Perovskite solar cell and preparation method thereof

Abstract

The invention relates to a perovskite solar cell and a preparation method thereof, the perovskite solar cell comprises a first electrode layer, a hole transport layer, a perovskite layer, an electron transport layer and a second electrode layer which are stacked in sequence, and the hole transport layer and / or the electron transport layer contains a cyanophenyl compound. According to the perovskite solar cell, the cyanophenyl compound is adopted as a passivation material, the defects of the electron transport layer and the hole transport layer are passivated at the same time, non-radiative recombination at an interface is reduced, and finally the device performance of the perovskite solar cell is improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a perovskite solar cell and its fabrication method. Background Technology

[0002] Perovskite solar cells, which use metal halide perovskites as photoelectric converters, have seen rapid development in the past decade. Among them, inverted perovskite solar cells (pin-type) have attracted widespread attention and research from the academic community due to their low hysteresis effect and their extensive application in CIGS and tandem cells. However, defects such as planar or bulk defects in the transport layer of inverted perovskite solar cells, as well as energy level defects between the perovskite layer and the transport layer, limit further improvements in cell performance. Summary of the Invention

[0003] The purpose of this invention is to provide a perovskite solar cell and its fabrication method, thereby solving the problems of transport layer defects and energy level defects between the perovskite layer and the transport layer in perovskite solar cells.

[0004] To achieve the objectives of this invention, the following technical solution is provided: In a first aspect, the present invention provides a perovskite solar cell comprising a first electrode layer, a hole transport layer, a perovskite layer, an electron transport layer and a second electrode layer stacked sequentially, wherein the hole transport layer and / or the electron transport layer comprises a benzonitrile compound.

[0005] In one embodiment, the benzonitrile compound includes one or more of benzonitrile, 4-(hydroxymethyl)benzonitrile, 4-(bromomethyl)benzonitrile, isophthalonitrile, terephthalonitrile, p-aminobenzonitrile, and 4-chloromethylbenzonitrile.

[0006] In one embodiment, the hole transport layer comprises a benzonitrile compound, and the hole transport layer further comprises a hole transport material, wherein the mass ratio of the benzonitrile compound to the hole transport material in the hole transport layer is 1%-15%.

[0007] In one embodiment, the thickness of the hole transport layer is d1, which satisfies: 5nm≤d1≤20nm.

[0008] In one embodiment, the hole transport material is one or more of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine, polymethylphenylsilane, polyvinylcarbazole, and poly(p-phenylenevinyl)ethylene].

[0009] In one embodiment, the electron transport layer comprises a benzonitrile compound, and the electron transport layer further comprises an electron transport material, wherein the mass ratio of the benzonitrile compound to the electron transport material in the electron transport layer is 1%-15%.

[0010] In one embodiment, the thickness of the electron transport layer is d2, which satisfies: 10nm≤d2≤60nm.

[0011] In one embodiment, the electron transport material is fullerene, [6,6]-phenyl-C 61 One or more of the following: methyl butyrate, perfluorinated oligomeric polystyrene, cyano-containing polyphenylene oxide, titanium dioxide, and tin oxide.

[0012] In a second aspect, the present invention provides a method for preparing a perovskite solar cell, used to prepare a perovskite solar cell as described in any of the various embodiments of the first aspect, comprising: The first mixture is dissolved in the first solvent to obtain the first precursor solution; The first precursor solution is disposed on the first electrode layer, and the first solvent is removed to obtain a hole transport layer. A perovskite layer is prepared on the hole transport layer; The second mixture is dissolved in a second solvent to obtain a second precursor solution; The second precursor solution is deposited on the perovskite layer, and the second solvent is removed to obtain an electron transport layer; A second electrode layer is fabricated on the electron transport layer to obtain a perovskite solar cell. The first mixture and / or the second mixture contain benzonitrile compounds.

[0013] In one embodiment, the first solvent and the second solvent include one or more of chlorobenzene, toluene, o-dichlorobenzene, chloroform, propionic acid, and ethanol.

