Benzimidazole modified perovskite layer and application thereof in inverse perovskite battery

Abstract

The invention belongs to the field of photoelectric materials, and relates to a benzimidazole modified perovskite layer and application thereof in an inverted perovskite battery. The perovskite layer is a film modified by introducing a benzimidazole compound containing sulfydryl and carboxyl. The benzimidazole compound containing the sulfydryl and the carboxyl is a compound which has a benzimidazole plane skeleton and simultaneously has a sulfydryl functional group (C = S) and a carboxyl functional group (-COOH); the concentration of the benzimidazole compound containing sulfydryl and carboxyl in the perovskite precursor solution is 0.05 to 0.2 mg / mL. The perovskite layer is used for improving the efficiency of the inverted perovskite cell. When the perovskite solar cell is prepared from the perovskite layer modified by the benzimidazole compound small molecules, the efficiency of the cell can be improved, and the highest efficiency breaks through 27%. The perovskite layer is especially suitable for a polycation perovskite system, the phase separation problem and defect in the crystallization process are solved, and the cell efficiency and stability are improved.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials, and particularly relates to a benzimidazole-modified perovskite layer and its application in inverted perovskite solar cells. Background Technology

[0002] Perovskite solar cells (PSCs) are based on the use of perovskite materials as the photoelectric conversion layer, theoretically achieving solar energy conversion efficiencies far exceeding those of traditional silicon-based solar cells. Their high efficiency and solution processability have made them a research hotspot, especially metal halide perovskites, which show great potential in developing cost-effective photovoltaic cells. Due to their excellent photoelectric performance, the photoelectric conversion efficiency (PCE) of perovskite solar cells (PSCs) has been continuously improving in just over a decade, and its efficiency is now comparable to that of crystalline silicon cells, which have been developed for over half a century. However, their industrialization is limited by low stability and difficulties in large-area fabrication. Inverted PSCs (i-PSCs) have attracted widespread attention from researchers due to their excellent stability and simple fabrication process. Compared to conventional forward-order structures, inverted perovskite solar cells (i-PSCs) typically exhibit better long-term stability, but their current PCE is still lower than that of conventional perovskite solar cells. This is mainly due to many defects in existing halide perovskite solar cells, such as Pb... 2+ The deep trap states caused by uncoordinated cations and I, as well as anion and lead clusters, lead to nonradiative recombination and low fill factor (FF) due to the weak antibonding between lead, ultimately affecting the efficiency of perovskite solar cells.

[0003] Furthermore, the shallow charged level defects caused by organic cation vacancies in perovskites readily induce ion migration, which not only leads to the migration of uncoordinated Pb 2+ Acting as electron traps, these additives can also decompose the perovskite layer, thereby reducing device stability. Particularly during the crystallization of multi-cation perovskites (such as FACsMA-based perovskites), component segregation and PbI2 impurity formation are prone to occur, leading to non-radiative recombination and performance degradation. Existing additive strategies mostly focus on passivating single defects, lacking overall control over the crystallization path.

[0004] Chinese patent document CN118555883A discloses a molecularly modified perovskite solar cell and its preparation method, including the steps of preparing a molecular additive solution and preparing a molecularly modified perovskite solar cell. This prior art also provides a cell obtained by the aforementioned preparation method. This prior art utilizes stilbene-benzimidazole salt molecules to modify perovskite crystals. It employs a method of first spin-coating a perovskite precursor solution to form a perovskite layer, then spin-coating a molecular additive onto its surface, and finally performing in-situ crosslinking through ultraviolet irradiation to form a specific polymer molecular crosslinking network, thereby improving the charge transport and exchange efficiency at the interface of the perovskite light-absorbing layer. However, this prior art uses stilbene-benzimidazole salt, whose functional groups are vinyl and benzimidazole salt groups. Its function is to form a polymer network through ultraviolet irradiation crosslinking, optimizing charge transport. Its mechanism of action is that the stilbene-benzimidazole salt forms a network through photocrosslinking, focusing on optimizing interfacial charge transport. However, the functional groups do not contain thiol or carboxyl groups, and therefore cannot form strong coordination bonds with the perovskite phase, resulting in weak crystallization control; its main focus is on interface modification. Furthermore, this existing technology relies on ultraviolet irradiation for processing, which is a relatively complex process.

[0005] Chinese patent document CN119219694A discloses a low-dimensional perovskite single crystal, a low-dimensional / three-dimensional perovskite thin film, a perovskite solar cell, and a preparation method thereof. The low-dimensional perovskite single crystal is specifically synthesized using the organic spacer molecule benzimidazole or its derivatives, thereby broadening the variety of low-dimensional perovskites. Simultaneously, the low-dimensional perovskite single crystal is applied to three-dimensional perovskite materials to modify and improve them, preparing low-dimensional / three-dimensional perovskite thin films with higher crystallinity and stronger hydrophobicity. These low-dimensional / three-dimensional perovskite thin films are then used as the light-absorbing layer of perovskite solar cells, ultimately improving the energy conversion efficiency of perovskite solar cells. However, this prior art uses benzimidazole, 6-methylbenzimidazole, or 6-trifluoromethylbenzimidazole for modification, with functional groups mainly being alkyl or haloalkyl (such as -CH3, -CF3). Their function is to form a low-dimensional perovskite structure through steric hindrance, modifying the surface of the three-dimensional perovskite. Its mechanism of action is mainly to use benzimidazole derivatives as spacer molecules to play a steric hindrance effect and improve film stability through the hydrophobicity of alkyl chains. However, it lacks multi-site coordination ability and has limited passivation of defects.

[0006] In summary, improving the photoelectric conversion efficiency of inverted perovskite solar cells through strategies such as interface manipulation, thin film optimization, and carrier transport layer design is an important research direction in this field. Researchers have tried various methods, including interface engineering, solvent engineering, and additive engineering. Among these, introducing additives into the perovskite layer is an effective method that can regulate the crystallization process of perovskite, reduce defects, improve film quality, and thus enhance the photoelectric performance of the cell. Benzimidazole compounds, as nitrogen-containing heterocyclic compounds, possess unique electronic structures and chemical properties, and have broad application prospects in the field of optoelectronic materials.

[0007] Therefore, it is necessary to develop a benzimidazole-modified perovskite layer and its application in inverted perovskite solar cells, using benzimidazole compounds to improve the efficiency of perovskite solar cells. Summary of the Invention

[0008] The purpose of this invention is to provide a benzimidazole-modified perovskite layer and its application in inverted perovskite solar cells. Using benzimidazole compounds (2M5BA) as small molecule additives to prepare the perovskite layer can improve the performance of perovskite solar cells; it is particularly suitable for multi-cation perovskite systems to solve phase separation and defect problems during crystallization, thereby improving cell efficiency and stability.

