temperature for atomic layer deposition is 25°C, 40°C, 55°C, 75°C, 100°C, or 120°C, or the temperature for atomic layer deposition can be within any two of the above temperatures.

[0090] The atomic layer deposition temperature of this application is relatively low, which can achieve sulfur modification on the surface of fullerene material at low temperature and reduce thermal damage to the perovskite layer 103 and the first electrode.

[0091] In some embodiments, the step of preparing a tin oxide layer 1042 on the side of the modified fullerene layer 1041 where the sulfur atoms are away from the fullerene material includes: S100, introducing a tin source.

[0092] S200, purging is performed using an inert gas as the third purging gas.

[0093] S300, oxygen source introduced.

[0094] S400, purging is performed using an inert gas as the fourth purging gas.

[0095] Steps S100 to S400 constitute one cycle, and multiple cycles are repeated to form a tin oxide layer 1042 on the surface of the modified fullerene layer 1041.

[0096] It is understood that this application does not limit the order in which the sulfur-oxygen source and the tin source are introduced. Because in the early stages of atomic layer deposition, film growth follows an island-like nucleation mechanism, the precursor preferentially forms nanoclusters at local adsorption sites, which then connect and grow into a continuous film. Therefore, even if the oxygen source is introduced first, followed by the tin source, the technical solution of this application can still be achieved.

[0097] Understandably, this application does not specifically limit the types of oxygen and tin sources, and commonly used oxygen and tin sources in the art can be used. The following examples are merely illustrative: oxygen sources include, but are not limited to, water; tin sources include, but are not limited to, tetra(dimethylamino)tin (TDMASn, C8H). 24 N4Sn).

[0098] In some implementations, the flow rate of the tin source is 100 sccm to 1000 sccm. Optionally, the flow rate of the tin source each time is 100 sccm, 200 sccm, 300 sccm, 400 sccm, 500 sccm, 600 sccm, 700 sccm, 800 sccm, 900 sccm, or 1000 sccm, or the flow rate of the tin source each time may be within the range of any two of the above flow rates.

[0099] In some implementations, the solder source is introduced for a period of 50ms-500ms. Optionally, the solder source is introduced for a period of 50ms, 100ms, 200ms, 300ms, 400ms, or 500ms each time, or the solder source is introduced for a period of any two of the above times.

[0100] In some embodiments, the flow rate of the oxygen source is 100 sccm-1000 sccm. Optionally, the flow rate of the oxygen source introduced each time is 100 sccm, 200 sccm, 300 sccm, 400 sccm, 500 sccm, 600 sccm, 700 sccm, 800 sccm, 900 sccm, or 1000 sccm, or the flow rate of the oxygen source introduced each time may be within the range of any two of the above flow rates.

[0101] In some implementations, the oxygen source is introduced for a period of 50ms-500ms. Optionally, the oxygen source is introduced for a period of 50ms, 100ms, 200ms, 300ms, 400ms, or 500ms each time, or the oxygen source is introduced for a period of any two of the above times.

[0102] In some embodiments, the flow rate of the inert gas used as the third purge gas is 100 sccm-1000 sccm. Optionally, the purge flow rate can be 100 sccm, 200 sccm, 300 sccm, 400 sccm, 500 sccm, 600 sccm, 700 sccm, 800 sccm, 900 sccm, or 1000 sccm, or the purge flow rate can be within any two of the above flow rates.

[0103] In some embodiments, the purging time using an inert gas as the fourth purging gas is 5s-60s. Optionally, the purging time is 5s, 10s, 15s, 20s, 25s, 30s, 40s, 50s, or 60s, or the purging time may be within any two of the above times.

[0104] In some embodiments, the number of cycles is between 10 and 200. Optionally, the number of cycles can be 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, or 200, or the number of cycles can be within any two of the above ranges. Thus, by controlling the number of cycles, the thickness of the prepared tin oxide layer 1042 is controlled.

[0105] In some embodiments, the inert gas includes at least one of nitrogen and argon.