[0014] This invention employs benzonitrile compounds to optimize the electron transport layer and hole transport layer of perovskite solar cells. The cyano groups in benzonitrile compounds, due to their high electronegativity and strong interactions with atoms and iodine vacancies in the perovskite layer, can enhance the connection between the perovskite layer and the hole transport layer. Furthermore, the carbon-nitrogen triple bonds provided by benzonitrile compounds can form hydrogen bonds with some of the highly electronegative carboxyl groups in the electron transport layer, enabling the molecules in the electron transport layer to arrange themselves in an orderly manner. Therefore, benzonitrile compounds, as passivation materials, can simultaneously passivate defects in both the electron transport layer and the hole transport layer, reduce non-radiative recombination at the interface, and ultimately improve the device performance of perovskite solar cells. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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 from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a perovskite solar cell according to one embodiment; Figure 2 A scanning electron microscope image of a perovskite solar cell according to one embodiment; Figure 3 This is a flowchart illustrating a method for fabricating a perovskite solar cell according to one embodiment; Figure 4 This is a comparison graph of the current density-voltage curves of the perovskite solar cells of Example 1 and Comparative Example 1.

[0017] Explanation of reference numerals in the attached figures: 100 - Perovskite solar cell, 10 - First electrode layer, 20 - Hole transport layer, 30 - Perovskite layer, 40 - Electron transport layer, 50 - Second electrode layer. Detailed Implementation

[0018] 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 a part of the embodiments of the present invention, and not all of them. 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.

[0019] It should be noted that when a component is said to be "fixed" to another component, it can be directly on the other component or it can be in a middle component. When a component is said to be "connected" to another component, it can be directly connected to the other component or it may be in a middle component.

[0020] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0022] Please refer to Figure 1 and Figure 2 ,in, Figure 2 This is a scanning electron microscope image of a perovskite solar cell 100 according to an embodiment. The present invention provides a perovskite solar cell 100, comprising a first electrode layer 10, a hole transport layer 20, a perovskite layer 30, an electron transport layer 40, and a second electrode layer 50 stacked sequentially, wherein the hole transport layer 20 and / or the electron transport layer 40 contain benzonitrile compounds.

[0023] Optionally, the first electrode layer 10 is a transparent conductive electrode, specifically formed from transparent conductive materials such as indium tin oxide (ITO) or fluorine-doped tin oxide (FTO). The first electrode layer 10 allows sunlight to pass through and be transmitted into the battery, ensuring efficient light utilization. Simultaneously, it collects electrons generated by the perovskite layer 30 and transmits them to the external circuit to form a current. The first electrode layer 10 also protects the perovskite layer 30 from damage by the external environment, such as moisture and oxygen. It collects electrons generated by the perovskite layer 30 and transmits them to the external circuit to form a current.

[0024] Optionally, the second electrode layer 50 is a back electrode. The second electrode layer 50 can be a metal electrode, a carbon-based electrode, or a composite electrode, specifically gold, silver, carbon, NiO / Ag / NiO composite structures, etc., without limitation. The second electrode layer 50 is used to form good contact with the perovskite layer 30 and the charge transport layer, reduce recombination losses, and improve the lifetime of the perovskite solar cell 100.

[0025] Optionally, the perovskite layer 30 has the chemical formula ABX3, where A is an organic or inorganic cation, B is a divalent metal ion, and X is a monovalent halide ion. Specifically, A = CH3NH3, NH2CHNH2, Cs, or a mixture thereof; B = Pb or a mixture thereof; and X = I, Br, or a mixture thereof. Upon absorbing sunlight, electrons in the perovskite layer 30 transition from the valence band to the conduction band, forming electron-hole pairs (excitons). The dissociated electrons are transported through the conduction band of the perovskite layer 30 to the electron transport layer 40, while holes are transported through the valence band to the hole transport layer 20, forming a closed loop. The benzene ring and cyano group in the benzonitrile compound passivate the surface defects of the perovskite layer 30, improving the carrier transport efficiency in the perovskite solar cell 100 device.

[0026] Optionally, the thickness of the perovskite layer 30 is 200nm-500nm. Specifically, the thickness of the perovskite layer 30 can be 200nm, 240nm, 260nm, 280nm, 300nm, 340nm, 360nm, 380nm, 400nm, 440nm, 460nm, 480nm, 500nm, etc., without limitation.

[0027] This invention employs benzonitrile compounds to optimize the electron transport layer 40 and hole transport layer 20 of a perovskite solar cell 100. The cyano groups of the benzonitrile compounds, due to their high electronegativity and strong interactions with atoms and iodine vacancies in the perovskite layer 30, can enhance the connection between the perovskite layer 30 and the hole transport layer 20. Furthermore, the carbon-nitrogen triple bonds provided by the benzonitrile compounds can form hydrogen bonds with some of the highly electronegative carboxyl groups in the electron transport layer 40, enabling the molecules of the electron transport layer 40 to arrange themselves in an orderly manner. Therefore, benzonitrile compounds, as passivation materials, can simultaneously passivate defects in both the electron transport layer 40 and the hole transport layer 20, reduce non-radiative recombination at the interface, and ultimately improve the device performance of the perovskite solar cell 100.