[0009] To solve the aforementioned technical problems, the present invention specifically adopts the following technical solution: A first aspect of the present invention is to provide a benzimidazole-modified perovskite layer, wherein the perovskite layer is a thin film modified with benzimidazole compounds containing thiol and carboxyl groups.

[0010] Preferably, the benzimidazole compound containing thiol and carboxyl groups is a compound having a benzimidazole planar skeleton and having a thiol functional group (C=S) and a carboxyl functional group (-COOH), and the concentration of the benzimidazole compound containing thiol and carboxyl groups in the perovskite precursor solution is 0.05-0.2 mg / mL.

[0011] Preferably, the benzimidazole compound containing thiol and carboxyl groups is 2-mercapto-5-benzimidazole carboxylic acid, with the molecular formula C8H6N2O2S and the structural formula as follows: .

[0012] The preferred 2-mercapto-5-benzimidazole carboxylic acid molecule (2M5BA) has a benzimidazole planar skeleton and a thiol functional group (C=S) and a carboxyl functional group (-COOH). It can form a strong hydrogen bond network with organic cations in perovskite to guide crystallization and form coordinate bonds with uncoordinated lead ions, thereby achieving the dual effects of crystallization regulation and defect passivation, thus stabilizing the photoactive phase of perovskite.

[0013] Preferably, the perovskite active material in the perovskite layer is an organic-inorganic hybrid perovskite FA. 0.85 Cs 0.05 MA 0.1 The PbI3 perovskite layer has a thickness of 750-850 nm. The cubic phase of the formamidinium-cesium-methylammonium perovskite exhibits high peak intensities in XRD, such as at 2θ=14° and 2θ=28°.

[0014] A second aspect of the present invention is to provide an application of the benzimidazole-modified perovskite layer described in the first aspect of the present invention in an inverted perovskite solar cell (inverted perovskite solar cell), wherein the inverted perovskite solar cell comprises a conductive substrate, a hole transport layer, a perovskite layer, a passivation layer, an electron transport layer, a hole blocking layer, and an electrode stacked sequentially, wherein the perovskite layer is a thin film modified with benzimidazole compounds containing thiol and carboxyl groups, and the concentration of the benzimidazole compounds containing thiol and carboxyl groups in the perovskite precursor solution is 0.05-0.2 mg / mL.

[0015] This inverted perovskite solar cell exhibits a power conversion efficiency of 27-28% and an open-circuit voltage of 1.18-1.20V under AM 1.5G standard solar conditions.

[0016] Preferably, the perovskite active material in the perovskite layer is an organic-inorganic hybrid perovskite, and the thickness of the perovskite layer is 750-850 nm.

[0017] Preferably, the hole transport layer comprises a nickel oxide film and a self-assembled monomolecular film, wherein the self-assembled monomolecular film is a film made of (4-(3,6-diphenyl-9H-carbazole-9-yl)butyl)phosphoric acid (Ph-4PACz) or (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz), and the thickness of the hole transport layer is 15-20 nm.

[0018] Preferably, the electron transport layer is a fullerene (C0)2. 60 The passivation layer is a mixed solution of 3-methylthio-1-propanamine hydroiodate and piperazine hydroiodate, with a thickness of 3-5 nm; the hole blocking layer is copper bath (BCP), with a thickness of 4-5 nm; the electrode is a silver electrode with a thickness of 100-120 nm.

[0019] Preferably, the conductive substrate is an indium tin oxide transparent conductive film (ITO).

[0020] Preferably, the preparation method of the inverted perovskite solar cell includes the following steps: S1: Pretreated conductive glass substrate; S2: Spin-coat the prepared nickel oxide aqueous dispersion onto a conductive glass substrate and anneal it to obtain a nickel oxide thin film layer in the hole transport layer; S3: Spin-coat the prepared self-assembled monomolecular solution onto the surface of the nickel oxide thin film layer and anneal it to obtain the self-assembled monomolecular thin film layer in the hole transport layer. S4: Spin-coat the prepared perovskite mixed solution containing thiol and carboxyl groups onto the surface of the self-assembled monolayer and anneal it to obtain the perovskite layer. S5: Spin-coat a passivation layer onto the surface of the perovskite layer and anneal it; S6: An electron transport layer and a hole blocking layer are deposited on the surface of the passivation layer, and then an electrode layer is deposited to obtain a perovskite solar cell.

[0021] Preferably, the perovskite layer in step S4 is prepared using a two-step spin-coating method, specifically: In an inert gas atmosphere (nitrogen, argon, etc.), benzimidazole compounds containing thiol and carboxyl groups are first added to a perovskite precursor solution made of perovskite active material in a certain proportion, and the mixture is then mixed to obtain a perovskite mixture. The perovskite mixture is then spin-coated onto the surface of a self-assembled monomolecular film at two spin speeds. After spin-coating is completed and a wet film is formed, an annealing treatment is performed to obtain a perovskite layer.

[0022] Preferably, the perovskite mixture is spin-coated in two steps: first, spin-coating at a first speed of 800-1000 rpm for 10 seconds, then spin-coating at a second speed of 4000-5000 rpm for 40 seconds, and adding 150-200 μL of ethyl acetate as a reverse solvent at the 35th second of spin-coating.

[0023] Preferably, the concentration of the perovskite mixture is 1.7-1.75 M, and the concentration of the benzimidazole compound containing thiol and carboxyl groups in the perovskite precursor solution is 0.05-0.2 mg / mL; the perovskite precursor solution is FA. 0.85 Cs 0.05 MA 0.1 The solution was a PbI3 perovskite solution, and the solvent used was a mixture of DMF and DMSO, with a volume ratio of DMF to DMSO of 8:(1.5-2.5).

[0024] Preferably, the perovskite precursor solution is prepared by dissolving 0.085 mmol CsI, 0.17 mmol MAI, 1.445 mmol FAI, 1.785 mmol PbI2, and 0.17 mmol MACl in 1 mL of a mixed solvent of DFM and DMSO (the volume ratio of DFM to DMSO is 8:2).

[0025] Preferably, the conductive glass is ITO conductive glass or FTO conductive glass.