[0106] In some embodiments, the method for preparing solar energy further includes the following step: preparing a hole transport layer 102 on the side of the first electrode near the perovskite layer 103.

[0107] Specifically, as an example, the perovskite solar cell 10 is an inverted perovskite solar cell 10, and its fabrication method includes the following steps: cleaning and drying the transparent conductive electrode 101; fabricating a hole transport layer 102 on the transparent conductive electrode 101; fabricating a perovskite layer 103 on the hole transport layer 102; depositing an electron transport layer 104 on the perovskite layer 103; and fabricating a metal electrode 105 on the electron transport layer 104.

[0108] Understandably, when the perovskite solar cell 10 is a formal perovskite solar cell 10, its preparation sequence is slightly different, and adaptive adjustments can be made according to the specific structure.

[0109] It should be noted that the preparation methods of the first electrode, hole transport layer 102, perovskite layer 103 and second electrode are not particularly limited in this application. They can be prepared by commonly used methods in the art, including but not limited to solution methods and solid deposition methods. Solution methods include any one of spin coating, spray coating, blade coating and slot coating. Solid deposition methods include any one of vacuum evaporation, sputtering deposition and plasma deposition.

[0110] A third aspect of this application provides a tandem solar cell, including a top cell and a bottom cell. The top cell includes the perovskite solar cell 10 described above or the perovskite solar cell 10 prepared by the above method. The bottom cell includes a crystalline silicon cell.

[0111] It is understood that tandem solar cells include, but are not limited to, two-terminal tandem solar cells, three-terminal tandem solar cells, and four-terminal tandem solar cells. Further, tandem solar cells include, but are not limited to, perovskite solar cells stacked with crystalline silicon cells, perovskite solar cells stacked with perovskite solar cells, and perovskite solar cells stacked with thin-film cells. Thin-film cells include, but are not limited to, perovskite solar thin-film cells, copper indium selenide solar thin-film cells, gallium arsenide solar thin-film cells, and cadmium sulfide solar thin-film cells; crystalline silicon cells include, but are not limited to, PERC cells (passivated emitter and back contact cells), IBC cells (interdigitated back contact cells), TOPCon cells (tunneling oxide passivated contact cells), HJT cells (heterojunction cells), and HBC cells (back contact heterojunction cells).

[0112] The advantages of the perovskite solar cell 10 in any of the above embodiments are also present in this tandem cell, and will not be repeated here.

[0113] The fourth aspect of this application provides a photovoltaic module, including the perovskite solar cell 10 described above, the perovskite solar cell 10 prepared by the method described above, or the tandem cell described above.

[0114] In some embodiments, the photovoltaic module includes a cell string, an encapsulating film, and a cover plate. The cell string is formed by electrically connecting multiple perovskite solar cells 10 described above, or by electrically connecting multiple tandem cells described above; the encapsulating film is used to cover the surface of the cell string; and the cover plate is used to cover the surface of the encapsulating film facing away from the cell string.

[0115] Optionally, the perovskite solar cell 10 or the tandem cell can be electrically connected in a single piece or in multiple pieces to form multiple cell strings, which are electrically connected in series and / or parallel. Further, the multiple cell strings are electrically connected to each other via conductive strips.

[0116] Optionally, the encapsulating film can be an organic encapsulating film such as ethylene-vinyl acetate copolymer film, polyethylene octene co-elastomer film, or polyethylene terephthalate film. The cover can be a glass cover, a plastic cover, or other cover with light transmission function.

[0117] The photovoltaic module also possesses the advantages of the perovskite solar cell 10 or tandem cell in any of the above embodiments, and will not be repeated here.

[0118] Based on the same inventive concept, one embodiment of this application also provides a photovoltaic system, including the photovoltaic module in any of the above embodiments.