[0028] In one embodiment, the benzonitrile compound includes one or more of benzonitrile, 4-(hydroxymethyl)benzonitrile, 4-(bromomethyl)benzonitrile, isophthalonitrile, terephthalonitrile, p-aminobenzonitrile, and 4-chloromethylbenzonitrile.

[0029] In benzonitrile compounds, the carbon and nitrogen atoms in the cyano group are connected by a triple bond, forming a highly polarized covalent bond. The electron cloud is strongly biased towards the nitrogen atom, making the carbon atom electron-deficient and the cyano group a strong electron-withdrawing group. This allows it to attract surrounding electrons through electrostatic interactions, thereby modulating the charge distribution on the material surface. Uncoordinated metal ions or halogen vacancies often exist on the surfaces of the hole transport layer 20 and electron transport layer 40. These defects can become carrier recombination centers, reducing device efficiency. Therefore, benzonitrile compounds with cyano groups can fill defect sites by forming coordinate bonds between the electron-deficient carbon atom of the cyano group and uncoordinated metal ions, reducing non-radiative recombination. Furthermore, the polarity of the cyano group can neutralize the local charge around the defects, reducing the defects' ability to trap carriers.

[0030] In addition, the benzene ring in benzonitrile compounds, through steric hindrance, electron cloud regulation and synergistic passivation effects, together with the cyano group, optimizes the surface state of the electron transport layer 40, thereby reducing the impact of defects on device performance.

[0031] In one embodiment, the hole transport layer 20 comprises a benzonitrile compound and a hole transport material, wherein the mass ratio of the benzonitrile compound to the hole transport material in the hole transport layer 20 is 1%-15%.

[0032] Optionally, the mass ratio of benzonitrile compounds to hole transport materials can be 1%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, etc., without limitation.

[0033] When the mass ratio of benzonitrile compound to hole transport material is too high, the mass of hole transport material is too low, and holes cannot be effectively extracted and transported, leading to the accumulation of photogenerated carriers at the interface between perovskite layer 30 and hole transport material, resulting in severe recombination loss. When the mass ratio of benzonitrile compound to hole transport material is too low, the mass of benzonitrile compound is too low, and it cannot significantly improve the connection between perovskite layer 30 and hole transport layer 20. When the mass ratio of benzonitrile compound to hole transport material is moderate, the hole transport material can provide enough holes to ensure hole mobility, and at the same time, the benzonitrile compound can significantly improve the connection between perovskite layer 30 and hole transport layer 20.

[0034] Please refer to Figure 1 and Figure 2 In one embodiment, the thickness of the hole transport layer 20 is d1, which satisfies: 5nm≤d1≤20nm.

[0035] Optionally, the thickness d1 of the hole transport layer 20 can be 5nm, 8nm, 10nm, 12nm, 15nm, 16nm, 18nm, 20nm, etc., without limitation.

[0036] If the hole transport layer 20 is too thick, it will prolong the transport path of holes from the perovskite layer 30 to the first electrode layer 10, increasing the resistance to carrier migration, leading to a decrease in hole mobility, and increasing the probability of carrier recombination during transport. This reduces the short-circuit current density (Jsc) and fill factor (FF) of the perovskite solar cell 100, ultimately affecting the photoelectric conversion efficiency (PCE). If the hole transport layer 20 is too thin, it may lead to uneven coverage, forming pinholes or defects. In the perovskite solar cell 100, pinhole defects can become carrier recombination centers, reducing Jsc and FF. If the hole transport layer 20 is too thin, it may not be able to effectively block electrons from being injected back into the perovskite layer 30 from the first electrode layer 10, resulting in a decrease in open-circuit voltage. Furthermore, if the hole transport layer 20 is too thin, it may result in poor interfacial bonding with adjacent layers (such as the perovskite layer 30 and the first electrode layer 10). When the hole transport layer 20 has a moderate thickness, it can ensure both the bonding strength with the adjacent interface and that the hole transport path does not affect the transport efficiency of the charge carriers.

[0037] In one embodiment, the hole transport material is one or more of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine, polymethylphenylsilane, polyvinylcarbazole, and poly(p-phenylenevinyl)ethylene].

