Interface modification layer comprising fluorine-containing small-molecular organic matter and preparation method and application of interface modification layer

Abstract

The invention provides an interface modification layer containing a fluorine-containing small-molecular organic matter and a preparation method and application thereof, the interface modification layer is located between a hole transport layer and a metal electrode of a perovskite solar cell, and the interface modification layer comprises the fluorine-containing small-molecular organic matter. According to the invention, an interface modification layer with chemical inertness, strong reaction shielding capability and ion migration blocking is designed and constructed between the HTL and the metal electrode of the perovskite solar cell, and the interface modification material can be used for constructing a stable hole transport layer / metal electrode interface.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and more particularly to an interface modification layer comprising fluorine-containing small molecule organic matter, its preparation method and application, and a perovskite solar cell comprising the interface modification layer. Background Technology

[0002] Solar photovoltaic technology is one of the most promising forms of large-scale clean energy. With continuous improvements in device efficiency, perovskite solar cells have become a research hotspot in the photovoltaic field due to their advantages such as high light absorption coefficient, solution-processability, and low cost. In recent years, the photoelectric conversion efficiency of perovskite cells has approached that of mature technologies such as crystalline silicon, demonstrating commercial viability.

[0003] In conventional nip-structure perovskite solar cells, the hole transport layer (HTL) is one of the key layers determining charge extraction efficiency and interfacial stability. In nip structures, commonly used organic HTLs, such as Spiro-OMeTAD, PTAA (polytriphenylamine), and polymeric small-molecule hole materials, are the mainstream choice for achieving high-efficiency perovskite devices. For the electrode portion of the device, commonly used metal electrodes include silver (Ag), gold (Au), and copper (Cu). The interaction between the metal electrode and the HTL is currently one of the most critical factors leading to insufficient device stability. Although the stability of the perovskite material itself has been improved to some extent through strategies such as compositional control and grain boundary passivation, the overall device lifetime is still severely limited by chemical reactions at the electrode interface, metal ion migration, and HTL system degradation. Therefore, improving the chemical and physical stability of the HTL / metal electrode interface is currently the core challenge for the commercialization of perovskite solar cells.

[0004] In typical nip-structured perovskite solar cells, the organic hole transport layer (HTL), such as Spiro-OMeTAD, PTAA, and other polymeric hole materials, is usually in direct contact with the metal electrode (such as Ag, Au, and Al). This interface is considered a critical weak point where physical and chemical degradation is most likely to occur during device operation. Numerous studies have shown that direct contact between the metal electrode and the organic HTL triggers complex interfacial reactions and diffusion behaviors, severely affecting device stability and long-term lifetime. The metal electrode can undergo interfacial chemical reactions with doped organic HTLs. For example, Spiro-OMeTAD doped with Li-TFSI or TBP readily produces unstable reaction products such as Ag–TFSI when in contact with a metal. Au electrodes may also react with HTLs under bias or illumination conditions, and the surface properties of the metal may catalyze the decomposition or oxidation of the HTL. These interfacial reactions disrupt the conductivity and energy level structure of the HTL and introduce non-radiative recombination centers, leading to a continuous decline in device performance and lifetime.

[0005] Furthermore, under conditions of light, electric field, or thermal stress, metal ions such as Ag in the metal electrode... + Au + Migration occurs along the pores of the HTL, local vacancies caused by dopants, or intersegmental gaps. This irreversible diffusion leads to the redistribution and aggregation of dopants, causing changes in the local energy levels of the HTL, and even causing metal to form clusters at the interface or penetrate the HTL into the perovskite layer, triggering more severe decomposition reactions. This is considered one of the main mechanisms of rapid degradation in perovskite solar cells. Meanwhile, commonly used doping systems in organic HTLs, such as Li-TFSI and TBP, have limited inherent stability and are prone to migration or decomposition. The metal electrode further accelerates this degradation process, for example, by promoting the degradation of Li... + Migration and accumulation toward the metal, or induction of TFSI - Decomposition on the metal surface produces unstable byproducts. These processes all impair the conductivity and interfacial contact quality of the HTL, ultimately leading to a decrease in device voltage and fill factor.

[0006] Because current mainstream device structures generally adopt a direct contact form between HTL and metal electrodes, they lack an interface modification layer that can effectively block chemical reactions and ion migration. The diffusion path of the metal is completely exposed, interface reactions are difficult to suppress, and the doped system is in a state of uncontrolled migration. Under actual operating conditions such as thermal aging, high light intensity operation, or applied bias voltage, such unprotected interfaces will degrade rapidly, making it difficult for devices to meet the long-term stability requirements for commercialization.

[0007] In perovskite solar cells, typical organic hole transport layers (HTLs) such as Spiro-OMeTAD and PTAA exhibit excellent hole transport performance and interface energy level matching in their initial state, ensuring high open-circuit voltage and fill factor. However, when these organic HTLs are in direct contact with metal electrodes such as silver and gold, and operate under illumination, thermal stress, or bias conditions, a series of chemical reactions and ion migration phenomena occur at the interface, leading to a rapid degradation of the HTL's conductivity, energy level structure, and interface stability. For example, metallic Ag readily reacts with TFSI in the HTL-doped system at the interface. - Unstable complexes form during the reaction, and the Au electrode reacts with the organic HTL under an applied bias voltage. Furthermore, the metal surface may catalyze the decomposition of the HTL. With prolonged operation, metal ions migrate further along the internal pores and intersegmental gaps of the HTL, causing dopant imbalance, interfacial energy level disturbances, and even metal cluster formation. These adverse processes ultimately lead to a decrease in device open-circuit voltage, an increase in series resistance, and an increase in trapped state density, making it difficult for perovskite solar cells to meet application requirements in real-world operating environments in terms of stability and lifetime.

[0008] Although academia and industry have recognized the importance of interfacial instability between metal electrodes and organic hole transport layers in recent years and have proposed several improvement schemes, most of these schemes focus on inorganic interface layers or inert covering materials. The solutions to the problems of chemical reactions, ion migration and degradation of doped systems between organic HTLs and metal electrodes are still not systematic enough.