[0026] Preferably, the method for preparing the inverted perovskite solar cell is characterized by comprising the following steps: S1. Treatment of ITO conductive glass: Wash the ITO conductive glass several times in sequence with detergent, deionized water, acetone and isopropanol, and then clean it with a UV ozone cleaner for 20-30 minutes. The cleaning treatment can improve the adhesion of the ITO conductive glass. S2. Preparation of nickel oxide thin film in hole transport layer: Dissolve 10-15 mg of nickel oxide nanoparticles in 1 mL of deionized water, and add 40 mol% hydrogen peroxide to promote dispersion. After shaking for 30 minutes, prepare nickel oxide aqueous dispersion solution. Drop the nickel oxide aqueous dispersion solution onto the cleaned ITO conductive glass, spin coat at 4000-6000 rpm, and then anneal at 140-160℃ for 10-20 minutes to obtain nickel oxide thin film in hole transport layer. S3. Preparation of self-assembled monomolecular thin film layer in hole transport layer: Prepare 0.001-0.002M solution of self-assembled monomolecular (4-(3,6-diphenyl-9H-carbazole-9-yl)butyl)phosphoric acid (Ph-4PACz) or (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz) using isopropanol as solvent; drop the above solution onto nickel oxide hole transport layer, spin coat at 5000-6000 rpm for 20-40 seconds, and then anneal at 100℃ for 5-10 minutes to obtain self-assembled monomolecular thin film layer in hole transport layer; The total thickness of the nickel oxide thin film and the self-assembled monomolecular thin film in the hole transport layer ranges from 15 to 20 nm. S4. Preparation of the perovskite layer (perovskite light-absorbing layer): S41 Preparation of perovskite precursor solution: Dissolve 0.085 mmol CsI, 0.17 mmol MAI, 1.445 mmol FAI, 1.785 mmol PbI2, and 0.17 mmol MACl in 1 mL of a mixed solvent of DFM and DMSO (the volume ratio of DFM to DMSO is 8:2) to obtain a perovskite precursor solution. S42 Preparation of perovskite mixed solution: Under an inert gas atmosphere, 2-mercapto-5-benzimidazole carboxylic acid is directly added to a 1.7-1.75M perovskite precursor solution, and 0.05-0.2 mg of 2M5BA is added per milliliter of perovskite precursor solution to obtain a perovskite mixed solution. S43 Preparation of Perovskite Layer: A perovskite mixed solution is dropped onto a self-assembled monomolecular hole transport layer, and spin-coated in two steps (800-1000 rpm for 10 seconds, 4000-5000 rpm for 40 seconds). 150-200 μL of ethyl acetate is added as an antisolvent at the 35th second of the spin-coating process. The resulting wet film is annealed at 100℃ for 10-30 minutes to obtain the perovskite layer. S5. Preparation of passivation layer: Using isopropanol as solvent, prepare a mixed solution of 2-3 mg / mL 3-methylthio-1-propanehydroiodate and 0.5-0.8 mg / mL piperazine hydroiodate, and spin-coat it onto the surface of the perovskite layer at 4000-5000 rpm, and anneal at 100℃ for 5 minutes to obtain a passivation layer with a thickness of 3-5 nm. S6. Fabrication of electron transport layer, hole blocking layer and electrode layer: 21-25 nm fullerene (C2) was deposited at a rate of 0.5 Å / s using a vacuum thermal evaporation system. 60 As an electron transport layer, 4-5 nm of bath copper ether (BCP) is deposited at a rate of 0.2 Å / s as a hole blocking layer, and 100-120 nm of silver is deposited at a rate of 0.8 Å / s as a metal electrode layer.

[0027] Compared with the prior art, the present invention has the following beneficial technical effects: (1) In view of the complexity of the crystallization process of perovskite in a multi-cationic system, this invention introduces benzimidazole compounds containing thiol and carboxyl groups in the process of preparing perovskite light absorption layer, and proposes a "gradient passivation and crystallization management" strategy based on multifunctional small molecule additives. By precisely controlling the amount of benzimidazole compounds added, the defects of perovskite layer are effectively passivated, non-radiative recombination loss is reduced, and the crystallization process of perovskite is finely controlled.

[0028] (2) The multi-site molecule 2M5BA with carboxyl group enhancement introduced in this invention simultaneously regulates the crystallization kinetics of perovskite and optimizes the homogenization distribution of film components, thereby effectively suppressing the generation of harmful PbI2 impurity phase and the separation of cation phase in the multi-component perovskite system.

[0029] (3) The 2M5BA molecules introduced in this invention form a top-to-bottom gradient distribution in the film, which enables it to play a dynamic regulatory role at different stages of crystallization, effectively managing the distribution and reactivity of PbI2 in the precursor solution, thereby significantly promoting the homogenization and crystallization of perovskite. The resulting perovskite film exhibits high crystal orientation, reduced lattice strain, and significantly improved bulk and interface uniformity.

[0030] (4) The interface contact between the functional layers of the inverted perovskite solar cell in this invention is good, which effectively reduces the interface resistance and improves the charge transfer efficiency, thereby improving the overall performance of the cell. The control strategy proposed in this invention has been experimentally verified to enable the power conversion efficiency of the ternary inverted perovskite solar cell to exceed 27% under AM 1.5G standard solar conditions, while the open circuit voltage range is 1.18-1.20V, and it maintains good operational stability under continuous illumination.

[0031] (5) The preparation method used in this invention is simple, highly reproducible, and has a wide range of raw material sources and low cost, which is conducive to large-scale industrial production. Attached Figure Description

[0032] 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. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the structure of the perovskite solar cell prepared according to the present invention; wherein: 1-ITO conductive glass substrate; 2-nickel oxide hole transport layer; 3-self-assembled monolayer; 4-perovskite layer; 5-passivation layer; 6-electron transport layer and hole blocking layer; 7-silver electrode layer; Figure 2A This is a scanning electron microscope (SEM) image of the perovskite layer obtained in Comparative Example 1 of the present invention. Figure 2B for Figure 2A SEM image of the cross-section of the perovskite layer in the image; Figure 2C This is a SEM image of the perovskite layer obtained in specific embodiment 1 of the present invention; Figure 2D for Figure 2C SEM image of the cross-section of the perovskite layer in the image; Figure 3 The images show the XRD patterns of the perovskite layers obtained in Specific Embodiment 1 and Comparative Embodiment 1 of the present invention. Figure 4A The image shows the GIXRD diagram of the upper and lower interfaces of the perovskite layer obtained in Comparative Example 1 of the present invention. Figure 4B The image shows the GIXRD diagram of the upper and lower interfaces of the perovskite layer obtained in specific embodiment 1 of the present invention. Figure 5A The image shows a time-of-flight secondary ion mass spectrometry (ToF-SIMS) image of the perovskite layer prepared in Comparative Example 1 of the present invention. Figure 5B This is a time-of-flight secondary ion mass spectrometry (ToF-SIMS) image of the perovskite layer obtained in specific embodiment 1 of the present invention; Figure 6A The image shows the AFM image of the perovskite layer obtained in Comparative Example 1 of the present invention. Figure 6B The image shown is an AFM image of the perovskite layer obtained in specific embodiment 1 of the present invention. Figure 7 The JV curves of the perovskite solar cells prepared in Specific Embodiment 2 and Comparative Embodiment 2 of the present invention are shown. Figure 8 The PCE spectra are for the long-term operational stability of the perovskite solar cells prepared in Specific Example 2 and Comparative Example 2 of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] In this document, "and / or" includes any and all combinations of one or more of the listed related items.