[0038] After absorbing photons, the perovskite layer 30 generates electron-hole pairs (excitons). The hole transport layer 20, through its high-mobility material, selectively extracts and transports holes to the first electrode layer 10. The cyano group of the benzonitrile compound, as a strong electron-withdrawing group, can lower the highest occupied molecular orbital (HOMO level) of the hole transport material, making it more compatible with the valence band level of the perovskite layer 30. This reduces the hole extraction barrier and promotes the efficient transfer of holes from the perovskite layer 30 to the hole transport layer 20.

[0039] In one embodiment, the electron transport layer 40 comprises a benzonitrile compound and an electron transport material, wherein the mass ratio of the benzonitrile compound to the electron transport material in the electron transport layer 40 is 1%-15%.

[0040] Optionally, the mass ratio of benzonitrile compounds to electron transport materials can be 1%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, etc., without limitation.

[0041] When the mass ratio of benzonitrile compound to electron transport material is too small, the excessive mass of electron transport material may lead to excessively thick films or increased surface roughness. An excessively high mass ratio may also cause the conduction band position of electron transport layer 40 to deviate from the ideal value, resulting in energy level mismatch with perovskite layer 30, increasing carrier recombination at the interface, reducing open-circuit voltage (Voc), and thus affecting battery efficiency. Furthermore, benzonitrile compound cannot adequately passivate defects within electron transport layer 40. Conversely, when the mass ratio of benzonitrile compound to electron transport material is too large, the proportion of electron transport material is small, which may prevent electron transport layer 40 from effectively collecting and transporting electrons, increasing series resistance within the battery, reducing short-circuit current (Jsc) and fill factor (FF), thus affecting battery performance. Increased interface defects and an excessively thin or incompletely covered electron transport layer 40 may increase the defect state density at the interface, reducing open-circuit voltage and battery efficiency. When the mass ratio of benzonitrile compound to electron transport material is moderate, the electron transport material can effectively collect and transport electrons. Simultaneously, benzonitrile compound can significantly improve the connection between perovskite layer 30 and hole transport layer 20.

[0042] Please refer to Figure 1 and Figure 2 In one embodiment, the thickness of the electron transport layer 40 is d2, which satisfies: 20nm≤d2≤60nm.

[0043] Optionally, the thickness d2 of the electron transport layer 40 can be 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, etc., without limitation.

[0044] When the electron transport layer 40 is too thick, it prolongs the electron transport path from the perovskite layer 30 to the second electrode layer 50, increasing the resistance to electron migration, leading to a decrease in electron mobility and an increased probability of electron recombination with holes during transport. Furthermore, an excessively thick electron transport layer 40 may increase light absorption, reducing the number of photons reaching the perovskite layer 30 and thus lowering the short-circuit current density. If the electron transport layer 40 is too thin, it may not effectively block the migration of iodine ions and may also cause uneven coverage, forming pinholes or defects. When the electron transport layer 40 has a moderate thickness, the electron transport path from the perovskite layer 30 to the second electrode layer 50 is moderate, the electron mobility is high, and the moderately thick electron transport layer 40 can also ensure the interfacial bonding strength with the adjacent perovskite layer 30 and second electrode layer 50.

[0045] In one embodiment, the electron transport material is fullerene, [6,6]-phenyl-C 61 One or more of the following: methyl butyrate, perfluorinated oligomeric polystyrene, cyano-containing polyphenylene oxide, titanium dioxide, and tin oxide.

[0046] Specifically, the electron transport material is [6,6]-phenyl-C 61 When methyl butyrate (PCBM) is used, the carbon-nitrogen triple bond provided by benzonitrile compounds can form hydrogen bonds with the highly electronegative carboxyl groups in PCBM, enabling the molecules of electron transport layer 40 to be arranged in an orderly manner, forming a regular crystal structure or a highly oriented molecular layer, reducing the scattering and trapping of charge carriers (electrons) during transport.

[0047] Electron transport layer 40, through its high electron mobility material, selectively extracts electrons from perovskite layer 30 and transports them to the subsequent second electrode layer 50. The strong electron-withdrawing properties of the cyano group in the benzonitrile compound lower the lowest unoccupied molecular orbital (LUMO) energy level of the electron transport material, making it more compatible with the energy level of perovskite layer 30, thereby reducing the electron injection barrier and improving electron extraction efficiency. The introduction of the cyano group also enhances intermolecular π-π interactions or hydrogen bonding, forming a more compact packing structure and reducing scattering and trapping during carrier transport.