[0009] Existing research has mainly attempted to add metal oxides (such as MoO3, NiO) between the HTL and the metal electrode. x Various methods are employed to reduce metal electrode corrosion or suppress Ag / Au diffusion, such as using metal interlayers (e.g., Bi, Pt) or electrically insulating polymers (e.g., PMMA, PEIE). For example, some literature reports that ultrathin MoO3 can improve the reflectivity of the Spiro-OMeTAD / Ag interface and delay electrode corrosion, while studies have shown that Bi metal interlayers can reduce metal reactions and improve device stability. Furthermore, some patents propose depositing PbS, ultrathin oxides, or carbon materials on top of HTLs as buffer layers. These approaches improve interface stability to some extent, but generally have the following limitations: First, inorganic oxide layers typically require vacuum evaporation or energy-intensive processes, which are unfavorable for large-area fabrication. Furthermore, their rigid structure does not readily match the interface of flexible organic HTLs, easily leading to interfacial hole blocking effects. Second, some metal interlayers themselves possess high chemical reactivity and may still react with HTLs or dopants. For example, Ag and Au readily react with TFSI-containing... -Spiro-OMeTAD forms unstable complexes, failing to fundamentally solve the interfacial reaction problem. Furthermore, most traditional polymer buffer layers are "physical covering" materials, lacking directional adsorption capabilities and the ability to inhibit metal ion migration, and are also ineffective for HTL-doped systems (Li). + TFSI - The migration behavior of ) is regulated.

[0010] Existing organic interface materials are mostly inert coatings (such as PMMA or simple polymers), lacking directional functional groups, unable to form specific interactions with metal electrodes, and also lacking the ability to construct dense cross-linked networks to block metal ion migration. Therefore, these materials cannot simultaneously meet the key requirements of: blocking metal ion diffusion, inhibiting HTL dopant migration, preventing interfacial chemical reactions, maintaining hole transport efficiency, solution processability, and low-cost preparation.

[0011] In summary, although existing technologies have attempted to improve the stability of the HTL / metal electrode interface through the interface layer, these solutions are either limited by material types (mainly inorganic and inert polymers) or lack targeted molecular design, and cannot simultaneously achieve multiple functions such as interface chemical stability, ion migration blocking, and doping system maintenance. Summary of the Invention

[0012] To address the issue of a significant decrease in interfacial stability of the hole transport layer after contact with a metal electrode, this invention proposes an interfacial modification material based on the reaction between organic small molecules and the metal interface, which is used to construct a stable hole transport layer / metal electrode interface by redesigning the molecular structure of the interfacial layer material.

[0013] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A first aspect of the present invention provides an interface modification layer located between the hole transport layer and the metal electrode of a perovskite solar cell, the interface modification layer comprising a fluorine-containing small molecule organic compound.

[0014] The perovskite solar cell described in this invention refers to a nip structure perovskite solar cell.

[0015] The fluorinated small-molecule organic compounds described in this invention refer to non-polymerized organic molecules containing at least one carbon-fluorine (CF) bond. Typically, their molecular weight is no greater than 1000 Da, preferably no greater than 800 Da, and more preferably no greater than 500 Da. Examples may include: perfluorinated compounds, fluorinated alkanes, fluorinated unsaturated hydrocarbons, fluorinated aromatic compounds, or fluorinated derivatives with functional groups (e.g., trifluoroacetic acid, pentafluorophenol, etc.).

[0016] After research, the inventors of this invention discovered that the fluorine element in the fluorine-containing small molecule organic compound included in the interface modification layer has high electronegativity, which can reduce the surface energy of the material and enhance the hydrophobicity of the interface; the C–F bonds in the molecule can interact directionally with the HTL surface to form a dense arrangement; fluorine atoms can regulate the interface energy level and improve the hole extraction capability without sacrificing the initial efficiency; the fluorine-containing small molecule organic compound in the interface modification layer can form an ultra-thin dense film at the interface, reducing the chemical contact between Ag and HTL dopants.

[0017] Those skilled in the art will understand that, based on the technical mechanism of action of the above-mentioned fluorinated small molecule organic compounds, the fluorinated small molecule organic compounds and their specific chemical structures can be adapted and designed according to solubility, energy level matching and polarity, without affecting the core technical effect of the interface modification layer of the present invention.

[0018] The interface modification layer of the present invention can significantly suppress Ag + Au + The diffusion behavior of metal ions reduces the doping system (Li) in HTL. + / TFSI - The perovskite molecules migrate toward the electrode direction, ultimately significantly improving the stability of perovskite devices (such as perovskite solar cells) under thermal stress, light stress, and bias conditions.

[0019] In some embodiments of the present invention, the fluorinated small molecule organic compound is selected from naphthane perfluorinated ion exchange resin (perfluorinated resin, Nafion, CAS No. 31175-20-9, with the molecular formula C9HF). 17 One or more of the following: O5S, small molecules containing perfluoroalkyl side chains, and small molecules containing polyfluorinated substituted aromatic ring structures.

[0020] In some embodiments of the present invention, the small molecule containing a perfluoroalkyl side chain is selected from perfluoroalkyl sulfonic acid, perfluoroalkyl phosphonic acid, perfluoroalkyl carboxylic acid or perfluoroalkyl thiol, wherein the alkyl group of the small molecule containing the perfluoroalkyl side chain can be butane, hexane or decane, for example, perfluoroalkyl sulfonic acid can be perfluorobutane sulfonic acid, perfluorohexane sulfonic acid or perfluorodecane sulfonic acid.

[0021] In some embodiments of the present invention, the small molecule containing a polyfluorinated substituted aromatic ring structure is selected from organic compounds containing polyfluorinated aryl sulfonic acids, organic compounds containing polyfluorinated aryl carboxylic acids, organic compounds containing polyfluorinated aryl phosphonic acids, or organic compounds containing polyfluorinated aryl thiols. Specifically, the organic compounds containing polyfluorinated aryl sulfonic acids may be 2,3,4,5,6-pentafluorobenzenesulfonic acid or 4-(trifluoromethyl)benzenesulfonic acid; the organic compounds containing polyfluorinated aryl carboxylic acids may be 2,3,4,5,6-pentafluorobenzoic acid or 4-(trifluoromethyl)benzoic acid; the organic compounds containing polyfluorinated aryl phosphonic acids may be 2,3,4,5,6-pentafluorobenzenephosphonic acid; and the organic compounds containing polyfluorinated aryl thiols may be pentafluorobenzene-1-thiol.

[0022] In some embodiments of the present invention, the interface modification layer is formed by spin-coating an interface solution containing a fluorinated small molecule organic compound. Isopropanol (IPA) and / or anhydrous ethanol (EtOH) can be used as solvents for the interface solution. When the interface modification layer is formed by spin-coating, the solvent will essentially evaporate completely.

[0023] In some embodiments of the present invention, the thickness of the interface modification layer is 1~20nm, preferably 3~8nm.