[0036] In this article, "multiple" means two or more, that is, it includes two, three, four, five, etc.

[0037] As used in this specification, the term "about" typically means + / -5% of the value, more typically + / -4%, more typically + / -3%, more typically + / -2%, even more typically + / -1%, and even more typically + / -0.5%.

[0038] In this specification, certain embodiments may be disclosed in a range-bound format. It should be understood that this "range-bound" description is merely for convenience and brevity and should not be construed as a rigid limitation on the disclosed range. Therefore, the description of a range should be considered as having specifically disclosed all possible subranges and the individual numerical values ​​within those ranges. For example, a description of the range 1-6 should be considered as having specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and the individual numbers within those ranges, such as 1, 2, 3, 4, 5, and 6. This rule applies regardless of the breadth of the range.

[0039] Definition of the noun: DFM: N,N-dimethylformamide; DMSO: Dimethyl sulfoxide.

[0040] Example: The benzimidazole-modified perovskite layer is a thin film modified with benzimidazole compounds containing thiol and carboxyl groups.

[0041] The benzimidazole compound containing thiol and carboxyl groups is a compound having a benzimidazole planar skeleton and having a thiol functional group (C=S) and a carboxyl functional group (-COOH). The concentration of the benzimidazole compound containing thiol and carboxyl groups in the perovskite precursor solution is 0.05-0.2 mg / mL.

[0042] In some specific embodiments, the benzimidazole compound containing thiol and carboxyl groups is 2-mercapto-5-benzimidazole carboxylic acid, with the molecular formula C8H6N2O2S and the structural formula as follows: .

[0043] The preferred 2-mercapto-5-benzimidazole carboxylic acid molecule (2M5BA) has a benzimidazole planar skeleton and a thiol functional group (C=S) and a carboxyl functional group (-COOH). It can form a strong hydrogen bond network with organic cations in perovskite to guide crystallization and form coordinate bonds with uncoordinated lead ions, thereby achieving the dual effects of crystallization regulation and defect passivation, thus stabilizing the photoactive phase of perovskite.

[0044] In some specific embodiments, the perovskite active material in the perovskite precursor solution is an organic-inorganic hybrid perovskite, and the thickness of the perovskite layer is 750-850 nm.

[0045] In some specific embodiments, the perovskite active material is FA. 0.85 Cs 0.05 MA 0.1The cubic phase of PbI3, formamidinium-cesium-methylammonium perovskite, exhibits high peak intensities in XRD, such as at 2θ=14° and 2θ=28°.

[0046] The application of the benzimidazole-modified perovskite layer in inverted perovskite solar cells (inverted perovskite solar cells) includes a conductive substrate, a hole transport layer, a perovskite layer, a passivation layer, an electron transport layer, a hole blocking layer, and an electrode stacked sequentially. The perovskite layer is a thin film modified with benzimidazole compounds containing thiol and carboxyl groups. The concentration of the benzimidazole compounds containing thiol and carboxyl groups in the perovskite precursor solution is 0.05-0.2 mg / mL.

[0047] This inverted perovskite solar cell exhibits a power conversion efficiency of 27-28% and an open-circuit voltage of 1.18-1.20V under AM 1.5G standard solar conditions.

[0048] In some specific embodiments, the perovskite active material in the perovskite layer is an organic-inorganic hybrid perovskite, and the thickness of the perovskite layer is 750-850 nm.

[0049] In some specific embodiments, the hole transport layer comprises a nickel oxide film and a self-assembled monomolecular film. The self-assembled monomolecular film is a self-assembled monomolecular film prepared from (4-(3,6-diphenyl-9H-carbazole-9-yl)butyl)phosphoric acid (Ph-4PACz) or (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz). The thickness of the hole transport layer is 15-20 nm. The self-assembled monomolecular film (such as Ph-4PACz) can form a dense hole transport layer, improving hole extraction efficiency and reducing interfacial recombination.

[0050] In some specific embodiments, the electron transport layer is a fullerene (C 60 The passivation layer is copper bath (BCP) with a thickness of 4-5 nm; the electrode is a silver electrode with a thickness of 100-120 nm.

[0051] In some specific embodiments, the conductive substrate is an indium tin oxide transparent conductive film (ITO).

[0052] In some specific embodiments, the preparation method of the inverted perovskite solar cell includes the following steps: S1: Pre-treated conductive glass substrate 1; S2: Spin-coat the prepared nickel oxide aqueous dispersion solution onto the conductive glass substrate 1 and anneal it to obtain the nickel oxide thin film layer in the hole transport layer; S3: Spin-coat the prepared self-assembled monomolecular solution onto the surface of the nickel oxide thin film layer and anneal it to obtain the self-assembled monomolecular thin film layer in the hole transport layer. S4: Spin-coat the prepared perovskite mixed solution containing thiol and carboxyl groups onto the surface of the self-assembled monomolecular thin film layer 3, and anneal it to obtain the perovskite layer 4. S5: Spin-coat passivation layer 5 onto the surface of the perovskite layer and anneal it; S6: An electron transport layer and a hole blocking layer 6 are deposited on the surface of the passivation layer 5, and then an electrode layer 7 is deposited to obtain a perovskite solar cell.

[0053] In some specific embodiments, the perovskite layer 4 in step S4 is prepared using a two-step spin-coating method, specifically as follows: In an inert gas atmosphere (nitrogen, argon, etc.), benzimidazole compounds containing thiol and carboxyl groups are first added to a perovskite precursor solution made of perovskite active material in proportion, and the mixture is then mixed to obtain a perovskite mixture. The perovskite mixture is then spin-coated onto the surface of a self-assembled monomolecular film at two spin speeds. After spin-coating is completed and a wet film is formed, annealing is performed to obtain perovskite layer 4.