[0048] Please refer to Figure 3 This invention provides a method for preparing a perovskite solar cell, used to prepare the perovskite solar cell described in any of the foregoing embodiments, comprising: Step S10: Dissolve the first mixture in the first solvent to obtain the first precursor solution; Step S20: The first precursor liquid is placed on the first electrode layer and the first solvent is removed to obtain the hole transport layer. Step S30: Prepare a perovskite layer on the hole transport layer; Step S40: Dissolve the second mixture in a second solvent to obtain a second precursor solution; Step S50: The second precursor solution is placed on the perovskite layer, and the second solvent is removed to obtain the electron transport layer. Step S60: A second electrode layer is prepared on the electron transport layer to obtain a perovskite solar cell.

[0049] The first mixture and / or the second mixture contain benzonitrile compounds.

[0050] Optionally, in step S20, the preparation of the first electrode layer includes: cleaning a transparent conductive glass substrate; and subjecting the conductive glass substrate to ultraviolet (UV) treatment. Specifically, the UV treatment can involve irradiating the substrate with an ultraviolet ozone cleaner for 15 minutes.

[0051] Optionally, in steps S20, S30, and S50, the hole transport layer, perovskite layer, and electron transport layer can be prepared using solution methods, vapor deposition, etc. Solution methods can specifically include wet processes such as spin coating and slot coating, while vapor deposition can specifically include dry processes such as vacuum evaporation and sputtering. Specifically, spin coating involves rotating the substrate at high speed, using centrifugal force to evenly spread the solution and remove excess solvent, ultimately forming a thin film. As the rotation speed increases, the centrifugal force significantly increases, causing more solution to be ejected from the substrate edge, reducing the amount of residual solution and resulting in a thinner film. Conversely, at lower speeds, the centrifugal force is smaller, resulting in more residual solution and a thicker film. Therefore, when using spin coating to prepare the hole transport layer, the rotation speed can be 3000 rpm-5000 rpm, and the spin coating time can be 20 s-60 s, etc., without limitation. When preparing an electron transport layer using spin coating, the rotation speed can be 1000rpm-3000rpm, and the spin coating time can be 20s-60s, etc., without any restrictions.

[0052] Optionally, in step S20, the method for removing the first solvent can be natural evaporation, annealing, heating, etc., without limitation.

[0053] Optionally, the preparation process of the perovskite layer in step S30 can be as follows: The perovskite layer uses a material with the chemical formula ABX3. The required amount of material with corresponding elements is weighed out in a molar ratio and dissolved in a mixed solvent. Additives are added to increase the crystallinity of the perovskite. The mixture is stirred and filtered to obtain a perovskite solution. Specifically, 781.2 mg PbI2, 13 mg PbBr2, 3.68 mg MABr, 276.87 mg FAI, and 22.5 mg CsI are weighed and added to a mixed solution of 0.833 mL N,N-dimethylformamide (DMF) and 0.167 mL dimethyl sulfoxide (DMSO). Then, 17.82 mg methyl ammonium chloride (MACl) is added to increase the crystallinity of the perovskite. The mixture is stirred for 2 hours. After the solution is completely dissolved, it is filtered using a 22 μm filter.

[0054] Optionally, in step S60, the second electrode layer is a metal electrode layer, specifically prepared by evaporation deposition. The product obtained in step S50 is placed into the mask of the evaporation deposition equipment, and the metal second electrode layer is obtained by evaporation deposition under a vacuum of 10⁻⁵.

[0055] Optionally, when the hole transport layer and / or electron transport layer contains benzonitrile compounds, benzonitrile compounds are added to the first mixture in step S10 and the second mixture in step S50 in a mass ratio. In step S10, the benzonitrile compound and the hole transport material are dissolved in a first solvent in a mass ratio, and in step S50, the benzonitrile compound and the electron transport material are dissolved in a second solvent in a mass ratio.

[0056] In one embodiment, the first solvent and the second solvent include one or more of chlorobenzene, toluene, o-dichlorobenzene, chloroform, propionic acid, and ethanol.

[0057] The first solvent and the second solvent can be the same or different, without restriction.

[0058] The use of a first solvent and a second solvent allows for thorough and uniform mixing of benzonitrile compounds and hole transport materials, as well as benzonitrile compounds and electron transport materials, facilitating the subsequent formation of thin-layer structures.

[0059] The technical solution of the present invention will be described in detail below through specific embodiments.