[0119] It is understandable that photovoltaic (PV) systems can be applied to PV power plants, such as ground-mounted, rooftop, and floating power plants, as well as to equipment or devices that utilize solar energy for power generation, such as user-installed solar power supplies, solar streetlights, solar-powered cars, and solar-powered buildings. Of course, it is also understandable that the application scenarios of PV systems are not limited to these; that is, PV systems can be applied in all areas that require solar energy for power generation. Taking a PV power grid as an example, a PV system can include PV arrays, combiner boxes, and inverters. A PV array can be a combination of multiple PV modules; for example, multiple PV modules can form multiple PV arrays. The PV arrays are connected to combiner boxes, which collect the current generated by the PV arrays. The collected current then flows through an inverter, converting it into AC power required by the mains grid before being connected to the mains grid to achieve solar power supply.

[0120] The following detailed embodiments illustrate this application in more detail. It should also be understood that the following embodiments are for further explanation only and should not be construed as limiting the scope of protection of this application. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of this application fall within the scope of protection of this application. The specific process parameters, etc., in the following embodiments are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not necessarily limited to the specific values ​​in the embodiments below.

[0121] Example 1

[0122] (1) The ITO transparent conductive electrode was ultrasonically cleaned with water, acetone and ethanol in sequence for 15 min; then the residual solvent on the surface of the transparent conductive electrode was dried with an N2 air gun.

[0123] (2) A 10 nm MeO-4PACz hole transport layer was prepared on an ITO transparent conductive electrode by spin coating.

[0124] (3) 500 nm Cs was prepared on the hole transport layer by spin coating. 0.2 FA 0.8 Pb(I 0.6 Br 0.4 )3. Perovskite layer, to obtain an intermediate component consisting of ITO transparent conductive electrode / hole transport layer / perovskite layer.

[0125] (4) Using a vapor deposition equipment, add an appropriate amount of C60 to the equipment crucible, place the above intermediate parts in the vapor deposition equipment, and evacuate to 2×10⁻⁶. -4Pa; After preheating, the evaporation rate of C60 is controlled at 0.1 Å / s, while the main baffle of the evaporation equipment is turned on and the substrate is rotated to deposit 20 nm of fullerene material on the surface of the perovskite layer; after deposition, the main baffle of the evaporation equipment is turned off, the substrate rotation is stopped, and the substrate is cooled and removed.

[0126] (5) Modification: The workpiece with deposited fullerene material is sent into the atomic layer deposition (ALD) chamber, vacuum is drawn, and deposition begins at 100℃ and 2 torr. One deposition cycle is as follows: first, ozone is introduced at a flow rate of 200 sccm (nitrogen as carrier gas) for 50 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 200 sccm for 10 s; then, H2S gas is introduced at a flow rate of 200 sccm for 150 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 200 sccm for 10 s. A total of 5 deposition cycles are performed. Sulfur atoms are connected on the fullerene material through CS covalent bonds to form a modified fullerene layer. The thickness of the modified fullerene layer is basically consistent with the thickness of the fullerene material deposited on the surface of the perovskite layer.

[0127] (6) The workpiece with the modified fullerene layer prepared is placed in the atomic layer deposition chamber and deposition begins at 100°C and 2 torr. One deposition cycle is as follows: first, TDMASn is introduced at a flow rate of 300 sccm (nitrogen as carrier gas) for 100 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 300 sccm for 20 s; then, H2S gas is introduced at a flow rate of 300 sccm for 70 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 300 sccm for 20 s. A total of 150 cycles are performed to prepare a 20 nm thick tin oxide layer on the modified fullerene layer.

[0128] (7) An Ag electrode of 150 nm was prepared on the tin oxide layer by vapor deposition. An inverse perovskite solar cell was obtained.

[0129] like Figure 3 As shown, Figure 3 The images show the Fourier transform infrared spectra of the fullerene material deposited on the surface of the perovskite layer before and after modification in this embodiment. Figure 3 In the diagram, the horizontal axis represents the wavenumber, and the unit is cm. -1 The vertical axis represents absorbance, measured in au. The curve for the unmodified fullerene material layer (C60) shows only the characteristic peak of the C=C bond, corresponding to the sp... 2 Carbon skeletal vibrations; the curves of the modified fullerene material layer show the addition of a characteristic peak of the CS bond while retaining the C=C peak, indicating that CS covalent bonds were successfully formed on the C60 surface through atomic layer deposition (ALD) and H2S / O3 cyclic treatment.