[0024] To address the issues of significantly reduced interface stability and insufficient lifetime of the hole transport layer in existing perovskite solar cells after contact with metal electrodes, this invention proposes innovative solutions to the following three technical problems: 1. Instability issues caused by interfacial chemical reactions: In existing technologies, there is a strong tendency for chemical reactions to occur between the metal electrode (such as silver or gold) and the hole transport layer, especially under thermal or electrical stress conditions. This interfacial reaction not only damages the interfacial layer structure but also induces the degradation of the perovskite active layer, severely limiting the stability and lifespan of the device. This invention introduces an interfacial modification layer with chemical inertness or reaction-shielding function between the hole transport layer and the metal electrode, effectively blocking this interfacial reaction and stabilizing the electrode-hole transport layer interface.

[0025] 2. Metal ion migration leading to device performance degradation: During long-term operation, existing devices experience metal ion migration (such as Ag) in the metal electrodes. + Au + Metal ions readily migrate to the hole transport layer or perovskite layer, causing problems such as charge transport imbalance, interface energy level changes, and doping system failure. This migration not only leads to rapid performance degradation but may also trigger irreversible device failure. The interface modification layer proposed in this invention can serve as an effective barrier against ion migration, preventing the diffusion of metal ions and synergistically suppressing dopants (such as Li) + TFSI - I - (etc.) migration, thereby significantly improving the long-term stability and reliability of the device.

[0026] 3. The problem of lack of an effective barrier layer at the HTL / metal contact interface: Traditional device structures generally lack functional interface layers, resulting in overly simplistic interface designs for perovskite solar cells that cannot meet the lifespan and stability requirements of industrial applications. This invention introduces a functional interface modification layer to enhance the thermal stability, humidity resistance, and electrochemical stability of the device while ensuring charge transport efficiency, providing a reliable structural foundation for the commercialization of high-performance perovskite solar cells.

[0027] A second aspect of the present invention provides a method for preparing the above-mentioned interface modification layer, comprising the steps of: S1. An interfacial solution containing the fluorine-containing small molecule organic compound is prepared. S2. The interface solution is used to form the interface modification layer by solution spin coating.

[0028] In some embodiments of the present invention, the fluorinated small molecule organic compound is selected from naphthane perfluorinated ion exchange resin (perfluorinated resin, Nafion, CAS No. 31175-20-9, with the molecular formula C9HF). 17 One or more of the following: O5S, small molecules containing perfluoroalkyl side chains, and small molecules containing polyfluorinated substituted aromatic ring structures.

[0029] In some embodiments of the present invention, the small molecule containing a perfluoroalkyl side chain is selected from perfluoroalkyl sulfonic acid, perfluoroalkyl phosphonic acid, perfluoroalkyl carboxylic acid or perfluoroalkyl thiol, wherein the alkyl group of the small molecule containing the perfluoroalkyl side chain can be butane, hexane or decane, for example, perfluoroalkyl sulfonic acid can be perfluorobutane sulfonic acid, perfluorohexane sulfonic acid or perfluorodecane sulfonic acid.

[0030] In some embodiments of the present invention, the small molecule containing a polyfluorinated substituted aromatic ring structure is selected from organic compounds containing polyfluorinated aryl sulfonic acids, organic compounds containing polyfluorinated aryl carboxylic acids, organic compounds containing polyfluorinated aryl phosphoric acids, or organic compounds containing polyfluorinated aryl thiols. Among them, the organic compounds containing polyfluorinated aryl sulfonic acids may be 2,3,4,5,6-pentafluorobenzenesulfonic acid or 4-(trifluoromethyl)benzenesulfonic acid, the organic compounds containing polyfluorinated aryl carboxylic acids may be 2,3,4,5,6-pentafluorobenzoic acid or 4-(trifluoromethyl)benzoic acid, the organic compounds containing polyfluorinated aryl phosphonic acids may be 2,3,4,5,6-pentafluorophenylphosphonic acid, and the organic compounds containing polyfluorinated aryl thiols may be pentafluorobenzene-1-thiol.

[0031] In some embodiments of the present invention, in step S1, the solvent of the interface solution is isopropanol (IPA) and / or anhydrous ethanol (EtOH).

[0032] In some embodiments of the present invention, the concentration of fluorine-containing small molecule organic compounds in the interfacial solution is 1-50 mg / mL, preferably 5-20 mg / mL, and more preferably 6-14 mg / mL.

[0033] In some embodiments of the present invention, in step S2, the spin coating speed of the solution spin coating method is 4000~6000 rpm, and the spin coating time is 20~40 seconds.

[0034] In this invention, when the interface modification layer is prepared by solution spin coating, the solvent will almost completely evaporate.

[0035] In this invention, the interface solution can be filtered before spin coating to remove large particles or impurities from the solution and reduce their impact on the experimental results.

[0036] In some embodiments of the present invention, the thickness of the interface modification layer is 1~20nm, preferably 3~8nm.

[0037] This invention employs a low-temperature solution spin-coating method to prepare an interface modification layer with a thickness controllable between 1 and 20 nm. The resulting interface modification layer is not only dense and continuous but also exhibits excellent wettability and molecular compatibility with HTL surfaces, thereby preventing hole blockage. This ensures that the invention is compatible with industrial-scale processes and possesses extremely high application value.

[0038] A third aspect of the present invention provides the application of the interface modification layer as described above or the interface modification layer prepared by the above method in perovskite solar cells.

[0039] A fourth aspect of the present invention provides a perovskite solar cell comprising the interface modification layer as described above or the interface modification layer prepared by the above method.

[0040] In some embodiments of the present invention, the perovskite solar cell includes a conductive substrate, an electron transport layer (ETL), a perovskite absorber layer, a hole transport layer (HTL), the interface modification layer, and a metal electrode, arranged sequentially. That is, the perovskite solar cell is a nip-structured perovskite solar cell.

[0041] In some embodiments of the present invention, the electron transport layer (ETL) may be, for example, TiO2, SnO2, or ZnO, but the present invention is not limited thereto. The perovskite absorber layer (PVK absorber layer) may be composed of FAPbI3 or MAPbI3, but the present invention is not limited thereto.