[0060] Example 1 In this embodiment, the benzonitrile compound is 4-chloromethylbenzonitrile (CBN), the hole transport material is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA), and the electron transport material is [6,6]-phenyl-C 61 - Methyl butyrate, the first electrode layer is ITO conductive glass, the second electrode layer is a silver electrode, and the thickness of the perovskite layer is 460nm.

[0061] The hole transport layer has a thickness d1 of 15 nm and the electron transport layer has a thickness d2 of 50 nm.

[0062] The specific preparation process of Example 1 is as follows: CBN and PTAA are dissolved in chlorobenzene at a mass ratio of 1:10 and stirred thoroughly to obtain the first precursor solution; the cleaned ITO conductive glass is irradiated with an ultraviolet ozone cleaner for 15 min before coating; 45 μL of the first precursor solution is dropped onto the ultraviolet ozone-treated ITO substrate, spin-coated at 4000 rpm for 30 s, and then annealed on a heating stage at 100℃ for 10 min to obtain the hole transport layer; a perovskite layer is prepared by spin-coating on the hole transport layer (the preparation of the perovskite layer solution corresponding to the perovskite layer is described above); CBN and PCBM are dissolved in chlorobenzene at a mass ratio of 1:20 and stirred thoroughly to obtain the second precursor solution; 35 μL of the second precursor solution is dropped onto the perovskite layer that has been cooled to room temperature, spin-coated at 1600 rpm for 30 s to obtain the electron transport layer; a 100 nm silver electrode is vacuum thermally deposited on the electron transport layer as the second electrode layer to obtain the perovskite solar cell.

[0063] Example 2 The benzonitrile compound in this embodiment is 4-(hydroxymethyl)benzonitrile (HBN), and the other parameters are the same as in Example 1.

[0064] The difference between the preparation process in this embodiment and that in Example 1 is as follows: HBN and PTAA are dissolved in chlorobenzene at a mass ratio of 1:10 and stirred thoroughly to obtain the first precursor solution; HBN and PCBM are dissolved in chlorobenzene at a mass ratio of 1:20 and stirred thoroughly to obtain the second precursor solution.

[0065] Example 3 The benzonitrile compound in this embodiment is p-aminobenzonitrile (ABN), and the other parameters are the same as in Example 1.

[0066] The difference between the preparation process in this embodiment and that in Example 1 is as follows: ABN and PTAA are dissolved in chlorobenzene at a mass ratio of 1:10 and stirred thoroughly to obtain the first precursor solution; ABN and PCBM are dissolved in chlorobenzene at a mass ratio of 1:20 and stirred thoroughly to obtain the second precursor solution.

[0067] Example 4 The benzonitrile compound in this embodiment is 4-(bromomethyl)benzonitrile (BBN), and the other parameters are the same as in Example 1.

[0068] The difference between the preparation process in this embodiment and that in Example 1 is as follows: BBN and PTAA are dissolved in chlorobenzene at a mass ratio of 1:10 and stirred thoroughly to obtain the first precursor solution; BBN and PCBM are dissolved in chlorobenzene at a mass ratio of 1:20 and stirred thoroughly to obtain the second precursor solution.

[0069] Example 5 In this embodiment, only CBN is added to the hole transport layer, while there is no CBN in the electron transport layer. The other parameters are the same as in Embodiment 1.

[0070] The difference between the preparation process in this embodiment and that in Example 1 is that 20 mg of PCBM is dissolved in 1 mL of chlorobenzene and stirred thoroughly to obtain the second precursor solution.

[0071] Example 6 In this embodiment, only CBN is added to the electron transport layer, while there is no CBN in the hole transport layer. The other parameters are the same as in Embodiment 1.

[0072] The difference between the preparation process in this embodiment and that in Example 1 is that 2 mg of PTAA is dissolved in 1 mL of chlorobenzene and stirred thoroughly to obtain the first precursor solution.

[0073] Example 7 In this embodiment, the mass ratio of CBN to PTAA is 5%, and the remaining parameters are the same as in Example 1.

[0074] The difference between the preparation process in this embodiment and that in Example 1 is that CBN and PTAA are dissolved in chlorobenzene at a mass ratio of 5%, and stirred thoroughly to obtain the first precursor solution.

[0075] Example 8 In this embodiment, the mass ratio of CBN to PTAA is 15%, and the other parameters are the same as in Example 1.