[0054] In some specific embodiments, the perovskite mixture is spin-coated in two steps: first, spin-coating at a first speed of 800-1000 rpm for 10 seconds, then spin-coating at a second speed of 4000-5000 rpm for 40 seconds, and adding 150-200 μL of ethyl acetate as a reverse solvent at the 35th second of spin-coating.

[0055] In some specific embodiments, the concentration of the perovskite mixture is 1.7-1.75 M, and the concentration of the benzimidazole compound containing thiol and carboxyl groups in the perovskite precursor solution is 0.05-0.2 mg / mL; the perovskite precursor solution is FA. 0.85 Cs 0.05 MA 0.1 The solution was a PbI3 perovskite solution, and the solvent used was a mixture of DMF and DMSO, with a volume ratio of DMF to DMSO of 8:(1.5-2.5).

[0056] In some specific embodiments, the perovskite precursor solution was prepared by dissolving 0.085 mmol CsI, 0.17 mmol MAI, 1.445 mmol FAI, 1.785 mmol PbI2, and 0.17 mmol MACl in 1 mL of a mixed solvent of DFM and DMSO (DMF to DMSO volume ratio of 8:2).

[0057] In some specific embodiments, the conductive glass is ITO conductive glass or FTO conductive glass.

[0058] In some specific embodiments, the method for preparing this inverted perovskite solar cell is characterized by comprising the following steps: S1. Treatment of ITO conductive glass 1: Wash ITO conductive glass 1 several times in sequence with detergent, deionized water, acetone and isopropanol, and then clean it with a UV ozone cleaner for 20-30 minutes. Set aside for use. The cleaning treatment can improve the adhesion of ITO conductive glass 1. The detergent is a common detergent (such as dish soap), which is mainly used for the initial cleaning of oil stains on the surface of ITO conductive glass. S2. Preparation of nickel oxide hole transport layer 2: Dissolve 10-15 mg of nickel oxide nanoparticles in 1 mL of deionized water and add 40 mol% hydrogen peroxide to promote dispersion. After shaking for 30 minutes, prepare a nickel oxide aqueous dispersion solution. Drop the nickel oxide aqueous dispersion solution onto the cleaned ITO conductive glass 1 and spin-coat it at a speed of 4000-6000 rpm. Then anneal it at 140-160℃ for 10-20 minutes to obtain nickel oxide hole transport layer 2. S3. Preparation of self-assembled monomolecular hole transport layer: Using isopropanol as solvent, prepare a 0.001-0.002M solution of self-assembled monomolecular (4-(3,6-diphenyl-9H-carbazole-9-yl)butyl)phosphoric acid (Ph-4PACz) or (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz); drop the above solution onto nickel oxide hole transport layer 2, spin coat at 5000-6000 rpm for 20-40 seconds, and then anneal at 100℃ for 5-10 minutes to obtain self-assembled monomolecular hole transport layer 3; S4. Preparation of perovskite layer 4 (perovskite light-absorbing layer): S41 Preparation of perovskite precursor solution: Dissolve 0.085 mmol CsI, 0.17 mmol MAI, 1.445 mmol FAI, 1.785 mmol PbI2, and 0.17 mmol MACl in 1 mL of a mixed solvent of DFM and DMSO (the volume ratio of DFM to DMSO is 8:2) to obtain a perovskite precursor solution. S42 Preparation of perovskite mixed solution: Under an inert gas atmosphere (nitrogen, argon, etc.), 0.05-0.2 mg / mL of 2-mercapto-5-benzimidazole carboxylic acid is directly added to a 1.7-1.75 M perovskite precursor solution to obtain a perovskite mixed solution. S43 Preparation of perovskite layer: A perovskite mixed solution is dropped onto the self-assembled monomolecular hole transport layer 3, and spin-coated in two steps (800-1000 rpm for 10 seconds, 4000-5000 rpm for 40 seconds). 150-200 μL of ethyl acetate antisolvent is added at the 35th second of the spin-coating process. The resulting wet film is annealed at 100℃ for 10-30 minutes to obtain perovskite layer 4. S5. Preparation of passivation layer 5: Using isopropanol as solvent, prepare a mixed solution of 2-3 mg / mL 3-methylthio-1-propanehydroiodate and 0.5-0.8 mg / mL piperazine hydroiodate, and spin-coat it onto the surface of the perovskite layer at 4000-5000 rpm, and anneal at 100℃ for 5 minutes to obtain a passivation layer 5 with a thickness of 3-5 nm. S6. Fabrication of electron transport layer and electrode layer: 21-25 nm fullerene (C2) was deposited by vacuum thermal evaporation at a rate of 0.5 Å / s. 60 As an electron transport layer, 4-5 nm of bath copper ether (BCP) is deposited at a rate of 0.2 Å / s as a hole blocking layer, and 100-120 nm of silver is deposited at a rate of 0.8 Å / s as a metal electrode layer.

[0059] Specific Example 1: The benzimidazole-modified perovskite layer is a thin film modified with benzimidazole compounds containing thiol and carboxyl groups; the perovskite active material in the perovskite layer is FA. 0.85 Cs 0.05 MA 0.1 PbI3, wherein the benzimidazole compound containing thiol and carboxyl groups is a compound having a benzimidazole planar skeleton, and simultaneously possessing a thiol functional group (C=S) and a carboxyl functional group (-COOH), and the concentration of the benzimidazole compound containing thiol and carboxyl groups in the perovskite precursor solution is 0.1 mg / mL. The benzimidazole compound containing thiol and carboxyl groups is 2-mercapto-5-benzimidazole carboxylic acid, with the molecular formula C8H6N2O2S and the structural formula as follows: .

[0060] Comparative Example 1: Perovskite layer without modification by benzimidazole compounds, wherein the perovskite active substance in the perovskite layer is FA. 0.85 Cs 0.05 MA 0.1 PbI3.

[0061] The perovskite layer of Comparative Example 1 without the addition of 2-mercapto-5-benzimidazole carboxylic acid (2M5BA) and the perovskite layer with the addition of 2-mercapto-5-benzimidazole carboxylic acid were characterized.