[0042] The beneficial effects of this invention include: (1) To address the core technical problem of interface instability between the metal electrode and the hole transport layer in perovskite solar cells, this invention designs and constructs an interface modification layer containing fluorine-containing small molecule organic matter by molecular-level structural design of the interface material system. This interface modification layer is directly formed on the upper surface of the hole transport layer and then deposited on the metal electrode (such as Ag or Au electrode). The interface modification layer of this invention significantly inhibits the diffusion of metal ions, interfacial chemical reactions, and migration of the HTL doping system in the interface region between the metal electrode and the hole transport layer (HTL) in perovskite solar cells, thereby improving the long-term stability of the device. The stability improvement is significant and reliable, including thermal stability, light stability, and bias stability. (2) The interface modification layer of the present invention uses fluorine-containing small molecule organic compounds, whose CF bonds have high stability and strong hydrophobicity, and can form a densely packed film on the HTL surface. This film can not only effectively isolate the direct contact between the HTL doping system and the metal electrode, but also regulate the interface energy level through fluorine atoms, making the hole extraction process smoother without sacrificing the initial efficiency. The chemical nature of the interface modification layer of the present invention is different from that of traditional oxide barrier layers or simple polymer capping layers. It belongs to molecular-level interface regulation, providing a new strategy for metal diffusion suppression. (3) Metal ion diffusion is one of the fundamental causes of interface failure. The interface modification layer of the present invention can form stable hydrogen bonds with the hole transport layer, enabling the fluorine-containing small molecule organic compound to be directionally adsorbed on the metal surface and form a strong chemical bonding layer. In addition, chemical molecules containing two or more fluorine molecules can form a hydrogen bond network in the interface region, which greatly improves the mechanical strength and compactness of the interface layer, thereby blocking the migration path of metal atoms. The fluorine-containing small molecule organic compound of the present invention forms chemical passivation of the interface rather than just physical coverage, thereby achieving the root cause suppression of metal ion diffusion; the fluorine-containing small molecule organic compound of the present invention can improve the energy level matching between HTL and metal electrode, without reducing the initial efficiency of the device, while traditional protective layers often have the problem of increased series resistance; (4) The interface modification layer of the present invention can be prepared by solution spin coating to form an effective interface layer without vacuum evaporation, and is fully compatible with perovskite process. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0044] Figure 1 The device structure diagrams of the perovskite solar cells prepared in Examples 1-6 are shown; Figure 2 A comparison graph of the current density-voltage curves and the incident-reflected light-electron conversion efficiency test graphs of the perovskite solar cells prepared in Example 1 and Comparative Example 1 are shown. Figure 3 A comparison graph of the current density-voltage curves of the perovskite solar cells prepared in Example 2 and Comparative Example 1 is shown. Figure 4 A comparison graph of the current density-voltage curves of the perovskite solar cells prepared in Example 3 and Comparative Example 1 is shown. Figure 5 A comparison graph of the current density-voltage curves of the perovskite solar cells prepared in Example 4 and Comparative Example 1 is shown. Figure 6 A comparison graph of the current density-voltage curves of the perovskite solar cells prepared in Example 5 and Comparative Example 1 is shown. Figure 7 A comparison graph of the current density-voltage curves of the perovskite solar cells prepared in Example 6 and Comparative Example 1 is shown. Figure 8 Atomic force microscopy (AFM) images of the thin films of the perovskite solar cells prepared in Example 1 and Comparative Example 1 are shown. Figure 9 The water contact angle (WCA) test diagrams of the perovskite solar cells prepared in Example 1 and Comparative Example 1 are shown. Figure 10 Cross-sectional scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) images of the perovskite solar cells prepared in Example 1 and Comparative Example 1 are shown. Figure 11 The three-dimensional spatial distribution of the surface contact potential difference (CPD) of the perovskite solar cells prepared in Example 1 and Comparative Example 1 is shown. Figure 12 Photoluminescence (PL) intensity curves and time-resolved PL decay curves for PVK, Example 1, and Comparative Example 1 are shown. Figure 13 The X-ray photoelectron spectroscopy (XPS) spectra of silver in the perovskite solar cells prepared in Example 1 and Comparative Example 1 are shown. Figure 14 The X-ray photoelectron spectroscopy (XPS) spectra of iodine in the perovskite solar cells prepared in Example 1 and Comparative Example 1 are shown. Figure 15 The X-ray photoelectron spectroscopy (XPS) spectra of sulfur in the perovskite solar cells prepared in Example 1 and Comparative Example 1 are shown. Figure 16 The current-voltage (IV) characteristics of three samples—Example 1, Comparative Example 1, and perfluorinated resin—in the range of -2 V to 2 V are shown. Figure 17 The SCLC test results of the perovskite solar cells prepared in Example 1 and Comparative Example 1 are shown in the figure. Figure 18 The electrochemical impedance spectra of the perovskite solar cells prepared in Example 1 and Comparative Example 1 are shown. Figure 19 The results of thermal stability and stability under certain humidity tests of the perovskite solar cells prepared in Example 1 and Comparative Example 1 are shown in the figure. Figure 20 The normalized photoelectric conversion efficiency of the perovskite solar cells prepared in Example 1 and Comparative Example 1 is shown as a trend over time, measured under ISOS-L-1 conditions (room temperature, low light). Detailed Implementation

[0045] This invention discloses an interface modification layer, its preparation method and application, and perovskite solar cells.

[0046] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0047] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0048] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0049] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is merely intended to better illustrate the invention and is not intended to limit the scope of the invention unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0050] Furthermore, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any value inevitably contains standard deviations due to individual test methods. Therefore, unless explicitly stated otherwise, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately". Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0051] In the following examples or test cases, the perfluorinated resin (Nafion) (CAS No. 31175-20-9, purity: 20) was used. The following raw materials and reagents were used: a mixture of low-fatty alcohols and water (wt.%) containing 34% water, purchased from Maclean's; perfluorobutane sulfonic acid (CAS No. 375-73-5, purity ≥98%, purchased from Maclean's); 2,3,4,5,6-pentafluorobenzenesulfonic acid (CAS No. 313-50-8, purity ≥95%, purchased from Henan Weitixi Chemical Technology Co., Ltd.); 2,3,4,5,6-pentafluorobenzoic acid (CAS No. 602-94-8, purity ≥98%, purchased from Maclean's); 2,3,4,5,6-pentafluorophenylphosphonic acid (CAS No. 137174-84-6, purity ≥98%, purchased from Shenzhen Ruixun Optoelectronic Materials Technology Co., Ltd.); pentafluorobenzene-1-thiol (CAS No. 771-62-0, purity ≥95%, purchased from Shanghai Haohong Pharmaceutical Technology Co., Ltd.); and all other raw materials and reagents used were commercially available.

[0052] In the following test examples, the device's light stability was tested in air under continuous sunlight intensity for one hour, with the temperature controlled at 20-30°C and 30%RH.