[0076] The difference between the preparation process in this embodiment and that in Example 1 is that CBN and PTAA are dissolved in chlorobenzene at a mass ratio of 15%, and stirred thoroughly to obtain the first precursor solution.

[0077] Example 9 In this embodiment, the mass ratio of CBN to PTAA is 20%, and the other parameters are the same as in Example 1.

[0078] The difference between the preparation process in this embodiment and that in Example 1 is that CBN and PTAA are dissolved in chlorobenzene at a mass ratio of 20%, and stirred thoroughly to obtain the first precursor solution.

[0079] Example 10 In this embodiment, the mass ratio of CBN to PCBM is 2.5%, and the other parameters are the same as in Embodiment 1.

[0080] The difference between the preparation process in this embodiment and that in Example 1 is that CBN and PCBM are dissolved in chlorobenzene at a mass ratio of 2.5%, and stirred thoroughly to obtain the second precursor solution.

[0081] Example 11 In this embodiment, the mass ratio of CBN to PCBM is 7.5%, and the remaining parameters are the same as in Embodiment 1.

[0082] The difference between the preparation process in this embodiment and that in Example 1 is that CBN and PCBM are dissolved in chlorobenzene at a mass ratio of 7.5%, and stirred thoroughly to obtain the second precursor solution.

[0083] Example 12 In this embodiment, the mass ratio of CBN to PCBM is 10%, and the other parameters are the same as in Embodiment 1.

[0084] The difference between the preparation process in this embodiment and that in Example 1 is that CBN and PCBM are dissolved in chlorobenzene at a mass ratio of 10%, and stirred thoroughly to obtain the second precursor solution.

[0085] Comparative Example 1 In this comparative example, no benzonitrile compounds were found in either the electron transport layer or the hole transport layer.

[0086] The perovskite solar cells prepared in Examples 1-12 and Comparative Example 1 were characterized for photoelectric conversion efficiency. The main characterization parameters were short-circuit current density (J), open-circuit voltage (V), fill factor (FF), and photoelectric conversion efficiency (PCE). The testing principle is as follows: Here, short-circuit current density refers to the current density passing through the device under illumination without external bias voltage, i.e., when the device is in a short-circuit state. Open-circuit voltage refers to the voltage across the battery terminals when the current through the battery is zero under illumination. Fill factor is the ratio of the maximum output power per unit area of ​​the battery to the product of the open-circuit voltage and the short-circuit current density; its formula is:

[0087] Photoelectric conversion efficiency (PCE) refers to the maximum output power P per unit area of ​​a device. max With incident light irradiance P in The ratio, its formula is:

[0088] The prepared perovskite solar cells were characterized as described above under the following test conditions: AM1.5G simulated sunlight, i.e., solar radiation spectrum passing through 1.5 atmospheres and taking into account atmospheric scattering, with a corresponding irradiance of 1000 mW·cm⁻¹. -2 The scanning voltage range is -0.1V to 1.3V.

[0089] The test results are shown in the table below.

[0090]

[0091] From Table 1 and Figure 4 It can be seen that the parameters of the perovskite solar cell optimized by CBN are comprehensively improved. Among them, Figure 4 In the figure, a1 represents the JV curve of the perovskite solar cell in Example 1. Figure 4 In the figure, a2 is the JV curve of the perovskite solar cell in Comparative Example 1, which is derived from... Figure 4 It can be seen that, under the same voltage, the current density of the perovskite solar cell in Example 1 is always greater than that of the perovskite solar cell in Comparative Example 1, and the maximum photoelectric conversion efficiency (PCE) of Comparative Example 1 is 16.49%, while the maximum PCE of Example 1 is increased to 20.1%. This shows that the parameters of the perovskite solar cell optimized with CBN are comprehensively improved.

[0092] The test results from Comparative Examples 1-4 and Comparative Example 1 show that different types of benzonitrile compounds can improve perovskite solar cells. The photoelectric conversion efficiency of perovskite solar cells with added benzonitrile compounds is superior to that without added benzonitrile compounds. Benzonitrile compounds can improve the short-circuit current density and fill factor of perovskite solar cells, thereby improving their photoelectric conversion efficiency.

[0093] As shown in Comparative Examples 1, 5, and 6, and Comparative Example 1, the photoelectric conversion efficiency of perovskite solar cells with benzonitrile compounds added only to the electron transport layer or hole transport layer is higher than that of perovskite solar cells without benzonitrile compounds, but lower than that of perovskite solar cells with benzonitrile compounds optimized in both transport layers. The short-circuit current density and fill factor of perovskite solar cells with only one optimized transport layer are lower than those of perovskite solar cells with optimized transport layers, resulting in a lower photoelectric conversion efficiency for the corresponding perovskite solar cells.