[0130] Example 2

[0131] The preparation methods of this embodiment and Example 1 are basically the same, except that: in step (5), one deposition cycle is as follows: first, ozone is introduced at a flow rate of 500 sccm (nitrogen as carrier gas) for 150 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 500 sccm for 10 s; then, H2S gas is introduced at a flow rate of 500 sccm for 100 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 500 sccm for 10 s, and a total of one deposition cycle is performed.

[0132] Example 3

[0133] The preparation methods of this embodiment and Example 1 are basically the same, except that: in step (5), one deposition cycle is as follows: first, ozone is introduced at a flow rate of 100 sccm (nitrogen as carrier gas) for 50 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 100 sccm for 10 s; then, H2S gas is introduced at a flow rate of 100 sccm for 100 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 100 sccm for 10 s, and a total of one deposition cycle is performed.

[0134] Example 4

[0135] The preparation methods of this embodiment and Example 1 are basically the same, except that: in step (5), one deposition cycle is as follows: first, ozone is introduced at a flow rate of 200 sccm (nitrogen as carrier gas) for 50 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 200 sccm for 10 s; then, H2S gas is introduced at a flow rate of 200 sccm for 50 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 200 sccm for 10 s, and a total of 5 deposition cycles are performed.

[0136] Example 5

[0137] The preparation methods of this embodiment and Example 1 are basically the same, except that: in step (5), one deposition cycle is as follows: first, ozone is introduced at a flow rate of 200 sccm (nitrogen as carrier gas) for 50 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 200 sccm for 10 s; then, H2S gas is introduced at a flow rate of 200 sccm for 250 ms; then, nitrogen is used as the purge gas and purged at a flow rate of 200 sccm for 10 s, and a total of 5 deposition cycles are performed.

[0138] Example 6

[0139] The preparation methods of this embodiment and Example 1 are basically the same, except that in step (5), the deposition cycle is 10 times.

[0140] Example 7

[0141] The preparation methods of this embodiment and Example 1 are basically the same, except that: in step (4), a 5 nm fullerene material is deposited on the surface of the perovskite layer; and in step (5), the thickness of the modified fullerene layer is 5 nm.

[0142] Example 8

[0143] The preparation methods of this embodiment and Example 1 are basically the same, except that: in step (4), a 30 nm fullerene material is deposited on the surface of the perovskite layer; and in step (5), the thickness of the modified fullerene layer is 30 nm.

[0144] Example 9

[0145] The preparation method of this embodiment is basically the same as that of Example 1, except that ozone is not introduced in step (5), only H2S gas is introduced. Specifically: the workpiece with deposited fullerene material is sent into the atomic layer deposition (ALD) chamber, vacuum is drawn, and deposition begins at 100°C and 2 torr. H2S gas is introduced at a flow rate of 200 sccm for 150 ms; then nitrogen is used as the purge gas and purged at a flow rate of 200 sccm for 10 s. A total of 5 deposition cycles are performed.

[0146] The important parameters of Examples 1-9 are summarized in Table 1 below.

[0147] Table 1

[0148]

[0149] Comparative Example 1

[0150] The preparation methods of this comparative example and Example 1 are basically the same, except that step (5) was not performed, that is, sulfur atoms were not attached to the surface of the fullerene material.

[0151] Comparative Example 2

[0152] The preparation methods of this comparative example and Example 7 are basically the same, except that step (5) was not performed, that is, sulfur atoms were not attached to the surface of the fullerene material.

[0153] Comparative Example 3

[0154] The preparation methods of this comparative example and Example 8 are basically the same, except that step (5) was not performed, that is, sulfur atoms were not attached to the surface of the fullerene material.