[0053] The present invention will be further illustrated below with reference to the embodiments: Example 1 The perovskite solar cell with a nip structure in this embodiment is as follows: glass / FTO (or ITO) conductive substrate / electron transport layer (ETL) / perovskite absorber layer (PVK) / hole transport layer (HTL, such as Spiro-OMeTAD) / interface modification layer of the present invention / Ag or Au metal electrode.

[0054] The perovskite solar cell provided in this embodiment is prepared by the following method: S1. Conductive Glass Cleaning Process: Cleaning the Transparent Conductive Substrate: Take an ITO conductive glass substrate with dimensions of 1.5 cm × 1.5 cm and perform ultrasonic cleaning. Immerse the substrate in deionized water containing approximately 2% detergent and ultrasonically clean for 15 minutes to remove surface oil and particulate matter. Then, thoroughly rinse the substrate with deionized water to ensure no detergent residue remains. Next, immerse the substrate in anhydrous ethanol and anhydrous isopropanol sequentially, and ultrasonically clean for 10 minutes in each solvent to remove organic contaminants. After cleaning, dry the substrate surface with high-purity nitrogen gas for later use.

[0055] Preparation of S2 and ETL: The SnO2 colloidal solution prepared above was filtered through a polyethersulfone filter and set aside. The prepared ITO glass was treated with ultraviolet ozone (UV-O3) for 15 min to increase surface hydrophilicity and promote uniform deposition of the subsequent film. Then, 40 μL of the filtered SnO2 colloidal solution was dropped onto the UV-O3 treated ITO substrate using a pipette and spin-coated at 3000 rpm for 30 s to ensure film uniformity and density. The spin-coated substrate was pre-baked at 100℃ for 10 min, and then annealed at 150℃ for 30 min to form an ETL with a thickness of approximately 50 nm.

[0056] S3. PVK Absorbing Layer Preparation Process: Two-step preparation of the PVK layer: ITO / SnO2 film is UV-O3 treated for 15 min, while PbI2 and FAI solutions are filtered and set aside. Transferred to a glove box, in the first step, 20-30 μL of PbI2 solution is spin-coated at 1000 rpm for 30 s, followed by annealing at 70℃ for 1 min. In the second step, 110 μL of organic FAI solution is spin-coated onto the film at 4000 rpm for 30 s, and then transferred to air and annealed at 150℃ for 15 min. During annealing, the mixed organic layer permeates into the PbI2 to react and form a PVK absorbing layer with a thickness of approximately 500 nm.

[0057] Preparation of S4 and HTL: Spiro solution (with Li-TFSI and TBP as dopant) was filtered outside the glove box. 30 μL of the solution was dropped onto the PVK light-absorbing layer under a nitrogen atmosphere in the glove box and spin-coated at 3000 rpm for 30 s to form an HTL with a thickness of about 150 nm.

[0058] S5. Preparation of the interface modification layer: Dissolve the perfluorinated resin (Nafion) in IPA and sonicate for 5 min to obtain an interface solution with a concentration of 10 mg / mL; under a nitrogen atmosphere in a glove box, take 40 μL of the interface solution and drop it onto HTL, and spin coat it at 5000 rpm for 30 s.

[0059] S6. Evaporation of metal electrodes: The device is placed in an environment with a relative humidity of approximately 20% and left to stand for 12 hours to allow HTL (Spiro-OMeTAD) to undergo oxidation doping. The oxidized sample is then fixed on the sample stage of a vacuum evaporation apparatus, with the vacuum level reduced to better than 5 × 10⁻⁶. -4 Pa was used to deposit an Ag electrode with a thickness of 100 nm using a thermal evaporation process, and the sample was removed after cooling to room temperature.

[0060] Example 2 The fabrication method of the nip structure perovskite solar cell provided in this embodiment is largely the same as that in Example 1, except that the preparation step of the interface modification layer in S5 is as follows: Perfluorobutane sulfonic acid was dissolved in IPA and sonicated for 5 min to obtain an interfacial solution with a concentration of 6 mg / mL. Under a nitrogen atmosphere in a glove box, 40 μL of the interfacial solution was dropped onto HTL and spin-coated at 5000 rpm for 30 s.

[0061] Example 3 The fabrication method of the nip structure perovskite solar cell provided in this embodiment is largely the same as that in Example 1, except that the preparation step of the interface modification layer in S5 is as follows: 2,3,4,5,6-pentafluorobenzenesulfonic acid was dissolved in IPA and sonicated for 5 min to obtain an interfacial solution with a concentration of 7.5 mg / mL. 40 μL of the interfacial solution was dropped onto HTL under a nitrogen atmosphere in a glove box and spin-coated at 5000 rpm for 30 s.

[0062] Example 4 The fabrication method of the nip structure perovskite solar cell provided in this embodiment is largely the same as that in Example 1, except that the preparation step of the interface modification layer in S5 is as follows: 2,3,4,5,6-pentafluorobenzoic acid was dissolved in IPA and sonicated for 5 min to obtain an interfacial solution with a concentration of 9 mg / mL. 40 μL of the interfacial solution was dropped onto HTL under a nitrogen atmosphere in a glove box and spin-coated at 5000 rpm for 30 s.

[0063] Example 5 The fabrication method of the nip structure perovskite solar cell provided in this embodiment is largely the same as that in Example 1, except that the preparation step of the interface modification layer in S5 is as follows: 2,3,4,5,6-pentafluorophenylphosphonic acid was dissolved in IPA and sonicated for 5 min to obtain an interfacial solution with a concentration of 12.5 mg / mL. 40 μL of the interfacial solution was dropped onto HTL under a nitrogen atmosphere in a glove box and spin-coated at 5000 rpm for 30 s.

[0064] Example 6 The fabrication method of the nip structure perovskite solar cell provided in this embodiment is largely the same as that in Example 1, except that the preparation step of the interface modification layer in S5 is as follows: Pentafluorobenzene-1-thiol was dissolved in IPA and sonicated for 5 min to obtain an interfacial solution with a concentration of 14 mg / mL. 40 μL of the interfacial solution was dropped onto HTL under a nitrogen atmosphere in a glove box and spin-coated at 5000 rpm for 30 s.

[0065] Figure 1 The following are device structure diagrams of the perovskite solar cells obtained in Examples 1-6, as shown. Figure 1 As shown, the structure of its perovskite solar cell, from bottom to top, consists of: conductive substrate (ITO), electron transport layer (ETL), perovskite absorber layer (PVK), hole transport layer (HTL), interface modification layer (Interface), and metal electrode (Ag / Au).