[0094] As shown in Comparative Examples 1 and 7-9, with other parameters remaining constant, the open-circuit voltage, short-circuit current density, and fill factor of the perovskite solar cell all show a trend of first increasing and then decreasing with the increase of the mass ratio of benzonitrile compound to hole transport material. Correspondingly, the photoelectric conversion efficiency of the perovskite solar cell also first increases and then decreases. The ratio of the two affects the number of holes that the hole transport material can increase and the connection between the perovskite layer and the hole transport layer. Therefore, it is necessary to control the mass ratio of benzonitrile compound to hole transport material within a suitable range, avoiding both excessively high and low ratios. However, all of these results are superior to the perovskite solar cell in Comparative Example 1.

[0095] Comparative Examples 1 and 10-12 show that, with other parameters unchanged, as the mass ratio of benzonitrile compound to electron transport material increases, the open-circuit voltage, short-circuit current density, and fill factor of the perovskite solar cell all show a trend of first increasing and then decreasing. Correspondingly, the photoelectric conversion efficiency of the perovskite solar cell first increases and then decreases. The ratio affects the passivation effect of the benzonitrile compound on the electron transport layer and the number of electrons that the electron transport layer can collect and transport. Therefore, it is necessary to control the mass ratio of benzonitrile compound to electron transport material within a suitable range, avoiding both excessively high and low ratios. However, all are superior to the perovskite solar cell of Comparative Example 1.

[0096] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship of the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and other indicators are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0097] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A perovskite solar cell, characterized by, The perovskite solar cell comprises a first electrode layer, a hole transport layer, a perovskite layer, an electron transport layer and a second electrode layer which are sequentially stacked, wherein the hole transport layer and / or the electron transport layer comprises a benzonitrile compound.

2. The perovskite solar cell according to claim 1, characterized in that, The benzonitrile compound comprises one or more of benzonitrile, 4-(hydroxymethyl)benzonitrile, 4-(bromomethyl)benzonitrile, isophthalonitrile, terephthalonitrile, p-aminobenzonitrile and 4-chloromethylbenzonitrile. 3.The perovskite solar cell of claim 1, wherein, The hole transport layer comprises the benzonitrile compound and a hole transport material, and the mass ratio of the benzonitrile compound to the hole transport material in the hole transport layer is 1%-15%.

4. The perovskite solar cell according to claim 3, characterized in that, The thickness of the hole transport layer is d1, and 5nm≤d1≤20nm is satisfied.

5. The perovskite solar cell according to claim 3, characterized in that, The hole transport material is one or more of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine, polymethylphenylsilane, polyvinylcarbazole and poly-p-phenylenevinylene. 6.The perovskite solar cell of claim 1, wherein, The electron transport layer comprises the benzonitrile compound and an electron transport material, and the mass ratio of the benzonitrile compound to the electron transport material in the electron transport layer is 1%-15%.

7. The perovskite solar cell according to claim 6, characterized in that, The thickness of the electron transport layer is d2, and 10nm≤d2≤60nm is satisfied.

8. The perovskite solar cell according to claim 6, characterized in that, The electron transport material is fullerene, [6,6]-phenyl-C 61 - one or more of methyl butyrate, perfluoro-oligo-phenyls, polycyanophenylene-vinylene, titanium dioxide, tin oxide.

9. A method for producing a perovskite solar cell, for producing a perovskite solar cell according to any one of claims 1 to 8, characterized in that, The perovskite solar cell comprises: dissolving a first mixture in a first solvent to obtain a first precursor solution; arranging the first precursor solution on a first electrode layer and removing the first solvent to obtain a hole transport layer; preparing a perovskite layer on the hole transport layer; dissolving a second mixture in a second solvent to obtain a second precursor solution; arranging the second precursor solution on the perovskite layer and removing the second solvent to obtain an electron transport layer; preparing a second electrode layer on the electron transport layer to obtain the perovskite solar cell; The first mixture and / or the second mixture comprises a benzonitrile compound. 10.The method of claim 9, wherein the perovskite solar cell is prepared by the steps of: The first solvent and the second solvent comprise one or more of chlorobenzene, toluene, o-dichlorobenzene, chloroform, propionic acid and ethanol.

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