[0062] from Figure 2A and Figure 2BThe topographic and cross-sectional views of Comparative Example 1 shown are as follows: Figure 2C and Figure 2D As shown in the morphology and cross-sectional images of Specific Example 1, the addition of 2M5BA significantly increases the grain size of the perovskite layer and reduces the number of grain boundaries. Specifically, in the 2M5BA-modified film, the visible PbI2 crystals completely disappear, attributed to 2M5BA effectively controlling the distribution of excess PbI2, causing it to be uniformly dispersed in the bulk phase of the film as a weakly crystalline mesophase or coordination complex. Cross-sectional SEM images further reveal the differences in the orderliness of crystal growth: the film without 2M5BA shows irregular, non-penetrating grain boundaries, indicating disorder in its crystallization process; while the film with 2M5BA exhibits clear, straight, and penetrating grain boundaries, suggesting highly ordered crystal growth.

[0063] like Figure 3 As shown, the perovskite layers prepared in Comparative Example 1 and Specific Example 1 were characterized by X-ray diffraction (XRD), wherein... Figure 3 The XRD pattern of Comparative Example 1 shows a distinct PbI2 crystalline phase. The intensity ratio and texture coefficient of the (100) or (200) crystal plane of the perovskite layer after adding 0.1 mg / mL of 2M5BA small molecules are significantly increased relative to the (110), (111) and (210) crystal planes. This indicates that the 2M5BA-doped film has a preferred growth characteristic along the {100} crystal plane family, which endows the film with excellent charge transport characteristics and reduced defect density, thereby improving the performance of photovoltaic devices.

[0064] like Figure 4A and Figure 4B As shown, the perovskite films of Comparative Example 1 and Specific Example 1 were characterized by grazing incidence X-ray diffraction (GIXRD), thus confirming the effect of the 2M5BA additive molecules on the residual strain of the perovskite films. This method analyzes the film strain by monitoring the change in the position of diffraction peaks of specific crystal phases with the X-ray incident tilt angle (Ψ). Figure 4A and Figure 4B It can be seen that as the Ψ angle increases from 10° to 50°, the characteristic diffraction peak of the (100) crystal plane of the perovskite layer in Comparative Example 1 shifts significantly towards higher angles, indicating that there is a large residual compressive strain in its bulk phase. In contrast, the (100) diffraction peak of the perovskite layer doped with 2M5BA in Specific Example 1 only shows a slight shift, indicating that the stress in the perovskite film doped with 2M5BA in Specific Example 1 is effectively released. The results obtained from the tests on the upper and lower surfaces of the film are consistent, which also confirms that the addition of 2M5BA achieves a homogenized stress distribution in the film.

[0065] Depth profiling analysis of perovskite thin films was performed using a time-of-flight secondary ion mass spectrometer (IONTOF M6). Analysis was conducted in dual-beam depth profiling mode. A bismuth trivalent ion beam (30 keV) was used as the primary ion source, exciting secondary ions from a 100 × 100 μm analytical region (128 × 128 pixels), with a mass detection range of 0-2000 atomic mass units. To minimize sputtering damage to organic molecules, depth profiling parameters were optimized for different analytes: the distribution characterization of the additive small molecule (2M5BA) was performed using a 10 keV argon cluster ion beam sputtering in an 800 × 800 μm region; simultaneously, the perovskite cation (FA... + MA + Cs + Pb + In + Ni + The distribution analysis was performed using a 1keV single-atom argon ion source for sputtering, with a sputtering area of ​​400 × 400 μm. Charge compensation was performed during the analysis using a low-energy electron diffuser. The acquired data were calibrated for surface potential and time-of-flight drift to finally generate a depth distribution map of the target ions. Figure 5A and Figure 5B As shown, the successful introduction of 2M5BA molecules into the perovskite film was confirmed by time-of-flight secondary ion mass spectrometry (TOF-SIMs). The distribution of various components in the perovskite layer was also obtained. The 2M5BA molecules exhibited a top-to-bottom gradient distribution in the film, and their introduction effectively suppressed the A-site cation (FA). + MA + Cs + ) and Pb + The non-uniform distribution in the vertical direction. The main reason for this homogeneous distribution is that the functional groups (thiol and carboxyl groups) of 2M5BA provide multi-site coordination ability: the thiol group (C=S) and the uncoordinated lead ion (Pb) 2+ The carboxyl group (-COOH) forms a strong coordination bond with an organic cation (such as FA). + Through hydrogen bond network interactions, the component migration of the precursor solution is dynamically regulated during crystallization, thereby suppressing cation segregation and the formation of PbI2 impurity phase.

[0066] like Figure 6A and Figure 6B The AFM tests of the perovskite layers in Comparative Example 1 and Specific Example 1 show that the introduction of the additive 2M5BA small molecule reduces the surface roughness of the perovskite layer film, with its root mean square (RMS) value decreasing from 17.7 nm in Comparative Example 1 to 14.3 nm in Specific Example 1. This means that the interface between the perovskite layer and the adjacent charge transport layer is smoother, which is beneficial for charge extraction and transport.