[0066] Comparative Example 1 The nip structure perovskite solar cell of this comparative example is shown below: glass / FTO (or ITO) conductive substrate / electron transport layer (ETL) / perovskite absorber layer (PVK) / hole transport layer (HTL, such as Spiro-OMeTAD) / Ag or Au metal electrode. That is, compared with Examples 1-6, there is no interface modification layer in the cell.

[0067] The perovskite solar cell provided in this embodiment is prepared by the following method: S1. Conductive Glass Cleaning Process: Cleaning the Transparent Conductive Substrate: Take an ITO conductive glass substrate with dimensions of 1.5 cm × 1.5 cm and perform ultrasonic cleaning. Immerse the substrate in deionized water containing approximately 2% detergent and ultrasonically clean for 15 minutes to remove surface oil and particulate matter. Then, thoroughly rinse the substrate with deionized water to ensure no detergent residue remains. Next, immerse the substrate in anhydrous ethanol and anhydrous isopropanol sequentially, and ultrasonically clean for 10 minutes in each solvent to remove organic contaminants. After cleaning, dry the substrate surface with high-purity nitrogen gas for later use.

[0068] Preparation of S2 and ETL: The SnO2 colloidal solution prepared above was filtered through a polyethersulfone filter and set aside. The prepared ITO glass was treated with ultraviolet ozone (UV-O3) for 15 min to increase surface hydrophilicity and promote uniform deposition of the subsequent film. Then, 40 μL of the filtered SnO2 colloidal solution was dropped onto the UV-O3 treated ITO substrate using a pipette and spin-coated at 3000 rpm for 30 s to ensure film uniformity and density. The spin-coated substrate was pre-baked at 100℃ for 10 min, and then annealed at 150℃ for 30 min to form an ETL with a thickness of approximately 50 nm.

[0069] S3. PVK Absorbing Layer Preparation Process: Two-step preparation of the PVK layer: ITO / SnO2 film is UV-treated for 15 min, while PbI2 and FAI solutions are filtered and set aside. Transferred to a glove box, in the first step, 20-30 μL of PbI2 solution is spin-coated at 1000 rpm for 30 s, followed by annealing at 70℃ for 1 min. In the second step, 110 μL of organic FAI solution is spin-coated onto the film at 4000 rpm for 30 s, and then transferred to air for annealing at 150℃ for 15 min. During annealing, the mixed organic layer permeates into the PbI2 to react and form a PVK absorbing layer with a thickness of approximately 500 nm.

[0070] Preparation of S4 and HTL: Spiro solution (with Li-TFSI and TBP as dopants) was filtered outside the glove box. 30 μL of the solution was dropped onto the PVK light-absorbing layer under a nitrogen atmosphere in the glove box and spin-coated at 3000 rpm for 30 s to form an HTL with a thickness of about 150 nm.

[0071] S5. Evaporation of metal electrodes: The device is placed in an environment with a relative humidity of approximately 20% and left to stand for 12 hours to allow HTL (Spiro-OMeTAD) to undergo oxidation doping. The oxidized sample is then fixed on the sample stage of a vacuum evaporation apparatus, with the vacuum level reduced to better than 5 × 10⁻⁶. -4 Pa was used to deposit an Ag electrode with a thickness of 100 nm using a thermal evaporation process, and the sample was removed after cooling to room temperature.

[0072] Test Example 1: Battery Performance Test The solar cells prepared in Examples 1-6 and Comparative Example 1 were subjected to performance tests. The test conditions were as follows: an AAA-grade solar simulator (Zhuoli Hanguang, SolarIV-150A) equipped with an AM 1.5G filter was used as the light source, and the irradiance was calibrated to 100 mW / cm² using a standard monocrystalline silicon reference cell (KG5, NREL certified). 2 The device was tested at 25°C, and a precise stainless steel mask was used to define the effective illumination area of ​​the device as 0.0625 cm². 2 The current-voltage characteristic curves were measured using a digital source meter (Keithley 2400) with bidirectional voltage scanning (from 1.2 V to -0.1 V) at a scan rate of 0.1 V / s.

[0073] Figures 2-7 The current density-voltage (JV) curves of Examples 1-6 and Comparative Example 1 are shown in comparison. The test data are shown in Table 1 below: Table 1. Battery performance test results of Examples 1-6 and Comparative Example 1

[0074] Table 1 and Figure 2-7 In this context, Jsc represents short-circuit current density, Voc represents open-circuit voltage, FF represents fill factor, and PCE represents photoelectric conversion efficiency.

[0075] From Table 1 and Figure 2-7 It can be seen that, compared with Comparative Example 1, the perovskite solar cells prepared in Examples 1-6 of this invention by introducing fluorine-containing small-molecule organic compounds between the HTL and the metal electrode exhibit significantly improved photoelectric performance indicators such as short-circuit current density, open-circuit voltage, fill factor, and photoelectric conversion efficiency. Furthermore, Figure 2 The right side shows the differential current density versus voltage curves of the perovskite solar cells prepared in Example 1 and Comparative Example 1. The perovskite solar cell prepared in Example 1 achieves a current density of 24.87 mA / cm² at its maximum power point. 2 It was significantly higher than the 24.51 mA / cm² of Comparative Example 1. 2 This indicates that its device has superior output capability.

[0076] Test Example 2: Performance Testing of the Interface Decoration Layer Figure 8 These are atomic force microscopy (AFM) images of the interface modification layers of the perovskite solar cells prepared in Example 1 and Comparative Example 1. Li-TFSI and TBP were used as dopants in Spiro-OMeTAD, and a layer of Nafion was spin-coated onto this HTL for modification. The roughness (RMS) decreased from 9.20 nm to 6.91 nm. The Li in the HTL... + Significant aggregation and uneven distribution were observed on the sample surface. However, after Nafion modification, the Nafion was uniformly distributed on the HTL and improved the Li... + The distribution should be uniform.

[0077] Figure 9 The figures show the water contact angle (WCA) test results of the interface-modified layers prepared in Example 1 and Comparative Example 1. The WCA of Comparative Example 1 was 80.9°, while the WCA of the HTL modified with Nafion in Example 1 was 84.3°. Since the perfluorinated resin contains a large amount of fluorine (F), which has high electronegativity and strong hydrophobicity, and is uniformly distributed on the surface of the HTL, it indicates that the hydrophobicity of the HTL modified with the perfluorinated resin is enhanced. This helps to reduce water vapor wetting and interfacial ion / metal migration, thereby enhancing the stability of the device.

[0078] Figure 10These are cross-sectional scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) images of the perovskite solar cells prepared in Example 1 and Comparative Example 1 after 90 days of light aging.