[0155] Comparative Example 4

[0156] The preparation methods of this comparative example and Example 1 are basically the same, except that steps (4)-(5) are replaced with: using a vapor deposition equipment, adding an appropriate amount of C60 to one equipment crucible, adding an appropriate amount of sulfur powder to another equipment crucible, and placing the above intermediates in the vapor deposition equipment, and evacuating to 2×10 -4 Pa; preheat the two evaporation sources to near the evaporation temperature of the materials, control the evaporation rate of C60 at 0.1 Å / s and the evaporation rate of sulfur powder at 0.1 Å / s, and after the evaporation rates of the two materials stabilize, open the baffles of the two evaporation sources at the same time to start co-evaporation, depositing a 1 nm sulfur-doped fullerene layer on the surface of the perovskite layer; after the deposition is completed, close the main baffle of the evaporation equipment, stop rotating the substrate, and cool it down before taking it out.

[0157] Test case

[0158] (1) Photovoltaic conversion performance test: The perovskite solar cells prepared in the above examples and comparative examples were placed in a solar simulator (manufacturer: Wavelabs). Under the illumination of a certain solar intensity, a bias voltage (Vp, bias voltage range of -0.1V~2.1V) was applied to the device using a test source meter and the output current of the device was tested to obtain the bias voltage-current density curve.

[0159] Open-circuit voltage (Voc): The terminal voltage of the solar cell when no load is connected, i.e., when the current density in the bias-current density curve is 0 mA·cm. -2 The bias voltage value at that time.

[0160] Short-circuit current density (Jsc): The output current per unit area of ​​the solar cell when it is short-circuited, i.e., the current density when the bias voltage is 0V in the bias voltage-current density curve.

[0161] Fill factor (FF): FF = max(Vp × Jsc), where Vp is the bias voltage and Jsc is the short-circuit current density.

[0162] Photovoltaic cell efficiency (PCE): PCE = Voc × Jsc × FF. The test results are shown in Table 2.

[0163] (2) Delamination rate test: The adhesion (bonding strength) was tested using the "100-grid method". The test structures were perovskite layer / modified fullerene layer / SnO2 and perovskite layer / C60 / SnO2. To prepare this structure, the effective area was divided into 100 grids using a laser. After being adhered with adhesive tape, the grids were peeled off, and the film delamination was observed. If 10 grids were delamination, the delamination rate was 10%.

[0164] Table 2

[0165]

[0166] As shown in Table 2, by comparing Example 1 and Comparative Example 1, Example 7 and Comparative Example 2, and Example 8 and Comparative Example 3, it can be seen that the electron transport layer provided in this application has excellent electron transport capability and interfacial bonding force by connecting sulfur atoms on the surface of the fullerene material, and the perovskite solar cell has excellent photoelectric conversion efficiency.

[0167] Comparing Example 1 and Comparative Example 4, it can be seen that, compared with Comparative Example 4 which uses a co-evaporation process to form non-CS covalent sulfur doping on the fuller layer, the sulfur doping in the form of CS covalent bonds formed on the fuller layer using an atomic layer deposition process provided in this application has better electron transport capability and interfacial bonding, resulting in better photoelectric conversion efficiency of the perovskite solar cell.

[0168] Comparing Examples 1 and 9, it is evident that in Example 1, introducing ozone during the atomic layer deposition process facilitates the attack on the carbon-carbon double bond (C=C) cages on the surface of the fullerene material molecules, forming epoxy groups (COC). The active sites provided by COC more readily react with subsequently introduced hydrogen sulfide, promoting the breaking of SH bonds in the hydrogen sulfide and the formation of CS covalent bonds with carbon sites. This further enhances the electron transport capability and interfacial bonding of the electron transport layer, thereby improving the photoelectric conversion efficiency of the perovskite solar cell. Comparing Examples 1-3 and Example 6, it is evident that controlling the number of cycles and the amount and duration of ozone introduction in each cycle, thus controlling the total amount of ozone participating in the reaction, is beneficial for improving the electron transport capability and interfacial bonding of the electron transport layer, and enhancing the photoelectric conversion efficiency of the perovskite solar cell.