[0067] Specific Example 2: Application of the benzimidazole-modified perovskite layer in an inverted perovskite solar cell (inverted perovskite solar cell). The inverted perovskite solar cell comprises, in sequence, an ITO conductive glass substrate 1, a hole transport layer (nickel oxide thin film layer and self-assembled monomolecule thin film layer), a perovskite layer 4, a passivation layer 5, an electron transport layer and a hole blocking layer 6, and a silver electrode layer 7. The perovskite layer is a thin film modified with benzimidazole compounds containing thiol and carboxyl groups. The concentration of the benzimidazole compounds containing thiol and carboxyl groups in the perovskite precursor solution is 0.1 mg / mL. The specific steps for preparing the inverted perovskite solar cell are as follows: S1. Treatment of ITO conductive glass substrate 1: Wash ITO conductive glass 1 several times with detergent, deionized water, acetone and isopropanol, and then clean ITO conductive glass 1 for 25 minutes with a UV ozone cleaner. S2. Preparation of nickel oxide thin film layer in hole transport layer: Dissolve 10mg of nickel oxide nanoparticles in 1mL of deionized water, and add 40mol% hydrogen peroxide as a base of nickel oxide aqueous solution to promote dispersion. After shaking for 30 minutes, prepare nickel oxide aqueous dispersion solution; drop the dispersion onto the cleaned ITO conductive glass 1, spin coat at 5000 rpm, and then anneal at 150℃ for 10 minutes. S3. Preparation of self-assembled monomolecular thin film layer in hole transport layer: Prepare 0.001-0.002M solution of self-assembled monomolecular ((4-(3,6-diphenyl-9H-carbazole-9-yl)butyl)phosphoric acid (Ph-4PACz) using isopropanol as solvent; drop the above solution onto nickel oxide thin film layer in hole transport layer, spin coat at 5000 rpm for 30 seconds, anneal at 100℃ for 10 minutes, thereby obtaining self-assembled monomolecular hole transport layer 3; S4. Preparation of perovskite layer 4 (perovskite light-absorbing layer): S41 Preparation of perovskite precursor solution: Dissolve 0.085 mmol CsI, 0.17 mmol MAI, 1.445 mmol FAI, 1.785 mmol PbI2, and 0.17 mmol MACl in 1 mL of a mixed solvent of DFM and DMSO (the volume ratio of DFM to DMSO is 8:2) to obtain a perovskite precursor solution. S42 Preparation of perovskite mixed solution: Under an inert gas atmosphere (nitrogen, argon, etc.), 0.05 mg / mL (the concentration of 2M5BA in the perovskite precursor solution) of 2-mercapto-5-benzimidazole carboxylic acid (2M5BA) is directly added to the perovskite precursor solution to obtain a perovskite mixed solution. S43 Preparation of perovskite layer 4: A perovskite mixed solution was dropped onto the self-assembled monomolecular hole transport layer 3, and spin-coated in two steps (1000 rpm for 10 seconds and 5000 rpm for 40 seconds). 170 μL of ethyl acetate antisolvent was dropped on the 35th second of the spin-coating process. The resulting wet film was annealed at 100 °C for 10 minutes to obtain perovskite layer 4. S5. Preparation of passivation layer 5: Using isopropanol as solvent, prepare a mixed solution of 2.8 mg / mL 3-methylthio-1-propanehydroiodate and 0.7 mg / mL piperazine hydroiodate, and spin-coat it onto the surface of the perovskite layer at 4000-5000 rpm, and anneal at 100℃ for 5 minutes to obtain passivation layer 5. S6. Fabrication of the electron transport layer and electrode layer: 24 nm fullerene (C2) was deposited at a rate of 0.5 Å / s using a vacuum thermal evaporation system. 60 As an electron transport layer, 4 nm of bath copper ether (BCP) was deposited at a rate of 0.2 Å / s as a hole blocking layer, and 120 nm of silver was deposited at a rate of 0.8 Å / s as a metal electrode layer.

[0068] like Figure 7 The figures show the forward and reverse JV curves of the perovskite solar cells prepared in Comparative Example 2 and Specific Example 2. Testing revealed that, compared to Comparative Example 2, the perovskite solar cell prepared in Specific Example 2, with the addition of the 2M5BA molecule, showed an increase in Voc from 1.182V to 1.196V and a Jsc from 26.03mA / cm². 2 Increased to 26.37 mA / cm 2 The FF increased from 83.42% to 86.31%, and the final device photoelectric conversion efficiency increased from 25.66% to 27.22%.

[0069] like Figure 8 The figure shows the PCE spectra of the perovskite solar cells prepared in Comparative Example 2 and Specific Example 2, indicating their long-term operational stability. Tests showed that the perovskite solar cell prepared in Specific Example 2, compared to Comparative Example 2, exhibited significantly improved final device stability with the addition of the 2M5BA molecule. After 1500 hours of testing, the efficiency of the perovskite solar cell without the 2M5BA molecule decreased to below 80% of its initial efficiency, while the perovskite solar cell with the 2M5BA molecule maintained an initial efficiency of over 90%. Specifically, the introduction of the 2M5BA molecule, through its enhanced multi-site coordination ability via its carboxyl groups, effectively regulated the crystallization process of the perovskite, suppressing the formation of harmful PbI2 impurity phases and cation phase separation. This resulted in a thin film with higher crystal orientation, lower lattice strain, and more uniform bulk and interface phases, significantly improving the operational stability of the perovskite solar cell.

[0070] Specific Example 3: The difference from Specific Example 1 is that the amount of 2-mercapto-5-benzimidazole carboxylic acid (2M5BA) added is 0.05 mg / mL (the molar ratio of 2M5BA to Pb in the perovskite precursor solution).

[0071] Specific Example 4: The difference from Specific Example 1 is that the amount of 2-mercapto-5-benzimidazole carboxylic acid (2M5BA) added is 0.15 mg / mL (the molar ratio of 2M5BA to Pb in the perovskite precursor solution).

[0072] Specific Example 5: The difference from Specific Example 1 is that the amount of 2-mercapto-5-benzimidazole carboxylic acid (2M5BA) added is 0.2 mg / mL (the molar ratio of 2M5BA to Pb in the perovskite precursor solution).

[0073] Comparative Example 2: The difference from Specific Example 2 is that no 2M5BA small molecule was added during the preparation of the perovskite layer in step S4. The specific preparation method is as follows: Under an inert gas atmosphere (nitrogen, argon, etc.), 1.7 M perovskite (FA) 0.85 Cs 0.05 MA 0.1 PbI3 solution (DMF:DMSO volume ratio of 8:2) was dropped onto the self-assembled monomolecular hole transport layer and spin-coated in two steps (1000 rpm for 10 seconds and 5000 rpm for 40 seconds). 170 μL of ethyl acetate was added as an antisolvent at the 35th second of the spin-coating process. The wet film was then annealed at 100 °C for 10 minutes.

[0074] The performance test results of the inverted perovskite solar cells prepared in Comparative Example 2 and Specific Examples 2-5 are shown in Table 1.

[0075] Table 1. Performance results of inverted perovskite solar cells in Comparative Example 2 and Specific Examples 2-5 As shown in Table 1, the inverted perovskite solar cell exhibited the best performance when the concentration of 2M5BA small molecule was 0.1 mg / mL, with an open-circuit voltage (Voc) of 1.196 V, a short-circuit current density (Jsc) of 26.37 mA / cm², a fill factor (FF) of 86.31%, and a power conversion efficiency (PCE) of 27.22%. This performance is significantly better than that of the perovskite solar cell without 2M5BA (Comparative Example 2, PCE 25.66%) and other cells with different molar ratios of 2M5BA small molecule addition. When the concentration of 2M5BA small molecule was 0.05 mg / mL, the cell performance also improved, but the improvement was not as significant as at 0.1 mg / mL. However, when the concentration of 2M5BA small molecule increased to 0.15 mg / mL and 0.2 mg / mL, the perovskite cell performance actually decreased to some extent. This may be due to the excessively high additive concentration causing some degree of damage to the perovskite layer structure or a reduction in charge transport efficiency. Therefore, this result confirms that adding an appropriate amount of 2M5BA small molecules can significantly improve the performance of inverted perovskite solar cells, and the optimal addition amount should be 0.1 mg / mL.