[0079] Depend on Figure 10 In the left image, in the battery device of Comparative Example 1, cross-sectional SEM reveals that the interface of the Ag / HTL / PVK / SnO2 / ITO / Glass device structure has become blurred and rough, making it impossible to determine whether Ag and HTL are separated. It can be seen that Ag and HTL are intertwined, severely affecting the stability of HTL. Furthermore, the PVK layer grains are amorphous, failing to maintain their original morphology and spacing, indicating significant decomposition throughout the PVK layer. Elemental analysis of the corresponding regions yields an Ag distribution map. The Ag signal is not only concentrated in the Ag electrode region but also abundant within the HTL and PVK layers, even migrating downwards into the SnO2 region. This indicates significant vertical migration and diffusion of Ag, accumulating in large quantities at the PVK or HTL bulk phase and interface, reflecting obvious interface / PVK degradation in the device.

[0080] Depend on Figure 10 The right-hand image shows that in the battery device of Example 1, after introducing a Nafion interface modification layer between Ag and HTL, cross-sectional SEM reveals clear interface spacing, with each layer's interface being flat and continuous. The PVK layer exhibits dense grains and a complete morphology, especially the Ag electrode and HTL layer, which are well-separated without significant decomposition. The corresponding Ag elemental distribution map clearly shows that the Ag signal is mainly concentrated in the top electrode and adjacent region, and almost no obvious Ag signal is observed in the HTL / Nafion interface modification layer and the PVK layer below it. This indicates that the Nafion interface modification layer can form an effective ion barrier layer, inhibiting Ag+ migration into the PVK layer and its erosion, and also inhibiting I+ ion penetration. - Through the voids created by TBP volatilization in HTL and Ag + By combining with AgI to form Nafion, Nafion can fill the voids created by TBP volatilization and also inhibit Li + It absorbs moisture from the air and fills the voids on the surface of HTL.

[0081] Figure 11These are three-dimensional spatial distribution maps of the surface contact potential difference (CPD) of the perovskite solar cells prepared in Example 1 and Comparative Example 1. Comparative Example 1 exhibits obvious potential fluctuation regions, a wide CPD value distribution range, and significant potential difference variations, indicating a large degree of surface inhomogeneity, charge traps, or local defect regions. Example 1 shows a high degree of consistency in potential distribution, with minimal variation in CPD values ​​across the entire region and a smoother surface potential, indicating a more uniform surface work function and a more regular arrangement of electron energy levels, which is beneficial for stable electron injection and transport in the device. The three-dimensional CPD distribution maps show that Example 1 is far superior to the Comparative Example in terms of potential distribution uniformity, indicating a significant improvement in its surface electrical properties and making it more suitable for the fabrication of high-performance optoelectronic devices.

[0082] Figure 12 The figures show the photoluminescence (PL) intensity curves and time-resolved PL decay curves for PVK, Example 1, and Comparative Example 1. The perovskite layer exhibits the strongest PL luminescence intensity, indicating that its radiative recombination process is most significant. The PL intensities of Comparative Example 1 and Example 1 are both lower than those of PVK, with Example 1 showing the lowest intensity, indicating that it has a stronger non-radiative recombination process, or more efficient carrier transfer behavior, which is beneficial for improving photoelectric conversion efficiency. The carrier lifetime of the perovskite layer is 964.7 ns, compared to 237.8 ns for Comparative Example 1 and 80.9 ns for Example 1, showing a significantly shorter lifetime. The shorter lifetime indicates that carriers migrate more rapidly in Example 1, suggesting a faster electron or hole transfer rate and better control of the recombination process. This behavior is often a desirable characteristic for high-performance devices, especially in solar cells or photodetectors, where it can effectively reduce carrier recombination losses.

[0083] Figure 13 These are X-ray photoelectron spectroscopy (XPS) spectra of silver in the perovskite solar cells prepared in Example 1 and Comparative Example 1, with a focus on Ag 3d. 5 / 2 With Ag 3d 3 / 2 Two characteristic peaks. In Comparative Example 1, Ag 3d 5 / 2 and Ag 3d 3 / 2 The binding energies in Example 1 were 368.4 eV and 374.4 eV, respectively; while in Example 2, the corresponding binding energies decreased to 368.2 eV and 374.2 eV, respectively, representing a redshift of approximately 0.2 eV. This shift in binding energy indicates that the electronic environment of silver changed in Example 1, presumably due to enhanced interactions between silver and surrounding ligands or the substrate, or due to increased electron density, causing the chemical state of silver atoms to be more biased towards a lower valence state.

[0084] Figure 14 These are X-ray photoelectron spectroscopy (XPS) spectra of iodine in the perovskite solar cells prepared in Example 1 and Comparative Example 1. In Comparative Example 1, I 3d5 / 2 and I 3d 3 / 2 The binding energies of the two elements are located at 619.6 eV and 631.1 eV, respectively; in Example 1, the corresponding binding energies are slightly red-shifted to 619.4 eV and 630.9 eV, with an energy shift of approximately -0.2 eV. This slight decrease in binding energy indicates that the chemical environment of iodine in Example 1 has changed, presumably due to enhanced electronic interactions between iodine and surrounding metal ions or the structural matrix, resulting in an increased electron cloud density of iodine and thus a decrease in binding energy.

[0085] Figure 15 These are the X-ray photoelectron spectroscopy (XPS) spectra of sulfur in the perovskite solar cells prepared in Example 1 and Comparative Example 1. The two main characteristic peaks correspond to S 2p, respectively. 3 / 2 and S 2p 1 / 2 In Comparative Example 1, the binding energies of S 2p were 168.3 eV and 169.3 eV, respectively; in Example 1, these two peaks showed a slight red shift to 168.2 eV and 169.5 eV. This shift in binding energy between 0.1 and 0.2 eV indicates a slight change in the electronic environment of the sulfur atom, presumably due to altered bonding strength or enhanced charge transfer with the metal ion, reflecting a more stable chemical state or electron enrichment of sulfur in the material. This change helps explain the mechanism of improved electrical properties or interface stability in Example 1, particularly in applications such as interface engineering or charge transport path optimization.

[0086] Figure 16 This is a current-voltage (IV) characteristic graph of three samples—Example 1, Comparative Example 1, and perfluorinated resin—in the range of -2 V to 2 V. (From...) Figure 16 The conductivity of Comparative Example 1 is 0.507 mS·cm. -1 The conductivity of Example 1 was increased to 0.963 mS·cm. -1 The perfluorinated resin exhibits the highest electrical conductivity, at 1.593 mS·cm. -1 It can be seen that the electrical conductivity of Example 1 is significantly better than that of Comparative Example 1, indicating that interface optimization effectively improves the charge transport capability of the material. This result shows that Example 1 has significant optimization in electron or ion transport, and its interface modification layer is suitable as a charge transport layer in optoelectronic devices (such as HTL), or for application in functional polymer films requiring high conductivity.