[0169] Comparing Examples 1 and 4-5, it can be seen that by controlling the time of sulfur source introduction in each cycle and controlling the total amount of sulfur source participating in the reaction, it is beneficial to improve the electron transport capability and interfacial bonding force of the electron transport layer, thereby enhancing the photoelectric conversion efficiency of perovskite solar cells.

[0170] Comparing Examples 1 and 7-8, it can be seen that an excessively thin fullerene material layer has limited ability to resist ozone attack, which will lead to a decrease in photoelectric conversion efficiency; an excessively thick fullerene material layer will cause it to break in the middle, resulting in a decrease in interfacial bonding. This application further improves the electron transport capability and interfacial bonding of the electron transport layer by depositing a fullerene material layer of appropriate thickness on the surface of the perovskite layer, thereby enhancing the photoelectric conversion efficiency of the perovskite solar cell.

[0171] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0172] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A perovskite solar cell, characterized in that, include: A first electrode, a perovskite layer, an electron transport layer, and a second electrode, wherein the perovskite layer is located between the first electrode and the second electrode, and the electron transport layer is located between the perovskite layer and the second electrode, and the electron transport layer comprises: A modified fullerene layer, the modified fullerene layer comprising a fullerene material and sulfur atoms located on the surface of the fullerene material, the fullerene material and the sulfur atoms being connected by CS covalent bonds; as well as A tin oxide layer is located above the modified fullerene layer and is in contact with the sulfur atoms.

2. The perovskite solar cell according to claim 1, characterized in that, The thickness of the modified fullerene layer is 5nm-30nm.

3. The perovskite solar cell according to claim 1, characterized in that, The fullerene material includes at least one of C60, C70, methyl [6,6]-phenyl-C61-butyrate, methyl [6,6]-phenyl-C71-butyrate, and indene-C60 diadduct.

4. The perovskite solar cell according to any one of claims 1-3, characterized in that, The thickness of the tin oxide layer is 5nm-30nm.

5. A method for preparing a perovskite solar cell, characterized in that, Includes the following steps: Perovskite layers were sequentially prepared on the first electrode; Fullerene material is deposited on the perovskite layer; A modified fullerene layer was prepared by atomic layer deposition by linking sulfur atoms to the fullerene material via CS covalent bonds. A tin oxide layer is prepared on the side of the modified fullerene layer where the sulfur atoms are opposite to the fullerene material; as well as A second electrode is fabricated on the tin oxide layer.

6. The method for preparing a perovskite solar cell according to claim 5, characterized in that, The method of connecting sulfur atoms to the fullerene material via CS covalent bonds by atomic layer deposition includes the following steps: performing at least one deposition cycle in an atomic layer deposition chamber, each deposition cycle including the following steps: alternately introducing ozone and sulfur sources.

7. The method for preparing a perovskite solar cell according to claim 6, characterized in that, Each deposition cycle includes the following steps: introducing ozone; introducing a first purge gas; introducing the sulfur source; introducing a second purge gas; the deposition cycle is repeated 1 to 10 times.

8. The method for preparing a perovskite solar cell according to claim 7, characterized in that, At least one of the following conditions must be met: (1) The flow rate of ozone introduced each time is 100 sccm-1000 sccm; (2) The time for each ozone introduction is 50ms-500ms; (3) The flow rate of the sulfur source introduced each time is 100 sccm-1000 sccm; (4) The time for each introduction of the sulfur source is 50ms-500ms.

9. A stacked battery, comprising a top battery and a bottom battery, characterized in that, The top cell includes a perovskite solar cell according to any one of claims 1-4 or a perovskite solar cell prepared by the method according to any one of claims 5-8.

10. A photovoltaic module, characterized in that, This includes the perovskite solar cell according to any one of claims 1-4, the perovskite solar cell prepared by the method according to any one of claims 5-8, or the tandem cell according to claim 9.

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