[0076] Specific Example 6: The difference from Specific Example 2 is that the annealing temperature for preparing the perovskite layer in step S4 is 90°C.

[0077] Specific Example 7: The difference from Specific Example 2 is that the annealing temperature for preparing the perovskite layer in step S4 is 110°C.

[0078] The perovskite solar cells prepared in Specific Examples 2 and 6-7 were subjected to performance tests, and the test results are shown in Table 2.

[0079] Table 2 shows the performance results of the inverted perovskite solar cells in specific embodiments 2 and 6-7. As can be seen from the test results in Table 2, the annealing temperature has a significant impact on the performance of perovskite solar cells. In Specific Example 2, when the annealing temperature is set to 100℃, the perovskite cell exhibits the best performance, with an open-circuit voltage (Voc) of 1.196V, a short-circuit current density (Jsc) of 26.37mA / cm², a fill factor (FF) of 86.31%, and a power conversion efficiency (PCE) of 27.22%. In contrast, when the annealing temperature is reduced to 90℃ (Specific Example 6), the performance of the perovskite cell decreases, with its PCE dropping to 26.37%. When the annealing temperature is increased to 110℃ (Specific Example 7), the performance of the perovskite cell further decreases, with a PCE of only 26.11%. These test results indicate that excessively high or low annealing temperatures are detrimental to the performance of perovskite solar cells. An annealing temperature of 100℃ ensures good crystallization of the perovskite layer while avoiding damage to the cell structure from high temperatures or incomplete crystallization caused by low temperatures.

[0080] The thiol and carboxyl groups in 2M5BA of this invention provide unique coordination and hydrogen bonding capabilities, achieving synergistic effects of bulk defect passivation and crystallization regulation; the self-assembled monomolecular film provides a good interfacial foundation and has a synergistic effect with 2M5BA, thereby enabling the self-assembled monomolecular film to more effectively transport holes and avoid interfacial loss after the perovskite bulk phase quality is optimized with 2M5BA small molecules.

[0081] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0082] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A benzimidazole-modified perovskite layer, characterized in that, The perovskite layer is a thin film modified with benzimidazole compounds containing thiol and carboxyl groups.

2. The benzimidazole-modified perovskite layer according to claim 1, characterized in that, The benzimidazole compound containing thiol and carboxyl groups is a compound having a benzimidazole planar skeleton and having a thiol functional group (C=S) and a carboxyl functional group (-COOH); the concentration of the benzimidazole compound containing thiol and carboxyl groups in the perovskite precursor solution is 0.05-0.2 mg / mL.

3. The benzimidazole-modified perovskite layer according to claim 1, characterized in that, The benzimidazole compound containing thiol and carboxyl groups is 2-mercapto-5-benzimidazole carboxylic acid, with the molecular formula C8H6N2O2S and the structural formula as follows: 。 4. The benzimidazole-modified perovskite layer according to claim 1, characterized in that, The perovskite active material in the perovskite layer is an organic-inorganic hybrid perovskite FA. 0.85 Cs 0.05 MA 0.1 PbI3.

5. The application of a benzimidazole-modified perovskite layer according to any one of claims 1-4 in an inverted perovskite solar cell, characterized in that, The inverted perovskite solar cell comprises a conductive substrate, a hole transport layer, a perovskite layer, a passivation layer, an electron transport layer, a hole blocking layer, and an electrode stacked sequentially. The perovskite layer is a thin film modified with benzimidazole compounds containing thiol and carboxyl groups, and the concentration of the benzimidazole compounds containing thiol and carboxyl groups in the perovskite precursor solution is 0.05-0.2 mg / mL.

6. The application of the benzimidazole-modified perovskite layer according to claim 4 in an inverted perovskite solar cell, characterized in that, The hole transport layer comprises a nickel oxide film and a self-assembled monomolecular film. The self-assembled monomolecular film is a film made of (4-(3,6-diphenyl-9H-carbazole-9-yl)butyl)phosphonic acid or (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid. The thickness of the hole transport layer is 15-20 nm.

7. The application of the benzimidazole-modified perovskite layer according to claim 6 in an inverted perovskite solar cell, characterized in that, The specific steps for preparing the inverted perovskite solar cell are as follows: S1: Pretreated conductive glass substrate; S2: Spin-coat the prepared nickel oxide aqueous dispersion onto a conductive glass substrate and anneal it to obtain a nickel oxide thin film layer in the hole transport layer; S3: Spin-coat the prepared self-assembled monomolecular solution onto the surface of the nickel oxide thin film layer and anneal it to obtain the self-assembled monomolecular thin film layer in the hole transport layer. S4: Spin-coat the prepared perovskite mixed solution containing thiol and carboxyl groups onto the surface of the self-assembled monolayer and anneal it to obtain the perovskite layer. S5: Spin-coat a passivation layer onto the surface of the perovskite layer and anneal it; S6: An electron transport layer is deposited on the surface of the passivation layer, and then an electrode layer is deposited to obtain an inverted perovskite solar cell.

8. The application of the benzimidazole-modified perovskite layer according to claim 6 in an inverted perovskite solar cell, characterized in that, The perovskite layer in step S4 is prepared using a two-step spin-coating method, specifically: In an inert gas atmosphere, benzimidazole compounds containing thiol and carboxyl groups are first added in proportion to a perovskite precursor solution made of perovskite active material, and the mixture is then mixed to obtain a perovskite mixture. The perovskite mixture is then spin-coated onto the surface of a self-assembled monomolecular film at two spin speeds. After spin-coating is completed and a wet film is formed, annealing is performed to obtain a perovskite layer.

9. The application of the benzimidazole-modified perovskite layer according to claim 8 in an inverted perovskite solar cell, characterized in that, In step S4, the perovskite mixture is spin-coated in two steps at different speeds: first, spin-coating at a first speed of 800-1000 rpm for 10 seconds, then spin-coating at a second speed of 4000-5000 rpm for 40 seconds, and adding 150-200 μL of ethyl acetate as a reverse solvent at the 35th second of spin-coating.

10. The application of the benzimidazole-modified perovskite layer according to claim 8 in an inverted perovskite solar cell, characterized in that, In step S4, the concentration of the perovskite mixture is 1.7-1.75 M, and the concentration of the benzimidazole compound containing thiol and carboxyl groups in the perovskite precursor solution is 0.05-0.2 mg / mL; the perovskite precursor solution is FA. 0.85 Cs 0.05 MA 0.1 The solution was a PbI3 perovskite solution, and the solvent used was a mixture of DMF and DMSO, with a volume ratio of DMF to DMSO of 8:(1.5-2.5).

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