[0087] Figure 17The graph shows the SCLC test results of the perovskite solar cells prepared in Example 1 and Comparative Example 1. The measurement results are presented as a double logarithmic relationship between logarithmic current density and voltage. The straight line portion in the graph represents the J ∝ V² region, i.e., the linear fitting region conforming to the SCLC model. The defect state density of Comparative Example 1 and Example 1 is 2.91 × 10⁻⁶. -15 cm -3 Reduced to 1.17×10 -15 cm -3 This indicates that the device in Example 1 has a lower defect state density, which significantly improves its mobility and helps reduce recombination, improve the device fill factor and efficiency.

[0088] Figure 18 These are the electrochemical impedance spectra of the perovskite solar cells prepared in Example 1 and Comparative Example 1. Figure 18 The illustration shows the equivalent circuit model, including the series resistance (R). s ), charge transfer resistance (R) ct ) and composite resistor (R) rec ).Depend on Figure 18 The transmission resistance (R) of the device in the high-frequency region ct The resistance decreased from 48.5 kΩ in Comparative Example 1 to 24.5 kΩ in Example 1, indicating that introducing a perfluorinated resin interface between the HTL and the metal electrode helps improve carrier transport at the interface, reducing the charge injection barrier and interface resistance. This corroborates the previously mentioned increase in conductivity. Furthermore, compared to Comparative Example 1, the device in Example 1 showed a lower recombination resistance (R0) in the low-frequency region. rec The R value increased significantly from 1.76 MΩ to 2.06 MΩ. rec The increase of approximately 0.3 MΩ indicates that the introduction of perfluorinated resin significantly suppressed the recombination process of charge carriers in the device, making them less susceptible to recombination. These results demonstrate that the structural design or material control in this invention significantly reduces interfacial charge transport impedance, improves overall conductivity, and contributes to enhancing the device's response efficiency in photoelectric conversion or electrochemical performance.

[0089] Figure 19 These are graphs showing the results of thermal stability and humidity stability tests on the perovskite solar cells prepared in Example 1 and Comparative Example 1. Figure 19 It can be seen that the perovskite solar cell prepared in Example 1 retains 89% of its initial efficiency after being stored at 65°C for 600 hours; and still retains 91% of its initial efficiency after being stored under ISOS-D-1 conditions for 3000 hours, demonstrating the stability of the solar cell of the present invention. In contrast, the solar cell prepared under the same conditions as Comparative Example 1 shows a significant decrease in both efficiency and stability.

[0090] Figure 20This shows the normalized photoelectric conversion efficiency over time of the perovskite solar cells prepared in Example 1 and Comparative Example 1 under ISOS-L-1 conditions (room temperature, low light). Figure 20 The device prepared in Comparative Example 1 showed an efficiency drop to 73% of its initial value after approximately 600 hours; the device prepared in Example 1, however, maintained an initial efficiency of 88% after approximately 1500 hours, demonstrating significantly higher stability. This indicates that Example 1 optimized the device structure, interface engineering, and packaging stability, effectively suppressing material degradation caused by light and environmental factors, and significantly improving the device's operating life.

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An interface modification layer located between a hole transport layer and a metal electrode of a perovskite solar cell, the interface modification layer comprising a fluorine-containing small molecule organic.

2. The interface modification layer of claim 1, wherein, The fluorine-containing small molecule organic is selected from one or more of a naphthalene full fluorinated ion exchange resin, a small molecule containing a perfluoroalkyl side chain, and a small molecule containing a polyfluorosubstituted aromatic ring structure. Preferably, the small molecule containing a perfluoroalkyl side chain is selected from a perfluoroalkyl sulfonic acid, a perfluoroalkyl phosphoric acid, a perfluoroalkyl carboxylic acid, or a perfluoroalkyl mercaptan, more preferably, the alkyl of the small molecule containing a perfluoroalkyl side chain can be butane, hexane, or decane. Preferably, the small molecule containing a polyfluorosubstituted aromatic ring structure is selected from a polyfluoroaryl sulfonic acid-containing organic, a polyfluoroaryl carboxylic acid-containing organic, a polyfluoroaryl phosphoric acid-containing organic, or a polyfluoroaryl mercaptan-containing organic; more preferably, the polyfluoroaryl sulfonic acid-containing organic is 2,3,4,5,6-pentafluorobenzenesulfonic acid or 4-(trifluoromethyl)benzenesulfonic acid, the polyfluoroaryl carboxylic acid-containing organic is 2,3,4,5,6-pentafluorobenzoic acid or 4-(trifluoromethyl)benzoic acid, the polyfluoroaryl phosphoric acid-containing organic is 2,3,4,5,6-pentafluorobenzenephosphonic acid, and the polyfluoroaryl mercaptan-containing organic is pentafluorobenzene-1-thiol.

3. The interface modification layer of claim 1 or 2, wherein, The thickness of the interface modification layer is 1-20 nm, preferably 3-8 nm.

4. A method for preparing the interface modification layer of any one of claims 1 to 3, comprising the steps of: S1. preparing an interface solution containing the fluorine-containing small molecule organic; S2. forming the interface modification layer from the interface solution by a solution spin coating method.

5. The method of claim 4, wherein, In step S1, the solvent of the interface solution is isopropyl alcohol and / or anhydrous ethanol; and / or, the concentration of the fluorine-containing small molecule organic in the interface solution is 1-50 mg / mL, preferably 5-20 mg / mL, more preferably 6-14 mg / mL.

6. The method of claim 4 or 5, wherein, In the step S2, the spin coating speed of the solution spin coating method is 4000-6000 rpm, and the spin coating time is 20-40 seconds.

7. The method of any one of claims 4 to 6, wherein, The thickness of the interface modification layer in the step S2 is 1-20 nm, preferably 3-8 nm.

8. Use of the interface modification layer of any one of claims 1 to 3 or prepared by the method of any one of claims 4 to 7 in a perovskite solar cell.

9. A perovskite solar cell comprising the interface modification layer of any one of claims 1 to 3 or prepared by the method of any one of claims 4 to 7.

10. The perovskite solar cell of claim 9 wherein, The perovskite solar cell comprises, in sequence, a conductive substrate, an electron transport layer, a perovskite absorption layer, a hole transport layer, the interface modification layer, and a metal electrode.

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